TOA positioning for uplink cooperative NOMA in 5G networks

Wireless geolocation considering Non-Orthogonal Multiple Access (NOMA) is particular of interest for enabling high precision location based services (LBSs) in 5G networks. In this paper, we study the fundamental limits of Time-of-arrival (TOA) positioning for uplink cooperative NOMA in the power domain under different 5G network conditions with special emphasis on the user fairness. The theoretical analysis is conducted in terms of Cramer-Rao Lower Bound (CRLB) expressions. More specifically, the CRLB of TOA positioning for uplink cooperative NOMA and OMA are obtained considering Amplify-and-Forward (AF) and Decode-and-Forward (DF) relaying strategies. Then, the numerical results of both TOA positioning for uplink cooperative NOMA and OMA are obtained and compared under different 5G network scenarios. In particular, the effects of successive interference cancellation (SIC) error, bandwidth, number of relays, and number of UEs and relaying strategy type on the performance of position accuracy are investigated. The results reveal that the cooperative NOMA outperforms cooperative OMA in terms of location estimation accuracy under different network conditions. Furthermore, the results suggest that TOA positioning of cooperative NOMA is a promising choice for supporting high precision LBSs in 5G networks. (C) 2019 Elsevier B.V. All rights reserved.