Evaluation of Effect of CMA Radius on SOQPSK Equalization

Abstract

In this work we investigate the effect of using different values of the radius in a constant modulus algorithm (CMA) equalizer for shaped offset quadrature-phase shift keying (SOQPSK), which is transmitted using the iNET data packet structure. The iNET packet structure contains known data bits (the preamble and asynchronous marker (ASM) bits) within each data packet, and these are used to initialize a block processing CMA algorithm. Two real-time processing methods are investigated here, which are referred to as the 'Single block processing' and the 'Block-by-block processing' methods. Both processing methods require that a number of data packets be discarded while the CMA equalizer converges. In this work we will investigate the effect on the performance of the CMA equalizer of changing its equalizing radius, and also the effect of processing different numbers of data packets based on the same initialization. Based on the results of these tests, a final choice of parameters will be made and we will produce a bit error rate curve for a single telemetry channel.