WIRELESS COMMUNICATION METHOD AND APPARATUS FOR ASSIGNING CELL AND RESOURCE BLOCKS

• US 20080068981A1
• Filed: 09/11/2007
• Published: 03/20/2008
• Est. Priority Date: 09/14/2006
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Marinier, Paul
• Granted Patent: US 8,095,139 B2
• Time in Patent Office: Days
• US Class Current: 370/208
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04B 17/345 Interference values signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] H04B17/336
• CPC Class Codes: H04B 17/382 for resource allocation, admission control or handover
• CPC Class Codes: H04W 36/20 for optimising the interference level
• CPC Class Codes: H04W 52/343 taking into account loading or congestion level
• CPC Class Codes: H04W 52/50 at the moment of starting communication in a multiple access environment
• CPC Class Codes: H04W 72/541 using the level of interference

Abstract

A method and apparatus for assigning cell and resource blocks to a wireless transmit/receive units (WTRU) in a wireless communication system including a resource management unit and a plurality of cells having resource blocks are disclosed. The WTRU is currently associated with a particular one of the cells. Path losses between the WTRU and cells neighboring the particular cell are determined. The average level of inter-cell interference on each resource block at each cell neighboring the particular cell is then determined. A signal-to-interference ratio (SIR) is then determined to support a guaranteed bit rate of the WTRU on an uplink.

Claims

1. A method of assigning cell and resource blocks to a wireless transmit/receive unit (WTRU) in a wireless communication system including a resource management unit and a plurality of cells having resource blocks, the WTRU being currently associated with a particular one of the cells, the method comprising:

(a) determining path losses between the WTRU and cells neighboring the particular cell;

(b) determining the average level of inter-cell interference generated by the WTRU at each neighboring cell and resource block; and

(c) determining a signal-to-interference ratio (SIR) required to support a guaranteed bit rate of the WTRU on an uplink.

2. The method of claim 1 wherein step (a) further comprises:

the WTRU measuring the received signal strength of a certain beacon signal transmitted by each of the cells at a known transmission power on a known resource block; and

the WTRU reporting the received signal strength to the resource management unit.

3. The method of claim 2 wherein the WTRU reports an average received signal strength to the resource management unit.

4. The method of claim 1 wherein step (a) further comprises:

the WTRU transmitting a probe signal on a certain reserved resource block at a specified transmission power.

5. The method of claim 4 wherein step (a) further comprises:

the WTRU receiving measurements of the received signal strength of the probe signal.

6. The method of claim 1 wherein step (b) further comprises:

measuring the average level of inter-cell interference by candidate cells on each resource block.

7. The method of claim 6 wherein the measurement of the average level of inter-cell interference is performed upon request.

8. The method of claim 6 wherein the measurement of the average level of inter-cell interference is performed on a periodic basis.

9. The method of claim 1 wherein step (c) further comprises:

determining, based on the SIR, whether a maximum transmission power of the WTRU would be exceeded, or if a maximum level of inter-cell interference on a candidate cell/resource block would be exceeded.

10. The method of claim 1 further comprising:

the resource management unit determining an expected increase of inter-cell interference on resource blocks at neighboring cells for each candidate assignment.

11. The method of claim 10 further comprising:

estimating the required transmission power (TxPower) of the WTRU based on the required SIR, the average level of inter-cell interference on the candidate cell and resource block, I_cand, and the path loss to the candidate cell, L_cand, based on the following formula;

TxPower(dBm)=SIR(dB)+L_cand(dB)+I_cand(dBm).

12. The method of claim 11 further comprising:

calculate the resulting level of inter-cell interference, Δ

I_i, generated by the WTRU at each neighboring cell, i, and resource block, j, based on the required transmission power and the path loss between the WTRU and the neighboring cell L_i;

Δ

I_i(dBm)=TxPower(dBm)−

L_i(dB).

13. The method of claim 12 further comprising:

estimating the relative increase of inter-cell interference, I_ij′

/I_ij, on each resource block at each cell based on the pre-existing level of inter-cell interference;

I_ij′

/I_ij(dB)=10 log 10[1+Δ

I_i(mW)/I_ij(mW)].

14. The method of claim 13 wherein after the resource management unit has estimated the set of estimated relative increases of inter-cell interference for each candidate cell and resource block assignment, an elected assignment is determined based on the smallest sum of estimated relative increases of inter-cell interference.

15. The method of claim 13 wherein after the resource management unit has estimated the set of estimated relative increases of inter-cell interference for each candidate cell and resource block assignment, an elected assignment is determined based on the smallest maximum among the estimated relative increases of inter-cell interference.

