Abstract
Physical layer network coding (PNC) is a promising technique to improve the network throughput in a two-way relay (TWR) channel for two users to exchange messages across a wireless network. The PNC technique incorporating a TWR channel is embraced by a free space optical (FSO) communication link for full utilization of network resources, namely TWR-FSO PNC. In this paper, bit interleaved coded modulation with iterative decoding (BICM-ID) is adopted to combat the deleterious effect of the turbulence channel by saving the message being transmitted to increase the reliability of the system. Moreover, based on this technique, comparative studies between end-to-end BICM-ID code, non-iterative convolutional coded and uncoded systems are carried out. Furthermore, this paper presents the extrinsic information transfer (ExIT) charts to evaluate the performance of BICM-ID code combined with the TWR-FSO PNC system. The simulation results show that the proposed scheme can achieve a significant bit error rate (BER) performance improvement through the introduction of an iterative process between a soft demapper and decoder. Similarly, Monte Carlo simulation results are provided to support the findings. Subsequently, the ExIT functions of the two receiver components are thoroughly analysed for a variety of parameters under the influence of a turbulence-induced channel fading, demonstrating the convergence behaviour of BICM-ID to enable the TWR-FSO PNC system, effectively mitigating the impact of the fading turbulence channel.
Highlights
Network coding has emerged as a new paradigm for communication to provide significantly increased network throughput [1], a valuable expansion technique introduced by [2]known as physical layer network coding (PNC) has an improved throughput for a two-way relay (TWR) network
The inner demapper system is affected by the channel information as it depends on energy per information bit (Eb) /N0 caused by the likelihood ratio (LLR) of Lm a and y, whereas the SISO decoder of PNC with bit interleaved coded modulation with iterative decoding (BICM-ID) starts with a block of independent message bits bk from each user and is encoded by an non-systematic convolutional (NSC) encoder to obtain ck
An evaluation of the link performance is investigated by extrinsic information transfer (ExIT) charts, taking into account the influence of channel impairments such as path loss, atmospheric turbulence fading and pointing errors
Summary
Network coding has emerged as a new paradigm for communication to provide significantly increased network throughput [1], a valuable expansion technique introduced by [2]. Known as physical layer network coding (PNC) has an improved throughput for a two-way relay (TWR) network. The concept of relay-assisted communications has recently been introduced in FSO systems to mitigate the degrading effects of the atmospheric turbulence and improve the system performance in the presence of the non-line-of-sight (NLOS). A number of analytical and simulation studies on the TWR-FSO system have been considered such as the amplify-and-forward (AF) schemes [10], decode-and-forward (DF) [11], linear network-coding at the relay node [12] and a recently-formed concept of buffer-aided relaying in [13]. The result reveals that the TWR-FSO PNC scheme can employ an iterative decoding means to achieve improved performance in terms of bit error rate (BER).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
