R.M. Edwards

Performance evaluation of routing protocols in vehicular ad-hoc networks

This paper presents a reactive location routing algorithm that uses cluster-based flooding for Vehicular Ad-hoc Networks (VANET). We compare both position-based and non-position-based routing strategies in typical urban and motorway traffic scenarios. A microscopic traffic model, developed in OPNET, is used to evaluate the performance of the Location Routing Algorithm with Cluster-Based Flooding (LORA_CBF), Ad-Hoc On-demand Distance Vector (AODV) and Dynamic Source Routing (DSR) in terms of average Route Discovery (RD) time, End-to-End Delay (EED), Routing Load, Routing Overhead, Overhead, and Delivery Ratio.

Bandwidth and Impedance-Matching Enhancement of Fractal Monopole Antennas Using Compact Grounded Coplanar Waveguide

Grounded coplanar waveguides (GCPW) are used to enhance antenna characteristics, namely, reference to the VSWR <; 2 bandwidth and the input impedance dynamic range. A printed fractal monopole such as the Sierpinski-Carpet (SC) antenna can be considered as a good candidate for comparing a coaxial-fed system with a GCPW-fed antenna. Conventional SC can be applied at 6.25-8.4 GHz (ref to VSWR <; 2 ), while modified SC matches throughout the 4.65-10.5 GHz (ref to VSWR <; 2 ). Clearly, this new feeding technique changes the behavior of the fractal elements from multiband to wideband. The GCPW-fed antennas have a low crosspolar field and a well-behaved pattern over the enhanced ones. This system of antennas is a possible competitor for the FCC ultrawideband radio short, fat pipe systems. In addition, time-domain analyses are performed to realize the proposed antenna time-domain application over ultrawideband.

Experimental Verification of a Modified Specific Anthropomorphic Mannequin (SAM) Head used for SAR Measurements

This paper investigates a method of facilitating specific absorption rate (SAR) measurements in the head when using a 1800 MHz radiation source placed in front of the face. A specific anthropomorphic mannequin (SAM) head phantom is modified by removing the rear most part to enable fully-automated scanning of the face region by a DASY4 electric-field probe. Prior to the modification, simulations were carried out in FDTD to establish the optimum area to be removed. This paper compares predicted local SAR values behind the face with actual measurements carried out using the new modified SAM phantom head. Measurements show good agreement with simulations, indicating that the modified SAM head is suitable for SAR measurements when the source is placed in front of the face.

On the effects of straight metallic jewellery on the specific absorption rates resulting from face-illuminating radio communication devices at popular cellular frequencies.

This paper presents simulated and measured phantom results for the possible effects that head worn jewellery may have on the relative levels of energy absorbed in the human head with cellular enabled mobile communication devices. The FDTD electromagnetic code used with simple and complex anatomical mathematical phantoms was used to consider the interactions of metallic jewellery, heads and representative sources at 900 and 1800 MHz. Illuminated metallic pins of different lengths were positioned in front of the face. Initially, a homogenous phantom was used to understand the relative enhancement mechanisms. This geometry allowed the results to be validated with the industry standard DASY4 robot SAR measurement system related to the CENELEC head. Jewellery pins were then added to an anatomically realistic head. The relative increase in the 1 g and 10 g SAR, due to a pin with a length 0.4lambda near the eyebrows of a complex, anatomically realistic head was approximately three times at 1800 MHz. Such pins increased the SAR averaged over a 1 g or 10 g mass by redistributing the energy absorbed inside the head and focusing this energy towards the area of the head nearest to the centre of the pin. Although, the pins increased the SAR, the SAR standards were not breached and the jewellery produced lower values than those of previous studies when the source was positioned close to the ear.

Policy for enhancement of traffic in TDMA hybrid switched integrated voice/data cellular mobile communications systems

Major types of data for multimedia with mobile communications are voice, WWW, and FTP. Different regimes for quality of service (QoS) exist for each with reference to delay sensitivity. Sharing available radio resource has been inherently based on the characteristics of data types and their associated QoS. In this paper, we present a new policy for integrated services of voice and data that is pertinent to a TDMA system using a hybrid-switching mode. Our method provides significant improvements in traffic capacity for data with virtual transparency to voice users.

Dual Band-Notch CPW-Ground-Fed UWB Antenna by Fractal Binary Tree Slot

In this paper, a compact dual band-notch UWB antenna with CPW-Ground-fed is presented. It is desired to achieve band notch antenna by etching a narrowband dual resonance fractal binary tree in the radiation element of the conventional UWB antenna. This antenna is capable of reducing the interference at the WLAN bands by eliminating the 4.95-6.05 GHz band. The proposed antenna has compact size of 16 × 22mm2 including the ground plane. This miniature size delivers a good radiation patterns with mono-polar characteristics. In this proposed antenna design, the gain is suppressed very well in the desired WLAN bands. The maximum suppression is in 5.61 GHz that is 13.25 dB less than the gain of normal antenna.

Bicep mounted low profile wearable antenna based on a non-uniform EBG ground plane - flexible EBG inverted-l (FEBGIL) antenna

This novel paper presents a low profile antenna based on the properties of a non-uniform electromagnetic bandgap (NU-EBG), i.e. a non-uniform high impedance surface (NU-HIS). The structure, referred to as Flexible EBG Inverted-L (FEBGIL) antenna, is an efficient wearable antenna incorporating a planar inverted-L element adjacent to some non-uniformly spaced high impedance elements. While the bandwidth is approximately 10% at 1.85 GHz, the overall electrical size is quite small providing an ideal condition for the antenna to be worn on biceps (upper arms). This design is able to minimize electromagnetic interaction with the body on which it is worn and therefore can reduce Specific Absorption Rate (SAR) and degradation in radiation efficiency.

A location-based routing algorithm for vehicle to vehicle communication

We present a location-based routing algorithm with cluster-based flooding for vehicle to vehicle communication. We consider a motorway environment with associated high mobility and contrast and compare position-based and non-position-based routing strategies, along with a limiting function for flood mechanisms in reactive ad-hoc protocols. The performance of dynamic source routing (DSR) and ad-hoc on-demand distance vector routing (AODV) for non-positional and location routing algorithm with cluster-based flooding (LORA/spl I.bar/CBF) for positional algorithms are considered. Our proposed flooding limiting technique is compared with AODV and DSR by simulation. The mobility of the vehicles on a motorway using a microscopic traffic model developed in OPNET has been used to evaluate average route discovery (RD) time, end-to-end delay (EED), routing load, routing overhead, overhead, and delivery ratio.

Using the cluster-based location routing (CBLR) algorithm for exchanging information on a motorway

We simulate inter-vehicular data traffic on a motorway using a multi-hop network with a cluster-based ad-hoc regime over 802.11 spread-spectrum wireless. Both the protocol and its application are novel and are germane to demanding access point deployment environments such as motorways, battlefields and disaster zones. Packet voice sustainability is plotted as a function of inter-vehicle velocity for a dual carriage motorway with constrained lanes. Finally a comparison between FHSS and DSSS wireless with the algorithm is presented.

A wearable flexible multi-band antenna based on a square slotted printed monopole

This paper presents a novel flexible wearable multi-band printed monopole antenna on a neoprene substrate. Bands covered are GSM 900 (890-960 MHz), DCS (1710- 1880 MHz), PCS (1850-1990 MHz), UMTS (1920-2170 MHz) and WLAN 2.4 GHz (2400-2484 MHz) bands. The antenna is optimised for performance on the body.