Relay selection is an attractive method to improve the bandwidth efficiency of cooperative networks [1]-[3]. Specifically, Bletsas and others [1] proposed a distributed relay selection based on the channel information of both the first and second hops for each relay, showing that the diversitymultiplexing tradeoff of relay selection is identical with that of distributed space-time coding. Recen...

—In this paper the outage-optimal relay deployment problem for amplify-and-forward (AF) multi-input multi-output (MIMO) two-way relaying network with antenna selection is studied. By utilizing an approximation of the outage probability, the outage-optimal relay location is shown feasible. On this basis a relay deployment scheme is developed by providing the near-optimal relay position in an ap...

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...

Most works on amplify and forward (AF) relaying assume that the relay obtains perfect channel state information (CSI) of the source-relay channel. This renders variable-gain relaying (VGR) an attractive technique, as the relay can ideally invert the channel at its input and thus ensure constant output power. What happens to the output power, however, if the CSI at the input is outdated? As an a...

In this paper, we derive the exact symbol error probability (SEP) of cooperative systems using amplify and forward (AF) relaying and partial relay selectionwhen the different links are independent and non-identically distributed. In conventional relay selection, the selected relay offers the best instantaneous signal to noise ratio (SNR) of the relaying link (source-relay-destination). However,...

In this paper, we study the interference relay-without-delay channel which is an interference channel with a relay helping the communication. We assume the relay’s transmit symbol depends not only on its past received symbols but also on its current received symbol, which is an appropriate model for studying amplify-and-forward type relaying when the overall delay spread is much smaller than th...

In this paper, we investigate a joint source and relay precoding design scheme for an amplify-and-forward (AF) multiple-input multiple-output (MIMO) relay system with absence of the direct link. The joint optimization problem, which is to minimize an objective function based on the mean square error (MSE), is formulated as a nonconvex optimization problem in the AF MIMO relay system. Instead of...

Abstract— In this paper, we propose a direct/cooperative amplify-and-forward relay (D/AR) switching using a spectrum division/adaptive subcarrier allocation (SDASA) for increasing the uplink capacity of single carrier-frequency division multiple access (SC-FDMA). In the D/AR switching, switching between direct communication and cooperative AF relay is done so that the channel capacity is maximi...