Code Optimization for a Code-Modulated RF Front End

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.