Location and Configuration Management in Mobile-Switch ATM Networks

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.

This paper studies handoff control mechanisms for mobile ATM networks with private network-network interface (PNNI) hierarchical structure. In this paper, we propose a hierarchical rerouting (HRR) scheme for handoff control which utilizes the PNNI routing information during the path rerouting procedures. The scheme can identify the crossover switch (COS discovery) in a hierarchical fashion, so that the additional signaling delay for the handoff control becomes scalable to the size of the network. Compared with previously available flat rerouting (FRR) schemes, the HRR scheme can effectively reduce the processing time for COS discovery in a PNNI network and, therefore, reduce the handoff latency. Experimental results are obtained using a PNNI network simulator and the performance of typical path rerouting algorithms is evaluated.

Some observations on using meta-heuristics for efficient location management in mobile computing networks

In this paper we tackle the design problem of the trunk group (TG) overlay in wide area ATM networks under reliability constraints. The TGs are composed of virtual paths (VPs) that the soft-permanent virtual connections (S-PVCs) can ride on. The private network-network interface (PNNI) routing standard is used to route these connections. The design problem consists to find the capacity and the administrative weight (AW) of each TG that ensure the successful rerouting of the S-PVCs for all failure scenarios of interest to the network planner. The objective is to minimize the cost of the TG overlay. An optimization model is proposed as well as a tabu search algorithm. A detailed TG overlay design example is performed and tested. The results showed that the tabu-based algorithm has improved the solution by 9.80%.

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.

This talk describes a method for managing the allocation of bandwidth and controlling congestion in ATM networks. The method described provides a complete solution to the problem of efficient resource management in the presence of bursty traffic. The method relies on a technique called fast buffer reservation in which space in link buffers is allocated “on-the fly” to user information bursts at the time the bursts occur, ensuring that a burst, if accepted, has extremely high probability of being delivered intact. We also describe the hardware mechanisms required to implement the method and a fast call acceptance algorithm that ensures that the probability of burst rejection is acceptably small. We conclude that the method is practical and adds only a small incremental cost to an ATM switching system. We restrict ourselves here to the method’s application to point-to-point and one-to-many virtual circuits, but we note that it can also be extended to many-to-many virtual circuits (that is, virtual circuits with multiple transmitters, as well as multiple receivers).

As PCS networks aim to provide 'anytime-anywhere' cellular services, mobile terminals' (MTs) locations should be managed continuously. Location management (LM) includes two processes; registration and paging. Registration concerned with reporting MTs current locations, while, paging locates the callee MT. Both processes incur signalling cost across the wireless channel, which need to be reduced due to the scarcity of PCS wireless bandwidth. In spite of its minimal latency, blanket paging, used in current networks, wastes the network bandwidth. This paper aims to reduce the paging signalling cost under delay bounds. The paper contributions can be summarised as: 1) establishing a family of paging strategies under two proposed probability based LM strategies (PBLM and MPBLM); 2) introducing a novel topology for PCS registration area called the 'hot spot topology' (HST); 3) based on HST, another new LM strategy called 'flower based location management' (FBLM) is introduced. The proposed paging strategies substantially lower the signalling cost compared with the blanket one. Also, experimental results have shown that FBS dramatically reduce the signalling load (up to 80%) with a minimal increase in paging delay.

Optimality of the PNNI (private network-network interface) topology is investigated analytically based on a routing complexity criterion that only depends on the number of nodes in a (sub)network. Results are presented for a complexity that is quadratic in the number of nodes because this case corresponds to the complexity of the well-known Dijkstra routing algorithm. The resulting optimal PNNI topology is highly symmetrical (all peer groups on a same hierarchical level are of equal size). Moreover, the lowest (physical) peer group size consists only of a few nodes, while, surprisingly perhaps, just a couple of hierarchical levels are needed to span a global network of 10/sup 10/ nodes. Routing algorithms with a higher nodal complexity than Dijkstra's benefit from a higher complexity reduction using a hierarchical PNNI optimal topology.

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.

Benefits of mobile end user network switching and multihoming

Location management techniques for mobile systems

Location management is one of the most important issues in mobile radio communication systems. This paper presents an intelligent paging scheme which uses geographical information to help in searching for the target mobile terminal. Since the characteristics of geography, such as street placement, mountain areas, lack locations, etc., influences the distribution of mobile users, the probability of user distribution among each registration zone is quite different. According to the probability information, we may track a mobile user by utilizing the geographical background information. Three different paging policies are proposed. Simulation results demonstrate that the proposed schemes significantly improve the location management performance.

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.

Location management deals with how to track mobile users within the cellular network. It consists of two basic operations: location update and paging. The total location management cost is the sum of the location update cost and the paging cost. Location areas and reporting centers are two popular location management schemes. The motivation for the study is the observation that the location update cost difference between the reporting centers scheme and the location areas scheme is small whereas the paging cost in the reporting centers scheme is larger than that in the location areas scheme. The paper compares the performance of the location areas scheme and the reporting centers scheme under aggregate movement behavior mobility models by simulations. Simulation results show that the location areas scheme performs about the same as the reporting centers scheme in two extreme cases, that is, when a few cells or almost all cells are selected as the reporting cells. However, the location areas scheme outperforms the reporting centers scheme at the 100% confidence level with all call-to-mobility ratios when the reporting cells divide the whole service area into several regions.

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.