CelluLAN: A Microcellular Network of Spread-Spectrum Wireless LANs with Efficient Spectral Reuse

Abstract

The wireless network introduced here, called "CelluLAN," can be used as both wireless local area network (LAN) and as a microcellular network. This is achieved by providing the capability of efficient spectral reuse. This capability became possible by spread-spectrum methods that allow the rejection of interference from adjacent CelluLANs. Spread-spectrum also enhances the multiple access throughput by utilizing its delay capture properties. In particular, we have presented the spread-spectrum random access (SSRA) and the spread-spectrum digital sense multiple access (SS-DSMA), which are based on the media access control (MAC) layer protocols of slotted Aloha and DSMA, respectively. These protocols are then enhanced with the capability of "joint delay and power capture" which is provided at the physical layer. Performance analysis of the system has been carried out to provide the throughput and the uncoded bit error rate of the SSRA and SS-DSMA protocols. The performance analysis is based on a detailed evaluation of the interference power between adjacent CelluLANs or frequency bands in a fully loaded network and with different types of pulse shaping filter. Performance results indicate that the CelluLAN network has satisfactory throughput performance with SS-DSMA protocol and when frequency reuse is one. As shown, the throughput performance is improved significantly when we use the joint delay-power capture technique. We also show that when the spreading factor increases above the point at which the frequency bands overlap, the access throughput begins to decrease.