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Body area networks (BAN) will become increasingly important in the future personal communication systems. We believe that intra-body communications (IBC) based on near field electromagnetic waves is a suitable solution for BAN. This paper presents experimental measurements of the frequency and time domain responses in order to investigate the transmission characteristics of the human body as a conductor of low power high frequency radio signals (up to 3GHz). In the measurements, several distances between transmitter and receiver (up to a long distance from the head to the foot) and six test people (to study the possible variation results due to physiological body effects) have been considered. Besides analyzing the intra-body channel response, we also aim to define a suitable frequency range for IBC. Finally, this paper also presents an initial evaluation study of several digital modulation schemes in order to investigate the optimal technique for IBC.

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This paper proposes a hybrid communication system for Intelligent Transportation System (ITS) utilizing visible light and radio communications for position-based services. The directionality of light communication is used to distribute positionbased keys to vehicles such that they can extract information related only to their desired lanes. The extended coverage of radio communication is used to provide stable data communication complementing the visible light communications (VLC) systems. This paper provides system models and important parameters for designing a hybrid ITS system. The system performance is evaluated by simulation, and the results demonstrate a considerable increase of the effective communication area and receivable information using the proposed hybrid ITS system compared with a VLC system. I. INTRODUCTIONIntelligent Transportation Systems (ITS) has been motivated by the need for reducing traffic congestion and offering better user experience in navigation and location-specific services. In general, ITS can be combined with data transmission technology, real-time control technology, and data-mining technology for providing efficient traffic and data communication simultaneously. By reducing the average travel distance and waiting time of each vehicle, hence their carbon emission, ITS also helps prevent the global warming [1]- [2].Recently, visible light communication (VLC) has drawn a lot of attention. ITS is one of its most important applications. The use of VLC in ITS has several advantages over the conventional use of radio-frequency (RF) communication. First, light-emitting diodes (LED), which have been widely deployed in traffic lights, can be used as VLC transmitters. Second, VLC allows more precise positioning of the vehicles because light travels in a straight line [3]. In addition to these two advantages, there is a third advantage which has received less attention in the literature: lane-specific communication. VLC can combine the features of positioning and data transmission, in the sense that the receiver can detect not only the data, but also the physical position of the source transmitting the data. In ITS, this allows the receiver at the vehicle to decode and to display to the driver only that traffic information which is relevant to the lane which the vehicle is in. Then the driver will not be bothered with traffic information irrelevant to him (e.g. those only relevant to neighboring lanes) and the user experience is improved. In this work, we consider the feature of lane-specific communication as a necessary requirement.Nevertheless, it is well known that VLC cannot compete with radio frequency (RF) systems when it comes to longdistance transmission. This is an important concern in ITS

Intra-body communications is becoming a promising solution for Body Area Nefworks with a lot of interesting potential applications towards a ubiquitous communication world. Our research is based on the neurfield radio. wherein electromagnetic radio signals are transmitted through the human bo& from a transmitter to a receiver. In contrast with current studies, we aim to study the transmission characteristics of the human body as a conductor of radio signals with higher frequency carriers (up to 1400MNz) in order to find an optimal frequency range for implementing, at last, broadband intra-bo& communications with high data rates. To achieve our j h i goal, we carry out experiments where we investigate the delay time proJle and the attenuation of the received signal.