We consider relay channels in which the source-destination and relay-destination signals are assumed to be orthogonal and thus have to be recombined at the destination. Assuming memoryless signals at the destination and relay, we propose a low-complexity quantize-and-forward (QF) relaying scheme, which exploits the knowledge of the SNRs of the source-relay and relay-destination channels. Both i...

Cooperative communications is a new wireless communication technique which allows single antenna mobiles to share their antennas and to produce virtual multiple antenna system. We investigate the impact of relay location on the SER and system capacity for multi relay (amplify and forward) cooperative network in terms of distance and obtained the best relay location analytically. The impact of r...

In a wireless transmission network, relay node or intermediate nodes play a very important role. Thus, the use of relay transmission offers significant performance benefits, including being able to achieve spatial diversity through node cooperation and extending coverage without requiring large transmitter powers. In this paper, we consider a Physical-layer Network Coding (PNC) scheme for a two...

An amplify-and-forward (AF) wireless relay network consisting of a one-source-one-destination node pair and cooperative multiple N relay nodes is proposed in three adverse wireless communication environments, i.e., jamming, node geometry, and channel uncertainty. Based on the minimum mean square error (MMSE) criterion, the optimal amplifying relay matrix in three adverse wireless environments w...

The two-way amplify-and-forward (AF) relaying network consisting of 2M sources with only a single antenna per source and one relay with multiple N antennas at the 2M destinations is investigated in this paper. All sources act as both sources and destinations with a self-interference cancelation process at the 2M destinations. The closed form of the relay amplifying matrix is optimized under the...

—To improve the problems of noise amplification and error propagation of the fixed cooperation schemes in cooperative communications, a relay selection strategy is proposed based on the hybrid decode-amplify-forward protocol. It can adaptively determine cooperation schemes according to the Channel Status Information (CSI) of the source-relay. Then it selects the best relay from the candidate r...

The authors investigate the performance of amplify-and-forward relaying with two different pilotsymbol-assisted channel estimation methods. In the first estimation method, the cascaded channel consisting of source-to-relay and relay-to-destination links is estimated at the destination terminal. No channel estimator is required at the relay terminal. In the second estimation method, the estimati...

We consider communication protocols for N -way all-cast relay networks, which comprise N source terminals such that each source terminal demands messages from all other source terminals with the help of a relay. The derived protocols are characterized by the fact that physical layer network coding is employed at the relay, where each source has side information about the signals it has sent. Am...

In this paper, Hybrid relay systems are comprised of Amplify-andForward (AF), Decode-and-Forward (DF) and DeModulate-and-Forward (DMF) together in cooperative networks. We propose adaptive relay schemes based on Channel State Information (CSI) of the received Signal-to-Noise Ratio (SNR) at the Relay Node (RN). We select the relay protocol adaptively, on the basis of Power Allocation (PA) constr...