A Qualitative Resource Utilization Benchmarking for Mobile Applications

There are many mobile applications currently available on the market, which have been developed specifically for smart phones. The operating system of these smart phones is flexible enough to facilitate the high level application development. Similar to other pervasive devices, mobile phones suffer from limited amount of resources. These resources vary from the power (battery) consumption to the network bandwidth consumption. In this research the mobile resources are identified and classified. Furthermore, a monitoring approach to measure resource utilization is proposed. This monitoring tool generates traces about the resource usage which is followed by a benchmarking model which studies monitoring traces and enables users to extract qualitative information about the application from quantitative trace of resource usage.

Improving Energy Efficiency and Throughput in Heterogeneous Mobile Ad Hoc Networks

The nodes are expected to transmit at different power levels in heterogeneous mobile adhoc networks, thus leading to communication links of different length. Conventional MAC protocols that unconditionally presume that links are bi-directional and with unvarying energy distribution may not succeed or execute badly under such circumstances. Interference and signal loss resulting out of distance and fading diminish the entire throughput attained in heterogeneous networks to a greater extent. This article presents a MAC protocol, which adaptively transmits data frames using either the energy efficient nodes or a list of high data rate assistant nodes. In addition, a cross-layer based energy level on-demand routing protocol that adaptively regulates the transmission rate on basis of congestion is projected as well. Simulation results illustrate that the proposed protocols considerably diminish energy consumption and delay, and attain high throughput in contrast with the Hybrid MAC and traditional IEEE 802.11 protocols

Typology and Challenges in Developing Mobile Middleware Based Community Network Infrastructure

The evolution of mobile devices has opened new opportunities for collaboration, communication and computation on the move. Increasing device capabilities, instant connectivity, portability, rapidly reducing costs, etc. are some of the drivers for this change. Though mobile devices have lower processing power, memory capabilities compared to the stationary computing devices and deal with varying network conditions with reduced power, the demand for anywhere anytime computing is a significant driver for change. There is great interest in application development for mobile devices which caters to different needs of the users. Applications can be easily developed as complete middleware systems which can provide a great deal of abstraction for users. There is great interest in designing novel and scalable mobile middleware especially utilizing the capabilities available for collaboration and communication. This work traces the factors contributing to the proliferation of mobile communities and places the middleware for mobile community networks in a current and future perspective. The architecture for middleware based mobile community network is proposed and the challenges in implementing such a network are also discussed.

Fast Vector Quantization Encoding Algorithms for Image Compression

Vector quantization (VQ) is a well-known compression method. In the encoding phase, given a block represented as a vector, searching the closest codeword in the codebook is a time-consuming task. In this paper, two fast encoding algorithms for VQ are proposed. To reduce the search area and accelerate the search process, the first algorithm utilizes three significant features of a vector that are, the norm, and two projection angles to two projection axes. The second algorithm uses the first two features as in the first algorithm with the projection value of the vector to the second projection axe. The algorithms allow significant acceleration in the encoding process. Experimental results are presented on image block data. These results confirm the effectiveness of the proposed algorithms.

Buffer Management in Cellular IP Network using PSO

Cellular IP networks deal with the concepts of micro-mobility. Buffer management in Cellular IP networks is very crucial as its proper usage not only increases the throughput of the network but also results in the reduction of the call drops. This article proposes a model for buffer management in Cellular IP network using Particle Swarm Optimization (PSO), an evolutionary computational method often used to solve hard problems. The model considers two kinds of buffers; Gateway buffer and Base Station buffer. In the proposed two-tier model, the first tier applies a prioritization algorithm for prioritizing real-time packets in the buffer. In the second tier PSO algorithm is used on a swarm of cells in the network. PSO is applied for a given time slot, called window. In each window period the swarm can store number of packets depending on the window size and the total number of packets. The effect of various parameters e.g. number of packets, size of packets, window size, and a threshold value on buffer utilization has been studied by conducting the simulation experiments.

