Dr. Mazlan Abbas

An integrated multi-tier, multi-hop WiMAX-WiFi network is seen as a promising solution to provide fast and low cost broadband access to places where the wired infrastructure is not ready or is too expensive. This paper investigates the potentials of deploying such network in rural Malaysia. The role of IEEE802.16 (WiMAX) WMAN technology is basically to provide backhaul support i.e. carry traffic from various access nodes to the gateway and hence the Internet, while the IEEE802.11 WLAN (WiFi)… Tunjukkan lagi

An integrated multi-tier, multi-hop WiMAX-WiFi network is seen as a promising solution to provide fast and low cost broadband access to places where the wired infrastructure is not ready or is too expensive. This paper investigates the potentials of deploying such network in rural Malaysia. The role of IEEE802.16 (WiMAX) WMAN technology is basically to provide backhaul support i.e. carry traffic from various access nodes to the gateway and hence the Internet, while the IEEE802.11 WLAN (WiFi) provides access service to the end users. This paper provides some insights on the capacity and coverage and performance of the proposed architecture. Its capability to provide multimedia services is also investigated using a representative village scenario in Malaysia. Tunjukkan kurang

Multi-tier, multi-hop network architecture with integrated WiMAX-WiFi radio interfaces offers an alternative means of delivering broadband wireless access services to mass users rapidly and cost-effectively. Besides providing wireless backhaul in places where wired backhaul infrastructure is not ready or too expensive, such architecture can also take advantage of the complementary features offered by the two diverse technologies. Such architecture however inspires a wide range of complex and… Tunjukkan lagi

Multi-tier, multi-hop network architecture with integrated WiMAX-WiFi radio interfaces offers an alternative means of delivering broadband wireless access services to mass users rapidly and cost-effectively. Besides providing wireless backhaul in places where wired backhaul infrastructure is not ready or too expensive, such architecture can also take advantage of the complementary features offered by the two diverse technologies. Such architecture however inspires a wide range of complex and interdependent design considerations covering network topology formation, number of radios per node, ratio between WiMAX and WiFi radio/node, number of hops at WiFi multi-hop tier and so on. This paper attempts to provide some insights on how different possible hybrid topology designs perform in terms of required node (WiFi access point/ WiMA Xbase station) density. In particular, we investigate how various designs scale towards two loading conditions namely the data rate per user and user density. Tunjukkan kurang

This paper investigates application of a two-tier wireless network system with integrating wireless access and wireless backhaul as the evolution path of providing rural areas with Internet services. The first tier of the proposed network system is the wireless access network which provides interface to user accessing to Internet and enjoy services such as voice over IP, web browsing, and social network. The second tier is the backhaul network in which comprises of a number of wireless routers… Tunjukkan lagi

This paper investigates application of a two-tier wireless network system with integrating wireless access and wireless backhaul as the evolution path of providing rural areas with Internet services. The first tier of the proposed network system is the wireless access network which provides interface to user accessing to Internet and enjoy services such as voice over IP, web browsing, and social network. The second tier is the backhaul network in which comprises of a number of wireless routers that carry traffic from various access networks to a gateway. Tunjukkan kurang

Next generation of wireless broadband network such as WiMAX MMR networks and LTE Advanced support high quality multimedia services with high data transmission rate. Most of the current broadband operates at high frequency and thus has limited transmission range. Multi-hop relaying technology is seen as an efficient solution that could enhance coverage and improves system capacity. However, overall system performances worsen as the number of hop increases. Providing efficient route selection is… Tunjukkan lagi

Next generation of wireless broadband network such as WiMAX MMR networks and LTE Advanced support high quality multimedia services with high data transmission rate. Most of the current broadband operates at high frequency and thus has limited transmission range. Multi-hop relaying technology is seen as an efficient solution that could enhance coverage and improves system capacity. However, overall system performances worsen as the number of hop increases. Providing efficient route selection is one of the key issues to be tackled to improve overall system performance in multi-hop relay network. In this paper, we propose route selection algorithm based on channel condition for WiMAX Mobile multi-hop relay network. We conducted simulation study to evaluate the performance of the proposed scheme. Tunjukkan kurang

Vehicular networks are highly mobile wireless networks that can provide wide variety of services and applications such as public safety communications, crash avoidance, multimedia and Internet access in highways. Designing routing algorithm in vehicular network is a challenging task due to rapidly changing topology and high speed mobility of vehicles. One of the critical issues of vehicular network is frequent path disruptions caused by high speed mobility that leads to broken links which… Tunjukkan lagi

