ITS (Intelligent Transport Systems) wireless communications system has been developing based on the leading edge ICT (Information Communication Technologies) in Japan. The comfort driving systems for example VICS (Vehicular Information Communication system), ETC (Electronic Toll Collection), Telematics has already become popular and the safety driving support systems, such as ASV (Advanced Safety Vehicle) and SMARTWAY have been scheduled for introduction in the near future. However, there are many residual issues in the comfort driving system because of the existence of the traffic jam and the interest of the economical cars in the world. Moreover, the acceleration of the development of the Smart Grid and EV (Electric Vehicle) would affect the future development of the ITS wireless communications system. In this paper, it is clarified that the future development should be advanced considering the one of the basic business rule of 'market-in and product-out'.

This paper propeses advanced multi-stage interference canceller systems (MSICS) wihch can estimate radio channels with precision in the direct sequence code division multiple access (DS-CDMA) systems. For the accurate channel estimations, we propose a novel radio channel estimation method specified by the following two signal processing methods. One is the radio channel estimation using both pilot and information signals. The other is the correction of estimated radio channels using adaptation algorithm based on the least mean square method (LMS). The results of our computer simulation indicate that the cell capacity of the advanced MSICS in serial and parallel structure can be increased by about 1.8 and 1.3 times over that of a receiver which does not has a canceller, respectively. Moreover, the advanced MSICS in serial and parallel structure can reduce the required Eb/No by about 1.2 dB and 1.6 dB at a BER of 10-3 compared to the Eb/No of a basic MSICS, respectively.

This paper describes the performance analysis of a distributed antenna system which includes space and path diversity with radio channel estimation. This system is used for CDMA personal communication systems. In this paper, the performance of a diversity system is analyzed precisely considering multipath and inter-antenna interference. In a diversity system, the adaptive RAKE receiver which estimates the characteristics of a radio channel adaptively has been used for diversity combining. In the adaptive RAKE, the time-variant characteristic has been approximated by a time function. In this paper, the estimation performance of the adaptive RAKE is analyzed in cases of time functions of 0-th, first and second degrees. The performances are evaluated and compared with the differential RAKE. The adaptive RAKE is found to improve the signal quality of more than 2dB in comparison with the differential RAKE. It is also found that the optimum parameter design can be achieved flexibly for radio channel estimation by using higher degree time functions.

We have developed an IP-over-Ethernet-based ultra high-speed multimedia wireless LAN prototype operating in the 60-GHz band. It employs a media-access-control (MAC) protocol based on reservation-based slotted idle signal multiple access (RS-ISMA), which was implemented in the former prototype, for supporting various IP traffic such as real-time AV traffic and best-effort web traffic. The protocol also has a new function called NACK sensing for the efficient retransmission of wireless multicast packets. It was demonstrated that the prototype can provide the world's fastest radio transmission speed of 128 Mbps for two-way communications. We have measured the throughput and latency of the prototype LAN for Ethernet-frame transmission in a point-to-point baseband-connected environment. The measurement showed that the prototype LAN provides a maximum throughput of 30 Mbps, and that the measured throughput agrees with the theoretically predicted throughput. It also showed that the maximum latency, which includes switching and routing latency in the wired part, is below 1 msec.