2014/10/30 by Mohammad Ali Sedaghat, Sedaghat, Mohammad Ali, Ralf R. Müller +3
Computer Science · Engineering · Mathematics · #FOS: Computer and information sciences #Information Theory (cs.IT) #Random Matrices and Applications #Wireless Communication Networks Research #graph theory and CDMA systems
paper · pdf · doi:10.48550/arxiv.1410.8366
openalex publication_date 2014/10/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We extend the result by Tse and Verdú on the optimum asymptotic multiuser efficiency of randomly spread CDMA with Binary Phase Shift Keying (BPSK) input. Random Gaussian and random binary antipodal spreading are considered. We obtain the optimum asymptotic multiuser efficiency of a K-user system with spreading gain N when K and N→∞ and the loading factor, (K)/(N), grows logarithmically with K under some conditions. It is shown that the optimum detector in a Gaussian randomly spread CDMA system has a performance close to the single user system at high Signal to Noise Ratio (SNR) when K and N→∞ and the loading factor, (K)/(N), is kept less than (log3K)/(2). Random binary antipodal matrices are also studied and a lower bound for the optimum asymptotic multiuser efficiency is obtained. Furthermore, we investigate the connection between detecting matrices in the coin weighing problem and optimum asymptotic multiuser efficiency. We obtain a condition such that for any binary input, an N× K random matrix whose entries are chosen randomly from a finite set, is a detecting matrix as K and N→ ∞.