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In dense radio frequency identification (RFID) situations where the coverage of multiple interrogators overlaps, a key challenge is to mitigate interrogator-involved collisions. Among the solutions that have been proposed to reduce or avoid such collisions, Geometric Distribution Reader Anti-collision (GDRA) protocol achieves the highest throughput exploiting Geometric distribution to minimise contention among interrogators. This approach is compatible with current RFID protocols, such as EPC Gen2, ISO18000-6C and ETSI EN 302 208–1 without extra hardware support. In this paper, based on GDRA, we propose an enhanced protocol, called Dynamic GDRA (DGDRA), in which different interrogators dynamically and independently adapt their own Geometric distributions based on the experienced number of successful transmissions and collisions. Simulation results confirm that the proposed DGDRA provides higher throughput and enhances fairness performance compared to the original anti-collision scheme.

In this paper, a method for the study XBee latency is researched. Study of an XBee radio link is important when considering machine control over wireless. Furthermore, knowledge of an XBee latency probability distribution is useful in the simulation of machine control over wireless. In this research, a camera gimble, typical of those used by expert observers with drones was proposed as the machine control activity. The test bed used was created using two XBee IEEE 802.15.4 MaxStream modules in a point to point configuration. In drone mounted machine control over an XBee channel a controller sends command messages to a flying drone. Lower latency in camera control yields shorter reaction times for camera operators and a more comfortable operation experience for untrained expert observers.

In this paper, a new method for augmenting current self-localization methods for autonomous based on Global Navigation Systems (GNSS) and Lidar is introduced as a backup system for primary equipment. The method uses Radio Frequency Identity Tags (RFID) running under a modified EPC Gen2 Standard. Simulated results are presented for a representative 6. 54km circular track around Loughborough, UK town centre with a 911 items inventory of roadside furniture. The virtual test track as input for an RFID tag simulator that uses an interrogator/inventory protocol. The technique is shown to be a good candidate for improving safety in Autonomous Vehicles and position finding for vehicles in general.

This paper presents the results of a wideband channel measurement campaign carried out in an indoor environment with representative inventory of a factory. The measurements were carried out using a frequency domain channel sounder from 3.4 - 3.8 GHz and the virtual array method was adopted for averaging small-scale fading effects. From the average power delay profile (APDP), parameters for the Saleh-Valenzuela (S-V) model were extracted for line-of-sight (LoS) and non line-of-sight (NLoS) sites. The ray decay from the S-V model increased with cluster delay for all LoS sites and the delay spread for NLoS sites were higher than LoS locations. The NLoS delay spread was also higher than the results obtained at 2.4 GHz for the same measurement locations. The APDPs from both LoS and NLoS sites showed clustering effects with a mean cluster number of 8/7 for LoS/NLoS sites.

In this paper, three experiments with coupled dipoles were carried out in order to determine the optimal distance where an efficient communication link can be established. The simulations results showed that when the subcutaneous dipole is installed adjacently to the surface of the skin, the dipole mounted above the skin level should be in the range of 20 mm to 25 mm for efficient communication. Subsequently, the influence of the dielectric parameters of the human tissue on wave propagation has also been presented in this work.

This paper presents the effect of water on a pair of 1.8GHz on-body diversity monopole antennas mounted on the forearm of a sitting male static volunteer. Application of a water layer to the forearm was seen to both reduce efficiency and increase directivity leading to a slight overall increase in gain. Increased gain was shown to increase antenna correlation thereby reducing diversity gain in the antenna pair.

Spectacular expansion of RFID systems and applications by several industries such as business, electronics, health, marketing, transportation, etc. has made RFID ever more popular. Within this context, the industry search for lower tag weight and low cost system together with solemn security to satisfy the consumer. Tag search is among the most requested protocols in such systems. Being light weight is regarded as another important specification for the said protocols, so that they can be utilized in low expense tags. In this paper, a server-less search protocol is proposed in low expense tags with the aid of NLFSRs and simple logical operations to conflict with security attacks. This protocol requires only a two steps information exchanges between tag and reader, and although it has simple structure, but is completely safe against most of the known security attacks. In comparison with other protocols, this protocol also requires a small number of gates for implementations. There are no need to exclude the collisions in tags as its other privileges.

