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

The present invention relates in general to the allocation of resources in wireless arrangements of multiple access communication by hybrid time division / multiple access by code division. More specifically, the invention relates to the allocation of uplink and downlink time slots in said arrangements.

Figure 1 illustrates a wireless communication arrangement. The arrangement has a plurality of base stations 30₁-30₁₁. Each base station 30_x communicates with user equipment (UEs) 32_lf 32₃, 32₄ in your area or operating cell. Communications transmitted from base station 30i to the EU 32₃ known as downlink communications and communications transmitted from the EU 32_xto base station 30_x They are known as uplink communications.

In addition to communicating about different frequency spectra, the multiple access provisions by division of various spectrum code (CDMA) carry multiple communications on the same spectrum. Multiple signals are distinguished by their respective chip codes (codes). To more effectively use the diverse spectrum, some hybrid time division (TDMA) / CDMA multiple access arrangements as illustrated in Figure 2 use repetitive frames 34 divided into a number of slots

<img file="AR040358A2_D0001.tif" />

of time 36j-36_n, like being fifteen. In time division duplex (TDD) arrangements that use CDMA, a time slot is used only for communication. cations of downlink or uplink in a cell. In these arrangements, a communication is sent in selected time slots 36_x-36_n using selected codes. According to Elio, a frame 34 is capable of transporting multiple communications distinguished by both time slot 36j-36_n as per code. The use of a single code in a single time slot with a dispersion factor of sixteen is known as a resource unit. Based on the bandwidth requirements of a communication, one or multiple resource units can be assigned to a communication.

A problem in such arrangements is cross cell interference as illustrated in Figure 3. A second cell base station 30₂ sends a downlink communication 40 to the UE 32₂ of a second cell in a certain time slot. In the same ran ura time, an uplink communication 38 is sent from the UE 32_x of a first cell. The uplink communication 38 may be received by the base station of the first cell 30j at an unacceptable interference level. While the base station of the second cell 30₂ is further than the UE of the first cell 32 !, the greatest radiated power

<img file="AR040358A2_D0002.tif" />

isotopically effective (EIPR) of the second cell base station 30₂ an unacceptable interference may result in the base station of the first cell 3 (^.

Also shown in Figure 3 is cross interference between UEs 32_lz 32₂. An uplink serial 38 of a UE 32₃ from the first cell will create unacceptable levels of interference to a downlink communication 40 in the same time slot received by the UE 32₂ of the second cell due to Its close proximity.

According to him, there is a need to reduce cross-interference of cells.

A particular cell of a multiple access communication arrangement by hybrid time division / multiple access by code division has a base station and a plurality of user equipment. Time slots that have unacceptable interference to the uplink are estimated. Time slots are estimated that have unacceptable interference to the downlink. An availability list is produced. The availability list indicates available uplink and downlink time slots with acceptable interference levels. Time slots with uplinks and downlinks are assigned using the availability list.

Figure 1 is a CDMA arrangement of various wireless spectrum.

<img file="AR040358A2_D0003.tif" />

Figure 2 illustrates time slots in boxes repeated

Figure 3 illustrates cross cell interference.

Figure 4 is an availability list.

Figure 5 is a flow chart for generating an availability list using base station to base station (BS-BS) and user equipment î user equipment (EU-EU) interference cells.

Figure 6 is an example of a list of cross-interference cells.

Figure 7 is a table showing a hypothetical time slot allocation for each cell.

Figure 8 is an availability list for cell 1 constructed using Figures 6 and 7.

Figure 9 is a flow chart for producing an availability list using BS-BS interference cells only.

Figure 10 is an illustration of a BS-BS cross interference list.

Figure 11 is a flow chart for producing an availability list using i cells EU-EU interference only.

Figure 12 is a cross interference list

EU-EU.

Figures 13 and 14 are flow charts that use the

<img file="AR040358A2_D0004.tif" />

Measurement of base station and user interference to determine the availability of time slots.

Figure 15 is an illustration of a specific availability list for user equipment.

Figures 16 and 17 are flow charts for using only interference measurements to determine the availability of time slots.

Figures 18, 19 and 20 are flow charts to determine the availability of time slots using hybrid approaches.

