Comparing with that of terrestrial networks, the location management in satellite networks is mainly restricted by three factors, i.e., the limited on-board processing (OBP), insufficient link resources and long propagation delay. Under these restrictions, the limited OBP can be smoothened by terrestrial gateway-based location management, the constraint from link resources demands the bandwidth-efficient management scheme and long propagation delay potentially lowers the management efficiency. Currently, the reduction of the management cost has always been the main direction in existing work which is based on the centralized management architecture. This centralized management has many defects, such as the non-optimal routing, scalability problem and single point of failure. To address these problems, this paper explores gateway-based distributed location management schemes for Low Earth Orbit (LEO) satellite networks. Three management schemes based on terrestrial gateways are proposed and analyzed: loose location management, precise location management, and the grouping location management. The analyses specifically analyze the cost of location queries and show their significant influence on the total cost which includes the location management and query. Starting from the above analysis, we speculate and prove the existence of the optimum scheme in grouping location management, which has the lowest total cost for the query frequency within given range. Simulation results validate the theoretical analysis on the cost and show the feature of latency in location queries, which provide a valuable insight into the design of the distributed location management scheme in satellite networks.

In group location management, when a transportation system (TS) with mobile stations (MSs) changes location area (LA), only a single group location update by the TS is needed, instead of multiple individual location updates by MSs riding on the TS. Therefore, group location management significantly reduces location update signaling of the current individual location management. In this paper, we further improve the conventional group location management, by paging cells containing the route of public TS within an LA only, if an incoming call arrives at an MS riding on the TS, based on the observation that public TS, such as bus, subway, and train, follows a fixed route; its movement is not random. The performance of the proposed scheme is analyzed in terms of total signaling cost based on the modeling of public TS route. Numerical results reveal that the proposed scheme significantly outperforms the conventional scheme from the aspect of total signaling cost, at the expense of small network overhead due to the additional queries needed to acquire public TS route information.

Although a lot of works for location management in wireless networks have been reported in the literature, most of the works have been focused on designing per-user-based strategies. This means that they can achieve the performance enhancement only for a certain class of mobile users with a specific range of CMR (call-to-mobility ratio). However, these per-user-based strategies can actually degrade the performance if a user's CMR changes significantly. Therefore, an efficient uniform location management strategy, which can be commonly applied to all mobile users regardless of their CMR, is proposed and analyzed in this paper. The motivation behind the proposed strategy is to exploit the concepts of the two well-known existing strategies: the location caching strategy and the local anchor strategy. That is, the location caching strategy exploits locality in a user's calling pattern, whereas the local anchor strategy exploits locality in a user's mobility pattern. By exploiting these characteristics of both strategies together with the profile management at the HLR (home location register), the proposed strategy can reduce the frequent access to the HLR, and thus effectively results in significant reduction in terms of the total location management cost. The analytical results also demonstrate that the proposed strategy can be uniformly applied to all mobile users, while always maintaining the performance gain over the IS-41 standard regardless of a user's CMR and the network traffic conditions.

A dynamic anchor-area (DAA) scheme is proposed to reduce the location management cost for PCS networks. Based on an Intra-LA location update (LU) scheme, the proposed DAA scheme utilizes a given timer value and a movement list. The DAA scheme considers a wider variety of mobile terminal's movement pattern than the previous intra-LA LU scheme. Simulations confirm that the proposed scheme offers a significant reduction in the location management cost.

The default server strategy is commonly used to manage the location and state of mobile hosts in cellular networks. With this strategy, connections can be established after the client obtains the location information of the mobile host by querying the default server. Unfortunately, the communication cost increases if the query requests are frequent and the distance between the default server and the client is long. Still more, no connection to a mobile host can be established when the default server of the destination mobile host fails. These problems can be solved by replicating the default servers and by letting the nearest replicated default server process the query request which is sent from a client [9]. It is important to allocate replicated default servers efficiently in networks and determine the number of replicated default servers. In this paper, we suggest and evaluate a default server replication strategy to reduce communication costs and to improve service availabilities. We consider optimal replication degree as well as location for replicating the default servers in n-grid and tree networks.

A novel distributed dynamic regional location management scheme called MORR (Mobility Oriented Regional Registration) is proposed for Mobile IP to improve the signaling traffic cost of a mobile node. This improvement is achieved by adjusting each mobile node's optimal regional domains according to its mobility behavior. With Mobile IP, the capricious mobility and variable traffic load of a mobile node has an impact on its average signaling traffic cost. In this paper, the mobility of all mobile nodes is classified into two modes: random mobility mode and regular mobility mode. We develop new analytical models to formulate the movement behavior and mathematically evaluate their characteristics when applied to these two modes. MORR has the adaptability to manipulate various mobility modes of each mobile node in dedicated ways to determine an optimal regional domain of this mobile node. Simulation results show that anywhere from 3 to 15 percent of the signaling cost is saved by MORR in comparison with the previous distributed dynamic location management schemes for various scenarios.

