Modeling and analysis of mobility management state of packet-switched (PS) services in GPRS

There has been an increasing demand for wireless data services due to the popularity of Internet services and circuit-switched (CS) systems are not appropriate for accommodating bursty data traffic. The wireless data services can be efficiently supported in the packet-switched (PS) system and General Packet Radio Service (GPRS) is a representative PS system which is being serviced widely. In GPRS, three mobile station (MS) mobility management states, i.e., idle, ready, and standby are defined in order to accommodate bursty traffic characteristics of data services, and thus, GPRS results in efficient management of radio resources and signaling networks. In order to analyze the performance of GPRS mobility management, we develop an analytical model to derive the steady-state probability of the MS states, which is essential in the performance analysis. The analytical model is validated by using a simulation model. The effect of various input parameters on the steady-state probability and the effect of variances of cell residence time, RA residence time, and packet transmission time are analyzed. Then, location update signaling and paging signaling loads are investigated based on the steady-state probability. Our study provides guideline for proper selection of PS system parameters and can be used to analyze the performance of mobility management schemes for PS systems.     

An integrated traffic model for multimedia wireless networks

Multimedia wireless networks are seen today as one of the key factors for the success of the global communication infrastructure in the near future. Such networks will have to handle a range of heterogeneous traffic classes with different QoS requirements. Their design, planning and control must be supported by suitable traffic models capable of dealing with a new set of constraints where QoS management and mobility play an important role.This paper proposes a traffic model for a cellular multimedia wireless network characterized by the integration of mobility and traffic management aspects. User mobility is modeled through a Markov renewal process, which allows for non-exponential cell residence times and may restrict the user mobility to existent paths in the system. A Markov-modulated fluid process is used to describe the changes in the bandwidth requirements of each mobile over the duration of its calls, including the periods where the mobile is inactive (without call).Based on the proposed model, the number of mobiles per class of traffic in a cell and the handoff processes are characterized. System performance results, such as new and handoff call blocking probabilities, for network planning are derived. Also, the distribution of the required capacity in a short time interval for network control is obtained. Simulations were carried out to validate the analytical results. The comparisons have shown that the integrated model may be regarded as a good basis to build useful teletraffic engineering tools for multimedia wireless networks.     

Group registration with distributed databases for location tracking in 3G wireless networks

The increase of subscribers in wireless networks has led to the need for efficient location tracking strategies. Location tracking is used to keep track of a Mobile Terminal (MT). The network retains the Registration Area (RA), where the MT last updated its location, so when an incoming call arrives for the MT, the network with the help of a location tracking strategy can find the area where the MT resides and then deliver the call. In this paper, we introduce a 2-level distributed database architecture combined with the Group Registration (GR) location tracking strategy to be used in 3G wireless networks. The GR strategy reduces the location management total cost, by updating the location of MTs in an RA with a single route response message to the HSS (Home Subscriber Server). More specifically, the IDs of the MTs newly moving into an RA are buffered and sent to the HSS for location updating in the route response message of the next incoming call to any MT in the RA. An analytical model is developed and numerical results are presented. It is shown that the GR strategy integrated with a 2-level distributed databases architecture in 3G networks can achieve location management cost reduction compared to costs of the distributed databases without the GR strategy and the GR strategy without distributed databases. Moreover, the proposed strategy results in small call delivery latency.     

Cross-layer radio resource management in integrated WWAN and WLAN networks

This paper proposes a mobility adaptive network selection scheme in the context of wireless wide area network (WWAN) and wireless local area network (WLAN) radio access technologies (RATs) that supports both real-time (RT) and non-real-time (NRT) service classes. Physical layer information based call admission control (CAC) is considered for the two RATs to enforce service specific QoS requirements. The effectiveness of the cross-protocol-layer information for radio resource management (RRM) in integrated WWAN and WLAN networks is assessed analytically for individual service classes in a multi-service environment using the theory of Markov chains. The impact of non-uniform user and mobility distributions due to the existence of hotspot in the macro-cell area and the effect of network selection parameter measurement errors on the RRM performance are also evaluated. Numerical results show that the proposed network selection scheme minimizes the rate of unnecessary vertical handoffs, thereby providing stable communication without degrading the call blocking probability and call outage probability performance metrics.     

