Multiuser cooperative communication significantly improves the performance of wireless communication networks. One key challenge of multiuser cooperative communication is how to design a cooperative mechanism to incentivize potential relay nodes to help a source node in its data transmission. In this paper, to address this problem, we apply a contract-based principal-agent framework to a cognit...

Most sensornetworkarchitectures typically assume thatnodes are stationary after deployment. However, a number of recent papers have shown that theuseofmobilenodesormobiledata collectors (MDC)can significantly improve the performance of a network. In thismodel, the network can be viewed as a three-tier architecture, where the lowest-tier consists of a set of sensor nodes. Themiddle-tier contains...

The use of fountain codes in wireless cooperative relay networks can improve the system performance in aspects such as transmission time, energy consumption, transmission efficiency and outage probability etc. This has been proved when the number of the relay nodes and their relaying capabilities are stationary. But in practical networks the relay nodes are variable and dynamic. This paper prop...

This paper studies performance of two-hop relay system operating in Ricean fading environment. Implementation of a dual-polarized antenna at the receiver node is assumed, as a solution for enhancing the system energy efficiency. First, we analytically examine the level of performance improvement for decode-and-forward (DF) relay systems, in terms of bit error rate (BER), accomplished just by ca...

In this paper, we study the physical layer security (PLS) problem in the dual hop orthogonal frequency division multiplexing (OFDM) based wireless communication system. First we consider a single user single relay system and study a joint power optimization problem at the source and relay subject to individual power constraint at the two nodes. The aim is to maximize the end to end secrecy rate...

To provide for reliability in Wireless Sensor Networks (WSNs), Medium Access Control (MAC) protocols must be adapted by mechanisms taking cross-layer approaches into account. In this article, after introducing existing MAC protocols, we describe AreaCast, our protocol, which is designed for enhancing reliability in WSNs. AreaCast is a MAC layer protocol independent of the routing layer, but use...

Robust Beamforming for OFDM Modulated Two-Way MIMO Relay Network. (May 2012) Jianwei Zhou, B.S., University of Hawaii at Manoa Chair of Advisory Committee: Shuguang Cui This thesis studies a two-way relay network (TWRN), which consists of two single antenna source nodes and a multi-antenna relay node. The source nodes exchange information via the assistance of the relay node in the middle. The ...

Optimized Link State Routing (OLSR) is a in a popular proactive routing protocol for providing peer-to-peer transmissions in mobile ad hoc networks (MANETs). Since sensitive data are communicated in MANET, security remains a major issue. In this paper, we propose a trust based Multipoint Relay (MPR) selection algorithm for defending a specific type of denial-of-service (DOS) attack called node ...

—It is known that one of the essential building blocks of distributed turbo codes is the interleaver and its design uses random, semi-random (S-Random) and deterministic permutations. In this paper, a new modified matched S-random interleaver for turbo code is proposed. Then we extend the effect of this new interleaver to the relay channel to evaluate the interleaving gain in two different dis...

Relay selection has been regarded as an effective method to improve the performance of cooperative communication system. However, frequent operation of relay selection can bring enormous control message overhead and thereby decrease the performance of cooperative communication. To reduce the relay selection frequency, in this paper, we propose a relay selection scheme to choose the best relay w...