Vehicular networks are highly mobile wireless networks that can provide wide variety of services and applications such as public safety communications, crash avoidance, multimedia and Internet access in highways. Designing routing algorithm in vehicular network is a challenging task due to rapidly changing topology and high speed mobility of vehicles. One of the critical issues of vehicular network is frequent path disruptions caused by high speed mobility that leads to broken links which results in low throughput. This poses complex challenge in ensuring quality of service (QoS). A lot of research around the world is being conducted to define the standards for vehicular communication. In this paper, we study the effect of different duration of transmitting packet and compare different packet size on sending and received packet rate in IEEE 802.16j MMR networks using NCTUns. Meanwhile, cross-layer routing approach is proposed to overcome the challenge. The routing approach is expected to significantly improve QoS in vehicular networks. Tunjukkan kurang

Cooperative relay has been an interesting research area for the past years as it promotes higher data rates and robust to wireless environment. IEEE Work Group initiated the use of relay stations in the IEEE 802.16e standard and it is called IEEE 802.16j. This paper proposed a multi-hop cooperative relay system with space-time codes (STC), with the integration of relay selection. In changing environment, data transmission signals through wireless channels can be degraded by factors like… Tunjukkan lagi

Cooperative relay has been an interesting research area for the past years as it promotes higher data rates and robust to wireless environment. IEEE Work Group initiated the use of relay stations in the IEEE 802.16e standard and it is called IEEE 802.16j. This paper proposed a multi-hop cooperative relay system with space-time codes (STC), with the integration of relay selection. In changing environment, data transmission signals through wireless channels can be degraded by factors like shadowing, fading etc. Cooperative relay system is believed to offer robustness by multipath routes to destination. The cooperative relay system in this work adopted the virtual MIMO (multiple input multiple output) concept. Analysis of performances are made between topologies of space-time cooperative relay systems and compared with cooperative relay transmission. Tunjukkan kurang

Representation of indoor 3D location tracking had been an advantage to globally supported to track the mobile unit everywhere, even in different level of building. Our main focus is presenting development of indoor 3D location tracking to replace the existing 2D location tracking. The 2D location tracking mechanism only supports tracking the mobile unit position in the same level and provides handover or device switching. If the users need to go to another level, user will have to disconnect… Tunjukkan lagi

Representation of indoor 3D location tracking had been an advantage to globally supported to track the mobile unit everywhere, even in different level of building. Our main focus is presenting development of indoor 3D location tracking to replace the existing 2D location tracking. The 2D location tracking mechanism only supports tracking the mobile unit position in the same level and provides handover or device switching. If the users need to go to another level, user will have to disconnect the connection. The development of the system that has a location tracking mechanism responsible to track the position of the mobile unit (such as laptop and PDA). In this paper, the system running in IPv4 framework and set up as a read test bed. The proposed location tracking will be based on Received Signal Strength Indicator (RSSI). The 3D location tracking system will be purely software based with minimum hardware dependent. Tunjukkan kurang

IEEE 802.16m Multihop relay network is assiduously developing to accomplish high capacity services with large cell coverage. However due to lack of physical boundaries and injection of distributed relays, it is known to be more vulnerable to security holes as a trade off. In this paper we propose a new distributed authentication key scheme for Multihop Relays IEEE 802.16m network service. The propose scheme uses decode and forward relays with localized authentication. The scheme works in… Tunjukkan lagi

IEEE 802.16m Multihop relay network is assiduously developing to accomplish high capacity services with large cell coverage. However due to lack of physical boundaries and injection of distributed relays, it is known to be more vulnerable to security holes as a trade off. In this paper we propose a new distributed authentication key scheme for Multihop Relays IEEE 802.16m network service. The propose scheme uses decode and forward relays with localized authentication. The scheme works in distributed authentication to authenticate Subscriber station (SS) and Relay stations (RS) at initial network entry. Our new improved distributed scheme utilizes healthy security issues and the Multihop Relay network application features. Both analysis and performance evaluation shows that our scheme can significantly increases the network throughput and reduce the security holes as well as communication overheads.
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Ubiquitous computing for context aware system collects information from many static and moving devices as well as sensor integrated objects. To provide valuable services, it is necessary to track the location of the users or objects. There are many possible applications that can apply location-assisted service such as child tracking, supermarket trolley alert system, firefighter tracking and many more. This paper proposed an indoor location assisted device switching for Voice over Internet… Tunjukkan lagi

Ubiquitous computing for context aware system collects information from many static and moving devices as well as sensor integrated objects. To provide valuable services, it is necessary to track the location of the users or objects. There are many possible applications that can apply location-assisted service such as child tracking, supermarket trolley alert system, firefighter tracking and many more. This paper proposed an indoor location assisted device switching for Voice over Internet Protocol (VoIP) application using session initiated protocol (SIP) for Wireless Local Area Network (WLAN) based. We present real test-bed measurements for indoor environment giving the results of the system operation as well as the system performance. The system performance shows excellent accuracy of 1m. Tunjukkan kurang

