HK1017560B

HK1017560B - Method for radio resource control

Info

Publication number: HK1017560B
Application number: HK99102513.6A
Authority: HK
Inventors: K‧赖克基年; K‧阿姆阿瓦拉; M‧J‧林内; M‧林内
Original assignee: Nokia Corporation
Priority date: 1996-10-25
Filing date: 1999-06-09
Publication date: 2004-02-13

Description

Radio resource control method

The present invention relates generally to sharing radio resources between various users in a cellular radio system. In particular, the invention relates to sharing radio resources in systems where the data transmission of users requires rapid changes in quality and quantity.

At the time of filing this application, the most common form of mobile personal telecommunications is a second generation digital cellular radio network; these networks include the european System gsm (global System for mobile telecommunications) and its branch DCS1800 (digital communication System at 1800 MHz), the north american (USA) System IS-136 (interim standard 136), IS-95 (interim standard 95) and the japanese System PDC (personal digital cellular). These systems mainly transmit voice, user fax and short text messages, but also transmit digital data at a limited speed, such as files transmitted between computers. Several third generation systems are being designed with the goal of worldwide coverage, large selection of data transmission services, and flexible capacity sharing, such that a given user transmits and/or receives large amounts of data, even at high rates, when needed.

The european telecommunication standards institute ETSI has proposed a third generation mobile telecommunication system known as UMTS (universal mobile telecommunications system) targeted to a wide operating environment including residential, office, urban and rural environments as well as fixed and mobile stations. The choice of services is large and the types of mobile stations include, in addition to currently known mobile telephones, multimedia terminals and multi-purpose terminals which, for example, communicate telecommunications between the UMTS system and various local systems.

Fig. 1 shows an exemplary cell 11 of a UMTS system equipped with a fixed base station subsystem 12(BSS), within the range of which there are several different mobile stations 13 that exist or move with the user. The base station subsystem may include one or more base stations and also include a base station controller that controls their operation. Between the base station subsystem and the mobile station there is a radio connection to which a given radio frequency range is reserved and whose operation is adjusted by means of the system specifications. The time available for a radio connection together with the frequency range defines the so-called actual radio resources. One of the biggest challenges of the base station subsystem is to control the utilization of these actual radio resources so that all terminals located within the coverage area of a cell can receive data transmission services of the requested quality at any time, while adjacent cells interfere as little as possible with each other.

In prior art systems, there are several known methods for sharing radio resources. In Time Division Multiple Access (TDMA), each used transmit and receive frequency band is divided into time slots, and the base station subsystem allocates one or several of the periodically repeating time slots for use by a given terminal. In Frequency Division Multiple Access (FDMA), the frequency range used is divided into very narrow frequency bands, and the base station subsystem allocates one or several of these frequency bands to each terminal. Many current systems employ a combination of these, with each narrow band being further divided into time slots. In Code Division Multiple Access (CDMA), a spreading code is obtained at each connection between a mobile station and a base station subsystem, thereby randomly spreading the transmitted information over a substantial frequency range. The codes used within the cell coverage are mutually orthogonal or nearly orthogonal, in which case the receiver identifying the code can distinguish the desired signal and attenuate other simultaneous signals. In Orthogonal Frequency Division Multiplexing (OFDM), which is mainly suitable for broadcast type services, data is transmitted from a transmission central station over a wide frequency band divided into equidistant sub-frequencies, and the simultaneous phase shifting of these sub-frequencies produces a two-dimensional bit stream in a time-frequency space.

For packet-switched radio network technology, there are also known various packet-based connection protocols in which the connection between the mobile station and the base station subsystem is not continuous, but continues with suspended packets of varying duration between changes. Compared to a continuously connected system, i.e. to a so-called circuit-switched network. Has the advantages that: when there is a temporary suspension in the connection, it is not necessary to occupy the radio resources required by the designated connection. The disadvantages are that: there is generally a long data transmission delay since the new packet transmission requires the exchange of some control or signaling messages between the mobile station and the base station after each pause. Different packet routing between the sender and the receiver can also cause delays.

The third generation cellular radio networks are characterized by: for example in the case of fig. 1, with some terminals 13 it is sufficient to have a rather low capacity radio connection with the base station, while some terminals 13 at least temporarily need a much larger share of the common radio resources than the rest of the terminals. For example, the low capacity connection may be a voice connection, while the high capacity connection may be, for example, an image file in a data network connection loaded to the mobile station via the base station subsystem or a video image connection during a video telephone call. In the prior art, there is no method for a base station subsystem to divide the available radio resources among various users in a flexible and dynamic manner. Some related prior art methods are discussed below.

US patent No. 5533044 discloses a frame structure in which each slot size is the same. Different amounts of data can be transmitted in each time slot by selecting a modulation method according to requirements.

An article "TDMA Based Adaptive Modulation with dynamic Channel Assignment (AMDCA) for Large Capacity voice transmission in Microcellular Systems (TDMA-Based Adaptive Modulation with dynamic Channel allocation for Large Capacity voice transmission in Microcellular Systems)" by t.ikeda et al, in Electronics Letters, volume 32, vol 13, page 13, 1175-1176, 1996, month 6, 20, discloses another frame structure with a plurality of equally sized time slots. Each connection has the same data rate but different modulation methods are used to compensate for varying connection quality. A faulty connection gets more time slots than a connection with a better quality so that the faulty connection can use a stronger modulation scheme.

Patent document No. GB 2174571 discloses a frame structure that can accommodate a varying number of time slots, each connection having the same data rate, but using different modulation schemes to provide robustness against noise and interference. The length of each slot in a frame depends on the modulation method used in the connection to which the slot is assigned.

Patent document No. EP633671 describes a method of multiplexing acknowledgement messages used in a packet-switched radio system. Instead of letting each mobile station freely send its acknowledgement message in a Random Access (RA) gap, the system divides the RA gap into sub-gaps by truncating the RA gap to a shorter time interval or allocating orthogonal codes for the duration of the RA gap. Only one mobile station or a small group of mobile stations is allowed in each sub-slot to reduce the risk of acknowledgement messages colliding with each other.

The object of the present invention is to introduce a flexible and dynamic radio resource partitioning method in a base station subsystem of a cellular radio network.

The object of the invention is achieved by dividing the radio packet resources in the base station subsystem or similar responsible for radio resource division into frames, wherein the base station subsystem can allocate the frames for use by different connections according to the traffic demands at the moment, the size of the various modules (models), the size of the parameterisation parts. These frames are repeated periodically so that the repeated sequence contains a single frame or a set of consecutive frames.

The method of the invention is characterized in that: the actual radio resources are divided in sequence into successive frames containing gaps with variable data transmission capacity, such that each gap represents a given portion of the actual resources contained in the frame, and each gap can be allocated independently for use by a given radio connection.

In the method of the invention, the so-called real layer of the transmission channel between the first radio station and the second radio station is divided into frames. The exemplary designations "base station" and "mobile station" are used in this patent application to distinguish wireless telephones from one another. Each frame may also be divided into smaller cells, the cell size being defined by two coordinates or dimensions, which makes the subdivision of the frame a conceptual two-dimensional structure. The first dimension is time, which means that a frame has a given duration in time, which time may also be divided into consecutive time slots. In a preferred embodiment of the invention, each frame contains the same number of slots, but the use of slots may vary from frame to frame. The second dimension may be time, frequency or code. If the second dimension is also time, each slot of the frame is further divided into smaller sub-slots. If the third dimension is frequency, a narrower band than the total allocated band covered by this frame can be extracted in each time slot comprised by the frame. If the third dimension is a code, a given number of mutually orthogonal or near-orthogonal codes may be obtained during each time slot.

