MXPA99005906A - Variable rate wireless telecommunication - Google Patents

Abstract

The present invention provides a transmission controller and method for processing data items to be transmitted over a wireless link connecting a central terminal and a subscriber terminal of a wireless telecommunications system, a single frequency channel being employed for transmitting data items pertaining to a plurality of wireless links. The transmission controller comprises an orthogonal code generator for providing an orthogonal code from a set of'm'orthogonal codes used to create'm'orthogonal channels within the single frequency channel, and a first encoder for combining a data item to be transmitted on the single frequency channel with said orthogonal code from the orthogonal code generator, the orthogonal code determining the orthogonal channel over which the data item is transmitted, whereby data items pertaining to different wireless links may be transmitted simultaneously within different orthogonal channels of said single frequency channel. Further, the transmission controller comprises an overlay code generator for providing an overlay code from a first set of'n'overlay codes which are orthogonal to each other, and a second encoder arranged to apply the overlay code from the overlay code generator to said data item, whereby'n'data items pertaining to different wireless links may be transmitted simultaneously within the same orthogonal channel. The invention also provides a reception controller and method for processing data items received over a wireless link.

Description

CONTROL OF INTERFERENCE IN A CELL OF A WIRELESS TELECOMMUNICATION SYSTEM TECHNICAL FIELD OF THE INVENTION The present invention relates generally to wireless telecommunications systems and more particularly to techniques for controlling interference in a cell of a wireless telecommunications system.

BACKGROUND OF THE INVENTION A wireless telecommunications system has been proposed in which a geographical area is divided into cells, each cell having one or more central terminals (CTs) for communication via wireless links with a number of subscriber terminals (STs) in the cell. These wireless links are established by predetermined frequency channels, a frequency channel typically consisting of one frequency to capture signals from a subscriber terminal to the central terminal, and another frequency to output signals from the central terminal to the subscriber terminal. Due to bandwidth restrictions, it is not practical for each individual subscriber terminal to have its own dedicated frequency channel for communication with the central terminal. Therefore, techniques need to be applied to allow data elements that refer to different communications to pass through the same frequency channel without interfering with each other. In current wireless telecommunications systems, this can be achieved through the use of a "code division multiple access" (CDMA) technique, where a set of orthogonal codes can be applied to the data elements to be transmitted through a particular frequency channel, the data elements related to different communications being combined with orthogonal codes different from the set. The signals to which an orthogonal code has been applied can be considered as being transmitted by a corresponding orthogonal channel within a particular frequency channel. Hence, if a set of 16 orthogonal codes is used, 16 orthogonal channels can be created within a single frequency channel, and therefore up to sixteen separate communication signals (corresponding to sixteen separate wireless links) can be transmitted simultaneously through a single frequency channel if different orthogonal codes are applied to each communication signal. This reduces the interference between signals transmitted by the same frequency channel in a particular cell, but does not prevent the prospect of interference from signals generated by nearby cells that happen to be using the same frequency channel. This problem is alleviated in some way by adapting a deployment arrangement where all adjacent cells use different frequency channels. However, there is only a limited number of frequency channels that can be assigned to the wireless telecommunications system. Hence it is inevitable, particularly in the densely populated area where there are many subscriber terminals and therefore each cell only covers a small geographical area, that signals from nearby cells using the same frequency channel may interfere with those generated within of a cell. Shin SM and others: "DS-DMA Reverse Link Channel Assignment based on Interference Measurements" Electronics Letters, Vol. 31, No. 22, 26 Oct 95, pages 1897-1899, XP000543364 describes a technique to reduce the so-called link capacity redundant based on the interference measurement received.

BRIEF DESCRIPTION OF THE INVENTION According to the present invention, an interference controller is provided to limit in one cell the interference effect generated by other cells of a wireless telecommunications system, each cell of the wireless telecommunications system has a central terminal and a plurality of terminals of subscriber, the communication between a central terminal and a subscriber terminal being arranged to occur via a wireless link, a plurality of multiplexed code division channels being provided within a single frequency channel to allow data in relation to a plurality of wireless links to be transmitted simultaneously within different multiplexed code division channels of the single frequency channel, the interference controller consisting of: a channel controller arranged to assign a number of the plurality of multiplexed code division channels as a group of multiplexed code division channels arranged for the establishment of wireless links; an analyzer for receiving parameters that refer to a wireless link within the indicative cell if the wireless link is subject to interference from signals generated by other cells; the analyzer is arranged to compare those parameters with predetermined criteria, and to generate an output signal that depends on the comparison; and the channel controller responding to the output signal of the analyzer to selectively reduce the number of multiplexed code division channels in the group of channels in order to reduce the interference effect of the other cells. Using the above method, the effects of interference from other cells can be suppressed, because removing a multiplexed code division channel out of commission improves the interference rejection of the remaining multiplexed code division channels. Furthermore, it is not only the interference effect of other cells that is reduced, but also the effect of any internal interference within the cell, such as interference of multiple origin, will also be reduced. Removing a multiplexed code division channel out of commission can affect the number of calls that can be handled simultaneously by the cell, but will allow the cell to retain a satisfactory quality when unaffected calls are not affected by external interference. In preferred embodiments, a parameter provided to the analyzer is the bit error rate (BER) for signals transmitted within said code division multiplexing channels, and the predetermined criterion with which the analyzer compares the BER is a threshold value. BER identifying a predetermined maximum acceptable BER, the channel controller responding to the analyzer indicating that the BER exceeds the predetermined acceptable maximum to remove a multiplexed channel of use code division. A BER signal can be provided to the analyzer for each transmission and link communication path, the BER signal giving an indication of the errors introduced by interference during the transmission of a data signal by the particular wireless link. Therefore, for each wireless link, the analyzer can be provided with information about the levels of interference experienced by those links. In addition, an additional parameter preferably provided to the analyzer is a degree of service signal (GOS) that indicates the availability of the code division multiplexing channels, and the predetermined criterion with which the analyzer compares said GOS signal is a threshold value. GOS that identifies a predetermined maximum degree of service, the channel controller responding to the analyzer indicating that the GOS signal has exceeded the predetermined maximum degree of service to remove a multiplexed channel of use code division. Preferably, each subscriber terminal and each modem by a modem shelf within the central terminal will have a call control function associated therewith. The call control function within a ST will gather information about how quickly the ST is able to acquire a link channel for incoming or outgoing calls, while the call control functions within the CT will monitor how quickly modems within the CT can establish link channels. Therefore, the analyzer in preferred modalities will receive information indicating how quickly the modems within the CT and ST are capable of acquiring channels. If the GOS exceeds that which would be considered acceptable (as indicated by the predetermined maximum GOS), then the channel controller may remove a multiplexed channel of use code division in order to reduce the interference effect within the multiplexed channels. of code division remaining. Preferably, the channel controller, upon receiving a signal from the analyzer indicating that a multiplexed code division channel must be removed from use, it is arranged to determine which multiplexed code division channel is the least heavily used, and to remove that multiplexed code division channel of use. This ensures that the least number of users are affected by the removal of the multiplex code division channel. However, it will be evident that other criteria could be used by the channel controller to decide which channel to remove. For example, the least heavily used channel may be reserved for priority calls, and therefore it may not be appropriate to remove that channel from use. In such cases, the channel controller may be arranged to remove the least heavily used channel that is driving, or reserved to handle, a priority call. Still as another alternative, it may be acceptable for the channel controller to not react to the analyzer request to remove a channel, until such time as a channel is completely free of traffic, and then to remove that channel from use. In preferred embodiments, a plurality of the multiplexed code division channels are designated as traffic channels, the analyzer is arranged to monitor the parameters in relation to interference by those traffic channels, and the channel controller is arranged to selectively designate one. or more traffic channels as blocked channels that should not be used in order to reduce the interference effect from the other cells. Preferably, if the analyzer determines that the signal BER is below a predetermined minimum BER value, the channel controller is arranged to designate one of the blocked channels as a free traffic channel which may subsequently be used for data traffic. Hence, if the interference effect through the channels is below what could be considered acceptable, then the channel controller can add another code division multiple channel to the group of traffic channels, thereby improving the GOS . Similarly, if the analyzer determines that the GOS signal has fallen below a second predetermined minimum GOS value, the channel controller is arranged to designate one of the blocked channels as a free traffic channel that can subsequently be used for data traffic. . If the GOS falls below a minimum acceptable level, then it is preferable to increase the number of available channels if possible, but this will tend to adversely affect the BER, because each channel will become more susceptible to interference. The analyzer in combination with the channel controller will try to achieve a balance where there are enough channels to provide an acceptable GOS, but not so many that the level of interference becomes unacceptable through any of the channels. In preferred embodiments, the channel controller is provided with a value indicating a maximum number of multiplexed code division channels that can be designated as traffic channels, the channel controller only adds multiplexed code division channels at the request of the analyzer if doing so would not exceed the maximum number of multiplexed code division channels. Preferably, a number of the traffic channels are reserved as call channels, and a number of the traffic channels are designated as free channels, and if a call channel is used to pass data calls, the channel controller is arranged to designate a free channel as a call channel if a free channel is available, thereby improving the opportunity for a call channel to be available for a subsequent call. In preferred embodiments, the multiplexed code division channels are orthogonal channels, a set of orthogonal codes being used to create the orthogonal channels. In preferred embodiments of the present invention, an interference controller according to the invention is provided within a central terminal for a cell of a wireless telecommunications system., the telecommunications system has a plurality of cells, each cell has a central terminal and a plurality of subscriber terminals, communication between the central terminal and the subscriber terminal in the cell being arranged to occur through a wireless link, a plurality of of multiplexed code division channels being provided within a single frequency channel to allow data elements in relation to a plurality of wireless links to be transmitted simultaneously within different multiplexed code division channels of a single frequency channel. The provision of the interference controller within the central terminal allows the TC to limit the interference effect generated by other cells of the wireless telecommunications system.

