In order to shorten service time in a shop by drive-through use, ITS services are required whereby ordering goods in advance in-vehicle use, then fee payment and goods receipt at a drive-through booth lane are performed. In this paper, we propose a system via DSRC that combines prior order using IP connection by a car navigation system with order decision and payment processing in a shop. As a result of the field tests in the actual drive-through shop, service time in drive-through use and users’ waiting time could be shortened and the effectiveness of the system has been confirmed.

View full abstract

In this letter, a design method of a simple decoupling network (DN), which decouples adjacent antenna ports for n-element linear array antenna, is presented and evaluated based on simulation and measurements. In our technique, microstrip line (MSL) is used to configure DN. MSLs work as bridge susceptances and are connected between two adjacent antenna ports, and they decouple the antenna ports by means of cancelling the mutual admittance. From the experimental results, it is found that the mutual coupling less than -30dB between adjacent antenna elements is achieved by using proposed design method.

View full abstract

A pseudo error based performance monitoring technique is studied in this paper to monitor the primary communications for the cognitive radio networks. We firstly introduce the pseudo error based monitoring method and then apply the monitoring method to the cognitive radio networks. Simulation results show that the primary communications can be monitored very well by using the scheme in term of the coverage percentage under the practical channel. In particular, the robustness of the scheme to the interference is also revealed by comparing with the energy detection.

View full abstract

One of the serious problems in the conventional transmission system, which uses the Neutral and Live (N-L) conductors, for the Narrow-Band Power-Line Communications (NB-PLC) is the low Signal to Noise Ratio (SNR) property. To improve it, a new signal transmission system, which uses the Protective Earth (N-PE) conductor instead of L, has been proposed in this letter. The proposed method is called N-PE system. The results show that the receiving SNR, the channel capacity, and the Packet Reception success Rate (PRR) values of the N-PE system were superior to those of the N-L system, except for the noise property.

View full abstract

We propose a three-element Yagi-Uda antenna with an inter-element spacing of 0.025 wavelengths for intelligent transport systems (ITS) in the ultra-high frequency (UHF) band. The Yagi-Uda antenna has a reflector dipole with a transmission line at the center. We show by numerical simulation that the antenna can be placed at the contact limit of a vehicle body with improved performance when the transmission line has a meandering configuration. Further, we show by experiment that the actual gain improves by approximately 2dB when the antenna is placed near a conducting plate.

View full abstract

This letter proposes a routing scheme to send a data set in units of bits rather than bits/s by considering the predefined transfer time, the period within which the data set should be transferred from the source node to the destination node, to minimize the energy consumed. The energy consumption is minimized with an optimal transfer time. The results show that routing at the optimal transfer time is, for the data set being sent, able to reduce energy consumption at least 7.7% for the networks examined.

View full abstract

In space communication environment, Vegas congestion control algorithm provides better performance than TCP Reno algorithm. Thus Vegas algorithm is usually used in satellite communication networks, which have long delay, high Bit Error Rate (BER) and so on. However, existing Vegas algorithm does not provide satisfactory performance in slow start stage or congestion avoidance stage in space communication environment. In this paper, an enhanced Vegas congestion control algorithm has been suggested to overcome such problems. Then, simulation of the traditional Vegas algorithm and the enhanced Vegas algorithm has been dealt with in geostationary orbit satellite model and BeiDou navigation system model using Network Simulation 2 (NS2) software. The simulation results show that, the enhanced Vegas congestion control algorithm can achieve significant performance improvement.

View full abstract