Performance Enhancement of Routing Protocols in Mobile Ad hoc Networks

This paper proposes to use virtual backbone structure to handle control messages in ad hoc networks. This structure is effective in reducing the overhead of disseminating control information. In the first part, the approach to build the virtual backbone on the setup phase is presented. The construction of backbone is based on the Minimum Connected Dominating Set (MCDS). The novelty is in the way on finding the MCDS. A Linear Programming approach is used to build a Minimum Dominating Set (MDS). Then, a spanning tree algorithm is applied to provide the MCDS. A theoretical analysis based on probabilistic approach is developed to evaluate the size of MCDS. Different techniques of diffusion in ad hoc networks are presented and compared. The flooding technique is simple and efficient, but it is expensive in term of bandwidth consumption and causes broadcast storm problem. Simulation results show that technique using virtual backbone performs flooding and it is compared to MPR (Multipoint Relay). The second part of this paper presents a distributed procedure to maintain the backbone when the mobility of terminals is introduced. A maintenance procedure will be executed by the node which changes its position. This procedure is distributed and guarantees the node connectivity to the backbone. The authors believe that the maintenance of the backbone with small size will be more effective. Simulation results show the performance of this procedure when mobility and scalability are considered.

Optimizing Resource Consumption for Secure Messaging in Resource Constrained Networks

Conservation of resources such as bandwidth, energy and memory are of a concern in Resource Constrained Networks (RCNs). Wireless mobile devices, especially low cost devices are stifled by the limited resources such as battery power, screen size, input, memory and processors. The low cost wireless mobile devices penetrating the developing world market demand for a cost effective messaging format that fits within the constrained wireless environment. Reduction of verbosity is considered to be one of the most effective steps in controlling the resource consumption in RCNs. This chapter presents a method for optimizing resource consumption by the use of a new messaging format with less verbosity. The proposed format is based on YAML Ain´t Markup Language (YAML), which is further enhanced with message level security specifications.

A Model for Mobile Learning Service Quality in University Environment

It is generally known that accessibility and mobility are the main barriers for effective implementation of electronic learning. However, the advent of mobile technology could be a potential solution to remove the barriers. Nevertheless, there is a lack of research that addresses the issue of mobile learning service quality in a university environment. This study aims to propose a service quality model for m-learning in a university environment. A questionnaire survey was conducted which measured ten dependent variables and three independent variables. The dependent variables were meant to measure service quality, information quality, and system quality. The dependent variables were meant to measure the causal relationship between overall learners’ perceived service quality, learner satisfaction, and learner behavioral intention to use the service in future. The findings revealed that the factors that lead to service quality of m-learning in a university environment were interface design, reliability, trust, content usefulness, content adequacy, ease of use, accessibility, and interactivity. The findings also indicates that there are causal relationships between learner satisfaction with overall service quality, and learner satisfaction with learner behavioral intention.

A Fast Image Encoding Algorithm Based on the Pyramid Structure of Codewords

This article presents a very simple and efficient algorithm for codeword search in the vector quantization encoding. This algorithm uses 2-pixel merging norm pyramid structure to speed up the closest codeword search process. The authors first derive a condition to eliminate unnecessary matching operations from the search procedure. Then, based on this elimination condition, a fast search algorithm is suggested. Simulation results show that, the proposed search algorithm reduces the encoding complexity while maintaining the same encoding quality as that of the full search algorithm. It is also found that the proposed algorithm outperforms the existing search algorithms.

Frequency Domain Equalization and Adaptive OFDM vs. Single Carrier Modulation

In the present article an attempt is made to compare multi-carrier and single carrier modulation schemes for wireless communication systems with the utilization of fast Fourier transform (FFT) and its inverse in both cases. With the assumption that in OFDM (orthogonal frequency division multiplexing), the inverse FFT transforms the complex amplitudes of the individual sub-carriers at the transmitter into time domain, the inverse operation is carried out at the receiver. In case of single carrier modulation, the FFT and its inverse are used at the input and output of the frequency domain equalizer in the receiver. Different single carrier and multi-carrier transmission systems are simulated with time-variant transfer functions measured with a wideband channel sounder. In case of OFDM, the individual sub-carriers are modulated with fixed and adaptive signal alphabets. Furthermore, a frequency-independent as well as the optimum power distribution are used. Single carrier modulation uses a single carrier, instead of the hundreds or thousands typically used in OFDM, so the peak-to-average transmitted power ratio for single carrier modulated signals is smaller. This in turn means that a SC system requires a smaller linear range to support a given average power. This enables the use of cheaper power amplifier as compared to OFDM system.[Article copies are available for purchase from InfoSci-on-Demand.com]