MXPA00004755A - Methods and systems of performing system channel planning for wireless local loop communication - Google Patents

Abstract

Methods and systems of communication reduce the internal interference associated with conducting radio communication in a wireless local loop communication system down to acceptable levels. Problems associated with internal interference are solved by providing carrier frequency rotation during time slots in a frame. A plurality of radio fixed parts are utilized for conducting radio communication with user terminals. During operation, each of a plurality of sequentially related carrier frequencies is assigned in sequential order to a respective one of the plurality of radio fixed parts. Each of the plurality of carrier frequencies is advanced during each successive time slot during operation of the wireless system. In addition, the control system controls operation of the radio fixed parts by allowing and disallowing transmission and reception in certain predetermined time slots.

Description

METHODS AND SYSTEMS REALIZATION SYSTEM CHANNEL PLANNING FOR WIRELESS LOCAL LOOP COMMUNICATION FIELD OF THE INVENTION The present invention relates to a novel method of communication for wireless local loop communication systems and, more particularly, the present invention relates to methods and systems for rotation of carrier frequencies during radio transmission and reception between a radio access node and a user terminal to minimize problems of internal interference and blocking. BACKGROUND OF THE INVENTION Cellular systems operate according to the principle of frequency reuse that provides a cellular operator the ability to offer a high radio traffic capacity. With higher radio traffic capacity, more users per geographical area can use a radio communication. Frequency reuse, which is a central concept in cellular communication, includes the reuse of the same frequency in a system many times to handle multiple calls. Time division multiple access ("TDMA") is a form of access technology that allows multiple users to occupy the same frequency spectrum. Each user of the cellular system shares the assignment of frequencies with other users who have assignment of time segments during other periods.

In a wireless local loop communication system that employs the TDMA standard of cellular communication, many users share the same frequency channel, each user receiving a single time segment. As the traffic within each random access node or cell site increases, the level of internal interference and signaling of the blog rises due to the fact that the number of carriers in use in neighboring fixed radio parts rises. When a fixed access unit, or mobile station, is making a call, the user will suffer from quality problems since several factors affect the quality of a radio communication such as, for example, internal interference, blocking, loading, propagation of multiple trajectories, dispersion and reflection. Previous attempts were made to reduce such problems associated with the quality of the calls. Previous low level PCS communication systems have attempted to solve the problem of internal system interference and blocking by using dynamic channel allocation. In order to maintain the quality of radio communication within the cellular network, a fixed access unit, or mobile unit, explores the operating environment and selects all available channels. The result of the scan is then loaded into a history table in the order of its quality. The history table is updated at different time intervals to constantly monitor the condition of the various channels available for use. If a telephone or a mobile unit begins to present interference, fading, or receives a stronger signal from another base station during the call, the mobile unit automatically connects to a better channel based on the information loaded in the history table. In a wireless local loop communication system, the distance between a random access node and a fixed access unit is much greater than the range of operation of a wireless business system. A radio access node and a fixed access unit can be up to 3,000 meters away while in a wireless business system, the radio access node fixed access units are usually at a maximum of 300 meters away. The local channel condition can be quite different for a fixed access unit in these two systems due to the interference and blocking problems experienced by a fixed part of the radio. A channel detected by the fixed access unit as a good channel may turn out to be a bad channel for a fixed part of the radio. A dynamic channel allocation system does not indicate the difference in channel quality and, therefore, it will not effectively solve the problems associated with internal interference and blocking. As a result of this problem. The capacity of the cellular system deteriorates dramatically as traffic increases. Accordingly, there is a need for a system channel planning method that will effectively solve the problems associated with internal interference and the block in a wireless local loop communication system. SUMMARY OF THE INVENTION The present invention solves the problems associated with internal interference and