This paper evaluates the suitability of existing 2-D interpolation techniques to estimate RF power density levels within an automobile manufacturing plant in the UK. This analysis is based on a measurement campaign carried out at five locations within the plant. Using widely accepted interpolation techniques, a power density grid that provides an estimate of power density distribution for the plant can be created. The interpolation techniques evaluated are: Inverse distance weighting, Kriging and Spline. The analytical results showed that the Kriging technique was more suitable for estimating power density across the entire band (0.2 GHz – 3 GHz). Using the power density grid obtained, an energy profile for a pallet traveling in a predefined production loop was estimated. As a result, it becomes essential to carefully select the estimation technique to adopt, particularly when the measurement dispersion points are sparse.

This paper presents the use of two generic on-body antenna types, a probe and a magnetic dipole with and without a radome constructed of Rohacell. Its is shown that Rohacell minimally attenuates the electromagnetic signal transmitted or received by the antenna concluding to the cover being essentially transparent to radio waves at 2.4GHz and 5.8GHz. In on-body meaurements radomes can be used to protect the antenna surfaces from damage and protect nearby personnel from being accidentally struck by quickly rotating antennas. Performance of two on-body antennas is considered on and off the body by measurement and simulation. Results show that the Rohacell protection has negligible effect on the performance of the antenna systems regardless of loading by humans and polarity. This paper aims to enlighten use of Rohacell to protect antennas used for body centric experiments and experiments in body-centric settings.

Typically mobile handsets are used in close proximity to the users head, hand and shoulder. The radio frequency energy received and produced by the handset interacts with biological tissue causing severe perturbations to the radio channel. Human tissue is both dispersive and lossy therefore both the frequency and amplitude of any wave interacting with a user either in the uplink or the downlink will be changed. Identification of the presence of humans can be achieved by comparisons between the channel impulse response with and without a human user. This paper presents measurements and analytical framework for the determination of human presence in a cellular communication system over the air channel comprising a human, a handset and base station. For this analysis the chosen bearer is GSM.

This paper presents RF power density measurements carried out at an automobile manufacturing plant in the UK. This measurement campaign was carried out in order to quantify the amount of ambient RF power available within the plant. Due to the location of the plant, low power density measurements were recorded in the base-station downlink. The dominant frequencies at the plant were GSM-1800 and 3G. Average input RF power density for horizontal and vertical polarizations showed few variations in amplitude compared to the maximum hold technique for the frequency band surveyed. The measurement campaign showed that at some locations at the plant, the input RF power density for 3G mobile transmit band was more than the base-station downlink.

A new low profile antenna comprised of a PIFA and an Artificial Magnetic Conductor (AMC) are presented. The PIFA antenna is placed at the edge of the AMC structure for bandwidth improvement. Use of a square-ring elementary element AMC without via is shown to maintain the PIFAs radiation efficiency with a low profile. The chosen AMC exhibits the required zero phase reflection coefficient for normally incident waves. Results suggest that additional directivity can be achieved for the combined PIFA/AMC system.

Use of the body as a platform for wearable electronics is a topical subject. Omnidirectional antennas are thought to be useful for antennas in body area networks. However, the desirable properties of omnidirectional radiation patterns close to humans are severely diminished due to the lossy load nature of biological matter and high levels of scattering due to mismatch. To alleviate these problems two or more antennas can be used on the body. In this paper, two on body antennas are used with selective combining and then compared with their free space equivalents. The frequency of operation is 2.4GHz.

While designing a wearable antenna for on-body communications, particular importance is given to lessen the lossy effects of the human body on transmission coefficient. This paper presents experimental and simulation results for two different polarizations of center-fed dipole antenna on human body at mobile communication frequency. The isolated parameter is S 21 (dB). Early results suggest that vertical polarization of dipole gives better transmission coefficient than horizontal polarization.

