Summary
International Symposium on Antennas and Propagation
2010
Session Number:3TF4
Session:
Number:3TF4-3
Performance Evaluation of Primary-Secondary Transmission in Actual Indoor Environments
Tomoki MURAKAMI, Riichi KUDO, Takeo ICHIKAWA, Masato MIZOGUCHI,
pp.-
Publication Date:2010/11/23
Online ISSN:2188-5079
Summary:
By the spread of wireless LAN systems, a lot of access points (APs) are set up in various places such as residence and office etc. The increase of the number of APs causes the inter-cell interference (ICI). In WLAN systems, the ICI can be mitigated by Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA) using Carrier Sense Multiple Access / Collision Avoidance (CSMA/CA). However, system capacity is not increased because of limited frequency and time resources. The issue of the ICI is being argued as the OBSS (Overlapping Basic Service Set) issue in IEEE802.11ac and 11aa [1]. To dramatically increase system capacity in the overlapping cell environment, we focused on beamforming techniques using array antenna [2]. Because spatial domain resource can increase in proportion to the number of antennas, increase of system capacity is expected As spatial domain resource sharing, either centralized [3] or decentralized [4], [5] approaches have been proposed. Although centralized approaches are able to achieve higher system capacity, all APs must be synchronized and share all of the transmission data and the channel state information (CSI). Decentralized approaches increase the system capacity by using the CSI for stations (STAs) that communicate with the other AP. While they offer less system capacity increase than centralized approach, they are more suitable for WLAN systems because the APs that different owners have are less likely to cooperate with each other. Paper of [5] proposed the primary-secondary (PS) transmission scheme on the basis of the decentralized approach and this scheme attains the high achievable bit rate in an overlapping cell environment by virtual wall. In this paper, we show performance evaluation of the PS transmission using the CSI measured in an actual overlapping cell environment. In the PS transmission, the primary AP and secondary AP communicate with their own destination STAs, and the ICI from the secondary cell on the primary cell is mitigated by beamforming of the secondary AP while the primary AP works as it would in an isolated cell. To evaluate this scheme performance in actual overlapping cells, we measured the 8×4 channel matrices of MIMO-OFDM signals in an indoor apartment environment. The results show that this scheme can increase system capacity for horizontal and vertical cell orientations. Moreover, evaluations of this scheme in both cell orientations show that the effectiveness of this scheme can be estimated by just the interference to noise ratio (INR).