Modeling and Optimizing IEEE 802.11 DCF for Long-Distance Links
This paper explores the feasibility of designing an outdoor cellular network based on the IEEE 802.11 standard, which was developed originally for wireless localarea networks. Specifically, the performance of the 802.11 radio and multiple access control (MAC) protocol in outdoor environments is investigated. For channels typical in cellular networks, we study the radio link power budget and the bit-error performance of three kinds of receivers. We also propose a new timing structure for the MAC protocol to handle increased signal propagation delay, and analyze its throughput performance in the outdoor network. Our analysis shows that the MAC protocol can handle a cell radius of 6 km without violating the 802.11 standard. However, the link budget reveals that the maximum cell radius in an outdoor 802.11 network ranges from 0.4 to 1.2 km, about one-third that supported by W-CDMA and EDGE networks. For an rms delay spread of 1 s μ , typical for urban-area cells of this size, our simulation results show that the conventional RAKE receiver can yield a satisfactory performance. Combining these results, we conclude that using ordinary equipment, an 802.11-based cellular network with a cell radius up to 1.2 km is feasible. It is possible to further extend the service range by advanced techniques such as smart antennas. Index terms Communication system performance, IEEE standards, multi-access communication, multipath channels, radio communication, spread spectrum communication, wireless LAN.