Low-Complexity Decoder for Overloaded Uniquely Decodable Synchronous CDMA

doi:10.1109/ACCESS.2022.3170491

Low-Complexity Decoder for Overloaded Uniquely Decodable Synchronous CDMA

2022-01-01

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DOI：10.1109/ACCESS.2022.3170491

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We consider the problem of designing a low-complexity decoder for antipodal uniquely decodable (UD)/errorless code sets for overloaded synchronous code-division multiple access (CDMA) systems, where the number of signals K-max(a) is the largest known for the given code length L. In our complexity analysis, we illustrate that compared to maximum-likelihood (ML) decoder, which has an exponential computational complexity for even moderate code lengths, the proposed decoder has a quasi-quadratic computational complexity. Simulation results in terms of bit-error-rate (BER) demonstrate that the performance of the proposed decoder has only a 1 - 2 dB degradation in signal-to-noise ratio (SNR) at a BER of 10(-3) when compared to ML. Moreover, we derive the proof of the minimum Manhattan distance of such UD codes and we provide the proofs for the propositions; these proofs constitute the foundation of the formal proof for the maximum number users K-max(a) for L = 8.

Keywords:

Uniquely decodable (UD) codes

overloaded CDMA

overloaded binary and ternary spreading spreading codes

Low-Complexity Decoder for Overloaded Uniquely Decodable Synchronous CDMA

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