Spectral-efficient And Trustworthy Successive Relaying Protocols Based On Network Interference Cancellation

Cooperative communication holds the promise of achieving spatial diversity gain for single-antenna users and enhancing transmission reliability.However,it suffers from low spectral efficiency due to the half-duplex constraint of relays.Successive relaying can effectively improve spectral efficiency in low cost and low complexity by using two half-duplex relays to mimic a full-duplex relay.But,it may cause severe inter-relay interference(IRI),reducing channel capacity and transmission reliability.Therefore,IRI cancellation becomes a key challenge for successive relaying.However,the existing IRI cancellation schemes have problems such as high complexity,high cost,or high privacy leakage risk.How to mitigate IRI with privacy protection in low complexity remains open.To solve the above problems,this work proposes the IRI suppression methods based on network interference cancellation,whose effectiveness is verified by theoretical analysis and numerical results.The main contributions of this work are summarized as follows:(1)This work proposes a successive relaying scheme based on analog network interference cancellation.To mitigate IRI,this scheme designs an IRI suppression method based on analog network interference cancellation and decode-and-forward(DF),where a relay actively keeps receiving signals from the source,which are then used as prior knowledge to enable an amplify-and-cancel(AC)IRI mitigation strategy.This scheme is capable of reducing the risk of privacy information leakage,because a relay does not need to know codebooks used by other relays and will not decode any signals intended for other relays.This work analyzes the minimum residual interference power,average throughput,outgate probability and optimal diversity-multiplexing tradeoff(DMT)of this successive relaying.Theoretical analysis and numerical results show that the proposed method outperforms conventional two-timeslot half-duplex relaying and existing successive relaying schemes.(2)This work proposes a successive relaying scheme based on mixed digital and analog network interference cancellation.Based on the conventional multi-relay cooperative communication model,this work presents a social-aware successive relaying for device-to-device(D2D)networks with mixed trustworthy and untrustworthy nodes.In particular,those trustworthy or untrustworthy nodes are distinguished based on the social connections of the source node.Furthermore,to maintain user privacy and information security,only those trustworthy nodes are allowed to decode signals received from the source,while those untrustworthy nodes are forbidden.As a result,the DF mode can be adopted by trustworthy nodes,however,untrustworthy nodes can only use the amplify-and-forward(AF)mode.Moreover,digital and analog signal process methods are applied to reduce the IRI incurred by successive relaying for those trustworthy and untrustworthy relays,respectively.This work analyzes and gives the average throughput,outage probability and maximum achievable diversity gain of the proposed scheme,and verifies the effectiveness of the proposed scheme through numerical simulation.This work studies the spectral-efficient and trustworthy successive relaying protocols based on network interference cancellation.To mitigate the IRI,this work presents an IRI suppression scheme based on analog network interference cancellation and an IRI suppression scheme based on mixed digital and analog network interference cancellation.By analyzing the average throughput,outage probability and DMT,the effectiveness of the proposed schemes is verified.