Outdoor IEEE 802.11 cellular networks: radio link performance

We explore the feasibility of designing an outdoor cellular network based on the IEEE 802.11 standard, which was developed originally for wireless local-area networks. For channels typical in cellular networks, we study the radio link power budget and, via simulation, the bit-error performance of three kinds of receiver: (1) the constrained RAKE, which is limited to a 1 μs multipath span; (2) the full RAKE, which uses the full multipath channel information; (3) the ideal equalizer, the performance of which is represented by the matched filter bound. Our link budget reveals that the maximum cell radius in an outdoor 802.11 network ranges from 0.7 to 3 km, about half that supported by WCDMA and EDGE networks. For an RMS delay spread of 1 μs, typical for urban-area cells of this size, our simulation results show that the conventional constrained RAKE receiver may yield a satisfactory performance. The improved receivers, however, yield 1-5 dB gain over the constrained implementation. Combining these results with those in a companion paper on the MAC protocol (see Leung, K.K. et al., ibid., p.595-599), we conclude that an 802.11 based cellular network with a cell radius of a few km is feasible