Method, system and apparatus for downlink shared channel reception in cooperative multipoint transmissions

1. A method implementable in a wireless transmit/receive unit (WTRU) in communication with a plurality of transmission (Tx) points, comprising:

receiving radio resource control (RRC) signaling including first and second parameters of a demodulation reference signals (DM-RS) configuration associated with the plurality of Tx points;

receiving, on a downlink control channel associated with a forthcoming coordinated downlink transmission to the WTRU, downlink control information including an indication of an antenna port index, scrambling identity and number of layers;

determining the scrambling identity based on the indication and on whether a single codeword of a plurality of codewords is enabled or multiple codewords of the plurality of codewords are enabled;

on condition that the scrambling identity is determined to be a first value:

selecting the first parameter; and

generating a first DM-RS sequence for receiving DM-RS of the coordinated downlink transmission using the first parameter and the first value of the scrambling identity as inputs for initializing the first DM-RS sequence; and

on condition that the scrambling identity is determined to be a second value:

selecting the second parameter; and

generating a second DM-RS sequence for receiving DM-RS of the coordinated downlink transmission using the second parameter and the second value of the scrambling identity as inputs for initializing the second DM-RS sequence.

2. The method of claim 1 , further comprising: provisioning the first and second parameters into the WTRU.

3. The method of claim 1 , wherein the indication is multiple bits.

4. The method of claim 1 , further comprising:

receiving the coordinated downlink transmission based, at least in part, on the first DM-RS sequence or the second DM-RS sequence.

5. The method of claim 4 , wherein receiving the coordinated downlink transmission comprises receiving the DM-RS of the coordinated downlink transmission based, at least in part, on the first DM-RS sequence or the second DM-RS sequence.

6. The method of claim 1 , wherein each of the first and second parameters comprises: any of an index of antenna ports specific to the WTRU, a value specific to the WTRU for an initialization sequence for reference-signal generation, a transmission mode specific to the WTRU, an identifier specific to the WTRU for use with initializing a reference-signal sequence, and a value based on the DM-RS configuration associated with the plurality of Tx points.

7. The method of claim 1 , wherein each of the first and second values of the scrambling identity comprises: a value of any of a scrambling identity configured using layers above a physical layer, an identity of the WTRU, a radio network temporary identifier (RNTI) of the WTRU, an identity of a transmission point, an identity of a cell of a transmission Tx point, a carrier indicator field (CIF), and a scrambling identity of one or more antenna ports.

8. The method of claim 1 , wherein the downlink control information comprises: at least one bit for explicitly signaling to the WTRU that the coordinated downlink transmission to the WTRU is forthcoming.

9. The method of claim 1 , wherein the downlink control information comprises: at least one bit implicitly signaling to the WTRU that the coordinated downlink transmission to the WTRU is forthcoming.

10. The method of claim 1 , wherein the downlink control information comprises: any of an explicit and implicit signal obtained by way of blind detection of the downlink control channel.

11. The method of claim 1 , wherein initializing the first DM-RS sequence is based on initiator, c init =(└n s /2┘+1)·(2X ID +1)·2 16 +Y ID , and wherein:

for the first DM-RS sequence, X ID is the first parameter, wherein n s is a slot number, and wherein Y ID is the first value of the scrambling identity.

12. The method of claim 11 , wherein initializing the second DM-RS sequence is based on the initiator, c init =(└n s /2┘+1)·(2X ID +1)·2 16 +Y ID , and wherein:

for the second DM-RS sequence, X ID is the second parameter, wherein n s is a slot number, and wherein Y ID is the second value of the scrambling identity.

13. The method of claim 1 , wherein initializing the second DM-RS sequence is based on initiator, c init =(└n s /2┘+1)·(2X ID +1)·2 16 +Y ID , and wherein:

for the second DM-RS sequence, X ID is the second parameter, wherein n s is a slot number, and wherein Y ID is the second value of the scrambling identity.

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

a receiver configured to:

receive radio resource control (RRC) signaling including first and second parameters of a demodulation reference signals (DM-RS) configuration associated with the plurality of Tx points;

receive, on a downlink control channel associated with a forthcoming coordinated downlink transmission to the WTRU, downlink control information including an indication of an antenna port index, a scrambling identity and number of layers; and

a processor configured to:

determine the scrambling identity based on the indication and on whether a single codeword of a plurality of codewords is enabled or multiple codewords of the plurality of codewords are enabled;

on condition that the scrambling identity is determined to be a first value:

select the first parameter; and

generate a first DM-RS sequence for receiving DM-RS of the coordinated downlink transmission using the first parameter and the first value of the scrambling identity as inputs for initializing the first DM-RS sequence; and

on condition that the scrambling identity is determined to be a second value:

select the second parameter; and

generate a second DM-RS sequence for receiving DM-RS of the coordinated downlink transmission using the second parameter and the second value of the scrambling identity as inputs for initializing the second DM-RS sequence.

15. The WTRU of claim 14 , wherein the WTRU comprises a memory, and wherein the processor is further configured to provision the first and second parameters into the memory.

