Impact of Mutual Coupling on Adaptive Switching Between MIMO Transmission Strategies and Antenna Configurations

Abstract

Adaptive switching between multiple-input multiple-output (MIMO) transmission strategies like diversity and spatial multiplexing is a flexible approach to respond to channel variations. It is desirable to obtain accurate estimates of the switching points between these transmission schemes to realize the capacity gains made possible by adaptive switching. In this paper, it is shown that the accuracy of switching point estimates for switching between statistical beamforming and spatial multiplexing is improved by taking into account the effects of mutual coupling between antenna array elements. The impact of mutual coupling on the ergodic capacities of these two transmission strategies is analyzed, by deriving expressions for the same. Adaptive switching between combinations of transmission strategies and antenna array configurations (using reconfigurable antenna arrays) is shown to produce maximum capacity gains. Expressions for the switching points between transmission strategies and/or antenna configurations, including mutual coupling effects, are derived and used to explore the influence of mutual coupling on the estimates. Finally, measurements taken from reconfigurable rectangular patch antenna arrays are used to validate the analytical results.

Throughput-based mode switching for MIMO ARQ systems in presence of transmit correlation

“…In the conventional mode switching algorithms [8][9][10][11][12], the successive rate transmission (SRT) and ideal CAC are assumed. However, in the practical systems, in order to reduce the payload of the control channel, the DRT is indicated by the MCS level.…”

“…In recent years, practical adaptive algorithms to the MIMO switching were extensively studied [8][9][10][11][12]. The algorithm described in [8] used the minimum Euclidean distance, which can be used to determine the bit error rate, to switch between different modes when the instantaneous channel knowledge is known.…”

“…Reference [9] derived the ergodic capacity expression for each MIMO transmission scheme in the spatially correlated channel, and proposed the mode switching based on the upper bound of the capacity. Some other capacity-based mode switching schemes were also proposed in [10][11][12].…”

Reduction of Mutual Coupling and Return Loss in Microstrip Array Antennas Using Concave Rectangular Patches

“…When one array element radiates, a portion of its radiated power is absorbed by other elements and induces current on them. The mutual coupling effect leads to problems such as beam forming error, scanning error, and input power wastage [7][8][9]. Therefore, the effect of mutual coupling must be reduced in array antenna design.…”

“…To calculate the radiation pattern of an array the mutual coupling effect must be considered. Without considering this effect, large errors in beam forming and null string are resulted [7,8]. To decrease the mutual coupling effect, several methods such as changing feed position and feed structure and replacing ordinary patches with new types, such as fractal patches, have been reported [9][10][11][12][13][14].…”