The smallest resource unit allocated from one frame is a gap, the size of which is defined by the slot length in the first dimension and by the partition unit determined according to the properties of the second dimension in the second dimension. For example, in a time-frequency frame, the size of the gap in the second dimension is the frequency bandwidth employed in each case. A gap is always allocated as a whole for a connection. It is important to note that the slots are conceptually different from the slots in this patent application. One slot is typically a division unit of a frame in the time dimension and one slot is the actual radio resource unit that can be allocated to a single connection.

Some predetermined number of consecutive frames form a so-called superframe. Since the various numbers are generally most naturally powers of 2 in digital systems, a superframe advantageously contains 1, 2, 4, 8, 16, 32, or 64 frames. The flexibility and dynamic adaptability of the method according to the invention are: the slots contained by a given frame need not be equal in size, the slot structures of the frames contained in the superframe need not be similar, and an equal number of slots need not be allocated from a frame or superframe to each connection. The gap structure and the gaps reserved for various connections may vary from superframe to superframe. On the other hand, if the data transmission requirements do not change, then the first frame in a given superframe has a similar gap structure as the first frame of the previous superframe, the second frame is similar to the second frame of the previous superframe, and so on. The word superframe is naturally only an example name that may represent one or more successive frame concepts.

In uplink data transmission, i.e. in transmission from the mobile station to the base station subsystem, the mobile station needs some arrangement with which the mobile station can reserve the data transmission capacity to use. In a preferred embodiment of the invention, each uplink superframe contains a random access gap during which the mobile station is free to send packet-shaped capacity requests. Accordingly, the downlink superframe contains an allocation grant gap in which the base station subsystem informs of the allocation of grants. Admission is based on successful reception of capacity requests by the base station subsystem and according to priority rule settings of different types of connections and prevailing traffic load. The base station subsystem advantageously maintains a reservation table of superframe sizes, where it manages the allocation so that the available radio resources are utilized in an optimal manner.

In downlink data transmission, the base station subsystem similarly allocates data transmission capacity according to the priority rule settings of the different types of connections and the main traffic load. It preferably notifies the allocation to the downlink in the same paging message that it uses to notify the mobile station of the incoming downlink transmission request. Once the mobile station has confirmed the correct receipt of the paging message, the downlink transmission may begin using the allocated transmission capacity.

The invention will be described in more detail below with reference to the accompanying drawings and preferred embodiments provided as examples, in which:

figure 1 shows a known cell in a cellular system;

FIG. 2a shows some structural components of a frame according to the present invention;

FIG. 2b shows a variation of FIG. 2 a;

fig. 3 illustrates a superframe according to a preferred embodiment of the present invention;

fig. 4a illustrates uplink real-time data transmission according to a preferred embodiment of the present invention;

FIG. 4b shows the temporal shape of the message of FIG. 4 a;

fig. 5a shows downlink real-time data transmission according to a preferred embodiment of the present invention;

FIG. 5b shows the timing shape of the message of FIG. 5 a;

fig. 6a illustrates uplink non-real time data transmission according to a preferred embodiment of the present invention;

FIG. 6b shows the temporal shape of the message of FIG. 6 a;

fig. 7a illustrates downlink non-real time data transmission according to a preferred embodiment of the present invention;

FIG. 7b shows the timing shape of the message of FIG. 7 a;

FIG. 8 illustrates message timing shapes in asymmetric transmission resource sharing in accordance with a preferred embodiment of the present invention;

fig. 9 illustrates full TDD operation according to the present invention;

fig. 10 illustrates a method for adjusting transmission power according to the present invention;

FIG. 11 shows an advantageous algorithm for gap allocation;

figure 12a shows a block diagram of a base station subsystem according to the invention; and

fig. 12b shows a block diagram of a mobile station according to the invention.

Reference has been made above to fig. 1 in the description of the prior art, and therefore in the following description of the invention and its preferred embodiments, we will refer primarily to fig. 2a-12 b. In the drawings, like parts are numbered identically.

Fig. 2a shows a two-dimensional frame 14 according to a preferred embodiment of the invention, in the above description the first dimension of the hold frame is time, while the second dimension may be time, frequency or code. In the case of fig. 2a, the second dimension of the frame 14 is frequency or time. The size of the frame in both dimensions must be chosen such that it is compatible with other specification settings of the system. In this example, the length of a frame in the time direction is about 4.615 milliseconds, and is divided into eight slots in the time direction, with one slot 15 being about 0.577ms in length. The frame width in the frequency direction is about 2 MHz.

The smallest uniform structural unit of a frame, i.e. a slot, is the various subdivisions of the time slot 15. In the lower left part of fig. 2a, time-frequency division is used, so that the sequential length of each gap is the same as the slot length, but its width in the frequency direction may be 200KHz, 1MHz or 2 MHz. Reference numeral 16 denotes a large 0.577ms x 2MHz gap, reference numeral 17 denotes a medium size 0.577ms x 1MHz gap, and reference numeral 18 denotes a small 0.577 x 200MHz gap. In the lower right part of the figure, time-time division is employed so that each gap occupies the entire 2MHz bandwidth of the system, while its sequential duration may be 1/1, 1/2 or 1/10 of the time slot length. Reference numeral 16 again denotes a large 0.577ms x 2MHz gap, reference numeral 17 denotes a medium size 0.2885ms x 2MHz gap, and reference numeral 18 denotes a small 0.0577ms x 2MHz gap. In those partitions where five small slots share a slot with row C of one example of a mid-size slot partition, it is naturally possible to provide one mirroring option (e.g., one slot starting with a mid-size slot and ending with five small slots).

According to another proposal, the number of different gap size types is 4, and their relative sizes are: the gaps of the largest size type correspond to 2 gaps of the second largest size type, 4 gaps of the third largest size type and 8 gaps of the smallest size type. Other arrangements of relative gap sizes are possible.

A carrier scheme in which one frame can contain several units having different frequency bandwidths is called a parallel multi-carrier structure. The base station subsystem may change the frame structure such that it replaces 1 large slot with 2 medium sized slots, 10 small or 1 medium size plus 5 small slots, or vice versa, or such that it replaces 1 medium sized slot with 5 small slots or vice versa. This property is called the modularity of the frame: a given gap or group of gaps forms a module (like the group of 5 small gaps 18 on row C of the split example), which can be replaced by a different module (like the single intermediate-sized gap 17 on row B of the split example) in the corresponding time slot contained in some following frame, so that the remaining content of the frame does not change and the available frequency band can always be optimally utilized. The invention does not limit the number of time slots contained in a frame nor the allowed carrier bandwidth, but to maintain modularity the gaps are integer multiples of each other with respect to their dimension, which is particularly advantageous. For example, 3 250KHz wide gaps in the time-frequency division might be modularly replaced by 450KHz wide gaps, while only 1 450KHz gap is put into the space left by the three narrower gaps, and the 300KHz bandwidth would be left unused.

The invention does not require that the frames occupy a continuous frequency range (2MHz in fig. 2 a). It is possible to define a frame to cover 2 or more independent frequency bands. Even a single gap may cover 2 or more independent frequency bands, which naturally requires that the respective transceiver has multiple operational capabilities, i.e. the ability to receive and correctly combine received information simultaneously in reception on at least two different reception frequency bands, and the ability to divide the information in transmission into at least two independent transmitter branches and transmit it simultaneously on at least two different transmission frequency bands.