In mobile communication systems, mobility tracking operations are executed to maintain known the whereabouts of each mobile terminal (MT). In this article, we propose and analyse two new versions of the original time-based registration method, namely the Stop and Wait (S W) and the Reset and Wait (R W) time-based strategies. We also propose and study the modified S&W and R&W schemes as a result of combining the S&W and R&W policies with the enhanced time-based method in [3]. When the MT uses one of the four schemes proposed, it sends less location update (LU) messages. As a result of fewer LUs, which results in less contacts with the network, the uncertainty of the MT position increases in the proposed time-based schemes. Although the MT paging (PG) cost is lightly increased, a significant reduction in the LU cost is achieved. As it is shown, the net effect is a saving in the total location management cost per call arrival. In order to analyse the four strategies and compare them with the original and enhanced time-based schemes, a performance evaluation method based on Markovian standard tools is proposed here. The location management cost for all these time-based policies are evaluated analytically here by using this evaluation method.

This letter proposes an improved timer-based location management scheme for packet-switched (PS) mobile communication systems. Compared to the conventional timer-based scheme with a single timer threshold, a new timer-based scheme with two timer thresholds is proposed to accommodate the bursty data traffic characteristics of PS service. The location update and paging costs of the proposed scheme are analyzed and compared with those of the conventional scheme. We show that the proposed scheme outperforms the conventional scheme in terms of total cost of both location update and paging with an appropriate selection of timer thresholds.

Over the last decade there has been a rapid growth of wireless communication technology. Among numerous wireless network architectures, the personal communication services (PCS) networks and wireless local area networks (WLAN) have attracted lots of attention. One of the core functionalities in wireless networks is the location service that provides location information for subscriber services, emergency services, and various mobile networks internal operations. In this paper, an integrated location management mechanism is proposed for heterogeneous wireless networks that combine PCS networks and WLAN. Three major functionalities in the integrated location management scheme are the determination of the WLAN connectivity for a mobile terminal, the development of a local area location scheme for WLAN, and the location prediction module for PCS networks. This mechanism not only determines the location of a mobile client more precisely, but also reduces the cost of locating. The performance evaluation is conducted to demonstrate the effectiveness of the proposed mechanism for heterogeneous wireless networks.

Future personal communication service (PCS) networks consider smaller cells to accommodate continuously growing population of subscribers. That results in frequent location update and consequently higher signaling cost. Among various schemes proposed for improving the efficiency of location management, the distance-based and the direction-based location update methods work well for just certain mobility patterns. In this paper, we propose a hybrid location update (HLU) scheme, which takes into account both the moving distance and the moving direction when deciding on updating the location. We analyze the performance of the HLU under different mobility patterns and call-to-mobility ratios based on a 2D Markov walk model. The numerical results demonstrate that the HLU scheme can achieve better performance than the distance-based or the direction-based methods applied individually.

Mobile IP provides an efficient and scalable mechanism for host mobility within the Internet. Using Mobile IP, mobile nodes may change their point of attachment to the Internet without changing their IP address. In contrast to the advantages of Mobile IP, updating the location of a mobile node incurs high signaling costs if the mobile node moves frequently. Thus, IP paging schemes for Mobile IP have been proposed to avoid unnecessary registration signaling overhead when a mobile node is idle. However, they require the additional paging costs and delays associated with message delivery when a correspondent node sends packets to the idle mobile node. These delays greatly influence the quality of service (QoS) for multimedia services. Moreover, existing IP paging schemes do not consider a hierarchical mobility management scheme, which can reduce signaling costs by the significant geographic locality in user mobility pattern. Thus, we propose a novel IP paging protocol which can be used in hierarchical Mobile IPv6 networks. In addition, our proposal can reduce signaling costs for paging and delay using the concept of the anchor-cell. The cost analysis presented in this paper shows that our proposal has superior performance when the session-to-mobility ratio value of the mobile node is low.

In this paper, we consider a location management scheme using Limited Pointer forwarding from Commonly visited sites (LPC) strategy for Personal Communication Services (PCS) networks. The Commonly Visited Site (CVS) is defined as a site in which a mobile user is found with high probability. A feature of the strategy is that it skips updating location information of the mobile user, provided that the mobile user moves within its CVSs. Such a strategy is expected to significantly reduce the location update cost. We evaluate the location management cost of the LPC scheme by employing a Continuous-Time Markov Chain (CTMC) model. We show that the LPC scheme can reduce the location management cost of a highly mobile user who is found in its CVS with high probability.

