Capacity of High Density Macro Cellular Wireless Local Loop System based on Dynamic Channel Selection

Wireless Local Loop (WLL) is emerging as a cost effective alternative to the copper local loop to cater to the increasing demand for telecom services in densely populated urban areas in developing countries. While the wired local loop system provides a line dedicated to each subscriber, the wireless local loop has an additional limitation associated with the sharing of limited radio channels. Further, due to the limited bandwidth provided, the available frequency channels have to be reused, causing radio interference which limits the capacity of the system. In this paper, the traffic that can be handled by a fixed Wireless Local Loop system employing Dynamic Channel Selection has been evaluated, taking into account the radio interference. The effect of three kinds of radio interference—cochannel, adjacent channel and intermodulation—on the capacity of the system has been studied. Two kinds of antenna deployment strategies, omni-directional and sectoral, have been considered in the study. With omni-directional antennas, the capacity of the system was found to be interference limited. We show that the use of directional (sectoring) antennas at the base station overcomes the interference limitation and serves a higher subscriber density. The DECT standard has been assumed for the air interface in this study.