MIMO Channel Capacity and Configuration Selection for Switched Parasitic Antennas

Abstract

Multiple‐input multiple‐output (MIMO) systems offer significant enhancements in terms of their data rate and channel capacity compared to traditional systems. However, correlation degrades the system performance and imposes practical limits on the number of antennas that can be incorporated into portable wireless devices. The use of switched parasitic antennas (SPAs) is a possible solution, especially where it is difficult to obtain sufficient signal decorrelation by conventional means. The covariance matrix represents the correlation present in the propagation channel, and has significant impact on the MIMO channel capacity. The results of this work demonstrate a significant improvement in the MIMO channel capacity by using SPA with the knowledge of the covariance matrix for all pattern configurations. By employing the “water‐pouring algorithm” to modify the covariance matrix, the channel capacity is significantly improved compared to traditional systems, which spread transmit power uniformly across all the antennas. A condition number is also proposed as a selection metric to select the optimal pattern configuration for MIMO‐SPAs.

λ/64‐spaced compact ESPAR antenna via analog RF switches for a single RF chain MIMO system

“…In order to solve the disadvantages, analog spatial multiplexing techniques via a parasitic array antenna with a single RF chain were developed [10][11][12][13][14][15]. We examined a λ/16 spacing single RF Chain MIMO antenna by using low power CMOS switches [10].…”

Passive parasitic UWB antenna capable of switched beam‐forming in the WLAN frequency band using an optimal reactance load algorithm

“…However, their use is limited owing to the use of multipole antenna elements, a narrow bandwidth, expensive phase shifters and attenuators, the increased complexity, and the overall system size. To cover the commercial frequency band and increase the gain of the desired frequency band, it is necessary to develop a small single antenna technology that combines a UWB antenna with the beam‐forming circuit technology.…”