Energy-efficient Scalable Self-organizing Routing for Wireless Mobile Networks

The instant deployment without relying on an existing infrastructure makes the mobile ad hoc networks (MANET) an attractive choice for many dynamic situations. An efficient MANET protocol may be applied to other important emerging wireless technologies such as wireless mesh and sensor networks. This chapter proposes a hierarchical routing scheme that is scalable, energy-efficient, and self-organizing. This chapter presents a new algorithm: the Dynamic Leader Set Generation (DLSG). This algorithm dynamically selects leader nodes based on traffic demand, locality, and residual energy level, and de-selects them based on residual energy. Therefore, energy consumption and traffic load are distributed throughout the network. The network also reorganizes itself surrounding the dynamically selected leader nodes. Time, space, and message complexities are formally analyzed; implementation issues are also addressed. Incorporating the IEEE 802.11 medium access control mechanism including the power saving mode, performance evaluation is carried out by simulating DLSG and four existing hierarchical routing algorithms. It shows that DLSG successfully extends network lifetime by 20-50% while achieves a comparable level of network performance.

Subscription Policy Control Framework for IMS-Based Networks

The Policy and Charging Control (PCC) architecture was firstly introduced in the 3GPP’s Release 7. However, the PCC has its problems. The main problems include the incapability of performing policy control with consideration of subscriber profiles and missing specification on how to organize and express the policy information. In addition, no policy control at application session establishment stage also contributes to its imperfectness. In this paper, the authors propose a subscription-based policy control framework that implements a subscription-centered approach for policy control and to enable flexible policy definitions based on the subscriber’s profile at the application level. The framework also provides functionalities of organizing the subscription data, identifying the policy, regulating the policy control process, interpreting, managing and enforcing the corresponding policies. The main objective is to qualify the subscribers and thus, enhance the network customization through defining flexible policies based on policy control requirements for different subscribers.

A GPS Based Deterministic Channel Allocation for Cellular Network in Mobile Computing

The scarcity of the radio channel is the main bottleneck toward maintaining the quality of service (QoS) in a mobile cellular network. As channel allocation schemes become more complex and computationally demanding, alternative computational models that include knowledge-based algorithms and provide the means for faster processing are becoming a topic of research interest. An efficient deterministic technique, capable of handling channel allocation problems, is introduced as an alternative. The proposed model utilizes the Global Positioning System (GPS) data for tracing the hosts’ likely movements within and across the cells and allocates the channels to the mobile devices accordingly. The allocation of the channels to the mobile hosts is deterministic in the sense that the decision of the channel allocation is based on the realistic data received from the GPS about the hosts’ movements. The performance of the proposed technique has been evaluated by conducting the simulation experiments for the two parameters—call blocking and handoff failures. Also, a comparison of the proposed model with an earlier model has been carried out to estimate the effectiveness of the proposed technique. Experimental results reveal that the proposed technique performs better and is more realistic as well.

On Demand Bandwidth Reservation for Real-Time Traffic in Cellular IP Network using Particle Swarm Optimization

Cellular IP network deals with micro mobility of the mobile devices. An important challenge in wireless communication, especially in cellular IP based network, is to provide good Quality of Service (QoS) to the users in general and to the real-time users (users involved in the exchange of real-time packets) in particular. Reserving bandwidth for real time traffic to minimize the connection drop (an important parameter) is an activity often used in Cellular IP network. Particle Swarm Optimization (PSO) algorithm simulates the social behavior of a swarm or flock to optimize some characteristic parameter. PSO is effectively used to solve many hard optimization problems. The work, in this paper, proposes an on demand bandwidth reservation scheme to improve Connection Dropping Probability (CDP) in cellular IP network by employing PSO. The swarm, in the model, consists of the available bandwidth in the seven cells of the cellular IP network. The anytime bandwidth demand for real-time users is satisfied by the available bandwidth of the swarm. The algorithm, used in the model, searches for the availability of the bandwidth and reserves it in the central cell of the swarm. Eventually, it will allocate it on demand to the cell that requires it. Simulation experiments reveal the efficacy of the model.

Slot Allocation Algorithms for Minimizing Delay in Alarm-Driven WSNs Applications

Energy-efficiency and latency requirements in alarm-driven Wireless Sensor Networks often demand the use of TDMA protocols with special features such as cascading of timeslots, in a way that the sensor-to-sink delay bound can stay below the duration of a single frame. However, this single TDMA frame should be as small as possible. The results presented in this paper, point to the conclusion that a largest-distances-first strategy can achieve the smallest single frame sizes, and also the lowest frame size variations. A quite simple distributed version of this algorithm is presented, which obtains the same results of its centralized version. Simulations also show that this discipline presents the best results in terms of sensor-to-sink slot distance, even if they require a few more slots than breadth-first in multi-frame scenarios.