In such embodiments, the central terminal would typically consist of: an orthogonal code generator for providing an orthogonal code from a set of orthogonal codes used to create the multiplexed code division channels within a single frequency channel; a first encoder for combining a data element to be transmitted by the only frequency channel with the orthogonal code from the orthogonal code generator, the orthogonal code determining the multiplexed code division channel by which the data elements are transmitted, thus allowing the data elements in relation to different wireless links to be transmitted simultaneously within different multiplexed code division channels of a single frequency channel. Seen from a further aspect, the present invention provides a wireless telecommunications system comprising a plurality of cells, each cell having a central terminal and a plurality of subscriber terminals, communication between a central terminal and a subscriber terminal within a cell being arranged to occur via a wireless link, a plurality of multiplexed code division channels being provided within a single frequency channel to allow data relative to a plurality of wireless links to be transmitted simultaneously within different multiplexed division channels code of a single frequency channel, at least one cell of the wireless telecommunications system consisting of an interference controller according to the present invention for limiting the interference effect generated by other cells of the wireless telecommunications system. In preferred embodiments, the interference controller may additionally consist of a transmit controller to process data to be transmitted over a wireless link connecting a central terminal and a subscriber terminal of a wireless telecommunications system, a single frequency channel being used. to transmit data in relation to a plurality of wireless links, the transmission controller costing: an orthogonal code generator to provide an orthogonal code from a set of orthogonal codes "m" used to create "m" orthogonal channels within a single frequency channel; a first encoder for combining data to be transmitted by a single frequency channel with the orthogonal code from the orthogonal code generator, the orthogonal code determining the orthogonal channel by means of which the data is transmitted, where the data in relation to different links wireless can be transmitted simultaneously within different orthogonal channels of a single frequency channel; a code generator set to provide a code by means of a first set of "n" superimposed codes that are orthogonal to each other; and a second decoder arranged to apply the code by placing it from the code generator by means of the data element, wherein the "n" data elements in relation to different wireless links can be transmitted simultaneously within the same orthogonal channel. Additionally, or alternatively, the interference controller may additionally consist of a receiving controller for processing data elements received via a wireless link connecting a central terminal and a subscriber terminal of a wireless telecommunications system, a single frequency channel being used to transmit data elements in relation to a plurality of wireless links, the receiving controller consisting of: an orthogonal code generator to provide an orthogonal code of a set of "m" orthogonal codes used to create "m" orthogonal channels within single-frequency channel; a first decoder for applying, to signals received by a single frequency channel, the orthogonal code provided by the orthogonal code generator, in order to isolate the transmitted data elements within the corresponding orthogonal channel; a code generator put together to provide a code by placing from a first set of "n" superimposed codes that are orthogonal to each other, the set of "n" superimposed codes allowing "n" data elements in relation to different wireless links to be transmitted simultaneously within the same orthogonal channel; and a second decoder for applying, to the data elements of the orthogonal channel, the code by being set from the code generator via set as to isolate a particular data element transmitted using that code through set. Using superimposed codes in addition to a known set of orthogonal codes, it is possible for selected orthogonal channels to be subdivided to form additional orthogonal channels. For example, if there are 16 orthogonal channels originally and a set of four overlapping codes is defined, each orthogonal channel being subject to orthogonal codes, then up to 64 orthogonal channels can be defined. By applying appropriate orthogonal codes and superimposed codes, up to 64 separate communication signals could be sent simultaneously through a single frequency channel, albeit at a quarter of the speed that communication signals could be transmitted if overlapping codes were not used. . Such method has the advantage that it retains compatibility with current hardware and software equipment that uses the set of orthogonal codes, but which does not support the use of overlapping codes. By designating certain orthogonal channels as channels for which overlapping codes are not used, the current equipment can communicate through those channels without requiring any change to the equipment. In another preferred embodiment, the interference controller may further comprise a transmission controller for processing data elements to be transmitted via a wireless link connecting a central terminal and a subscriber terminal of a wireless telecommunications system, a single channel of communication. frequency being used to transmit data elements in relation to a plurality of wireless links, the transmission controller consisting of: an orthogonal code generator to provide an orthogonal code of a set of "m" orthogonal codes used to load "m" channels orthogonal within a single frequency channel; a first encoder for combining a data element to be transmitted by a single frequency channel with the orthogonal code of the orthogonal code generator, the orthogonal code determining the orthogonal channel by means of which the data element is transmitted, whereby the elements of data in relation to different wireless links can be transmitted simultaneously within different orthogonal channels of a single frequency channel; and a TDM encoder arranged to apply time division multiplexing (TDM) techniques to the data element in order to insert the data element into a time segment of the orthogonal channel, whereby a plurality of data elements in Relationship to different wireless links can be transmitted within the same orthogonal channel during a predetermined frame period. Additionally, or alternatively, the interference controller may comprise in addition to a receiving controller for processing data elements received via a wireless link connecting a central terminal and a subscriber terminal of a wireless telecommunications system, a single frequency channel being used to transmit data elements in relation to a plurality of wireless links, and "m" orthogonal channels being provided within the single frequency channel, the receiving controller consisting of: an orthogonal code generator to provide an orthogonal code from a set of "m" orthogonal codes used to create the aforementioned "m" orthogonal channels within a single frequency channel; a first decoder for applying, to signals received by a single frequency channel, the orthogonal code provided by the orthogonal code generator, in order to isolate the transmitted data elements within the corresponding orthogonal channel; and a TDM encoder arranged to extract a data element from a predetermined time segment within the orthogonal channel, a plurality of data elements in relation to different wireless links being transmitted within the same orthogonal channel during a predetermined frame period. Using TDM techniques in addition to a known set of orthogonal codes, it is possible that selected orthogonal channels are subdivided into the time dimension. For example, if the TDM is used to divide a period table into four subframes, and each orthogonal channel is subject to the TDM technique, then up to four separate communication signals can be transmitted through the 16 orthogonal channels during a period frame, although at a quarter of the speed that the communication signals would be transmitted if the TDM technique was not used.Such method has the advantage that it retains compatibility with current hardware and software equipment which uses the set of orthogonal codes, but which does not support the use of TDM technique. By designating certain orthogonal channels as channels for which TDM is not used, the current equipment can communicate through those channels without requiring any change to the equipment. In preferred embodiments, the interference controller may additionally consist of a channel selection controller for establishing a wireless link connecting a central terminal and a subscriber terminal of a wireless telecommunications system, at least two frequency channels being provided by the which the wireless link could be established, the channel controller consisting of: a storage for storing data identifying at least two frequency channels; a selector to select a frequency channel from those listed in the storage; link acquisition logic to establish a wireless link through the frequency channel selected by the selector; the selector responding to the link acquisition logic that is unable to establish the wireless link, to select an alternate frequency channel from those listed in the storage. With this method, it is possible to increase the number of subscriber terminals that can be supported by the wireless telecommunications system, because a frequency channel is fully utilized at the moment in which a wireless link connecting a particular subscriber terminal with a central terminal is required, then another frequency channel may be selected for the establishment of that wireless link. Previously this could not be possible, because the subscriber terminal would be arranged to only communicate with a central terminal using a predefined frequency channel. Seen from a further aspect, the present invention provides a method for limiting in one cell the interference effect generated by other cells of a wireless telecommunications system, each cell of the wireless telecommunications system having a central terminal and a plurality of subscriber terminals. , the communication between a central terminal and a subscriber terminal being arranged to occur via a wireless link, a plurality of multiplexed code division channels being provided within a single frequency channel to allow data elements in relation to a plurality of wireless links are transmitted simultaneously within different multiplexed code division channels of the frequency channel only, the method consisting of the steps of: (a) assigning a number of the plurality of multiplexed code division channels as a channel background multiplexed division of c codes available for the establishment of said wireless links; (b) using an analyzer to receive parameters in relation to a wireless link within the cell that indicates whether the wireless link is subject to interference of general signals by other cells and to compare those parameters with predetermined criteria; (c) generating an output signal that depends on the comparison in step (b); and (d) in response to the generated output signal, selectively reducing the number of multiplexed code division channels in the channel background in order to reduce the interference effect of the other cells.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention will be described hereinafter, by way of example only, with reference to the appended drawings, in which similar reference signs are used for similar characteristics and in which. Figure 1 is a schematic view of an example of a telecommunications system wireless in which an example of the present invention is included. Figure 2 is a schematic illustration of an example of a subscriber terminal of the telecommunications system of Figure 1. Figure 3 is a schematic illustration of an example of a central terminal of the telecommunications system of Figure 1. Figure 3A is a schematic illustration of a modem shelf of a central terminal of the telecommunications system of Figure 1.

Figure 4 is an illustration of an example of a frequency plane for the telecommunications system of Figure 1. Figures 5A and 5B are schematic diagrams illustrating possible configurations for cells for the telecommunications system of Figure 1. 6 is a schematic diagram illustrating aspects of a multiplexed code division system for the telecommunications system of FIG. 1. FIG. 7 is a schematic diagram illustrating the steps of signal transmission processing for the telecommunications system of FIG. Figure 1. Figure 8 is a schematic diagram illustrating the steps of signal reception processing for the telecommunications system of Figure 1. Figure 9 is a schematic diagram illustrating downlink and uplink communication paths for the radio system. wireless telecommunications. Fig. 10 is a schematic diagram illustrating the formation of a downward signal transmitted by the central terminal. Figure 11 is a graphic description illustrating the phase of adjustment to a slave code sequence of the subscriber terminal. Figure 12 is a graphic description of an estimate of signal quality performed by the receiver at the subscriber terminal.

