Methods and Apparatus for Link Adaptation for Single User and Multi-User Mimo

A method of performing link adaptation in a wireless communication system for simultaneous retransmission of first and second codewords over first and second multiple input-multiple output (MIMO) communication channels, the method comprising:

• determining transport block sizes for the first and second codewords used in an initial transmission of the first and second codewords;
• mapping the codeword with the larger transport block size to a MIMO communication channel of the first and second MIMO communication channels having the higher channel quality;
• selecting scheduling blocks for the first and second codewords;
• determining modulation and coding scheme (MCS) levels for retransmission of the first and second codewords;
• determining transport block sizes for retransmission of the first and second codewords;
• determining if there is a need to increase the number of scheduling blocks in at least one codeword of the first and second codewords;
• adding scheduling blocks to the at least one codeword in response to determining that there is a need to increase the number of scheduling blocks in the at least one codeword;
• re-computing the transport block size for the at least one codeword;
• and
• simultaneously transmitting the first and second codewords over different MIMO communication channels using the same time and frequency resources.

A method of performing link adaptation in a wireless communication system for simultaneous retransmission of an old codeword and transmission of a new codeword over first and second multiple input-multiple output (MIMO) communication channels, the method comprising:

• performing single codeword link adaptation for the old codeword;
• selecting a modulation and coding scheme (MCS) level for the new codeword;
• determining if a transport block size for the new codeword is less than a minimum transport block size, and in response, increasing the MCS level for the new codeword;
• determining if the transport block size for the new codeword is greater than a size of data to be transmitted in the new codeword, and in response, decreasing the MCS level for the new codeword;
• and
• simultaneously transmit the first and second codewords over different multiple input-multiple output (MIMO) communication channels using the same time and frequency resources.

A network node of a radio access network, the network node comprising:

• a scheduler that is configured to:
• select initial modulation and coding scheme (MCS) levels for first and second codewords;
• estimate a size ratio of the first and second codewords;
• determine a number of scheduling blocks for the first and second codewords with the initial modulation and coding schemes;
• determine revised MCS levels for the first and second codewords in response to the selected scheduling blocks;
• compute transport block sizes for the codewords in response to the revised modulation and coding schemes for the first and second codewords;
• determine if there is a need to increase the number of scheduling blocks in at least one codeword of the first and second of the codewords;
• add scheduling blocks to the at least one codeword in response to determining that there is a need to increase the number of scheduling blocks in the at least one codeword;
• and
• re-compute the transport block for the at least one codeword;
• and
• a transmitter that is configured to simultaneously transmit the first and second codewords over different multiple input-multiple output (MIMO) communication channels using the same time and frequency resources.

A network node of a radio access network, the network node comprising:

• a scheduler that is configured to:
• determine transport block sizes for first and second codewords used in an initial transmission of the first and second codewords;
• map the codeword with the larger transport block size to a MIMO communication channel of the first and second MIMO communication channels having the higher channel quality;
• select scheduling blocks for the first and second codewords;
• determine modulation and coding scheme (MCS) levels for retransmission of the first and second codewords;
• determine transport block sizes for retransmission of the first and second codewords;
• determine if there is a need to increase the number of scheduling blocks in at least one codeword of the first and second codewords;
• add scheduling blocks to the at least one codeword in response to determining that there is a need to increase the number of scheduling blocks in the at least one codeword;
• and
• re-compute the transport block for the at least one codeword;
• and
• a transmitter that is configured to simultaneously re-transmit the first and second codewords over different MIMO communication channels using the same time and frequency resources.

A network node of a radio access network, the network node comprising:

• a scheduler that is configured to:
• perform single codeword link adaptation for a previously transmitted old codeword;
• select a modulation and coding scheme (MCS) level for a new codeword;
• determine if a transport block size for the new codeword is less than a minimum transport block size, and in response, increase the MCS level for the new codeword;
• and
• determine if the transport block size for the new codeword is greater than a size of data to be transmitted in the new codeword, and in response, decrease the MCS level for the new codeword;
• and
• a transmitter that is configured to simultaneously transmit the old and new codewords over different multiple input-multiple output (MIMO) communication channels using the same time and frequency resources.