Several contention-based Medium Access Control (MAC) protocols have been proposed for the vehicles to gain the radio channels to distribute active safety messages timely, e.g., Safety Critical Application (SCA) information, for inter-vehicle communications in Vehicular Ad Hoc Networks (VANETs). In these MAC protocols, a contention period is introduced before the vehicle for channel access so that we may not have the timely and reliably message dissemination in VANETs. To reduce the contention period, this paper proposes a Region-based Clustering Mechanism (RCM) to be applied in these MAC protocols. We propose analytical models to investigate the performance of the RCM, which are validated by the simulation experiments.

The finite-impulse response (FIR) filter technique has been widely used for pre-emphasis of channels to mitigate the intersymbol interference (ISI) resulted from both frequency dependent losses and reflections. This paper proposes a systematic methodology, based on arbitrary step response, to determine the tap setting of multi-tap FIR filter for best eye diagram improvement. The required tap number and the optimal tap coefficients are determined according to the compensation efficiency and hence the ultimate performance of FIR filter is evaluated. Eventually, the compensation results for two specific 5 Gbps signalling systems, which include significant effects of losses and multiple reflections are demonstrated to validate the optimization method.

Radio frequency identification (RFID) is a popular technology, but some problems still need to be overcome. Hopper and Blum proposed a light-weight authentication protocol, HB protocol, which is especially suitable for devices with low computation ability such as passive RFID tags. Later, HB protocol was proven to be insecure, and Munilla and Peinado amended it by proposing HB-MP and HB-MP protocols. However, only the tag is authenticated by the reader in these protocols. In this paper, we will present an enhancement of the HB-protocol family with mutual authentication to have only the legal reader obtain the legal reader's data. The proposed protocol is light-weight because only scalar dot product operation of binary vectors and XOR operation are adopted. Moreover, it is computational secure since its security is based on solving LPN problem, an NP-complete problem.

3GPP 23.246 proposed the multimedia broadcast multicast service (MBMS) to deliver multicasting content in the Universal mobile telecommunications system (UMTS). In MBMS, the common logical channel is enabled to serve multiple MBMS calls at the same time. Use of the common logical channel may cause interference to the dedicated logical channels serving the traditional calls. To more efficiently utilize the radio resource to serve both traditional and MBMS calls, this paper proposes two channel allocation algorithms: Reserved Resource for Multicasting (RRM) and Unreserved Resource for Multicasting (URM). We propose analytic models and conduct simulation experiments to investigate customer Satisfaction Indication (SI) for the two algorithms. Our study indicates that URM outperforms RRM in terms of customer SI.

Abstract Recently, mobile networks and internet technologies have been widely developed for the voice communication and information retrieval services all over the world. Compared with the wire‐line internet environment, mobile networks have lower bandwidth, longer transmission latency and unreliable connection, and the capability of mobile terminals is restricted by the limited memory size, lower CPU computation capability and inconvenient I/O interface. These limitations restrict the development of the wireless internet applications. In this paper, we design and implement a ‘wireless internet remote access platform’ (WIRAP). The WIRAP platform interconnects the wireless network and internet to provide mobile users a remote centralized storage and computation environment. A mobile user can store large volume of data and execute complex computations on WIRAP instead of on the mobile terminals. WIRAP supports different network interfaces (e.g. short message service (SMS), wireless markup language (WML) and hyper text markup language (HTML) and users may use terminals (with different network capabilities) to access WIRAP. Copyright © 2006 John Wiley & Sons, Ltd.