Performance of fixed and dynamic channel allocation schemes in a motorway environment

This paper aims to show the effects of road congestions arising from motorway roadworks on the performance of vehicular mobile networks. Using vehicular traces from loop Ids on a length of the M4 motorway in the UK, the impact of congestion due to speed control measures and lane closures in a section of the coverage area is simulated to show the resulting network effects on a fixed channel allocation (FCA) scheme. The performance of the system is then compared with a dynamic channel allocation (DCA) scheme to show how the load balancing nature of DCA mitigates the varying spatial distribution of traffic demand arising from road congestion. Furthermore the use of reservation slots to favour handoff requests is analysed for both FCA and DCA systems while considering a fixed and a dynamic number of slots reserved for handoff calls only. The considered area for the simulation consists of a linear array of five contiguous base stations in a cellular motorway network. The voice services considered use constant bit rate (CBR) data generation and have been modelled using a Poisson process with mean inter-arrival times and call duration periods generated for all vehicles independent of each other. The resulting degradation in the network performance in terms of blocked (call congestion) and dropped (handoff congestion) calls arising from the road congestion is evaluated.