Power Allocation and Cooperative Diversity in Two-Way Non-Regenerative Cognitive Radio Networks

In this paper, we investigate the performance of a dual-hop block fading cognitive radio network with underlay spectrum sharing over independent but not necessarily identically distributed (i.n.i.d.) Nakagami-$m$ fading channels. The primary network consists of a source and a destination. Depending on whether the secondary network which consists of two source nodes have a single relay for cooperation or multiple relays thereby employs opportunistic relay selection for cooperation and whether the two source nodes suffer from the primary users' (PU) interference, two cases are considered in this paper, which are referred to as Scenario (a) and Scenario (b), respectively. For the considered underlay spectrum sharing, the transmit power constraint of the proposed system is adjusted by interference limit on the primary network and the interference imposed by primary user (PU). The developed new analysis obtains new analytical results for the outage capacity (OC) and average symbol error probability (ASEP). In particular, for Scenario (a), tight lower bounds on the OC and ASEP of the secondary network are derived in closed-form. In addition, a closed from expression for the end-to-end OC of Scenario (a) is achieved. With regards to Scenario (b), a tight lower bound on the OC of the secondary network is derived in closed-form. All analytical results are corroborated using Monte Carlo simulation method

Performance analysis of cooperative relay networks in presence of interference

In the past decade, cooperative communication has emerged as an attractive technique for overcoming the shortcomings of point-to-point wireless communications systems. Cooperative relaying improves the performance of wireless networks by forming an array of multiple independent virtual sources transmitting the same information as the source node. In addition, when relays are deployed near the edge of the network, they can provide additional coverage in network dead spots. Interference in the network can also be reduced in cooperative communications systems as the nodes can transmit at lower power levels compared to equivalent point-to-point communications systems. Optimum design of a cooperative network requires an accurate understanding of all factors affecting performance. In order to parameterize the performance of cooperative systems, this thesis introduces mathematical models for different performance metrics, such as symbol error probability, outage probability and random coding error exponent, in order to analytically estimate network capacity. A dual-hop network is introduced as the most basic type of relay network. Random coding error exponent results have been obtained using this simple network model are presented along with corresponding channel capacity estimates based on the assumption of Gaussian input codes. Next, a general multihop network error and outage performance model are developed. Detailed mathematical and statistical models for interference relay networks are presented. The basic statistical parameters, cumulative distribution function and probability density function for interference cooperative dual hop relay networks are derived and explored. A partial formulation for the random coding error exponent (RCEE) result is also presented. Simulation results over Rayleigh and Nakagami-m fading channel models are included in each chapter for all of the selected performance metrics in order to validate the theoretical analysis, under the assumption that channels are flat over the duration of one symbol transmission. These results are in close agreement with the predictions of the analytical models.University of Technology, Sydney. Faculty of Engineering and Information Technology

Outage Probability Analysis of Dual Hop Relay Networks in Presence of Interference

Cooperative relaying improves the performance of wireless networks by forming a network of multiple independent virtual sources transmitting the same information as the source node. However, interference induced in the network reduces the performance of cooperative communications. In this work the statistical properties, the cumulative distribution function (CDF) and the probability density function (PDF) for a basic dual hop cooperative relay network with an arbitrary number of interferers over Rayleigh fading channels are derived. Two system models are considered: in the first system model, the interferers are only at the relay node; and in the second system model, interferers are both at the relay and the destination. This work is further extended to Nakagami-m faded interfering channels. Simulation results are presented on outage probability performance to verify the theoretical analysis