Adaptive paging schemes for group calls in mobile broadband cellular systems

In this paper, we analyze the problem of efficient paging for group call searches under realistic mobility patterns. Taking as a basis a location update scheme, based on the definition of an adaptive macro‐location area, adapted to the mobility pattern of the terminals, we characterize the residence probabilities in each location area of a generic macro‐area. With this information, we propose and evaluate different sequential group paging strategies, also taking into account their computational cost. Results show the suitability of some of the proposals (semiadaptive and hybrid schemes) and its applicability to new packet‐based broadband cellular systems. Copyright © 2010 John Wiley & Sons, Ltd.     

A learning strategy for paging in mobile environments

The essence of designing a good paging strategy is to incorporate the user mobility characteristics in a predictive mechanism that reduces the average paging cost with as little computational effort as possible. In this scope, we introduce a novel paging scheme based on the concept of reinforcement learning. Learning endows the paging mechanism with the predictive power necessary to determine a mobile terminal's position, without having to extract a location probability distribution for each specific user. The proposed algorithm is compared against a heuristic randomized learning strategy akin to reinforcement learning, that we invented for this purpose, and performs better than the case where no learning is used at all. It is shown that if the user normally moves only among a fraction of cells in the location area, significant savings can be achieved over the randomized strategy, without excessive time to train the network. Copyright © 2003 John Wiley & Sons, Ltd.     

Optimal TCP segment size for mobile server access over wireless links of cellular networks

Internet access from mobile phones over cellular networks suffers from severe bandwidth limitations and high bit error rates over wireless access links. Tailoring TCP connections to best fit the characteristics of this bottleneck link is thus very important for overall performance improvement. In this work, we propose a simple algorithm in deciding the optimal TCP segment size to maximize the utilization of the bottleneck wireless TCP connection for mobile contents server access, taking the dynamic TCP window variation into account. The proposed algorithm can be used when the product of the access rate of the wireless link and the propagation time to mobile contents servers is not large. With some numerical examples, it is shown that the optimal TCP segment size becomes a constant value when the TCP window size (WS) exceeds a threshold. One can set the maximum segment size (MSS) of a wireless TCP connection to this optimal segment size for mobile contents server access for maximum efficiency on the expensive wireless link. Copyright © 2007 John Wiley & Sons, Ltd.     

Optimal Sequential Paging in Cellular Wireless Networks

In a high-capacity cellular network with limited spectral resources, it is desirable to minimize the radio bandwidth costs associated with paging when locating mobile users. Sequential paging, in which cells in the coverage area are partitioned into groups and paged in a non-increasing order of user location probabilities, permits a reduction in the average radio costs of paging at the expense of greater delay in locating the users. We present a polynomial time algorithm for minimizing paging cost under the average delay constraint, a problem that has previously been considered intractable. We show the conditions under which cluster paging, a simple heuristic technique proposed for use with dynamic location update schemes, is optimal. We also present analytical results on the average delay and paging cost obtained with sequential paging, including tight bounds.     

Optimal channel assignment in cellular networks

In this paper, we consider the problem of assigning frequencies to mobile terminals in a cellular network. We show that an optimal solution can be obtained by solving a sequence of alternating linear and quadratic maximization programming problems. We address co-channel constraints and adopt as an objective function the maximization of potentially established calls. Our algorithm is fairly general, and does not depend on any special network structure. This study indicates that mathematical programming can be used as an efficient technique for solving the aforementioned problem.     

A Combination of Optimal Partitioning and Location Prediction to Assist Paging in Mobile Cellular Networks

The correlated both in space and time user mobility behavior can aid significantly in the localization of a moving terminal in the network coverage area. However, there is always some uncertainty in mobile user position and a network-wide search cannot be done. Therefore, a predictive paging scheme must always be combined with a location update strategy and a compatible algorithm to conduct the search. In this paper, we introduce a new strategy that combines an optimal partitioning of the location area (LA) with a model to predict user movements, based on the additional information of the cell where the last interaction between the network and the terminal took place. We study the performance of the strategy under delay bounds and different mobility and call arrival characteristics. It is found that the new scheme further minimizes signaling costs and enhances previous sequential paging algorithms.     

