Methods of Channel State Information Feedback and Transmission in Coordinated Multi-Point Wireless Communications System

1 . A method of operating an eNB in a wireless communication network, wherein the eNB is configured for coordinated multipoint (CoMP) transmission, the method comprising:

determining, by the eNB, whether to use a fall back transmission scheme for communicating with a UE in the network, wherein the fall back transmission scheme is different from a regular transmission scheme; and

transmitting, by the eNB, data using the fall back transmission scheme in one or more selected subframes and/or on selected frequency resources.

2 . The method of claim 1 , wherein the fallback transmission scheme is signalled by a different control signal from that of the regular transmission scheme transmitted from the eNB.

3 . The method of claim 1 , wherein the regular transmission scheme and the fall back transmission scheme have different control channel formats.

4 . The method of claim 1 , wherein the fall back transmission scheme uses single point transmission or transmit diversity.

5 . An eNB configured for coordinated multipoint (CoMP) transmission, the eNB comprising:

a processor configured such that the eNB determines whether to use a fall back transmission scheme for communicating with a UE, wherein the fall back transmission scheme is different from a regular transmission scheme, and wherein the processor is further configured such that the eNB transmits data using the fall back transmission scheme in one or more selected subframes and/or on selected frequency resources.

6 . The eNB of claim 5 , wherein the fallback transmission scheme is signalled by a different control signal from that of the regular transmission scheme transmitted from the eNB.

7 . The eNB of claim 5 , wherein the regular transmission scheme and the fall back transmission scheme have different control channel formats.

8 . The eNB of claim 5 , wherein the fall back transmission scheme uses single point transmission or transmit diversity.

9 . A method of operating a UE in a wireless communication network, the method comprising:

decoding, by the UE, information transmitted on a downlink control channel from an eNB in the network, wherein the eNB is configured for coordinated multipoint (CoMP) transmission; and

determining, by the UE, whether data channel is to be transmitted using a regular transmission scheme or a fall back transmission scheme.

10 . The method of claim 9 , wherein the regular transmission scheme and the fall back transmission scheme have different control channel formats.

11 . The method of claim 9 , wherein the fall back transmission scheme uses single point transmission or transmit diversity.

12 . The method of claim 11 , wherein the transmit diversity is per-TP transmit diversity or cross-TP transmit diversity.

13 . A UE comprising:

a processor configured such that the UE decodes information transmitted on a downlink control channel from an eNB in a wireless communication network, wherein the eNB is configured for coordinated multipoint (CoMP) transmission, and wherein the processor is further configured such that the UE determines whether a data channel is to be transmitted using a regular transmission scheme or a fall back transmission scheme.

14 . The UE of claim 13 , wherein the regular transmission scheme and the fall back transmission scheme have different control channel formats.

15 . The UE of claim 13 , wherein the fall back transmission scheme uses single point transmission or transmit diversity.

16 . The UE of claim 15 , wherein the transmit diversity is per-TP transmit diversity or cross-TP transmit diversity.

17 . A method of operating a UE in a wireless communication network, the method comprising:

receiving, by the UE, information on one or more sets of CSI-RS ports from one or more transmission points (TPs) in the network, wherein the TPs are configured for coordinated multipoint (CoMP) transmission;

measuring, by the UE, a channel on the one or more sets of CSI-RS ports; and

transmitting, by the UE, one or more feedback signals to one or more of the TPs, wherein the feedback signals contain one or more parameters indicative of the condition of the channel.

18 . The method of claim 17 , wherein the one or more parameters comprise channel state information CSI.

19 . The method of claim 17 , wherein each of the TPs is deployed in one or more of a homogeneous network or a heterogeneous network.

20 . The method of claim 17 , wherein receiving the information comprises receiving a set of one or more CSI-RS ports transmitted from one or more TPs.

21 . A UE comprising:

a processor configured such that the UE receives information on one or more sets of CSI-RS ports from one or more transmission points (TPs) in a wireless communication network, wherein the TPs are configured for coordinated multipoint (CoMP) transmission, and wherein the processor is further configured such that the UE measures a channel on the one or more sets of CSI-RS ports, and wherein the processor is further configured such that the UE transmits one or more feedback signals to one or more of the TPs, wherein the feedback signals contain one or more parameters indicative of the condition of the channel.

22 . The UE of claim 21 , wherein the one or more parameters comprise channel state information CSI.

23 . The UE of claim 21 , wherein each of the TPs is deployed in one or more of a homogeneous network or a heterogeneous network.

24 . The UE of claim 21 , wherein receiving the information comprises receiving a set of one or more CSI-RS ports transmitted from one or more TPs.