Method, apparatus and computer program to map a cyclic shift to a channel index

1. A method comprising:

receiving an uplink resource allocation that grants an uplink resource to a plurality of user equipments, and an indication in the uplink resource allocation of a cyclic shift;

sending data on the granted uplink resource;

mapping the granted uplink resource to a downlink resource in dependence on the indicated cyclic shift,

wherein the mapping is such that for a predetermined number of user equipments being allocated a same uplink resource in a single multi-user multiple input multiple output uplink resource allocation, each ones of said predetermined number of user equipments which map to an adjacent downlink resource exhibit an optimized cyclic shift relative to one another, and

wherein the cyclic shift is for a demodulation reference signal and the indication of the cyclic shift is a dynamic cyclic shift indicator of three bits that indicates a relative cyclic shift in a cell in which the plurality of user equipments operate; and

tuning a receiver to receive on the mapped downlink resource an indication about the sent data.

2. The method according to claim 1 , where the predetermined number of user equipments for which the relative cyclic shift is optimized comprises at least one of: two user equipments; three user equipments; or four user equipments.

3. The method according to claim 1 , wherein:

the downlink resource comprises a physical hybrid-automatic repeat request indicator channel and mapping the granted uplink resource to the downlink resource in dependence on the indicated cyclic shift comprises mapping the granted uplink resource to an index of the indicator channel that is offset according to the indicated cyclic shift which is a demodulation reference signal cyclic shift index;

the mapping is according to a linear mapping rule stored in a local memory of a user equipment executing the method; and

the indication about the sent data is one of an acknowledgement and a negative acknowledgement.

4. The method according to claim 3 , wherein a resource space for the mapped indicator channel is smaller than a signaling space for the indication of the cyclic shift.

5. A computer program product embodied on a non-transitory computer-readable medium storing a program of computer readable instructions that, when executed by a computer, is configured to provide instructions to control or carry out:

sending an uplink resource allocation that grants an uplink resource to a plurality of user equipments, and an indication in the uplink resource allocation of a cyclic shift for each of the plurality of user equipments;

mapping the granted uplink resource to a downlink resource in dependence on the indicated cyclic shift for each of the plurality of user equipments,

wherein the mapping is such that for a predetermined number of user equipments being allocated a same uplink resource in a single multi-user multiple input multiple output uplink resource allocation, each pair of said predetermined number of user equipments which map to an adjacent downlink resource exhibit an optimized cyclic shift relative to one another, and

wherein the cyclic shift for respective ones of the plurality of user equipments is a demodulation reference signal cyclic shift for respective ones of the plurality of user equipments and the indication of the cyclic shift is a dynamic cyclic shift indicator of three bits that indicates a relative cyclic shift in a cell; and

sending to each of the respective plurality of user equipments on the respective mapped downlink resource an indication about data received.

6. A computer program product embodied on a non-transitory computer-readable medium storing a program of computer readable instructions that, when executed by a computer, is configured to provide instructions to control or carry out:

receiving an uplink resource allocation that grants an uplink resource to a plurality of user equipments, and an indication in the uplink resource allocation of a cyclic shift;

sending data on the granted uplink resource;

mapping the granted uplink resource to a downlink resource in dependence on the indicated cyclic shift,

wherein the mapping is such that for a predetermined number of user equipments being allocated a same uplink resource in a single multi-user multiple input multiple output uplink resource allocation, each ones of said predetermined number of user equipments which map to an adjacent downlink resource exhibit an optimized cyclic shift relative to one another, and

wherein the cyclic shift is for a demodulation reference signal and the indication of the cyclic shift is a dynamic cyclic shift indicator of three bits that indicates a relative cyclic shift in a cell in which the plurality of user equipments operate; and

tuning a receiver to receive on the mapped downlink resource an indication about the sent data.

7. An apparatus comprising:

a receiver configured to receive an uplink resource allocation that grants an uplink resource to a plurality of user equipments, and an indication in the uplink resource allocation of a cyclic shift;

a transmitter configured to send data on the granted uplink resource;

a memory storing a mapping rule which maps a granted uplink resource to a downlink resource in dependence on a cyclic shift such that for a predetermined number of user equipments being allocated a same uplink resource in a single multi-user multiple input multiple output uplink resource allocation, each ones of said predetermined number of user equipments which map to an adjacent downlink resource exhibit an optimized cyclic shift relative to one another; and

a processor configured to map the granted uplink resource to a downlink resource in dependence on the indicated cyclic shift according to the mapping rule stored in the memory,

wherein the cyclic shift is for a demodulation reference signal and the indication of the cyclic shift is a dynamic cyclic shift indicator of three bits that indicates a relative cyclic shift in a cell in which the plurality of user equipments operate, and

wherein the receiver is further configured to receive on the mapped downlink resource an indication about the sent data.

