Hot-spot congestion relief in public-area wireless networks

Wireless LAN administrators are often called upon to deal with the problem of sporadic user congestion at certain popular spaces ("hot-spots") within the network. To address this problem, we describe and evaluate two new approaches, explicit channel switching and network-directed roaming for providing hot-spot congestion relief while maintaining pre-negotiated user bandwidth agreements with the network. The goals of these algorithms are: (i) to accommodate more users by dynamically providing capacity where it is needed, when it is needed; (ii) to improve overall network utilization by making more efficient use of deployed resources; and (iii) to guarantee at least a minimum amount of bandwidth to users. We propose that both the network and its users should explicitly and cooperatively adapt themselves to changing load conditions depending on their geographic location within the network. We describe how these algorithms enable the network to transparently adapt to user demands and balance load across its access points (APs). We evaluate the effectiveness of these algorithms on improving user service rates and network utilization using simulations. Our algorithms improve the degree of load balance in the system by over 30%, and user bandwidth allocation by up to 52% in comparison to existing schemes that offer little or no load balancing.