HK1066341A - Adaptive uplink/downlink timeslot assignment in a hybrid wireless time division multiple access/code division multiple access communication system - Google Patents

Description

Adaptive uplink/downlink time slot allocation for hybrid wireless TDMA/CDMA systems

Background

The present invention relates generally to resource allocation in wireless hybrid time division multiple access/code division multiple access communication systems, and more particularly to the allocation of uplink time slots and downlink time slots in such systems.

Fig. 1 illustrates a wireless communication system having a plurality of base stations 30₁-30₁₁. Each base station 30₁Are all associated with User Equipment (UE)32 within its operating area or coverage area₁、32₃、32₄Communication is performed. Slave base station 30₁To the UE32₁Is referred to as a downlink communication,slave UE32₁To the base station 30₁Is referred to as uplink communication.

In addition to communicating over different frequency spectrums, spread spectrum Code Division Multiple Access (CDMA) systems may communicate multiple times over the same frequency spectrum. The plurality of communication signals are identified by their respective chip codes (encodings). To make more efficient use of spread spectrum, some hybrid Time Division Multiple Access (TDMA)/CDMA systems use relay frames 34 (shown in FIG. 2), which relay frames 34 are divided into time slots 36₁-36_nFor example 15 slots. In a Time Division Duplex (TDD) system using CDMA, one time slot can be used for downlink communication or uplink communication in only one base station coverage area alone. In such a system, communication is carried out using a selected code in selected time slots 36₁-36_nIs sent. Thus, one frame 34 can be simultaneously divided into time slots 36₁-36_nAnd encoding the identified multiple communications. The use of a single code in a single time slot with a spreading factor of 16 is referred to as a resource unit. One or more resource units may be allocated for a communication based on the bandwidth requirements of the communication.

One problem with such systems is cross cell interference, as shown in figure 3. Base station 30 of the second base station coverage area₂UE32 covering area to second base station in a certain time slot₂A downlink communication 40 is sent. In the same time slot, the UE32 of the first base station coverage area₁An uplink communication 38 is also sent out. The uplink communication 38 may be by the base station 30 of the first base station coverage area₁Received with an unacceptable level of interference. Although the base station 30 of the second base station coverage area₂UE32 farther from the first BS-coverage area₁But a base station 30 in the coverage area of the second base station₂May still be in the base station 30 of the first base station coverage area₁Generating unacceptable interference.

Also shown in FIG. 3 is UE32₁，32₂Cross interference between them. From UE32 in a first base station coverage area₁In the upstream ofThe link signal 38 will be to the UE32 in the second base station coverage area₂Downlink communications 40 received in the same time slot produce unacceptable levels of interference because they are very close.

Therefore, there is a need to reduce cross-cell interference.

Disclosure of Invention

A particular cell of a hybrid TDMA/CDMA communication system has a base station and a plurality of user equipments. Time slots with unacceptable interference to the uplink are estimated, time slots with unacceptable interference to the downlink are estimated, and an availability list is generated. The availability list identifies available uplink and downlink time slots that have acceptable interference levels. Uplink and downlink timeslots are allocated using the availability list.

Drawings

FIG. 1 is a wireless spread spectrum CDMA system;

FIG. 2 shows time slots in a relay frame;

figure 3 illustrates cross base station coverage area interference;

FIG. 4 is an availability list;

FIG. 5 is a flow chart of generating an availability list using base station-base station (BS-BS) and user equipment-user equipment (UE-UE) interfering BS footprints;

FIG. 6 is an example of a cross-interference cell list;

FIG. 7 is a table showing virtual slot assignments for each BS-cell;

fig. 8 is a list of availability of bs cell 1 constructed using fig. 6 and 7;

FIG. 9 is a flow chart of generating an availability list using only BS-BS interfering BS cells;

FIG. 10 is a BS-BS cross interference list diagram;

FIG. 11 is a flow chart of generating an availability list using only UE-UE interfering BS cells;

FIG. 12 is a UE-UE cross interference list;

FIGS. 13 and 14 are flow diagrams for determining timeslot availability using base station and UE interference measurements;

FIG. 15 is an illustration of an availability list for a user device;

FIGS. 16 and 17 are flow diagrams for determining timeslot availability using interference measurements only;

FIGS. 18, 19 and 20 are flow diagrams for determining availability of a time slot using a hybrid approach;

FIG. 21 is a flow chart of a method of time slot allocation;

FIG. 22 is a flow chart of an update of an availability list;

FIG. 23 is an updated table of FIG. 7;

figure 24 is an updated availability list based on cell 7 of figure 23;

FIG. 25 is a centralized architecture embodiment;

FIG. 26 is a dispersion architecture embodiment.