Figure 21 is a flow chart of a time slot allocation approach.

Figure 22 is a flow chart of availability list update.

Figure 23 is the updated table of Figure 7.

Figure 24 is an updated availability list for cell 7 based on Figure 23.

Figure 25 is an embodiment of centralized architecture.

Figure 26 is an embodiment of decentralized architecture.

While the allocation of time slots in the context of a TDD / CDMA arrangement is described below, the same time slot removal procedures

<img file="AR040358A2_D0005.tif" />

and availability lists can be applied to a hybrid TDMA / CDMA arrangement where uplink and downlink communications occur in the same time slot in a cell.

Figure 4 illustrates a time slot availability list 76. Along the horizontal axis, each time slot is expressed as SI, S2, ..., SN. Along the vertical axis, each cell, expressed here by the sub-index of its associated base station reference number, is expressed for the uplink and the e nlace descending. Each row indicates the time slot availability for the uplink or downlink of a cell. The unavailable time slots are indicated by an X. The available time slots are left empty.

A procedure for generating the availability list is shown in Figure 5 and is explained in conjunction with Figures 6, 7 and 8. Initially, cross interference between each pair of cells is measured. Initially the base station interference cells 30 are determined₁-30₁₁ to base station 3 (^ - 3 (^ (BS-BS), step 77. Interference cells BS-BS are cells in which the transmissions of base stations 3 (^ - 3 (^ interfere with the reception of other stations base 30₁-30₁₁.

Each cell determines its BS-BS interference cells by estimating the interference of other cells. An esteemed approach

<img file="AR040358A2_D0006.tif" />

The BS-BS interference cells using pre-edited gains between the base stations e 30_x—30- If the estimated interference exceeds a threshold, the cells of the base stations are considered BS-BS interference cells, then 77. On the basis of the threshold comparison, the BS-BS interference cells are terminated and stored n the list of cross-interference cells 84 as illustrated in Figure 6.

The vertical axis of the list of routed interference cells 84 has each cell. The horizontal axis has cells and potential cross interference. A cell that has [BS-BS interference with respect to another cell is marked in the [appropriate box by means of an I, step 79. For example, since the communications in cell 2 produce a cross interference with cell 1, the box from the first row, second column is marked with an I. Since a cell does not interfere with itself, these lockers are marked with an X.

In addition, the cells in which the UEs 32! -32 are determined_n may interfere with other UEs 32 ^ 32 ,,, step 78. Due to the relatively low EIPR of UEs 32_x-32_n EU-EU interference cells are in close geographical proximity, for example adjacent. An uplink transmission of UEs 32₂ may interfere with the reception of the UE from a neighboring cell, as shown in Figure 3. Due to

<img file="AR040358A2_D0007.tif" />

that geographically close cells can have UEs 52! -32_n which can interfere with each other, these cells are also classified as interference cells. In Figure 6, EU-EU interference cells that were not BS-BS Interference cells are marked with an I *, step 79.

Using the list of cross interference cells 84, each cell determines the potential cross interference cells, step 78. For a particular cell on its vertical axis, each cell in the corresponding row narrates It gives an I ο I * is a zruzada interference cell. For example, cell 1 potentially receives cross interference from cells 2, 3, 5, 6, 9 and 10. For each cross interference cell, the time slot allocation is determined. For example, using the hypothetical time slot assignment in Table 86 of Figure 7, cell 2 is assigned downlink time slots 1 and 2 and uplink time slot 9. For each slot of downlink time allocated in a cross interference cell, a corresponding uplink time slot is eliminated, step 80. To illustrate using Figure 6, 7 and 8, for cell 1, cell 2 to which the downlink time slot 1 is assigned, the available uplink time slots of cell 1 are deleted, as shown with an X in the availability list 88 in cell 1 of a Figure 8.

For each link time slot to

<img file="AR040358A2_D0008.tif" />

On a cross interference cell, a corresponding downlink time slot is removed, step 82. In order to illustrate cell 1, the uplink time slot 9 of cell 2 removes that time slot from the time heals of Possible downlink from cell L, as shown in availability list 88 of cell 1. After removing the appropriate time slots due to the cross interference cells, an Availability List 7 6 is produced for each cell, step 90. As a result, the uplink and downlink time slots used in cross interference cells they become unavailable, reducing cross cell interference.

