Ali F. Almutairi

Analysis of blind data hiding using discrete cosine transform phase modulation

This paper presents an analysis for data embedding in two-dimensional signals based on DCT phase modulation. A communication system model for this data embedding scheme is developed. Closed form expressions for estimating the number of bits that can be embedded given a specific distortion measure and the probability of bit error are developed. The data embedding process is viewed as transmitting data through a binary symmetric channel with crossover error probabilities, which depends only on the power in the selected coefficients and the noise created by the signal processing operations undergone by the image.

Outage-Capacity Based Adaptive Relaying in LTE-Advanced Networks

In this paper, we investigate the benefits of relaying by comparing the transmission rates of both direct transmission (DT) and relaying. It is shown that relaying achieves SNR (signal-to-noise power ratio) gain over DT due to less pathloss, but with several relaying penalties, including a lower multiplexing gain (due to half-duplex), a lower transmit power and a higher outage requirement at each hop (due to multi-hop). We determine the conditions over which relaying outperforms DT, where the SNR gain is greater than the loss due to relaying penalties. The result is applied to the LTE-advanced networks (LTE-A) where the relay nodes (RNs) are implemented to relay information between the user equipment (UE) and the evolutional NodeB (eNB). The major difference between LTE-A and a general relay system lies in that the UE-RN hop consists of multiple frequency-division access links, while the RN-eNB hop is a point-to-point link. By investigating the effects of diversity gain on the transmission rate, we propose an outage-capacity based adaptive relaying (OCA-R) scheme to replace the conventional same-carrier relaying (SC-R). It is shown that the transmission rates of both SC-R and OCA-R are one half of the harmonic means between the outage-capacities for two hops, where the advantage of OCA-R over SC-R comes from a higher diversity gain in the RN-eNB link.

Weighting Selection in GRA-based MADM for Vertical Handover in Wireless Networks

This paper investigates the impact of weighting techniques combined with Grey Rational Analysis (GRA) when Multi-Attribute Decision Making (MADM) techniques are applied to wireless network vertical handover. The performance of the GRA algorithm is investigated with Analytical Hierarchy Process (AHP), Fuzzy AHP, Analytic Network Process (ANP), Random Weighting (RW) and Least Square weighting (LSW) techniques for background, conversational, interactive, streaming classes of services. It is observed that the use of different weighting techniques for every traffic class results in widely varying performance in terms of percentage of network selection and ranking abnormalities. It is therefore concluded that when GRA is applied to vertical network handover, careful matching among different traffic classes and proper weighting techniques should be performed in order to optimize performance in terms of judicious selection of the best network with minimal ranking abnormality.

Antenna beam pattern modulation for MIMO channels

In this paper, the antenna beam pattern modulation (ABPM) is presented as a transmission scheme which uses antenna patterns in addition to the conventional amplitude/phase modulation (APM) symbols to convey information and increase spectral efficiency. The transmitted bits per symbol period are divided into two blocks: the first block contains the antenna beam patterns and the second APM symbols. Then, the second block is mapped to an APM symbol, which is transmitted by the antenna pattern selected by the first block. The beam pattern and the transmitted symbol are detected using the maximum likelihood (ML) by the receiver, in order to de-map the block of information bits. The bit error rate (BER) performance of the proposed ABPM is evaluated over independent and identically distributed (iid) Rayleigh fading channel. The simulation results show that with appropriately designed beam patterns, the transmission scheme can provide a better performance and enhanced throughput when compared to conventional spatial modulation (SM) and APM.

Spectral efficiency improvement for LMDS systems using adaptive techniques in fading channels

Abstract Adaptive modulation, error control coding and microdiversity are well-known techniques that have been applied to wireless communication systems to overcome the fading process experienced by the transmitted signal. In this paper, we investigate the throughput returns due to the employments of various combinations of adaptive modulation, adaptive coding, and microdiversity in a broadband fixed wireless access cellular system. The results indicate that using adaptive modulation, coding, and maximal ratio combining (MRC) yields significant enhancements in spectral efficiency of the system. Second order selection combining has almost the same performance of MRC.

GPRS/EDGE/3G/HSDPA networks performance measurements in the State of Kuwait

GPRS, EDGE, 3G and HSDPA are wireless data services that are deployed by Mobile operators to provide higher data rate. This paper provides a set of measurements that are used to evaluate, from user perspective, these types of data services in the State of Kuwait. The Measurements are taken in different areas of Kuwait. Measurements show that HSDPA is the best wireless data connection offered by the mobile operators in the state of Kuwait. The measurements are based on measuring the Quality of Service (QoS) experienced by one mobile user running applications such as FTP and WWW on laptops connected to GPRS, EDGE, 3G, HSDPA networks.