Detailed Description

Although the slot allocation is described below for a TDD/CDMA system, the same slot removal procedure and availability list may also be applied to a hybrid TDMA/CDMA system in which uplink and downlink communications are made in the same slot of a base station coverage area.

Fig. 4 shows an availability slot list 76. Along the horizontal axis, the individual time slots numbered S1, S2. The uplink and downlink for each base station coverage area are listed along the vertical axis with subscripts to its associated base station reference numbers. Each row indicates the availability of uplink or downlink time slots in a base station coverage area. The unavailable slots are denoted by "X" and the available slots are unmarked.

Fig. 5 shows a step of generating the availability list, which can be described with reference to fig. 6, fig. 7 and fig. 8. First, cross interference between each pair of base station coverage areas is measured. First, the base station 30 is determined in step 77₁-30₁₁Base station 30₁-30₁₁(BS-BS) interferes with the base station coverage area. The BS-BS interference coverage area is a base station 30₁-30₁₁Interferes with another base station 30₁-30₁₁Is received from the base station coverage area.

Each cell determines its BS-BS interfering cells by estimating interference from other cells. One method is to utilize each base station 30₁-30₁₁The predicted link gain between estimates BS-BS interfering base station coverage. In step 77, if the estimated interference value exceeds a certain threshold, the coverage area of the base station is deemed to be a BS-BS interfering base station coverage area. Based on the threshold comparison, the BS-BS interfering cells are determined and stored in a cross interfering cell list 84 as shown in fig. 6. The vertical axis of the cross-interference cell list 84 contains the various cells and the horizontal axis contains the potential cross-interference cells. In step 79, the corresponding boxes are filled with "I" identifying the cell that constitutes BS-BS interference with another cell. For example, the first row, second column box is labeled "I" because the communications of cell 2 cross-interfere with cell 1. These boxes are labeled "X" because one base station coverage area will not interfere with itself.

In addition, in step 78, the UE32 is addressed to it₁-32_nMay interfere with other UEs 32₁-32_nIs determined. Since the UE32₁-32_nIs relatively low, so that the respective UE-UE interfering base station coverage areas are very close geographically, e.g. adjacent to each other. One UE32₁May interfere with reception by a UE in a neighboring base station coverage area, as shown in fig. 3. Since coverage areas of base stations in close geographic proximity may have UEs 32 that may interfere with each other₁-32_nAnd therefore these base station coverage areas are also listed as interfering base station coverage areas. In step 79, as shown in fig. 6, UE-UE interfering cells that are not BS-BS interfering cells are identified with "I".

In step 78, a potential cross interfering cell for each cell is determined using the cross interfering cell list 84. For a particular cell in the vertical axis, the cells marked as "I" or "I" in the corresponding row are all cross-interfering cells. For example, cell 1 may experience potential cross interference from cells 2, 3, 5, 6, 9, and 10. A slot assignment is then determined for each cross interfering base station coverage area. For example, downlink time slots 1 and 2 and uplink time slot 9 are allocated to base station coverage area 2 using the virtual time slot allocation of table 86 in fig. 7. In step 80, for each downlink timeslot allocated in a cross interfering base station coverage area, its corresponding uplink timeslot is eliminated. Using fig. 6, 7 and 8 to illustrate, as shown by an "X" in the availability list 88 of cell 1 of fig. 8, for cell 1, cell 2 is assigned downlink time slot 1 to eliminate time slot 1 from the available uplink time slots of cell 1.

In step 82, for each uplink timeslot allocated to a cross-interfering base station coverage area, its corresponding downlink timeslot is eliminated. To illustrate with cell 1 as an example, the uplink time slot 9 of cell 2 would eliminate time slot 9 from the possible downlink time slots of cell 1, as shown in the availability list 88 of cell 1. After the corresponding time slots have been eliminated due to cross interference with the cell sites, an availability list 76 is generated for each cell site in step 90. Thus, the uplink and downlink time slots used in each cross interfering cell will not be available, thereby reducing cross cell interference.