blocking by providing a carrier planning method for wireless local loop communication systems. The invention comprises a communication method for wireless local loop communication systems. In the invention, several fixed parts of radio are used to form a set, which is known as a radio access node. In addition, several sequentially related carrier frequencies are provided to carry out radio communication. Each of the various carrier frequencies is divided into a series of frames, the frames are made up of several time segments. In the operation, each of the sequentially related carrier frequencies is assigned in sequential order to a respective part of the radio-fixed fixed parts in each of the time segments. Each of the several sequentially related carrier frequencies is advanced each successive time segment by a predetermined number of carrier frequencies. The last carrier frequency of several sequentially related carrier frequencies is followed by the first carrier frequency. In order to further reduce the internal interference, during operation, each of the several sequentially related carrier frequencies is assigned in such a way that no fixed part of adjacent radio in the set is using the same carrier frequency in a segment of given time. The method further comprises the step of dividing each of the frames into a first set of time segments and into a second set of time segments. The wireless local loop communication may then not allow radio reception in the odd numbered radio-set fixed parts and may not simultaneously allow radio transmission in the evenly numbered radio-numbered fixed parts during the first set of radio frequencies. time segments. In the same way, the wireless local loop communication system may not allow radio transmission in the evenly numbered radio-controlled fixed parts and not to allow radio reception in the radio-numbered fixed parts evenly numbered during the second set of time segments.

The present invention also offers a wireless local loop communication system. The wireless local loop communication system has several fixed radio-controlled parts employing several sequentially related carrier frequencies to carry out radio communication with user terminals. Each of the carrier frequencies sequentially related is divided into a series of frames, which are formed of several time segments. A control unit is connected to the various fixed radio-graduated parts to assign each of the carrier frequencies sequentially related to a respective part of the various fixed radio parts set in sequential order in each of the time segments. During operation, the control unit scales each of the sequentially related carrier frequencies during each successive time segment by advancing the various carrier frequencies sequentially related to a predetermined number of carrier frequencies in each of the fixed portions of the carrier. radio graduated. The last carrier frequency of the series of sequentially related carrier frequencies is replaced by the first carrier frequency. In the preferred embodiment, the carrier frequencies are graded by a carrier frequency. In addition, to further minimize the internal interference, the sequentially related carrier frequencies are assigned such that no fixed part of adjacent graded radio receives the same carrier frequency when the number of fixed parts of graded radius exceeds the number of carrier frequencies. related sequentially. The wireless communication system may also divide the frames into a first set of time segments and a second set of time segments. The control unit then does not allow radio reception in the fixed radio parts with odd numeration and may also not allow radio transmission in the radio-graduated fine parts in the radio-fixed parts with numbering during the first segment of time. In addition, the control unit may not allow radio transmission in the fixed radio parts with odd numeration and may not allow radio reception in the fixed radio parts with even numbering during the second time segment. Other features and advantages of the invention will be apparent from the drawings and from the more detailed description of the invention presented below. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a diagrammatic representation of a preferred embodiment of a wireless local loop communication system. Figure IA is a diagrammatic representation of a radio access node having six fixed radio parts. Figure IB is a diagrammatic representation of a set of radio access nodes. Figure 2 is a diagrammatic decomposition of a series of time segments that is employed in TDMA type radio communication. Figure 3 is a diagrammatic illustration of a time segment. Figure 4 is a illustrates the carrier frequency assignment for a RAN that has six fixed radio parts. Figure 5 illustrates the assignment of carrier frequencies for a RAN that has twelve fixed radio parts. DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a novel system carrier frequency planning method in a wireless local loop communication system that maintains internal radio interference and blocking at acceptable levels. This method offers higher quality, flexibility and capacity in wireless local loop networks thus solving the