On-demand QoS routing in multihop mobile networks

The emergence of nomadic applications have recently generated a lot of interest in next generation wireless network infrastructures (e.g., the 3G EGPRS (Enhanced General Packet Radio Services), UMTS/IMT-2000, etc.) which provide differentiated service classes. So it is important to study how the Quality of Sen ice (QoS), such as packet loss and bandwidth, should be guaranteed. To accomplish this, we develop an admission control scheme which can guarantee bandwidth for real-time applications in multihop mobile networks. In our scheme, a host need not discover and maintain any information of the network resources status on the routes to another host until a connection request is generated for the communication between the two hosts, unless the former host is offering its services as an intermediate forwarding station to maintain connectivity between two other hosts. This bandwidth guarantee feature is important for a mobile network (e.g., wireless LAN, EGPRS, etc.) to interconnect wired networks with QoS support (e.g., ATM, Internet, etc.). Our connection admission control scheme can also work in a stand-alone mobile ad hoc network for real-time applications. This control scheme contains end-to-end bandwidth calculation and bandwidth allocation. Under such a scheme, the source (or the ATM gateway, or Enhanced Serving GPRS Supporting Node) is informed of the bandwidth and QoS available to any destination in the mobile network. This knowledge enables the establishment of QoS connections within the mobile network and the efficient support of real time applications. In case of ATM interconnection, the bandwidth information can be used to carry out intelligent handoff between ATM gateways and/or to extend the ATM virtual circuit service to the mobile network with possible renegotiation of QoS parameters at the gateway (e.g., Enhanced Gateway GPRS Supporting Node). We examine via simulation the system performance in various QoS traffic flows and mobility environments. Simulation results suggest distinct performance advantages of our protocol calculating the bandwidth information. Furthermore, "on-demand" feature enhances the performance in the mobile environment because the source can keep more connectivity with enough bandwidth to a receiver in the path-finding duration. Simulation experiments show this improvement.