To relax the allocation conditions, only BS-BS interfering cells or only UE-UE interfering cells may be considered. These methods may free up more resources in each base station coverage area. However, loose criteria can cause unacceptable levels of interference to some users.

Fig. 9 is a flow diagram of generating an availability list using only BS-BS interfering cells. In step 122, each BS-BS interfering BS coverage area is identified, and a BS-BS cross interference list 132, such as the list shown in fig. 10, is generated. If a cell uses a timeslot for the uplink, its corresponding downlink timeslot is eliminated in step 126 and is no longer used for the BS-BS interfering cells. Conversely, if a cell uses a time slot for the downlink, then its corresponding uplink time slot will be eliminated in step 128 and no longer used for the BS-BS interfering cell. Then, in step 130, a list of available time slots for each base station coverage area is generated. While this approach more aggressively utilizes system resources, it can nevertheless expose some users to unacceptable downlink interference.

Fig. 11 is a flow chart of generating an availability list using only UE-UE interfering cells. In step 134, the interfering bss are identified, and a UE-UE cross interference list 142, such as the one shown in fig. 12, is generated. If a cell uses a timeslot for the uplink, its corresponding downlink timeslot is eliminated in step 136 and is no longer used for the UE-UE interfering cell. Conversely, if a cell uses a timeslot for the uplink, then its corresponding downlink timeslot is eliminated in step 138 and is no longer used for the BS-BS interfering cells. Then, in step 140, a list of available time slots for each base station coverage area is generated. This approach may cause unacceptable uplink interference to some users.

Another method of determining available time slots employs interference measurements of the time slots, such as by Interfering Signal Code Power (ISCP). Interference measurements may be made at the base station 30₁-30₁₁、UE 32₁-32_nEither in combination or in both locations.

FIG. 13 is a block diagram of each UE32 determined using base station and UE interference measurements₁-32_nA flow chart of available time slots. In step 144, at the base station 30, for a particular cell site₁The interference level in each time slot is measured. In step 146, each UE32 of the BS-overlay area₁，32₃-32₄The interference level in each time slot is also measured. The slot interference measurements measured by the base station are used to determine the availability of uplink slots. The availability of downlink time slots is then determined on a per-UE basis (UE-specific basis).

For the uplink, if the interference measured by the base station in a time slot exceeds a threshold, the corresponding uplink time slot is eliminated in step 148. For the downlink, if the UE32₁，32₃，32₄If the interference measurement value of a certain UE exceeds a threshold, the UE will eliminate the use of the time slot in the downlink in step 150. Then, in step 152, an availability list 154 is generated, which indicates the available uplink time slots and the available downlink time slots for each UE, as shown in fig. 15.

Even if two base station coverage areas are adjacent to each other, the particular UE32 in a base station coverage area₁-32_nMay also be located further apart. Illustrated using fig. 1, cell 1 and cell 2 are adjacent to each other, however, UE32₄At a greater distance from the base station coverage area 2. Therefore, if radicalUE32 in station coverage area 2₂Using a certain time slot for uplink, it is highly likely not to interfere with the UE32₄Is received. Of course, the UE32₂May interfere with the UE32₁Is transmitted in the downlink. Thus, a more aggressive resource allocation may be achieved using the availability list 154 for the UE. One disadvantage is the need for increased signalling. Due to the mobility of the UE and the reallocation of other base station coverage areas, the interference measurements must be updated and signaled to the base station 30 frequently₁-30₁₁。

Fig. 14 is a flow diagram for determining available time slots for non-UEs using base station and UE interference measurements. In step 144, the base station 30₁Interference in each time slot is measured. In step 146, each UE32₁，32₃，32₄Interference in each time slot is also measured. For the uplink, if the interference value measured by the base station in a time slot exceeds a threshold, the time slot is eliminated in step 148. For the downlink, if the measured interference value in a time slot of any UE in the coverage area of the base station exceeds a threshold, the corresponding downlink time slot is eliminated in step 156. A list 88 of the availability of each cell, such as the list shown in fig. 8, is then generated using the eliminated time slots. The lack of UE interference measurements is not critical to the allocation of resource units, since the UE measurements are effectively combined.

