Ergodic Capacity Analysis of Multiple Input Multiple Output Systems with Dual Hop Amplify and Forward Relay Networks

Abstract

Problem Statement: In MIMO system, capacity mainly depends on the channel and the antenna characteristics. The capacity can be improved by proper design of antenna elements and choosing appropriate array configuration and the directive elements give more capacity than omni directional elements. The dual polarized antennas are better than single polarized antennas as the former can provide two information channels. The mutual coupling also changes the capacity considerably. When the spacing between the elements is less than 0.5λ, the effect of mutual coupling is more. Approach: This study analyzes the capacity of Echelon, H-shaped; V-shaped free standing dipoles and printed dipole arrays of a MIMO system. The channel model for multi-polarized antennas is used in the simulations. The mutual coupling between the dipoles of different orientations is also included to make simulation more realistic. MIMO system with relay network is used to improve the coverage and reliability and to reduce the interference in wireless network. So we have analyzed the characterization of the ergodic capacity of amplify-and-forward (AF) MIMO dual-hop relay channels, assuming that the channel state information is available at the destination terminal only. Results: This study presents the results for channel capacity for different antenna configuration and the exact Ergodic capacity, closed form expression for the high SNR regime and tight closed form upper and lower bounds for amplify and forward relay system using the probability density function of an unordered eigenvalues. Conclusion/Recommendations: The Echelon, H-shaped; V-shaped free standing dipoles offer better capacity results in conventional MIMO system. The results produced are valid for all SNR values and for arbitrary numbers of antennas at the source, relay and destination. We also demonstrate a relationship between the conventional point-to-point MIMO Channels and dual-hop AF MIMO relay channel.