Two-way relay is potentially an effective approach to spectrum sharing and aggregation by allowing simultaneous bidirectional transmissions between source-destinations pairs. This paper studies the two-way 2×2×2 relay network, a class of four-unicast networks, where there are four source/destination nodes and two relay nodes, with each source sending a message to its destination. We show that w...

We give a comprehensive discussion on coding techniques for the primitive relay channel, in which the channel input X is transmitted to the relay Y1 and the ultimate receiver Y over a channel p(y, y1|x) and the relay can facilitate the communication between the transmitter and the receiver by sending some information to the receiver over a separate noiseless link of capacity R0. In particular, ...

This paper studies upper bounds and lower bounds on the outage capacity and ergodic capacity of a three-node wireless relay channel in a Rayleigh fading environment. We also take into account practical constraints on the transmission duplexing at the relay node and on the synchronization between the source node and the relay node. We find that the gap between the upper bounds and lower bounds i...

A simple technique to secure quantum key distribution relay networks is presented here. The paper introduces the concept of logical channels that uses a random dropout scheme. The paper also presents an enhanced protocol for key distribution in the relay networks. Previous techniques relied on creating distinct physical paths to create shares. Hence the compromise of one relay must compromise t...

Consider an unstable linear time invariant system in which the sensor transmits information to a controller across an additive white Gaussian noise channel. The designer can optionally utilize a relay node to assist the controller; however the total transmission power consumed by the sensor and the relay node is constant. We consider two topologies: (i) a Gaussian relay channel, and (ii) a casc...

We proposed a new physical layer technique that can enhance the security of cooperative relay communications. The proposed approach modifies the decoded message at the relay according to the unique channel state between the relay and the destination such that the destination can utilize the modified message to its advantage while the eavesdropper cannot. We present a practical method for secure...

In modern transmission networks, relay plays an important role for cooperative strategies. Several relaying strategies, such as decode-forward, compress-forward and amplify-forward, have been proposed for relay channels and networks. However, the capacity for the general relay channel and network is still unknown. In this thesis, we propose several relay schemes for different relay models. In t...

Zero-error communication over a primitive relay channel is for the first time proposed and studied. This model is used to highlight how one may exploit the channel structure to design a relaying strategy that explicitly provides “what destination needs”. We propose the Colour-and-Forward relaying scheme which constructs a graph GR of relay outputs based on the joint conditional distribution of ...

This work concerns minimizing the achievable distortion of a Gaussian source over a two-hop block fading channel under mean square-error criterion. It is assumed that there is not a direct link between transmission ends and the communication is carried out through the use of a relay, employing the Decode and Forward (DF) strategy. Moreover, for both of transmitter-to-relay and relay-to-destinat...