This paper considers a twin arm wire spherical helical antenna with a balanced feed. Each arm of the antenna forms a hemispherical helical antenna. The frequency of operation is 2.45 GHz. Under a genetic algorithm the antenna was optimised for axial ratio, gain and half-power beam width using core permittivity, radius, wire thickness and length. In the limit the antenna becomes two flattened spiral arms with a balanced feed. The GA design included the possibility of core material of higher permittivity than free space that could be placed either inside the windings, inside and extended beyond the windings or only outside the windings as a shell. The GA selected structures exhibit broad beam patterns with good gain and useful axial ratio when simulated using the time-domain Transmission-Line Matrix (TLM) method (CST Microwave Studio). Results are presented and compared for optimised versions of the ellipsoidal helical and dual planar spiral antenna with balanced feeds for use on the 2.45 GHz ISM band.

A compact ultra-wideband antenna is used to demonstrate a notching method using a fractal for the amelioration of interference from legacy users such WiMAX and WLAN. The achieved results show that this antenna operates in the range of frequencies specified by FCC for BAN and relatively stable characteristics in the presence of simulated biological tissue representing a forearm. The antenna is fed with a compact waveguide and has useful properties with a main beam parallel to and perpendicular to the skin. The antennas have footprints of 1.6cm ×2.2cm and 2cm × 2.6 cm including co-planar feed.

This study investigates the Over the Air (OTA) power measurements from a mobile phone when held by the CTIA hand phantom compared to a number of participant's hands. A measurement setup in a shielded environment was setup to ensure that all the participants held the mobile phone in a similar fashion to the hand phantom so that accurate comparisons could be made. Measured results show that the received power from all the participants was lower than that received from the hand phantom when the index finger covered the whole antenna region.

In this paper, a compact band-notch UWB antenna with CPW-fed is presented. A band notch antenna is designed by etching a band resonance hexagonal shape in the radiation element of the conventional UWB antenna. This antenna is capable of reducing the interference at the WLAN bands by eliminating the 5–5.7 GHz band. The proposed antenna has compact size of 16 × 26 mm2. This miniature size provides a good radiation patterns with mono-polar characteristics. In this designed antenna, the gain is suppressed very well in the desired WLAN bands.

This paper considers the design and build of a balanced thin wire ball and antenna suitable for on-body applications when worn as an accessory such as a free hanging toggle or pompom. A novel structure that consists of a dipole, fed with shielded wire with the linear sections extended by two spiral arms of thin wire wound onto a ball of low dielectric material. The target frequency is 2.45 GHz. Good bandwidth, good gain and axial ratio are achieved via simulation. Results using a multi-grid formulation of the time-domain Transmission-Line Matrix (TLM) method (CST) validated using NEC are presented.

In this paper the fractal method is used to realize two novel antennas useful for Ultra Wideband Radio. Fractals have self-similarity, which lends them to simple replication and desirable space filling for current path maximisation in a given footprint. Candidate fractal antennas considered here are a modified Minkowski fractal and a Koch-Square loop fractal. Both antennas are optimized to operate within the FCC UWB mask with a −10 dB of reflection loss. Reasonable gain and broadside directivity are also achieved. The antennas were synthesised with the Method of Moments package 4NEC2X.

In the design and synthesis of wearable antennas isolation distance from the body is a critical parameter. This paper deals with the comparison of perturbations caused to the matching of simple linear and circular polarized patch antennas due to the close proximity of a human torso and rectangular box phantom filled with muscle simulating liquid at 1.8GHz. The isolated variable is return loss (S 11 ). Results show that both linear and circularly polarized antennas produce an optimal return loss closer to the surface of a typical phantom than the back of a human volunteer.

As of September 2010 trends suggested that disruptive technologies were likely to include wireless communications devices integrated into clothing. A new set of antennas is required for Body-centric applications. Such antennas will form a key component in Body area networks (BANs) in which transmitters and receivers are co-located on the body, implanted under the skin, directly attached to the skin or integrated into clothing. Notable drivers are multimedia, medical and military applications. These drivers combined with the geo-sensitive facilitators of global positioning system (GPS), Galileo global navigation satellite system (GNSS), cellular, unlicensed 802.11x and short range technologies such as Bluetooth and UWB have made Body-centric antennas fundamental in achieving the desired low power signal budgets required.

