Code Optimization for a Code-Modulated RF Front End

Abstract

Recently, a novel class of on-site coding receivers was proposed. The architecture is suitable for digital beamforming in addition to offering multiple-input multiple-output capabilities. Essential to its realization is a code division multiplexing technique aggregating multiple signal paths at the analog front end into a single analog-to-digital converter. As a result, a significant hardware reduction and a higher power efficiency are achieved when compared with the conventional digital beamforming techniques. In this paper, we examine the system's performance with different types of spreading codes, both orthogonal and nonorthogonal, namely Walsh-Hadamard and Gold codes. Bit error rate calculations show that Walsh-Hadamard codes outperform Gold codes in achieving higher dynamic range with less signal-to-noise ratio degradation, assuming a perfectly synchronous system.