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.     

Database and location management schemes for mobile communications

Signaling traffic incurred in tracking mobile users and delivering enhanced services causes an additional load in the network. Efficient database and location management schemes are needed to meet the challenges from high density and mobility of users, and various service features. In this paper, the general location control and management function is treated as the combination of two parts, the global and local scope. New schemes and methods are proposed, and improvements achieved over established basic schemes are shown by using simulations     

Joint detection and combining schemes in MIMO-HARQ systems

This article mainly investigates the combining schemes for hybrid automatic retransmission request (HARQ) protocols in multiple-input multiple-output (MIMO) wireless communication systems. A novel scheme, which joins MIMO detection and HARQ combining, called mid-combining, is presented in this article. Based on the position of HARQ combining, we classify the HARQ combining schemes into three types, named pre-combining, mid-combining, and post-combining. The simulation results show that mid- combining can increase the system throughput for all SNRs.     

Performance of cell loss priority management schemes in a single server queue

The throughput optimality of priority management strategies in a single buffer has been studied for a general aggregate arrival law. The tight upper bounds found are useful to understand optimality in the utilization of specific priority schemes such as push-out buffer (POB) and partial buffer sharing (PBS). This paper further focuses on the maximum allowable load ρ_max versus the priority mix α for a PBS and a random push-out buffer (RPOB) of size K for a wide variety of arrival processes. The role of priorities in a special type of bursty arrivals, the compound Poisson process with constant burst length and random priority assignment within the burst is found to be less pronounced than that of ‘pure’ Poisson arrivals. On the other hand, the results for ON–OFF cell arrivals modelled by a MMPP(2), MMPP(3), and higher order Markov modulated processes (MMP) closely follow the behaviour of the maximum allowable load in the RPOB with Poisson arrivals, however, scaled to lower loads. The results indicate that the priority mix distribution within the aggregate arrival flow influences the shape of ρ_max(α)-curve more than the aggregate arrival distribution itself. © 1997 John Wiley & Sons, Ltd.     

Secure and efficient binding updates in host-based distributed mobility management

Wireless Networks - Rapid evolution in mobile communication is geared toward reliable and responsive network connectivity, thereby necessitating a network protocol operated in a distributed...     

Knowledge structure representation and automated updates in intelligent information management systems

Work reported in this paper is part of a continuing effort to apply rapid prototyping and Artificial Intelligence techniques to problems associated with projected Space Station-era information management systems. In particular, timely updating of the various databases and knowledge structures within our proposed intelligent information management system (IIMS) is critical to support decision making processes. Because of the significantly large amounts of data entering the IIMS on a daily basis, information updates will need to be automatically performed with some systems requiring that data be incorporated and made available to users within a few hours. Meeting these demands depends first, on the design and implementation of information structures that are easily modified and expanded, and second, on the incorporation of intelligent automated update techniques that will allow meaningful information relationships to be established. This paper examines potential techniques for developing such an automated update capability and examines IIMS update requirements in light of results obtained from our IIMS prototyping effort.     

基于多跳蜂窝网的组位置管理策略

提出了一种成组进行位置管理的策略,分析了彼此临近的移动台组成一个自组织网的基本网络模型,提出了向中继点注册,由中继点进行信令压缩,组成组控制信令,成批向网络报告位置的位置更新的策略;采用M/M/n/n模型具体比较了批处理方案与传统方案的性能,说明作者的方案不仅减少了移动台的发射功率,还大量节省了频率资源,增加了系统的吞吐能力。     

Enhanced distance-based location management of mobile communication systems using a cell coordinates approach

In managing the locations of mobile users in mobile communication systems, the distance-based strategy has been proven to have better performance than other dynamic strategies, but is difficult to implement. A simple approach is introduced to implement the distance-based strategy by using the cell coordinates in calculating the physical distance traveled. This approach has the advantages of being independent of the size, shape, and distribution of cells, as well as catering for the direction of movement in addition to the speed of each mobile terminal. An enhanced distance-based location management strategy is proposed to dynamically adjust the size and shape of location area for each individual mobile terminal according to the current speed and direction of movement. It can reduce the location management signaling traffic of the distance-based strategy by half when mobile terminals have predictable directions of movement. Three types of location updating schemes are discussed, namely, Circular Location Area, Optimal Location Area, and Elliptic Location Area. Paging schemes using searching techniques such as expanding distance search based on the last reported location and based on the predicted location, and expanding direction search are also explored to further reduce paging signal traffic by partitioning location areas into paging areas.     

