Wireless Relay Network Based On Network Coding:Strategies And Performance Analysis

Cooperative communications is a specific area of wireless communication that has been extensively explored within the last decade. The concept of cooperative communications (relay network (RN)) builds upon a network architecture where nodes assist each other to realize spatial advantages of diversity. However, ever since the RN emerges, it has led to introduce new challenges i.e., low reliability, limited throughput, coverage area, service's quality and high data rate. Meanwhile, the network coding (NC) approach was established to be an efficient technique to address same challenges. Motivated by these problems, this study deals with an alternative design and presents the analytical solutions that address these issues.The contributions of this thesis are Multi-faceted; first, it figures out the joining of NC theory with wireless network. Specifically, classification of NC supported by tutorials as well as the taxonomy of particular relay modes of RN with and without NC has been discussed. It makes a simple fundamental difference with the use of NC at intermediate and source nodes. In addition, it is elaborated that how NC can be plainly integrated into the RN stack to achieve practical measurable gains.Second part of this study deals with the examining of channel capacity and bit error rate (BER) of joint channel coding and NC for wireless network. The network system model is concerned with different channel models using convolutional encoding with Viterbi decoding algorithms. These two schemes differ from each other at the intermediate node where the former scenario i.e. conventional scheme is focused on the making of hard\soft decision, decoding and re-encoding of received information. In contrast, in the later scenario i.e. proposed scheme, the decoding process shifts to the end of the receiver to make the hard\soft decisions while the combining of two incoming messages by using NC at the intermediate node. Simulation results show that both approaches have achieved the same capacity at high signal-to-noise ratio (SNR) over-all channel models but the proposed scheme outperformed conventional scheme in terms of BER. While considering the objectives of a soft scheme related to achieve better normalized throughput with reliability of information transmission and complexity solution, investigation and analysis of soft decision scheme of NC (SD-NC) at relay in a two-way relay channel has been studied. Similarly, to enhance system performance, Dm-NC scheme has been examined, where it works directly to De-map the received signals, perform combination i.e. NC, map the combination and then forward to the destination. Simulation analysis proves the performance superiority of Dm-NC over analog-NC in AWGN. Furthermore, witching between analog-NC and QDF-NC comes to play an important role in the network environment. Therefore, to reduce the delay and power consumption at relay node, relay is allowed to adapt switching between the analog-NC and QDF-NC schemes. Obtained results have proved that the QDF-NC performs better than analog-NC.Finally, this work provides analytical solution of the dense wireless networks in various models; i.e. two-way relay channel (TWRC) and multiple accesses relay channel (MARC). Simulation results show that the decreasing of symbol error rate (SER) by increasing the number of relay nodes in the case of TWRC with analog-NC. On the other hand, in the case of MARC with DF-NC and analog-NC, the SER and outage probability is obtained and through simulation results, it is observed that the DF-NC has outperformed the analog-NC. Moreover, to improve system performance, optimal power allocation between the two sources and the best relay has been determined that ultimately based on the asymptotic SER over MARC.