Investigation on iterative multiuser detection physical layer network coding in two-way relay free-space optical links with turbulences and pointing errors

Abstract

Physical layer network coding (PNC) improves the throughput in wireless networks by enabling two nodes to exchange information using a minimum number of time slots. The PNC technique is proposed for two-way relay channel free space optical (TWR-FSO) communications with the aim of maximizing the utilization of network resources. The multipair TWR-FSO is considered in this paper, where a single antenna on each pair seeks to communicate via a common receiver aperture at the relay. Therefore, chip-interleaving is adopted as a technique to separate the different transmitted signals at the relay node to perform PNC mapping. Accordingly, this scheme relies on the iterative multiuser technique for detection of users at the receiver. The bit error rate (BER) performance of the proposed system is examined under the combined influences of atmospheric loss, turbulence-induced channel fading and the pointing errors (PEs). By adopting the joint PNC mapping with interleaving and multiuser detection techniques, the BER results show that the proposed scheme can achieve a significant performance improvement against the degrading effects of turbulences and PEs. It is also demonstrated that a larger number of simultaneous users can be supported with this new scheme in establishing a communication link between multiple pairs of nodes in two time slots, thereby improving the channel capacity.

Performance of orthogonal frequency division multiplexing based M‐ary quadrature amplitude modulation in asymmetrical dual‐hop mixed RF‐FSO transmission system

“…As shown in Figure 1, the RF and FSO links are cascaded. Mobile users use RF links to transmit their data to a relay node, which transmits it to the final destination using the FSO link 11 . The mixed RF‐FSO communication system is recommended for its benefits like high data rate, high efficiency, availability for non‐line of sight (NLoS), and lower implementation complexity 12,13 …”

“…Mobile users use RF links to transmit their data to a relay node, which transmits it to the final destination using the FSO link. 11 The mixed RF-FSO communication system is recommended for its benefits like high data rate, high efficiency, availability for non-line of sight (NLoS), and lower implementation complexity. 12,13 Numerous studies have explained the effect of AT on the achievable FSO system performance.…”

Outage Probability and BER of the Ground to Train Communication Link of a Curved Track in Raining Turbulence with Pointing Errors

“…Considering the distribution of rainfall-induced irradiance fluctuations can be modeled by inverse Gaussian model [9], [10], then the Gamma-Gamma distribution can be approximated by the inverse Gaussian model. Moreover, pointing errors and atmospheric turbulence occur at the same time, and can jointly increase the BER and outage probability [11], which are the main performance indicators of the system and has not been discussed for ground-to-train OWC link. In this paper, we use the inverse Gaussian models to characterize the rain-turbulent-induced irradiance fluctuation of the signal, then model outage probability and BER of the OWC link of the ground-to-train for the train along the curved track.…”