Title A Tutorial on Lossy Forwarding Cooperative Relaying

Lossy decode-and-forward (DF) relaying, also referred to as lossy forwarding (LF), can significantly enhance the transmission reliability and expand the communication coverage at the cost of a small increase in computational effort compared to its DF counterpart. Furthermore, it can further simplify the operations at the relay nodes by removing the error-detecting operation, e.g., cyclic redundancy check, which is used in the conventional DF systems. Due to these advantages, LF has been intensively investigated with the aim of its applications to various cooperative communication networks with different topologies. This paper offers a comprehensive literature review on the LF relaying strategy and makes comparisons between LF and DF. Five basic exemplifying scenarios are taken into consideration. These are the three-node network, the single-source multi-relay network with direct source-to-destination link, the multiple access relay channel, the two-way relay network, and the general multi-source multi-relay network. The paper includes not only theoretical performance limit analyses, but also performance evaluation by employing low-complexity accumulator aided turbo codes at the sources and relays as well as joint decoding at the destination. As expected, the performance enhancement in terms of outage probability, frame error rate, and -outage achievable This work is supported in part by the EU-FP7 project ICT-619555 RESCUE (Links on-the-fly Technology for Robust, Efficient and Smart Communication in Unpredictable Environments), in part by Academy of Finland network compression based wireless cooperative communication systems (NETCOBRA, No. 268209) project, in part by Academy of Finland 6Genesis Flagship (grant 318927), in part by Nokia Foundation, HPY Foundation, Oulu University Scholarship, Tauno Tönningin Foundation, and Riitta Ja Jorma J. Takanen Foundation Sr., in part by the State Key Program of National Natural Science of China under Grant No. 61432002, in part by the National Natural Science Foundation of China Guangdong Joint Fund under Grant No. U1701263, in part by the National Natural Science Foundation of China under Grant No. 61702365, in part by the National Natural Science Foundation of China (NSFC), No. 61702011, in part by the Natural Science Foundation of Tianjin under Grant No. 17JCQNJC00700, in part by the Special Program of Artificial Intelligence of Tianjin Municipal Science and Technology Commission under Grant No. 17ZXRGGX00150, and also in part by JAIST Core-to-Core Program. J. He and M. Juntti are with the Centre for Wireless Communications, University of Oulu, Oulu, 90014, Finland (e-mail: {jiguang.he, markku.juntti}@oulu.fi). V. Tervo was with the Centre for Wireless Communications, University of Oulu, Oulu, 90014, Finland. He is now with Nokia, Mobile Networks, Oulu, Finland (e-mail: valtteri.tervo@nokia.com). X. Zhou is with the Tianjin Key Laboratory of Advanced Networking (TANK), School of Computer Science and Technology, Tianjin University, Tianjin 300350, China (e-mail: xiaobo.zhou@tju.edu.cn). X. He is with the School of Mathematics and Computer Science, Anhui Normal University, Anhui, China (e-mail: xin.he@ahnu.edu.cn). S. Qian and M. Cheng are with Japan Advanced Institute of Science and Technology, Ishikawa, 923-1292, Japan (e-mail:{shen.qian, mcheng}@jaist.ac.jp). T. Matsumoto is with the Centre for Wireless Communications, University of Oulu, Oulu, 90014, Finland, and Japan Advanced Institute of Science and Technology, Ishikawa, 923-1292, Japan (e-mail: matumoto@jaist.ac.jp). Manuscript received Month day, year; revised month day, year. rate by LF over DF is significant, which is demonstrated in all the exemplifying scenarios in the literatures. Hence LF has a great potential to be applied to future 5G wireless communication networks, e.g., device-to-device, vehicle-to-vehicle, and machinetype communications, which are composed of the aforementioned exemplifying scenarios.