Method and system of multi-layer beamforming

1. A base station comprising:

a reference signal sequence generator configured to generate a reference signal sequence for a reference signal for each of n antenna ports using one initialization seed c init , n being a positive integer,

wherein the initialization seed is defined as:

c init =(└ n s /2┘+1)·(2 N ID cell +1)·2 16 +N ID group ,

where n s is a first slot number in a subframe, N ID cell is a cell identifier of the base station, and N ID group is a group identifier; and

a transmit path circuitry configured to transmit a downlink grant and the reference signal.

2. The base station in accordance with claim 1 wherein the group identifier N ID group is a one-bit group identifier dynamically indicated in a codepoint in the downlink grant transmitted by the base station.

3. The base station in accordance with claim 2 wherein the codepoint indicating the one-bit group identifier N ID group is one of the following codepoints defined in DCI format 2 A: a transport block to codeword (TB-to-CW) swap bit and a new data indicator (NDI) bit of a disabled transport block (TB), and

wherein the other of the codepoints defined DCI format 2 A that is not used to indicate the one-bit group identifier N ID group is used to indicate a stream index.

4. The base station in accordance with claim 2 wherein the one-bit group identifier N ID group is indicated by a transport block to codeword (TB-to-CW) swap bit defined in DCI format 2 A, and a stream index is indicated by a new data indicator (NDI) bit of a disabled transport block (TB) defined in DCI format 2 A.

5. The base station in accordance with claim 2 wherein the one-bit group identifier N ID group and a stream index are indicated by a transport block to codeword (TB-to-CW) swap bit and a new data indicator (NDI) bit of a disabled transport block (TB) defined in DCI format 2 A as follows:

Reinterpreted

Reinterpreted NDI bit

TB-to-CW swap bit

of the disabled TB

(group id, stream id)

0

0

(0, 0)

0

1

(0, 1)

1

0

(1, 0)

1

1

(1, 1)

6. A method of operating a base station, the method comprising:

generating, at a reference signal sequence generator, a reference signal sequence for a reference signal for each of n antenna ports using one initialization seed c init , n being a positive integer,

wherein the initialization seed is defined as:

c init =(└ n s /2┘+1)·(2 N ID cell +1)·2 16 +N ID group ,

where n s is a first slot number in a subframe, N ID cell is a cell identifier of the base station, and N ID group is a group identifier; and

transmitting a downlink grant and the reference signal.

7. The method in accordance with claim 6 wherein the group identifier N ID group is a one-bit group identifier dynamically indicated in a codepoint in the downlink grant transmitted by the base station.

8. The method in accordance with claim 7 wherein the codepoint indicating the one-bit group identifier N ID group is one of the following codepoints defined in DCI format 2 A: a transport block to codeword (TB-to-CW) swap bit and a new data indicator (NDI) bit of a disabled transport block (TB), and

wherein the other of the codepoints defined DCI format 2 A that is not used to indicate the one-bit group identifier N ID group is used indicate a stream index.

9. The method in accordance with claim 7 wherein the one-bit group identifier N ID group is indicated by a transport block to codeword (TB-to-CW) swap bit defined in DCI format 2 A, and a stream index is indicated by a new data indicator (NDI) bit of a disabled transport block (TB) defined in DCI format 2 A.

10. The method in accordance with claim 7 wherein the one-bit group identifier N ID group and a stream index are indicated by a transport block to codeword (TB-to-CW) swap bit and a new data indicator (NDI) bit of a disabled transport block (TB) defined in DCI format 2 A as follows:

Reinterpreted

Reinterpreted NDI bit

TB-to-CW swap bit

of the disabled TB

(group id, stream id)

0

0

(0, 0)

0

1

(0, 1)

1

0

(1, 0)

1

1

(1, 1)

11. A subscriber station comprising:

a receive path circuitry configured to:

receive a downlink grant from a base station; and

receive a reference signal generated at the base station using one initialization seed c init ,

wherein the initialization seed is defined as:

c init =(└ n s /2┘+1)·(2 N ID cell +1)·2 16 +N ID group ,

where n s is a first slot number in a subframe, N ID cell is a cell identifier of the base station, and N ID cell is a identifier.

12. The subscriber station in accordance with claim 11 wherein the group identifier N ID group is a one-bit group identifier dynamically indicated in a codepoint in the downlink grant.

13. The subscriber station in accordance with claim 12 wherein the codepoint indicating the one-bit group identifier N ID group is one of the following codepoints defined in DCI format 2 A: a transport block to codeword (TB-to-CW) swap bit and a new data indicator (NDI) bit of a disabled transport block (TB), and

wherein the other of the codepoints defined DCI format 2 A that is not used to indicate the one-bit group identifier N ID group is used to indicate a stream index.

14. The subscriber station in accordance with claim 12 wherein the one-bit group identifier N ID group is indicated by a transport block to codeword (TB-to-CW) swap bit defined in DCI format 2 A, and a stream index is indicated by a new data indicator (NDI) bit of a disabled transport block (TB) defined in DCI format 2 A.

15. The subscriber station in accordance with claim 12 wherein the one-bit group identifier N ID group and a stream index are indicated by a transport block to codeword (TB-to-CW) swap bit and a new data indicator (NDI) bit of a disabled transport block (TB) defined in DCI format 2 A as follows:

Reinterpreted

Reinterpreted NDI bit

TB-to-CW swap bit

of the disabled TB

(group id, stream id)

0

0

(0, 0)

0

1

(0, 1)

1

0

(1, 0)

1

1

(1, 1)

16. A method of operating a subscriber station, the method comprising:

receiving a downlink grant from a base station; and

receiving a reference signal generated at the base station using one initialization seed c init ,

wherein the initialization seed is defined as:

c init =(└ n s /2┘+1)·(2 N ID cell +1)·2 16 +N ID group ,

where n s is a first slot number in a subframe, N ID cell is a cell identifier of the base station, and N ID group is a group identifier.

17. The method in accordance with claim 16 wherein the group identifier N ID group is a one-bit group identifier dynamically indicated in a codepoint in the downlink grant.

18. The method in accordance with claim 17 wherein the codepoint indicating the one-bit group identifier N ID group is one of the following codepoints defined in DCI format 2 A: a transport block to codeword (TB-to-CW) swap bit and a new data indicator (NDI) bit of a disabled transport block (TB), and

wherein the other of the codepoints defined DCI format 2 A that is not used to indicate the one-bit group identifier N ID group is used to indicate a stream index.

19. The method in accordance with claim 17 wherein the one-bit group identifier N ID group is indicated by a transport block to codeword (TB-to-CW) swap bit defined in DCI format 2 A, and a stream index is indicated by a new data indicator (NDI) bit of a disabled transport block (TB) defined in DCI format 2 A.

20. The method in accordance with claim 17 wherein the one-bit group identifier N ID group and a stream index are indicated by a transport block to codeword (TB-to-CW) swap bit and a new data indicator (NDI) bit of a disabled transport block (TB) defined in DCI format 2 A as follows:

Reinterpreted

Reinterpreted NDI bit

TB-to-CW swap bit

of the disabled TB

(group id, stream id)

0

0

(0, 0)

0

1

(0, 1)

1

0

(1, 0)

1

1

(1, 1)