Cost-Optimal QoS Aggregation for Network Mobility

Abstract

Many existing communication protocols fail to perform efficiently when groups of users move in unison and at high velocity. A classic example is the Mobile IP protocol, which, as it stands, leads to storms of binding updates at every IP handover, but is resolved by the NEMO basic support protocol. However, a problem of similar nature is also existent in Quality of Service protocols, which again tend to produce signalling storms at handover, leading to, somewhat paradoxically, surges of congestion within the access network. While QoS aggregation improves protocol scalability by maintaining a single QoS state for potentially the entire moving network rather than for each individual node, the act of having to constantly maintain this state when sessions are frequently created and terminated undermines its benefit. We therefore propose a dynamic cost-driven QoS aggregation policy, which aims at minimising network operator costs for each aggregation cycle. Simulations of the cost-driven policy show that costs are reduced by up to 6.5% relative to other QoS aggregation policies, with expected user waiting times prior to session establishment increasing by a only a fraction of a second.