Figure 13 is a graphical diagram illustrating the content of an information signal box within the downstream signal. Figure 14 is a tabular description illustrating the high insertion within a data stream of the downstream signal. Figure 15 is a schematic block diagram of a frame alignment circuit of an embodiment of the invention. 16A and 16B are time diagrams for explaining the operation of the frame alignment circuit of FIG. 15 and FIG. 16C is a state diagram of a state machine of the frame alignment circuit of FIG. 15. FIG. 17 is a graphic description of a transmission power and a transmission rate for each mode of operation of the wireless telecommunications system; and Figure 18 is a schematic diagram illustrating the operation of the receiver and transmitter at the subscriber's terminal.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 is a schematic overview of an example of a wireless telecommunications system. The telecommunications system includes one or more service areas 12, 14 and 16, each of which is served by a respective central terminal (CT) 10 which establishes a radio link with subscriber terminals (ST) 20 within the mentioned area. The area that is covered by a central terminal 10 may vary. For example, in a rural area with low subscriber density, a service area 12 could cover an area with a radius of 15-20 km. A service area 14 in an urban environment where there is a high density of subscriber terminals 20 could only cover an area with a radius in the order of 100m. In a suburban area with an intermediate density of subscriber terminals, a service area 16 could cover an area with a radius of the order of 1 km. It will be appreciated that the area covered by a particular central terminal 10 can be chosen to adjust local requirements for expected or actual density of subscribers, local geographic considerations, etc., and is not limited to the examples illustrated in Figure 1. More yet, coverage does not need to be, and typically it will not be circular in scope due to antenna design considerations, geographic factors, constructions and so on, which will affect the distribution of transmitted signals. The central terminals 10 for respective service areas 12, 14, 16 can be connected to each other by means of links 13, 15 and 17 that interact, for example, with a telephone network switched to the public 18 (PSTN). The links may include conventional telecommunications technology using copper wires, optical fibers, satellites, microwaves, etc. The wireless telecommunications system of Figure 1 is based on providing fixed microwave links between subscriber terminals 20 at fixed locations within a service area (eg, 12, 14, 16) and central terminal 10 for that area of service. service. Each subscriber terminal 20 may be provided with a permanent fixed access link to its central terminal 10, but in preferred embodiments access based on demand is provided, so that the number of subscribers that can be supported exceeds the number of subscribers. wireless links available. The way in which access based on demand is implemented will be described in detail later. Figure 2 includes a schematic representation of client building 22. Figures 2A and 2B illustrate an example of a configuration for a subscriber terminal 20 for the telecommunications system of Figure 1. A customer radio unit 24 (CRU ) is assembled by the client's property. The customer radio unit 24 includes a flat panel antenna or the like 23. The customer radio unit is mounted at a location by the customer's property, or by a post, etc., and in such an orientation that the flat panel antenna 23 within the customer radio unit 24 faces in the direction 26 of the central terminal 10 for the service area in which the customer radio unit 24 is located. The customer radio unit 24 is connected through a descent line 28 to a power supply unit 30 (PSU) within the customer's premises. The power supply unit 30 is connected to the local power supply to supply power to the customer radio unit 24 and a network terminal unit 32 (NTU). The customer radio unit 24 is also connected through the power supply unit 30 to the network terminal unit 32, which in turn is connected to the telecommunications equipment in the client's property, for example to one or more telephones 34, fax machines 36 and computers 38. The telecommunications equipment is represented as being inside a single client building . However, this need not be the case, since the subscriber terminal 20 preferably supports either a single line or a double line, so that two subscriber lines could be supported by a single subscriber terminal 20. The terminal of Subscriber 20 may also be arranged to support analog and digital telecommunications, for example analog communications at 16, 32 or 64 kbit / sec or digital communications in accordance with the ISDN BRA standard. Figure 3 is a schematic illustration of an example of a central terminal of the telecommunications system of Figure 1. The common equipment shelf 40 consists of a number of equipment shelves 42, 44, 46, including an RF combiner and a shelf for power amplifier 42 (RFC), a power supply shelf 44 (PS) and a number of modem shelves 46 (MS) (in this example 4). The combiner shelf RF (42) allows the modem shelves 46 to operate in parallel. If "n" modem shelves are provided, then the combiner shelf RF (42) combines and amplifies the energy of "n" transmission signals, each signal being transmitted from one of the respective "n" modem shelves, and amplifies and part the "n" signals received so that the separated signals can pass through the respective modem shelves. The power supply ledge 44 provides a connection to the local power supply and fuses it for the different components in the common equipment rack 40. A bidirectional connection extends between the ledge 42 of the RF combiner and the main center terminal antenna 52. , as an omnidirectional antenna, mounted by a central terminal mast 50. This example of a central terminal 10 is connected through a point-to-point microwave link to a location where an interface is made to the telephone network 18 switched to the public, shown schematically in figure 1. As mentioned above , other types of connections (e.g., copper wires or optical fibers) can be used to link the central terminal 10 to the telephone network 18 switched to the public. In this example the modem shelves are connected through lines 47 to a microwave terminal 48 (MT). A microwave link 49 extends from the microwave terminal 48 to an antenna 54 point-to-point microwave mounted by the post 50 for a host connection to the telephone network 18 switched to the public. A personal computer, workstation or the like can be provided as a site controller 56 (SC) to support the central terminal 10. The site controller 56 can be connected to each modem ledge of the central terminal 10 through, for example, RS232 connections (55). The site controller 56 can then provide support functions such as fault location, alarms and status and the configuration of the central terminal 10. A site controller 46 will typically support a single central terminal 10, although a plurality of site controllers 56 could be linked to support a plurality of central terminals 10. As an alternative to the RS232 connections (55), which extend to a site controller 56, the data connections as an X.25 link (57) (shown with lines dotted in Figure 3) could instead be provided from a pad 228 to a switch node 60 of a handler element 58 (EM). A handler element 58 can support a number of distributed central terminals 10 connected by respective connections to the switching node 60. The handler element 58 allows a potentially large number (eg, up to, or more than 1000) of central terminals 10 to be integrated within of a management network. The operating element 58 is based around a powerful work station 62 and may include a number of 64 computer terminals for network engineers and control personnel. Figure 3A illustrates various parts of a modem shelf 46. An RF unit transmitting / receiving (RFU- implemented for example by a card in the modem shelf) 66 generates the RF signals of modulated transmission at medium energy levels and recovers and amplifies the baseband RF signals for the subscriber terminals. The RF unit 66 is connected to an analogue card 68 (AN) which performs AD / DA conversions, baseband filtering and vector summation of 15 signals transmitted from the modem cards (MCs) 70. Analog unit 68 is connected to a number of 70 modem cards (typically 1-8). The modem cards perform the baseband signal processing of the signals transmitted and received to / from the subscriber terminals 20. This may include half speed convolution code and propagation x 16 with "code division multiplexed access" (CDMA) ) by the transmitted signals, and recovery of synchronization, de-propagation and error correction by the received signals. Each modem card 70 in the present example has two modems, and in preferred embodiments there are eight modem cards per shelf, and thus sixteen modems per shelf. However, in order to incorporate redundancy so that a modem can be substituted in a subscriber link when a failure occurs, only 15 modems through a single modem ledge 46 are generally used. The sixteenth modem is then used as a reserve that can be turned on if a failure of one of the other 15 modems occurs. The modem cards 70 are connected to the tributary unit 74 (TU) which terminates the connection to the public switched telephone host network (for example, through one of the lines 47) and manages the signaling of information of telephony to the subscriber terminals through one of 15 of the 16 modems. Wireless telecommunications between a central terminal and the subscriber terminals 20 could operate by several frequencies. Figure 4 illustrates a possible example of the frequencies that could be used. In the present example, the wireless telecommunication system is designed to operate in the 1.5-2.5GHz band. In particular the present example is designed to operate in the band defined by ITU-R (CCIR), Recommendation F.701 (2025-2110MHz, 2200-2290 Mhz). Figure 4 illustrates the frequencies used for the signal ascending from the subscriber terminals 20 to the central terminal 10 and for the signal descending from the central terminal 10 to the subscriber terminals 20. It will be noted that 12 radio channels amounting and 12 that descend each of 3.5MHz are provided centered around 2155MHz. The spacing between the transmission reception channels exceeds the minimum required spacing of 70MHz. In the present example, each modem shelf supports 1 frequency channel (i.e. a frequency that is higher than the corresponding decreasing frequency). Currently, in a wireless telecommunications system as described above, the CDMA encoding is used to support up to 15 subscriber links through a frequency channel (one subscriber link through each modem). Hence, if a central terminal has 4 modem shelves, it can support 60 subscriber links (15 x 4) (that is, 60 STs can be connected to a CT). However, it is becoming desirable that more than 60 STs are supported from a central terminal, and, in preferred embodiments of the present invention, improvements to the CDMA coding technique are provided to increase the number of subscriber links that can be supported. by a central terminal. Both the CDMA encoding, and the improvements made to the CDMA encoding according to preferred embodiments, will be described in more detail later. Typically the radio traffic of a particular central terminal will be extended within the area covered by a central terminal 10 neighborly. To avoid, or at least reduce the interference problems caused by adjacent areas, only a limited number of the available frequencies will be used by any given central terminal 10. Figure 5A illustrates a cellular-type arrangement of the frequencies to mitigate interference problems between adjacent central terminals. In the arrangement illustrated in Figure 5A, the shaded lines for the cells 76 illustrate a set of frequencies (FS) for the cells. Selecting three sets of frequencies (for example where FS1 = F1, F4, F7, F10, FS2 = F2, F5, F8, F11, FS3 = F3, F6, F9, F12), and arranging that the immediately adjacent cells do not use the same set of frequencies (see, for example, the arrangement shown in Fig. 5A), it is possible to provide an omnidirectional fixed assignment cell arrangement where interference between nearby cells can be reduced. The transmitter power of each central terminal 10 is preferably set so that the transmissions do not extend as far as the nearest cell that is using the same set of frequencies. Therefore, according to the arrangement illustrated in Figure 5A, each central terminal 10 can use the four frequency pairs (for the up and down signal, respectively) within its cell, each modem shelf in the central terminal 10 being associated with a respective RF channel (channel frequency pair). Figure 5B illustrates a cell-type arrangement that uses sectioned cells to mitigate problems between adjacent central terminals. As with Figure 5A, the different type of shaded lines in Figure 5B illustrates different frequency sets. As in Figure 5A, Figure 5B represents three frequency sets (for example, where FS1 = F1, F4, F7, F10, FS2 = F2, F5, F8, F11, FS3 = F3, F6, F9, F12) . However, in Figure 5B the cells are sectorized using a sectorized central terminal 13 (ST) which includes three central terminals 10, one for each sector S1, S2 and S3, with the transmissions for each of the three central terminals 10 being directed to the appropriate sector between S1, S2 and S3. This allows the number of subscribers per cell to increase threefold, while permanent fixed access is still provided for each subscriber terminal 20. Arrangements like those in Figures 5A and 5B can help to cause interference, but in order to ensure that cells operating on the same frequency do not inadvertently decode the data of others, a repeating pattern of seven cells is used in such a way that for a cell operating on a given frequency, all six adjacent cells operating through the The same frequency is assigned a unique code of random pseudo noise (PN). The use of PN codes will be discussed in more detail later. The use of different PN codes prevents neighborhood cells that work by the same frequency from inadvertently decoding the data of the others. As mentioned above, CDMA techniques can be used in a fixed allocation arrangement (ie, one in which each ST is assigned to a particular modem by a modem shelf) to allow each channel frequency to support 15 subscriber links . Figure 6 gives a schematic overview of coding and CDMA coding. In order to encode a CDMA signal, baseband signals, for example user signals for each respective subscriber link, are encoded at 80-80N within a baseband signal of 160k symbols / sec where each symbol represents 2 bits of data (see, for example, the signal represented in 81). This signal is then propagated by a factor of 16 using a propagation function 82-82N to generate signals at an effective chip rate of 2.56M symbols / sec at 3.5MHz. The propagation function involves applying a PN code (which is specified by a base per CT) to the signal, and also apply a Rademacher-Walsh (RW) code that ensures that the signals to respective subscriber terminals will be orthogonal to each other. Once this propagation function has been applied, the signals for respective subscriber links are then combined in step 84 and converted to radio frequency (RF) to give multiple user channel signals (eg 85) for transmission from the transmitting antenna 86.

During transmission, a transmitted signal will be subject to sources of interference 88, including external interference 89 and interference from other channels 90. Accordingly, at the moment when the signal CDMA is received on the receiving antenna 91, the multiple user channel signals may be distorted as shown at 93. In order to decode the signals for a given subscriber link from the received multiple user channel, a Walsh correlator 94 -94N uses the same RW and PN codes that were used for the encoding of each subscriber link to extract a signal (eg, as represented at 95) for the respective received baseband signal 96-96N. It will be noted that the received signal will include some residual noise. However, unwanted noise can be removed using a low pass filter and signal processing. The key to CDMA is the application of RW codes, these being a mathematical set of sequences that have the function of "orthonormality". In other words, if any RW code is multiplied by any other RW code, the results are 0. A set of 16 codes RW that can be used is illustrated in table 1 below: RWO 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 RW1 1-1 1-1 1-1 1-1 1-1 1-1 1-1 1-1 RW2 1 1-1-1 1 1-1-1 1 1-1-1 1 1-1-1 RW3 1-1-1 1 1-1-1 1 1-1-1 1 1-1-1 1 RW4 111 1-1-1- 1- RW5 1-11- -1-11-1 RW6 11-1 -1-1-11 RW7 1-1-1 1-111- RW8 11111 -1 -1 -1 - RW9 1-11 1-11- 1 RW10 11-1- 1-1 -11 RW11 1-1-1 • 1-111- RW12 111 -1111 RW13 1-11- 11-11- RW14 11-1- 111-1 RW15 1-1-1 - 11-1-1 TABLE 1 The above set of RW codes are orthogonal codes that allow multiple user signals to be transmitted and received by the same frequency at the same time. Once the bitstream is orthogonally isolated using the RW codes, the signals for the respective subscriber links do not interfere with each other. Because the RW codes are orthogonal, when they are perfectly aligned all codes have a cross-correlation of 0, thus making it possible to decode a signal while canceling the interference of users operating by other RW codes. In preferred embodiments of the present invention, it is desired to provide the central terminal with the ability to support more than 15 subscriber links per channel frequency, and to achieve this the previous set of 16 RW codes has been improved. In order to maintain compatibility with current products using the 16 RW codes, it was desirable that any improvement should retain the same set of 16 RW codes. The way in which the improvements have been implemented provides flexibility in how the frequency channels are configured, with certain configurations allowing a larger number of subscriber links to be supported, but at a lower raw bit rate . In preferred embodiments, a channel can be selected to operate with the following raw bit rates: 160 kb / s total speed (F1) 80 kb / s medium speed (H1, H2) 40 kb / s speed of a quarter (Q1, Q2, Q3, Q4) 10 kb / s low speed (L1, L2, L3, L4), for acquisition in elevation.