Fig. 2b shows CDMA according to fig. 2a with an alternative slot division. During each time slot 15 there may be different numbers of allowed spreading codes with different spreading ratios. The spreading ratio is a characteristic property of the spreading code and from the point of view of resource sharing it defines that a plurality of actual radio resources must be allocated to a single connection. The larger the spreading ratio of the spreading code used in a connection, the lower the bit rate in that connection and correspondingly the larger the number of simultaneous connections possible during a given time period using a given bandwidth. In the example of fig. 2b, three types of spreading codes may be used. The code 1 type spreading code has a small spreading ratio R so that the information transmitted together with the code 1 type spreading code fills the capacity of the whole time slot (row a). The spreading ratio of the code 2 type spreading code is 2R (i.e. 2 times code 1), so that two connections using orthogonal or near-orthogonal code 2 type spreading codes can exist simultaneously in a single time slot (row B:). The spreading codes of the code 3 type have a spreading ratio of 10R (i.e. 10 times code 1), so different orthogonal or near-orthogonal spreading code combinations may exist simultaneously, on row C: this slot accommodates 5 connections with code 3 type spreading codes and 1 connection with code 2 type spreading codes, on line D: in 10 simultaneous connections with code 3 type spreading codes. A simple comparison between fig. 2a and 2b shows: the time-code division may be translated to define gaps in a manner similar to that used for time-frequency or time-time division.

In addition to the gap size, the gap capacity, i.e., the amount of data that can be transmitted in a gap, depends on the modulation and error protection method used in the data coding, as well as the modulation and error protection method used in the remaining signal structure coding in the gap. In the time-frequency arrangement according to fig. 2a, in which the allowed bandwidths are 200KHz, 1MHz and 2MHz, it was found to be advantageous to use binary offset (binary-offset) QAM (B-O-QAM), binary offset quadrature amplitude modulation) over the 2 narrower bandwidths (200KHz and 1MHz) and quaternary offset (quaternary offset) QAM (Q-O-QAM, quaternary offset quadrature amplitude modulation) over the widest bandwidth (2 MHz). Other modulation methods are possible and are well known to those skilled in the art.

Fig. 3 illustrates a superframe according to a preferred embodiment of the present invention. It has been pointed out that: the invention does not limit the number of consecutive frames contained in a superframe, but a useful number is a power of 2. A superframe may consist of only 1 frame in the shortest. In the case of fig. 2, the superframe 19 contains four orthogonally consecutive frames 14. Here, the frames have consecutive numbers such that the number of the first frame is described by the letter N representing a non-negative integer, the next frame is N +1, the next frame is N +2 and the number of the last frame in the super-frame is N + 3. The slots of the frame are also numbered in consecutive non-negative integers such that the first slot in each frame is number 0 and the last slot is number 7. This figure also shows by way of example the partitioning of slots into payload slots and control data slots. Slots containing appropriate data, i.e. payload information, that can be transmitted are marked with the letter I (information), while slots containing control data, i.e. signalling data, are marked with the letter C (control).

The control data gaps form one or several logical control channels, which may be used, for example, to send messages controlling the start, maintenance and end of a connection, to define the requirements for changing the base station and to exchange commands and measurements between the base station subsystem and the mobile station regarding transmission power and power saving modes of the mobile station. It is advantageous to place the control gaps in some relatively tight part of each frame containing the control gaps, since in this way the rest of the frame can be very flexibly located in different module gap combinations. If the control gaps are spread out over the entire frame structure, only a limited selection of allocable gaps will apply between them.

According to a preferred embodiment of the invention, the base station subsystem (or the corresponding device responsible for radio resource partitioning) maintains a parameterized reservation table indicating the size status of each gap occupancy and other possible parameters related to this gap. The reservation table is maintained for the duration of time during which one superframe is active at a time, between superframes in the slot structure of frame 14 and/or in the allocation of slots for a given connection between superframes. To ensure optimal operation, the base station subsystem must have a reservation table routine that maintains the reservation table according to a given evaluation criterion. Among such repetition criteria to be taken into account by the reservation table routine before granting access to the new connection are, for example, traffic load, the type of information contained in the new connection (e.g., voice, video, data), the priority defined on the basis of the new connection (e.g., normal call, emergency call), the general power level of the traffic load, and the type of data transmission connection (e.g., real-time, non-real-time). Furthermore, it is possible to define more complex criteria, such as the interference sensitivity of a given gap and the transmission power required by that gap.

If a base station also takes into account the reservation tables of surrounding base stations, it can allocate gaps in its own reservation table according to the power level and switching type of the connection. The former means that: mobile stations using high power levels and low power levels have their own allocated gaps in the best position according to the total interference of the system, which gaps are located in the reservation tables of the neighboring base stations. The latter means that: the circuit switched and packet switched connections have their own gaps in the reservation tables of the neighbouring base stations in the best position according to the total interference of the system. Optimality is defined such that all users are exposed to the noise signals of other users as little as possible. If the gaps are allocated, for example, according to power levels, the first base station grants low power users (those users located close to the first base station) access to the gaps during which there is a connection for one high power user (one user remote from the second base station) in the second base station.

Previously known gap allocation methods are typically sequential (e.g., in 8 available gaps, first gap number 0, then gap 1, etc.; or first gap number 0, then in the order of gaps 2, 4, 6, then gaps 1, 3, 5, and 7) or random, and in connection with the present invention have been found: it is advantageous to use a gap allocation method that takes into account different evaluation parameters that can be used to describe each gap. The base station subsystem may measure the noise level in each gap and arrange the free and allocable gaps according to their quality, i.e. noise level. If the new gap request indicates a very tight real-time requirement that the desired new connection should have limited retransmission possibilities, the base station subsystem will give it a very high quality gap with a low noise level. Non-real-time connections with good retransmission tolerances can get lower quality gaps to keep the best gap arbitrary for possible future real-time connection requests. The size of one gap is important: if there are small and large gaps free and available in a frame and 1 new gap request indicates only a small resource requirement, it is advisable to allocate an existing small gap to it, even if it can get a better quality gap by replacing the 1 larger gap with a set of smaller gaps in a modular way and the allocation of one of those gaps.

The representation of the gap allocation method in the base station subsystem may be allocation or logical algorithm (chain of conclusions) former meaning: the base station weights the considered correlation factors (noise level, real-time service requirements, need to partition large gaps, estimated power level, etc.) with different calculations and calculates a structure representing a certain gap. The latter means that: the base station subsystem maintains a set of candidate gaps and evaluates them (one at a time) to find which is best suited for the newly requested connection. Fig. 11 shows an exemplary logical algorithm that the base station subsystem may use to determine which gap it will allocate to a given new connection. Operation begins with a gap request 100, which request 100 may be from the network side (downlink gap request) or from the mobile station side (uplink gap request). In block 101 the base station subsystem detects which frame store (uplink or downlink) it should select. The actual selection of memory (reservation table) is made as a background process in blocks 102, 103 or 104 and the algorithm proceeds to block 106. Here, a frame selection process 107, 108, 109 like frame memory selection is started. In this figure, we propose: each superframe consists of 2 frames.

In block 110, the base station subsystem begins the evaluation process with the time slot having the lowest fragmentation value, i.e., containing the largest gap. In block 111 it rejects all slots where the new connection will result in a multi-carrier allocation. In block 112 it checks if there are any other factors that prevent the use of the slot (too small a gap size, preset transmission power limits, unacceptably high noise levels, etc.) and if there are no such factors it updates the set of candidate slots. Block 114 causes the repetition of steps 110, 111, 112, 113 and possibly 105 until all slots have been scanned. In block 115, the base station finds the best candidate slot by applying certain radio resource management rules and selection criteria. For example, there may be two best candidates with equally low interference, and the base station subsystem must check: whether the power requirements estimated for the new connection are consistent with certain preset power and noise limits in each gap, and whether the selection of any best candidate would imply a computational cost in the form of partitioning large gaps into smaller gaps.