Fig. 16 and 17 are flow diagrams for determining available timeslots using only UE interference measurements. In step 160, the UEs in one coverage area of the base station measure the interference in each time slot. For the uplink, if any UE interference measurement exceeds the threshold, its corresponding uplink slot is eliminated in step 160. Alternatively, to reduce the number of uplink slots to cancel, only slots that cause unacceptable interference to most UEs are cancelled from the uplink in step 160. If only a few UEs report unacceptable interference, they can be considered to be at the edge of the cell and not representative of the entire cell.

Using an assignment method for UEs as shown in FIG. 16, each UE32₁，32₃，32₄Each own set of available downlink time slots, such as the time slots shown in fig. 15. In step 164, if the UE32₁，32₃，32₄Where the interference measurement for a certain UE in a downlink time slot exceeds a threshold, the time slot is cancelled. An availability list 150 for the UE is then generated in step 166.

Fig. 17 illustrates a method for a non-UE. If the interference measurement for any or most of the UEs in the time slot exceeds a threshold, the downlink time slot is eliminated in step 168. At this point, an availability list 88 of the entire base station coverage area, such as the list shown in fig. 8, may be generated.

Fig. 18, 19 and 20 are slot availability determination methods using hybrid BS-BS interference, UE-UE interference and interference measurement methods. Fig. 18 and 19 use BS-BS interfering cells and UE interference measurements. In step 172, a determination is made as to the BS-BS interfering base station coverage area. In step 174, each UE32₁，32₃，32₄Interference in each time slot is measured. If a BS-BS interfering cell uses a time slot for the downlink, its corresponding uplink time slot is eliminated in step 176.

Downlink availability is determined on a per-UE or collective basis. Using the UE-by-UE approach shown in FIG. 18, each UE32₁，32₃，32₄Each slot interference measurement is compared to a threshold. If the measured value for a time slot exceeds the threshold, the time slot is eliminated from use by the UE32 in step 178₁，32₃，32₄The downlink of (2). Thereafter, an availability list 150 for the UE, such as the list shown in fig. 15, is generated in step 180.

Using the collective method of fig. 19, if any UE time slot interference measurement exceeds a threshold, that time slot is eliminated from use in the downlink of the base station coverage area in step 182. An availability list 88, such as the list shown in fig. 8, is then generated in step 184.

Fig. 20 uses UE-UE interfering cells and base station interference measurements. In step 186, a base station 30 of a base station coverage area₁The interference level in each time slot is measured. In step 188, the areas of UE-UE interfering base station coverage are identified. In step 190, for the uplink, if the interference of the uplink time slot exceeds a threshold, the uplink time slot is eliminated. In step 192, for the downlink, if a certain UE-UE interfering base station coverage area uses one slot for the uplink, its downlink slot is eliminated. An availability list 88, such as the one shown in fig. 8, is then generated based on the eliminated time slots.

For sectorized base station coverage, a cross interference list and availability list 84 is formed for each sector within the base station coverage area. Then, cross-interference among all sectors in the coverage area of the base station is determined. Although the following discussion focuses on non-sector base station coverage areas, the same approach is applicable to sector base station coverage areas where time slot allocation is done on a per sector basis rather than on a per base station coverage area basis.

Each base station 30₁-30_nThe availability list 76 is used and the steps shown in fig. 21 are taken to allocate the time slots to support its communications. First, in step 92, a request is made to allocate one or more additional time slots. The corresponding available time slot is then allocated with reference to the availability list 76 of that base station. Using the availability list 88 of FIG. 8 to illustrate, the base station 30₁It is required to simultaneously allocate one additional downlink time slot and one uplink time slot. The available uplink time slots are time slots 4 and 7-16 and the available downlink time slots are time slots 1-3, 5, 6, 8, 10-13 and 16. At this time, one uplink time slot and one downlink time slot will be allocated from the respective available downlink time slots and uplink time slots. If a needle is usedTo the UE's availability list 150, the downlink allocation will be in terms of the UE32 requiring downlink resource units₁-32_nThe basis is.

