JPH088876A - Radio communication system - Google Patents

Abstract

PURPOSE:To surely transmit data to a reception terminal far away by discriminating the kind of a reception packet from a communication terminal and transmitting a broadcasting packet to a radio channel when the reception packet is the broadcasting packet. CONSTITUTION:A data terminal 5 is installed within a range where radio waves from a repeater station 7 reach and is capable of surely performing reception and the other data terminals 3, 5 and the repeater station 7 stand by in a previously specified frequency channel. A transmission side radio adapter 2 starts the transmission of a broadcasting data packet, monitors a used frequency channel and then, shifts to a data packet send-out procedure when the channel becomes free. In a radio adapter 4, a transmission destination address in the packet is read and transferred to the data terminal 3. In the repeater station 7, the transmission of the broadcasting data packet is started in the same channel when possibility that the data terminal 5 can not receive the broadcasting data packet is high and broadcasting is completed when all the data terminals 1, 3 and 5 receive the packet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital wireless communication system for transmitting data in packet units, and more particularly to a digital wireless communication system having a relay function.

[0002]

2. Description of the Related Art As digital wireless communication spreads, the number of cases in which data communication is performed by wireless lines has increased.
Generally, terminals directly send and receive data, but when terminals are far apart, it is necessary to send and receive data via a relay station.

There are several types of data packets to be transmitted, and among them, there are broadcast packets addressed to all terminals. Since there are many other terminals at the time of transmitting the broadcast packet, it is difficult to control each terminal to confirm its position. Therefore, conventionally, in the case of a broadcast packet, the relay station is not particularly used when the transmitting side terminal transmits.

[0004]

However, in the above-mentioned conventional example, when the relay station is not used, the broadcast packet cannot be received if the receiving side terminal is located away from the transmitting side terminal. In addition, there is also a problem that many terminals cannot receive the packet because the retransmission control is not normally performed when the broadcast packet is transmitted.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a wireless communication system capable of reliably transmitting data to a receiving terminal far away.

[0006]

In order to achieve the above object, the wireless communication system of the present invention has the following configuration.

That is, in a digital radio communication system comprising a relay station having a data relay function and other communication terminals, the relay station is provided with identification means for identifying the type of packet received from the communication terminal, When the received packet is a broadcast packet, a sending means for sending the broadcast packet to the wireless line is provided.

The radio communication system according to the present invention has the following steps.

That is, in a wireless communication system composed of a plurality of communication terminals including a communication terminal having a relay function, the type of the packet received from the transmitting communication terminal is identified, and the identification result is a broadcast packet. In this case, each step of relaying the broadcast packet to the communication terminal of the broadcast destination by wireless communication is included.

[0010]

According to such a wireless communication system, the type of the packet received from the communication terminal is identified, and if the received packet is a broadcast packet, the broadcast packet is sent to the wireless line to allow a remote communication. Data can be reliably transmitted to the receiving terminal.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing a system configuration of a wireless communication system in this embodiment. In the figure, 1 is a first data terminal, and 2 is a first wireless adapter connected to the first data terminal 1. Reference numeral 3 is a second data terminal, and 4 is a second wireless adapter connected to the second data terminal 3. Reference numeral 5 is a third data terminal, and 6 is a third wireless adapter connected to the third data terminal 5. A wireless adapter 7 functions as a relay station.

In this embodiment, the second data terminal is located near the first data terminal and the third data terminal is located away from the first data terminal.

FIG. 2 is a block diagram showing the internal structure of the wireless adapter and the relay station in this embodiment. The configurations of the wireless adapter and the relay station are the same, and the wireless adapter 2 will be described as an example as shown in FIG.

In the figure, reference numeral 21 is a LAN controller, which controls an Ethernet interface with the data terminal 1 to be connected. Reference numeral 22 denotes a RAM, which temporarily stores transmission / reception data. A CPU 23 controls the entire adapter. A communication controller 24 assembles or disassembles packets. Reference numeral 25 is a bit synchronization circuit (DPLL). A wireless unit 26 includes a modulation or demodulation unit and the like. 27 is an antenna. 28 is a data bus, 29 is a carrier detection signal, and 30 is a channel selection signal.