problems associated with the prior art. Since the present invention comprises methods and systems for optimally operating multichannel wireless local loop communication systemsIt is important to have a basic understanding of how such wireless local loop communication systems operate. A wireless local loop communication system may vary from location to location, depending on the needs of the system. For example, a wireless local loop communication system used in a rural environment is different from those used in an urban area with high population density. The present invention offers a method of system operation for wireless local loop communication systems that allows multiple users to access the system while maintaining levels of internal interference and blocking sufficiently low so as not to affect radio communication. A person with certain knowledge in the subject of radio communications will recognize that the presented method can be adapted to other wireless networks thus increasing the quality of these systems as well. Figure 1, a wireless local loop communication system 10 is illustrated which can be used to carry out a radio communication with several user terminals. According to the illustrated, a radio access node ("RAN") 12, which can be placed in a tower 14 above the ground, is connected to a control chamber of RAN 16. The RAN 12 has the responsibility to transmit and receiving radio signals from any communication device that can be connected to the wireless local loop communication system 10, using one of several standardized communication protocols. In a wireless local loop communication system 10, a radio communication is carried out between the RAN 12 and a plurality of fixed access units 18 that can be connected to the home or business. The various fixed access units 18 may be connected to various communication devices, including, but not limited to, a telephone 10, a modem 22, a fax machine or another communication device capable of carrying out radio communication. Portable telephones 19 can also perform radio communication with the RAN 12 and the reference to fixed access units 18 should be considered as encompassing cellular telephones 19 and other types of communication devices adapted for radio communication. A typical RAN 12 comprises a plurality of fixed radio parts 24, 26, 28, 30, 32 and 34 arranged in a set and responsible for transmitting and receiving radio signals used by the various communication devices connected to the communication system 10 of wireless local loop (see figure A). The plurality of fixed parts of radius 24, 26, 28, 30, 32 and 34 are arranged in a geometric set in such a way as to encompass 360 ° of rotation in a horizontal plane. In accordance with that illustrated in Figure 1A, a set of six fixed radio parts 24, 26, 28, 30, 32 and 34 has been employed to create the RAN 12. A set of radio fixed parts can be made from 6, 12, 18 or more fixed radio parts and the presentation of six is only an exemplary title and does not intend to be any limitation. In accordance with what is illustrated in Figure IB, several RANs 12 are typically grouped together to create a wider coverage area. In order to allow users of the wireless local loop communication system 10 to communicate with the public, the RAN 16 control unit is connected to a public switched telephone network center 36. The public switched telephone network center 36 it is connected to the public switched telephone network (PSTN) 38 and allows users of the wireless local loop communication system 10 to communicate with any person connected to the public telephone networks. The RAN control unit 16 is usually located near the RAN 12 and has the responsibility to control the transmission and reception of radio signals between the RAN 12 and the plurality of fixed access units 18. The RAN control unit also has the responsibility to control the communication between a user in the wireless local loop communication system 10 and the public switched telephone network 38. In order to carry out a radio communication between the plurality of radio fixed parts 24, 26, 28, 30, 32 and 34 and the plurality of fixed access units 18, a standard digital communication protocol must be chosen. In preferred embodiments of the present invention, the communication method will operate using time division multiple access ("TDMA") as the standard communication protocol. TDMA is a well-known access technology that allows multiple users to occupy the same carrier frequency using time division. The standard TDMA format used in the United States of America is the IS-54 format and is known as the North American dual mode cellular format. In the United States of America the Federal Communications Commission (Federal Communications Commission) has assigned a radio frequency block from 1850 to 1990 MHz known as the PCS band. The upper frequency band is within a range of 1930 to 1990 MHz and the lower frequency band is within a range of 1850-1910 MHz for cellular communication. The European standard for digital wireless telephony using the TDMA format is commonly known as the Digital European Cordless Telecommunications ("DECT") standard (Digital European Wireless Telecommunications).