Performance evaluation of location management in UMTS

The universal mobile telecommunications system utilizes a three-level location-management strategy to reduce the net costs of location update and paging in the packet-switched service domain. Within a communication session, a mobile station (MS) is tracked at the cell level during packet transmission. In the idle period of an ongoing session, the MS is tracked at the UTRAN registration area (URA) level to avoid frequent cell updates while still keeping the radio connection. If the MS is not in any communication session, the MS is tracked at the routing-area (RA) level. The inactivity counter mechanism was proposed in 3GPP 25.331 to determine when to switch between the three location-tracking modes. In this mechanism, two inactivity counters are used to count the numbers of cell and URA updates in an idle period between two packet transmissions. If the number of cell updates reaches a threshold K/sub 1/, the MS is switched from cell tracking to URA tracking. After that, if the number of URA updates reaches a threshold K/sub 2/, the MS is tracked at the RA level. The paper proposes analytical and simulation models to investigate the performance of the inactivity counter mechanism. Our study provides guidelines for K/sub 1/ and K/sub 2/ selection to achieve lower net costs of location update and paging.     

Cluster-based location service schemes in VANETs: current state,challenges and future directions

Vehicular Ad hoc Networks (VANETs) have drawn incredible interest in both academic and industrial sectors due to their potential applications and services. Vehicles’ position plays a significant role in many location-based applications and services such as public emergency, vehicles tracking, resource discovery, traffic monitoring and position-based routing. A location service is used to keep up-to-date records of current positions of vehicles. However, locating vehicles’ positions and maintaining an accurate view of the entire network are quite challenging tasks due to the high number of nodes, and high and fast nodes mobility which results in rapid topological changes and sudden network disconnections. In the past literature, various location-based services have been proposed to solve the above mentioned issues. Moreover, the cluster-based location service schemes have gained a growing interest due to their advantages over non-cluster-based schemes. The cluster-based schemes improve the network scalability, reduce the communications overhead and resolve the mobility issues within the clusters preventing them from propagating in the whole network. Therefore, this paper presents the taxonomy of the existing location service schemes, inspects the cluster-based location service by highlighting their strengths and limitations, and provides a comparison between location-based clustering and application specific clustering such as the one used in routing, information dissemination, channel access management and security. In addition, the existing clustering schemes, challenges and future directions for efficient cluster-based location service are also discussed.

     

The distribution of intervals between zero crossings of sine wave plus random noise and allied topics

Using the first term of a series given by Longuet-Higgins [5] for the general case an approximate solution is found in the form of a double integral for the distribution of intervals between zero crossings of a waveform consisting of sine wave plus random noise. For the important case of fairly large signal to noise ratio (SNR) this integral is evaluated approximately in closed form. In the limit as the SNR becomes very large indeed, this tends to a Gaussian distribution. Comparison is made between the approximate forms and numerical evaluation of the double integral. Good agreement results. An example of the use of this distribution is the transmission of binary data over telephone lines by frequency modulation. With a choice of two out of three possible frequencies to use, it is shown that a satisfactory error rate can only be obtained with the use of the two extremes. This is in accordance with the practical experiments of Jenks and Hannon [4]. Also given is an asymptotic form for the average rate of crossing of any level. This is somewhat different from that of Rice [9] and has been found easier to use in suitable conditions. For the zero level another simple form is given valid when the first is not.     

On-line estimation and location of non-technical losses in a distribution system

Remote diagnosis of electrical distribution networks contributes greatly to their global performance, obviously on technical grounds, but also on 3 economic factors: 1) the reduction of technical losses through a detailed knowledge of all energy flows at various nodes of the network; 2) the optimization of investments and of operational costs through precise information on the network status and its operation conditions and 3) the improvement of the energy dependability (availability and quality) through close monitoring of the energy delivery conditions and the identification of the possible need for correction and their most efficient locations. There is a fourth economic factor, relevant for distribution companies: the reduction of total losses through the reduction of the non-technical losses. This paper demonstrates for the first time a method to calculate and locate on-line the non-technical losses in a distribution system. All these factors largely justify the implementation of a DMS system including a corporate IT platform to feed data from the GIS (or other information systems, NIS, etc.) on a central data base repository and the means to capture and maintain the model data.     