8. The apparatus according to claim 7 , where the predetermined number of user equipments for which the relative cyclic shift is optimized comprises at least one of: two user equipments; three user equipments; or four user equipments.

9. The apparatus according to claim 7 , wherein:

the downlink resource comprises a physical hybrid-automatic repeat request indicator channel and mapping the granted uplink resource to the downlink resource in dependence on the indicated cyclic shift comprises mapping the granted uplink resource to an index of the indicator channel that is offset according to the indicated cyclic shift which is a demodulation reference signal cyclic shift index;

the mapping is according to a linear mapping rule stored in a local memory of a user equipment executing the method; and

the indication about the sent data is one of an acknowledgement and a negative acknowledgement.

10. A method comprising:

sending an uplink resource allocation that grants an uplink resource to a plurality of user equipments, and an indication in the uplink resource allocation of a cyclic shift for each of the plurality of user equipments;

mapping the granted uplink resource to a downlink resource in dependence on the indicated cyclic shift for each of the plurality of user equipments,

wherein the mapping is such that for a predetermined number of user equipments being allocated a same uplink resource in a single multi-user multiple input multiple output uplink resource allocation, each pair of said predetermined number of user equipments which map to an adjacent downlink resource exhibit an optimized cyclic shift relative to one another, and

wherein the cyclic shift for respective ones of the plurality of user equipments is a demodulation reference signal cyclic shift for respective ones of the plurality of user equipments and the indication of the cyclic shift is a dynamic cyclic shift indicator of three bits that indicates a relative cyclic shift in a cell; and

sending to each of the respective plurality of user equipments on the respective mapped downlink resource an indication about data received.

11. The method according to claim 10 , wherein:

the downlink resource comprises a physical hybrid-automatic repeat request indicator channel and mapping the granted uplink resource to the downlink resource in dependence on the indicated cyclic shift for each of the plurality of user equipments comprises mapping for each of the plurality of user equipments the granted uplink resource to an index of the indicator channel that is offset according to the indicated cyclic, shift for a respective one of the plurality of user equipments which is a demodulation reference signal cyclic shift index for the respective user equipment;

the mapping is according to a linear mapping rule stored in a local memory of an access node executing the method; and

the indication about the data received on the respective mapped downlink resource is one of an acknowledgement and a negative acknowledgement.

12. The method according to claim 10 , wherein the predetermined number of user equipments for which the relative cyclic shift is optimized comprises at least one of: two user equipments; three user equipments; or four user equipments.

13. The method according to claim 10 , further comprising monitoring the uplink resource that was granted to each of the plurality of user equipments for data from the respective user equipments.

14. The method according to claim 11 , wherein a resource space for the mapped indicator channel for the plurality of user equipments is smaller than a signaling space for the indication of the cyclic shift for the plurality of user equipments.

15. An apparatus comprising:

a transmitter configured to send an uplink resource allocation that grants an uplink resource to a plurality of user equipments, and an indication in the uplink resource allocation of a cyclic shift for each of the plurality of user equipments;

a memory storing a mapping of an uplink resource to a downlink resource in dependence on a cyclic shift for each of the plurality of cyclic shifts,

wherein the mapping is such that for a predetermined number of user equipments being allocated a same uplink resource and a different cyclic shift in a single multi-user multiple input multiple output uplink resource allocation, each pair of mapped adjacent downlink resource exhibit an optimized cyclic shift relative to one another, and

wherein the cyclic shift for respective ones of the plurality of user equipments is a demodulation reference signal cyclic shift for respective ones of the plurality of user equipments and the indication of the cyclic shift is a dynamic cyclic shift indicator of three bits that indicates a relative cyclic shift in a cell;

a processor configured to map the granted uplink resource to a downlink resource in dependence on the indicated cyclic shift for each of the plurality of user equipments according to the mapping stored in the memory; and

the transmitter further configured to send to each of the respective plurality of user equipments on the respective mapped downlink resource an indication about data received.

16. The apparatus according to claim 15 , further comprising a receiver configured to monitor the uplink resource that was granted to each of the plurality of user equipments for data from the respective user equipments.

17. The apparatus according to claim 15 , wherein:

the downlink resource comprises a physical hybrid-automatic repeat request indicator channel and mapping the granted uplink resource to the downlink resource in dependence on the indicated cyclic shift for each of the plurality of user equipments comprises mapping for each of the plurality of user equipments the granted uplink resource to an index of the indicator channel that is offset according to the indicated cyclic shift for a respective one of the plurality of user equipments which is a demodulation reference signal cyclic shift index for the respective user equipment;

the mapping is according to a linear mapping rule stored in the memory; and

the indication about the data received on the respective mapped downlink resource is one of an acknowledgement and a negative acknowledgement.

18. The apparatus according to claim 15 , wherein the predetermined number of user equipments for which the relative cyclic shift is optimized comprises at least one of: two user equipments; three user equipments; or four user equipments.