Summary
International Symposium on Antennas and Propagation
2009
Session Number:1D1
Session:
Number:1D1-5
Effects of Path Visibility on Urban MIMO Systems
Sirichai Hemrungrote, Toshikazu Hori, Mitoshi Fujimoto, Kentaro Nishimori,
pp.157-160
Publication Date:2009/10/21
Online ISSN:2188-5079
Summary:
It has been concluded in many researches that MIMO wireless communication architecture promises an approach to achieve high bandwidth efficiencies [1], [2]. MIMO wireless channels can be simply defined as a link for which both transmitting and receiving ends equipped with multiple antenna elements. This advanced communication technology has potential to improve the channel capacity for the future networks. However, the performance of MIMO wireless communication has been considered that it strongly depends on the propagation environment [3]. In outdoor wireless communication, the propagation environment becomes very complex because the antenna heights among the surrounding buildings and the building height distribution itself in each urban area are different. The signal paths, especially the Line-of-Sight (LoS) between the base station (BS) antenna and the mobile terminal (MT), yield to change according to city environments [3]. Hence, we introduce a ray-tracing simulation method (EEM-RTM), in order to evaluate the channel capacity in urban MIMO systems. This method can be used for estimation of various propagation characteristics such as complex electric field, delay and angular profiles of emission/arrival of radio waves, etc. The simulation based on this method with various sets of parameters can discriminate the effects of urban model configurations as well as the antenna configurations over the actual experiment. Generally, the channel capacity in MIMO channel can be represented by the SNR and the spatial correlation. However, since these propagation parameters are largely affected by the antenna heights of the BS and the surrounding buildings, it was very difficult to simply explain the relationship between the channel capacity and these propagation parameters. Hence, a new parameter "path visibility" which means a measure whether the direct path can be received at the BS when considering the uplink scenario, is introduced herein. Although it is clear that there is relationship between the SNR and the path visibility in Single-Input Single-Output (SISO) channel, the MIMO channel capacity is affected by not only the SNR but also the spatial correlation. In this study, the relationships between the SNR, the channel capacity and the spatial correlation characteristics of urban MIMO systems and the path visibility are evaluated. Analysis model for urban propagation model, distribution of building height and width and channel capacity calculation is described in Sec. 2. Effects of path visibility on the SNR, channel capacity and spatial correlation are then discussed in Sec. 3. In Sec. 4, the contribution of this paper is concluded.