Movement-based Location Management Research Articles

Location distribution of a mobile terminal and its application to paging cost reduction and minimization

Reducing the cost of dynamic mobility management in wireless communication networks has been an interesting and important issue. It is well known that by using a selective paging method, both costs for location update and terminal paging can be reduced significantly. However, an efficient selective paging method needs the information of the location distribution of a mobile terminal. Based on our previous results on random walks among rings of cell structures, we analyze the location distribution of a mobile terminal in a paging area when a phone call arrives, where the inter-call time and the cell residence time can have arbitrary probability distributions. Our analysis is conducted for both distance-based and movement-based location management schemes, and for two different call handling models, i.e., the call plus location update model and the call without location update model. Together with our earlier results on location distribution in time-based location management schemes, for several selective paging methods, including progressive paging methods, ring paging methods, and cell paging methods, we are able to obtain their expected costs of paging for distance-based, movement-based, and time-based location management schemes. We find that a progressive paging method with very small time delay can reduce the terminal paging cost dramatically, while further increasing the time delay does not result in noticeable reduction of terminal paging cost. Our work reported in this paper significantly extends our understanding of cost reduction and minimization of dynamic location management in wireless communication networks.

Cost Analysis of Movement-Based Location Management in PCS Networks: An Embedded Markov Chain Approach

In this paper, we develop an approach of embedded Markov chain to analyze the signaling cost of a movement-based location management (MBLM) scheme. This approach distinguishes itself from those developed in the literature in the following aspects. 1) It considers the location area (LA) architecture used by personal communication service (PCS) networks for location management. 2) It considers two different call handling models that determine after a call whether a location update should be performed. 3) It considers the effect of the call holding time on the call handling models. 4) It proposes to use a fluid flow model to describe the dependence between the cell and the LA residence time. We derive closed-form analytical formulas for the signaling cost, whose accuracy is manifested by a simulation. Based on the analytical formulas, we conduct a numerical study to evaluate the influence of various parameters on the signaling cost. The formulas can contribute to the implementation of the MBLM scheme in PCS networks including Fourth-Generation (4G) Long-Term Evolution. The modeling approach developed in this paper can be exploited to model other location management schemes.

Modeling and performance analysis of an improved movement-based location management scheme for packet-switched mobile communication systems.

One of the key technologies to support mobility of mobile station (MS) in mobile communication systems is location management which consists of location update and paging. In this paper, an improved movement-based location management scheme with two movement thresholds is proposed, considering bursty data traffic characteristics of packet-switched (PS) services. The analytical modeling for location update and paging signaling loads of the proposed scheme is developed thoroughly and the performance of the proposed scheme is compared with that of the conventional scheme. We show that the proposed scheme outperforms the conventional scheme in terms of total signaling load with an appropriate selection of movement thresholds.

Cost analysis and minimization of movement-based location management schemes in wireless communication networks: a renewal process approach

The paper makes new contributions to cost analysis and minimization of movement-based location management schemes in wireless communication networks. The main contributions of the paper are three-fold. First, we consider two different call handling models, that is, the call plus location update (CPLU) model and the call without location update (CWLU) model. We point out that all existing analysis of location update cost of a movement-based location management scheme (MBLMS) do not accurately capture the essence of the two models. Second, we analyze the exact location update cost of an MBLMS under both CPLU and CWLU models using a renewal process approach which has rarely been used before. We find that the location update cost of an MBLMS under the CWLU model is much easier to analyze than that of an MBLMS under the CPLU model. Furthermore, an MBLMS operated under the CWLU model has lower location update cost than an MBLMS operated under the CPLU model. Third, we are able to derive a closed form solution to the movement threshold that minimizes the total cost of location management in an MBLMS for the CPLU model when the inter-call time has an arbitrary distribution and the cell residence time has an Erlang distribution, and for the CWLU model when both inter-call time and cell residence time have arbitrary distributions. Such closed form solutions have not been available in the existing literature.

Modeling and Cost Analysis of Movement-Based Location Management for PCS Networks With HLR/VLR Architecture, General Location Area and Cell Residence Time Distributions