Due to the base station 30₁-30_nThe time slots need to be dynamically allocated and released according to changing uplink/downlink requirements, and therefore the information in the availability list 76 needs to be updated. For methods using interference measurements, the updating of the information is done by updating the measurement values and the list.

For the BS-BS and UE-UE methods, this step is shown in fig. 22. First, in step 96, the cross-interference cell coverage area corresponding to each allocated or released timeslot is identified. In step 98, for each downlink time slot allocated, the corresponding uplink time slot in its cross interfering base station coverage area is eliminated. Otherwise, if an uplink timeslot is allocated, the corresponding downlink timeslot in its cross interfering base station coverage area is eliminated in step 100. Illustrated with reference to fig. 23 and 24, the base station 30 associated with the cell site 6 is shown as table 106 in fig. 23₆Time slot 7 is allocated for downlink (' D)^*") time slot 8 is allocated for the uplink (" U ")^*"). The cross interfering cells are cells 1, 2, 5 and 7. As shown in the availability list 107 of base station coverage area 7 in fig. 24, the corresponding uplink time slot 7 and the corresponding downlink time slot 8, both marked with an "X", are eliminated^*”。

In step 102, if a certain downlink time slot is released, its corresponding time slot in the cross interfering base station coverage area is released for uplink unless it is not available for other reasons (e.g., being used as a downlink time slot in another cross interfering base station coverage area). For example, even if slot 6 of cell 6 is released (indicated by "D" in table 106)^**"identity"), uplink time slot 6 of base station coverage area 1 is still not available. The reason is that: cell 9 is a cross-interfering cell of cell 1, which is also using downlink time slots 6. In contrast, for cell 7, the downlinkThe release of link time slot 6 allows the base station coverage area to be released for uplink communications as indicated by "R" in the availability list 108 of base station coverage area 7. In step 104, if a certain uplink time slot is released, its corresponding time slot in the cross interfering base station coverage area is released for downlink unless it is not available for other reasons.

Fig. 25 shows a method for uplink/downlink timeslot assignment using a centralized architecture. The Radio Network Controller (RNC)110 has a resource allocation means 116 that allocates or releases time slots according to user requirements. If a time slot is to be allocated, the resource allocation means 116 in the RNC 110 will allocate an appropriate time slot using the availability list 76 stored in its memory 117 in accordance with the steps shown in fig. 21. Selected time slot and channel coding pass through node B time slot allocation and release 112₁-112_nTransmission to base station 30₁-30_NAnd UE32₁-32_N. To release a slot, the RNC resource allocator 116 releases the slot and updates the availability list 76. Thus, the availability list 76 is centrally updated at the RNC 110.

Fig. 26 shows an uplink/downlink slot allocation method using a decentralized architecture. Wherein each contact B122₁-122_NAll own slot controller 120₁-120_n. When a time slot allocation and release device 112₁-112_nThe time slot controller 120 of the node B requests a time slot for communication₁-120_nWill be stored in its memory 121₁Selects an appropriate time slot from the self availability list 76. The stored availability list 76 may contain only the available time slots for the node B's base station coverage area to reduce the size of the list. Conversely, the stored availability list 76 may also contain the availability of all base station coverage areas of the RNC. This decentralized approach may enable faster updates.

The selected time slot is allocated by the time slot and released by the device 112₁-112_nTo be assigned to the communication. If it is needed to do moreNew list 76, node B122₁-122_nUpdating its own list 76. The allocated and released time slots will also be sent to RNC 110. RNC 110 then sends corresponding time slot update information to other base station coverage areas. The time slot information contains an updated availability list 76 or only change information for the list 76. Controller 120 of each cell if change information is transmitted only₁-120_nWith this information updating its own availability list 76. The type of slot information sent depends on the processing and signaling requirements of the system.

The allocation of uplink/downlink time slots may be adapted to systems supporting different signaling rates. For systems that support only slow network signaling, the allocated slot information is updated on a day-by-day basis using a statistical analysis of the uplink/downlink demand. Since the effect of speeding up the update is better in view of the change of the communication traffic in the day, it is better to adopt a faster update. For moderate speed network signaling, the slot information is periodically updated at intervals of a fraction of an hour to several hours. Moderate speed network signaling also utilizes statistical analysis, but for a shorter time period. For fast network signaling, the assigned time slots are updated on a per-call basis or on a frame basis. Each time a slot is allocated or released, the corresponding list is updated. Fast network signaling allocates time slots on an as needed basis. Therefore, it can more efficiently utilize system resources.