The communication method of the present invention advantageously employs the TDMA communication protocol. As illustrated in Figure 2, the TDMA protocol divides a plurality of carriers 401, 402 into a predefined repeating sequence of small time segments 42. Figure 3 illustrates a typical time segment 42. Each time slot 42 provides a communication device the ability to send or receive a certain number of data bits, 480 in formats usually employed at a carrier frequency 40 per time segment 42. Since a conversation including a transmission and a reception can employ only two segments of time 42, a single bearer frequency 40 can make several calls simultaneously. In accordance with what is illustrated in FIG. 3, the time segments 42 are usually cut into smaller time segments which may have small portions of data that can be used, for example, for a protection space 44, a field of synchronization 46, a signaling field 48, a data field 50, a CRC revision field 52 and a slip interference detection field 54. The exact function of each of these smaller time segments is not important to understand the system channel planning method of this invention. The invention employs several sequentially related carriers, which in the descriptions are represented by the sequential numbers 401-405. The carriers 401-405 can be selected from any portion of the frequency spectrum available for radio communication. Even when only five carriers 401-405 are discussed, one skilled in the art will understand that the number of carriers may vary. Preferred embodiments of the present invention comprise a communication method for wireless local loop communication systems. In the invention, a set 12 of several fixed radio-controlled parts 24, 26, 28, 30, 32 and 34 are provided that can carry out radio communication with the fixed access units 18. In accordance with the provisions set forth above. , a fixed access unit 18 can be either a mobile unit or a fixed access unit 18. Several carrier frequencies sequentially related are provided, for example, indicated as 401, 402, 403, 404 in Figures 4 and 5. to carry out radio communication between the various fixed parts of graduated radius 24, 26, 28, 30, 32 and 34 and the fixed access unit 18. The present method provides a series of frames 43 divided into a plurality of time segments 42 , in accordance with that illustrated in Figure 2. The frames 43 are all synchronized at each of the several sequentially related carrier frequencies 401-405. during the operation, the present method assigns each of the various sequentially related carrier frequencies 401-405 to a respective portion of the various fixed radio parts 24, 26, 28, 30, 32 and 34 in sequential order in each of the graduated time segments 43, as shown in FIG. 4. In addition during operation, the method scales each of the sequentially related carrier frequencies 401-405 during each successive time segment 43 by advancing the various sequentially related carrier frequencies 401-405 by a carrier frequency 401, eg, from 401 to 402, in each of the various fixed radio-controlled parts 24, 26, 28, 30, 32 and 34 as illustrated in FIG. Figure 4. Since the number of fixed radio parts 24, 26, 28, 30, 32 and 34 can exceed the number of sequentially related carrier frequencies 401-405, during operation, the last port frequency Available wiring, for example, 405 is replaced by the first carrier frequency ~ available, for example, 401, by sequencing the carrier frequencies 401-405. In the invention, the preferred method has preferably been the sequentially related carrier frequencies 401-405 in such a way that no fixed part of non-adjacent graduated radius 24, 26, 28, 30, 32 and 34 in set 12 is assigned to the same frequency of carrier when the number of fixed radio-controlled parts 24, 26, 28, 30, 32 and 34 exceeds the number of sequentially related carrier frequencies 401-405. For illustrative purposes only, let us consider, as illustrated in Figure 4, that a set 12 has 6 fixed radio parts 24, 26, 28, 30, 32 and 34 and the wireless local loop communication system 10 has only five available carrier frequencies 401-405 and six time segments TS1-TS6 per frame 43. As such, during the first time slot TS1, the present invention allocates a bearer frequency 401 to the first fixed part of radius 24, the carrier frequency 402 to the second fixed radio part 26, the carrier frequency 403 to the fixed third radio part 28, the carrier frequency 404 to the fixed fourth part of radio 30, the carrier frequency 405 to the fifth part fixed radio 32 and carrier frequency 403 to the fixed sixth part of radius 34. During operation, if the method continues to assign carrier frequencies 401-405 fully sequentially after the fifth fixed part of radius 32, in then the fixed sixth part of radius 34 would be assigned to the first carrier frequency 401. As such, the fixed sixth part of radius 34 and the first adjacent radius part 24 (see FIG. 1A) would be using the same carrier frequency 401. This would result in internal interference and would cause the wireless local loop communication system 10 to have a loss in radiocommunication quality. To avoid such loss in communication quality, the invention allocates the third carrier frequency 403 in the fixed sixth part of radius 34. The preferred method of communication for wireless local loop communication systems 10 may further comprise the step of dividing the series of frames 43 in a first set of time segments 43a and in a second set of time segments 43b. The preferred method may then comprise the steps of not allowing radio reception in the first set of fixed radio parts, (eg, fixed radio parts 24, 28 and 32) during the first set of time segments 43a; not permitting radio transmission in a second set of fixed radio parts (eg, fixed radio parts 26, 30, 34) during the first set of time segments 43a; not permitting radio transmission in the first set of fixed radio parts (eg radio fixed parts 26, 30 and 34) during the second set of time segments 43b; and not allowing radio reception in the other fixed radio parts (eg, fixed radio parts 26, 30 and 34) during the second set of time segments 43b.