Robustness of real and virtual queue-based active queue management schemes

In this paper, we evaluate the performance of both real and virtual queue-based marking schemes designed for use at routers in the Internet. Using fluid flow models, we show via analysis and simulations that Virtual Queue (VQ)-based marking schemes outperform Real Queue (RQ)-based marking schemes in terms of robustness to disturbances and the ability to maintain low queueing delays. In fact, we prove that a linearized model of RQ-based marking schemes exhibit a lack of robustness to constant but otherwise unknown levels of disturbances. The analytical results we present are applicable to combinations of proportionally fair and TCP-type congestion controllers at the source, and Random Exponential Marking (REM) and Proportional Control (PC) schemes at the router. The behavior of Random Early Discard (RED) and Proportional-Integral (PI) control schemes at the router are also studied via simulations.     

The Cramer-Rao bounds of hybrid TOA/RSS and TDOA/RSS location estimation schemes

The Cramer-Rao bound (CRB) on location estimation accuracy of two different hybrid schemes, time of arrival/received signal strength (TOA/RSS) and time difference of arrival/received signal strength (TDOA/RSS), is computed. For short-range networks, the hybrid schemes offer improved accuracy with respect to conventional TOA and TDOA schemes, particularly in the proximity of the reference devices.     

Joint design and management of energy-aware Mesh Networks

This paper deals with the joint planning and energy management operation of Wireless Mesh Networks. We claim that energy management should be incorporated at the planning stages to produce an effective energy-management operation. For this, we propose a mathematical framework that takes into account the trade-off of capital expenditures vs. energy-related operational ones when designing the network. We also present results that put into relevance the impact of different coverage policies on energy efficiency.     

TD-SCDMA系统混合业务下的无线资源管理算法研究

给出了智能天线技术在系统级研究的理论模型，推导了采用多用户检测和自适应智能天线技术后的容量和负载评估理论模型。基于该模型，给出了一种新的接入控制算法，并为实时多媒体业务提出了一种先进的动态信道分配算法。仿真结果表明，提出的理论模型和无线资源管理算法适用于TD-SCDMA系统，能够显著提高系统性能，用于实际TD-SCDMA网络的规划优化。     

全分布式位置管理策略的负载和位置更新性能研究

分布式位置管理策略及其分布式数据库结构与传统位置管理策略和HLR－VLR结构有显著区别，本文基于一种对DDB结构新的性能估计方法，从用户的移动性概率分布出发，对DDB结构下的数据库负载和位置更新性能进行了研究。     

配网自动化建设与配电运行管理观察

配电网系统是电力系统中用于分配电能的部分,其运行状态将关系到每家每户居民的用电情况。为了保证人们用电的稳定,相关配电部门需要加强对配网自动化的建设和对配电运行管理的研究,对于在配网系统自动化建设过程中遇到的难题要采取应对措施及时解决。本文就配网系统自动化建设中出现的问题以及加强配电运行管理的方法进行分析,希望能为配电网系统自动化提供一定的参考价值。     

Simulation and analysis of Awerbuch–Peleg and GSM schemes for location tracking of mobile users

Mobile users are increasingly demanding full access to networked communications while they are on the move. Several studies have shown that the overhead incurred by the network to keep track of the current location of mobile users is considerably high. The methods currently used for location tracking incur heavy unnecessary costs by requiring that users update locations in their home networks after each move regardless of the distance at which the move occurs, and that all search attempts for a mobile user are first routed to that user's home network. The Awerbuch–Peleg scheme presents a formal model for location tracking which attempts to minimize the cost of local operations—both move and find operations—through the construction of a regional hierarchy. In this paper we present a performance evaluation of the Awerbuch–Peleg scheme. We also compare its performance to that of the GSM‐based location tracking scheme. It is found that the Awerbuch–Peleg scheme in general results in higher costs than the GSM scheme. The reason for this is found to be some unexpected properties of the read and write sets which are key components of the Awerbuch–Peleg scheme. Copyright © 2001 John Wiley & Sons, Ltd.     

Packet loss performance of selective cell discard schemes in ATMswitches

In transport-layer protocols such as TCP over ATM networks, a packet is discarded when one or more cells of that packet are lost, and the destination node then requires its source to retransmit the corrupted packet. Therefore, once one of the cells constituting a packet is lost, its subsequent cells of the corrupted packet waste network resources. Thus, discarding those cells will enable us to efficiently utilize network resources, and will improve the packet loss probability. We focus on tail dropping (TD) and early packet discard (EPD) as selective cell discard schemes which enforce the switches to discard some of the arriving cells instead of relaying them. We exactly analyze the packet loss probability in a system applying these schemes. Their advantages and limits are then discussed based on numerical results derived through the analysis