In preferred embodiments, the mode in which these pipelines are provided differs for the downlink (CT to ST) and upstream (ST to CT) communication paths. This is because it has been noted that different performance requirements exist for descending and ascending trajectories. By descending all the signals emanate from a single source, say the central terminal, and therefore the signals will be synchronized. However, by the upward path, the signals will emanate from a number of independent STs, and therefore the signals will not be synchronized. Given the previous considerations, in preferred modalities, through the total upward trajectory speed (160 kb / s) the operation is implemented using the basic set of RW codes discussed at the beginning, but the average and quarter speeds are achieved through the use of "superimposed codes" that consist of high speed RW code symbol patterns that are transmitted for each intermediate speed data symbol. For half-speed operation, two superimposed 2-bit codes are provided, while for quarter-speed operation, four codes are provided by four-bit stations. When a signal is generated for transmission, one of the superimposed codes, where appropriate, is applied to the signal in addition to the appropriate RW code. When the signal is received, then in the CDMA demodulator the incoming signal is multiplied by the PN, RW codes by means of stations of the channel. The integration period of the correlator is set to equal the length of the code throughput. Overlapping codes are extensively used to provide variable speed upstream traffic channels. The superimposed codes will also be used to implement downstream control channels, these control channels will be described in more detail later. However, as mentioned at the beginning, a different method is used to provide flexible channels through the downstream traffic channel courses. The downstream traffic channels will operate at high speed, in 160 kb / s mode with lower data rates of 80 and 40 kb / s being supported by "multiplexing time division" (TDM) the available bandwidth. In preferred embodiments, the time slot bit numbering TDM will follow the CCITT convention G.732 with bits transmitted in the bit 1 sequence, bit 2 bit 8. The bit orientation is specified per channel as being the most significant bit first (MSB), the least significant bit first (LSB) or N / A. The provision of a hybrid CDMA / TDM method for downstream traffic channels retains the benefits of CDMA access, ie the interference is reduced when traffic is reduced. In addition, the use of TDM ensures that the CDMA signal is limited to a 256 constellation of "Quadrature amplitude modulation" (QAM) which reduces the dynamic scale requirements of the receiver. The QAM constellations will be familiar to those skilled in the art. Through upstream channels, the pure CDMA method using overlapping codes eliminates the need to synchronize the STs time to a TDM reference frame. This has the advantage of eliminating TDM delays and "guard time" between TDM frames. Another benefit is reduced peak power management requirements in the ST RF transmitter chain which would otherwise be necessary when transmitting TDM data that is disrupting. The very dynamic scale requirement is restricted to the CT receiver. The manner in which the transmitted and received signals are processed in accordance with preferred embodiments in the present invention will be described with reference to FIGS. 7 and 8. FIG. 7A is a schematic diagram illustrating the steps of signal transmission processing as they are configured in a subscriber terminal 20 in the telecommunications system of Fig. 1. In Fig. 7A, an analogous signal from a telephone is passed through an interface as a two-wire interface 102 to a hybrid processing circuit 104. and then through an encoder-decoder 106 to produce a digital signal within which a raised channel including control information is inserted into 108. If the subscriber terminal supports a number of telephones or other telecommunications equipment, then the elements 102, 104 and 106 may be repeated for each piece of telecommunications equipment.

At the output of the high-insertion circuit 108, the signal will have a bit rate of either 160, 80 or 40 Kbits / s, depending on which channel has been selected for signal transmission. The resulting signal is then processed by a convolutional encoder 110 to produce two signals with the same bit rate as the input signal (collectively, these signals will have a symbol rate of 160, 80 or 40 KS / s). Next, the signals are passed to a propagator 111 where, if a reduced bit rate channel has been chosen, a suitable set code provided by the superimposed code generator 113 is applied to the signals. At the output of the propagator 111, the signals will be at 160 KS / s regardless of the bit rate of the input signal because the code throughput will have increased the symbol rate by the amount needed. The signal output from the propagator 111 is passed to a propagator 116 where the Rademacher-Walsh and PN codes are applied to the signals by a code generator RW (112) and a PN code generator (114), respectively. The resulting signals, at 2.56 MC / s (2.56 mega chips per second, where a chip is the smallest data element in a propagated sequence) are passed through a converter 118 from digital to analog. The digital-to-analog converter 118 forms the digital samples into an analogous waveform and provides a baseband power control stage. The signals are then passed to a low-pass filter 120 to be modulated in a modulator 112. The signal modulated from the modulator 122 is mixed with a signal generated by a voltage-controlled oscillator 126 that responds to a synthesizer 160. The output of the mixer 128 is then amplified in a low noise amplifier 130 before being passed through a bandpass filter 132. The output of the bandpass filter 132 is further amplified in an additional low noise amplifier 134, before of being passed to the power control circuitry 136. The output of the power control circuitry is further amplified in an energy amplifier 138 before being passed through an additional bandpass filter 140 and transmitted from the transmit antenna 142. FIG. 7B is a schematic diagram illustrating the steps of signal transmission processing as configured in a terminator. to central 10 in the telecommunications system of figure 1. As will be evident, the central terminal is configured to perform signal transmission processing similar to the subscriber terminal 20 illustrated in Figure 7A, but does not include the elements 100, 102, 104 and 106 associated with the telecommunications equipment. In addition, the central terminal includes a TDM encoder (105) to perform time division multiplexing where required. The central terminal will have a network interface by which incoming calls destined for a subscriber terminal are received. When an incoming call is received, the central terminal will contact the subscriber's terminal to which the call is directed and provide an appropriate channel through which the incoming call can be established with the subscriber's terminal (in preferred embodiments, this is done using the call control channel discussed in more detail later). The channel established for the call will determine the time slot to be used for call data passed from the CT to the ST and the TDM encoder (115) will be supplied with this information. Hence, when the data of the incoming call is passed from the network interface to the TDM encoder (105) via line 103, the TDM encoder will apply a suitable TDM encoding to allow the data to be inserted in the time slot. adequate Thereafter, the processing of the signal is the same as the equivalent processing performed in the ST and described with reference to FIG. 7A, the code generator throughput produces a single code by means of a value of "1" so that the output The signal from the propagator 111 is the same as the signal input to the propagator 111. As mentioned at the beginning, in preferred embodiments, the superimposed codes, rather than the TDM, are used to implement downstream control channels, and the data which relate to such channels are passed from a demand allocation engine (to be discussed in more detail later) via line 107 through switch 109 to high-pass circuit 108, sub passing therefore the TDM encoder (105). The processing of the signal is then the same as the equivalent processing performed in the ST, with the code generator by means of providing superimposed codes suitable for the propagator 111. The code generator by means of said code will be controlled so as to produce the code by means of a desired position, in preferred embodiments. , this control comes from the DA engine (to be discussed in more detail later). Figure 8A is a schematic diagram illustrating the signal reception processing steps as configured in a subscriber terminal 20 in the telecommunications system of Figure 1. In Figure 8A, the signals received in the receiving antenna 150 they are passed through a bandpass filter 152 before being amplified in a low noise amplifier 154. The output of the amplifier 154 is then passed through an additional bandpass filter 156 before being further amplified by an additional low noise amplifier 158. The output of the amplifier 158 is then passed to a mixer 164 where it is mixed with a signal generated by a controlled voltage oscillator 162 which responds to a synthesizer 160. The output of the mixer 164 is then passed through the L / Q modulator (166) and a low pass filter 168 before being passed to an analog-to-digital converter 170. The digital output of the converter 170 A / D at 2.56 MC / s is then passed to a correlator 178, to which the same Rademacher-Walsh and PN codes used during the transmission are applied by a generator 172 of RW code (corresponding to the generator code RW 112) and a PN code generator 174 (corresponding to a PN 114 code generator), respectively. The output of the correlator 178, at 160 KS / s, is then applied to the correlator 179, wherein no interposed code used in the transmission step to encode the signal is applied to the signal by the code generator through item 181. The items 170, 172, 174, 178, 179 and 181 form a CDMA demodulator. The output of the CDMA demodulator (in the cortor 179) is then at a rate of either 160, 80 or 40 KS / s, depending on the code by set applied by the cortor 179. The output of the cortor 179 is then applied to a decoder 180. Viterbi. The output of the Viterbi decoder 180 is then passed to a raised extractor 182 to extract the information from the raised channel. If the signal refers to call data, then the output from the overhead extractor 182 is then passed through the TDM decoder 183 to extract the call data from the particular time slot into which it was inserted by the CT TDM encoder ( 105). Then, the call data is passed through a codee 184 and a hybrid circuit 188 to an interface such as a two-wire interface 190, where the resulting analog signals are passed to a telephone 192. As mentioned in principle in tion to the ST transmission processing steps, the elements 184, 188, 190 may be repeated for each piece of telecommunications equipment 192 in the ST. If the data output by the raised extraction circuit 182 is data via a downstream control channel, then instead of passing that data to a piece of telecommunications equipment, a control logic 185 is passed through the switch 187. of call, where that data is interpreted by the ST. At the subscriber terminal 20, an automatic gain control stage is incorporated in the IF stage. The control signal is derived from the digital portion of the CDMA receiver using the output of a signal quality estimator. Figure 8B illustrates the signal reception processing steps as configured in a central terminal 10 in the telecommunications system of Figure 1. As will be evident from the figure, the signal processing steps between the RX antenna ( 150) and the raised extraction circuit 182 are like those within the ST discussed in connection with Figure 8A. However, in the case of the CT, the call data output from the high extraction circuit is passed through the line 189 to the network interface within the CT, although the control channel data is passed through the switch 191 to the DA motor (380) for processing. The DA engine is discussed in more detail later. The superimposed codes and the channeling planes are selected to ensure a signal orthogonality ie, in a suitably synchronized system, the contribution of all channels except the channel being demodulated add up to zero by the cortor integration period. In addition, the ascending energy is controlled to maintain a constant energy per bit. The exception to this is a low speed which will be transmitted to the same energy as a fourth speed signal. Table 2 below illustrates the superimposed codes used for full, half and quarter speed operations: TABLE 2 In preferred embodiments, a 10 kb / s acquisition mode is provided which uses concatenated overlays to form an acquisition method; this is illustrated in table 3 below: TABLE 3 Figures 9A and 9B are diagrams illustrating the ascending and descending delivery methods, respectively, when the system is fully loaded, and illustrate the difference between the use of superimposed codes illustrated in Figure 9A and the use of TDM as shown in FIG. lustra in Figure 9B. When overlapping codes are used, an RW code is split in the RW space domain to allow up to four subchannels to operate at the same time. In contrast, when using TDM, an RW code is split in the time domain, to allow up to four signals to be sent using an RW code, but at different times during the 125 us frame. As illustrated in Figures 9A and 9B, the last two codes RW, RW14 and RW15 are not used for data traffic in preferred modes, because they are reserved for call control and acquisition functions; this will be described in more detail later. The CDMA channel hierarchy is as illustrated in figure 10. Using this hierarchy, the following CDMA channels are possible: F1 H1 + H2 H1 + Q3 + Q4 H2 + Q1 + Q2 Q1 + Q2 + Q3 + Q4 Having described how CDMA codes are driven to allow flexible pipelines to be achieved, where bit rates can be reduced to allow more subscriber links to be managed per channel frequency, an overview of how the connection paths will be provided ascending and descending are established with reference to Figs. 11 and 12. Fig. 11 is a block diagram of downlink and uplink communication path between the central terminal 10 and the subscriber terminal 20. A downlink communication path is established from the transmitter 200 in the central terminal 10 to the receiver 202 in the subscriber terminal 20. A connection communication path Upstream is established from the transmitter 204 at the subscriber terminal 20 to the receiver 206 at the central terminal 10, Once the downlink and uplink paths have been established in the wireless telecommunication system 1, telephone communication can occur between a subscriber terminal user 208, 210 and a user receiving the service through the central terminal 10 on a downlink signal 212 and a rising signal 214. The downlink signal 212 is transmitted by the transmitter 200 of the central terminal 10 and is received by the receiver 202 of the subscriber terminal 20. The uplink signal 214 is transmitted by the transmitter 204 of the subscriber terminal 20 and is received by the receiver 206 of the central terminal 10. The receiver 206 and the transmitter 200 at the central terminal 10 are synchronized with each other with respect to time and phase, and are aligned at the information boundaries. In order to establish the downlink communication path, the receiver 202 in the subscriber terminal 20 must be synchronized with the transmitter 200 in the central terminal 10. The synchronization occurs through the development of a function of acquisition mode and a function of tracking mode in the downlink signal 212. Initially, the transmitter 200 of the central terminal 10 transmits the downlink signal 212. FIG. 12 shows the contents in the downlink signal 212. An information signal in frame 212 is combined with a downlink code. superposition 217 where appropriate, and the resulting signal 219 is combined with a code sequence signal 216 for the central terminal 10 to produce the downlink 212. The code sequence signal 216 is derived from a combination of a signal from noise code 220 pseudo-random and a code signal 222 Rademacher-Walsh. The downlink signal 212 is received at the receiver 212 of the subscriber terminal 20. The receiver 202 compares its phase and its code sequence with a phase and code sequence within the code sequence signal 216 of the downlink signal 212. The central terminal 10 is considered to have a master code sequence and the subscriber terminal 20 is considered to have a slave code sequence. The receiver 212 incrementally adjusts to the phase of its slave code sequence to recognize a coupling to the master code sequence and place the receiver 202 of the subscriber terminal 20 in phase with the transmitter 200 of the central terminal 10. The sequence of The slave code of the receiver 212 is not initially synchronized with the master code sequence of the transmitter 200 and the central terminal 10 due to the path delay between the central terminal 10 and the subscriber terminal 20. Such path delay is caused by the geographical separation between the subscriber terminal 20 and the central terminal 10 and other environmental and technical factors that affect the wireless transmission. After acquiring and starting the monitoring in the central terminal 10, the master code sequence of the code sequence signal 216 in the downlink signal 212, the receiver 202 enters a frame alignment mode to establish the downlink communication path. The receiver 202 analyzes the frame information within that of the frame information signal 218 of the downlink signal 212 to identify a start of the frame position for the downlink signal 212. Although the receiver 202 does not know at what point in the downstream signal information stream 212 has received the information, the receiver 212 must seek the start of the frame position in order to be able to process the information received from the transmitter 200 of the central terminal 10. Once the receiver 202 has identified another start of the the frame position, the downlink communication path has been established from the transmitter 200 of the central terminal to the receiver 202 of the subscriber terminal 20. The structure of the information radio frames sent in the downlink and uplink paths will be described with reference to FIGS. 13 and 14. In FIGS. 13 and 14, the following terms: Bn Client payload, 1 x 32 to 2 x 64 kb / s Dn Signaling channel, 2 to 16 kb / s OH Upper radio channel - 16 kb / s Traffic mode - 10 kb / s Mode acquisition / reserve Both figures 13A and 13B show a sub frame format 125us, which is repeated in a total radio frame, a frame typically lasts 4 milliseconds (ms). Figure 13A illustrates the radio frame structures, which are used in the preferred embodiments for the downward trajectory. The subframe (i) in Figure 13A shows the radio frame structure used for the low speed, 10 kb / s, acquisition mode (Ln-D) during which only the upper channel is transmitted. The subframe (ii) in Figure 13A shows the radio frame structure used for the call control channel operating at a quarter speed, 40 kb / s, mode (Qn-D), while the subframe (iii ) of Figure 13A illustrates the radio frame structure used for traffic channels operating at full speed, 160 kb / s, mode (F1-D). Similarly, the subframe (i) of FIG. 13B shows the radio frame structure used for the upstream path when operating at low speed acquisition or a call control mode (Ln-U). Subframes (ii) to (iv) show the radio frame structure used for traffic channels when operating at a quarter speed mode (Qn-U), medium speed mode (Hn-U), and mode total speed (F1-U), respectively.

