Joint Relay Selection and Analog Network Coding using Differential Modulation in Two-Way Relay Channels

In this paper, we consider a general bi-directional relay network with two sources and N relays when neither the source nodes nor the relays know the channel state information (CSI). A joint relay selection and analog network coding using differential modulation (RS-ANC-DM) is proposed. In the proposed scheme, the two sources employ differential modulations and transmit the differential modulated symbols to all relays at the same time. The signals received at the relay is a superposition of two transmitted symbols, which we call the analog network coded symbols. Then a single relay which has minimum sum SER is selected out of N relays to forward the ANC signals to both sources. To facilitate the selection process, in this paper we also propose a simple sub-optimal Min-Max criterion for relay selection, where a single relay which minimizes the maximum SER of two source nodes is selected. Simulation results show that the proposed Min-Max selection has almost the same performance as the optimal selection, but is much simpler. The performance of the proposed RS-ANC-DM scheme is analyzed, and a simple asymptotic SER expression is derived. The analytical results are verified through simulations.Comment: 20 pages, 7 figure

The SER Analysis of Rayleigh, Rician and Nakagami Channels at Various Relay Locations in Cooperative Networks

Reliable communication between transmitter and receiver is accomplished by cooperative diversity techniques. Sending of data in various paths has greatly improved the performance of communication. We have studied the performance of Amplify-and-Forward (AF) based network in this work for diverse relay location at Nakagami, Rician and Rayleigh fading channels. The relay performance in Amplify-and-Forward (AF) protocol based on Symbol Error Rate (SER) against Signal-to-Noise Ratio (SNR) in dBs is calculated. The software that is used to construct Monte-Carlo link level simulation is MATLAB. The effects of a relay at changed location in diverse channels accompanied with Additive White Gaussian noise (AWGN) is also calculated. BPSK modulation scheme is used for the transfer of information between the source, relay and destination node. The signals are combined through Maximum Ratio Combining method (MRC).Reliable communication between transmitter and receiver is accomplished by cooperative diversity techniques. Sending of data in various paths have greatly improved the performance of communication. We have studied the performance of Amplify-and-Forward (AF) based network in this work for diverse relay location at Nakagami, Rician and Rayleigh fading channels. The relay performance in Amplify-and-Forward (AF) protocol based on Symbol Error Rate (SER) against Signal-to-Noise Ratio (SNR) in dBs is calculated. The software that is used to construct Monte-Carlo link level simulation is MATLAB. The effects of relay at changed location in diverse channels accompanied with Additive White Gaussian noise (AWGN) is also calculated. BPSK modulation scheme is used for the transfer of information between the source, relay and destination node. The signals are combined through Maximum Ratio Combining method (MRC)

Sparse multiple relay selection for network beamforming with individual power constraints using semidefinite relaxation

This paper deals with the multiple relay selection problem in two-hop wireless cooperative networks with individual power constraints at the relays. In particular, it addresses the problem of selecting the best subset of K cooperative nodes and their corresponding beamforming weights so that the signal-to-noise ratio (SNR) is maximized at the destination. This problem is computationally demanding and requires an exhaustive search over all the possible combinations. In order to reduce the complexity, a new suboptimal method is proposed. This technique exhibits a near-optimal performance with a computational burden that is far less than the one needed in the combinatorial search. The proposed method is based on the use of the l1-norm squared and the Charnes-Cooper transformation and naturally leads to a semidefinite programming relaxation with an affordable computational cost. Contrary to other approaches in the literature, the technique exposed herein is based on the knowledge of the second-order statistics of the channels and the relays are not limited to cooperate with full power.Peer ReviewedPostprint (author's final draft

Selective Combining for Hybrid Cooperative Networks

In this study, we consider the selective combining in hybrid cooperative networks (SCHCNs scheme) with one source node, one destination node and $N$ relay nodes. In the SCHCN scheme, each relay first adaptively chooses between amplify-and-forward protocol and decode-and-forward protocol on a per frame basis by examining the error-detecting code result, and $N_c$ ($1\leq N_c \leq N$) relays will be selected to forward their received signals to the destination. We first develop a signal-to-noise ratio (SNR) threshold-based frame error rate (FER) approximation model. Then, the theoretical FER expressions for the SCHCN scheme are derived by utilizing the proposed SNR threshold-based FER approximation model. The analytical FER expressions are validated through simulation results.Comment: 27 pages, 8 figures, IET Communications, 201

Relay Selection for Two-way Relaying with Amplify-and-Forward Protocols

In this paper, we propose a relay selection amplify-and-forward (RS-AF) protocol in general bi-directional relay networks with two sources and $N$ relays. In the proposed scheme, the two sources first transmit to all the relays simultaneously, and then a single relay with a minimum sum symbol error rate (SER) will be selected to broadcast the received signals back to both sources. To facilitate the selection process, we propose a simple sub-optimal Min-Max criterion for relay selection, where a single relay which minimizes the maximum SER of two source nodes will be selected. Simulation results show that the proposed Min-Max selection has almost the same performance as the optimal selection with lower complexity. We also present a simple asymptotic SER expression and make comparison with the conventional all-participate amplify-and-forward (AP-AF) relaying scheme. The analytical results are verified through simulations. To improve the system performance, optimum power allocation (OPA) between the sources and the relay is determined based on the asymptotic SER. Simulation results indicate that the proposed RS-AF scheme with OPA yields considerable performance improvement over an equal power allocation (EPA) scheme, specially with large number of relay nodes.Comment: 19 pages, 6 figure