An efficient metric-based (EM-B) location management scheme for wireless cellular networks

In the current era, the wireless cellular network is gaining much attention in the network mobility for qualitative service. Towards enhancing the QoS and narrowing the dilemma of network management (location management) an efficient metric-based location management technique is introduced in this paper to capture the current location of mobile subscribers. The attributes of this technique are based on metrics calculation and location management message routing path determination. First, the current mobile switching center will calculate the shortest metric-based path between current and master (previous) location of mobile terminals (user), thereafter it performs the location management procedure through the optimal suggested path by the mobile switching center. This proposed technique will reduce the signaling cost, registration delay, call setup delay, network overheads and total location management cost. The proposed analytical model checks the scalability and effectiveness of proposed system over certain attributes and a comparison is made with the existing available techniques.     

异构无线网络多网资源优化管理研究

针对异构无线网络多网协同的特点,从分析多个无线网络共存的资源管理优化体制构建思想出发,建立了新的异构无线网络资源统一管理优化模型,实现了协同信息的控制和管理,同时保证了异构数据呼叫业务的服务质量,解决了多网间资源管理优化问题。首先,该模型在对呼叫服务请求做优化决策时,不仅考虑了本网络服务域的可用资源、服务请求的速率以及本系统的长期收益,同时也考虑了其他网络服务域的整体长期收益;其次,通过对所提出的基于异构无线网络多网资源优化管理模型的性能进行理论分析,得到其重要服务质量参数——新呼叫阻塞率;最后,通过仿真比较可以看出,通过该模型获得的优化决策策略能充分利用异构无线网络中各个网络域的资源,不仅提高了资源的利用率,而且在提高网络整体长期收益的同时,也保证了移动服务的服务质量。与资源完全共享算法相比,本方法降低了新呼叫阻塞率。理论分析和实验证明了异构无线网络资源域间资源优化管理方法的有效性、适应性。     

Implementation of call admission control scheme in next generation mobile communication networks using particle swarm optimization and fuzzy logic systems

In the present and next generation wireless networks, cellular system remains the major method of telecommunication infrastructure. Since the characteristic of the resource constraint, call admission control is required to address the limited resource problem in wireless network. The call dropping probability and call blocking probability are the major performance metrics for quality of service (QoS) in wireless network. Many call admission control mechanisms have been proposed in the literature to decrease connection dropping probability for handoffs and new call blocking probability in cellular communications. In this paper, we proposed an adaptive call admission control and bandwidth reservation scheme using fuzzy logic control concept to reduce the forced termination probability of multimedia handoffs. Meanwhile, we adopt particle swarm optimization (PSO) technique to adjust the parameters of the membership functions in the proposed fuzzy logic systems. The simulation results show that the proposed scheme can achieve satisfactory performance when performance metrics are measured in terms of the forced termination probability for the handoffs, the call blocking probability for the new connections and bandwidth utilization.     

支持QoS的无线传感器网络数据聚合技术研究

结合数据聚合技术的特点,通过分析现有无线传感器网络的QoS研究,提出了数据聚合的三个QoS度量指标,即网络生命周期、数据时延、数据质量,讨论并分析了保证这些数据聚合QoS指标的关键技术,对于进一步深入研究无线传感器网络的数据聚合技术具有比较重要的参考价值.     

Complexity results on labeled shortest path problems from wireless routing metrics

