Enhancement of Code-Division Multiplexing Design for Demodulation Reference Signals

A method, performed by a communication device, for generating a demodulation reference signal (DMRS) comprising one or more ports for a physical channel, the method comprising:

• generating and mapping a bit sequence to a first sequence r(q), the first sequence being a real- or complex-valued sequence;
• obtaining a second sequence cf({tilde over (k)}), where {tilde over (k)}=0, 1, . . . , L−1 for a port p of the DMRS, the second sequence being at least one of the following:
• a column or a row of a Discrete Fourier Transform (DFT)-based matrix such as a DFT matrix or an Inverse DFT matrix of size L×L;
• a column or a row of a Discrete Cosine Transform (DCT)-based matrix of size L×L;
• a column or a row of a Hadamard matrix of size L×L;
• or
• a column or a row of any other orthogonal or unitary matrix of size L×L;
• mapping the first and second sequences to L DMRS resource elements of the physical channel for port p which comprises:
• multiplying L entries of the first sequence r(q), element-by-element, with the L entries of the second sequence cf({tilde over (k)}) for the port p to obtain a resulting real- or complex-valued symbol (or real- or complex-valued baseband amplitude) sequence d(i);
• and
• mapping the resulting real- or complex-valued symbol (or the real- or complex-valued baseband amplitude) sequence d(i) to a subset of L DMRS resource elements for the port p from a set of resource elements associated with the DMRS in one or more physical resource blocks (PRBs) of the physical channel, wherein the subset of L DMRS resource elements associated with the port p are all present in a single PRB or in at least two different PRBs.

A method, performed by a communication device, for receiving a physical channel with a demodulation reference signal (DMRS), the DMRS comprising one or more ports, the method comprising processing the received physical channel with the DMRS;

• wherein the DMRS for the physical channel is generated by:
• generating and mapping a bit sequence to a first sequence r(q), the first sequence being a real- or complex-valued sequence;
• and
• obtaining a second sequence cf({tilde over (k)}), where {tilde over (k)}=0, 1, . . . , L−1 for a port p of the DMRS, the second sequence cf({tilde over (k)}) being at least one of the following:
• a column or a row of a Discrete Fourier Transform (DFT)-based matrix such as a DFT matrix or an Inverse DFT matrix of size L×L;
• a column or a row of a Discrete Cosine Transform (DCT)-based matrix of size L×L;
• a column or a row of a Hadamard matrix of size L×L;
• or
• a column or a row of any other orthogonal or unitary matrix of size L×L;
• and
• wherein the DMRS for the physical channel is generated by mapping the first and second sequences to L DMRS resource elements of the physical channel for the port p, which comprises:
• multiplying L entries of the first sequence r(q), element-by-element, with the L entries of the second sequence cf({tilde over (k)}) for the port p to obtain a resulting real- or complex-valued symbol (or the real- or complex-valued baseband amplitude) sequence d(i);
• and
• mapping the resulting real- or complex-valued symbol (or the real- or complex-valued baseband amplitude) sequence d(i) to a subset of L DMRS resource elements for the port p from a set of resource elements associated with the DMRS in one or more physical resource blocks (PRBs) of the physical channel, wherein the subset of L DMRS resource elements associated with the port p are all present in a single PRB or in at least two different PRBs.

A communication device for generating a demodulation reference signal (DMRS) comprising one or more ports for a physical channel, the communication device comprising a processor and a memory containing instructions executable by the processor, whereby the communication device is configured to:

• generate and map a bit sequence to a first sequence r(q), the first sequence being a real- or complex-valued sequence;
• obtain a second sequence cf({tilde over (k)}), where k=0, 1, . . . , L−1 for a port p of the DMRS, the second sequence being at least one of the following:
• a column or a row of a Discrete Fourier Transform (DFT)-based matrix such as a DFT matrix or an Inverse DFT matrix of size L×L;
• a column or a row of a Discrete Cosine Transform (DCT)-based matrix of size L×L;
• a column or a row of a Hadamard matrix of size L×L;
• or
• a column or a row of any other orthogonal or unitary matrix of size L×L;
• and
• map the first and second sequences to L DMRS resource elements of the physical channel for the port p, which comprises being configured to:
• multiply L entries of the first sequence r(q), element-by-element, with the L entries of the second sequence cf({tilde over (k)}) for the port p to obtain a resulting real- or complex-valued symbol (or the real- or complex-valued baseband amplitude) sequence d(i);
• and
• map the resulting real- or complex-valued symbol (or the real- or complex-valued baseband amplitude) sequence d(i) to a subset of L DMRS resource elements for port p from a set of resource elements associated with the DMRS in one or more physical resource blocks (PRBs) of the physical channel, wherein the subset of L DMRS resource elements associated with the port p are all present in a single PRB or in at least two different PRBs.