Now considering the upper channel in more detail, Figures 14A and 14B show the upper frame structure employed for various information speeds. The upper channel may include a number of fields, a frame alignment word (FAW), a code synchronization signal (CS), a power control signal (PC), a maintenance operations channel signal (OMC) , a mixed WTO / D (HDLC) channel (OMC / D) signal, and a channel identifier byte (Ch.lD), and some unused fields. The word box alignment identifies the start of the box position for its corresponding information box. The code synchronization signal provides information for the control synchronization of the transmitter 204 at the subscriber terminal 20 to the receiver 206 at the central terminal 10. The power control signal provides information for controlling the transmission energy of the transmitter 204 in the subscriber terminal 20. The operations and maintenance channel signal provides status information regarding the downlink and uplink communication paths and a path from the central terminal to the subscriber terminal where the communication protocol also extends. operates on the modem shelf between the shelf controller and the modem cards. The OMC / D signal is a combination of the OMC signal and a signaling signal (D), while the Ch. ID signal is used to identify only one RW channel, said Ch. ID signal is used by the subscriber terminal for ensure that the correct channel has been acquired.

In the preferred embodiments, the subscriber terminal will receive the downstream traffic channel information at a rate of 160 kb / s.

Depending on the speed of channel B, the ST will be located in an appropriate part of the radio head. The following TDM representations are created: TABLE 4 In the previous table, the scheme used to identify a channel is the following. The speed code "F1" indicates the total speed, 160 kb / s, "D" indicates that the channel is a downstream channel, and "Tn / t" indicates that the channel is the multiple time division between the STs, "n "indicates the selected traffic time segment.

All the STs that operate in a traffic channel will receive the channel-D channel information at the speed of 16 kb / s. The D-channel protocol includes an address field to specify which ST is used to process the content of the message. The channel structure was illustrated above in Figures 9A and 9B. In the preferred embodiments, the channel structure is flexible but comprises: - At least one link acquisition channel (LAC) - At least one call control channel (CCC) -Typically priority traffic channels (PTC) -1 to 13 traffic channels (TC) The manner in which the pipeline is provided ensures that the above fixed signage provisions using the set of 16 RW codes described above are still supported, as well as the demand for access services that are available when a system is used according to the preferred embodiment. Figures 15A and 15B illustrate typical downstream and upstream channel structures that may occur in a loaded system according to the preferred embodiments of the present invention. As illustrated in Figure 15A, in the downward path, some signals can be found at 160 kb / s using a total RW channel. An example of such signals may be those sent in the fixed establishment links to products that do not support the CDMA pulses provided by the systems according to the preferred embodiments of the present invention, as illustrated by RW1 and RW2 in Figure 15A . Alternatively, a user may have authority to use an entire RW channel, for example when sending a fax, as illustrated by RW12 in Figure 15A. As illustrated by RW5 through RW11, the TDM can be used on downstream traffic channels to allow more than one CT to ST communication to be carried out on the same RW channel during each frame. In addition, as illustrated by RW3 and RW4, in the preferred embodiments certain channels can be secured to limit the interference of other nearby cells, as will be described in more detail below. Similar pipelines can be achieved for the ascending paths, but as illustrated in Figure 15B, the overlapping codes are used in place of the TDM to allow more than one ST to CT communication to be carried out on the same RW channel during each frame. (as shown in Figure 15B for RW5 to RW11). It should be noted that, in both Figures 15A and 15B, the channels RW14 and RW15 are reserved as a call control channel and a link acquisition channel, respectively, and the overlapping codes are used in said channels, without taking into account if the trajectory is an ascending or descending trajectory. Said two channels will be described in more detail below. The acquisition / network entry will be carried out through the link acquisition channel (LAC). After power-on, a ST will automatically attempt the downward acquisition of the LAC on a predetermined "home" RF channel. The LAC downstream channel (ie, RW15 in the preferred modes) will operate at 10 kb / s, total single user power. The descending acquisition will be simultaneous for all the STs. Each CT modem shelf will maintain a database that contains the serial numbers within the STs that could possibly be supported by the CT. The status of each ST will be registered with higher level states in the following way: free cold call_in_course Transition states will also be defined. An ST is considered cold if it has just been supplied, the CT has lost control communications with the ST or the CT has completed a cycle. With the LAC, the CT issues individual ST serial numbers and offers an invitation to acquire the uplink signal LAC. The cold ascending acquisition will be carried out in the low speed link acquisition channel. The CT will invite the specific STs to cold start through a control channel. Assuming an ascending channel is available, the appropriate acquisition overlay will be selected, and acquisition will begin. The "fast" firing of the descending RW channel can be supported at speeds other than Ln-D. Fast refers to that a coherent demodulation is maintained, and only convolutional decoding and the frame synchronization procedures need to be repeated. In the acquisition, the control information will be exchanged. The ST will be authorized and a short ST-identifier (between 12 and 16 bits) will be placed and used for the subsequent emissions. The ascending ST will operate long enough for the upstream signal to receive the parameters by the ST in terms of code phase and transmission power. These parameters will be used by the ST for subsequent hot start acquisitions and will also be maintained by the TC to allow the CT to force a cold ST for warm start. Upon successfully completing the network entry, the ST will be placed in the free state and instructed to stop the uplink communications and transfer to the call control channel (CCC) (RW14 in the preferred modes). The time taken for the network entry can be monitored and the following techniques can be used to reduce the network entry time if desired: (i) Prioritize, so that network access is first offered to them GOS users high (Degree of Service). (¡I) Convert traffic channels to LACs. (iii) In the case of a CT restart, invite the STs to attempt the warm upward start. A reduction in the network input time of a factor of 4 can be achieved. Said mechanism will need to be safeguarded against the possible deterioration of the parameters of warm upward start, that is, it can only be allowed as long as the related RF CT parameters do not have been modified. The CT will need to issue an ID to allow a ST to validate that the warm upward parameters were valid for that TC. (iv) Restart ST, the TC will save the copies of the warm start parameters of ST, so that a cold ST can have warm start parameters loaded in the acquisition invitation and then be instructed at warm start. After the network entry, all the STs listen to the CCC. Said channel issues the administration and call control information through a HDLC channel of 32 kb / s. In order to maintain communication management, the TC interrogates each ST in sequence. Each interrogation comprises an invitation to issue for a ST issued to acquire the ascending CCC followed by an information management exchange (authorization, ST alarm update, warm start parameters, ascending radio development information, etc.). Administration may fail due to any of the following reasons: (i) The ST has reduced energy or has been reduced. An EM alarm can be indicated if the above persists and the database so that the ST should be marked as cold. Immediately after, follow the network entry procedure. (ii) The ST is making a call or in the procedure of making a call. You can suspend the interrogation cycle and the management communications made in the appropriate traffic channel. When the administration interrogation s, it must be followed by a number of rapid interrogations until the ST responds or is cold. The CCC is required to transmit all copies of the invitations to acquire the LAC, so that an ST can be forced to acquire the ascending LAC.