The first set of fixed radio parts and the second set of fixed radio parts comprise fixed radio parts that are not adjacent. For example, none of the fixed radio parts 24, 28 and 32 of this first set are adjacent. This control of transmission and reception times ensures that no adjacent carrier frequency is transmitting or receiving at the same time, thus shining internal system interference. Another preferred embodiment of the present invention features a multi-channel planning method for a wireless local loop communication system 10. The preferred embodiment of the present invention comprises the steps of providing a series of frames 43, said frames 43 comprising a plurality of time segments 42; providing a plurality of fixed radio-controlled parts 24, 26, 28, 30, 32 and 34; provide a plurality of sequentially related carrier frequencies 401-405; assigning in sequential order each of the sequentially related carrier frequencies 401-405 to a respective part of the radio-controlled fixed parts 24, 26, 28, 30, 32 and 34 in each of the time segments 42; advancing each of the several sequentially related carrier frequencies 401-405 each successive time segment 42 by a predetermined number of carrier frequencies, the last carrier frequency 405 of the plurality of sequentially related carrier frequencies 401-405 is followed by the first carrier frequency 401; and assigning the various sequentially related carrier frequencies such that no adjacent radio part 24, 26, 28, 30, 32 and 34 in the set 12 receives the same carrier frequency. The preferred method may further comprise the step of dividing each of the frames 43 into a first set of time segments 43a and into a second set of time segments 43b. To further reduce the internal interference caused by the operation of the wireless local loop communication system 10, the preferred method may not allow radio reception in a first set of radio fixed parts and not allow radio transmission in a second set of fixed radio parts during the first set of time segments 43a. In addition, the preferred method may not allow radio transmission in the first set of radio fixed parts and not allow radio reception in the second set of radio fixed parts during the second set of time segments 43b. Another preferred embodiment of the present invention features a wireless local loop communication system 10 that can carry out wireless communication while maintaining internal interference levels within acceptable ranges. The system comprises a plurality of fixed radio-controlled parts 24, 26, 28, 30, 32 and 34 placed in a set 12 which are used to carry out radio communication with several fixed access terminals 18. The system employs several frequencies sequentially related carrier carriers 401-405 divided into a series of frames 43 comprising a plurality of time segments 42. A control unit is connected to the various fixed radio-controlled parts 24, 26, 28, 30, 32 and 34 for assigning each of the sequential carrier frequencies or 401-405 to a respective part of the various fixed radio-controlled parts 24, 26, 28, 30, 32 and 34 in sequential order in each of the time segments 42. During operation, the control unit 16 scales each of the sequentially related carrier frequencies 401-405 with each successive segment of time 42 by advancing the various frequencies of sequential carriers. connected by a predetermined number of carrier frequencies in each of the radio-controlled fixed parts 24, 26, 28, 30, 32 and 34. When sequencing the frequencies, the last carrier frequency 401-405 of the series of sequentially related carrier frequencies 401-405 is replaced by the first carrier frequency (eg 401) when the number of radio-set fixed parts 24, 26, 28, 30, 32 and 34 exceeds the number of sequentially related carrier frequencies 401-405. In preferred embodiments of the present invention, the predetermined number of carrier frequencies through which the system advances is a carrier frequency, such as, for example, 401 to 402, 402 to 403, etc. In preferred embodiments of the wireless local loop communication system 10, the control unit 16 allocates the sequentially related carrier frequencies 401-405. such that no fixed part of adjacent graduated