After the selection in block 115, the base station subsystem additionally checks in block 116: whether the calculated quality estimate 117 represents a sufficiently high transmission quality. Normally, the procedure continues to block 118, but it may occur that even the best candidate gap will not provide sufficient quality. In this case the base station subsystem moves to block 119 which starts a possible change of operation mode to improve the transmission quality in block 119 and ends the procedure in the gap assignment decision 120.

In the method according to the invention, the sharing of radio resources takes place in a similar manner with respect to real-time and non-real-time traffic: the base station subsystem (or corresponding device responsible for radio resource partitioning) allocates a gap for each service according to the service needs. Similar control messages and mechanisms adjust the radio resource distribution in both cases, only the specific content of the control messages and some of the allocation and reallocation principles differ slightly depending on the type of traffic in question. The transmission of data over the radio path during an established connection differs slightly depending on whether the traffic in question is real-time or non-real-time. Applications requiring real-time or near real-time services are, for example, voice transmission in packets and video connections required by videophones. In the simulation of the method according to the invention it is assumed that: when the longest allowed data transmission delay is 30ms, a Bit Error Rate (BER) of 10 is obtained in the speech transmission between the base station subsystem and the mobile station^-3. In a video connection requested by a videophone, the corresponding value is 10^-6And 100ms, where longer delays are caused due to time interleaving of the transmitted data. These services employ a forward error correction (FFC) type error correction and radio resource backup protocol, which will be explained in more detail below. Non real-time traffic is for example file transfers in ordinary internet connections, which employ packet type data transfer and ARQ type error correction protocols (automatic repeat request).

In the following we will observe real-time uplink data transmission in the normal case in connection with fig. 4a and 4b, the arrows of fig. 4a representing data transmission between the Base Station (BS) and the Mobile Station (MS) in chronological order, so that the time in the figure is from top to bottom. Some superframes transmitted by the base station contain so-called Y-slots, in which the base station informs when a PRA (packet random access) slot is next found in the uplink direction, i.e. the point in the uplink superframe where the mobile station can transmit a capacity request. Arrow 20 represents data transmitted in the Y-slot of a given downlink superframe regarding the location of the next PRA slot. If the PRA slots have a constant position in every uplink frame or superframe, the base stations do not have to inform their position in the Y slots, which increases the system's flexibility to reserve the base station subsystem the possibility to place the PRA slots in the most appropriate way and to change their position between superframes.

According to arrow 21, a PRA message is requested in one of the successive PRA slots sent by the mobile station, in which message it identifies itself and informs what type of connection (real-time, coding, slot type, etc). Since there is no protocol between different mobile stations, it may happen that several mobile stations send one PRA message at the same time. In this case, at most one is received. However, in fig. 4a it is assumed that a PRA message is received according to arrow 21, in which case the base station informs according to arrow 22 in the PRA (packet access grant) gap of the next downlink frame: the specified uplink gap is granted to the mobile station while it passes through the location of the granted gap in the uplink superframe. In prior art packet access protocols, a requesting station typically obtains as its radio resource the time slot or other corresponding resource point in which it has sent a successful capacity request. According to the present invention, the gap allocated to the connection can be located anywhere within the next uplink superframe.

When the mobile station has received the information of the granted radio resources it starts transmitting data according to arrow 23. During this connection, it may happen that the mobile station wants to increase the amount of radio resources it has acquired. In that case it reserves further gaps by sending a capacity request of what type and with what kind indicating how large the new gap should be. It may also occur that the data transmission needs of the mobile station decrease during the connection and that it wants to reduce the used radio resources. At which point it ends transmission in the gap designated according to arrow 25, in which case the base station can allocate the released gap for use by other connections. Arrow 26 represents a message used by the mobile station to end the transmission.

Fig. 4b is used to illustrate some of the above messages in relation to the timing of frames and superframes. Here, we assume that: there are 2 frames 14 in each superframe 19, we also assume: the transmission in the Downlink (DL) direction takes place simultaneously with the transmission in the corresponding Uplink (UL) direction, both of which inform, for example, Frequency Division Duplex (FDD) that they are placed on different frequency bands so that they are separated from each other. We also assume that: in the middle of each frame 14 there is a control gap range which is shown in figure 4b as a silhouette. Placing the control gap range in both the downlink and uplink directions is advantageous because it will prevent the loss of important control information due to simultaneous traffic transmission. Other methods can also be used to prevent any traffic transmission opportunity loss due to control information readout. The frames in fig. 4b are from left to right in chronological order.

The mobile station listens to the downlink transmission DL and finds the slot address of the next available PRA slot in a message sent by the base station in the Y slot. These available PRA slots are located in the second frame of the leftmost superframe of fig. 4 b. The dashed line represents the logical connection between the slots, in other words it represents that the message sent in a certain Y slot in the figure controls the use of the PRA slot in the next complete UL frame. The mobile station transmits a PRA message to the base station using the PRA gap. Assuming this attempt is successful, the base station transmits a PAG message in the PAG gap of the next full DL frame. This PAG message tells the mobile station to use certain gap(s) RT from the next full UL frame for the desired transmission for real-time traffic. The dashed line from the PAG gap to the next full UL frame indicates that the granted UL gap can be anywhere in the frame. Transmission continues in the same gap until either the data source is exhausted or the base station sends a separate RT uplink channel update command (not shown in figure 4 b).

Downlink real-time data transmission is performed according to fig. 5a and 5 b. No separate gap capacity request is required because the base station subsystem itself maintains a gap reserve table and can therefore direct downlink data transmissions to the appropriate gap. A message telling the mobile station the selected slot position may be sent to the mobile station over a Packet Paging (PP) channel, at least one PP channel being read by each active mobile station. The retransmission of PP messages in the packet paging channel represented by arrows 27 and 28 means: the base station sends a PP message until the mobile station acknowledges (or until a specified time limit is exceeded). The mobile station having received the transmitted PP message sends this message back to the base station as a Packet Page Acknowledgement (PPA) according to arrow 29. The base station begins transmitting 30 after receiving confirmation that the call immediately following the PPA has been received. The resource requirements for downlink data transmission can also vary during the connection, in which case the base station subsystem allocates more gaps to the connection 31 (when the resource requirements increase) or releases part of the gaps (when the resource requirements decrease) 32. Notification of the change is advantageously sent to the mobile station by packet paging. Arrow 33 indicates the end of the transmission.

Fig. 5b illustrates the relationship of PP and PPA messages to downlink real-time data transmission to frame and superframe timing in one embodiment, where we again assume simultaneous FDD uplink and downlink transmissions with two frames 14 per superframe 19. After the base station has sent one PP message, the mobile station's first opportunity for acknowledgement is in the PPA gap of the next full UL frame. After receiving the PPA acknowledgement message, the base station may start the real-time DL data transmission in the next complete DL frame, it continues the real-time DL data transmission in the same gap in each subsequent DL superframe until the data source is exhausted (exhaustion not shown in the figure), which it detects when the mobile station finds the gap empty.