Efficient paging and multicast schemes for Mobile Virtual Private Networks

The issue of providing a mobile virtual private network (MVPN) service by a cellular network is addressed in this study. The main focus of this study is on two aspects of MVPN handling: a multicast transmission, and location management of the MVPN members. Virtual private networks (VPNs) already exist in wired networks. The growing number of mobile users increases the demand for mobile services. It is expected that future wireless networks will have to provide wireless internet services, and in particular, to support MVPNs. In order to maintain an MVPN service offering, the system must support an efficient information delivery to the MVPN members. In order to achieve this goal, the physical locations of the MVPN members must be known to the system. In this study, we present methods to efficiently route and transmit information to the MVPN members, without affecting the quality of the personal service provided to each and every MVPN member. It is shown that the wireless MVPN bandwidth requirement is significantly less than the equivalent bandwidth required by a wired VPN. The offered bandwidth utilization is significantly better than the efficiency of IP‐based multicast transmission in the Internet, and the proposed IP‐based multicast transmission in cellular networks. Copyright © 2005 John Wiley & Sons, Ltd.     

Performance bounds of a multiple-step paging strategy in future universal mobile telecommunication systems

In future mobile telecommunications, due to the huge number of users and the specific functions that support mobility, a significant amount of signaling load will have to be carried by the finite capacity of the radio link. Hence, methods aiming at radio link signaling load reduction are welcome. In this paper we propose and analyze a method that saves paging signaling load by exploiting information related to the terminal location during the most recent interaction between the terminal and the network. The penalty paid is extra processing power and extra paging delays. An analytical model is developed so as to describe the performance versus traffic intensity and mobility conditions. The performance of the proposed paging scheme is investigated, and it is shown that the method operates well even in the worst case, which is the high user mobility conditions. Possible extensions of the method, which exploit information related to the mobility degree of each individual user or information characterizing the mobility conditions in a certain location area, are also proposed.This paper has been partially funded by CEC through the RACE 2066 Mobile Network (MONET) project. The paper does not present the views of the project as a whole, but those of the authors.     

Ensemble polling strategies for increased paging capacity in mobile communication networks

The process of finding a unit in a mobile communications system is called paging and requires the use of limited network resources. Although it is understood how to minimize the use of network resources and satisfy delay constraints when paging a single unit, optimal policies for paging multiple units are difficult to derive. Here we adapt single unit polling methods to obtain simple ensemble polling schemes for use with multiple units which can greatly increase the rate at which page requests can be processed while maintaining acceptable average delay. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of dormant registration on performance of mobility management based on IP paging in wireless data networks

Unlike traditional cellular networks, which provide mainly voice services, there is, at present, no method that enables the effective management of terminal mobility for both active and idle mobile terminals in data networks. Although IP paging has been introduced to reduce power consumption of dormant mobile terminals, there is no concern to design an effective IP paging method for real wireless environments. Therefore, we propose a new dormant registration based IP paging method and analyze the effect of the dormant registration threshold used in IP paging on the performance of mobility management. Moreover, we demonstrate the importance of selecting an appropriate value for the dormant registration threshold.     

基于移动元胞自动机的网络舆情传播模型

为了准确刻画网络舆情的变化规律,针对经典元胞自动机存在的不足,考虑网络舆情主体的可移动因素,提出一种基于移动元胞自动机的网络舆情传播模型。首先对经典元胞自动机的工作原理进行分析,提出移动元胞自动机模型,然后根据网络舆情的特点,制定网络舆情主体状态转换规则和移动规则,建立移动元胞自动机的网络舆情传播模型,最后采用Matlab 2011对网络舆情演化过程进行仿真分析。仿真结果表明,舆情主体移动概率对网络舆情传播速度和同质化率影响比较大,移动元胞自动机模型可以很好地描述网络舆情的实际传播过程。     

基于泰勒级数展开的蜂窝TDOA定位算法

基于用户位置的应用已经成为移动数据业务的重要组成部分,使得蜂窝系统用户定位技术成为蜂窝移动通信领域的研究热点。泰勒级数展开算法因为具有精度高和顽健性强等特点而在求解非线性定位方程组中得到了广泛的应用,但它对初始值有很强的依赖性。本文使用最小二乘方法估计用户位置的初始值并使用泰勒级数展开算法确定用户坐标。通过对算法的仿真分析,结果表明本算法具有近似于基于真实值的泰勒级数展开算法的性能。     