Claims (42)

1. A method for allocating timeslots to a particular cell in a hybrid time division multiple access/code division multiple access communication system having a plurality of cells including said particular cell and other cells, the method comprising:

determining potentially interfering ones of the other base station coverage areas that potentially interfere with the particular base station coverage area;

for each time slot, eliminating the time slot in uplink communications if the first type of potentially interfering base station coverage area uses the time slot for downlink communications;

for each time slot, eliminating the time slot in the downlink communication if the second type of potentially interfering base station coverage area uses the time slot for uplink communication;

allocating a time slot for an uplink communication of said particular base station coverage area using non-uplink cancellation time slots; and

a time slot is allocated for a downlink communication of the particular base station coverage area using non-downlink cancellation time slots.

2. The method of claim 1 wherein the first type of potential interfering cells are base station to base station interfering cells of the particular cell.

3. The method of claim 2 wherein the base station-to-base station interfering cell is determined using link gain between base stations.

4. The method of claim 1 wherein the first and second types of potentially interfering cells are base station to base station interfering cells of the particular cell.

5. The method of claim 1 wherein the second type of potentially interfering cell is a user equipment-user equipment interfering cell of the particular cell.

6. The method of claim 5, wherein the user equipment-user equipment interfering cell is a cell that is geographically close to the particular cell.

7. The method of claim 6 wherein the geographically proximate base station coverage areas are adjacent base station coverage areas.

8. The method of claim 1, wherein the first and second types of potentially interfering cells are user equipment-user equipment interfering cells of the particular cell.

9. The method of claim 1, wherein the hybrid time division multiple access/code division multiple access communication system is a time division duplex communication system employing code division multiple access.

10. A hybrid time division multiple access/code division multiple access communication system, comprising:

a plurality of base station coverage areas, including a specific base station coverage area and other base station coverage areas;

the specific base station coverage area includes:

means for determining each potentially interfering cell of the other cells potentially interfering with the particular cell;

means for eliminating a time slot in uplink communication if the time slot is used for downlink communication by a first type of potentially interfering base station coverage area;

means for allocating a time slot for an uplink communication using non-uplink cancellation time slots; and

means for allocating a time slot for a downlink communication using non-downlink cancellation time slots.

11. The system of claim 10 wherein the first type of potential interfering cells are base station to base station interfering cells of the particular cell.

12. The system of claim 11 wherein the base station to base station interfering cells are determined using link gains between base stations.

13. The system of claim 10 wherein the first and second types of potentially interfering cells are base station to base station interfering cells of the particular cell.

14. The system of claim 10 wherein the second type of potentially interfering cell is a user equipment-user equipment interfering cell of the particular cell.

15. The system of claim 14 wherein the user equipment-user equipment interfering cell is a cell that is geographically close to the particular cell.

16. The system of claim 15 wherein the geographically proximate base station coverage areas are adjacent base station coverage areas.

17. The system of claim 10 wherein the first and second types of potentially interfering cells are user equipment-user equipment interfering cells of the particular cell.

18. The system of claim 10, wherein the hybrid time division multiple access/code division multiple access communication system is a time division duplex communication system employing code division multiple access.

19. A hybrid time division multiple access/code division multiple access communication system, comprising:

a plurality of base station coverage areas, including a specific base station coverage area and other base station coverage areas;

a radio network controller associated with the particular base station coverage area, comprising:

a resource allocation means for determining each potentially interfering cell of other cells potentially interfering with said particular cell; for each time slot, eliminating the time slot in uplink communications if the first type of potentially interfering base station coverage area uses the time slot for downlink communications; and for each time slot, eliminating the time slot in the downlink communication if the second type of potentially interfering base station coverage area uses the time slot for uplink communication; and

a node B associated with said particular base station coverage area comprising an allocation and release means for allocating an uplink communication using non-uplink cancellation time slots and for allocating a downlink communication using non-downlink cancellation time slots.

20. The system of claim 19 wherein the first type of potential interfering cells are base station to base station interfering cells of the particular cell.