Location management plays a central role in guaranteeing the effective operation of personal communication service (PCS) networks. In current PCS networks, a two-tier system of home location register (HLR) and visitor location register (VLR) databases is commonly used for location management. To improve the performance of PCS networks, several dynamic location management schemes have been proposed. Among the existing dynamic schemes, the movement-based location management may be the most practical due to its effectiveness and easy implementation under the framework of current PCS networks. To implement location management in PCS networks, cost analysis is a crucial aspect. However, most of the existing cost analyses for the movement-based scheme are too simple and not available for PCS networks with the HLR/VLR architecture. One reason for this is the complexity and the difficulty associated with the problem. Li et al. and Rodriguez-Dagnino et al. challenged this task by considering the HLR/VLR architecture. However, the cost analysis developed by Li et al. was carried out under the assumption that the cell and location area (LA) residence times are exponentially distributed. Rodriguez-Dagnino et al. furthered Li et al.'s work by assuming that the LA residence time follows a hyperexponential distribution and that the cell residence time is generally distributed. However, Li et al. and Rodriguez-Dagnino et al. failed to consider VLR location updates that are caused by terminal movements between LAs. In this paper, we relax the restrictions imposed on the distributions of the cell and LA residence times and propose an analytical model to study the movement-based scheme with HLR/VLR architecture. The issue of VLR location updates that are caused by movements between LAs is addressed carefully and successfully. Analytical formulas for the costs of HLR and VLR location updates are derived using a unified approach. Numerical study suggests that the total cost is a convex function of the movement threshold and is sensitive to the variances of the cell and LA residence times. The result presented in this paper can serve as a guideline for the system design and the implementation of the movement-based scheme for PCS networks.

Joint distribution of numbers of location updates and cell boundary crossings in movement-based location management schemes

The movement-based location management (LM) scheme is a well-known dynamic LM scheme that is relatively easy to implement. In this letter, we derive the joint probability distribution of the number of cell boundary crossings and number of location updates of a mobile terminal, assuming Poisson call arrivals and generally distributed cell residence time, under movement-based LM. The derived movement statistics are used to bound the movement threshold so that the number of location updates is kept within a reasonable range. Numerical results are presented.

Movement-Based Location Management for General Cell Residence Times in Wireless Networks

Location management of mobile users is of primary importance in personal communication networks (PCNs), and it is mainly aimed to facilitate the delivery of incoming calls to destination users and to make a more efficient use of network resources. In practical PCNs, the location management algorithms need to keep track of mobile users in a dynamic manner, and it is a design concern to minimize the generated signaling traffic. In this paper, we present the cost analysis for the dynamic movement-based location update scheme. Our model is based on renewal theory arguments, and it is general enough to include a variety of probability distributions for modeling cell residence times (CRTs) in hyperexponentially distributed location area residence times and exponentially distributed intercall times. We compare the location update cost for the dynamic and static schemes. We present numerical results regarding the exponential and circular CRT distributions and discuss the optimal threshold distance for location update that minimizes the cost of the dynamic movement-based scheme.

Optimization of Sequential Paging in Movement-Based Location Management Based on Movement Statistics

The movement-based scheme is a dynamic location management (LM) scheme that is particularly easy to implement. Each mobile simply counts the number of cell-boundary crossings and initiates location update when this number exceeds the predefined movement threshold. Although its LM cost is inferior to that of distance-based schemes, this cost can be decreased by sequential paging methods that take into account mobiles' movement statistics. In this paper, we derive the probability distribution of a mobile's number of cell-boundary crossings during the interval between two location registrations in a movement-based LM scheme for Poisson call arrivals and generally distributed cell residence time. Based on the derived statistics, we obtain the optimal movement threshold and develop an optimal sequential paging scheme. Numeric results are presented to show that the proposed optimal sequential paging scheme outperforms existing sequential paging schemes over a wide range of call-to-mobility ratios

Research on Optimal Paging in Movement-Based Location Management Scheme

Research on Optimal Paging in Movement-Based Location Management Scheme

Optimal location management for two-tier PCS networks

One of the most important issues in Personal Communication Service (PCS) networks is location management, which keeps track of the Mobile Terminals (MTs) moving from place to place. In this paper, we analytically derive cost functions of location updates and paging for a dynamic movement-based location management scheme for PCS networks with two-tier mobility databases. We prove analytically that there is a unique optimal movement threshold that minimizes the total cost of Home Location Register location updates, Visitor Location Register location updates, and paging, per call arrival. An effective algorithm is proposed to find the optimal movement threshold. Furthermore, we propose a hybrid location management scheme, in which when the call-to-mobility ratio is larger than a threshold, the optimal dynamic movement-based scheme is adopted. Otherwise, the static location update is adopted. The Newton approximation method is adopted to find this threshold. Our study shows that the proposed hybrid scheme outperforms both the dynamic movement-based scheme and the static location update scheme.

Analysis of dynamic location management for PCS networks

Location management is a key issue in personal communication service (PCS) networks. Performance analysis plays important roles in the implementation of location management methods and system design in PCS networks. Existing PCS networks have the home location registers (HLRs) and visitor location registers (VLRs) architecture for location management. Some interesting dynamic location management methods are proposed to improve the system performance of PCS networks. However, the existing performance analysis of the dynamic location management methods are too simple and not available for PCS networks with real HLR/VLR architecture. One of the reasons is the complexity and difficulty of the problem. In this paper, we challenge the problem and successfully establish a new analytical model available for the analysis of the important dynamic movement-based location management method for PCS networks.