Radio communication method in traffic system, radio base station, and radio terminal

Abstract

A vehicle-mounted unit (20) sends (at S103) an assignment request for radio resources to a road-side unit (10B). This road-side unit (10B) assigns (at S104 and S105), when it receives that assignment request, road-vehicle resources or radio resources for road-vehicle communications with the vehicle-mounted unit (20) and vehicle-vehicle resources or radio resources for vehicle-vehicle communications between the vehicle-mounted units (20), and sends (at S106) the assignment information to the vehicle-mounted unit (20). The vehicle-mounted set (20) performs (at S110 and S111) the road-vehicle communications with the road-side unit (10B) by using the road-vehicle resources recognized by the assignment information received from the road-side unit (10B), and performs (at S112 to S115) the vehicle-vehicle communications with another vehicle-mounted set (20) by using the vehicle-vehicle resources discriminated with that assignment information. As a result, the road-vehicle communications and the vehicle-vehicle communications of high utilizing efficiencies of the radio resources can be realized while avoiding the 'hidden terminal problem'.

Description

technical field [0001] The present invention relates to a wireless communication method, a wireless base station and a wireless terminal in a traffic system, for example, relates to a technology suitable for realizing an ITS (Intelligent Transport System) such as a WiMAX system that uses OFDMA for road-to-vehicle and vehicle-to-vehicle wireless communications. Background technique [0002] In recent years, in order to reduce traffic accidents, development of an intelligent transport system (ITS: Intelligent Transport System) has been progressing. As an ITS, there is a form of road-to-vehicle communication in which a signal has a wireless base station (roadside device) and transmits signal information (red or Green, etc.) and information on whether there are right-turning vehicles, etc. [0003] On the other hand, in recent years, as a medium-distance large-capacity wireless communication system, a wireless communication system of the OFDMA (Orthogonal Frequency Domain Multi...

AI Technical Summary

Problems solved by technology

[0024] In this way, the CSMA method is an asynchronous communication method, so when a plurality of wireless terminals transmit at the same time, it is not clear when it is possible to transmit.

In addition, in the CSMA method, there are unavoidable problems such as the so-called "hidden terminal problem", and it is unclear whether reliable communication can be performed

That is, although it is possible to communicate with a public access point, when a wireless terminal at a location where a signal from one cannot reach the other due to the presence of an obstruction or the communicable distance (this is called a "hidden terminal") When both send and receive to the same access point at the same time, the sending signals of both parties conflict, and the access point cannot receive normally.

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