Markov mobility model and registration area optimization in cellular networks

In cellular communication systems, in order for a network to keep track of inactive mobile stations (MSs), each inactive MS has to update its location from time to time, called location registration. To lighten the task of tracking inactive MSs, the network divides its cells into groups, called location areas (LAs) and tracks inactive MSs at the LA level: an inactive MS sends a registration message to the network to update its location only when it travels to a new LA. Obviously, the performance of a location area design depends on network traffic and the mobility of MSs. In the paper, we propose a general Markov mobility model for MSs in cellular networks, provide a procedure to automatically estimate the system parameters according to the network traffic, derive the performance of LA design, and provide a clustering algorithm to optimize LA designs. A numerical example is provided to show the effectiveness of the proposed procedures. Copyright © 2009 John Wiley & Sons, Ltd.     

Hierarchical location service for wireless sensor networks with mobile sinks

In wireless sensor networks (WSNs), a mobile sink can help eliminate the hotspot effect in the vicinity of the sink, which can balance the traffic load in the network and thus improve the network performance. Location‐based routing is an effective routing paradigm for supporting sink mobility in WSNs with mobile sinks (mWSNs). To support efficient location‐based routing, scalable location service must be provided to advertise the location information of mobile sinks in an mWSN. In this paper, we propose a new hierarchical location service for supporting location‐based routing in mWSNs. The proposed location service divides an mWSN into a grid structure and exploits the characteristics of static sensors and mobile sinks in selecting location servers. It can build, maintain, and update the grid‐spaced network structure via a simple hashing function. To reduce the location update cost, a hierarchy structure is built by choosing a subset of location servers in the network to store the location information of mobile sinks. The simulation results show that the proposed location service can significantly reduce the communication overhead caused by sink mobility while maintaining high routing performance, and scales well in terms of network size and sink number. Copyright © 2009 John Wiley & Sons, Ltd.     

A virtualized resource management scheme for heterogeneous cellular networks

Because of random deployment patterns of femtocells, interference scenarios in a heterogeneous cellular network can be very complicated because of its changing network topology. Especially when each eNodeB occupies a fixed bandwidth, interference management becomes much more difficult. The benefit of dynamic management for local resource optimation is limited. Recently, resource virtualization has been proposed as a dynamic resource management scheme to optimize network performance. In fact, resource virtualization is viewed as a more flexible model, in which mobile network service providers can control physical resources in a global scope. This paper presents a joint resource virtualization and allocation scheme for its applications in heterogeneous macro‐femto‐cellular networks. The proposed scheme involves two major processes. First, it virtualizes physical resources as logical resources. Second, it carries out logical resource allocation optimization globally and aggregates logical and physical resources for resource allocation. The proposed scheme takes into account spectrum reuse and frequency domain interference jointly in order to achieve a high spectral efficiency and provide rate‐on‐demand services to all users. Simulation results demonstrate the effectiveness of the proposed scheme. Copyright © 2016 John Wiley & Sons, Ltd.     

Assigning cells to switches in cellular mobile networks using hybridizing API algorithm and Tabu Search

Cells assignment to switches plays an important role in the area of resource management in cellular network. Efficient homing of cells to switches can have a significant impact on handoff and cabling costs. This problem is an NP‐hard problem, which cannot be solved by conventional optimization algorithms. It is therefore necessary to use metaheuristic methods to solve it. This research proposes a hybrid heuristic approach for further improving the quality of solutions. This approach applies API ant algorithm in combination with one of the best heuristics used to solve this problem: Tabu Search. A key element in the success of this hybrid approach is the use simultaneously an intensified research on several areas of research space. The implementation of these algorithms has been subject to extensive tests. In comparison with previous research, the proposed method is efficient, regarding quality of solutions provided for moderate‐sized and large‐sized cellular mobile networks. Copyright © 2013 John Wiley & Sons, Ltd.     