There may be several simultaneous connections between a given mobile station and a base station, also referred to as parallel connections, requiring real-time traffic in both the uplink and downlink directions. According to the preferred embodiment, the mobile station has a designated temporary logical identifier that distinguishes the mobile station from other mobile stations communicating with the same base station subsystem. For example, the identifier may be 12 bits in length. To distinguish parallel connections, a short (e.g., 2-bit) additional identifier may be utilized. When the mobile station wishes to start a parallel real-time connection during the assigned connection, it sends a capacity request to the base station subsystem in which it informs its temporary logical identifier and its additional identifier with a value different from the value of the additional identifier, which additional identifier describes the previously made real-time connection. Accordingly, the base station subsystem may start a new downlink parallel real time connection by sending a PP message in which it includes the logical identifier of the mobile station to which the message is destined and an additional identifier having a value different from the value of the additional identifier, which additional identifier describes the real time connection that has been made. On the basis of this additional identifier, each receiving station knows whether the sending station wishes to increase the capacity of some ongoing real-time connections or to start a new parallel connection.

Fig. 6a and 6b show non-real time uplink data transmission in the normal case. Arrow 34 corresponds to arrow 20 in fig. 4a, i.e. it represents data about the location of the next PPA slot transmitted in the Y slot of the designated downlink superframe. In one of the successive PRA intervals, the mobile station transmits a PRA message according to arrow 35 in which it identifies itself and informs it that it wishes to transmit at least non-real-time data. For example, the amount of data can be given in bits. In the next PAG gap, the base station informs the control gap location reserved for the uplink direction control channel in the downlink superframe as per arrow 36. In the next control gap, the base station sends the position in the uplink superframe of the first gap reserved for this connection according to arrow 37. In these gaps, the mobile station transmits uplink data as per arrow 38. For example, the uplink slots are combined such that 16 slots form one group. A control message for the mobile station information for the 16 slot positions is sent according to arrow 37. When the mobile station has sent 16 gap messages it receives a reply in the next control gap from the base station subsystem according to arrow 39, in which reply it is informed how the data was received in the gaps of the first group. If the base station has found a failure in some of the gaps, the mobile station must retransmit the data contained in those gaps. The control message, indicated by arrow 39, also contains gap location information belonging to the next group, in which case the uplink transmission continues in these gaps according to arrow 40. The transmission ends when the mobile station has sent all the desired information.

In the above case, the real-time service of fig. 4a is different from the non-real-time service of fig. 6a in the translation of the reservation message. In real-time traffic, designated radio resources (gaps) are reserved for continuous use of consecutive superframes. This means that the same reservation as that of the specified transmission rate (Xb/s) is used for the connection. In the non-real-time traffic case, the resources are reserved for the transmission of a specified number of bits or bytes, in which case the data transmission rate does not have to be constant. If there are many radio resources available, the base station subsystem may grant to the mobile station gaps that are close to each other in the messages represented by arrows 37 and 39. If the remaining traffic load of the base station is heavy or if the traffic load increases during a non-real-time connection, each superframe contains fewer idle gaps and the control messages depicted by arrows 37 and 39 grant the mobile stations gaps that are located far apart from each other in the data flow.

Fig. 6b shows the timing in the setup phase of a non real-time uplink connection. The illustrated convention is the same as in fig. 4b and 5 b. The mobile station begins operation when it finds the slot address of the next available PRA slot in the message sent in the Y slot from the base station. The mobile station sends a PRA message, which is assumed to arrive at the base station on the first attempt. In the next full downlink frame containing PAG slots, the base station sends a PAG message identifying NRT Control Slots (NCs) from the subsequent superframe. In the first NC, the base station sends a message in which the base station gives the address of the downlink ARQ gap and the address of the first granted uplink NRT traffic gap. The first granted uplink NRT traffic gap may be in the earliest next full uplink frame. The mobile station starts transmission in the assigned NRT traffic gap and the base station acknowledges transmission with an ARQ message and grants additional uplink NRT traffic gaps in the subsequent NC gap, which continues until all uplink NRT data has been sent.

The downlink non-real time data transmission is different from the data transmission described above and shown in fig. 7a and 7 b. When the base station subsystem wishes to transmit non-real time data of a mobile station, it first transmits a PP message according to arrow 41, which PP message contains gap location information intended for the uplink acknowledgement channel in the uplink superframe and first gap location information intended for the data to be transmitted in the downlink superframe. Arrow 42 represents a retransmission of the same PP message. When the mobile station informs in the PPA message that it is ready to receive, as per arrow 43, the base station subsystem transmits data in the previously informed slot as per arrow 44. The mobile station sends a positive or negative ARQ acknowledgement 45 of the received data, which acknowledgement may also contain measurements or similar information for the downlink power adjustment. If the downlink gap location or number changes, the base station subsystem informs the mobile station of that effect as per arrow 46. The transmission ends when the base station subsystem has sent all the desired data and has received the acknowledgement. The transmission may naturally end prematurely if the interference breaks the connection or the mobile station moves into an area covered by another base station.

In fig. 7b, the downlink non-real time transmission starts with a PP message sent by the base station in the PP gap of a certain downlink frame. The mobile station transmits the PPA message and optionally a null ARQ message in corresponding slots also identified in the PP message by transmitting the PPA message in the PPA slots identified in the PP message. The first downlink transmission will occur earliest in the next full downlink frame following the frame in which the base station received the PPA message for the mobile station. The mobile station acknowledges the downlink NRT transmission in its ARQ reply and the process continues until the non-real-time downlink data source is exhausted (not shown in the figure).

In the description of real-time services, in non-real-time connections, the same parallel connection principle explained above can be employed. However, since the radio resource control method according to the present invention is intended to be suitable for the case where all other idle gaps can be temporarily allocated to a given non-real-time connection, the parallel connection concept is less important for non-real-time traffic than for real-time traffic. In the case of non-real-time traffic, a non-real-time data transfer task can generally be completed before the next task is started.

The present invention does not require that the radio transmission capacity in uplink and downlink transmissions should be equal as suggested by the illustrated configurations of fig. 4b, 5b, 6b and 7 b. Rather, the present invention allows the base station subsystem (or corresponding device responsible for radio resource partitioning) to allocate gaps from uplink frames to downlink traffic or vice versa. For example, in electronic shopping, the electronic newspaper service and WWW (World wide web) browsing downlink capacity needs are much larger than the uplink capacity needs, which would result in unbalanced resource usage if the system capacity in the uplink and downlink could not be dynamically made asymmetric.

When the slot assignment routine decides to assign an uplink slot to downlink traffic, the base station subsystem tells the mobile station only in one PP message: the gap it should receive is in the uplink range (e.g., on the uplink frequency) and not in the used downlink range. In the opposite case, where one downlink gap is allocated to uplink transmission, PAG messages (in real-time traffic) or NC messages (in non-real-time traffic) from the base station subsystem allow the mobile station to use some nominal downlink gap(s) for its uplink transmission. However, care must be taken: changing the transmission direction in the middle of a superframe requires a guard interval between the two, which is twice the length of the maximum propagation delay in the cell. It is therefore proposed to combine the gaps into small blocks containing only gaps in the same transmission direction, so as not to waste time in a plurality of successive transmission direction changes. This limitation can be removed somewhat if the coverage area of a certain base station is so small that the length of the guard interval is negligible.

Fig. 8 shows the exchange of transmissions on the downlink band DL and the uplink band UL when some uplink transmission capacity is reserved for real-time downlink use. The illustrated conventional convention is the same as in fig. 4b, 5b, 6b and 7b, except that the additional cross-hatching now represents receiving a portion of the frames used for the downlink, and the cross-hatching represents receiving a portion of the frames used for the uplink. During the first superframe period, the base station sends a message in Y-slot Y1 telling the mobile station the location of the PRA slot PRA1 in the next full uplink frame. The mobile station uses the PRA opportunity to send a PRA message to the base station and generates a PAG message PAG1 in the next full downlink frame. This PAG message allocates a gap, tial, (or a set of gaps) to the mobile station. From that moment until the uplink real-time data resources are exhausted (not shown in the figure), the mobile station transmits its real-time data using this allocation periodically and in each superframe.

