Mazlan Abbas

A gateway solution for IPv6 wireless sensor networks

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.

A survey of cognitive radio and TV white spaces in Malaysia

Cognitive radio CR enables spectrum sharing by allowing new unlicensed services from secondary users to operate in pre-allocated bands in an opportunistic manner. TV white space TVWS is a portion of the spectrum in ultra-high frequency UHF and very-high frequency bands, which is not utilised by primary users in specific time and location. It is envisaged that more spectrum will be available after digital switchover DSO TV transmission replaces the current analogue system. Recently, the regulators in the USA and in the UK have given approval for companies to operate new communication systems with the capability of utilising TVWS spectrum. This paper provides a comprehensive overview of the CR technology and quantifies the TVWS status in Malaysia to expose the spectrum reuse opportunities for future secondary user deployment. Taking the 18 major cities in Malaysia into consideration, we find that all seven TV stations utilise from two to seven of the UHF channels. In our analysis, three usage scenarios were considered, where the utilisation of the 40 UHF channels is full, half and a third. For each case, it was discovered that TVWS was 82.5%, 65% and 46.1%, which can be opportunistically utilised by CR users. Copyright

WiFi/WiMAX Heterogeneous Seamless Handover

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.

An Indoor 3D Location Tracking System Using RSSI

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.

Performance evaluation of Binary Spray and Wait OppNet protocol in the context of emergency scenario

Opportunistic Networks (OppNets) can be used as an alternative way to communicate or to interact with each other when a fixed communication infrastructure is down during an incident like an earthquake or tsunami. In this paper, we investigate the factors effecting the performance of an OppNets routing protocol which is Binary Spray and Wait protocol in a condition of emergency situation. We have conducted four experiments; 1) 20 pedestrians, 2) 20 cars, 3) 100 pedestrians, and 4) 100 cars. We evaluated this protocol using Opportunistic Networking Environment (ONE) simulator and analyze the performance in term of delivery probability, number of message dropped, latency average, and hop count average by varying size of buffer and message size.

External tube drainage or omentoplasty in the management of residual hepatic hydatid cyst cavity: a prospective randomized controlled study.

Background: Surgical procedures advocated for management of residual hepatic hydatid cyst cavity have been a subject of controversy. The aim of this study was to compare omentoplasty (OP) and external tube drainage (ETD). Material and methods: This was a prospective randomized controlled study conducted on radiologically documented cases of hepatic hydatidosis (n=50) in a tertiary care hospital of Kashmir. Patients were divided into two groups; in one group ETD was performed and in another OP was done. Results: Twenty-eight patients were offered ETD and 22 OP. There was no statistically significant difference in mean operative time. The overall complication rate was higher in ETD (42.86%) as compared to OP (22.73%). In ETD group two patients had bile leak and infection of residual cavity each; whereas no such complication was seen in OP. The mean pain scores were elevated in ETD (p<0.0016).The mean hospital stay was more in ETD as compared to OP (p<0.0031). Also time for resumption of activities of daily life was more in ETD (p<0.0026). The recurrence of disease was seen in three patients in ETD as compared to none in OP. Conclusion: Omentoplasty offers a number of advantages over external tube drainage and should remain the preferred option whenever possible.

Adaptive RS-group scheduling for WiMAX multihop relay

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.

An investigation of vegetation effect on the performance of IEEE 802.11n technology at 5.18 GHz

In this paper, the performance of IEEE 802.11n Wi-Fi technology at 5.18 GHz frequency in one of the rural areas in Malaysia, which is typically covered by dense tropical foliage, is evaluated and analyzed. To our best knowledge, studies on the performance of the IEEE 802.11n technology in foliage area have not been fully explored. We have conducted line-of-sight and non-line-of-sight measurements through the tropical foliage using directional high gain antennas to determine the throughput and other well-known performance metrics. It is observed that by utilizing the key features of 802.11n such as channel bonding and short guard interval, superior performance results can be achieved for both aforementioned situations. Precise correlation of utilized hardware specification and acquired results in different points is another aspect of this work. The findings are useful for future rural wireless deployment particularly with low height antenna using IEEE 802.11n technology. (6 pages)

WiFi/WiMAX seamless convergence with adaptive vertical handover for continuity of Internet access

The next generation of the wireless networks will consist of several overlapping tiers. Provision of undisrupted communication to mobile users is a challenging task. Handover delay is one of the problematic issues that users are faced in the heterogeneous networks. However, in the case of both the WiMAX and the WiFi technologies which are located at the same base station (BS), the vertical handover (VHO) delay will be less as compared with the two conventional WiMAX/WiFi heterogeneous networks with two different wireless Internet service providers (WISP). Nevertheless, 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 the protocol conversion, a new industrial design for WiWi (WiMAX and WiFi) adaptation layer is proposed. The realization of the interworking between these two standards is discussed and evaluated. The results show that the proposed scheme-with the scenario under study- has better performance than other related works.

Cross-layer routing approach in highly dynamic networks

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.