16. The WTRU of claim 14 , wherein the indication is multiple bits.

17. The WTRU of claim 14 , wherein the receiver is configured to receive the coordinated downlink transmission based, at least in part, on the first DM-RS sequence or the second DM-RS sequence.

18. The WTRU of claim 17 , wherein the receiver being configured to receive the coordinated downlink transmission comprises the receiver being configured to receive the DM-RS of the coordinated downlink transmission based, at least in part, on the first DM-RS sequence or the second DM-RS sequence.

19. The WTRU of claim 14 , wherein each of the first and second parameters comprises: any of an index of antenna ports specific to the WTRU, a value specific to the WTRU for an initialization sequence for reference-signal generation, a transmission mode specific to the WTRU, an identifier specific to the WTRU for use with initializing a reference-signal sequence, and a value based on the DM-RS configuration associated with the plurality of Tx points.

20. The WTRU of claim 14 , wherein each of the first and second values of the scrambling identity comprises: a value of any of a scrambling identity configured using layers above a physical layer, an identity of the WTRU, a radio network temporary identifier (RNTI) of the WTRU, an identity of a transmission point, an identity of a cell of a transmission Tx point, a carrier indicator field (CIF), and a scrambling identity of one or more antenna ports.

21. The WTRU of claim 14 , wherein the downlink control information comprises: at least one bit for explicitly signaling to the WTRU that the coordinated downlink transmission to the WTRU is forthcoming.

22. The WTRU of claim 14 , wherein the downlink control information comprises: at least one bit implicitly signaling to the WTRU that the coordinated downlink transmission to the WTRU is forthcoming.

23. The WTRU of claim 14 , wherein the downlink control information comprises: any of an explicit and implicit signal obtained by way of blind detection of the downlink control channel.

24. The WTRU of claim 14 , wherein initializing the first DM-RS sequence is based on initiator, c init =(└n s /2┘+1)·(2X ID +1)·2 16 +Y ID , and wherein:

for the first DM-RS sequence, X ID is the first parameter, wherein n s is a slot number, and wherein Y ID is the first value of the scrambling identity.

25. The WTRU of claim 24 , wherein initializing the second DM-RS sequence is based on the initiator, c init =(└n s /2┘+1)·(2X ID +1)·2 16 +Y ID and wherein:

for the second DM-RS sequence, X ID is the second parameter, wherein n s is a slot number, and wherein Y ID is the second value of the scrambling identity.

26. The WTRU of claim 14 , wherein initializing the second DM-RS sequence is based on initiator, c init =(└n s /2┘+1)·(2X ID +1)·2 16 +Y ID , and wherein:

for the second DM-RS sequence, X ID is the second parameter, wherein n s is a slot number, and wherein Y ID is the second value of the scrambling identity.

27. A method comprising:

receiving, at each transmission (Tx) point of a plurality of Tx points:

first and second parameters of a demodulation reference signals (DM-RS) configuration associated with the plurality of Tx points; and

an antenna port index, a scrambling identity and number of layers associated with an upcoming coordinated downlink transmission to a wireless transmit/receive unit (WTRU);

on condition that the scrambling identity has a first value:

selecting the first parameter; and

generating, at the plurality of Tx points, a first DM-RS sequence for DM-RS of the coordinated downlink transmission using the first parameter and the first value of the scrambling identity as inputs for initializing the first DM-RS sequence;

on condition that the scrambling identity has a second value;

selecting the second parameter; and

generating, at the plurality of Tx points, a second DM-RS sequence for DM-RS of the coordinated downlink transmission using the second parameter and the second value of the scrambling identity as inputs for initializing the second DM-RS sequence;

transmitting, to the WTRU from at least one of the plurality of Tx points, radio resource control (RRC) signaling including the first and second parameters; and

transmitting, to the WTRU from at least one of the plurality of Tx points, downlink control information associated with the upcoming coordinated downlink transmission to the WTRU, wherein:

the downlink control information includes an indication of the antenna port index, first value of the scrambling identity and number of layers; and

the downlink control information includes multiple bits indicative of whether a single codeword of a plurality of codewords is enabled or multiple codewords of the plurality of codewords are enabled.

28. The method of claim 27 , wherein the indication is multiple bits.

29. The method of claim 27 , further comprising:

transmitting the coordinated downlink transmission.

30. The method of claim 27 , wherein the downlink control information comprises: at least one bit for explicitly signaling to the WTRU that the coordinated downlink transmission to the WTRU is forthcoming.

31. The method of claim 27 , wherein the downlink control information comprises: at least one bit implicitly signaling to the WTRU that the coordinated downlink transmission to the WTRU is forthcoming.

32. The method of claim 27 , wherein the downlink control information comprises: any of an explicit and implicit signal obtainable by way of blind detection of the downlink control channel.