Metrics to assess the cost of paths through networks are critical to ensuring the efficiency of network routing. This is particularly true in multi-radio multi-hop wireless networks. Effective metrics for these networks must measure the cost of a wireless path based not only on traditional measures such as throughput, but also on the distribution of wireless channels used. In this paper, we argue that routing metrics over such networks may be viewed as a class of existing shortest path problems, the formal language constrained path problems.On this basis, we describe labeled path problems corresponding to two multi-radio wireless routing metrics: Weighted Cumulative Expected Transmission Time (WCETT), developed by Draves et al., and Metric for Interference and Channel-switch (MIC), developed by Yang et al. For the first, we give a concise proof that calculating shortest WCETT paths is strongly NP-Complete for a variety of graph classes. We also show that the existing heuristic given by Draves et al. is an approximator. For the second, we show that calculating loop-free (simple) shortest MIC paths is NP-Complete, and additionally show that the optimization version of the problem is NPO PB-Complete. This result implies that shortest simple MIC paths are only poorly approximable in the worst case.Furthermore, we demonstrate how the polynomial-time algorithm for shortest MIC paths is derivable from an existing language constrained shortest path algorithm. We use this as a basis to exhibit the general utility of viewing multi-channel wireless routing metrics as labeled graph problems, and discuss how a class of related polynomial-time computable metrics are derivable from this algorithm.     

Cooperative radio resource management framework for future IP-based multiple radio access technologies environment

Heterogeneity and convergence are two distinctive connotations of future wireless networks emanated from International Telecommunications Union (ITU)’s vision of Optimally Connected, Anywhere, Anytime. Multiple access networks, multiple terminals and multiple services are expected to converge in a manner where heterogeneity can be exploited to realize this ultimate goal. This raises the importance of radio resource management (RRM) for a multiple radio access technologies (multi-RAT) environment, where coalitions of heterogeneous access networks are each connected to a common Internet Protocol (IP)-based core network. In this article, we develop a cooperative RRM framework for future IP-based multi-RAT environment to coordinate better utilization of radio resources in an opportunistic yet altruistic manner. We motivate the importance of cooperation which can exploit heterogeneity as an enabler to improve system capacity and quality of service (QoS) of users. We exemplify the proof of concept based on a heterogeneous multiple access points (multi-AP) wireless local area network (WLAN) and argue that our technology agnostic approach is readily applicable to future IP-based multi-RAT environment. We demonstrate that our cooperative RRM framework benefits from the unified actions of joint optimization and results in a QoS-balanced system by enabling different functional entities to form synergies and multiple access networks to interact. We further show that a QoS-balanced system has salient traits of providing statistical QoS guarantee to support demanding multimedia applications while maximizing overall system capacity. Consequently, we advocate the notion of QoS balancing as criterion to quantify the state of balance in future IP-based multi-RAT environment.     

Using artificial intelligence in routing schemes for wireless networks

For the latest 10 years, many authors have focused their investigations in wireless sensor networks. Different researching issues have been extensively developed: power consumption, MAC protocols, self-organizing network algorithms, data-aggregation schemes, routing protocols, QoS management, etc. Due to the constraints on data processing and power consumption, the use of artificial intelligence has been historically discarded. However, in some special scenarios the features of neural networks are appropriate to develop complex tasks such as path discovery. In this paper, we explore the performance of two very well-known routing paradigms, directed diffusion and Energy-Aware Routing, and our routing algorithm, named SIR, which has the novelty of being based on the introduction of neural networks in every sensor node. Extensive simulations over our wireless sensor network simulator, OLIMPO, have been carried out to study the efficiency of the introduction of neural networks. A comparison of the results obtained with every routing protocol is analyzed. This paper attempts to encourage the use of artificial intelligence techniques in wireless sensor nodes.     

Assessment and improvement of quality of service in wireless networks using fuzzy and hybrid genetic-fuzzy approaches

Fuzzy and hybrid genetic-fuzzy approaches were used to assess and improve quality of service (QoS) in simulated wireless networks. Three real-time audio and video applications were transmitted over the networks. The QoS provided by the networks for each application was quantitatively assessed using a fuzzy inference system (FIS). Two methods to improve the networks’ QoS were developed. One method was based on a FIS mechanism and the other used a hybrid genetic-fuzzy system. Both methods determined an optimised value for the minimum contention window (CW _min) in IEEE 802.11 medium access control (MAC) protocol. CW _min affects the time period a wireless station waits before it transmits a packet and thus its value influences QoS. The average QoS for the audio and video applications improved by 42.8% and 14.5% respectively by using the FIS method. The hybrid genetic-fuzzy system improved the average QoS for the audio and video applications by 35.7% and 16.5% respectively. The study indicated that the devised methods were effective in assessing and significantly improving QoS in wireless networks.     

