Zuriati Ahmad Zukarnain

The TCP fairness in WLAN: A review

In Wireless Local Area network (WLAN), fairness is an important issue. The rise of unfairness is reviewed from two aspects: per-flow and per-station. The purpose of this paper is to succinctly review recent progress in TCP fairness in WLAN. In order to better understanding of the research challenges of fairness, this article provides a detail analysis of this issue. Overall, the paper summarizes the current state of knowledge of the WLAN TCP fairness.

Cooperation stimulation mechanisms for wireless multihop networks

In wireless multihop networks such as wireless sensor networks (WSNs) and mobile ad hoc networks (MANETs), nodes have to rely on their peer neighbours in transmitting packets to intended destinations. A successful rate of communication in these networks is assured if all nodes in the network fully cooperate to relay packets for each other. However, due to the existence of nodes with various motives, cooperativeness cannot be ensured and the communication goal is not achieved. Consequently, many cooperation stimulation approaches have been proposed to address node selfishness by using, broadly, incentive-based and punishment-based approaches. These schemes consist of several components including monitoring mechanisms, that need to be optimized in order to provide effective ways to detect and manage selfish nodes in the networks. This paper summarizes existing cooperation stimulation mechanisms and discusses important issues in this field such as false judgment and node collusion, whereby the root of these kinds of problems originates from the inability to obtain accurate evaluation on the behaviour of a node.

Predetermined path of mobile data gathering in wireless sensor networks based on network layout

Data gathering is among the issues constantly acquiring attention in the area of wireless sensor networks (WSNs). There is a consistent increase in the research directed on the gains of applying mobile elements (MEs) to collect data from sensors, especially those oriented to power issues. There are two prevailing strategies used to collect data in sensor networks. The first approach requires data packets to be serviced via multi-hop relay to reach the respective base station (BS). Thus, sensors will send their packets through other intermediate sensors. However, this strategy has proven to consume high and a substantial amount of energy due to the dependency on other nodes for transmission. The second approach encompasses a ME which serves as the core element for the searching of data. This ME will visit the transmission range of each sensor to upload its data before eventually returning to the BS to complete the data transmission. This approach has proven to reduce the energy consumption substantially as compared to the multi-hop strategy. However, it has a trade-off which is the increase of delay incurred and is constrained by the speed of ME. Furthermore, some sensors may lose their data due to overflow while waiting for the ME. In this paper, it is proposed that by strategically divisioning the area of data collection, the optimization of the ME can be elevated. These derived area divisions are focused on the determination of a common configuration range and the correlation with a redundant area within an identified area. Thus, within each of these divided areas, the multi-hop collection is deployed as a sub-set to the main collection. The ME will select a centroid point between two sub-polling points, subsequently selecting common turning points as the core of the basis of the tour path. Extensive discrete-event simulations have been developed to assess the performance of the proposed algorithm. The acquired results depicted through the performance metrics of tour length and latency have determined the superior performance of the proposed algorithm in comparison to the existing strategy. In addition, the proposed algorithm maintains the energy consumption within an acceptable level.

Multi-class Bandwidth Reservation Scheme Based on Mobility Prediction for Handoff in Multimedia Wireless/Mobile Cellular Networks

Next generation of wireless cellular networks aim at supporting a diverse range of multimedia services to Mobile Terminal (MT) with guaranteed Quality of Service (QoS). The challenge is to maintain the playing continuity of multimedia streams during handoff. In this paper, a bandwidth reservation scheme based on mobility prediction is proposed, to enable high accurate prediction of next crossing cell (target cell) which a MT is going to, in order to avoid too early or over reservation resulting in a waste of resources. The amount of bandwidth to be reserved is dynamically adjusted according to (a) the current position (location) and the extrapolated direction of MT and; (b) the sector and zones of the cell. A Call Admission Control scheme (CAC) is also considered to further guarantee the QoS of real time traffic. The performance of the system is evaluated through discrete event simulation of the wireless cellular environment. Simulation results show that the proposed scheme as compared to several existing schemes is able to reduce the Handoff Call Dropping Probability (HCDP) of real time traffic and the number of terminated ongoing calls of non-real time traffic. In addition, it is efficient to reduce the number of cancelled reservation and subsequently increase the system bandwidth utilization.

A load-aware weighted round-robin algorithm for IEEE 802.16 networks

The IEEE 802.16 standard was designed to provide quality-of-service (QoS) guarantees for various classes of traffic with diverse QoS requirements. Packet-scheduling algorithms play a critical role in providing such guarantees. Weighted round robin (WRR) is one of the most commonly used scheduling algorithms, because of its simplicity and low computational overhead. However, it suffers from performance degradation under bursty traffic conditions because of the static weights used to determine packet transmissions. We propose a new packet-scheduling discipline for downlink traffic in 802.16 networks to improve performance in such situations. It dynamically determines the weight of each queue in the various classes based on the current traffic characteristics using the static WRR weight at the beginning of each base station round. The goal is not only to reduce the average delay and packet loss but also to improve average throughput. Simulations are used to evaluate the performance of the proposed algorithm load-aware weighted round robin (LAWRR), and show that it reduces average delay and packet loss, as well as it improves average throughput compared with WRR. The effectiveness of LAWRR running under fixed buffer sizes is also investigated.