radius 24, 26, 28, 30, 32 or 34 receives the same carrier frequency when the number of fixed radio-controlled parts 24, 26, 28, 30, 32 and 34 exceed the number of sequentially related carrier frequencies 401-405. As reference to Figures IA and 4, a preferred embodiment of an assembly 12 having 6 fixed parts of radius 24, 26, 28, 30, 32 and 34 could receive 5 sequential carrier frequencies 401-405 for use during a frame 43 having 6 time segments 42. according to the described the number of radio parts exceeds the number of available carrier frequencies. When the carrier frequencies are assigned to each of the fixed radio parts 24, 26, 28, 30, 32 and 34, they are assigned sequentially. As such, during operation, the fixed part of radius 24, would be assigned to the first carrier frequency 401, the second fixed part of radius 26 would be assigned to the second carrier frequency 402, the third fixed part of radius 28 would be assigned at the third carrier frequency 403, the fourth fixed part of radius 30 would be assigned to the fourth carrier frequency 404, and the fifth fixed part of radius 32 would be assigned to the fifth carrier frequency 405. Due to the fact that the first part fixed radio 24 was assigned to the first carrier frequency 401, the fixed sixth radio part can not be assigned to the first carrier frequency 401. using the same carrier frequency in adjacent fixed radio parts 24, 34 during a segment of time 42, there would be an internal interference with the radio communication in leather. Accordingly, as each of the fixed parts of radius 24, 26, 28, 30, 32 and 34 advances in carrier frequency assignment during each successive time segment 42, no fixed part of adjacent radius 24, 34 will use the same carrier frequency. Figure 5 illustrates the channel allocation method that could be employed in a RAN 12 having 12 fixed radio parts.

In another preferred embodiment of the present invention, the wireless local loop communication system 10 divides the frames 43 into a first set of time segments 43 there a second set of time segments 43b. In order to further reduce the internal interference, the control unit 16 does not allow radio reception in the fixed radio parts with odd numeration or transmission in the fixed radio parts with even numbering during the first set of segments of time 43a. In the same way in the second set of time segments 43b, the control unit 16 does not allow the radio transmission in the fixed parts of graduated radio with odd numbering nor does it allow the reception of radio in the fixed parts of radius graduated with numbering pair. Although several preferred embodiments of this invention were presented, one skilled in the art will recognize that the methods presented can be employed in numerous types of communication systems. It will be understood that a broad spectrum of changes and modifications to the embodiments described above will be apparent to those skilled in the art and contemplated within the invention. Accordingly, the foregoing detailed description is considered as illustrative but not limiting and is understood to be the following claims, including all equivalents that define the spirit and scope of the present invention.

Claims (19)

1. CLAIMS A communication method for wireless local loop communication systems, comprising the steps of: providing a set of several fixed parts of radio gradients; provide several sequentially related carrier frequencies; provide a series of frames divided into several time segments with the various sequentially related carrier frequencies; assigning each of the various carrier frequencies sequentially related to a respective part of the various fixed radio parts set in sequential order in each of the time segments graduated; e) graduating each of the sequentially related carrier frequencies during each successive time segment by advancing the various carrier frequencies sequentially related by a carrier frequency in each part of the various fixed radio-frequency parts, the last carrier frequency of the series of sequentially related carrier frequencies is followed by the first carrier frequency in the graduation in each part of the various fixed parts of graduated radius.