Upstream acquisition procedure of traffic channel The basic procurement procedure of the lateral ST is as follows; (i) Turn on the ascending circuit (receiver) at a speed of 10 kb / s and select the appropriate traffic channel RW and superimposed codes. Acquisition of ascending CT is limited to achieving frame alignment. (ii) The ascending PC / CS channel will be decoded to create a busy / free indication. If the PC / CS reports busy, then it means that another ST is using that traffic channel and the ST aborts the acquisition procedure. (iii) Turn on the uplink signal at a rate of 10 kb / s, and select the appropriate RW traffic channel and overlapping codes.

Allow the ST transmitter to be at a nominal total speed energy level minus 18 dB. Although the PC / CS reports free, the ST will continue its fast ascending code search, passing the ascending energy level by +2 dB at the end of each search. The rising signal must acquire a nominal total speed energy minus 6 dB. Upstream acquisition is aborted if the maximum transmission level is reached and the PC / CS continues to report free. (iv) PC / CS reports busy. At this point the ST may have genuinely acquired the traffic channel, or instead may be observing that the PC / SC is busy because another ST has acquired the traffic channel. The ST sends an authentication request and responds with its ST-identifier. The CT guarantees upward access to return the ST-identifier. The ST aborts the acquisition procedure if the returned ST-identifier is not recognized (that is, it is not the ST-identifier that was sent). Said authentication procedure is arbitrary between the two STs that contend for the exit access and also prevents the STs from acquiring the TCs that have been reserved from the entry access.

Incoming call A number of TCs will be reserved for incoming calls, and the incoming call processing is as follows: (i) Verify the CT database - if the ST is in the current call status, the call will be denies. (ii) Verify that an ascending CT of the required bandwidth is available. If there is a bandwidth then a TC is reserved. (iii) An incoming call setup message is issued through the CCC to inform the ST of the incoming call and specify the TC on which the call is received. If the TC is not available but the TC is part of a service domain, then the incoming call reception message is sent with a null TC, otherwise the call is rejected. The service domains will be described in more detail later. The incoming call reception message is repeated a number of times. (iv) The ST tries the upward acquisition. The ST hears the downward signal and continues to attempt upward acquisition until the CT sends a message to the ST to return the ST to the CCC. The ST also runs a counter to return it to the CCC in the event that an incoming call is not completed. (v) In the successful ascending acquisition, the TC authenticates the ST. (vi) In the direction of speed originates from the CT modem.

A command is measured by the PC / CS to turn the signal down to the required bandwidth. The ST returns to the speed start command via the ascending PC / SC. The link is now of the required bandwidth.

Outgoing call Outgoing calls are supported by allowing slotted random access to TC up signals. The processing of the outgoing call is as follows: (i) The public CT "free list" of available traffic channels and priority traffic channels with their respective bandwidths. These lists are published periodically (in the preferred modalities, every 500 ms) and are used to mark the ascending access slots. (ii) An off-hook condition is detected by the ST. The ST initiates a call set-up counter. (iii) The ST waits for the following free list that will be received at the CCC. If the free list is empty, the outgoing call is blocked. The ST will generate a congestion tone. (iv) If the free list has available channels, the ST randomly selects a channel from the free list. The algorithm that the ST uses to select a channel will need to be specified in the free list. For example, it may be necessary for the ST to always select from a channel pool of minimum bandwidth so that the bandwidth channels remain available for high GOS users. Alternatively, the ST can select any channel independently of the bandwidth for minimum blocking. In the preferred modes, the STs will not select the low bandwidth channels and negotiate the rate increase. (v) The ST attempts the ascending acquisition in the specified TC, said procedure having been described previously. If the acquisition is successful then the outgoing call is processed. Otherwise, the ST returns to the CCC and waits for the next free list available. To avoid a number of STs attempting respectively to acquire the same TC, and to block each other, an appropriate protocol can be employed to govern the way in which the individual STs will act upon receiving the free list. (vi) The ST may not be able to acquire a TC for the time in which the call establishment counter expires. The ST can in such cases stop trying the outgoing access and generate the congestion tone.

Outgoing priority call It is recognized that the random access protocol used to establish normal outgoing calls can lead to blocking. In the preferred embodiments, access to a priority traffic channel is allowed, which is not blocked to a large extent. The priority call is complicated because the ST must: (i) Capture and decode the dialed digits, (¡i) The digits are regenerated when a blocking condition occurs. (Ii) Allow transparent network access in a non-blocking condition. (iv) Categorize all outgoing calls as priority or normal, so that normal calls are discarded in favor of priority calls. The priority call procedure in the preferred modalities is as follows: (i) The TC will publish directory numbers (DNs) for an emergency service number in the CCC. (ii) The ST will attempt upstream access according to the normal algorithms. If the outgoing access is successful then the client can dial as normal. All dialed digits are checked against the emergency DN list, so calls can be classified as normal or priority in the TC. (ni) If the congestion tone returns, the customer can dial the emergency number on the ST. If the ST detects an emergency DN sequence then upward access is attempted through the priority traffic channel (PCT). (iv) In the acquisition of the PTC, the ST is based on the digit sequence marked for the CT to mark in the PSTN. (v) The CT converts the PTC to a TC and embeds another TC to convert it to PTC, discarding a normal call in progress if necessary.

Interference limit (background size) In a large-scale cell deployment, optimal capacity is achieved by keeping radio traffic to a minimum while maintaining an acceptable degree of service. The lowest possible radio traffic results in improved "vehicle to interference" ratios (C / l) for users within the cell of interest and for co-channel users in nearby cells. The C / I ratio is a measure (usually expressed in dB) of how the previous high interference of the transmitted signal needs to be decoded effectively. In the preferred modalities, the central terminal is provided with the trade traffic capacity for C / l, thus allowing network planning to be carried out in a less rigid manner. Said feature can be carried out by a system using the CDMA as in the preferred embodiments of the present invention, and it is a benefit that the CDMA offers through the TDMA and FDMA systems. In the preferred embodiments, the CT will control the number of traffic channels to minimize access noise. The TCs are classified as: (i) Busy - carrier traffic; (¡I) Access, incoming (access_input), reserved for incoming access; (iii) Access, outgoing (outbound access) - reserved for outbound access - so that the TCs appear in the free list; (iv) Priority - reserved for outgoing priority access - so that the TCs appear in the free list. (v) Free - available for any purpose; and (vi) Blocked - not available due to limiting interference. Such a classification scheme is illustrated in Figure 16. The TC will place the traffic based on the following: (i) The TC will monitor the times of establishment of incoming and outgoing calls and will convert the access of TCs from the free TCs to achieve a required degree of service. (ii) When a call is established, a TC access is converted to a busy TC. If a free TC is available, it will be converted to a new TC access. If there are no free TCs then the TC access is lost until the call is cut off. (iii) When the call is cut off, the busy TC becomes a free TC. If a previous call establishment results in a lost TC access then the occupied TC becomes again a TC access. (iv) When the PTC is accessed, a new PTC is created by converting a free, Access or Busy TC (normal call). (v) The CT shall monitor the soft down and uphill error counts of busy CT in an attempt to establish link quality.

If the CT registers a soft error count below the average and the long call set-up times are being recorded, a locked TC can be converted to a free TC. Conversely, if the CT records a higher than average soft error count, a free or access TC can be converted to a blocked TC. Figure 17 illustrates how the central terminal performs the above interference limiting function. When the incoming call information arrives at a central terminal modem 320, the encoder 325 encodes the information for transmission on the wireless link 300 to the subscriber terminal 20. At the subscriber terminal 20, the decoder 326 decodes the information, and passes the decoded user information through line 328 to the subscriber's telecommunications equipment. As the decoder 326 decodes the information, it is possible to establish an estimate of bit error rate (BER) associated with the signal transmission on the wireless link 300, which can be passed to the multiplexer 332 to be combined with other signals, such as those of a call control function 336 or online user information 338, before going to a decoder 334. At this point, the BER estimate is decoded and passed through the OMC channel on the wireless link 310 to the decoder 340 within the mode at the central terminal 320. Once decoded by the decoder 340, the signal passes to the multiplexer 345, where the BER estimate of the subscriber terminal is detected and passed through the line 355 to the function of dynamic fundo size 360. Also, as in the subscriber terminal 20, the decoder 340 in the mold in the central terminal 320 can be set to a bit error rate estimate. 350 associated with the signal transmission on the wireless link 310. Said estimate of BER 350 also passes through line 355 to the dynamic background size function 360. The dynamic background size function 360 is provided on the shelf of CT modem 302, and receives the BER estimate of each of the modems of said ledge indicated by the lines that enter the bottom of the function of the dynamic background size 360. In addition to the BER estimates, the Service grade "GOS" is obtained from two sources. First, at each subscriber terminal 20, the call control function 336 will observe the ease of being able to establish traffic channels to transmit and receive information, and from the previous one a GOS estimate can be provided to the multiplexer 332 to be decoded. by the encoder 334 for subsequent transmission with the wireless link 310 to the central terminal modem 320. At this point, the GOS estimate is decoded by the decoder 340, passes through the multiplexer 345, and then the GOS estimate passes through the line 355 of the dynamic background size function 360. Additionally, the incoming call information to the central terminal, other than the call information of the subscriber terminal 20 connected to the central terminal, is provided through the concentrated network interface 390 to the DA 380 engine. The DA 380 engine includes a call control function , similar to the call control function 336 in each of the subscriber terminals 20, for each of the modems in the modem shelf. At this point, in a similar form of the call control function 336 at the subscriber terminals 20, the call control functions in the DA 380 engine can also provide GOS estimates for incoming calls, and said GOS estimates pass. through line 395 to the dynamic background size function 360. In the establishment, the management systems 370 in the element manager will have connected to the central terminal, and will have provided the function of dynamic background size 360 in the modem ledge with the information identifying a BER target, a GOS target and a background size limit (that is, the number of channels that can be used for information traffic). The dynamic background size function 360 then compares said management system information with the actual BER, real GOS, and the actual background size information it receives. A suitable algorithm can be provided in the dynamic background size function 360 to determine, based on said information, whether the background size is suitable. For example, if the actual bit error rate exceeds the target SEE provided by the management system 370, then the dynamic backfill function 360 may be arranged to send a request for the size of the fund to the demand allocation engine 380 The demand allocation engine 380 provides a modem that can send signals through lines 400 to each of the modems on the CT modem shelf. If the dynamic background size function 360 has required the DA 380 engine to perform a background size, then the DA 380 engine can disable one or more of the modems, thereby causing interference, and therefore that the real BER is reduced. In addition to being used to limit the interference, the DA engine is also responsible, in the preferred embodiments, for providing the coders 325 with instructions by which series of superimposed codes or how many TDM slots are to be used for the signals to be transmitted to STs. The dynamic background size function can store the BER and GOS information received in storage 365, and periodically can pass said information to the administration system 370 for analysis. In addition, if the system is not able to achieve the target BER or GOS with the assigned background size, the dynamic background size function can be arranged to place an alarm in the administration system. The reception of said alarm will indicate to the personnel using the administration system that manual intervention may be required to remedy the situation, that is, through the provision of other central terminal hardware to support the STs. The CDMA approach used in the preferred modes shows the property that the removal of any of the orthogonal channels (by disabling the modem) will improve the resistance of the other channels to interference. At this point, a suitable approach for the demand allocation engine 380, to receive the background size request of the dynamic size function 360, is to disable the modem that has the least traffic passing through it.

