abstract—in this paper, the problem of secure transmission in two-hop amplify-and-forward (af) systems with an untrusted relay is investigated. to prevent the untrusted relay from intercepting the source message and to achieve positive secrecy rate, the destination-based cooperative jamming (dbcj) technique is used. in this method the destination sends an intended jamming signal to the relay. t...

We propose novel cooperative protocols for various coherent flat-fading channels composed of half-duplex nodes. We consider relay, cooperative broadcast (CB), multiple-access relay (MAR) and cooperative multiple-access (CMA) channels and devise efficient protocols for them. We also present automatic repeat request (ARQ) variants of these protocols. We evaluate the proposed protocols using the d...

This paper analyzes the performance of a dualhop amplify-and-forward (AF) cooperative relay network in the presence of direct link between the source and destination and multiple co-channel interferences (CCIs) at the relay. Specifically, we derive the new analytical expressions for the moment generating function (MGF) of the output signal-to-interference-plus-noise ratio (SINR) and the average...

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...

Relay networks have recently attracted extensive attention due to its potential to increase coverage area and channel capacity. In a relay network, a source node communicates with a destination node with the help of the relay node. The performances of improving the channel capacity and coverage area have been explored and evaluated in the literature (Sendonaris et al., 2003)-(Laneman et al., 20...

Cooperative diversity networks have recently been proposed as a promising technology to improve performance over fading channels. In this paper, we consider incremental amplify-and-forward (AF) cooperative diversity networks which employ the Nth best relay when the best relay is unavailable due to issues such as scheduling or load balancing. The end-to-end performance is analyzed over independe...

We investigate the performance of adaptive decode-forward (ADF), amplify-forward (AF), and hybrid decode-amplify-forward (HDAF) relaying protocol. Specifically, we derive the closed-form expression of symbol error probability (SEP) for these three relaying protocols. For the AF protocol, we derive a simpler and more tractable final result than previously published work. Furthermore, analyzing t...

Abstract—In this paper, the problem of secure transmission in two-hop amplify-and-forward (AF) systems with an untrusted relay is investigated. To prevent the untrusted relay from intercepting the source message and to achieve positive secrecy rate, the destination-based cooperative jamming (DBCJ) technique is used. In this method the destination sends an intended jamming signal to the relay. T...

In amplify-and-forward (AF) two-way relay networks, information is exchanged between two source nodes via a relay node by AF relaying. This dissertation develops the blind detection designs for various two-way relay systems such as one antenna AF two-way relay network with direct link, one antenna AF two-way relay network without direct link, and multiple antenna AF two-way relay network withou...

Recently, the idea of space-time coding has been applied to wireless relay networks wherein a set of geographically separated relay nodes cooperate to process the received signal from the source and forward them to the destination such that the signal received at the destination appears like a Space-Time Block Code (STBC). Such STBCs (referred to as Distributed SpaceTime Block Codes (DSTBCs)) w...