Title: Non orthogonal multiple access for DS-CDMA systems

Authors: Raed Alhamad; Hatem Boujemaa

Addresses: Information Technology Department, Saudi Electronic University, 13316, Kingdom of Saudi Arabia ' SUPCOM – COSIM, Higher School of Communiction of Tunis, Raoued Street km 3.5, 2083, Tunisia

Abstract: In direct sequence code division multiple access (DS-CDMA), the symbols of a single user are transmitted over a given spreading code. In this paper, we propose to increase the throughput of CDMA systems using non orthogonal multiple access (NOMA). The base station transmits a combination of N symbols dedicated to N NOMA users using the same spreading code. The ith NOMA user performs despreading then it detects the symbol of weakest user. The ith user performs successive interference cancelation (SIC) to remove the contribution of the signal of weakest user and detects the symbol of the second weakest user. SIC is repeated until the ith user detects its own symbol. We show that CDMA using NOMA offers a larger throughput than CDMA.

Keywords: NOMA; non orthogonal multiple access; DS-CDMA; direct sequence code division multiple access; throughput analysis; optimal power allocation; users ranking; SNR; SINR analysis.

DOI: 10.1504/IJSNET.2021.117484

International Journal of Sensor Networks, 2021 Vol.36 No.4, pp.222 - 228

Received: 06 Jan 2021
Accepted: 12 Jan 2021
Published online: 08 Sep 2021 *

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