In the second frame of the second superframe, the base station transmits a PP message PP2 indicating its intention to transmit real-time downlink data to the mobile station. This PP message PP2 identifies a gap (or set of gaps) T2DL from the second frame in each subsequent uplink superframe. The mobile station transmits its PPA reply PPA2 in the next full uplink frame, after which the base station begins utilizing the identified (cross-hatched) portion T2DL of the uplink superframe for downlink real-time transmission. The uplink frequency band UL is now effectively Time Division Duplex (TDD). When the downlink transmission using gap T2DL ends (not shown in the figure), the uplink band may return to a pure uplink state or the base station subsystem may allocate uplink capacity for another downlink transmission. Naturally, there may be many uplink and downlink connections used simultaneously, either in the setup phase or in the teardown phase, but these are not shown in the figure for clarity of illustration.

Next we shall consider some additional duplex aspects. One option is to schedule uplink and downlink transmissions in each cell according to Time Division Duplexing (TDD). In that case, the transmissions in neither direction are consecutive in chronological order, but the transmissions in both directions alternate on a frame basis during each superframe. Only one frequency band is needed in the cell for both uplink and downlink directions. If the user uses a radio connection controlled according to the method of the invention for browsing the WWW (world wide web) or for another similar purpose, in which the data transmission required in one direction is more numerous than in the other direction (in WWW browsing the amount of downlink data transmission is 7-15 times the amount of uplink data transmission), time division duplexing can be designed such that in each superframe Y consecutive uplink frames follow X consecutive downlink frames (or X consecutive downlink frames follow Y consecutive uplink frames), where the integer X is related to Y > X. Also, the previously explained cross-allocation scheme may be introduced such that the base station subsystem may allocate downlink gaps for uplink transmissions even if there is a predetermined (fixed or dynamically varying) number of frames for each transmission direction, or vice versa.

Fig. 9 shows the exchange of transmissions in full time division duplex operation with all four possible combinations of uplink, downlink, real-time and non-real-time. Each row in the figure represents (symmetrically) a single frequency band for uplink and downlink transmission. The superframe 19 consists of two frames 14, where the first frame is for the Downlink (DL) and the second frame is for the Uplink (UL). The shaded portion of each frame contains the control gap. On the top row (uplink RT) the mobile finds the gap address of the next available PRA gap in the Y-gap downlink transmission, which is in the uplink frame of the same superframe it sends a PRA message and receives a PAG message in the next downlink frame that allocates a gap from the uplink frame. Thereafter, the mobile station uses this periodically occurring gap for uplink real-time transmission. On the second row (downlink RT), the base station sends a PP message identifying the downlink information gap from the next full downlink frame. The mobile station acknowledges with the PPA message after which the downlink real-time transmission begins.

On the third line (uplink NRT) of fig. 9, the mobile station sends a PRA message after finding a correct PRA slot address in the received Y slot message. In the downlink frame of the next superframe, the base station transmits one PAG message identifying one NRT control slot (NC) of the downlink frame from the third superframe. The base station then sends a message in the first NC in which it gives the downlink ARQ gap address and the first granted uplink NRT traffic gap address. The first gap of the granted uplink NRT traffic gap may be in the earliest uplink frame of the same superframe. The mobile station begins transmission in the assigned NRT traffic gap and the base station acknowledges the transmission with an ARQ message and grants additional uplink NRT traffic gaps in the subsequent NC gap. On the last row (downlink NRT), downlink non-real time transmission starts with a PP message sent by the base station in a PP gap. The mobile station transmits the PPA message in the PPA slots identified in the PP message and optionally also transmits a null ARQ acknowledgement in the corresponding slots identified in the PP message. The first downlink transmission will occur earliest in the downlink frame of the next superframe. The mobile station acknowledges the downlink NRT transmission in its ARQ acknowledgement and the process continues until the non-real-time downlink data source has been exhausted (not shown in the figure).

The radio resource control method according to the invention also provides the possibility to adjust the transmission power during a radio connection. Above we mention: the control slots contained in the superframes form one or several logical control channels, one bi-directional logical channel per connection may be referred to as an SCCH channel (system control channel), and in a preferred embodiment of the invention this channel comprises 1 slot per 16 superframes (1 200KHz slot in the example of time-frequency spacing space given above) in each active connection. This SCCH channel is used for the entire duration of the active data transmission period and can be used, for example, to send measurements on the power level, to design the mutual timing of the base station subsystem and the mobile station, to send information on the transfer to different base stations and to send commands from the base station subsystem to the mobile station, e.g., the base station subsystem can command the mobile station to enter a so-called sleep mode in which the mobile station is not active for a predetermined period of time to save power.

Another possibility provided by the method according to the invention for adjusting the power level of a mobile station is the common power control channel (PPCC) which is independent of the gap division in the frame. To accomplish this, each downlink frame includes a designated PPCC slot containing a designated number of power control bits for each possible slot in the corresponding uplink frame. To select the number of power control bits in the PPCC slots such that each slot has its own bits if the frames together consist of the smallest possible slot. When in fact this frame also contains large gaps, this arrangement is represented in fig. 10, using all those bits of the PPCC gap, called large gap region, in each large gap control. The PPCC gap 47 includes a first power control bit 48 and a second power control bit 49. If the corresponding uplink frame 50 includes only small gaps 51 and 52, the first power control bit 48 will control the first gap 51 and the second power control bit 49 will control the second gap 52. If the small gap block in the uplink frame is replaced by a large gap 53, the power control bits 48 and 49 control the same gap 53, which brings more solution or redundancy to the control. Thus, the PPCC gap structure can be independent of the gap structure of frames in the uplink channel. Similar control channel structures and principles can also be applied to other types of radio resource control connected to superframes. For example, the transmission timing point of each gap may be controlled by a similar process.

The previously proposed gap allocation principles can also be applied to existing TDMA systems like the GSM system or the IS-136 system to increase the data transmission capacity of a given radio connection. If several consecutive slots of each cyclically repeating frame are assigned to a single connection, the size of one allocation slot in a single frequency band will become larger in the chronological direction. Alternatively or additionally the connection may get gaps from uplink and downlink frames without the limitation that uplink frame gaps should only be used for uplink and downlink frame gaps should only be used for downlink. This means that the larger gap of the new allocation is actually made up of at least two independent regions in time-frequency space, with forbidden divider bands separating the nominal "uplink" from the "downlink" frequencies in a manner known in the art.

Fig. 12a shows a block diagram of a base station subsystem BSS according to the invention. The function of the BSS is controlled by the microcontroller 200. The micro-controller is connected to a slot allocator 201, and the allocator 201 performs slot allocation according to a calculation and/or algorithm. The different gap data is stored in memory as a gap reservation table 202. This table includes a table of uplink gaps 202a and downlink gaps 202b, indicating the size and status of each gap and any other possible parameters and to which mobile station a gap is allocated. Based on the slot allocation information received from the slot allocator 201, the micro-controller controls the transceiver 203 of the BSS to function in transmission and reception based on the allocation. The transceiver 203 may include a packet former/morpher (drformer)205 for forming transmitted data packets, after which a code is added to a code adder 206 if the code is one of the dimensions of the gap. Modulator 207 and RF transmitter 208 modulate the signals onto a radio frequency and form a carrier signal, which is then transmitted by antenna 204. Thus, block 205-208 forms the gap based on the gap allocation under the control of the microcontroller 200. In the receive block 205-208, the reverse function is performed under the control of the microcontroller 200. Block 200-202 may be part of a base station controller BSC or may be comprised in a base station BTS. Block 203-204 is part of the base station BTS.

