Yim Fun Hu

Mobility management incorporating fuzzy logic for heterogeneous a IP environment

The next generation in mobility management will enable different mobile networks to interoperate with each other to ensure terminal and personal mobility and global portability of network services. However, in order to ensure global mobility, the deployment and integration of both satellite and terrestrial components are necessary. This article is focused on issues related to mobility management in a future mobile communications system, in a scenario where a multisegment access network is integrated into an IP core network by exploiting the principles of Mobile IP. In particular, attention is given to the requirements for location, address, and handover management. In a heterogeneous environment, the need to perform handover between access networks imposes particular constraints on the type of information available to the terminal and network. In this case, consideration will need to be given to parameters other than radio characteristics, such as achievable quality of service and user preference. This article proposes a new approach to handover management by applying the fuzzy logic concept to a heterogeneous environment. The article concludes with a presentation of mobility management signaling protocols.

A survey of architectures and scenarios in satellite‐based wireless sensor networks: system design aspects

This paper is not a survey related to generic wireless sensor networks (WSNs), which have been largely treated in a number of survey papers addressing more focused issues; rather, it specifically addresses architectural aspects related to WSNs in some way connected with a satellite link, a topic that presents challenging interworking aspects. The main objective is to provide an overview of the potential role of a satellite segment in future WSNs. In this perspective, requirements of the most meaningful WSN applications have been drawn and matched to characteristics of various satellite/space systems in order to identify suitable integrated configurations. Copyright

Implementation of fuzzy multiple objective decision making algorithm in a heterogeneous mobile environment

Mobile satellite networks are now being utilized to provide complementary service coverage to their terrestrial counterparts. The migration from voice-dominated service delivery to a data-centric environment implies that the choice of one particular access network over another will need to take into account many different criteria, which previously need not have been considered. For this reason, it is important that a suitable decision making algorithm is designed to ensure that all of the different characteristics of the system are taken into account when making the segment selection for a particular service delivery. In this paper, a segment selection algorithm based on the fuzzy multiple objective decision making algorithm is presented. This algorithm is analyzed to show how the overall performance of a multi-access segment network can be improved by varying the relative importance of certain service and network characteristics.

Biomolecule immobilization techniques for bioactive paper fabrication

AbstractResearch into paper-based sensors or functional materials that can perform analytical functions with active recognition capabilities is rapidly expanding, and significant research effort has been made into the design and fabrication of bioactive paper at the biosensor level to detect potential health hazards. A key step in the fabrication of bioactive paper is the design of the experimental and operational procedures for the immobilization of biomolecules such as antibodies, enzymes, phages, cells, proteins, synthetic polymers and DNA aptamers on a suitably prepared paper membrane. The immobilization methods are concisely categorized into physical absorption, bioactive ink entrapment, bioaffinity attachment and covalent chemical bonding immobilization. Each method has individual immobilization characteristics. Although every biomolecule–paper combination has to be optimized before use, the bioactive ink entrapment method is the most commonly used approach owing to its general applicability and biocompatibility. Currently, there are four common applications of bioactive paper: (1) paper-based bioassay or paper-based analytical devices for sample conditioning; (2) counterfeiting and countertempering in the packaging and construction industries; (3) pathogen detection for food and water quality monitoring; and (4) deactivation of pathogenic bacteria using antimicrobial paper. This article reviews and compares the different biomolecule immobilization techniques and discusses current trends. Current, emerging and future applications of bioactive paper are also discussed.n Online Abstract FigureTrend Paper: Biomolecule immobilization techniques for bioactive paper fabrication

Demographically weighted traffic flow models for adaptive routing in packet-switched non-geostationary satellite meshed networks

In this paper, a performance analysis of adaptive routing is presented for packet-switched inter-satellite link (ISL) networks, based on shortest path routing and two alternate link routing forwarding policies. The selected routing algorithm and link-cost function are evaluated for a low earth orbit satellite system, using a demographically weighted traffic flow model. Two distinct traffic flow patterns are modelled: hot spot and regional. Performance analysis, in terms of quality of service and quantity of service, is derived using specifically developed simulation software to model the ISL network, taking into account topology adaptive routing only, or topology and traffic adaptive routing.

