{"title":"A quantized reliability-relay selection method for wireless cooperative communications","authors":"Wassim Alexan, A. El-Mahdy","doi":"10.1109/ISWCS.2014.6933369","DOIUrl":null,"url":null,"abstract":"In this paper, we propose a relay selection method for cooperative communication systems (CCS) employing the QPSK modulation scheme. The relay nodes forward their reliability to the destination node, utilizing a quantized reliability-relaying (QRR) scheme. The reliability is divided into five different levels by the relay nodes, according to the log-likelihood ratio (LLR) value of the received signal from the source node. Then, a suitable symbol is forwarded to the destination node if the relay node is set as active. A relay node is set as active if the reliability of the received signal is beyond a certain threshold. We provide analysis of the LLR for QPSK and carry out numerical simulations comparing the bit error rate (BER) of the QRR method against regular decode-and-forward (DF) and the best relay selection algorithms. A channel estimation algorithm is utilized to evaluate the performance of the system, as well as calculations of the normalized mean squared error (NMSE) of the channels. The special case of a system employing BPSK is also investigated.","PeriodicalId":431852,"journal":{"name":"2014 11th International Symposium on Wireless Communications Systems (ISWCS)","volume":"45 1","pages":"0"},"PeriodicalIF":0.0000,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"6","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"2014 11th International Symposium on Wireless Communications Systems (ISWCS)","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1109/ISWCS.2014.6933369","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 6
Abstract
In this paper, we propose a relay selection method for cooperative communication systems (CCS) employing the QPSK modulation scheme. The relay nodes forward their reliability to the destination node, utilizing a quantized reliability-relaying (QRR) scheme. The reliability is divided into five different levels by the relay nodes, according to the log-likelihood ratio (LLR) value of the received signal from the source node. Then, a suitable symbol is forwarded to the destination node if the relay node is set as active. A relay node is set as active if the reliability of the received signal is beyond a certain threshold. We provide analysis of the LLR for QPSK and carry out numerical simulations comparing the bit error rate (BER) of the QRR method against regular decode-and-forward (DF) and the best relay selection algorithms. A channel estimation algorithm is utilized to evaluate the performance of the system, as well as calculations of the normalized mean squared error (NMSE) of the channels. The special case of a system employing BPSK is also investigated.