KR100393785B1 - Communication frame size variable method for dedicated short range communication system - Google Patents

Abstract

The present invention relates to a method for changing a communication frame size of a short-range wireless dedicated communication system, and more particularly, to improve transmission efficiency by varying the length of a communication frame between a DSRC base station and a DSRC terminal according to a transmission efficiency of a wireless channel. According to an aspect of the present invention, there is provided a data communication method between a DSRC terminal and a DSRC base station, comprising: a first step of checking a transmission efficiency of a radio channel with a DSRC terminal at a DSRC base station; A second step of setting a length of a communication frame composed of a plurality of data slots at a base station to a normal length; and in case the transmission efficiency of a wireless channel is poor, varying the number of data slots forming a communication frame at the DSRC base station And performing a third step of setting to do so.

Description

Communication frame size variable method of short-range wireless communication system {COMMUNICATION FRAME SIZE VARIABLE METHOD FOR DEDICATED SHORT RANGE COMMUNICATION SYSTEM}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intelligent transportation system, and more particularly, to a method for changing a communication frame size of a short-range wireless communication system.

As the number of vehicles increases, wireless communication technology is integrated into traffic-related systems in order to suppress traffic congestion and the increase in logistics costs.

Conventionally, FM-DARC wireless communication, beacon wireless communication, cellular wireless communication and IMT-2000 wireless communication have been proposed as a wireless communication technology for incorporating traffic related systems.

The FM-DARC wireless communication method is a method of transmitting digital data using an existing FM broadcast channel. Since the transmission speed is up to 16kbps and the communication cell size is several tens of Km, the digital transceiver is implemented because it uses a wide area service and an existing broadcast channel. There is an easy advantage.

The beacon wireless communication method can provide convenience to the user through automatic parking fee settlement and parking available location designation when using the parking service because the two-way communication between the vehicle terminal and the roadside base station is possible.

The cellular wireless communication method uses a circuit communication method for providing a voice service to a vehicle driver even when moving.

The IMT-2000 wireless communication method is being developed as a communication method capable of providing a packet data service as well as a voice service.

However, the conventional technology using the FM-DARC wireless communication method is limited by the one-way service provided only downlink because it uses a broadcast channel, and the technology using the beacon wireless communication method supports multiple vehicle terminals and multiple accesses. Therefore, when two or more terminals simultaneously access a wireless channel in a cell, a link setup is not performed.

In addition, the technology using the conventional cellular wireless communication method increases the service cost because the user must keep the call state to receive information, and the technology using the IMT-2000 wireless communication method has a frequency bandwidth according to the service provided There is a problem that the frequency should be changed according to the service desired by the user.

In order to improve the above problems, an intelligent transport system (ITS) has been proposed, and it can be classified into public transportation system, traffic management system, cargo transportation system, traffic information system, vehicle and road system according to the application field. have.

The intelligent traffic system implements a dedicated system to provide various services through the collection and distribution processing of traffic information in real time. As an example, a dedicated short range communication (DSRC) system is proposed.

The DSRC system can accommodate various traffic services in one vehicle terminal, provide high speed packet communication by providing a stable data channel, communication in a narrow communication area and efficient use of radio resources, and voice synthesis. It provides a simple user interface for short text / image display, keypad input devices, and IC cards.

However, in the conventional DSRC system, since the communication frame between the DSRC base station and the DSRC terminal is transmitted in a fixed form without considering the communication environment, the transmission efficiency is further deteriorated when the BER (Bit Error Rate) is bad. there was.

Accordingly, the present invention is to improve the transmission efficiency by varying the length of the communication frame between the DSRC base station and the DSRC terminal in accordance with the transmission efficiency of the radio channel in order to improve the conventional problems, the communication frame size in the short-range wireless dedicated communication network The purpose is to provide a method.

That is, an object of the present invention is to transmit data continuously by setting a frame size to a prescribed normal length when the bit error rate (BER) is good when performing wireless communication between the DSRC base station and the DSRC terminal, and conversely, the bit error rate is bad. In this case, the frame size is changed to a short form to improve transmission performance according to a retransmission request.

1 is a block diagram of a general DSRC system.

2 is an exemplary view showing the size of a communication frame in an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100: DSRC terminal 200: DSRC base station

400: DSRC Server

The present invention provides a data communication method between a DSRC terminal and a DSRC base station in order to achieve the above object, the step of checking the transmission efficiency of the radio channel with the DSRC terminal in the DSRC base station, when the radio channel transmission efficiency is good Setting a length of a communication frame consisting of a plurality of data slots in the DSRC base station to a normal length, and varying the number of data slots forming a communication frame in the DSRC base station when the transmission efficiency of the wireless channel is poor. Characterized in that the step of setting to perform.

In the above, the transmission efficiency of the wireless channel is determined from a bit error rate (BER) or a retransmission probability due to a transmission error.

As the transmission efficiency of the radio channel becomes worse, the partitioning of the plurality of data slots is further divided to improve retransmission performance.

Hereinafter, the present invention will be described in detail with reference to the drawings.

In general, as shown in the configuration diagram of FIG. 1, a DSRC system is installed in a vehicle and transmits relevant vehicle-related information and displays service information requested by a driver. Is installed and the DSRC base station 200 for two-way wireless communication with the DSRC terminal 100, and collects and manages the transmission information from the DSRC base station 200 through the DSRC dedicated network 300 from the DSRC terminal 100 Service information corresponding to the service request of the configuration through the DSRC base station 200 to the DSRC terminal 100 to the DSRC server 400. ]

The DSRC terminal 100 is configured as an additional display device for displaying the service information provided from the DSRC server 400, for example, an LCD monitor.