It has been demonstrated [2, 6] that a Pareto ranked genetic algorithm can be usefully applied to a printed wire Archimedean single arm spiral to obtain optimal results. Results presented at conference will optimize the novel ball spiral antenna using a GA with seven gene chromosomes and possible objectives of impedance −6dB bandwidth, good circular polarization over both hemispheres in close proximity to the human body and stable gain.

This paper presents a flexible Frequency Selective Surfaces (FSS)/High Impedance Surface (HIS) structure for wearable communication systems. When designed using flexible electro-textiles for radiating elements and fabric dielectric substrates periodic electromagnetic structures may offer performance advantages in wearable antenna design. The traditional printed circuit etching technique has been used on electro-textiles to design HIS structure showing electromagnetic bandgap (EBG) behaviour. The existence of an EBG is experimentally verified from 10 to 12GHz by a transmission line technique. The design frequency can be used for satellite communication applications.

This paper examines the effects of metallic semi-rimmed spectacles on the specific absorption rate (SAR) inside the head when illuminated by a frontal dipole source representing a PDA held in front of the face. The frequency considered is 900MHz. Both children's and adult's spectacles are investigated using the Loughborough SAM (Specific Anthropomorphic Mannequin) head incorporated into a DASY4 robot measurement system. The spectacles are tested with and without their arms. For comparison, simulations of the SAM head using FDTD have been conducted. Results show children's semi-rimmed spectacles may be resonant at 900MHz and may have a focusing effect that redistributes the SAR in the head.

Using 802.11b as a bearer this paper presents a simple one dimensional mobility model for the evaluation of fall-back communications protocols in medium range point to point communications systems. The technique provides link state data and is based on radio communication between carriages in a lift. Example throughputs for 802.11b are presented. Applications are Ad-hoc networks and in particular machine to machine radio propagation and assessment of link state assess probabilities in ad-hoc.

This paper deals with perturbations caused to the matching of a simple generic square planar patch in close proximity with a human male torso and a rectangular box phantom filled with tissue simulating liquid. The operating frequency is 1.8GHz and the isolated variable is return loss (S 11 ). Results presented here are useful in assessing optimal antenna/body separation for wearable antennas in Body Area Networks using both intra and inter wireless connectivity. Research indicates that a flat section phantom will tend to produce an optimal return loss closer to its surface than an actual human test subject.

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.

This paper proposes a flexible wearable ultra-wideband antenna suitable for 802.15.3a WPAN applications. The design contains a notch at 5.2 GHz for HIPERLAN compatibility. A novel neoprenecopy substrate is introduced in this paper. Measured results are included for "Antenna on skin" and "Antenna on a hand glove" for return loss and far-field patterns.

This paper investigates Specific Absorption Rates (SAR) in the human head due to partial metallic gap loops (incomplete circular jewellery rings) at 1800 MHz. A Finite-Difference Time-Domain (FDTD) code was used to analyse different sizes and positions of circular rings with a section removed, near a homogenous cubic phantom with a dipole excitation. These partial loops significantly increased the SAR. Measurements from a DASY4 measurement system as well as commercial code results are used for validation. The FDTD code has also been used to analyse the effects of metallic jewellery gap loops when added to the nose of an anatomically realistic digital human head with a realistic source. A monopole on a box was placed in front of the face to represent a PDA. The gap loops on the nose of the realistic head behaved similarly to those near the cubic head. Gap loops of different sizes resonated when their orientation were changed. This means that smaller sizes of jewellery, in certain geometries, may resonate when used with mobile communications equipment than was previously expected.

This paper investigates specific absorption rates (SAR) in the human body with a realistic mobile phone source positioned in a 'front trouser pocket' of a truncated male heterogeneous anatomical body model. A finite-difference time-domain (FDTD) code was used to analyse the SAR in the body in the mobile communication frequency range 0.9 to 4 GHz. Realistic everyday metallic objects, including a coin, a ring and a zip were added to the model. These objects increased the SAR in the body at different frequencies. The cumulative effect of the three objects generally increased the SAR in the waist section over the frequency range considered.

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.

This paper has used the finite-difference time-domain (FDTD) computer simulation technique to investigate specific absorption rates (SAR) in different human head models with metallic jewellery. A dipole excitation has been placed in front of the nose of 4 anatomical heads including a 5 year old and a 12 year old child's head. Metallic tongue jewellery and orthodontist metallic braces were added to the models and the SAR was investigated over a range of communication frequencies.

