In this thesis, a suite of schemes is presented to enhance the performance of cooperative communication networks. In particular, techniques to improve the outage probability, end-to-end delay and throughput performances are presented. Firstly, a buffer-aided cooperative communication is studied and analyzed for packet selection and relay selection. A three-node network is considered in the beginning and the phenomenon of packet diversity is taken into consideration to overcome bad channel conditions of the
source to relay (SR) and relay to destination (RD) links. The closed-form expressions for the computation of the outage probability along with the delay, throughput and diversity gain are derived. Then, packet selection is studied along with relay selection for buffer-aided amplify and forward (AF) cooperative relaying networks. The proposed protocol is analyzed for both symmetric and asymmetric channel conditions and buffer size using multiple antennas at relays and compared against the existing buffer-aided schemes.
Markov chain (MC) is used to derive the closed-form expressions for outage probability, diversity gain, delay and throughput.
Next, the performance of SNR based hybrid decode-amplify-forward relaying protocol is observed. When SR link is the strongest, data is transmitted to the selected relay and checked against the predefined threshold at the relay. If it is greater than the threshold, data is decoded and stored in the corresponding buffer. Otherwise, it is amplified and stored in the respective buffer. When RD link is the strongest, data is transmitted to the destination. MC based theoretical framework is used to derive an expression for the outage probability, the average end-to-end delay and throughput. Then, relay selection schemes considering the instantaneous link quality along with buffer status in the relay selection are proposed. A scheme is proposed that simultaneously considers buffer status and link quality. Then, we discuss multiple links with equal weights using a general relay selection factor. It includes the weight of the link as the first metric and the link quality, or priority, as the second metric for different cases of the same weight. The proposed scheme is evaluated for symmetric and asymmetric channel conditions.
Moreover, we propose a specific parameter, termed as the bu�er-limit, which controls the selection of SR or RD links and also have its impact on the average delay and throughput. In this scheme, the outage probability is traded with the average end-to-end queuing delay or the average throughput by adjusting the values of the buffer-limit. The MC based framework is employed to derive the closed-form expressions for the outage probability, average end-to-end queuing delay and the average throughput. The suggested schemes are compared to the existing bufferaided relay selection schemes.
Lastly, we consider the energy constraint cooperative network and propose a generalized approach to study the performance of energy harvesting relaying schemes.
The unified modeling of generalized energy harvesting relaying (GEHR) scheme covers the non-energy harvesting schemes and the well-known energy harvesting schemes, i.e., time switching based relaying (TSR) and power splitting based relaying (PSR). Moreover, the scheme also caters the hybrid of both TSR and PSR schemes. The closed-form expressions for the outage probability and ergodic capacity and average throughput are formulated for non-mixed Rayleigh fading and mixed Rayleigh-Rician fading channels. Each case is analyzed for AF and decode and forward relaying models. Comprehensive Monte-Carlo simulations confirm all theoretical results.