Methods and apparatus for multi-user MIMO transmissions in wireless communication systems
A wireless communication system includes a base station capable of communicating with a plurality of subscriber stations. The base station can transmit control information and data to a subscriber stations. The base station also can identify a set of RS patterns to be used to communicate with the subscriber station, assign a subset of antenna port numbers within the set of RS patterns to the subscriber stations. The base station can indicate the assigned states in a Downlink Control Information (DCI) format transmitted in a Physical Downlink Control Channel (PDCCH). The base station transmits the data using a subset of antenna ports corresponding to the subset of antenna port numbers. The base station also can map reference signals corresponding to the subset of antenna ports according to at least one RS pattern within the set of RS patterns.
1. A method for communicating with a plurality of subscriber stations, the method comprising:
transmitting a downlink grant downlink control information (DCI) format and data in a subframe from a base station to at least one of the plurality of subscriber stations,
wherein the downlink grant DCI format is configured to schedule a Physical Downlink Shared CHannel (PDSCH) with one or two enabled codewords,
wherein the downlink grant DCI format comprises a 3-bit field indicating at least a number of antenna ports for the PDSCH, a corresponding set of indices for the antenna ports, and a scrambling identifier (ID), and
wherein, when the PDSCH is scheduled with two enabled codewords, a state of the 3-bit field indicates the number of antenna ports as follows:
State of the 3-bit field
Number
2
3
3
4
4
5
5
6
6
7
7
8.
2. The method as set forth in claim 1 , wherein, when the PDSCH is scheduled with two enabled codewords, the state of the 3-bit field further indicates the number of antenna ports as follows:
State of the 3-bit field
Number
0
2
1
2.
3. The method as set forth in claim 1 , wherein, when the PDSCH is scheduled with one enabled codeword, the state of the 3-bit field indicates the antenna port indices and the scrambling ID as follows:
State of the 3-bit field
Antenna Port Indices
Scrambling ID
0
7
0
1
7
1
2
8
0
3
8
1.
4. A base station, comprising:
a transmitter configured to transmit a downlink grant downlink control information (DCI) format and data in a subframe to at least one of a plurality of subscriber stations,
wherein the downlink grant DCI format is configured to schedule a Physical Downlink Shared CHannel (PDSCH) with one or two enabled codewords,
wherein the downlink grant DCI format comprises a 3-bit field indicating at least a number of antenna ports for the PDSCH, a corresponding set of indices for the antenna ports, and a scrambling identifier (ID), and
wherein, when the PDSCH is scheduled with two enabled codewords, a state of the 3-bit field indicates the number of antenna ports as follows:
State of the 3-bit field
Number
2
3
3
4
4
5
5
6
6
7
7
8.
5. The base station as set forth in claim 4 , wherein, when the PDSCH is scheduled with two enabled codewords, the state of the 3-bit field further indicates the number of antenna ports as follows:
State of the 3-bit field
Number
0
2
1
2.
6. The base station as set forth in claim 4 , wherein, when the PDSCH is scheduled with one enabled codeword, the state of the 3-bit field indicates the antenna port indices and the scrambling ID as follows:
State of the 3-bit field
Antenna Port Indices
Scrambling ID
0
7
0
1
7
1
2
8
0
3
8
1.
7. A method for communicating with a base station, the method comprising:
receiving a downlink grant downlink control information (DCI) format and data in a subframe at a subscriber station from a base station,
wherein the downlink grant DCI format is configured to schedule a Physical Downlink Shared CHannel (PDSCH) with one or two enabled codewords,
wherein the downlink grant DCI format comprises a 3-bit field indicating at least a number of antenna ports for the PDSCH, a corresponding set of indices for the antenna ports, and a scrambling identifier (ID), and
wherein, when the PDSCH is scheduled with two enabled codewords, a state of the 3-bit field indicates the number of antenna ports as follows:
State of the 3-bit field
Number
2
3
3
4
4
5
5
6
6
7
7
8.
8. The method as set forth in claim 7 , wherein, when the PDSCH is scheduled with two enabled codewords, the state of the 3-bit field further indicates the number of antenna ports as follows:
State of the 3-bit field
Number
0
2
1
2.
9. The method as set forth in claim 7 , wherein, when the PDSCH is scheduled with one enabled codeword, the state of the 3-bit field indicates the antenna port indices and the scrambling ID as follows:
State of the 3-bit field
Antenna Port Indices
Scrambling ID
0
7
0
1
7
1
2
8
0
3
8
1.
10. A subscriber station, comprising:
a receiver configured to receive a downlink grant downlink control information (DCI) format and data in a subframe from a base station,
wherein the downlink grant DCI format is configured to schedule a Physical Downlink Shared CHannel (PDSCH) with one or two enabled codewords,
wherein the downlink grant DCI format comprises a 3-bit field indicating at least a number of antenna ports for the PDSCH, a corresponding set of indices for the antenna ports, and a scrambling identifier (ID), and
wherein, when the PDSCH is scheduled with two enabled codewords, the state of the 3-bit field indicates the number of antenna ports as follows:
State of the 3-bit field
Number
2
3
3
4
4
5
5
6
6
7
7
8.
11. The subscriber station as set forth in claim 10 , wherein, when the PDSCH is scheduled with two enabled codewords, the state of the 3-bit field further indicates the number of antenna ports as follows:
State of the 3-bit field
Number
0
2
1
2.
12. The subscriber station as set forth in claim 10 , wherein, when the PDSCH is scheduled with one enabled codeword, the state of the 3-bit field indicates the antenna port indices and the scrambling ID as follows:
State of the 3-bit field
Antenna Port Indices
Scrambling ID
0
7
0
1
7
1
2
8
0
3
8
1.