RF channel ignition In the preferred modalities, it has been observed that if an ST allows operating from more than one CT / RF channel modem shelf then the following benefits can be achieved: (i) Fault tolerance - if a fault occurs CT modem shelf subsystem an ST can turn on an alternate frequency for service. (ii) Call blocking - a denied ST service of a CT ledge may select to turn on an alternative frequency for service. (iii) Traffic load balancing - the element manager can, based on the call blocking statistics, select the movement of the STs between the CT shelves. (iv) Frequency diversity - in the presence of selective channel fading (slow multipath) an ST can operate on the frequency channel that offers superior signal strength and lower soft error count. RF channel ignition is only possible where there are two or more co-located CT shelves serving the same geographic area on different RF frequency channels within the same RF band. A deployment that meets these criteria can be configured as a "service domain". Possible deployment scenarios are illustrated in Figure 18. Figure 18 (i) shows an arrangement where the obnidirectional antennas are used to provide the total cell with four frequency channels, i.e. F1, F4, F7, F10. Figure (i) shows an arrangement where the sectioned antennas are used to provide six separate sectors in a cell, each sector being covered by two frequency channels. Figure 18 (iii) shows an alternative arrangement where three sectioned antennas are used to divide the cell into the three sectors, each sector being covered by a separate frequency channel, and then an obnidirectional antenna is used to provide an "umbrella" cover "for the total cell, said cover using a frequency channel different from the three frequency channels used by the sectioned antennas. In order for the system to work effectively, the STs must be able to turn on the channels quickly, and the rapid channel start-up requires the synchronization of the CT ledge to be provided at the following levels: (i) CDMA PN code. This code preserves the ascending code phase in the RF channels during warm start; and (ii) RF vehicle frequency. This frequency eliminates the need for the coarse frequency to seek a downstream RF channel ignition. In the installation, an ST will be programmed with an RF channel and a PN code, these codes specify the initial domestic channel of the ST. The manner in which channel ignition is facilitated in the preferred embodiments will be described with reference to Figures 19A and 19B. A service domain controller 400 is preferably provided to act as an interference between the exchange connected to the service domain controller in the path 405 and a terminal number and exchanges 10 connected to the service domain controller in the paths 410 The central terminals connected to the service domain controller form a "service domain" of terminal and exchanges that can be used by a subscriber terminal 20 for the control of communications. In the preferred embodiments, the service domain controller is used to provide each CT 10 with adequate information about the other CTs in the service domain. Each TC may then issue a "service domain" message comprising an RF frequency list and CT identifiers that form a service domain to be used by the CTs for the subsequent RF firing functions. The ST then stores that information for future reference when a link is established with one of the CTs. It is preferable for each TC to issue the service domain message, since an ST can be listed in any of the CTs at the time the message is issued. Each CT database contains one entry for each ST located in the service domain. Each database entry describes how the TC observes its relationship with the ST and can be marked as: (i) Primary service provider - the TC is the domestic channel of the STs. All management communication with a ST is done through your domestic CT.

(I) Provision of security service - the TC provides a service to the ST. (iii) Available for security service - the TC will provide the service to the ST if required. It should be noted that the ST does not need to turn on a completely different CT, from its place it can light a different CT ledge (and therefore a different RF frequency channel) in the same CT. However, in the preferred embodiments, the ST will typically fire with a different CT, although some errors experienced by a CT ledge may also affect other ledges within the same CT, and therefore for fault tolerance (described in more detail below), it is preferable for the ST to light a separate CT. The consistency of the database on CT shelves is preferably supported by the service domain controller.400. The consistency of the database needs to be in real time, so that a ST that enters the network can immediately have full access to the service domain (the service domain message is issued to all STs, and in this way a new ST will wait for access through the total service domain). Incoming access using security CTs requires that some function be provided to issue duplicate incoming call security messages to all CTs that make up a service domain. Preferably, the above is controlled by the service domain controller 400, which sends the incoming call set-up messages to each CT that operates in the service domain. All CTs will place the access access traffic channels and will delay the incoming call establishment message through the call control channel. If the upstream access is successful, a TC will respond to the service domain controller with an accepted call message, the other CTs will respond with the call setup messages with failure. Outbound access through a security CT is similar to normal outbound access. Another job that can be carried out by the service domain controller is to help the element manager 58 in the reconfiguration of the equipment in the case of a failure. For example, if a CT is taken out of commission because of a failure, a different TC can be put "online", and the service domain controller can provide the new CT with the necessary information about the other CTs in the service domain .. Figure 19B illustrates said elements of. the subscriber terminal used to implement the RF channel ignition. The radio subsystem 420, which incorporates the transmit and receive signal processing steps, will pass any information received in the call control channel on line 425 to the message decoder 430. If the decoder 430 determines that the information in the call control channel it forms a service domain message, then it passes through line 435 to the channel selection controller 440, wherein the information within the service domain message is stored in storage 445. Similarly, if the message decoder identifies the information as "a free list", identifying the available traffic channels at a particular RF frequency, then that information is passed to the call control function 336 and the controller selects the channel 440 through path 450. The call control function 336 stores the free list in the storage 445 for the u or subsequent by the call control function 336 and the channel selection controller 440. If the message decoder 430 determines that the information forms an incoming call set-up message, then that information is supplied on line 455 for the function call control 336 and the channel selection controller 440 for processing. The incoming call setup message typically specifies a TC on the current frequency channel that should be used to access the incoming call, and the channel selection controller will attempt to establish a link on said TC. The channel selection controller will instruct in such cases the radio subsystem 420 on line 465 to use the current frequency channel to establish the required link. On the other hand, if the traffic channel specified in the call setup message is "null" the channel selection controller has the option to change the RF frequency using the information stored in the storage 445 about the other CTs in the service domain. To allow the controller that the selection controller 440 receives the information about the state of links, a link operation status signal may be supplied through line 470 from the radio subsystem. This signal will give an indication of the radio link quality, and may be a simple "OK" or "fail" indication, or alternatively may include extra information such as the BER values for the link. Said information can be used by the channel selection controller to determine whether or not a particular frequency channel should be used. To allow the call control function to specify a specific access_output channel for outgoing calls, a line 460 is provided between the call control function 336 and the channel selection controller.440. The call control function 336 may select an output access channel from the free list in the storage 445 and instruct the channel selection controller through the line 460 to attempt the acquisition of said channel. The following examples indicate how the structure described above can be used to carry out the channel ignition in particular circumstances.

RF channel ignition for fault tolerance If an RF channel suffers complete loss of the downlink signal, the following procedure takes place in the preferred modes: (i) The ST will attempt to reacquire the downlink signal for a period of 20 seconds. (ii) If the acquisition fails, the channel selection controller 440 of the ST will select the next available channel of service domain information in storage 445 and will try to acquire the downstream signal. Said procedure will be repeated until the downward signal is acquired. (iii) Once the security RF channel is located, the ST "will wait" on the call control channel and may subsequently be in the granted traffic access. (V) If the CT failure persists, EM 58 may use the service domain controller 400 to reconfigure the service domain so that the operating CT ledges become primary service providers for the STs pool. " destitute". A failure that does not result in the complete loss of the downstream signal will not result in the "mass" RF channel turning on. Instead, a failure can result in excessive or total call blocking, as described below.

Switching on the RF channel for call blocking If the incoming access traffic channels are blocked, the following procedure is used in the preferred modes: (i) The call set-up message sent through the call control channel will specify a TC in which to access the call. (ii) In the event that incoming access is blocked, the TC will specify a null TC. The channel selection controller 440 of the ST will in these cases change to the next RF channel from the service domain information in the storage 445 and monitor the call control channel. (iii) If the ST receives a call setup message with a valid TC, then the call is processed as normal. (iv) When the call is cut, the downward signal ST preferably changes back to home CT. If the outgoing access traffic channels are blocked, the following procedure is used in the preferred modes. (i) The ST registers a hanging. The free list in the storage 445 is verified and if a traffic channel is available then the call control function 336 secures an online channel request 460 to the channel selection controller 440 and normal upstream access is attempted. (ii) If the free list does not show available access_out channels in the current frequency channel, then the channel selection controller will be used to change the ST to the next RF channel in the service domain, where the ST will wait by the following free list. (iii) When the ST finds a free list with an available access_out channel, then the upstream access is attempted and the call is processed as normal. (iv) When the call is cut off, the downward signal ST preferably changes back to the domestic CT.

Change of RF channel for the traffic load balance The traffic load balance, in the preferred modes, is provided by the static configuration through EM 58. The call blocking and the establishment time statistics can be distributed to the EM where an operator can decide the movement of one ST to another RF channel.

Change of RF channel for frequency diversity. The frequency diversity, in the preferred embodiments, is provided with the static configuration through EM 58. The radio link statistics can be distributed to the EM where an operator can decide the movement of one ST to another RF channel. Although a particular embodiment has been described herein, it will be appreciated that the invention is not limited thereto and that various modifications and additions may be made thereto within the scope of the invention. For example, various combinations of the features of the following dependent claims may be made with the features of the independent claims without departing from the scope of the present invention.

Claims (28)

NOVELTY OF THE INVENTION CLAIMS

1. - An interference controller for limiting in one cell the interference effect generated by another cell of a wireless telecommunication system, each wireless telecommunication system cell having a central terminal and a plurality of subscriber terminals, communication between a central terminal and a subscriber terminal being arranged to occur in a wireless link, a plurality of multiplexed code division channels being provided with a single frequency channel to allow the data elements belonging to a plurality of wireless links to be transmitted simultaneously within the multiplexed channels of code division different from said single frequency channel, the interference controller containing: a channel controller arranged to place a number of said plurality of multiplexed code division channels as a multiplex channel division channel background available for the establishment of such wireless links; An analyzer for receiving parameters belonging to a wireless link within the indicative cell if the wireless link is subject to interference of the signals generated by said other cells; the analyzer being arranged to compare said parameters with the predetermined criteria, and to generate a dependent output signal in the comparison; and the channel controller being responsible for the output signal from the analyzer to selectively reduce the number of code division multiplexed channels in the channel bottom to reduce the interference effect of said other cells.

2. An interference controller according to claim 1, further characterized in that a parameter provided to the analyzer is the bit error rate (BER) for signals transmitted within said multiplexed code division channels, and the predetermined criteria with which the analyzer compares said BER is an input BER value that identifies a predetermined maximum acceptable BER, the channel controller being responsible for the analyzer indicating that the BER exceeds the predetermined maximum acceptable BER to remove a multiplexed code division channel from the channel bottom.

3. - An interference controller according to claim 1 or claim 2, further characterized in that a parameter provided to the analyzer is a signal indicative of service grade (GOS) of the availability of multiplexed code division channels, and predetermined criteria with which the analyzer compares said GOS signal is an input GOS value that identifies a predetermined maximum service degree, the channel controller being responsible for the analyzer indicating that the GOS signal has exceeded the maximum service degree default to remove a multiplexed division channel from the channel bottom.

4. - An interference controller according to any of the preceding claims, further characterized in that the channel controller, upon receiving a signal from the analyzer indicating that a multiplexed code division channel must be removed from use, is arranged to determine that the multiplexed code division channel is used less frequently, and to remove said multiplexed code division channel from the channel bottom.

5. - An interference controller according to any of the preceding claims, further characterized in that a plurality of the multiplexed code division channels are designed as traffic channels, the analyzer is arranged to monitor the parameters that are related to the interference in said traffic channels, and the channel controller is arranged to selectively designate one more of said traffic channels as blocked channels that should not be included in the channel fund, to reduce the interference effect of said other cells.

