Research On Terminal Pass - Through Technology In New Generation Wireless Communication System

With the rapid development of wireless communication, mobile communication plays an more and more important role in people’s life, the demand of future communication is becoming higher. Device-to-Device (D2D) can improve the communication system performance. It is also a candidate of new generation of wireless communication system. Users can use D2D to communicate directly without Base station. This paper is based on the survey of D2D and researches the link adaptation scheme and bit rearrangement scheme.In the scenario of D2D multicast which employed network coding, channel quality is different due to the nature of wireless channels. Conventional link adaptation scheme cannot fully explore the spectrum resource because the chosen modulation and coding scheme (MCS) is based on the worst channel quality. This paper proposed a link adaptation scheme which can be used in the scenario of multicast. The chosen MCS is based on the best channel quality in the proposed scheme. It makes specific packet use equivalent lower MCS with bit-mapping to ensure reliability of transmission. The simulation results show that the proposed link adaptation scheme can efficiently improve the spectrum efficiency of D2D multicast with network coding. The scheme can achieve 13% to 45% performance gain in scenarios of different channel qualities.In the D2D cooperative relay system which employed link adaptation, the channel quality of direct link and relay link is independent, so the chosen MCS is different. The conventional intra-symbol bit rearrangement scheme can only achieve limited performance gain because it only considers the MCS of relay link. This paper proposed a novel inter-symbol bit rearrangement scheme which is based on the minimum Euclidean distance. The proposed scheme can be used in the D2D cooperative relay system with different MCSs. It averages the sum of minimum Euclidean distances through switching bit position within several symbols. The average sum of minimum Euclidean distances represents the average bit reliability. The simulation results show that the proposed bit rearrangement scheme outperforms the conventional scheme in frame rate (FER), bit error rate (BER) and system throughput. This proposed scheme can highly improve the decoding performance of D2D cooperative relay system which employed link adaptation.