A fair resource allocation protocol for multimedia wireless networks

Wireless networks are expected to support real-time interactive multimedia traffic and must be able, therefore, to provide their users with quality-of-service (QoS) guarantees. Although the QoS provisioning problem arises in wireline networks as well, mobility of hosts and scarcity of bandwidth makes QoS provisioning a challenging task in wireless networks. It has been noticed that multimedia applications can tolerate and gracefully adapt to transient fluctuations in the QoS that they receive from the network. The additional flexibility afforded by the ability of multimedia applications to tolerate and adapt to transient changes in QoS can be exploited by protocol designers to significantly improve the overall performance of wireless systems. This paper presents a fair resource allocation protocol for multimedia wireless networks that uses a combination of bandwidth reservation and bandwidth borrowing to provide network users with QoS in terms of guaranteed bandwidth, call blocking, and call dropping probabilities. Our view of fairness was inspired by the well-known max-min fairness allocation protocol for wireline networks. Simulation results are presented that compare our protocol to similar schemes.     

Hierarchical management protocol for constructing a QoS communication path in wireless Ad Hoc networks

An Ad Hoc network consists of mobile hosts that can dynamically construct a wireless network without base stations. Due to the limited communication range, a source host usually needs other hosts to relay messages to the destination in a multi-hop manner. Consequently, establishing a routing path from the source to the destination is a basic requirement for providing communication service between any pair of mobile hosts. This study proposes a two-level management approach for efficiently constructing and maintaining a QoS routing path in Ad Hoc wireless networks, significantly reducing the quantity of control packets. In the first phase, the mobile hosts are partitioned into a number of complete graphs, each represented by a Supernode managed by an agent. The Ad Hoc network topology is thus transformed to an Agent-based Graph (AG). In the second phase, some agents of a larger degree than neighboring agents are selected as core nodes. The core nodes then virtually construct a Core Graph (CG). The proposed two-level hierarchical management and bandwidth-looking-ahead technologies can efficiently establish and maintain a QoS communication path at a low control packet cost. Simulation results indicate that the proposed management model significantly reduces the number of control packets in areas with very large numbers of mobile hosts.     

Service level agreements (SLAs) parameter negotiation between heterogeneous 4G wireless network operators

We are currently witnessing a growing interest of network operators to migrate their existing 2G/3G networks to 4G technologies such as long-term evolution (LTE) to enhance the user experience and service opportunities in terms of providing multi-megabit bandwidth, more efficient use of radio networks, latency reduction, and improved mobility. Along with this, there is a strong deployment of packet data networks such as those based on IEEE 802.11 and 802.16 standards. Mobile devices are having increased capabilities to access many of these wireless networks types at the same time. Reinforcing quality of service (QoS) in 4G wireless networks will be a major challenge because of varying bit rates, channel characteristics, bandwidth allocation and global roaming support among heterogeneous wireless networks. As a mobile user moves across access networks, to the issue of mapping resource reservations between different networks to maintain QoS behavior becomes crucial. To support global roaming and interoperability across heterogeneous wireless networks, it is important for wireless network operators to negotiate service level agreement (SLA) contracts relevant to the QoS requirements. Wireless IP traffic modeling (in terms of providing assured QoS) is still immature because the majority of the existing work is merely based on the characterization of wireless IP traffic without investigating the behavior of queueing systems for such traffic. To overcome such limitations, we investigate SLA parameter negotiation among heterogeneous wireless network operators by focusing on traffic engineering and QoS together for 4G wireless networks. We present a novel mechanism that achieves service continuity through SLA parameter negotiation by using a translation matrix, which maps QoS parameters between different access networks. The SLA matrix composition is modeled analytically based on the G/M/1 queueing system. We evaluate the model using two different scheduling schemes and we derive closed form expressions for different QoS parameters for performance metrics such as packet delay and packet loss rate. We also develop a discrete event simulator and conduct a series of simulation experiments in order to understand the QoS behavior of corresponding traffic classes.     

