Tat-Chee Wan

Performance evaluation of IEEE 802.15.4 wireless multi-hop networks: simulation and testbed approach

IEEE 802.15.4 for Low-Rate Wireless Personal Area Networks (LR-WPANs) standard was designed specifically for simple, low-rate, and low power applications in Wireless Sensor Networks (WSNs). It is available in ns2 simulator and numerous commercial sensor motes. In this paper a comprehensive performance evaluation of IEEE 802.15.4 using ns2 and testbed experiments is presented. The purpose is to measure the performance of the standard in various settings and compare the results obtained from simulation and realistic experiments. The performance metrics include Throughput, Packet Delivery Ratio, and Delay.

Load balancing qos multicast routing protocol in mobile ad hoc networks

Recently, multimedia and group-oriented computing become increasingly popular for the users of ad hoc networks. The study of QoS issues in MANETs is vital for supporting multimedia and real-time applications. MANETs can provide multimedia users with mobility they demand, if efficient QoS multicasting strategies were developed. In this paper, we study QoS requirements, illustrate advantages and limitations of existing QoS routing protocol and propose a QoS Multicast Routing protocol (QMR) with a flexible hybrid scheme for QoS multicast routing. The hybrid scheme contains some mechanisms that provide fix-reservation and shared-reservation bandwidth to guarantee QoS multicast routing. The proposed protocol uses forward nodes to apply QoS multicast routing from source(s) to a group of destinations and support load balancing. Analysis results show the ability of QMR to exploit residual bandwidth efficiently without effect on the reserved bandwidth and provide a balance between performance gains and design complexity.

A routing layer-based hierarchical service advertisement and discovery for MANETs

The implementation of mobile ad hoc networks (MANETs) is steadily increasing. MANETs are especially popular in locations that lack a fixed communication infrastructure. To achieve zero-configuration MANETs, as well as quick and easy access to network resources, resources must be well managed by the network. This paper proposes a hierarchical service discovery and advertisement protocol (HSDAP) implemented in the routing layer. HSDAP queries services by piggybacking service REQuest (SREQ) packets on routing packets to reduce overhead and energy consumption. We extend the cluster-based routing protocol (CBRP) to improve service management hierarchy. Simulation results show that adding service discovery and advertisement (SDA) functions to CBRP does not significantly affect overhead. SDA overhead, routing overhead, energy consumption, and SDA delay are significantly less than the extended zone routing protocol. Furthermore, SDA hit ratio of the proposed protocol is greater than 86% for various levels of mobility. The proposed HSDAP is robust and scalable.

A Survey on Analytical Modeling and Mitigation Techniques for the Energy Hole Problem in Corona-Based Wireless Sensor Network

Wireless sensor networks (WSNs) have attracted much attention in recent years. In the many-to-one WSNs, the nodes located around the sink relay the data from other sensor nodes, which depletes their energy more quickly, resulting in energy holes and hot spot areas. When an energy hole appears, data cannot be sent from other sensors to the sink even though most of the sensors still have energy. In this paper, we generally classified the schemes proposed for solving the energy hole problem. In addition, we investigated the basic mathematical modeling of network connectivity and coverage, energy consideration, and optimum width of coronas in the corona-based WSNs.

SLA-based complementary approach for network intrusion detection

Enhancing the intrusion detection system is essential to maintain user confidence in network services security. However, the threat of intruders on Internet services is prevalent. This paper proposes a distributed edge-to-edge complementary approach for intrusion detection in a DiffServ/MPLS domain. The QoS metrics are inspected at the edges routers to determine anomalous behavior in the network traffic. Consumed ratios of one-way delay variation (OWDV) and packet loss are computed to monitor service level agreement (SLA) violations. The bandwidth ratio is measured to differentiate abnormal from normal traffic as well as to detect multiple intrusions launched simultaneously. We employed SLA as a comparison scale to infer the deviation between the users consumed ratios and the predefined ratios in the SLA. Service violation occurs and intrusion may be launched when the predefined ratios are exceeded. The complementary services of DiffServ and MPLS techniques guarantee accurate measurements, whereas the complementary measurements of active and passive techniques immunize network performance against scalability limitation. Simulation results indicate that the proposed approach is capable of monitoring SLA violations and can filter out traffic of intruders who breach SLA without disturbing the normal traffic of legitimate users.