Comparison of Policies for Epidemic Broadcast in DTNs under Different Mobility Models

The broadcast diffusion of messages in Delay Tolerant Networks (DTNs) is heavily dependent on nodes mobility, since protocols must rely on contact opportunities among devices to diffuse data. This work is a first effort to study how the dynamics of nodes affect both the effectiveness of the broadcast protocols in diffusing data, and their efficiency in using the network resources. The paper describes three control mechanisms. The mechanisms characterize a family of protocols able to achieve some awareness about the surrounding environment, and to use this knowledge in order to keep the broadcast overhead low, while ensuring high node coverage. Simulation results allow to identify the winning mechanisms to diffuse messages in DTNs under different conditions.

Fourier-Based Assessment Strategies for Simulated Ad Hoc Networks

An ad hoc network comprises mobile devices with limited computing and energy resources together with wireless communication, which have to cooperate to provide networking services. This communication scenario presents many specific challenges that make ad hoc networks very different from traditional wired and wireless data networks. It makes classical approaches for network analysis insufficient. To deal with the design, implementation and test of this innovative communication paradigm, simulation techniques are of primary importance, since they allow to specify the level of detail of the simulated model. At the same time, the complex interaction among different entities make the performance evaluation of real ad hoc systems through simulation very hard. This chapter discusses traditional simulation strategies for ad hoc networks, highlighting their limits, drawbacks and possible overcoming. It presents efforts of the research community in improving the quality of simulation analysis according to different aspects, such as metrics definition, model design and simulation tools extensions. Then, the chapter focuses its attention on the benefits that the Discrete Fourier Transform analysis can produce if it is applied on simulation data. It describes a detailed methodology to gather and elaborate simulation measurements in order to avoid loss of information on rare events that occur in simulations. The presented methodology gets advantages (such as simplicity and flexibility) from simulative investigation approaches and, at the same time, offers a new analysis tool suitable for both protocol debugging and system performances evaluation. In fact, it transfers time-dependent measurements into the frequency domain, allowing to point out the occurrence of events which take place only under particular conditions and to detect occasional misbehaviors of the system.

Strategic Scenarios for Fixed-Mobile Convergence

This study demonstrates that an integrated operator can benefit from cost savings, customer retention and prevention of revenue erosion by having a fixed-mobile convergence (FMC) migration strategy including introduction of advanced service packages. This development is driven by increasing importance of mobile network capabilities and services, as well as the decreasing gap between fixed and mobile systems, in terms of technological models and prices, making FMC both requested by the market and commercially feasible to provide. FMC is expected to offer benefits for network and service operators as well as businesses and consumers. The authors have analyzed the operator’s dilemma on proper migration strategy in exploiting the benefits of cost savings and generating new revenues, but exposing oneself to the risk of substitution effects among its fixed and mobile products. They provide quantitative comparison of some strategic scenarios utilizing techno-economic case study methodology in modeling an integrated operator business in a Western European context.

Fairness Analysis and Improvement of Transport Layer Protocols

The article presents a comparison of fairness properties of different congestion control schemes. It is hard to investigate the various protocol mechanisms implemented in transport protocols; therefore a simulator called SimCast is developed for the analysis of fairness characteristics of transport protocols as well as a network traffic generator and measurement tool called SimTest. This article presents the operation and basic properties of these evaluation systems together with some simulation and measurement results. The article also presents a fairness based bandwidth control mechanism, called the Balancer method, which optimizes resource allocation of busy servers with large amount of outgoing traffic. The efficiency of this control method is presented through simulation results.

A Survey on Classical Teletraffic Models and Network Planning Issues for Cellular Telephony

Air pollution is an important environmental issue that has a direct effect on human health and ecological balance. Factories, power plants, vehicles, windblown dust and wildfires are some of the contributors to pollution. Reasonable simulation tools exist for evaluating large scale sensor networks; however, they fail to capture significant details of node operation or practical aspects of wireless communication. Real life testbeds capture the realism and bring out important aspects for further research. In this paper, we present an implementation of a wireless sensor network testbed for automatic and real-time monitoring of environmental pollution for the protection of public spaces. The paper describes the physical setup, the sensor node hardware and software architecture for “anytime, anywhere” monitoring and management of pollution data through a single, Web-based graphical user interface. The paper presents practical issues in the integration of sensors, actual power consumption rates and develops a practical hierarchical routing methodology.