IEEE 802.16j Multihop Relay (MR) is an optional deployment introduced to enhance the coverage and performance of WiMAX network without the need for deploying costly Base Stations (BSs). Multihop Relay network comprises of Multihop Relay BS (MRBS) and Relay Stations (RSs). This paper proposes mesh topology for IEEE 802.16j using adaptive RS group scheduling. The proposed scheduling algorithm introduces new signalling to support functions such as soft and hard horizontal-RS neighbour scanning… Tunjukkan lagi

IEEE 802.16j Multihop Relay (MR) is an optional deployment introduced to enhance the coverage and performance of WiMAX network without the need for deploying costly Base Stations (BSs). Multihop Relay network comprises of Multihop Relay BS (MRBS) and Relay Stations (RSs). This paper proposes mesh topology for IEEE 802.16j using adaptive RS group scheduling. The proposed scheduling algorithm introduces new signalling to support functions such as soft and hard horizontal-RS neighbour scanning, bandwidth request, forwarding of PDUs and connection management. The proposed model is evaluated using NS-2 network simulation. The simulation result shows that the proposed scheduling achieves higher throughput performance compared to IEEE 802.16j tree-topology. Tunjukkan kurang

Wireless sensor networks are expected to be deployed widely in various areas in coming years. The sensor device is small and has low computation power and memory thus perceived as not suitable to be loaded with the high resource IP capabilities. Due to this, the wireless sensor network remains isolated from the Internet. The emergence of IPv6 over low power wireless personal area network (6LoWPAN) has proved that IP communication is borderless and can be used for any devices. It provides a… Tunjukkan lagi

Wireless sensor networks are expected to be deployed widely in various areas in coming years. The sensor device is small and has low computation power and memory thus perceived as not suitable to be loaded with the high resource IP capabilities. Due to this, the wireless sensor network remains isolated from the Internet. The emergence of IPv6 over low power wireless personal area network (6LoWPAN) has proved that IP communication is borderless and can be used for any devices. It provides a simple alternative to other wireless sensor networks and interoperable with IP-legacy systems and tools. However, the use of short addresses within the 6LoWPAN network is not visible to the outside world and hence a proper gateway is required. In this paper, we provide the architecture of the 6LoWPAN gateway which connects the wireless sensor world to the Internet. Our contribution is to provide direct accessibility to wireless sensor network using short address to full IPv6 address translation at the gateway. Our main focus is the flow of packets to and from the gateway including a simple address translation mechanism. The implementation and the use cases of the gateway are also highlighted. Tunjukkan kurang

Fixed-mobile convergence (FMC) is the term used to describe a wide range of mobile services that converge elements of fixed communications infrastructure to complement the core mobile service. IP multimedia subsystem (IMS) is the approach towards merging the fixed and mobile worlds together with the Internet. It enables the efficient provision of an open set of highly integrated multimedia services, combining Web browsing, instant messaging, presence, VoIP and multimedia content delivery etc… Tunjukkan lagi

Fixed-mobile convergence (FMC) is the term used to describe a wide range of mobile services that converge elements of fixed communications infrastructure to complement the core mobile service. IP multimedia subsystem (IMS) is the approach towards merging the fixed and mobile worlds together with the Internet. It enables the efficient provision of an open set of highly integrated multimedia services, combining Web browsing, instant messaging, presence, VoIP and multimedia content delivery etc. over a heterogeneous access network and technologies. Unfortunately, the adoption, support and interest on IMS are still protracted among various players such as operators, service providers, device manufacturers and developers. We believe these players were generally trapped in a vicious circle and hence felt uncertain on adopting IMS, besides having to accommodate the high setup cost, lack of proven business models and further was overshadowed by the web technologies. As the national research institute in Malaysia, we have taken the challenge to set up the OpenFMCtrade lab in Malaysia as to break the vicious circle and to develop an IMS Center of Excellence (CoE) ecosystem through opening up an IMS testbed for all parties to conduct their application development, R&D experiments and interoperability tests. This paper describes the objectives and benefits of establishing our OpenFMCtrade lab, our approach to break the vicious circle, our proposed IMS ecosystem program, the details on provisioning of lab equipments/components, and network topology. Tunjukkan kurang

IP multimedia subsystem (IMS) defines a unified framework that enables convergence of voice, video, data and mobile network technology over an IP-based infrastructure. It is regarded as the standard service delivery platform for providing multimedia applications in the next generation network (NGN). Despite all the hypes, the adoption, support and interest on IMS are still protracted among operators, service providers, device manufacturers and developers. We believe one of the main reasons for… Tunjukkan lagi