21. The system of claim 20 wherein the base station to base station interfering cells are determined using link gains between base stations.

22. The system of claim 19 wherein the first and second types of potential interfering cells are base station to base station interfering cells of the particular cell.

23. The system of claim 19 wherein the second type of potentially interfering cell is a user equipment-user equipment interfering cell of the particular cell.

24. The system of claim 23 wherein the user equipment-user equipment interfering cell is a cell that is geographically close to the particular cell.

25. The system of claim 24 wherein the geographically proximate cell sites are adjacent cell sites.

26. The system of claim 19 wherein the first and second types of potentially interfering cells are user equipment-user equipment interfering cells of the particular cell.

27. The system of claim 19, wherein the hybrid time division multiple access/code division multiple access communication system is a time division duplex communication system employing code division multiple access.

28. A method for allocating time slots in a particular cell of a hybrid time division multiple access/code division multiple access communication system, the particular cell including a base station and a plurality of user equipments, the method comprising:

(a) estimating a time slot having unacceptable interference to uplink communications associated with the base station;

(b) estimating a time slot having unacceptable interference to downlink communications associated with the user equipment;

(c) generating an availability list indicating available uplink time slots and downlink time slots having acceptable interference levels; and

(d) uplink and downlink timeslots are allocated using the availability list.

29. The method of claim 28, wherein step (a) comprises measuring the interference level in each time slot at the base station and comparing the measured level to a threshold to estimate unacceptable interference.

30. The method of claim 28 wherein step (a) comprises determining base station to base station (BS-BS) cross interfering cells associated with the particular cell and estimating unacceptable interference if any of the determined BS-BS interfering cells uses a slot for downlink.

31. The method of claim 28, wherein step (b) comprises measuring, by each user equipment, an interference level in each time slot and comparing the measured level to a threshold to estimate unacceptable interference.

32. The method of claim 28 wherein step (b) comprises determining user equipment-user equipment (UE-UE) cross interfering cells with respect to the particular cell and estimating unacceptable interference in a particular time slot if any of the determined UE-UE interfering cells uses the particular time slot for uplink.

33. A hybrid time division multiple access/code division multiple access communication system, the system comprising:

a particular cell site, comprising:

a base station and a plurality of user equipments;

first means for estimating time slots having unacceptable interference to the base station;

second means for estimating time slots having unacceptable interference to downlink communications associated with the user equipment;

third means for generating an availability list indicating available uplink time slots and downlink time slots having acceptable interference levels; and

a fourth means for allocating uplink and downlink timeslots using the availability list.

34. The system of claim 33 wherein the first means measures the interference level in each time slot at the base station and compares the measured level to a threshold to estimate unacceptable interference.

35. The system of claim 33 wherein the first means determines base station to base station (BS-BS) cross interfering cells with respect to the particular cell and estimates the unacceptable interference if any of the determined BS-BS interfering cells uses a slot for the downlink.

36. The system of claim 33 wherein the second means measures the interference level in each time slot by each user equipment and compares the measured level to a threshold to estimate unacceptable interference.

37. The system of claim 33 wherein the second means determines user equipment-user equipment (UE-UE) cross interfering cells with respect to the particular cell and estimates acceptable interference in a particular time slot if any of the determined UE-UE interfering cells uses the particular time slot for uplink.

38. A hybrid time division multiple access/code division multiple access communication system, the system comprising:

a particular cell site, comprising:

a base station and a plurality of user equipments;

a node B comprising a time slot allocation and release means for allocating uplink time slots and downlink time slots using an availability list; and

a radio network controller comprising a resource allocation device for: estimating time slots having unacceptable interference to the base station, estimating time slots having unacceptable interference to downlink communications associated with the user equipment, and generating the availability list indicating available uplink time slots and downlink time slots having acceptable interference levels.

39. The system of claim 38, further comprising a memory associated with said resource allocation device for storing said availability list.

40. The system of claim 38, wherein the node B further comprises: a slot controller for updating at least a portion of the availability list, and a memory for storing the at least a portion of the availability list.

41. The system of claim 40, wherein said at least a portion of an availability list is a complete version of said availability list.

42. The system of claim 40 wherein the at least a portion of the availability list is only information in the availability list that is relevant to the particular base station coverage area.