Compression and de-compression of complex valued OFDM data for a radio base station

A de-compression method comprising:

• receiving an OFDM transmission frame comprising a standard deviation value and a plurality of quantized in-phase and quadrature sample value representations each comprising a second number of bits;
• extracting the standard deviation value;
• extracting the quantized sample value representations;
• for each of the quantized in-phase and quadrature sample value representations, mapping the quantized in-phase or quadrature sample value representation to a reconstruction level scaled by the standard deviation value to produce a reconstructed in-phase or quadrature sample value represented by a third number of bits, wherein the second number of bits are fewer than the third number of bits;
• and
• combining the plurality of reconstructed in-phase and quadrature sample values to a reconstructed time domain complex-valued OFDM data block.

A compressor circuit comprising processing circuitry configured to:

• receive a time domain complex-valued OFDM data block comprising a plurality of complex-valued data samples wherein each complex-valued data sample comprises an in-phase sample value and a quadrature sample value, each represented by a first number, M, of bits;
• determine an absolute sample value of each of the in-phase sample value and the quadrature sample value for each of the complex-valued data samples;
• calculate an average of the absolute sample values of the time domain complex-valued OFDM data block to produce an average absolute sample value;
• map the average absolute sample value to a standard deviation value associated with the absolute sample values based on a mapping function which expresses the average absolute sample value as a first function minus a second function, wherein the first function is a function of the first number of bits and the second function is a sum of 2(M-1)−1 terms, each term comprising a function of the standard deviation value;
• for each of the complex-valued data samples, quantize each of the in-phase sample value and the quadrature sample value using a number of quantization thresholds scaled by the standard deviation value to produce quantized in-phase and quadrature sample value representations, each comprising a second number of bits, wherein the second number of bits are fewer than the first number of bits;
• and
• map the standard deviation value and the quantized in-phase and quadrature sample value representations to an OFDM transmission frame.

A de-compressor comprising processing circuitry configured to:

• receive an OFDM transmission frame comprising a standard deviation value and a plurality of quantized in-phase and quadrature sample value representations each comprising a second number of bits;
• extract the standard deviation value;
• extract the quantized in-phase and quadrature sample value representations;
• for each of the quantized in-phase and quadrature sample value representations, map the quantized in-phase or quadrature sample value representation to a reconstruction level scaled by the standard deviation value to produce a reconstructed in-phase or quadrature sample value represented by a third number of bits, wherein the second number of bits are fewer than the third number of bits;
• and
• combine the plurality of reconstructed in-phase and quadrature sample values to a reconstructed time domain complex-valued OFDM data block.