A Low Power Wireless Sensor Network for Gully Pot Monitoring in Urban Catchments

Sewer and gully blockages are the main cause of residential sewer flooding in the U.K. A low-cost and power efficient wireless sensor mesh networking communication system has been designed, developed and implemented to provide adequate warning on potential blockage incidents to prevent sewer failure. By monitoring the water level of the gully pot at each residential property, the water company will be proactively informed of the best course of actions to eliminate the causal problem, i.e., blockage and leakage within the sewer infrastructure. Hence, the number of residential sewer flooding and pollution incidents can be reduced. The prototype system consists of eight Zigbee based wireless sensor nodes and a GPRS enabled data gatherer. Each Zigbee sensor node comprises of a radio transceiver, a data acquisition board and an acoustic sensor probe. Field trials were carried out in an outdoor scenario to cross-validate the theoretical and practical performance of the prototype system. The results in terms of durability of sensors, sensor nodes and gateways and reliability of communication under real operational conditions and within a typical inner city urban environment are discussed. The problems encountered and solutions to tackle these problems were addressed.

Performance of intersegment handover protocols in an integrated space/terrestrial-UMTS environment

The universal mobile telecommunications system (UMTS) will deliver a convergent network incorporating cellular, cordless, wireless local loop, and satellite technologies. A signaling protocol for intersegment handover (ISHO) in an integrated space/terrestrial-UMTS environment is presented. After discussing a number of possible ISHO scenarios, backward mobile-assisted handover (HO) incorporating signaling diversity is chosen as the most appropriate ISHO scheme. Based on the generic radio-access network (GRAN) concept and by using a satellite-UMTS network architecture and functional model, the derivation of an ISHO protocol is presented. The performance of this protocol is analyzed and evaluated in terms of the service interruption time, execution signaling time, and the end-to-end signaling time. Simulation results show that, in agreement with the GRAN concept, the service interruption time is independent of the signaling protocol and depends only on the satellite round-trip delay and the radio interface characteristics. The interarrival rate of the ISHO requests affect the performance of the protocol only when the value of the mean service time is increased. However, even in such a situation, the performance of the protocol is still considered acceptable.

Broadband Satellite Multimedia

The broadband satellite multimedia (BSM) architecture standardised by ETSI defines a satellite independent service access point (SI-SAP) interface layer that separates the satellite independent features of the upper layers from the satellite dependant features of the lower layers, and provides a mechanism to carry IP-based protocols over these satellite dependent lower layers. This enables interoperability at the IP layer between satellite systems of different physical and link layers technologies that fully comply with the SI-SAP concept. This study reviews past and current standardisation activities including the BSM quality of service (QoS) architecture, security architecture, network management that have been carried out by the ETSI Technical Committee-Satellite Earth Stations and Systems (TC-SES)/BSM working group and looking into the future to extend current SI-SAP functions that can enhance existing QoS provision and security management capabilities as well as proposing a mobility management architecture that complies with the IEEE 802.21 media independent handover framework to support BSM mobility and to allow integration of satellite networks with fixed and mobile network infrastructures. A service-based network management architecture is also proposed to allow management flexibility and integration of business and operation support functions, paving the way for satellite integration into the Internet of the future.

Satellite-UMTS traffic dimensioning and resource management technique analysis

The universal mobile telecommunications system (UMTS) will consist of space UMTS (S-UMTS) and terrestrial UMTS (T-UMTS) components. An algorithm for predicting the traffic capacity in terms of the number of subscribers for the satellite component of UMTS is presented. The algorithm takes into account the takeup characteristics of new products, the growth of gross domestic product (GDP), the projection of population, the tariff of the service, and price fall over the forecast period. The predicted traffic is used to generate a traffic grid in terms of Erlang of dimension 36/spl times/72 in steps of 5/spl deg/ in both the latitude and longitude directions. The traffic grid is used to evaluate the performance of a dynamic channel allocation (DCA) technique as, well as a fixed channel allocation (FCA) technique. Both channel allocation techniques have been considered with the queuing of handover (QH) requests. In order to compare the respective techniques performance, a low-earth orbit mobile satellite system (LEO-MSS) mobility model is developed to take into account the effect of satellites motion during interbeam handovers. A theoretical model for obtaining the values of blocking probabilities for low-traffic loads is presented. Finally, the performance of the DCA-QH technique is compared with the FCA-QH technique under suitably defined traffic and mobility conditions.

Wireless sensor transmission range measurement within the ground level

The maximum transmission range of crossbow wireless sensors are considered and discussed for sensor to sensor on ground level communication, and sensor on ground level to base station on lamppost. Two different crossbow wireless sensors kits operated at 900 MHz and 2400 MHz bands were used. Both indoor and outdoor sensor to sensor communication ranges were performed for one and five different types of environments respectively. The performance of the crossbow mote with four different types of antennas, in term of transmission range was considered. Several measurement results for fixed power transmission of the two operated frequencies were recorded for comparisons.