Performance comparison of location areas and reporting centers under aggregate movement behavior mobility models

In this paper, we develop an analytical model of the signaling costs due to location update and paging for the radio interface in mobile communications networks. This model accounts for the effects that the savings brought by different algorithms have on the total Location Management (LM) costs. It also takes into account the trade-off between the location update and paging costs, showing that those strategies that achieve savings in the location update costs deliver a larger overall improvement in the total LM costs than those algorithms focusing on the minimization of the paging costs. Moreover, leveraging the factors studied to obtain this model, we also analyze the overall LM costs including the fixed network part.

The scarce radio resources available to any cellular radio network have to be shared between its revenue-generating voice- and data-carrying services, and non-revenue-generating management services. One of these management services is location management, crucial for the network to keep track of the location of its subscribers and to connect their incoming calls. Location management consists of the two activities, paging and location updating, both of which are structured around a subdivision of the network service area called the location area (LA). The ways in which the service area is partitioned therefore has a direct impact on the amount of radio bandwidth that has to be spent on location management. However, paging and location updating share an antagonistic relationship, and finding the optimal LA partitioning that strikes a balance between the two is a challenging design problem. In this paper, the problem of finding the optimal LA partitioning of a cellular radio network service area in order to minimise the total location management signalling cost is addressed. The choice of the decision variables used in the mathematical programming model results in an objective function that is conceptually easy to understand and a solution method that is simple and straightforward.

This paper aims at improving the distance-based location management scheme for mobile communication networks. In location management, a mobile terminal (MT) is tracked based on its location-update area (LA). The improvement is brought about by joint optimization of LA center and LA size. For LA center optimization (LCO), we determine the optimal center position of the LA given the initial position of the MT upon each location update. The investigation of optimal LA center has eluded research to date. Based on the popular continuous-time random walk (CTRW) mobility model, we propose an analytical framework that uses a diffusion equation to determine the optimal LA center that minimizes the total cost of location management, consisting of the location update cost and terminal paging cost. This framework allows us to easily model the non-Markovian movement of the MT and evaluate the impact of various measurable physical parameters (such as length of road section, angle between road sections, and road section crossing time) and LA center. In particular, we show that proper LA center can significantly reduce the total cost. For example, for the circular LA and low Poisson call-arrival rate, optimizing the LA center alone has the potential of reducing the cost by up to 37 percent. Joint optimization of the LA center and terminal paging scheme can reduce the cost even further. Simulations results match the theoretical analysis to a gap within 3 percent, indicating that our theoretical model is very accurate.

Location management is the basis for ensuring service continuity in low earth orbit (LEO) satellite mobile communication systems. The dual mobility of LEO satellites and mobile users triggers frequent location update procedures, which will increase the network location management overhead and bring great challenges to network location management, especially in the mega satellite networks. In this paper, we propose a location management technology solution for mega satellite networks, including location management architecture, location area design, location update, and paging procedures. A medium earth orbit (MEO) satellite-assisted location management architecture is proposed to improve the efficiency of location management. It extends the location management control plane from the ground to space and adopts a distributed location management mechanism. A dual location area, including the satellite location area and user location area, is designed to balance the network location update and paging overhead. Based on the dual location area, we systematically design low-overhead location update and paging procedures. Simulation results have verified that the proposed location management technology solution can reduce the total location management overhead and delay by at least 45.8% and 20.8%, respectively.

The paper proposes an integrated location management scheme, based on our previously proposed novel rule-based paging scheme (RBPS) for reducing the cost of terminal paging in a cellular wireless environment. We extend that scheme to propose a complete location management scheme. This requires application of RBPS together with a judicious movement based location update (LU) scheme. Numerical results show that the proposed integrated location management scheme, called RBPS*, not only attempts to resolve the issue of inherent tradeoff between the cost components, comprised of paging and LU cost, but also does reduce the total cost for location management compared to the other schemes. RBPS* significantly outperforms RBPS and the GSM-adopted blanket paging scheme along with movement based LU. When compared with the popular shortest distance first (SDF) scheme, results are again encouraging. The proposed scheme, RBPS*, is a generic one and can be deployed on-line. It has the potential for use in next generation wireless networks, irrespective of any standards.

LOCATION MANAGEMENT AND COST PLANNING FOR PERSONAL COMMUNICATION SYSTEMS

A practical information theoretic framework is developed for studying the optimal tradeoff between location update and paging costs in cellular networks. The framework envisions the quantization of location information into a registration area (RA) level granularity, followed by the use of an entropy-coding technique to decrease the location update rate. The rate distortion theory of the lossy quantization is identified as an appropriate measure for capturing the optimal tradeoff between a mobile's update rate and its location uncertainty. Based on LZ-78 compression, two different RA-level location update algorithms (RA-LeZi and LeZi-RA) have been developed, both of which asymptotically approach this rate-distortion bound. By allowing for quantization loss in the mobile node's movement pattern, this framework can reduce the overall update cost below the entropy bound associated with the original loss-less LeZi-update mobility management algorithm. Simulation results demonstrate a sharp decrease (/spl sim/ 50%) in the update cost, at the expense of a minor (/spl sim/ 25%) increase in the overall location management costs. The key essence of this framework lies in its practical applicability, because today's wireless networks already track the mobile user at an RA-level granularity.