6. An interference controller according to claim 5, further characterized in that if the analyzer determines that the BER signal is below a predetermined minimum BER value, the channel controller is arranged to designate one of said blocked channels as a free traffic channel, and to include said traffic channel in the channel fund so that it can be subsequently used for information traffic.

7. - An interference controller according to claim 5 or claim 6, further characterized in that the analyzer determines that the GOS signal has fallen below a second predetermined minimum GOS value, the channel controller is arranged to designate one of said blocked channels as a free traffic channel, and to include said traffic channel in the channel fund so that it can be subsequently used for information traffic.

8. - An interference controller according to any of claims 5 to 7, further characterized in that the channel controller is provided with a value indicating a maximum number of multiplexed code division channels that can be designated as traffic channels , the channel controller only adds the multiplexed code division channels at the request of the analyzer, if doing so does not exceed the maximum number of multiplexed code division channels.

9. An interference controller according to any of claims 5 to 8, further characterized in that a number of the traffic channels are reserved as call channels, and a number of the traffic channels are designated as free channels, and if a call channel is used to pass call information, the channel controller is arranged to designate a free channel as a call channel if a free channel is available, thereby improving the timing of a call channel by being available for a subsequent call.

10. An interference controller according to any of the preceding claims, further characterized in that said multiplexed code division channels are orthogonal channels, a series of orthogonal codes used to create said orthogonal channels.

11.- A central terminal for a cell of a wireless telecommunication system, the telecommunications system having a plurality of cells and each cell having a central terminal and a plurality of subscriber terminals, the communication between the central terminal and the terminal of subscriber in said cell being arranged to occur in a wireless link, a plurality of multiplexed code division channels being provided within a single frequency channel to allow data elements belonging to a plurality of wireless links to be simultaneously transmitted within different multiplexed code division channels of said single frequency channel, the central terminal comprising an interference controller according to any of the preceding claims for limiting the interference effect generated by another cell of said wireless telecommunication system.

12. - A central terminal according to claim 11, further comprising: an orthogonal code generator for providing an orthogonal code from a series of orthogonal codes used to create said multiplexed code division channels within the single frequency channel; a first encoder for combining a data element to be transmitted in the single frequency channel with said orthogonal code from the orthogonal code generator, the orthogonal code determining the multiplexed code division channel with which the data element is transmitted, enabling in this way that the data elements belonging to different wireless links are transmitted simultaneously within different multiplexed code division channels of said single frequency channel.

13. A wireless telecommunication system, comprising a plurality of cells and each cell having a central terminal and a plurality of subscriber terminals, communication between a central terminal and the subscriber terminal within a cell arranged to occur through a wireless link, a plurality of multiplexed code division channels being provided within a single frequency channel to allow data elements belonging to a plurality of wireless links to be transmitted simultaneously within multiplexed code division channels different from one another. said single frequency channel, at least one cell of the wireless telecommunication system comprising an interference controller according to any of claims 1 to 10 for limiting the interference effect generated by another cell of said wireless telecommunication system.

14. An interference controller according to any of claims 1 to 10, further comprising a transmission controller for processing the data elements to be transmitted through a wireless link that is connected to a central terminal and a subscriber terminal of a wireless telecommunication system, employing a single frequency channel for transmitting training elements belonging to a plurality of wireless links, the transmission controller comprising: an orthogonal code generator for providing an orthogonal code of a series of orthogonal codes "m" used to create orthogonal channels "m" within the single frequency channel; a first encoder for combining a training element to be transmitted in the single frequency channel with said orthogonal code from the orthogonal code generator, the orthogonal code determining the orthogonal channel in which the data element is transmitted, wherein the elements of data belonging to different wireless links can be transmitted simultaneously within the orthogonal channels different from said single frequency channel; a code generator put together to provide a code by means of a position from a first series of code through position "n" that are orthogonal to each other; and a second encoder arranged to apply the code by placing it from the code generator by means of the said data element, wherein the data elements "n" belonging to different wireless links can be transmitted simultaneously within the same orthogonal channel.

15. An interference controller according to any of claims 1 to 10, further comprising a receiving controller for processing the data elements received in a wireless link that is connected to a central terminal and a subscriber terminal of a wireless telecommunication system, using a single frequency channel to transmit the training elements belonging to a plurality of wireless links, the receiver controller containing: an orthogonal code generator, to provide an orthogonal code and a series of orthogonal codes " m "used to create orthogonal channels" m "within the single frequency channel; a first decoder for applying, to the signals received in the single frequency channel, the orthogonal code provided by the orthogonal code generator, for isolating the transmitted data elements within the corresponding orthogonal channel; a code generator set to provide a code by placing from a first series of superimposed codes "n" that are orthogonal to each other, the series of overlapping codes "n" allowing the data elements "n" belonging to the different links wireless is transmitted simultaneously within the same orthogonal channel; and a second encoder to apply, to the data elements of the orthogonal channel, the code by being set from the code generator by means of an array to isolate a particular data element transmitted using the code by means of the code.

16. An interference controller according to any of claims 1 to 10, further comprising a transmission controller for processing the data elements to be transmitted on a wireless link connecting a central terminal and a subscriber terminal of a wireless telecommunication system employing a single frequency channel to transmit the data elements belonging to a plurality of wireless links, the transmission controller containing: an orthogonal code generator to provide an orthogonal code of a series of orthogonal codes "m "used to create orthogonal channels" m "within the single frequency channel; a first encoder for combining a data element to be transmitted in the single frequency channel with said orthogonal code from the orthogonal code generator, the orthogonal code determines the orthogonal channel in which it is transmitted in data element, wherein the elements of data belonging to different wireless links can be transmitted simultaneously within different orthogonal channels of said single frequency channel; and a TDM encoder arranged to apply time division multiplexing TDM techniques to the information feed for the purpose of inserting the data element into the time slot of the orthogonal channel, wherein a plurality of data element is related to with different wireless links it can be transmitted within the same orthogonal channel during a predetermined frame period.

17. An interference controller according to any of claims 1 to 10, further comprising a receiving controller for processing the data elements received in a wireless link connecting a central terminal and a subscriber terminal of a system of wireless telecommunications, using a single frequency channel to transmit the data elements belonging to a plurality of wireless links, and orthogonal channels "m" providing within the single frequency channel, the receiver controller containing: an orthogonal code generator for providing an orthogonal code of a series of orthogonal codes "m" used to create said orthogonal channels "m" within the single frequency channel; a first decoder for applying, to the signals received in the single frequency channel, the orthogonal code provided by the orthogonal code generator, for the purpose of isolating the transmitted data elements within the corresponding orthogonal channel; and a TDM decoder arranged to extract a data element from a predetermined time slot within said orthogonal channel, a plurality of data elements that relate to different wireless links that are transmitted within the same orthogonal channel during the predetermined frame period .

18. An interference controller according to any of claims 1 to 10, or 14 to 17, further comprising a channel selection controller for establishing a wireless link connecting a central terminal and a subscriber terminal of a system of wireless telecommunications, providing at least two frequency channels in which said wireless link could be established, the channel controller containing: a storage to store the information identifying at least two frequency channels; a selector for selecting a frequency channel from said channels listed in said storage; the acquisition of a logical link to establish a wireless link in the frequency channel selected by the selector; the selector being responsible for the acquisition of logical link, being unable to establish said wireless link, to select an alternative frequency channel from said channels listed in said storage.

19. A method for limiting in a cell the effect of interference generated by other cells of a wireless telecommunication system, each cell of the wireless telecommunication system having a central terminal and a plurality of subscriber terminals, communication between a terminal central and a subscriber terminal being arranged to occur in a wireless link, a plurality of multiplexed code division channels being provided within a single frequency channel to allow the data elements belonging to a plurality of wireless links to be transmitted simultaneously within of different multiplexed code division channels of said single frequency channel, the method comprising the steps of: a) placing a number of said plurality of multiplexed code division channels as a pool of multiplexed code division channels available for the establishment of said e wireless links; b) employing an analyzer to receive parameters belonging to a wireless link within the indicative cell if the wireless link is subjected to interference of the signals generated by said other cells and to compare said parameters with the predetermined criteria; c) generating a dependent output signal compared to said step b); and d) responding to the generated output signal, selectively reducing the number of code division multiplexed channels in the channel background in order to reduce the interference effect of said other cells.

20. A method according to claim 19, further comprising the steps of: providing the analyzer with an identification parameter of the bit error rate (BER) for signals transmitted within said multiplexed code division channels; supplying in accordance with the predetermined criteria with which the analyzer is compared said BER an input BER value that identifies a predetermined maximum acceptable BER; and if the generated output signal indicates that the BER exceeds the predetermined maximum acceptable BER, then in said step d) removing a multiplexed code division channel from the channel bottom.

21. - A method according to claim 19 or claim 20, further comprising the steps of: providing the analyzer with a parameter that identifies a signal indicative of grade of service (GOS) of the availability of multiplexed code division channels; supplying in accordance with the predetermined criteria with which the analyzer of said GOS signal is compared an input GOS value that identifies a predetermined minimum degree of service; and if the generated output signal indicates that the GOS signal has fallen below the predetermined minimum service degree, then in said step d) removing a multiplexed code division channel from the channel bottom.

22. A method according to any of claims 19 to 21, further characterized in that if the generated output signal indicates that a multiplexed code division channel must be removed from use, then in said step d) which channel is determined code division multiplexing is used less frequently, and which code division multiplexing channel is removed from the channel pool.

23. A method according to any of claims 19 to 22, further characterized in that a plurality of multiplexed code division channels are designated as traffic channels, the analyzer arranging to the monitor the parameters that are related to the interference in said traffic channels, and in step d) the method containing the steps of selectively designating one or more of said traffic channels as blocking channels that should not be included in the channel background, to reduce the effect of the interference of said channels. other cells.

24. A method according to claim 23, further comprising the steps of: receiving a number of the traffic channels as call channels; designate a number of traffic channels as free channels; and if a call channel is used to pass the call information, designate a free channel as a call channel if it is available to a free channel, thereby improving the opportunity of a call channel being available for a subsequent call.

25. An interference controller according to claim 1, substantially as described above with reference to the accompanying drawings.

26. A central terminal according to claim 11, described substantially as above with reference to the accompanying drawings.

27. A wireless telecommunication system according to claim 13, described substantially as above with reference to the attached drawings.

28. A method for limiting in a cell the interference effect generated by other cells of a wireless telecommunication system in accordance with claim 19, described substantially as above with reference to the accompanying drawings. APPENDIX SHEET SUMMARY OF THE INVENTION The present invention provides a controller and transmission method for processing the data elements to be transmitted through a wireless link connecting a central terminal and a subscriber terminal of a wireless telecommunications system, using a single frequency channel for transmitting the data elements belonging to a plurality of wireless links; the transmission controller comprises an orthogonal code generator for providing an orthogonal code of a series of orthogonal codes "m" used to create orthogonal channels "m" within the single frequency channel, and a first encoder for combining a data element that The orthogonal code is to be transmitted in the single frequency channel with said orthogonal code from the orthogonal code generator, the orthogonal code determining the orthogonal channel in which the data element is transmitted, wherein the data elements belonging to different wireless links can be transmitted simultaneously within different orthogonal channels of said single frequency channel; furthermore, the transmission controller comprises a code generator by means of a post to provide a code by means of a first series of overlapping codes "n" that are orthogonal to each other, and a second codec arranged to apply the code by means of the generator set. code by way of said data element, wherein the data elements "n" belonging to different wireless links can be transmitted simultaneously within the same orthogonal channel; The invention also provides a controller and reception method for processing the data elements received in a wireless link. P99-731 F