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.

This paper presents simulated and measured results of a study examining the effects of metallic spectacles on the specific absorption rate (SAR) inside a modified specific anthropomorphic mannequin (SAM) head when using various RF sources. We consider dipole sources resonating at 900 MHz and 1800 MHz as well as three communications enabled PDAs operating in the GSM900 band.

This paper investigates specific absorption rates (SAR) in the human head due to circular metallic earrings at 1800 MHz. A finite-difference time-domain (FDTD) code was used to analyse different sizes and positions of circular earrings near a homogenous cubic phantom. Results showed good agreement with measurements using the flat section of the SAM twin phantom with the DASY4 measurement system. The excitation was a half wave dipole. Metallic loops with a circumference of approximately one wavelength and positioned 14 mm away from the phantom increased the 10 g SAR by 5 times. The FDTD code has also been used to analyse the effect of metallic earrings when 'pierced' through the ear of an anatomically realistic digital human head based on the visible human project. The head is not symmetric and both ears were considered to allow comparison between different heads. The shape of the ear and the size of the earring were found to be very significant when earrings were hung from the human ear.

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.

The paper presents the use of the pulse position modulation (PPM) index, /spl beta/, and pulse doublets for spectral line suppression on PPM time hopping impulse radio (TH-IR) ultra wideband (UWB) systems. We define a pulse doublet as a pulse waveform formed by two identical base pulses, with opposite polarity, separated by a fixed time, T/sub D/. It is shown that, by properly choosing the values of /spl beta/ and T/sub D/, a good number of the spectral lines present on the power spectral density (PSD) can be effectively eliminated. In the example presented, the time hopping code is not considered as it also can help to improve the PSD.

We consider a motorway environment with associated high mobility and compare and contrast position-based and non-position-based routing strategies in reactive ad-hoc protocols. The performances of dynamic source routing (DSR) and ad-hoc on-demand distance vector routing (AODV), for non-positional algorithms, and cluster-based location routing (CBLR), for positional algorithms, are considered. First, for small-scale networks, we have validated our simulation model with the results of a test bed. Then, through simulations, our model is compared with two prominent reactive routing algorithm models for large-scale networks: AODV and DSR. Finally, vehicle mobility on a motorway using a microscopic traffic model developed in OPNET is used to evaluate average route discovery (RD) time, end-to-end delay (EED), routing load, routing overhead, overhead, and delivery ratio.

We present a new cluster-based location routing (CBLR) algorithm for vehicle to vehicle communication. We have evaluated the performance of two reactive (non-positional-based) routing algorithms, dynamic source routing (DSR) and ad-hoc on-demand distance vector routing (AODV), and one positional-based approach, cluster-based location routing algorithm (CBLR). A microscopic traffic model, developed in OPNET, has been used to simulate the mobility of the vehicles on a motorway. Finally, several metrics have been considered to evaluate the performance of the algorithms. Results show that clustering improves scalability and the nature of position-based routing algorithms such as CBLR can improve the performance of AODV and DSR in terms of EED and delivery ratio.

We present a comparison of routing strategies for exchanging information between vehicles. There are two main aspects that are of interest in this work: the comparison between routing strategies (position-based and non-position-based) in highly mobile environments and the improvement of scalability using cluster-based algorithms. We have evaluated the performance of two reactive (non-position-based) routing algorithms, DSR and AODV, and two position-based approaches, LORA and CBLR. We have simulated the mobility of the vehicles on a motorway using a microscopic traffic model developed in OPNET. A scenario was evaluated (three lanes per direction) in terms of average route discovery (RD) time, end-to-end delay (EED), and delivery ratio. Results show that clustering improves scalability when the number of nodes increases and the nature of location information of LORA and CBLR improves the results of AODV and DSR in terms of EED and delivery ratio.

