Mobile wireless networks pose interesting challenges for routing system design. To produce feasible routes in a mobile wireless network, a routing system must be able to accommodate roving users, changing network topology, and fluctuating link quality. We discuss the impact of node mobility and wireless communication on routing system design, and we survey the set of techniques employed in or proposed for routing in mobile wireless networks.

In current distributed systems, the notion of mobility is emerging in many forms and applications.

This paper describes current and proposed protocols for mobility management for public land mobile network (PLMN)-based networks, mobile Internet protocol (IP), wireless asynchronous transfer mode (ATM), and satellite networks. The integration of these networks will be discussed in the context of the next evolutionary step of wireless communication networks. First, a review is provided of location management algorithms for personal communication systems (PCS) implemented over a PLMN network. The latest protocol changes for location registration and handoff are investigated for Mobile IP, followed by a discussion of proposed protocols for wireless ATM and satellite networks. Finally, an outline of open problems to be addressed by the next generation of wireless network service is discussed

Mobile computing has the potential for managing information globally. Data management issues in...

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In personal communications applications, users communicate via wireless with a wireline network. The wireline network tracks the current location of the user, and can therefore route messages to a user regardless of the user’s location. In addition to its impact on signaling within the wireline network, mobility tracking requires the expenditure of wireless resources as well, including the power consumption of the portable units carried by the users and the radio bandwidth used for registration and paging. Ideally, the mobility tracking scheme used for each user should depend on the user’s call and mobility pattern, so that the standard approach, in which all cells in a registration area are paged when a call arrives, may be wasteful of wireless resources. In order to conserve these resources, the network must have the capability to page selectively within a registration area, and the user must announce his or her location more frequently. In this paper, we propose and analyze a simple model that captures this additional flexibility. Dynamic programming is used to determine an optimal announcing strategy for each user. Numerical results for a simple one-dimensional mobility model show that the optimal scheme may provide significant savings when compared to the standard approach even when the latter is optimized by suitably choosing the registration area size on a per-user basis. Ongoing research includes computing numerical results for more complicated mobility models and determining how existing system designs might be modified to incorporate our approach. I.

Abstract—This paper introduces a dynamic hierarchical database architecture for location management in personal communications service (PCS) networks. The proposed scheme allows the dynamic adjustments of user location information distribution based on the mobility and calling patterns of the mobile terminals (MT’s). A unique distribution strategy is determined for each MT, and location pointers are set up at selected remote locations which indicate the current location of the MT’s. This method effectively reduces the signaling and database access overhead for location registration and call delivery. Besides, the required processing is handled by a distributed network of directory registers and centralized coordination is not necessary. The functions of the other network elements, such as the home location register (HLR) and the visitor location registers (VLR’s), remain primarily unchanged. This greatly facilitates the deployment of this scheme in current PCS networks. Index Terms—Call delivery, directory register, home location register (HLR), location registration, visitor location register (VLR). I.

We consider per-user profile replication as a mechanism for faster location lookup of mobile users in a Personal Communications Service system. We present a minimum-cost maximum-flow based algorithm to compute the set of sites at which a user profile should be replicated given known calling and user mobility patterns. We then present schemes for replication plans that gracefully adapt to changes in the calling and mobility patterns. We show the costs and benefits of our replication algorithm against previous location lookup approaches through analysis. We also simulate our algorithm against other location lookup algorithms on a realistic model of a geographical area to evaluate critical system performance measures. A notable aspect of our simulations is that we use well-validated models of user calling and mobility patterns. 1 Introduction In a Personal Communications Service (PCS) system, users place and receive calls through a wireless medium. Calls may deliver voice, data, text, fa...

Mobile internetworking revolves around the premise that a mobile host (MH) will frequently attach to and detach from the Internet, thus changing its address frequently. Location management in mobile internetworking refers to the process of keeping track of the current addresses of MHs in the Internet. Protocols proposed for mobile internetworking rely on a combination of searches and updates for location management. A drawback of these protocols is that they are not uniformly efficient over all possible call-to-mobility ratios (i.e., the relative frequency of searches as compared to updates) . An important issue, therefore, is how the overall costs of location management can be reduced, regardless of the call-to-mobility ratio. The aim of this work is to explore a new and practical scheme for location management, with emphasis on network cost reduction.

To accommodate the increase in user population in future personal communication systems, hierarchical architectures of location databases have been proposed. In this paper, a scheme based on forwarding pointers is presented, that reduces the cost of the overall network and database traffic generated by frequent location updates in such hierarchical architectures. To reduce the number of forwarding pointers that need to be traversed to locate a user, auxiliary caching techniques are presented. Various conditions for purging the chain of forwarding pointers and updating the database are also introduced. Special care is given so that the scheme correctly supports the concurrent execution of updates and lookups. The applicability of the scheme and the performance of the caching techniques are demonstrated through a number of experiments for a range of call to mobility ratios and for a variety of moving and calling behaviors. Keywords: Mobile Computing, Distributed Database Systems, Locati...