Pilot Signal Design for Mixed Numerology NOMA Transmission

In the fifth-generation mobile communication system (5G) mixed numerology is standardized to meet the requirements of various services. In this paper, mixed numerology signal transmission in which multiple signals with different numerologies is assumed. As a conventional pilot signal, demodulation reference signal (DMRS) in a forth generation mobile communication (4G) is applied. However, under mixed numerology non-orthogonal multiple access (NOMA), DMRS can not realize orthogonality between pilot signals. As a solution, new pilot signal design based on a Zadoff-Chu sequence is proposed. The proposed pilot signal assignment scheme improves orthogonality between signals with different numerologies and, as a result, reduces bit error rate (BER) performance. Numerical results obtained through computer simulation show that the proposed pilot signal assignment scheme improves the performance by about 2.0 dB at a BER of 1$0^{-2}$.