In this paper, we propose two information-theoretic techniques for efficiently trading off the location update and paging costs associated with mobility management in wireless cellular networks. Previous approaches always attempt to accurately convey a mobile's movement sequence and hence cannot reduce the signaling cost below the entropy bound. Our proposed techniques, however, exploit the rate distortion theory to arbitrarily reduce the update cost at the expense of an increase in the corresponding paging overhead. To this end, we describe two location tracking algorithms based on spatial quantization and temporal quantization, which first quantize the movement sequence into a smaller set of codewords and then report a compressed representation of the codeword sequence. Although the spatial quantization algorithm clusters individual cells into registration areas, the more powerful temporal quantization algorithm groups sets of consecutive movement patterns. The quantizers themselves are adaptive and periodically reconfigure to accommodate changes in the mobile's movement pattern. Simulation study with synthetic and real movement traces for both single-system and multisystem cellular networks demonstrate that the proposed algorithms can reduce the mobile's update frequency to 3-4 updates/day with reasonable paging cost, low computational complexity, storage overhead, and codebook updates.

Location management is a paramount issue in wireless mobile station communication systems to enable the terminals to continuously receive services when moving from one location to another. In this paper, we study the trends in the latest cellular wireless systems to page terminals, update location area and make handover decisions for a mobile station. Topics covered include static and dynamic location management, dynamic location areas and techniques, future location management developments, location tracking evolution and location management in 3G. It will be shown that location-area based location management methods designed around a profile or history-based direction information offer the best performance, in terms of location management cost, compared to all other alternative approaches while distance based schemes are to be the most efficient ones.

The growth of cellular subscribers and the increasing communication activities have generated a lot of signaling transactions in PCS network. In location management perspective, the effect of user mobility will affect signaling transactions in location update and paging operations. In this paper, we evaluate the impact of mobility activity and analyze the signaling activities in registration system: visitor location register and home location register. The number of signal transactions in HLR and VLR in terms of network resources is analyzed to obtain an efficient location management strategy. Distanced-based location update and sequential paging approach are used to evaluate the PCS network performance. First, the activity cost calculation is proposed to evaluate the mobility activities under these approaches. Then, three strategies based on location area concept which cells grouped into: single-cell, balanced-cell, and unbalanced-cell are introduced to measure the network performance for location management operations. Each of these strategies incorporates the same cell size but with different number of cells based random mobility model with 1/6 direction probability. The simulation evaluation shows that the number of signaling activity is dependent on user mobility and the chosen strategy. Results show that the location area approach give better signaling activity cost and the balanced-cell strategy outperforms in terms of signaling registration compared to the single-cell and unbalanced-cell strategies.

Mobility management is an important aspect in LEO systems. In terrestrial wireless networks, the movement of the user triggers location updating and determines the paging scheme, while in LEO satellite systems, location updating and paging is mainly based on the movement of satellites. Terrestrial location management techniques must be altered to fit LEO systems. The paper introduces a modified movement-based location update and paging scheme in LEO networks. We propose the meta-cell concept, which includes two spot-beams of one satellite. First, we present a location management scheme based on the architecture with a meta-cell location area. Then, an analytical model is applied to formulate the cost of location updating and location paging for the movement and meta-cell based dynamic location update scheme. The comparison of performance between the meta-cell architecture method and the conventional signal-spot-cell architecture method is provided to demonstrate the cost-effectiveness and robustness of the proposed scheme under various parameters. To reduce the impact of meta-cell architecture on location paging cost, we present a forced location update strategy which is used in the case that the meta-cell includes two spot-beams from different satellites.

Location management which keeps track of the mobile terminals moving from place to place in a wireless networks is a key issue in resource management particularly in 3G cellular networks. Two basic operations are involved in location management: location update and paging. It is necessary to provide a good trade off between location update and paging to reduce the total cost. This goal however needs good algorithms for both registration and paging. We propose a dynamic movement-base location management scheme for 3G networks where Home Location Registers (HLR's), Gateway Location Registers (GLR's), and Visitor Location Registers (VLR's) are formed into three level hierarchical mobility data base structure. A simulator based on MATLAB which can study location update and paging performance was developed. It is expected that the average number of location updates could be reduced using the movement-base scheme.

Application of AI techniques for locating mobile terminals in mobile wireless cellular networks: A novel paging scheme

Cellular mobile systems provides access to a wide range of services and allow mobile terminals (MTs) to move randomly from one place to another within a well-defined geographical area. Due to the growing number of mobile users, global connectivity, and the small size of cells, one of the most critical issues regarding these networks is location management. The challenging task in a cellular system is to track the location of the mobile users effectively so that the connection establishment cost and delay is low. In recent years, several strategies have been proposed to improve the performance of the location management procedure in cellular networks. In this paper, we propose an intelligent approach by taking the User Profile History (UPH); to reduce the location update cost by combining Back-Propagation Algorithm and Cascaded Correlation Neural Network. The implementation of this strategy has been subject to extensive tests. The results obtained confirm the efficiency of UPH in significantly reducing the costs of both location updates and call delivery procedures when compared to the various other strategies well-known in the literature.

Efficient paging techniques are needed to reduce the cost of location management in mobile networks. Currently, all the cells of a location area (LA) are paged at the same time to locate the mobile user (MU). Efforts have been made to reduce the overhead paging bandwidth cost by using multi-step paging methods. However, in the case of multi-step paging schemes, such as sequential paging and intelligent paging, additional paging delay is introduced. It is shown that if the paging cost computation is based on the number of paged cells only, then, in certain cases, one may obtain misleading results. To resolve this dilemma, a new cost function, in terms of the number of cells paged and the paging delay, is introduced. Thus, this new metric provides a powerful tool that can be used to analyze all multi-step paging procedures with constrained or unconstrained delay.