Performance analysis of MIMO dual hop AF relay networks over asymmetric fading channels
1University of Oulu, Faculty of Information Technology and Electrical Engineering, Department of Communications Engineering, Communications Engineering
|Online Access:||PDF Full Text (PDF, 1.4 MB)|
|Persistent link:|| http://urn.fi/URN:NBN:fi:oulu-201406061693
|Publish Date:|| 2014-06-10
|Thesis type:||Master's thesis (tech)
We analyze the performance of dual-hop multiple-input multiple-output (MIMO) amplify-and-forward (AF) relay systems by considering the source-to-relay and relay-to-destination channels undergo Rayleigh and Rician fading, respectively. Several MIMO techniques and practical relaying scenarios are considered to investigate the effect of such asymmetric fading on the MIMO AF relaying systems. First, we investigate the performance of the optimal single stream beamforming on non-coherent AF MIMO relaying. We use tools of finite-dimensional random matrix theory to statistically characterize the instantaneous signal-to-noise ratio (SNR). The closed-form expressions of the cumulative distribution function, probability density function, and moments of SNR are derived and used to analyze the performance of the system with outage probability, bit error rate (BER), and ergodic capacity. Numerical simulations are carried out to investigate the effects of the Rician factor, rank of the line-of-sight (LoS) component, and the number of antennas at the nodes on the system performance. Additionally, the performance is compared with orthogonal space-time block-coding (OSTBC) based AF MIMO system. Next, we investigate relay selection schemes for non-coherent dual-hop AF relaying with OSTBC over asymmetric fading channels. We propose two relay selection methods as optimal and sub-optimal schemes. The performance of proposed schemes are discussed with respect to the outage probability, BER and the ergodic capacity. Finally, we study the effect of co-channel interference (CCI) and feedback delay on the multi-antenna AF relaying over asymmetric fading channels. Here, transmit beamforming vector is calculated using outdated channel state information due to the feedback delay from relay-to-source, and the relay node experience CCI due to frequency reuse in the cellular network. The performance is investigated using the outage probability, BER and ergodic capacity to analyze the effect of the Rician factor, CCI, feedback delay and number of antennas. All these discussions are useful to evaluate the performance of AF MIMO systems in asymmetric fading channels. Our analysis suggests that having good LoS component increases the performance of the system for multiple-input-single-output (MISO) and single-input-multiple-output (SIMO) scenarios of relay-destination channel. Having good scattering component increases the performance for MIMO cases.