2. The method according to claim 1, further comprising the step of allocating the sequentially related carrier frequencies such that no fixed part of non-adjacent graded radius in the set receives the same carrier frequency when the number of fixed parts of Graduated radius exceeds the number of sequentially related carrier frequencies.
3. The method according to claim 1, further comprising the step of dividing the series into frames into a first set of time segments and into a second set of time segments.
4. The method according to claim 3, further comprising the step of not allowing radio reception in a first set of radio-set fixed parts during the first set of time segments.
5. The method according to claim 3, further comprising the step of not allowing a radio transmission in a second set of radio-set fixed parts during the first set of time segments.
6. The method according to claim 3, further comprising the step of not allowing radio transmission in a first set of radio-set fixed parts during the second set of time segments.
7. The method according to claim 3, further comprising the step of not allowing the reception of radio in a second set of radio-set fixed parts during the second set of time segments.
8. A method of planning multiple channels for a wireless local loop communication system, comprising the steps of: providing a series of frames, said frames comprising a plurality of time segments; providing a plurality of fixed parts of radius graduated; provide a plurality of sequentially related carrier frequencies; assigning a sequential order to each one of the carrier frequencies sequentially related to a respective part of the radio-fixed fixed parts in each of the time segments; advancing each of the various sequentially related carrier frequencies in each successive time segment by a predetermined number of carrier frequencies, the last carrier frequency of the plurality of sequentially related carrier frequencies is followed by the first carrier frequency in each successive time segment; assigning the plurality of sequentially related carrier frequencies such that no fixed part of adjacent radio in the set receives the same carrier frequency.
9. The method according to claim 8, further comprising the step of dividing each of the frames into a first set of time segments and a second set of time segments.
10. The method according to claim 9, which further comprises the step of not allowing radio reception in a first set of radio-set fixed parts during the first set of time segments.
11. The method according to claim 9, further comprising the step of not allowing radio transmission in a second set of radio-set fixed parts during the first set of time segments.
12. The method according to claim 9, further comprising the step of not allowing radio transmission in a first set of radio-set fixed parts during the second set of time segments.
13. The method according to claim 9, further comprising the step of not allowing radio reception in a first set of radio-set fixed parts during the second set of time segments.
14. A wireless local loop communication system, comprising: a plurality of radio-controlled fixed parts; a plurality of sequentially related carrier frequencies, said sequentially related carrier frequencies are divided into a series of frames having a plurality of time slots; a control unit connected to the plurality of radio-set fixed parts for assigning each one the carrier frequencies sequentially related to a respective part of the various fixed radio parts set in sequential order in each of the time segments; wherein the control unit scales each of the sequentially related carrier frequencies during each successive time segment by advancing the plurality of sequentially related carrier frequencies a predetermined number of carrier frequencies in each of the fixed radio parts In the case of graduated, the last carrier frequency of the series of sequentially related carrier frequencies is followed by the first carrier frequency.
15. The wireless local loop communication system according to claim 14, wherein the sequentially related carrier frequencies are allocated in such a way that no fixed part of adjacent graduated radio receives the same carrier frequency when the number of fixed parts of Graduated radius exceeds the number of sequentially related carrier frequencies.
16. 16. The wireless local loop communication system according to claim 14, wherein said frames are divided into a first set of time segments and a second set of time segments.
17. 17. The wireless local loop communication system according to claim 16, wherein the control unit does not allow radio reception in a first set of radio-set fixed parts during the first set of time slots.
18. 18. The wireless local loop communication system according to claim 16, wherein the control unit does not allow radio transmission in a second set of radio-set fixed parts during the first set of time slots.
19. 19. The wireless local loop communication system according to claim 16, wherein the control unit does not allow radio transmission in a first set of radio-set fixed parts during the second set of time slots. The wireless local loop communication system according to claim 16, wherein the control unit does not allow radio reception in a second set of radio-set fixed parts during the second set of time slots.