To lighten the allocation conditions, only BS-BS interference cells or only EU-EU interference cells are considered. These approaches can achieve the release of more resources for each cell. However, the criteria Less strict may result in unacceptable levels of interference for some users.

Figure 9 is a flow chart for producing an availability list using only BS-BS interference cells. The BS-BS interference cells are identified, step 122. A cross-interference list BS-BS 132 is produced,

-r *

<img file="AR040358A2_D0009.tif" />

as shown in Figure 10. If a cell uses a time slot for the uplink, that slot is removed for use by BS-BS interference cells for the downlink, step 126. On the contrary, if a cell uses a time slot for the downlink, that slot is removed for use by BS-BS interference cells for the uplink, step 128. A list of available time slots is produced for each cell, step 130. While this approach uses the resources of the provision more aggressively, some users may suffer interference Unacceptable downlink links.

Figure 11 is a flow chart for producing an availability list using only EU-EU interference cells. The EU-EU interference cells are identified, step 134. An EU-EU cross interference list 142 is produced, as in Figure 12. If a cell uses a time slot for the uplink, that slot is removed to be used by EU-EU interference cells for the downlink, step 136. On the contrary, if a cell uses a time slot for the uplink, that slot is removed for use by EU-EU interference cells for the uplink, step 138. A list of available time slots is produced for each cell, step 140. This approach can result in levels of link interference

<img file="AR040358A2_D0010.tif" />

ascending unacceptable to some users.

Another approach to determine available time slots uses in measurements time slot interference, such as through serial interference code (ISCP) power. Interference measurements can be taken at base stations 30₃-30_n, EU 32₃-32_n or both.

Figure 13 is a flow chart using base station measurements and interference UE to determine available time slots for each UE 32 ^ 32 ^ For a particular cell, the level of interference in each time slot is measured at the station base 30₃, step 144. Each of the cells of the UEs 32_lz 32₃-32₄ also measure the interference levels in each time slot, step 14 6. The measurements of time slot interference by the base stations are used to determine the availability of uplink time slots. The availability of downlink time slot is determined on an EU-by-EU basis (EU-specific basis) .

For the uplink, if the measured interference of the base station exceeds a threshold in a time slot, that time slot is eliminated for the uplink, step 148. For the downlink, each UE 32i, 32₃, 32₄ eliminates downlink time slots for use, if the interference measure of that UE exceeds a threshold,

<img file="AR040358A2_D0011.tif" />

step 150. An availability list 154 is produced which lists the available uplink time slots and the cisponible downlink time slots for each UE as illustrated in Figure 15, step 152.

While two cells are adjacent, the location of UEs 32_x-32_n In cells it can be distant. To illustrate using Figure 1, cell 1 and cell 2 are adjacent. However, a UE 32₄ is distant from cell 2. According to elio, if the UE 32₂ in cell 2 use a canur a for the uplink, most likely it will not interfere with the downlink reception of the UE 32₄. However, the upstream transmissions of the UE 32₂they would probably interfere with the transmission of UE 32_x of &lt;&gt; descending link. As a result, a more aggressive resource allocation is available using a specific availability list for UE 154. A disadvantage is the greater signaling required. Due to the mobility of the UE and other cell reallocations, the Interference measurements must be updated and signaled to the 30X-3ÛH base station frequently.

Figure 14 is a flow chart using measurements of the base station and UE interference to determine available time slots not specific to UE. The base roasting 30i measures the interference in each slot of

<img file="AR040358A2_D0012.tif" />

iempo, step 144, and so does each EU 32₂, 3 'iaso 14 6. For him in uplink, if the interference from the base station exceeds a threshold in a time slot, that time slot is removed, step 148. For the downlink, if any interference measured from the UEs of that cell in a time slot exceeds the threshold, that time slot is removed for the downlink, step L56. Using the deleted time slots, an Availability List 88 is produced for each cell, for example as in Figure 8. Because the UE measurements are effectively zombied, the missing EU interference measurements are not critical for the allocation of resource unit

Figures 16 and 17 are flow charts using only EU interference measurements to determine available time slots. In one cell, each UE measures the interference in each time slot, step 160. For the uplink, if some measure of EU interference exceeds the threshold, that time slot is eliminated for the link ce ascending, step 160. Alternatively, to reduce the amount of uplink time slots removed, only the time slots in which most UEs have unacceptable interference are removed from the uplink, step 160. If only a few UEs have unacceptable interference, these UEs are supposed to

<img file="AR040358A2_D0013.tif" />

They are in the margin of the cell and are not represented by the global conditions of the cell.

