A Multiple‐Access Time and Frequency Spectrum‐Spreading Modulation

Abstract

In this paper a novel modulation scheme called Carrier Interleaved Multiple Access (CIMA) is proposed. CIMA provides an alternative for multiple-access modulation accommodating resistance to noise and channel interference. The approach is based on polar signaling modulated with an FM-like composite sinusoidal function. The user assigned frequency deviation and modulation index are strictly related and unique. The latter parameters are generated using a nontraditional pseudorandom noise generator (PRNG). This PRNG provides CIMA with low interference capability between cochannels and adjacent channels. CIMA can be considered for a single-user or multiple-access technique. Selected CIMA characteristics are presented. In order to numerically illustrate the effectiveness of the proposed modulation scheme, the performance of CIMA is compared with the conventional direct-sequence spread spectrum binary phase-shift keying (DSSS-BPSK) modulation.

Zipf Distribution Power AllocationAapproach for NOMA Systems

“…Therefore, we can see that NOMA with Zipf PA allows to obtain a very high achievable capacity and outperforms the fair PA and Generalized PA. Figure (6) shows the comparison of the sum rate versus SNR between the three PA methods, with an equal number of users k = 80. The simulation results indicate that for a SNR rate that varies between [130-220 (dB)] Zipf PA presents an obvious performance gain compared to Fair PA and Generalized PA.…”

“…These three segments will unlock three important usage families Enhanced Mobile Broadband (eMBB): enabling very high transmission speeds, Ultra-reliable and low-latency communications (URLL): Concerns applications that require extreme responsiveness and very short network traversal times, and Massive Machine Communications (mMTC): supports a very large number of devices with limited coverage and throughput [5]. Wireless connectivity in mobile communications is directly associated with frequency spectrum and multiple access method [6].The challenge is to increase the number of users, the throughput rate and the spectral efficiency of the system. Various orthogonal and non-orthogonal multiple access methods are being researched and studied.…”