A modified poisson distribution for smartphone background traffic in cellular networks

For the emerging applications such as Google Talk, Facebook, Skype and QQ, to mention a few, which run on smartphones, background traffic has become one of the significant issues in system design and optimization. Because of the complicated user behavior and interaction, the assumptions underlying the Poisson process model cannot be met; the Poisson distribution cannot approximate the distribution of background traffic arrivals accurately. In this paper, we propose a model, which can better fit the background traffic arrivals of smartphones than the Poisson distribution. The proposed model is a linear transformation of the Poisson distribution and is specified by three parameters, (a ,b ,λ ), which can be estimated from the measured sample's mean, variance, and third central moment. Simulation results have corroborated the fitness of the proposed model in both single and mixed applications scenarios. In addition, we have also observed that the normalized parameters, (a ,b ₀,λ ₀), of each application is independent of the user number and completely characterized by the type of application. Hence, with the given trace cumulative distribution functions of all applications, the proposed modified Poisson distribution can be used as a tool for modeling and analyzing background traffic arrivals with arbitrary user numbers and mixed applications. Copyright © 2016 John Wiley & Sons, Ltd.     

Call admission control in mobile cellular networks: a comprehensive survey

Call admission control (CAC) is a key element in the provision of guaranteed quality of service (QoS) in wireless networks. The design of CAC algorithms for mobile cellular networks is especially challenging given the limited and highly variable resources, and the mobility of users encountered in such networks. This article provides a survey of admission control schemes for cellular networks and the research in this area. Our goal is to provide a broad classification and thorough discussion of existing CAC schemes. We classify these schemes based on factors such as deterministic/stochastic guarantees, distributed/local control and adaptivity to traffic conditions. In addition to this, we present some modeling and analysis basics to help in better understanding the performance and efficiency of admission control schemes in cellular networks. We describe several admission control schemes and compare them in terms of performance and complexity. Handoff prioritization is the common characteristic of these schemes. We survey different approaches proposed for achieving handoff prioritization with a focus on reservation schemes. Moreover, optimal and near‐optimal reservation schemes are presented and discussed. Also, we overview other important schemes such as those designed for multi‐service networks and hierarchical systems as well as complete knowledge schemes and those using pricing for CAC. Finally, the paper concludes on the state of current research and points out some of the key issues that need to be addressed in the context of CAC for future cellular networks. Copyright © 2005 John Wiley & Sons, Ltd.     

Dynamic segmentation of cellular networks for improved handover performance

One of the most important initial steps, inherent in the planning procedure of cellular networks, is their segmentation in operational parts that is performed at different levels corresponding to the hierarchy and topology of the network. The major goal of this procedure is the efficient deployment of the system and management of the distributed segmented parts while minimizing the signaling overhead in the network. As we show here, it can take place even during the operational phase of the network when certain shortcomings appear. In this work, we present an approach based on graph theory for the segmentation of cellular networks at the Base Station Controller (BSC) level that achieves a significant increase in the performance of the network. In particular, with the proposed method, both the handover attempts when a mobile station is moving to a cell belonging to a different BSC as well as the corresponding handover failure rate are decreased significantly, allowing for a continuous network upgrade. Copyright © 2007 John Wiley & Sons, Ltd.     

Channelization for dynamic multi-frequency, multi-hop wireless cellular networks

Multi-hop relaying in cellular networks can greatly increase capacity and performance by exploiting the best available links to a base station. We envision an environment in which relay networks are dynamically formed when performance on the radio access network is degraded and then dissolved when the performance improves or the radio spectrum on which the relay network is operating is reclaimed. Each relay network operates on a different frequency band. Likewise, a relay network may channelize its frequency band to offer non-interfering links among the mobile nodes within a single relay network. We propose a set of algorithms used to form such relay networks on-demand. Each algorithm provides a simple and distributed frequency assignment scheme. We also propose two enhancements to improve network throughput of resulting relay networks. We evaluate these algorithms in terms of the overhead of the relay network formation. The evaluation results show that having nodes outmost from the BS initiate route discovery first is the best approach for reducing the formation overhead. The results also show that there is a large increase in throughput when using multiple frequencies in a relay network. Further, the performance of the network using multiple frequencies based on our simple frequency assignment is very close to that of a network using optimal frequency assignment.