FIG. 3 is a diagram showing the formats of the control packet and the data packet in this embodiment. In the figure, 31 is a flag, 32 is a destination address, 3
Reference numeral 3 is a source address, and 34 is a packet type of a control packet, which indicates either a transmission request, a reception permission, or a broadcast. Reference numeral 35 is a designated frequency of the control packet, which indicates F1 or F2. 36 is a CRC for error detection, and
37 is transmission data of the data packet.

FIG. 4 is a sequence showing the broadcast processing of the relay station 7 in this embodiment, and FIG. 5 is a flow chart showing the operation of the relay station 7.

The detailed operation of this embodiment will be described below with reference to FIGS.

In this embodiment, a case will be described in which broadcast data is transmitted from the data terminal 1 to the other data terminals 3 and 5 via the relay station 7.

First, when a data transmission request occurs,
Data is sent from the data terminal 1 to the wireless adapter 2.
As described above, the data terminal 1 and the wireless adapter 2 are connected via the Ethernet interface.
Data is transferred to the RAM 22 via the LAN controller 21 in the wireless adapter 2.

At this stage, the wireless adapter 2 needs to notify the other data terminals 3 and 5 of which channel the broadcast data is transmitted. Since the other data terminals 3 and 5 including the relay station 7 are waiting on the predetermined frequency channel 1 (control channel) (step S101),
The wireless adapter 2 uses the carrier detection signal 29 to monitor the usage status of the frequency channel 1. As a result, if the channel is open, the control packet shown in FIG. 3 is transmitted (S1 shown in FIG. 4). The control packet contains the destination address 32 and the frequency channel number 3 used for data transmission.
5 (for example, No. 4), packet type 34 (transmission request,
Information such as reception permission and broadcast request) is included. In this embodiment, since the broadcast communication is performed, the packet type 34 contains the broadcast request data. After the transmission of this control packet is completed, the CPU 23 switches the channel by the channel selection signal 30 and waits on the frequency channel 2.

According to the procedure described above, the data terminal 3 located at a short distance from the relay station 7 and the data terminal 1 on the transmitting side can receive the broadcast request control packet (step S102). The data terminal 5 in use may not be able to receive the broadcast request control packet. Therefore, the relay station 7 starts transmitting the same packet as the received broadcast packet (step S104, S2 shown in FIG. 4). Since the data terminal 5 is installed in a range where the radio wave from the relay station 7 can reach, it can almost certainly receive the broadcast request control packet sent from the relay station 7. Next, the other data terminals 3 and 5 and the relay station 7, which have received the broadcast request control packet, stand by on the previously designated frequency channel 4 (step S105).

In this way, since the other data terminals 3 and 5 and the relay station 7 are ready to receive the broadcast data packet, the wireless adapter 2 on the transmitting side starts transmitting the broadcast data packet (see FIG. 4 shown in S3). In the same procedure as when transmitting the control packet described above, the frequency channel 4 to be used
Monitor usage of. If this channel is in use, wait until the channel is free. Then, when the channel becomes free, the procedure shifts to the data packet transmission procedure. That is, the data of the data terminal 1 that has been sent earlier is read from the RAM 22, and the flag 31, the destination address 32, the source address 33, and the CRC 36 for error detection are added and assembled into a data packet. It is sent to the wireless unit 26. Data indicating that the data is addressed to all data terminals is written in the destination address. Data transmission from the radio unit 26 is started following the preamble signal.

As a result, the wireless adapter 4, which has received the broadcast data packet, reads the destination address in the packet, temporarily stores the data in the RAM 22, and then outputs L.
The data is transferred to the data terminal 3 via the AN controller 21. Also, as in the case of the broadcast request control packet described above, there is a high possibility that the data terminal 5 cannot receive the broadcast data packet at the relay station 7, so when the broadcast data packet is received (step S106), the same channel is received. To start transmitting the broadcast data packet (step S10).
7, S4 shown in FIG. 4). When all the data terminals receive this packet, the broadcast is completed.

