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

Abstract

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.

Indexing terms:

• Capacity
• Radio interference
• Dynamic channel selection
• Wireless local loop
• Sectoral antennas
• Non Poisson traffic model

Additional information

Notes on contributors

Vijayalakshmi Chetlapalli

Vijayalakshmi Chetlapalli graduated in Electronics and Communications Engineering from Jawaharlal Nehru Technological University in 1994. She received her MS in Communications from the Indian Institute of Technology,-Madras in 1998. From October 1998 to December 2000, she was Senior Project Officer in the Department of Electrical Engineering, IIT Madras during which she worked on the development of an RF planning tool for the corDECT WLL system. Her work as a Senior Development Engineer in Midas Communication Technologies Pvt Ltd during December 2000-July 2002 included the development of a Remote Monitoring tool for performance analysis and early fault detection of corDECT Base Stations and WallSets, besides various performance studies on the corDECT network. Since August 2002, she is with the Center of Excellence (Network Design and Engineering), Mahindra British Telecom, Pune working on the development of a tool for planning CDMA networks.

Devendra Jalihal

Devendra Jalihal obtained BTech (Hons) from the Indian Institute of Technology, Kharagpur in 1983, MEngg from McMaster University, Hamilton, Canada in 1988 and Ph D from Duke University, Durham, USA in 1992, all in Electrical Engineering,

From 1983 to 1986 he was with Engineers India Ltd., New Delhi. From 1986 to 1992, he was Research Assistant first at McMaster University and later at Duke University. He did post-doctoral work at Duke University from 1992 to 1994. He has been with the Electrical Engineering Department, NT Madras since 1994 where he is presently Associate Professor.

His present research interests include applications of digital signal processing to communication and real-time voice and video communication on packet switched networks. He is a member of the TeNeT group, IIT Madras which is involved in the development of telecom products.