There are two principal aspects of "mobility" in location-aware computing: (1) how to support mobility and (2) how to exploit it. This paper considers the latter, while many existing works only concentrate on the former. This work is trying to prove that the performance of location-aware systems will be greatly improved by understanding the user's movement. In this paper, we propose a novel location update protocol called state-based location update protocol (SLUP), which significantly minimizes the energy consumption of mobile client by exploiting a syntactic information of a user's movement. This concept is called mobility-awareness which is a kind of context-awareness. Moreover, there are three variations of the proposed protocol in terms of how to choose the optimal state: SLUP/BS, SLUP/UITR, and SLUP/IUT. Experimental results show that the proposed protocol outperforms the well-known existing protocols such as dead-reckoning and distance-based protocol, and that the SLUP/IUT approach can achieve different performance tradeoffs between energy efficiency and location accuracy by fine-tuning its algorithmic parameter Tiut.

This paper presents a novel analytical approach to evaluate the signaling load of Mobile IPv6 (MIPv6) and Hierarchical Mobile IPv6 (HMIPv6). Previous analytical approaches for IP mobility management have not provided a complete and general framework for the performance analysis; no consideration of either periodic binding refresh cost or extra packet tunneling cost from the viewpoint of IP mobility management, and no in-depth investigation with respect to various system parameters. In this paper, according to the proposed analytical approach, we derive the location update costs (i.e., the sum of binding update costs and binding refresh costs), packet tunneling costs, inside-domain signaling costs, outside-domain signaling costs, and total signaling costs, which are generated by a mobile node (MN) during its average domain residence time in case MIPv6 or HMIPv6 is deployed under the same network architecture, respectively. Moreover, based on these derived costs, we evaluate the impacts of various system parameters on the signaling costs generated by an MN in MIPv6 and HMIPv6. The aim of this paper is not to determine which protocol performs better, but evaluate the performance that can be expected for each protocol under the various conditions, broaden our deep understanding of the various parameters that may influence the performance, and provide insight for the deployment of the two protocols.