Using a specific allocation approach for UE as in Figure 16, each UE 32₃, 32₃, 32₄, has its own set of available downlink time slots, as shown in Figure 15. For example, one downlink time slot is deleted for each flE 32_lf 32₃, 32₄, if the interference measurement of that UE in the time slot exceeds a threshold, step 164. A specific availability list 150 for UE is produced, step 166.

In Figure 1 7 a non-specific approach to JE is shown. If the measurement of interference from the UE or the layout of the UEs exceeds a threshold in the time slot, this time slot is deleted for the downlink,) then 168. An availability list 88 is produced, as on Thursday It is shown in Figure 8, for the entire cell.

Figures 18, 19 and 20 are approaches for determining the availability of time slots, using hybrid BS-BS interference, EU-EU interference interference approaches. Figures 18 and 19 are measurements of cells Je BS-BS interference and EU interference. The interference eldas BS-BS, step 172 are determined. Each UE 32_lf 32₃, |32₄, measure the interference in each time slot, step 174. For the uplink, the time slots are eliminated, if a BS-BS interference cell uses it for the

<img file="AR040358A2_D0014.tif" />

gnlace descending step 176.

Downlink availability is determined ina on an EU basis by EU or collective basis. Using one EU base per EU as in Figure 18, each EU 32_lz 32₃, 32₄ Compare each measurement of time slot interference with a threshold. Ç When a time slot measurement exceeds the threshold, the time anura is eliminated for that UE 32_x, 32₃, 32₄, in the downlink, step 178. A list of specific availability for UE 150 is produced, as in Figure L5, step 180.

Using a collective base as shown in Figure 19, if any measurement of time slot interference UE exceeds a threshold, that time slot is removed for the downlink to the cell, step 182. An availability list is produced 88 , as shown in Figure 8, step 184.

Figure 20 uses EU-EU interference cells and base station interference measurements. A cell base station 30i measures the interference levels in each time slot, step 18 6. The EU-EU interference cells are identified, step 188. For the uplink, the uplink time slots are eliminated, if the interference for that time slot exceeds a threshold, step 190. For the downlink, a downlink time slot is removed, if a cell of

<img file="AR040358A2_D0015.tif" />

EU-EU interference uses it for uplink,

I92. Based on the deleted time slots, an availability list 88 is produced, as in Figure 8.

For sectorized cells, the interference list: routed and the availability lists 84 are constructed for the sector within the cells. The cross interference between all sectors of the cell is determined. Although the following analysis deals with non-sectorized cells, the same approach is applied to sectorized cells where the assignment is made on a sector-based basis rather than per cell.

Using the availability list dad 76, each station&gt; ase 30j-30_n receives the allocation of time slots to support its communications using the procedure of the ^?Figure 21. Initially an order is placed for a slot ie additional time or more, step 92. Referring to the availability list 76 of that station, it assigns available time slots. To illustrate using the availability list 88 of Figure 8, the base station 30χ requires both an additional assigned downlink and an uplink time slot. The available uplink time slots are slots 4 and 7-16 and the available downlink time slots are slots 1-3, 5, 6, 8, 10-13 and 16. A time slot will be assigned of link

<img file="AR040358A2_D0016.tif" />

uplink and a downlink time slot between the corresponding available downlink and uplink time slots. Whether employs an availability list 150 specific to UE, the 'downlink' assignment is based on UE 32! ~ 32_n which requires the downlink resource unit (s).

Since base stations 30χ-30_η they need to allocate f dynamically release time slots due to the uplink / downlink variable demand, the information in the availability list 76 requires updating. In the case of approaches that use interference measurements, updates are carried out by updating the measurements and lists.