16. The method of claim 13 wherein after the resource management unit has estimated the set of estimated relative increases of inter-cell interference for each candidate cell and resource block assignment, an elected assignment is determined based on the smallest weighted sum of estimated relative increases of inter-cell interference.

17. A resource management unit for managing a plurality of cells and resource blocks, the resource management unit comprising:

(a) a receiver for receiving i) received signal strength measurements of a certain beacon cell transmitted by each of a plurality of cells at a known transmission power on a known resource block, and ii) inter-cell interference measurements performed by candidate cells on each resource block; and

(b) a processor for estimating a signal-to-interference ratio (SIR) required to support a guaranteed bit rate of the WTRU on an uplink.

18. The resource management unit of claim 17 wherein the WTRU reports an average received signal strength to the resource management unit.

19. The resource management unit of claim 17 wherein neighboring cells report measurements of the received signal strength to the resource management unit.

20. The resource management unit of claim 19 wherein the neighboring cells report an average received signal strength.

21. The resource management unit of claim 17 wherein the average level of inter-cell interference by the candidate cells on each resource block is measured.

22. The resource management unit of claim 21 wherein the measurement of the average level of inter-cell interference is performed upon request.

23. The resource management unit of claim 21 wherein the measurement of the average level of inter-cell interference is performed on a periodic basis.

24. The resource management unit of claim 17 wherein the processor determines whether the maximum transmission power of the WTRU would be exceeded, or if the maximum level of inter-cell interference on a candidate cell/resource block would be exceeded, based on the SIR estimate.

25. The resource management unit of claim 17 wherein the processor determines an expected increase of inter-cell interference on resource blocks at neighboring cells for each candidate assignment.

26. The resource management unit of claim 25 wherein the processor estimates the required transmission power (TxPower) of the WTRU based on the required SIR, the average level of inter-cell interference on the candidate cell and resource block, I_cand, and the path loss to the candidate cell, L_cand, based on the following formula:

TxPower(dBm)=SIR(dB)+L_cand(dB)+I_cand(dBm).

27. The resource management unit of claim 26 wherein the processor calculates the resulting level of inter-cell interference, Δ

I_i, generated by the WTRU at each neighboring cell, i, and resource block, j, based on the required transmission power and the path loss between the WTRU and the neighboring cell, L_i;

Δ

I_i (dBm)=TxPower (dBm)−

L_i (dB).

28. The resource management unit of claim 27 wherein the processor estimates the relative increase of inter-cell interference, I_ij′

/I_ij, on each resource block at each cell based on the pre-existing level of inter-cell interference;

I_ij′

/I_ij(dB)=10 log 10[1+Δ

I_i(mW)/I_ij(mW)].

29. The resource management unit of claim 28 wherein after the resource management unit has estimated the set of estimated relative increases of inter-cell interference for each candidate assignment, the assignment being determined based on the smallest sum of estimated relative increases of inter-cell interference.

30. The resource management unit of claim 29 wherein after the resource management unit has estimated the set of estimated relative increases of inter-cell interference for each candidate cell and resource block assignment, an elected assignment is determined based on the smallest maximum among the estimated relative increases of inter-cell interference.

31. The resource management unit of claim 29 wherein after the resource management unit has estimated the set of estimated relative increases of inter-cell interference for each candidate cell and resource block assignment, an elected assignment is determined based on the smallest weighted sum of estimated relative increases of inter-cell interference.

32. A wireless transmit/receive unit (WTRU) comprising:

(a) a receiver configured to receive information from a resource management unit about a particular cell and a resource block that the WTRU should use, path losses between the WTRU and cells that neighbor a cell that the WTRU operates within, and inter-cell interference levels of specified resource blocks at specified neighboring cells; and

(b) a processor for estimating a signal-to-interference ratio (SIR) required to support a guaranteed bit rate of the WTRU on an uplink.

33. The WTRU of claim 32 wherein the WTRU reports an average received signal strength to the resource management unit.

34. The WTRU of claim 32 further comprising:

(c) a transmitter configured to request interference levels of specified resource blocks at specified neighboring cells from a resource management unit.

35. The WTRU of claim 32 wherein the processor autonomously estimates the SIR needed to support the guaranteed bit rate.

36. The WTRU of claim 32 wherein the processor estimates the SIR needed to support the guaranteed bit rate based on the received information.

37. The WTRU of claim 32 wherein the received information further includes a maximum bit rate or a maximum transmission power that the WTRU should use to limit inter-cell interference that the WTRU generates.