This paper investigates security-oriented beamforming designs in a relay network composed of a source-destination pair, multiple relays, and a passive eavesdropper. Unlike most of the earlier works, we assume that only statistical information of the relay-eavesdropper channels is known to the relays. We propose beamforming solutions for amplify-and-forward (AF) and decode-and-forward (DF) relay...

This paper focuses on a joint relay-selection and resource-allocation algorithm for an Amplify-andForward (AF) cooperative network. In a multiuser scenario, joint relay selection and power allocation is a combinational problem for heterogeneous, i.e., real time (RT) and non-real time (NRT), users. In single relay AF (S-AF) scheme, a source-destination pair selects best relay. Thus only two chan...

Cooperative relaying is one of the promising technology which is used to improve coverage and spatial diversity. A new relay strategy, the N Best-Relay Selection scheme is proposed to improve the bandwidth penalty and to increase the spatial diversity by using a sub-optimal allocation for the relay relative distance between the source and destination in a multi-hop cooperative systems. A single...

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...

In this paper, we investigate the secrecy outage probability (SOP) for the cooperative amplify-and-forward (AF) two-way relay networks (TWRN) with channel estimation (CE) errors under Rayleigh fading channels. In the proposed system, two sources simultaneously broadcast their respective information to all the relays firstly. Then, the optimal relay performs AF protocol on the received signals s...

Wireless relay networks have been studied extensively in the recent literature. Amplify and forward (AF) is one of the most widely used type of relaying. Even though special cases such as channel-noise-assisted, channel-assisted and blind relay modes have been analyzed, a unified performance analysis seems to be not available. In this paper, we present unified performance analysis results for t...

—Two-way amplify-and-forward (AF) relaying networks have been widely studied because of its simplicity and high spectral efficiency. In this paper, we investigate the relay selection problem and the diversity-multiplexing tradeoff (DMT) for two-way AF relaying systems over independent flat Rayleigh fading channels. We first derive the closed-form expression of the minimum total transmit power ...

In this paper, we investigate the antenna and node selection issues for amplify-and-forward (AF) and decode-and-forward (DF) multi-antenna relay networks in correlated channels. Based on the channel statistics, optimal selection criteria for antenna and relay node are derived jointly, aiming to maximize the ergodic capacity. Instantaneous channel knowledge-based selection schemes, motivated by ...

In this paper, we consider two-way orthogonal frequency division multiplexing (OFDM) relay channels, where the direct link between the two terminal nodes is too weak to be used for data transmission. The widely known per-subcarrier decode-and-forward (DF) relay strategy, treats each subcarrier as a separate channel, and performs independent channel coding over each subcarrier. We show that this...