For BS-BS and EU-EU approaches, this procedure is shown in Figure 22. Initially, cross interference cells are identified by each assigned or released time slot, step 96. For each assigned downlink time slot, the corresponding time slots in the interference cells crosses da are removed for the uplink, step 98. On the contrary, if the uplink time slot is assigned, the corresponding time slots in the cross interference cells for the downlink are eliminated, step 100. To illustrate with Figures 23 and 24, the base station 30₆ associated with cell 6 allocates the slot

<img file="AR040358A2_D0017.tif" />

ce time 7 for the downlink D *, and rc time 8 for the uplink, U *, as indicated in Table 106 of Figure 23. The cross interference cells are cells 1, 2, 5 and 7 As shown in the availability list 107 for cell 7 of Figure 24, the time slot 7 is removed for the uplink and the time slot 8 is deleted for the downlink, both marked as X *.

When a downlink time slot has been released, the corresponding time slots in the cross interference cells are released for the link to scenario, unless not available for other reasons, for example used as a downlink time slot in another cross interference cell, step 102. For example, if the time slot 6 of cell 6 is released; as indicated in table 106 as D **, the uplink time slot 6 of cell 1 is not set. Cell 9 is a cross interference cell to cell 1, which also uses the downlink time slot 6. On the contrary, for cell 7, the release of the downlink time slot 6 releases the cell for uplink communications as shown in the availability list 108 for cell 7, with R. If a uplink time slot, the corresponding time slots in the

<img file="AR040358A2_D0018.tif" />

Cross interference cells are released for the downlink unless they are not available for other reasons, step 104.

A focus To use the uplink / downlink time slot assignment shown in Figure 25 using a centralized architecture. The radio network controller (RNC) 110 has a resource allocation device 11 for allocating or releasing a time slot based on user demand. If you are assigning, resource allocation device 116 in ANC 110 assigns an appropriate time slot using the availability list 76, stored in its memory 117, in accordance with the procedure in Figure 21. Time slots and codes Selected channel channels are communicated to the 2Stat base 30i-30_N and to the EU 3O₂.-3O_N through the allocation of time slot node B and Release device 112 ^ 112 ,,. If you are releasing a time slot, the resource allocation device RNC 116 releases the time slot and updates the availability list 76. Agree with this, the update of the availability list 76 is centralized as it takes place in the RNC 110.

Another approach to the uplink / downlink time slot assignment is shown in Figure 3Ö using a decentralized architecture. Each node B

<img file="AR040358A2_D0019.tif" />

u] 22! -122_n has its own tïëfiTpo slot controller] 20i ~ 120_n. When a time slot 112 ^ 112 ,, assignment and release device requests time slots for a communication, the time slot controller of node B 120J-120 ,, selects an appropriate time slot from:&gt; or list of availability 76, such as is stored in its memory 121ι · The list of stored availability 76, to seduce its capacity, can only contain the celestial grooves for the cell or cells of that node B. On the contrary, the stored availability list 76 may contain the availability of all c eldas of the RNC. The decentralized approach allows for faster performance.

The selected time slot is assigned to the communication by means of the device for assigning and releasing time slots 112₁-112_n. In order to update lists 76, said node B 122 ^ 122 ,, updates its list 7 6. The assigned and released time slots are also sent to the RNC 110. The RNC 110 directs the appropriate time slot update information to the other cells. The information on time slots contains an updated availability list 76 or merely changes in list 76. If only changes are sent, the controller in each cell 12 (^ - 120 ,, updates its own availability list 76 with that information. The type of time slot information sent is based on the requirements of

<img file="AR040358A2_D0020.tif" />

uplink / downlink is adaptable to arrangements that support different signaling speeds. For For provisions that only support slow network signaling, the assigned time slot information is updated daily using a statistical analysis of the uplink / downlink demand. Because communication traffic varies during the day, a faster refresh rate operates better and is preferred. In the case of medium speed network signaling, the update is carried out periodically oscillating between a fraction of an hour and several hours. Medium speed network signaling also uses statistical analysis but in less time. In the case of fast network signaling, the assigned time slots are updated by call or by frame. Once a time slot is assigned or released, the appropriate lists are updated. Fast network signaling allocates time slots as needed. As a result, it uses the resources of the provision more effectively. &lt; XX112146514&gt;