IP multimedia subsystem (IMS) defines a unified framework that enables convergence of voice, video, data and mobile network technology over an IP-based infrastructure. It is regarded as the standard service delivery platform for providing multimedia applications in the next generation network (NGN). Despite all the hypes, the adoption, support and interest on IMS are still protracted among operators, service providers, device manufacturers and developers. We believe one of the main reasons for the delay is that these parties felt uncertain on IMS over the setup cost, and were generally trapped in a vicious circle, where one party depends on another to initiate and commit their support on IMS. As the national research institute in Malaysia, we have taken the challenge to break the vicious circle, and committed to build and provide an IMS Center of Excellence (CoE) as testbed for all parties to conduct their application development, experiments and interoperability tests. This paper describes the objectives and benefits of establishing our IMS testbed, our approach to break the vicious circle, the formation and responsibility of an NGN/IMS workgroup (WG), and the specifications and focus of our IMS testbed. Tunjukkan kurang

Providing end-to-end communication in heterogeneous Internet working environments is a challenge. Handover delay is one of the problematic issues that users are face in the heterogynous networks. However, in the case of both WiMAX and WiFi technologies located at the same base station (BS); the vertical handover (VHO) delay will be less compared with two conventional WiMAX/WiFi heterogonous networks with two different wireless Internet service providers (WISP). However, protocol conversion is… Tunjukkan lagi

Providing end-to-end communication in heterogeneous Internet working environments is a challenge. Handover delay is one of the problematic issues that users are face in the heterogynous networks. However, in the case of both WiMAX and WiFi technologies located at the same base station (BS); the vertical handover (VHO) delay will be less compared with two conventional WiMAX/WiFi heterogonous networks with two different wireless Internet service providers (WISP). However, protocol conversion is still adding delay and jitter for data exchange between the needed two technologies. In this paper, In order to reduce the delay in protocol conversion, a new design for WiWi (WiMAX and WiFi) adaptation layer is proposed. The realization of the interworking between these two standards is discussed and evaluated. Tunjukkan kurang

We introduce computer simulation results that illustrate performance trade-offs associated with the mixed priority queueing model (MPQ) for the initial introductory phase of switching and demultiplexing fabrics for ATM based high-speed multimedia networking services. We study the hierarchical shared memory ATM switch architecture in which the queues for all the switch output ports share space flexibly in a common buffer. Using computer simulation of this shared buffer ATM switch under both… Tunjukkan lagi

We introduce computer simulation results that illustrate performance trade-offs associated with the mixed priority queueing model (MPQ) for the initial introductory phase of switching and demultiplexing fabrics for ATM based high-speed multimedia networking services. We study the hierarchical shared memory ATM switch architecture in which the queues for all the switch output ports share space flexibly in a common buffer. Using computer simulation of this shared buffer ATM switch under both uniform and bursty traffic, we investigate the delay and cell loss probability (CLP) for the each class of traffic. Our finding supports the MPQ model as a worthwhile strategy for buffer management to improve the quality of service (QOS) in an ATM etwork Tunjukkan kurang

The authors propose a method for evaluating the impact of bursty traffic sources on the performance of an ATM multiplexer which can handle packetised voice, data and video traffic. The multiplexer is modelled as a single-server queue with batch phase type Markov renewal input. The authors describe an analytical approach to the solutions of such queueing systems with finite capacity using the matrix analytic method. The methodology was chosen because its ability to model exactly complex… Tunjukkan lagi

The authors propose a method for evaluating the impact of bursty traffic sources on the performance of an ATM multiplexer which can handle packetised voice, data and video traffic. The multiplexer is modelled as a single-server queue with batch phase type Markov renewal input. The authors describe an analytical approach to the solutions of such queueing systems with finite capacity using the matrix analytic method. The methodology was chosen because its ability to model exactly complex nonMarkovian models having correlated, nonrenewal input processes. It is nearly impossible to obtain exact expressions using the classical method of generating functions. A study of different mixed traffic assumptions indicates that bursty traffic does have a very significant effect on the loss performance Tunjukkan kurang

Priority control is one possible solution for achieving traffic control in an asynchronous transfer mode (ATM) network. A priority congestion control scheme known as partial buffer sharing (PBS) is evaluated by using the matrix-analytic approach to obtain its stationary probabilities. An ATM bursty source model description is included, together with that of a phase-type Markov renewal process. A study of two classes of bursty traffic in an ATM multiplexer indicates that the burstiness of the… Tunjukkan lagi

Priority control is one possible solution for achieving traffic control in an asynchronous transfer mode (ATM) network. A priority congestion control scheme known as partial buffer sharing (PBS) is evaluated by using the matrix-analytic approach to obtain its stationary probabilities. An ATM bursty source model description is included, together with that of a phase-type Markov renewal process. A study of two classes of bursty traffic in an ATM multiplexer indicates that the burstiness of the traffic has a significant effect on its performance Tunjukkan kurang