MSc. Abstract
​
In the telephone network, the circuit between the subscriber's equipment and the local exchange is called the local loop. Wireless Local Loop (WLL) is the use of radio to make a connection from a local switch or a distribution point in the fixed network to a number of homes. WLL provides reliable, flexible, and economical access to the local telephone service using radio technology in the place of traditional wireline.
CDMA technology has the potential to provide a significant improvement in the capacity of cellular radio systems compared with FDMA and TDMA systems. However, this improvement is dependent upon the effectiveness of the power control system, especially on the reverse link.
In this research work, the reverse link capacity of CDMA WLL system is analytically derived, and the capacity gain achieved in a CDMA WLL over cellular mobile environment is calculated. The results show that, the capacity of both systems are largely affected by the other cell interference (i.e. number of active users in the surrounding cells). However, directional subscriber antennas deployed at WLL network reduce the other-cell interference, or equivalently increase the system capacity, where the CDMA WLL system can accommodate approximately 36% more users than CDMA cellular mobile system (when the surrounding cells are full).
This study also apply the synchronization approach to increase the reverse link capacity of the CDMA WLL system, which synchronizes the reverse link so that signals transmitted from different subscriber units within the same cell are time aligned at the base station (BS). A theoretical analysis of the potential capacity gain of reverse link synchronous CDMA WLL is presented.
Also the effect of both imperfect power control and imperfect sectorization on the performance of CDMA WLL systems is evaluated in this study. The results show that, the capacity degradation due to imperfect power control is about 25.8% and 11.5% for a single cell and multiple cell systems, respectively. Increasing the overlapping angle from 00 to 50 causes the capacity gain to decrease from 6 to 5.53, while the corresponding sectorization efficiency drops from 100% to 92.3%.