Service Adaptability in Multimedia Wireless Networks

Next-generation wireless communication systems aim at supporting wireless multimedia services with different quality-of-service (QoS) and bandwidth requirements. Therefore, effective management of the limited radio resources is important to enhance the network performance. In this paper, we propose a QoS adaptive multimedia service framework for controlling the traffic in multimedia wireless networks (MWN) that enhances the current methods used in cellular environments. The proposed framework is designed to take advantage of the adaptive bandwidth allocation (ABA) algorithm with new calls in order to enhance the system utilization and blocking probability of new calls. The performance of our framework is compared to existing framework in the literature. Simulation results show that our QoS adaptive multimedia service framework outperforms the existing framework in terms of new call blocking probability, handoff call dropping probability, and bandwidth utilization.      

Dynamic radio resource allocation for 3G and beyond mobile wireless networks

Next generation of wireless cellular networks aim at supporting a diverse range of multimedia services to mobile users with guaranteed quality of service (QoS). Resource allocation and call admission control (CAC) are key management functions in future 3G and 4G cellular networks, in order to provide multimedia applications to mobile users with QoS guarantees and efficient resource utilization. There are two main strategies for radio resource allocations in cellular wireless networks known as complete partitioning (CP) and complete sharing (CS). In this paper, theses strategies are extended for operation in 3G and beyond network. First, two CS-based call admission controls, referred to herein as queuing priority call admission control (QP-CAC) and hybrid priority call admission control (HP-CAC), and one CP-based call admission control referred to as complete partitioning call admission control (CP-CAC) are presented. Then, this study proposes a novel dynamic procedure, referred to as the dynamic prioritized uplink call admission control (DP-CAC) designed to overcome the shortcomings of CS and CP-based CACs. Results indicate the superiority of DP-CAC as it is able to achieve a better balance between system utilization, revenue, and quality of service provisioning. CS-based algorithms achieve the best system utilization and revenue at the expense of serious unfairness for the traffic classes with diverse QoS requirements. DP-CAC manages to attain equal system utilization and revenue to CS-based algorithms without the drawbacks in terms of fairness and service differentiation.     

The impact of topology on energy consumption for collection tree protocols: An experimental assessment through evolutionary computation

The analysis of worst-case behavior in wireless sensor networks is an extremely difficult task, due to the complex interactions that characterize the dynamics of these systems. In this paper, we present a new methodology for analyzing the performance of routing protocols used in such networks. The approach exploits a stochastic optimization technique, specifically an evolutionary algorithm, to generate a large, yet tractable, set of critical network topologies; such topologies are then used to infer general considerations on the behaviors under analysis. As a case study, we focused on the energy consumption of two well-known ad hoc routing protocols for sensor networks: the multi-hop link quality indicator and the collection tree protocol. The evolutionary algorithm started from a set of randomly generated topologies and iteratively enhanced them, maximizing a measure of “how interesting” such topologies are with respect to the analysis. In the second step, starting from the gathered evidence, we were able to define concrete, protocol-independent topological metrics which correlate well with protocols’ poor performances. Finally, we discovered a causal relation between the presence of cycles in a disconnected network, and abnormal network traffic. Such creative processes were made possible by the availability of a set of meaningful topology examples. Both the proposed methodology and the specific results presented here – that is, the new topological metrics and the causal explanation – can be fruitfully reused in different contexts, even beyond wireless sensor networks.     

On Minimizing the Cost of Location Management in Mobile Environments

A mobile host typically has a home agent that maintains a registry of its current location. This registry is normally updated every time a host changes its current network. The update cost could be reduced using a two-tier update process in which a registry is updated using special agents, called proxy agents. We study the problem of selecting proxy agents to minimize the cost of search associated with this two-tier update approach. We show that the problem can be formulated as p-center or p-median finding problems. We focus on the p-center formulation. Due to the intractability of the problem, we introduce a distributed strategy to solve the general problem and show that it yields an approximate solution for arbitrary networks. We present an implementation of the distributed strategy that produces an optimal solution for ring networks. We prove that the optimal solution for rings is fault tolerant and resilient to topology changes.