The exciting goals of ubiquitous computing and communication services can only be achieved if we can increase the efficiency with which the location of mobile terminals can be managed; current mobile infrastructures are not efficient since they treat all mobile terminals uniformly despite that fact that many mobiles often move together (i.e. passengers on the same train or a group of cars on a road). This paper presents a hierarchical location management scheme that handles such grouped mobiles collectively and so reduces the overhead costs of location management. In our scheme, mobiles that move together for long enough form a mobile network and make a hierarchy in the wireless access network. The scheme also adjusts the number of mobile networks to keep communication overhead low. We apply the scheme to Mobile IPv6 and evaluate the resulting performance improvement. Simulation results confirm that our hierarchical approach can greatly reduce the overhead costs of location management, and that it is very practical since it can flexibly develop suitable mobile networks.

In this letter, we propose an enhanced time-based registration method and analyze the performance numerically. In the analysis, we assume Poisson call arrival distribution and exponential cell resident time. The performance of the enhanced time-based registration method is compared with the performance of the original time-based registration method. In the comparisons, we see that in a certain range of parameters, the enhanced time-based registration method has better performance.

In this paper, we propose a new predictive location management strategy that reduces the update cost while restricting the paging load optimized for mobiles roaming with traceable patterns. Enhanced with directional predictive capabilities offered by Kalman filtering, new update boundaries are assigned to better reflect the movement patterns of individual mobiles upon location registration. Thus, while complying with the required delay constraints, QoS measures such as throughput will not need to be sacrificed as a result of increasing update threshold. The contribution of this paper is two-fold: (1) to propose a distribution model that is capable of describing a wide range of movement patterns with varying correlation between traveling directions and (2) to show the capabilities (in terms of reliable performances) of the Kalman filter in predicting future movement patterns. Simulation results have successfully demonstrated the ability of the Kalman filter in assigning update boundaries capable of reflecting a mobile's roaming characteristics. The performance gains achieved mainly through a significant reduction in the number of updates indicate its potential for promoting better bandwidth conservation.

Intelligent paging uses the sequential paging technique with additional user information in order to reduce the paging delay cost and the paging load cost. Our proposed paging scheme uses distribution density information of users as required additional user information. This letter addresses an optimal paging sequence and introduces formulas to calculate the paging costs. These formulas are necessary to evaluate the performance of location management. The paging delay cost and the paging load cost for the proposed paging scheme and two other paging schemes are calculated and numerical analyses for these paging schemes are performed. Results show how the paging delay cost and the paging load cost vary as either the paging request arrival rates or the number of cells in an LA increases. The proposed paging scheme is more efficient in view of both the paging delay cost and the paging load cost.

An improved movement-based registration scheme reduces location update cost on conventional movement-based location update scheme but increases uncertainty of the position of a mobile terminal (MT). The effect of this uncertainty of the MT position on the paging cost of the improved movement-based registration scheme is analyzed. We show that the paging cost of the improved movement-based registration scheme in [2] is underestimated, especially for large values of movement threshold. The result shows that the underestimation cannot be ignored.

It is very important to accurately and effectively track the movement of each mobile terminal in the personal communications networks. Accordingly, various dynamic location update schemes reflecting the mobile terminal's moving pattern are proposed in the literature. Important schemes include time-based, movement-based, distance-based, and direction-based location update schemes. In this paper, we intend to improve the performance of the movement-based location update scheme which is simple to implement and shows good performance. The proposed location update scheme reflects each mobile terminal's movement characteristics and reduces the number of unnecessary location updates. The performance of the proposed scheme is evaluated and compared with the previously proposed movement-based location update scheme through simulation. The proposed location update scheme requires three memory elements to maintain the movement history in the mobile terminal. The simulation results show that the location management cost is significantly reduced especially for the case with small call-to-mobility ratio by minimizing the unnecessary location updates intrinsic in the movement-based location update scheme.

We propose Concatenated Location Management (CLM), utilizing tendency for mobile terminals (MTs) to move as a group. When many MTs are on the same train, for example, they move together and share the same mobility characteristics. Therefore, we propose to concatenate the MTs and link them to the train for more efficient location management. CLM can reduce the number of location management signals because the train sends only one location registration signal on behalf of all of the individual MTs when a location registration area boundary is crossed. We discuss the key functions for CLM including location registration, paging, and location register configuration.

Wireless mobile communication networks support mobile terminals (MTs) which are free to travel within a service coverage area. In order to locate an MT effectively when a call is initiated, several location management schemes are proposed to keep track of its location. Current methods being used in IS-41 and GSM MAP for location management pose problems such as an increase in signaling traffic in the network, a ping-pong effect and a bottleneck created by signaling traffic at home location register (HLR). In this paper, we propose a new location management scheme that is to reduce the number of location registrations at HLR by making the location registration at HLR unnecessary when an MT moves into neighboring registration area (RA) or when it moves back to the original RA from neighboring RA. Our scheme employs a centralized database architecture using the HLR/VLR concept as in the IS-41 and GSM MAP but alleviates the above-mentioned problems. Analysis results show that our scheme always outperforms current methods and shows an especially better performance at low CMR (call to mobility ratio).