The DSRC terminal 100 is configured to record a unique registration number and vehicle-related information by embedding a smart card, analyze the information, and transmit the same to the DSRC base station 200 by its own power transmission function.

The DSRC base station 200 can transmit data with the vehicle terminal 100 at a high speed of up to 1 Mbps, and a plurality of vehicle terminals (eg, eight) with one frequency using a TDMA scheme to increase channel utilization effects. It can communicate at the same time and is configured to perform near field communication using Industrial, Scientific and Medical (ISM) band frequencies and low power RF.

In the embodiment of the present invention, the configuration of the DSRC system is the same as that of FIG. 1, but the communication frame is variable in the DSRC base station 200 according to the state of the communication channel in the bidirectional communication between the DSRC terminal 100 and the DSRC base station 200. It is configured to determine.

Referring to the operation and the effect of the embodiment of the present invention as follows.

First, when a vehicle equipped with the DSRC terminal 100 enters the communication range of the DSRC base station 200, the DSRC terminal 100 receives the ETC broadcast signal transmitted from the DSRC base station 200 and transmits the ETC broadcast signal. Analyze and use the available channel to the DSRC base station 200.

The DSRC base station 200 transmits usable channel information to the DSRC terminal 100 and the DSRC terminal 100 transmits registration information (including a unique registration number) recorded in the smart card to the DSRC base station 200. do.

In this case, the DSRC base station 200 receives the vehicle-related information, and transmits the received data to the DSRC terminal 100 whether it is normally received. The DSRC terminal 100 stores the transmission history of the vehicle inspection data and stores the same data in the same region. Do not send duplicates.

The DSRC base station 200 transmits this information to the DSRC server 400 via the DSRC dedicated network 300 to confirm the registration information of the DSRC terminal 100.

The DSRC server 400 performs authentication on a request for confirming registration information for the DSRC terminal 100 from the DSRC base station 200 and transmits the availability to the DSRC base station 200.

Therefore, when the DSRC terminal 100 is authenticated as available, the DSRC base station 200 performs the bidirectional communication with the DSRC terminal 100 and transmits the vehicle-related information collected from the DSRC terminal 100 to the DSRC dedicated network 300. It transmits to the DSRC server 400 via.

The DSRC server 400 collects and manages vehicle-related information transmitted from the DSRC terminal 100 and transmits corresponding information to the DSRC base station 200 when there is a service request of specific information from the DSRC terminal 100. It will be provided to the DSRC terminal 100.

Meanwhile, the DSRC base station 200 varies the communication frame structure according to the transmission efficiency of the wireless channel while performing bidirectional communication with the DSRC terminal 100. This will be described with reference to FIG. 2.

The DSRC base station 200 determines the transmission efficiency of the wireless channel by checking the bit error rate (BER) while performing bidirectional communication with the DSRC terminal 100.

In this case, the DSRC base station 200 checks the bit error rate (BER) in software to check the status of the radio channel with the DSRC terminal 100 or the same information by the radio channel error to the DSRC terminal 100. Use the method of checking the probability of retransmission.

First, when it is determined that the transmission efficiency of the radio channel is good, the DSRC base station 200 is configured to receive information related to the size (regulated normal length) of the communication frame in the normal mode which is mutually agreed with the DSRC terminal 100. Transmit to the DSRC terminal 100.

The DSRC terminal 100 receives its time slot from information related to the size of the communication frame in the DSRC base station 200 and transmits frame data.

In other words, when the transmission efficiency of the radio channel is good, a communication frame having a normal length as shown in the example of Fig. 2A is used.

On the contrary, if it is determined that the transmission efficiency of the radio channel is poor, the DSRC base station 200 transmits information for varying the number of data slots multiplexed in the communication frame to the DSRC terminal 100.

In this case, the information related to the size of the communication frame is information for dividing the data slot multiplexed in the communication frame according to the state of the radio channel. As the transmission efficiency of the radio channel worsens, the data slot is further divided.

That is, when the transmission efficiency of the wireless channel is poor, the length of the communication frame is variable and used as shown in the example of FIGS. 2 (b) and (c).

The DSRC terminal 100 checks the information related to the size of the communication frame transmitted from the DSRC base station 200 to allocate the available time slot and transmit the frame data in the corresponding time slot.

As described in detail above, the present invention has the effect of reducing the retransmission operation due to transmission error of the frame data by variably operating the size of the available communication frame according to the transmission efficiency of the radio channel.

In addition, the present invention does not need to provide a device for measuring the bit error rate (BER) by reducing the operating cost by interworking with the bit error rate (BER) test method defined by the communication protocol between the DSRC base station and the DSRC vehicle terminal period. It can be effective.

Claims (4)

A data communication method between a DSRC terminal and a DSRC base station, comprising: a first step of checking a transmission efficiency of a radio channel from a DSRC base station to a DSRC terminal; and when the transmission efficiency of the radio channel is good, a plurality of data slots in the DSRC base station The second step of setting the length of the communication frame consisting of a normal length, and the third step of setting the variable number of the plurality of data slots constituting the communication frame in the DSRC base station when the transmission efficiency of the wireless channel is poor in the Method of varying the communication frame size of a short-range wireless communication system, characterized in that for performing The method of claim 1, wherein the transmission efficiency of the wireless channel is determined from a bit error rate (BER). The method of claim 1, wherein the transmission efficiency of the wireless channel is determined based on a probability of retransmission due to a transmission error. The method of claim 1, wherein the retransmission performance is improved by subdividing the partitioning of the plurality of data slots as the transmission efficiency of the wireless channel becomes worse.