Fig. 12b shows a block diagram of a mobile station subsystem MS according to the invention. The functions of the MS are controlled by the microcontroller 300. The microcontroller 300 is connected to a gap table 301, which gap table 301 stores information about the gaps allocated to the mobile station by the base station. This table includes an uplink gap and downlink gap table that represents the size and any other possible parameters. Based on the gap table 301, the microcontroller controls the transceiver 303 of the MS to function in transmission and reception according to the gap table. The transceiver 303 may include a packet former/deformer 305 for forming transmitted data packets, a code adder 306 adding a code later if the code is one dimension of a gap, a modulator 307 and an RF transmitter 308 modulating the signal onto radio frequency and forming a carrier signal, which is then transmitted by the antenna 304. Thus, block 305-308 forms a gap from the gap table under the control of the microcontroller 300. In the receive block 305-308, the reverse function is performed under the control of the microcontroller 300.

In the above description we have described a method of controlling radio resources with reference to some preferred embodiments. As will be apparent to those skilled in the art: the illustrated example is not meant to be limiting, but the invention can be modified according to the ordinary technical skill within the scope of the appended patent claims.

Claims

1. Method for controlling the actual radio resources in a radio system comprising a base station subsystem and several mobile stations radio-connected to the base station subsystem, characterized in that: this actual radio resource is divided into successive frames (14) in chronological order, said frames comprising two-dimensional slots (16, 17, 18) with variable data transmission capacity, wherein

The data transmission capacity of each gap is determined by the dimensions of this gap and at least one frame contains gaps of different data transmission capacities,

each gap represents a designated sharing of the actual radio resources contained in this frame,

-a number of gaps in at least one frame each being dynamically allocatable for use with a given radio connection for the duration of the frame,

-the first dimension of the gap is time and the second dimension of the gap is one of: time, frequency, code;

and the base station subsystem determines to allocate a gap to the radio connection based on:

-the data transmission requirements of the radio connection,

-a change in data transmission requirements of the radio connection, and

-the size and status of the gap occupancy.

2. A method according to claim 1, characterized in that: the gaps contained in the frame belong to at least two different allowed size classes depending on the respective amounts of actual radio resources, and for changing the gap structure of a frame, a predetermined integer number of gaps of a first size class may be replaced by a predetermined integer number of gaps of a second size class.

3. A method according to claim 2, characterized in that: the allowed number of size classes is 3, where the gap (16) of the largest size class is equal to two gaps (17) of the next largest size class or to ten gaps (18) of the smallest size class.

4. A method according to claim 2, characterized in that: the allowed number of size categories is 4, with the gaps of the largest size category equal to two gaps of the next largest size category, four gaps of the third largest size category, or eight gaps of the smallest size category.

5. A method according to claim 1, characterized in that: each frame is divided in the direction of the first dimension into a predetermined number of slots (15), and each slot is further divided into slots.

6. The method according to claim 5, characterized in that:

time-time division is employed such that each gap occupies the entire frequency range of the corresponding time slot, but the length of each gap in the time dimension depends on its data transmission capacity.

7. The method according to claim 5, characterized in that: time-frequency partitioning is employed such that each slot occupies the entire chronological duration of the corresponding time slot, but the width of each slot in the frequency dimension depends on its data transmission capacity.

8. The method according to claim 5, characterized in that: time-code division is employed such that each slot occupies the entire chronological duration of the respective time slot, but the data transmission capacity of each slot depends on the respective spreading code.

9. A method according to claim 1, characterized in that: consecutive frames of a predetermined non-negative integer form a superframe (19) such that in consecutive superframes, such frames that are located in a similar position from the beginning of the superframe correspond to each other for gap division if no change occurs in the data transmission requirements of the radio connection between superframes.

10. A method according to claim 9, characterized in that: each superframe contains a gap (I) for information transmission and a control gap (C) for implementing a logical control channel.

11. A method according to claim 10, characterized in that: a downlink signal includes a generic logical control channel (47) providing radio resource control for linking signaling to the gapped mode.

12. A method according to claim 10, characterized in that: each control gap (C) belongs to an allowed size class depending on the actual radio resource represented.

13. A method according to claim 1, characterized in that: according to the time division duplex scheme, a predetermined frequency band is used to transmit both the downlink gap and the uplink gap.

14. The method of claim 13, wherein: a predetermined non-negative integer number of consecutive frames form a superframe (19) and each superframe contains a first number of downlink frames and a second number of uplink frames.

15. The method of claim 13, wherein: the predetermined first frequency band is used to nominally transmit downlink gaps and the predetermined second frequency band is used to nominally transmit uplink gaps, but in response to asymmetric traffic conditions in the uplink and downlink aspects, the gaps are cross-allocated such that nominal downlink gaps are used to transmit uplink traffic or nominal uplink gaps are used to transmit downlink traffic.

16. A method according to claim 1, characterized in that: the base station subsystem maintains a reservation table to indicate the size and status of the gap occupancies in the frame and to maintain optimal utilization.

17. The method of claim 16, wherein: the base station subsystem evaluates the quality of at least one allocable gap and makes a decision to allocate or not allocate said gap to a connection based on the required transmission quality of said connection.

18. The method of claim 16, wherein: it comprises the following steps in the base station subsystem as a gap request reply,

-selecting either an uplink or a downlink frame storage,

-selecting a frame for storage,

-forming a set of candidate time slots from the selected frame store,

-applying a set of predetermined selection criteria to find the best candidate slot,

-checking the transmission quality provided by the selected best decision time slot, and

-making a decision to allocate a gap from the best candidate slot.

19. The method of claim 16, wherein: the base station subsystem also makes a decision to allocate a gap for a radio connection based on information contained in the reservation table of the neighbouring base station subsystem.

20. The method of claim 19, wherein: the base station subsystem allocates gaps based on the transmission power used by different mobile stations for communication such that a first mobile station communicating with a first base station using a low transmission power will be allocated a gap which coincides in chronological order with a gap allocated to a second mobile station communicating with a second base station using a high transmission power.

21. The method of claim 19, wherein: the base station subsystem allocates the gaps according to the type of communication used by the different mobile stations so that the circuit-switched and packet-switched connections have their own gaps in the reservation tables of the neighbouring base stations in the best position with respect to the total interference of the system.

22. Method for establishing an uplink radio connection between a base station subsystem and several mobile stations in a radio system comprising a base station subsystem and several mobile stations, in which radio system the actual radio resources are divided into frames (14) which continue in chronological order, characterized in that: the frame contains two-dimensional gaps (16, 17, 18) in the following cases,

the data transmission capacity of each gap is determined by the dimensions of this gap and at least one frame contains gaps of different data transmission capacity,

each slot represents a designated share of the actual resources contained in this frame,

-each of the number of gaps in each frame is dynamically allocatable for use with a given radio connection for the duration,

and the method comprises the steps of:

-sending a capacity request (21, 35) from the mobile station in an allowed uplink capacity request gap, in which request the mobile station indicates the actual amount of radio resources required by the radio connection, and

-making an allocation decision in the base station subsystem for the data transmission capacity of said two-dimensional gap as a response to said capacity request.