On the other hand, in step S102, when the received control packet is not the broadcast request packet, the relay station 7
The other data terminals 3 and 5 receive the packet only when the packet is addressed to itself (step S103). If the control packet is the transmission request packet, the relay station 7 transfers the transmission request packet on the control channel 1 (step S1).
08), the reception confirmation packet is received on the control channel 2 (step S109), and the reception confirmation packet is transferred to the transmission side terminal (step S110). Then, the data packet is received on the data channel (step S11).
1) The data packet is transferred to the receiving terminal (step S112), and if the power is not off, the process returns to step S101 (step S113), and the above-described relay operation is repeated.

As described above, it becomes possible for a data terminal located away from the transmitting data terminal to receive the broadcast packet without fail.

In the present embodiment, the broadcast request is made by the control channel before transmitting the broadcast data packet, but it is not always necessary to make the broadcast request in advance.

For example, even by transmitting a broadcast data packet on the control channel, the same effect can be obtained by performing the operation of transferring the data received by the relay station. By using the control channel, there is an advantage that the broadcast data can be reliably received because another terminal cannot start the transmission during the transmission of the broadcast data packet.

In the present embodiment, it is assumed that the low frequency frequency hopping system is used as the radio channel, but the present invention does not depend on the type of the radio channel at all.
For example, it is possible to use a direct spread method of spread spectrum communication.

Further, in this embodiment, the data terminal and the wireless adapter are separate and are connected to each other via Ethernet, but the data terminal and the wireless adapter have the same configuration even if the data terminal itself has a wireless processing unit. Is possible.

Further, in the present embodiment, the relay station and the data terminal are explained as completely different ones, but for the sake of convenience of explanation, the hardware / software configuration itself is completely common. But there is no problem. It is possible to obtain exactly the same effect by adopting a configuration in which whether or not to perform the relay function is selected by the switch attached to the terminal.

As described above, the relay station has means for identifying the type of the received packet and means for transmitting the broadcast packet to the wireless line when the received packet is the broadcast packet. With the provision, the broadcast packet can be received regardless of the position of the receiving side terminal.

The present invention may be applied to either a system composed of a plurality of devices or an apparatus composed of a single device.

Needless to say, the present invention can also be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0035]

As described above, according to the present invention,
It is possible to reliably transmit data to a receiving terminal far away.

[0036]

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a wireless communication system according to an embodiment.

FIG. 2 is a diagram showing a configuration of a wireless adapter or a relay station according to the present embodiment.

FIG. 3 is a diagram showing a packet format in this embodiment.

FIG. 4 is a diagram showing a broadcast processing sequence of a relay station in this embodiment.

FIG. 5 is a flowchart showing the operation of the relay station in this embodiment.

[Explanation of symbols]

 1 1st data terminal 2 1st wireless adapter 3 2nd data terminal 4 2nd wireless adapter 7 relay station 24 communication controller 26 wireless section

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H04L 12/28 12/18 H04L 11/00 310 B 9466-5K 11/18

Claims (5)

[Claims] 1. A wireless communication system comprising a relay station having a data relay function and other communication terminals, wherein the relay station has an identification means for identifying the type of a packet received from the communication terminal, When the received packet is a broadcast packet, a sending means for sending the broadcast packet to a wireless line is provided. 2. The wireless communication system according to claim 1, wherein the identifying means identifies whether the packet received from the communication terminal is a broadcast request packet using a control channel. 3. The transmission means uses a frequency hopping method as a radio channel.
The described wireless communication system. 4. The transmitting means transmits by a direct spread method of spread spectrum communication.
The described wireless communication system. 5. A wireless communication system composed of a plurality of communication terminals including a communication terminal having a relay function, wherein the type of packet received from a transmitting communication terminal is identified, and the identification result is a broadcast packet. In this case, the wireless communication system is characterized by including the steps of relaying and transmitting the broadcast packet to the communication terminal of the broadcast destination by wireless communication.