EMS-MAC

Energy efficiency is a key characteristic of modern wireless sensors. Assuming that the transceiver is the most power-consuming component of a typical sensor node, then a large advantage can be achieved at the data link layer where the medium access control (MAC) protocol controls the usage of the radio unit. Many MAC protocols have been developed for traditional wireless networks. Given that the sensor network is different from the traditional wireless network in many places, researchers are looking for a MAC protocol that is specifically designed and adapted to the sensor network. Moreover, most of the contributions in the wireless sensor network have assumed static nodes. However, some applications in the area of medical care and disaster response make use of the mobile sensor network. Thus, the present paper studies and simulates the sensor MAC (S-MAC), timeout MAC and mobility-aware S-MAC (MS-MAC) protocols in terms of their energy efficiency in different mobility situations. Furthermore, an enhancement of the MS-MAC protocol, named as enhanced MS-MAC, is introduced and simulated. The results show that this enhancement can significantly improve the energy efficiency when there is a reasonable packet delivery rate.

Indoor WLAN Monitoring and Planning Using Empirical and Theoretical Propagation Models

The wireless propagation prediction and measurement techniques are the ideas behind a successful deployment of indoor wireless local area network (WLAN). Therefore, a solution is proposed to monitor and plan the WLAN, based on the propagation prediction and measurement techniques with coloured contour visualization for IEEE 802.11 a/b/g/n standards. The solution is able to help wireless designers to visualize the WLAN signal coverage, overlapping channel interference, data rate and signal to noise ratio (SNR). The radio predictions or planning works are based on the theoretical model and the measurements or monitoring works are based on empirical model. The visualization will show the results of the WLAN monitoring and planning works with indoor wireless propagation effects from the multiple floors of the building. The experimental devices are two dual band 2.4 GHz and 5 GHz (IEEE 802.11n) access points, a 2.4 GHz (802.11g) access point, and a wireless receiver from a laptop.

Filtration model for the detection of malicious traffic in large-scale networks

Abstract This study proposes a capable, scalable, and reliable edge-to-edge model for filtering malicious traffic through real-time monitoring of the impact of user behavior on quality of service (QoS) regulations. The model investigates user traffic, including that injected through distributed gateways and that destined to gateways that are experiencing actual attacks. Misbehaving traffic filtration is triggered only when the network is congested, at which point burst gateways generate an explicit congestion notification (ECN) to misbehaving users. To investigate the behavior of misbehaving user traffic, packet delay variation (PDV) ratios are actively estimated and packet transfer rates are passively measured at a unit time. Users who exceed the PDV bit rates specified in their service level agreements (SLAs) are filtered as suspicious users. In addition, suspicious users who exceed the SLA bandwidth bit rates are filtered as network intruders. Simulation results demonstrate that the proposed model efficiently filters network traffic and precisely detects malicious traffic.

Optimized Quality of Service for Real-Time Wireless Sensor Networks Using a Partitioning Multipath Routing Approach

Multimedia sensor networks for real-time applications have strict constraints on delay, packet loss, and energy consumption requirements. For example, video streaming in a disaster-management scenario requires careful handling to ensure that the end-to-end delay is within the acceptable range and the video is received properly without any distortion. The failure to transmit a video stream effectively occurs for many reasons, including sensor function limitations, excessive power consumption, and a lack of routing reliability. We propose a novel mathematical model for quality of service (QoS) route determination that enables a sensor to determine the optimal path for minimising resource use while satisfying the required QoS constraints. The proposed mathematical model uses the Lagrangian relaxation mixed integer programming technique to define critical parameters and appropriate objective functions for controlling the adaptive QoS constrained route discovery process. Performance trade-offs between QoS requirements and energy efficiency were simulated using the LINGO mathematical programming language. The proposed approach significantly improves the network lifetime, while reducing energy consumption and decreasing average end-to-end delays within the sensor network via optimised resource sharing in intermediate nodes compared with existing routing algorithms.

On-demand flexible tiered qos scheduling algorithm for ieee 802.16j multi-hop relay networks

WiMAX is a wireless technology that provides broadband access for services having different QoS requirements and different traffic priorities. Since the QoS demands of different traffic flows vary, it is the responsibility of the medium access control (MAC) layer to schedule the traffic flows and allocate bandwidth such that the QoS requirements of each flow is satisfied. This scenario is even more complex when multi-hop relays are introduced into the network. Nonetheless, the IEEE 802.16J standard does not specify any QoS architectures or scheduling mechanisms. In this paper, we propose an On-Demand Flexible Tiered (ODFT) QoS scheduling algorithm for WiMAX Multi-hop Relay networks to guarantee the QoS demands of various applications by utilizing QoS tiers for the relay network. The ODFT (1) classifies the user requests from various wireless zones based on the zone ID and service flow types, (2) calculate the QoS weights of the service flows, (3) schedule service flows based on the calculated weights, and (4) allocate suitable bandwidth for each service flow type.