23. The method of claim 22, wherein: the position and number of allowed uplink capacity request gaps is not constant with respect to the frame structure and the base station subsystem sends a notification in a predetermined downlink gap indicating the position and number of said allowed uplink capacity request gaps.

24. A method according to claim 22, wherein the radio system additionally provides real-time and non-real-time data transmission services to the mobile station, characterized by: in order to reserve radio resources for the radio connection usage of the uplink call real-time data transmission service, the mobile station indicates in its capacity request (21) the required data transmission capacity.

25. The method of claim 24, wherein: the mobile station additionally indicates in its capacity request a predetermined set of parameters describing the required quality of the radio connection.

26. The method of claim 24, wherein: when the data transmission capacity needs to be increased during an ongoing radio connection of the uplink real-time data transmission service, the mobile station sends a capacity request (24) to the base station subsystem, in which request it indicates the required additional data transmission capacity.

27. The method of claim 24, wherein: the mobile station leaves at least one unused allocation gap when the data transmission capacity requirement decreases during an ongoing radio connection of the uplink real-time data transmission service.

28. The method of claim 24, wherein: each mobile station has a certain temporary logical identifier to distinguish it from other mobile stations operating under the same base station subsystem, and in order to reserve radio resources for radio connection usage of the parallel uplink real time data transmission service, the mobile station sends a capacity request to the base station subsystem, in which request the mobile station indicates:

-a temporary logical identifier of the same,

-required parallel data transmission capacity, and

-an additional identifier which distinguishes the parallel radio connection from other ongoing radio connections carrying real-time data transmission traffic.

29. A method according to claim 22, wherein the radio system additionally provides real-time and non-real-time data transmission services to the mobile station, characterized by: in order to reserve radio resources for radio connection usage of uplink non-real time data transmission traffic, a mobile station indicates in its capacity request (21) an amount of data to be transmitted.

30. The method of claim 22, wherein: the base station subsystem has the freedom to direct the required radio connection to any available gap in its allocation decision and after the allocation decision the base station subsystem sends the granted gap indication to the mobile station in a predetermined downlink access grant gap.

31. Method for establishing a downlink radio connection between a base station subsystem and mobile stations in a radio system comprising one base station subsystem and several mobile stations, in which radio system the actual radio resources are divided into successive frames (14) in chronological order, characterized in that the frames contain two-dimensional gaps (16, 17, 18), in which case,

-each of the plurality of gaps in each frame is dynamically allocatable for use with a given radio connection for the duration of the frame,

and the method comprises the steps of:

-making an allocation decision in the base station subsystem in response to a need for detection of a new downlink radio connection indicative of an actual amount of radio resources required by a radio connection,

-sending a paging message (27, 28, 41, 42) from the base station subsystem to the mobile station informing of the downlink gap position allocated to the radio connection in said allocation decision,

-sending a page acknowledgement message from the mobile station in response to detecting the page message, and

-initiating downlink transmission from the base station subsystem in response to detecting the paging acknowledgement message.

32. A method according to claim 31, wherein the radio system additionally provides real-time and non-real-time data transmission services to the mobile station, characterized by: in order to form a radio connection for downlink real-time data transmission services, the base station subsystem indicates in a paging message (27, 28) the relationship of the gap position allocated to the periodic repetition of this radio connection to the frame structure.

33. The method of claim 32, wherein: when the data transmission capacity requirement increases during an ongoing radio connection for downlink real-time data transmission services, the base station subsystem makes additional gap allocation decisions and sends a paging message (27, 28, 41, 42) to the mobile station informing the location of additional downlink gaps allocated to the radio connection.

34. The method of claim 32, wherein: when the data transmission capacity requirement decreases during an ongoing radio connection of a downlink real-time data transmission service having several allocation gaps, the base station makes a decision relating to a gap reallocation of at least one allocation gap and leaves the corresponding gap unused.

35. The method of claim 32, wherein: each mobile station has a designated temporary logical identifier to distinguish the mobile station from other mobile stations operating in the same base station subsystem, and in order to reserve radio resources for radio connection usage of the parallel downlink real-time data transmission service, the base station subsystem sends a paging message to the mobile station in which it indicates:

-a temporary logical identifier of the mobile station,

-regularly repeated gap positions allocated to parallel radio connections, and

an additional identifier and distinguishes the parallel radio connection from other ongoing radio connections carrying real-time data transmission traffic.

36. A method according to claim 31, wherein the radio system additionally provides real-time and non-real-time data transmission services to the mobile station, characterized by: in order to form a radio connection for downlink non-real time data transmission services, the base station subsystem indicates in a paging message (41, 42) the relation of the first gap location for non-real time data transmission services to the frame structure and informs about a change in the gap location or number allocated to non-real time data transmission services during the connection, and the base station subsystem informs about the new location or number of gaps by sending a new paging message.

37. A base station subsystem for a radio communication system having the base station subsystem and a mobile station, comprising:

a microcontroller (200) for controlling the functions of the base station subsystem;

the gap distributor (201) is connected with the microcontroller and used for carrying out gap distribution according to calculation and/or algorithm;

a transceiver (203) controlled by the microcontroller to function in transmission and reception according to slot allocation information received from the slot allocator.

38. A base station subsystem according to claim 37, characterized by: it also comprises means for maintaining a reservation table to indicate the size and status of the gap occupancies in the frame and to maintain optimal usage.

39. A base station subsystem according to claim 38, characterized by: it further comprises means for communicating with the neighbouring base station subsystem regarding the reservation table.

40. A base station subsystem according to claim 37, characterized by: to establish an uplink connection, it further comprises means for:

-generating a general access gap location notification and sending it to all mobile stations in a predetermined downlink gap in order to advise the mobile stations to send a capacity request in the notified access gap,

-receiving and translating a capacity request from a mobile station,

-making a gap allocation decision, allocating time slots to the radio connection requested and identified in the capacity request, and

-generating access grant messages and selectively sending them in predetermined gaps to those mobile stations whose capacity requests have been granted in the gap allocation decision.

41. A base station subsystem according to claim 37, characterized by: for establishing a downlink connection, it further comprises means for

-generating a paging message and transmitting the message selectively at predetermined intervals to those mobile stations which are to establish a downlink connection, said paging message indicating at least one allocated downlink interval,

-receiving and interpreting a page acknowledgement message from the mobile station, and

-directing downlink transmissions to the allocated downlink gaps indicated in the paging message.

42. A mobile station for use in a radio communication system having a base station subsystem and the mobile station, comprising:

a microcontroller (300) for controlling functions of the mobile station;

a gap table (301) connected to the microcontroller for storing information about gaps allocated to the mobile station by the base station;

a transceiver (303) controlled by the microcontroller to function in transmission and reception according to a gap table.

43. The mobile station according to claim 42, further comprising means, for establishing said link connection, for:

-receiving and interpreting an access slot location notification sent from the base station subsystem,

-generating a capacity request and sending this request in the access slot identified in the access slot location notification,

-receiving and interpreting access grant messages from the base station subsystem identifying at least one grant gap, and

-directing the information transmission directly to the at least one granted gap.

44. The mobile station according to claim 42, characterized in that, for establishing the downlink connection, it further comprises means for:

-receiving and interpreting a paging message sent from the base station subsystem, said paging message indicating at least one allocated downlink gap,

-generating a paging acknowledgement message and transmitting it in an acknowledgement gap, and

-receiving and interpreting a downlink transmission in said at least one allocated downlink gap.

45. The mobile station of claim 44, wherein: it also includes means for identifying an acknowledgment gap based on information contained in the paging message.

46. A radio communication system having a base station subsystem according to claim 37 and a mobile station according to claim 42.