33. A system comprising a plurality of transmission (Tx) points configured to:

receive, at each transmission (Tx) point of the plurality of Tx points:

first and second parameters of a demodulation reference signals (DM-RS) configuration associated with the plurality of Tx points; and

an antenna port index, a scrambling identity and number of layers associated with an upcoming coordinated downlink transmission to a wireless transmit/receive unit (WTRU);

on condition that the scrambling identity has a first value;

select the first parameter; and

generate, at the plurality of Tx points, a first DM-RS sequence for DM-RS of the coordinated downlink transmission using the first parameter and the first value of the scrambling identity as inputs for initializing the first DM-RS sequence;

on condition that the scrambling identity has a second value;

select the second parameter; and

generate, at the plurality of Tx points, a second DM-RS sequence for DM-RS of the coordinated downlink transmission using the second parameter and the second value of the scrambling identity as inputs for initializing the second DM-RS sequence;

transmit, to the WTRU from at least one of the plurality of Tx points, radio resource control (RRC) signaling including the first and second parameters; and

transmit, to the WTRU from at least one of the plurality of Tx points, downlink control information associated with the coordinated downlink transmission to the WTRU, wherein:

the downlink control information includes an indication of the antenna port index, first value of the scrambling identity and number of layers; and

the downlink control information includes multiple bits indicative of whether a single codeword of a plurality of codewords is enabled or multiple codewords of the plurality of codewords are enabled.

34. The system of claim 33 , wherein the indication is multiple bits.

35. The system of claim 33 , wherein the plurality of transmission (Tx) points is further configured to transmit the coordinated downlink transmission.

36. The system of claim 33 , wherein the downlink control information comprises: at least one bit for explicitly signaling to the WTRU that the coordinated downlink transmission to the WTRU is forthcoming.

37. The system of claim 33 , wherein the downlink control information comprises: at least one bit implicitly signaling to the WTRU that the coordinated downlink transmission to the WTRU is forthcoming.

38. The system of claim 33 , wherein the downlink control information comprises: any of an explicit and implicit signal obtainable by way of blind detection of the downlink control channel.

39. The method of claim 1 , wherein the downlink control information includes multiple bits indicative of whether a single codeword of a plurality of codewords is enabled or multiple codewords of the plurality of codewords are enabled.

40. The method of claim 1 , wherein the downlink control channel comprises any of a physical downlink control channel (PDCCH) and an enhanced PDCCH (ePDCCH).

41. The method of claim 1 , wherein the coordinated downlink transmission comprises a physical downlink shared channel (PDSCH).

42. The method of claim 1 , further comprising:

receiving the DM-RS of the coordinated downlink transmission; and

performing channel estimation using the received DM-RS.

43. The method of claim 42 , further comprising:

receiving data transmitted in the coordinated downlink transmission based on the channel estimation.

44. The WTRU of claim 14 , wherein the downlink control information includes multiple bits indicative of whether a single codeword of a plurality of codewords is enabled or multiple codewords of the plurality of codewords are enabled.

45. The WTRU of claim 14 , wherein the downlink control channel comprises any of a physical downlink control channel (PDCCH) and an enhanced PDCCH (ePDCCH).

46. The WTRU of claim 14 , wherein the coordinated downlink transmission comprises a physical downlink shared channel (PDSCH).

47. The WTRU of claim 14 , wherein:

the receiver is configured to receive the DM-RS of the coordinated downlink transmission; and

the processor is configured to perform channel estimation using the received DM-RS.

48. The WTRU of claim 47 , wherein the processor is configured to receive data transmitted in the coordinated downlink transmission based on the channel estimation.

49. The method of claim 27 , wherein initializing the first DM-RS sequence is based on initiator, c init =(└n s /2┘+1)·(2X ID +1)·2 16 +Y ID , and wherein:

for the first DM-RS sequence, X ID is the first parameter, wherein n s is a slot number, and wherein Y ID is the first value of the scrambling identity.

50. The method of claim 49 , wherein initializing the second DM-RS sequence is based on the initiator, c init =(└n s /2┘+1)·(2X ID +1)·2 16 +Y ID , and wherein:

for the second DM-RS sequence, X ID is the second parameter, wherein n s is a slot number, and wherein Y ID is the second value of the scrambling identity.

51. The method of claim 27 , wherein initializing the second DM-RS sequence is based on initiator, c init =(└n s /2┘+1)·(2X ID +1)·2 16 +Y ID , wherein:

for the second DM-RS sequence, X ID is the second parameter, wherein n s is a slot number, and wherein Y ID is the second value of the scrambling identity.

52. The system of claim 33 , wherein initializing the first DM-RS sequence is based on initiator, c init =(└n s /2┘+1)·(2X ID +1)·2 16 +Y ID , and wherein:

for the first DM-RS sequence, X ID is the first parameter, wherein n s is a slot number, and wherein Y ID is the first value of the scrambling identity.

53. The system of claim 52 , wherein initializing the second DM-RS sequence is based on the initiator, c init =(└n s /2┘+1)·(2X ID +1)·2 16 +Y ID , and wherein:

for the second DM-RS sequence, X ID is the second parameter, wherein n s is a slot number, and wherein Y ID is the second value of the scrambling identity.

54. The system of claim 33 , wherein initializing the second DM-RS sequence is based on initiator, c init =(└n s /2┘+1)·(2X ID +1)·2 16 +Y ID , and wherein:

for the second DM-RS sequence, X ID is the second parameter, wherein n s is a slot number, and wherein Y ID is the second value of the scrambling identity.