Research On Wireless Physical Layer Network Coding Based On Electromagnetic Propagation And Free Space Optical Communication

As one of the novel technologies, Network Coding was originallyused in network layer, in order to improve wired multicast networkthroughput. Unlike traditional routing forwarding mechanism of a relay,Network Coding allows multiple sources in a relay node to be encodedbefore being forwarded, for purpose of transferring more information withlimited resources. In the wireless communication system, the broadcastingcharacteristics of the wireless transmission medium provides a goodplatform for the application of Network Coding in physical layer, in orderto optimize network performance even further. Since the concept ofPhysical-Layer Network Coding (PNC) first proposed in2006, theNetwork Coding related technologies have become the hotspots in theresearch area. With the combination of PNC and some key techniques inphysical layer including communication-channel encoding/decoding andmodulation/demodulation, the performance of wireless communicationsystem has also been efficiently improved. However, to keep pace witharising PNC theory, practical use of PNC in wireless communicationsystems with all performance verified has become an essential issue, aswell as a challenging job recently. Thus, by analyzing existing PNCalgorithms, a corresponding finite-domain PNC algorithm has been chosenas the topic in this paper, along with its performance verification andpractical realization.This paper first introduces the fundamental principles of PNCalgorithm and its classification, as well as discussions on several classical algorithms. Meanwhile, through the analysis of various algorithms andtheir existing researches, all the related drawbacks and practical issues arepresented in this paper.Furthermore, this paper explores several projects of combining PNCand other basic communication techniques, proposes the basic scheme ofPNC in general wireless communication system and analyzes the differentengineering factors of communication transmission thereof. As a result ofthe above discussion, also having complexity and implementability takeninto consideration, the traditional PNC algorithm presented by Zhang et al.has been chosen and well studied in this paper. On the basis of the generalwireless frame structure, this paper theoretically proposed the indirectimpacts of frame length to the performance of PNC under differentsynchronization errors, and further analyzed frame length N and samplingclock offset should satisfy some relationship.Finally, based on a wireless bi-directional relay channel model, thispaper has successfully built a platform for the realization of PNC systemby using some experimental instruments, and also presented the systemperformance evaluation for wireless electromagnetic communication andfree space optical communication.