Bluetooth is a typical short-range radio packet ad-hoc technique that is attractive in the rapid formation of a personal area network and inter-connection of different portable mobile devices. Compared with many high-speed wireless LAN techniques, Bluetooth provides a moderate link speed because each link is only allocated with 1 MHz bandwidth. In order to increase the link utilization, Bluetooth introduces the flexible usage of asymmetric link capacity allocation. It means different speeds are allowed in two directions of a link that flow from the master to the slave and from the slave to the master. Because of this, it is possible for Bluetooth to adaptively adjust the link capacity distribution to increase the link performance with lower latency. In this paper, we use the delay cost function to analyse the capacity assignment for a Bluetooth link. Although it only focuses in solving the capacity assignment of a single link, it is also applicable to large-size multi-link and multi-hop networks. It could be extended to generic data networks with asymmetric links.

Unlike most wireless techniques, Bluetooth uses time division duplex (TDD) to arrange the transmission slots so that it can avoid the collisions. In a Bluetooth piconet, a master node coordinates up to seven active slave nodes, which implies up to fourteen different active virtual links. The schedulers of the devices, especially the one in the master node, are in charge of all the transmission disciplines. Therefore, the policy of the scheduler will affect the networks performance of the piconet, like delay and throughput. Currently the Bluetooth scheduler uses a round robin policy to distribute the slots for different links. An enhancement scheme is presented by introducing the predictive link capacity assignment plus the multi-slot framing. The advantages of the corresponding methods is discussed, which lead to a possible practical design of a new scheduler that exploits a better performance of a Bluetooth piconet.

Research into mixed services in mobile cellular networks is highly topical. However, to date, the analytical facility has been limited by the absence of closed forms for the random access (RA) protocols that are pervasive in mixed voice and data systems with a finite number of sessions. We research an RA protocol based on S-ALOHA with data as a session for mobile TDMA cellular networks and present an analytical framework. The paper begins with a general model description of a voice and data subsystem in which admission protocols are explained. An analytical framework is derived. An algorithm is then formulated that complements the analytical framework. The analysis is based on equilibrium-point-analysis (EPA) and is novel and topical. Numerical results are corroborated using a simulation in OPNET.

Medium access control (MAC) is an intermediate layer to manage the policy of link transmissions so that nodes in the same network segment can send packets without constant interference from other nodes. It should give each node the opportunity to transmit packets successfully. Most existing wireless LAN techniques use contention-enable MACs, which are statistical multiplexing algorithms to control multiaccess. Compared to them, regular division-based MACs, such as time division multiplexing (TDM) or frequency division multiplexing (FDM), are seldom used in wireless LANs due to the inefficiency that is shown by the inflexible dynamic bandwidth allocation to nodes. Quality of service (QoS) takes into account this inflexibility in resource reservation in order to grant enough resource to services, even when they are idle. As a result, link connection-oriented networks with mesh topology are considered a good research topic. The corresponding simulation model is required where most current simulation tools do not provide one directly. We present a simple link connection-oriented network simulation design in C without using any existing simulation packages. It can help researchers to design the overall simulation in other related areas, and later it could be extended to a complete simulation tool.

The emergence of new technologies brings alongside innovative characteristics and, therefore, different requirements to the ones already defined in established technologies. This was evident with the appearance of wireless networks and the introduction of the mobility concept. Existing systems were created to work in a fixed and sometimes portable environment and, although it is possible to apply them in a wireless mobile environment, it is foreseen that they will have an impact in the performance and functionality of the system, threatening the absolute usability of the advantages provided by this new technology. This document presents the results of the experiment to quantify the latency introduced by the IP security protocol and introduces the mobile secure communication channel (MSCC), a novel protocol that provides the services of registration request authentication, key exchange, integrity, data origin authentication, anti-replay protection and confidentiality for the established of a secure communication channel in a wireless mobile environment, therefore representing a first step towards the achievement of secure seamless mobility.

This paper researches a random access (RA) protocol based on S-ALOHA with capture mode with a class of data that consists of a finite number of open sessions with a general distribution for mobile TDMA cellular networks and presents an analytical framework. The channel is shared in mixed voice and data. The work considers users that contend in the uplink using the RA protocol based on S-ALOHA and contention takes places every N/sub c/ frame. The analysis is based on equilibrium-point-analysis (EPA) and is novel and topical. Numerical results are corroborated by simulation.

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.