Multi-cell incremental redundancy

1. A method for transmitting a data block from a group of cells to a user equipment (UE), comprising:

receiving from the UE, by a primary cell, a neighboring cell measurement associated with a secondary cell;

selecting the secondary cell to join a transmit incremental redundancy (IR) group for the UE based on the neighboring cell measurement, wherein the transmit IR group includes the primary cell; and

transmitting first and second portions of the data block from the primary cell and the secondary cell respectively to the UE, wherein the first and second portions include different portions of the data block.

2. The method of claim 1 , wherein selecting the secondary cell to join the transmit IR group comprises:

comparing the neighboring cell measurement to a threshold; and

selecting the secondary cell to join the transmit IR group for the UE based on the neighboring cell measurement being above the threshold.

3. The method of claim 1 , wherein transmitting the first and second portions of the data block to the UE comprises transmitting simultaneously or substantially simultaneously the first and second portions of the data block from the primary cell and the secondary cell respectively to the UE.

4. The method of claim 3 , wherein transmitting the first and second portions of the data block to the UE further comprises transmitting the first and second portions of the data block, on a same carrier frequency and same physical resource blocks (PRBs), from the primary cell and the secondary cell respectively to the UE.

5. The method of claim 3 , wherein transmitting the first and second portions of the data block to the UE further comprises transmitting the first and second portions of the data block, on a same carrier frequency and different physical resource blocks (PRBs), from the primary cell and the secondary cell respectively to the UE.

6. The method of claim 3 , wherein transmitting the first and second portions of the data block to the UE further comprises transmitting the first and second portions of the data block, on different carrier frequencies, from the primary cell and the secondary cell respectively to the UE.

7. The method of claim 1 , wherein the first and second portions of the data block include overlapping and non-overlapping portions of the data block.

8. The method of claim 1 , further comprising:

signaling the created transmit IR group to the UE; and

signaling a first redundancy version (RV) index of the primary cell to the UE.

9. The method of claim 8 , further comprising:

signaling the first RV index of the primary cell to the secondary cell; and

computing, by the secondary cell, a second RV index of the secondary cell based on the first RV index.

10. The method of claim 9 , wherein computing the second RV index based on the first RV index comprises computing the second RV index using the formula:

rvidx (2, i )=modulus( rvidx (1, i )+2,4)

were rvidx (2, i) represents the second RV index and rvidx (1, i) represents the first RV index.

11. A method for processing transmissions from a group of cells to a user equipment (UE), comprising:

transmitting to a primary cell a neighboring cell measurement associated with a secondary cell;

receiving, by the UE, first and second transmissions from a transmit incremental redundancy (IR) group formed by the primary cell based on the cell measurement, wherein the first and second transmissions include respectively first and second portions of a data block, and wherein the first and second portions are selected respectively based on first and second redundancy version (RV) indices;

generating combined soft bits from the first and second transmissions based on the first and second RV indices; and

generating a bit sequence using the combined soft bits.

12. The method of claim 11 , wherein the transmit IR group includes the primary cell and the secondary cell associated with the UE, and wherein receiving the first and second transmissions includes receiving the first and second transmissions from the primary and secondary cells respectively.

13. The method of claim 12 , further comprising:

receiving from the primary cell an indication of the transmit IR group and the first RV index; and

determining the second RV index based on the first RV index.

14. The method of claim 13 , wherein determining the second RV index based on the first RV index comprises computing the second RV index using the formula:

rvidx (2, i )=modulus( rvidx (1, i )+2,4)

where rvidx (2, i) represents the second RV index and rvidx (1, i) represents the first RV index.

15. The method of claim 11 , wherein receiving the first and second transmissions comprises receiving simultaneously or substantially simultaneously the first and second transmissions by the UE.

16. The method of claim 11 , wherein the first and second portions correspond to different portions of the data block, and wherein the first and second transmissions are received simultaneously or substantially simultaneously by the UE on a same carrier frequency and same physical resource blocks (PRBs), and wherein generating the combined soft bits comprises:

determining for a bit in the first portion whether or not the bit is redundant in the second portion; and

generating a log likelihood ratio (LLR) value for the bit responsive to the determination.

17. The method of claim 16 , wherein determining whether or not the bit is redundant in the second portion comprises:

determining whether or not the bit is punctured in the second portion.

18. The method of claim 11 , wherein generating the combined soft bits comprises:

generating first soft bits and second soft bits from the first and second transmissions; and

combining the first soft bits and the second soft bits based on the first and second RV indices to generate the combined soft bits,

wherein the first and second portions correspond to a same portion of the data block, wherein the first and second transmissions are received by the UE on a same carrier frequency and different physical resource blocks (PRBs), or wherein the first and second transmissions are received by the UE on different carrier frequencies.

19. The method of claim 18 , wherein the first and second portions overlap in at least an overlapping portion of the data block, and wherein combining the first soft bits and the second soft bits comprises:

adding, soft bit by soft bit, a first group of the first soft bits with a corresponding second group of the second soft bits, wherein the first group of the first soft bits and the second group of the second soft bits each corresponds to the overlapping portion of the data block.

20. A user equipment (UE), comprising:

a transmitter configured to transmit a neighboring cell measurement associated with a secondary cell to a primary cell;

first and second receive antennas configured to receive first and second transmissions from a transmit incremental redundancy (IR) group formed by the primary cell based on the neighboring cell measurement, wherein the first and second transmissions include respectively first and second portions of a data block, and wherein the first and second portions are selected respectively based on first and second redundancy version (RV) indices;

a soft-output demapper configured to generate combined soft bits from the first and second transmissions based on the first and second RV indices; and

a decoder configured to generate a bit sequence using the combined soft bits.

21. The UE of claim 20 , wherein the first and second portions correspond to different portions of the data block, wherein the first and second receive antennas are further configured to receive the first and second transmissions simultaneously or substantially simultaneously on a same carrier frequency and same physical resource blocks (PRBs), and wherein the soft-output demapper is further configured to:

determine for a bit in the first portion whether or not the bit is redundant in the second portion; and

generate a log likelihood ratio (LLR) value for the bit responsive to the determination.

22. The UE of claim 21 , wherein the soft-output demapper is further configured to determine whether or not the bit is punctured in the second portion.

23. The UE of claim 20 , further comprising:

at least a third receive antenna configured to receive a third transmission from the transmit IR group, wherein the transmit IR group includes at least the primary cell and the secondary cell.

24. A method for transmitting a data block from a group of cells to a user equipment (UE), comprising:

receiving from the UE, by a primary cell, a plurality of neighboring cell measurements associated with a plurality of secondary cells;

selecting a secondary cell from the plurality of secondary cells to join a transmit incremental redundancy (IR) group for the UE based on the plurality of neighboring cell measurements, wherein the transmit IR group includes the primary cell; and

transmitting a same portion of the data block from the primary cell and the secondary cell respectively to the UE, wherein the same portion of the data block is transmitted on a same carrier frequency and different physical resource blocks (PRBs) or on different carrier frequencies from the primary and secondary cells respectively to the UE.