Adaptive distribution-based handover scheme for cellular communication networks

In this paper, we propose a new Generalized Distribution-Based Handover (DBHO) to deal with the inefficient utilization of spectral resources due to the non-uniform cell loads. The DBHO scheme is different from the existing adaptive schemes since it uses a new criterion to initiate handover when moving from/to a congested cell. Two risk factors are used to dynamically change handover boundaries according to the distribution of traffic loads. This controls the handover initiation process such that a user in a congested cell that is moving to a free cell is allowed to initiate a handover to a new cell earlier, as long as the signal received from the target cell is higher than a certain threshold. While delaying the handover initiation process for a user moving in the opposite direction, as long as the signal received from the serving cell is not lower than a certain threshold. Our results show a substantial reduction in the handover and call dropouts rates. Our scheme is complementary to the existing adaptive schemes proposed in the literature. The proposed scheme also gives cellular system designers a new tool to optimize the overall network performance by initiating handovers based on the traffic intensities. Frequent handovers increase the load on switching networks, which consequently degrades the Quality of Service (QoS). Existing handover schemes usually use parameters such as the received signal strength for initiating a handover with some additional measurements to reduce unnecessary handovers and call dropouts. These schemes perform well when cell loads are somewhat evenly distributed, but fail to account for nonuniform traffic, as is often the case in microcells. Hence, it is desirable to design efficient handover schemes to avoid unnecessary handovers, reduce call dropouts and yet dynamically adapt to the variation of traffic among cells. In this paper, we present a new adaptive handover scheme that dynamically changes the handover boundaries to balance cell loads and to effectively reduce the average number of handovers. Copyright

Performance of different weighting techniques with DIA MADM method in heterogeneous wireless networks

The paper investigates the optimum pairing of attribute weighting techniques used with Distance to Ideal Alternative (DIA) selection in Multi-Attribute Decision Making (MADM) applied to wireless network vertical handover. The performance of the DIA algorithm is investigated with Analytical Hierarchy Process (AHP), Fuzzy AHP, Analytic Network Process (ANP), Random Weighting (RW) and Least Squared weighting (LSW) techniques for different user service classes including background, conversational, interactive, streaming traffic. It is found that the use of different weighting techniques for every traffic class results in widely varying performance figures. Comparative numerical results are given to quantify the system performance in terms of best network selection and ranking abnormalities. The paper findings provide guidelines for selecting weighting techniques for each traffic class in order to achieve ideal network selection with minimal ranking abnormality.

Performance investigation using different software of Dynamic Source Routing in ad-hoc networks

Ad-hoc network is a self organizing network that consists of mobile nodes. Each node acts as a router that forwards the data to other nodes in the network. Ad hoc routing protocols are affected by mobility of the nodes and network scalability. In this paper, the performance of Dynamic Source Routing (DSR) is studied through simulation, using NS2, and QualNet. The effects of mobility and network scalability for different network scenarios will be investigated. The performance results show that there exist significant divergences, among the results obtained by the two software packages, when the network scaled to a large number of nodes or the traffic sources increased. An analytical model to compute the number of route errors is presented. We expect that these results will be very helpful to engineers in designing ad-hoc routing protocols, and their decision about the type of network and the appropriate software tool they will use.

A genetic algorithm approach for multi-attribute vertical handover decision making in wireless networks

Mobile terminals can typically connect to multiple wireless networks which offer varying levels of suitability for different classes of service. Due to the changing dynamics of network attributes and mobile users’ traffic needs, vertical handovers across heterogeneous networks become highly desirable. Multiple attribute decision making (MADM) techniques offer an efficient approach for ranking competing networks and selecting the best one according to specific quality of service parameters. In this paper, a genetic algorithm (GA) is applied to optimize network attributes’ weighting by emphasizing ranking differences among candidate networks, thereby aiding correct decision making by reducing unnecessary handovers and ranking abnormalities. The performance of the proposed GA-based vertical handover is investigated with typical MADM techniques including Simple Additive Weighting (SAW) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). The results show that the proposed GA-based weight determination approach reduces the abnormality observed in the conventional SAW and TOPSIS techniques substantially. The results of this paper will help ensuring the application of MADM methods to more dynamic and challenging decision making problems encountered in wireless network.