Multiple demodulation reference signal (DMRS) ports in a code division multiplexing (CDM) group

One or more non-transitory computer-readable storage media storing instructions that, upon execution on a user equipment (UE), configures the UE to perform operations comprising:

• receiving, from a base station, time domain and frequency domain demodulation reference signal (DMRS) parameters indicating a symbol length, DMRS locations, and a configuration type, the symbol length being a single symbol DMRS or a double symbol DMRS, the configuration type being a DMRS configuration type 1 or a DMRS configuration type 2;
• determining that, for uplink DMRS communications or downlink DMRS communications with the base station, a frequency domain orthogonal cover code (FD-OCC) of length three or six and a time domain orthogonal cover code (TD-OCC) are to be used, wherein the TD-OCC is of length three and corresponds to a first TD-OCC sequence of {+1, +1, +1}, a second TD-OCC sequence of {+1, exp(−2j*π/3), exp(−4j*π/3)}, and a third TD-OCC sequence of {+1, exp(−4j*π/3), exp(−2j*π/3)};
• and
• performing the uplink DMRS communications or the downlink DMRS communications using the FD-OCC, symbol length, and configuration type.

A method comprising:

• sending, to a user equipment (UE), time domain and frequency domain demodulation reference signal (DMRS) parameters indicating a symbol length, four DMRS locations, and a configuration type, the symbol length being a single symbol DMRS or a double symbol DMRS, the configuration type being a DMRS configuration type 1 or a DMRS configuration type 2;
• determining that, for uplink DMRS communications or downlink DMRS communications with the UE a frequency domain orthogonal cover code (FD-OCC) of length three or six and a time domain orthogonal cover code (TD-OCC) are to be used, wherein the TD-OCC is of length four and corresponds to TD-OCC sequences of {+1, +1, +1, +1}, {+j, −1, −j, +1}, {+1, −1, +1, −1}, and {−j, −1, +j, +1};
• and
• performing the uplink DMRS communications or the downlink DMRS communications using the FD-OCC, symbol length, and configuration type.