An Efficient Battery Lifetime Aware Power Saving (EBLAPS) Mechanism in IEEE 802.16e Networks

The IEEE 802.16e standard is an emergent broadband wireless access technology that added the mobility feature to the original standard. This feature made battery life of an operated mobile subscribe station (MSS) a bigger challenge because an MSS is powered by a rechargeable battery. The battery lifetime mechanism has to be created in order to prolong the battery-life of an MSS. The battery lifetime-aware power saving (BLAPS) scheme has been created to prolong the battery life of an MSS by adaptively adjusting the three-sleep parameters named idle threshold, initial sleep window, and final sleep window according to the residual energy and the traffic load. However, the scheme minimized the energy consumption of the MSS at the expense of the average response delay due to the effect of the remaining energy. It also used the standard sleep mode algorithm where the MSS frequently goes to listening mode when the traffic is low which leads to the high-energy consumption. In this paper, a new energy mechanism called efficient battery life-aware power saving scheme has been proposed to enhance the parameters of BLAPS. The three-sleep parameters in BLAPS mechanism are analytically enhanced according to the downlink stochastic traffic arrival pattern of an MSS. Moreover, an improved sleep mode control algorithm has been introduced to reduce the frequent transition to listening mode in case of low traffic. The simulation has been extensively used to evaluate the proposed scheme. The results have shown that the proposed scheme outperforms the BLAPS significantly in terms of both the average response delay and the average energy consumption.

Mobility support across hybrid IP-based wireless environment: review of concepts, solutions, and related issues

The 4G or Beyond 3G wireless networks is consist of IP-based heterogeneous access networks from 3G cellular, WiFi, WiMAX to other emerging access technologies such as mesh networks. The key objective of designing the next generation wireless networks is to support of mobile subscribers. To support the mobile host in the hybrid wireless access technologies, many solutions based on network protocol stack have been proposed in the literature. In this article, after review of mobility concepts, a special attention is given to some of the mobility management methods as well as handover techniques across various wireless access networks. We have also compared the major mobility protocols in each layer for their features. Finally, some of the open issues that needed to be addressed in mobility management protocol in the next generation wireless networks are outlined.

Neighbor-Based Dynamic Connectivity Factor Routing Protocol for Mobile Ad Hoc Network

Recently, Mobile Ad hoc Networks (MANETs) have witnessed rapid development due to the low cost, diversity, and simplicity of mobile devices. Such devices can form a reliable network in a short time for use as a rescue information system after a natural disaster, where the communication infrastructure may no longer be available or accessible. Because the nodes in such a network are free to move at any time in the absence of centralized control, routing is considered to be the most challenging issue. Moreover, some routing protocols, such as Neighbor Coverage-Based Probabilistic Rebroadcast (NCPR), completely rely on preset variables, which are required to be set by the system administrator based on the scenario. Unfortunately, the setting that is proper for a specific scenario is not suitable for another scenario. In addition, some other routing protocols, such as Ad hoc On-demand Distance Vector (AODV), employ the Route REQuest message (RREQ) flooding scheme to find a path to a particular destination in the route discovery stage. Although the flooding scheme guarantees better reachability, it introduces undesirable routing overhead, which in turn leads to system performance degradation. Thus, this paper proposes a novel routing protocol, neighbor-based Dynamic Connectivity Factor routing Protocol (DCFP), that is able to dynamically probe the status of the underlying network without the intervention of a system administrator based on a novel connectivity metric, while reducing the RREQ overhead using a new connectivity factor. Furthermore, extensive simulation experiments are conducted to evaluate the performance of the proposed DCFP, where the NCPR and AODV are used as a benchmark. The proposed DCFP manages to address the need for preset variables in NCPR. Simulation results show that DCFP outperforms both NCPR and AODV in terms of end-to-end delay, normalized routing overhead, MAC collision, energy consumption, network connectivity, and packet delivery ratio due to its novel mechanism for reducing redundant RREQ.

An enhanced bandwidth reservation scheme based on road topology information for QoS sensitive multimedia wireless cellular networks

In this paper, a distributed Predictive Bandwidth Reservation scheme based on Road Topology Information (PBR-RTI), and Call Admission Control (CAC) algorithms are proposed. The goal is to reduce the Handoff Call Dropping Probability (HCDP), New Call Blocking Probability (NCBP) and to improve the bandwidth utilization. In the PRB-RTI scheme, we assume that Base Stations (BSs) are equipped with road-topology information and some Mobile Terminals (MTs) have positioning capability, while others MTs do not. The BSs estimate the probability that the MTs will enter the neighboring cells based on their factors (location, direction and speed of the MT) which are estimated by global Positioning System (GPS) and/or Received Signal Strength (RSS) and the road-topology information stored in the BSs. The BSs then compute the amount of bandwidth to be reserved, based on such estimation. Simulation results show that PRB-RTI is capable of keeping low rate for HCDP and NCBP and allocating bandwidth to new/handoff calls efficiently.

An efficient modeling and simulation of quantum key distribution protocols using OptiSystem

In this paper, we propose a modeling and simulation framework for quantum key distribution protocols using commercial photonic simulator OptiSystem™. This simulation framework emphasize on experimental components of quantum key distribution. We simulate BB84 operation with several security attacks scenario and noise immune key distribution in this work. We also investigate the efficiency of simulators inbuilt photonic components in terms of experimental configuration. This simulation provides a study to analyze the impact of experimental photonic components in quantum key distribution process.