Processing a constant amplitude sequence for transmission

A wireless communication network node comprising processing circuitry, and characterized by the processing circuitry being operative to:

• extend a constant amplitude sequence by adding to the sequence one or more complex-valued elements that have the same amplitude as other complex-valued elements in the sequence;
• upsample the extended sequence by linearly interpolating a difference in phase between adjacent complex-valued elements in the extended sequence;
• and
• limit a bandwidth of the upsampled sequence by low pass filtering the upsampled sequence;
• wherein extending the constant amplitude sequence comprises extending the constant amplitude sequence by a smallest amount needed for the extended sequence to have a length that is an integer factor of a target length of the upsampled sequence, and
• wherein the target length of the upsampled sequence corresponds to a sampling rate with which the upsampled sequence is to be sampled at baseband.

An apparatus operative to generate a constant amplitude sequence, comprising:

• a first module operative to extend the constant amplitude sequence by adding to the sequence one or more complex-valued elements that have the same amplitude as other complex-valued elements in the sequence;
• a second module operative to upsample the extended sequence by linearly interpolating a difference in phase between adjacent complex-valued elements in the extended sequence;
• and
• a third module operative to limit a bandwidth of the upsampled sequence by low pass filtering the ups upsampled sequence;
• wherein the first module is operative to extend the constant amplitude sequence by a smallest amount needed for the extended sequence to have a length that is an integer factor of a target length of the upsampled sequence, and
• wherein the target length of the upsampled sequence corresponds to a sampling rate with which the upsampled sequence is to be sampled at baseband.