A throughput/delay comparison: narrowband vs. broadband wireless LANs

The authors consider a communication system in which a large number of portable notebooks access a centrally located base station by means of a shared, high-speed radio-based local area network. The dominant impairment to high-speed radio networking in such an environment is frequency-selective multipath fading. They compare the delay and throughput performances of two approaches: one high-speed channel shared by all portable remotes vs. several moderate-speed channels each shared by a subset of portable units. In both cases, access to the intended services is impeded by contention for the medium and queuing for some shared server. Both systems are modeled as closed queuing networks, and expressions for system throughput and average request delay are obtained. Numerical results show that a wide range of parameters, the system containing one high-speed channel outperforms the system containing several parallel medium-speed channels by less than 10%