JPH04287445A - Radio terminal equipment for lan system - Google Patents

Abstract

PURPOSE:To improve the mobility, to enhance the stability of a terminal equipment and the miniaturization and to facilitate the installation and revision of the system by devising it that the same data as its own transmission data is not received and eliminating the need for a cable for the LAN. CONSTITUTION:A radio repeater to implement control of radio communication is connected between radio terminal equipments each provided with a radio equipment in compliance with the CSMA/CD system and a switch selecting an operating radio channel is provided to the radio terminal equipment and the radio repeater. Moreover, the radio terminal equipment consists of a radio MODEM section 15 implementing radio control and a terminal equipment 11 implementing data processing and the radio MODEM section 15 is provided with a collision detection circuit 159 monitoring whether or not data from other station is received during the transmission from its own station, comparing an input signal of a limiter/low pass filter 151 with the output of a low frequency amplifier circuit 158 upon the receipt of the data to detect thereby reporting a collision signal CD to a LAN interface control section 116.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to CSMA/CD (Carrier Sense) in a LAN system.
Multiple Access with
The present invention relates to a terminal device that can control wireless communication using a Collision Detection method.

0002

2. Description of the Related Art LAN systems are being adopted in various fields, and their types and scales are becoming more diverse and expanding. A LAN terminal using the CSMA/CD system, which is the most widely used, detects whether or not data is flowing on the network, and starts data transmission if there is free space. If two terminals start transmitting at the same time, the transmitted data will be received by the own terminal, and the data will be distinguished from the other transmitted data depending on whether or not it receives data different from the transmitted data. Check for collisions. When a collision is detected, the data is retransmitted after waiting for a certain amount of time. LAN systems are categorized by connection type: (a) bus-type LAN, in which multiple terminals are directly connected to a single linear cable, or multiple terminals are connected via repeaters; (b) joining the cables in a closed loop;
A ring-type LAN that connects multiple terminals to the ring, and (c
) There is a star type LAN in which a control device is placed at the center, cables are extended from there in a star shape, and terminal devices are connected via a HUB or a repeater. Attempts have been made to use wireless in these LAN systems.

[0003] On the other hand, for example, in conventional radio equipment specified in the standard ``Specified Low Power Radio Station, Radio Equipment for 400MHz Band Data Transmission'' published by the Radio System Development Center, the carrier Sensing was carried out, but collision monitoring during transmission and retransmission processing due to collisions were not performed. The above wireless device has a data terminal device with a 400M
It is connected to wireless equipment for Hz band data transmission. This radio equipment is comprised of a transmitting device, a receiving device, and a control device that controls them, and this control device is provided with a calling name storage device, a transmission time limit device, and a carrier sense device. The functions of this radio equipment are (a)
(b) Basic type M-to-N multiple radio equipment placed in the same location and controlled by one data terminal. (c) For the purpose of expanding the service area, relay stations are placed and base stations are established using two or four frequencies. 1-to-1 or 1-to-N area expansion type that performs simplex or duplex communication between stations and slave stations, between slave stations, and (d) Area expansion type M pair that installs multiple radio equipment in a distributed manner. There are N distributed base types.

0004

[Problem to be Solved by the Invention] In a repeater that controls a plurality of wireless terminal devices and transfers data within a LAN system composed of conventional coaxial cables, it is necessary to When several repeaters are connected and multiple repeaters transfer data on the same wireless channel band, the data transfer from each terminal is received by two repeaters at the same time and the coaxial Because the data is transferred over the cable, each repeater receives the same data as its own data sent from the other repeater, and determines that a transmission/reception conflict has occurred. It will move to collision detection state. When this state occurs, transmission from the terminal becomes impossible. In addition, the interface between the wireless modem and the terminal being considered for broadband networks is based on RS232, for example, and consists of a transmitting data line and a receiving data line, so collisions can occur. Detection signal is not defined. Therefore, it is necessary to control communication using a higher-level protocol to prevent collisions from occurring during wireless communication. However, with this, communication between N terminals and N terminals was impossible.

The first object of the present invention is to solve one of the conventional problems, and to create a LAN system that prevents data from being received as the same as its own transmitted data and prevents contention from occurring. An object of the present invention is to provide a wireless terminal device. A second object of the present invention is to solve other conventional problems and provide a wireless terminal device for a LAN system that can detect and retransmit when a conflict occurs in wireless communication. It is about providing.

[0006]

[Means for Solving the Problems] In order to achieve the above object, a wireless terminal device for a LAN system according to the present invention has the following features: (a) connecting a plurality of terminals to one cable directly or via a repeater; CSMA/ A wireless terminal device equipped with a wireless device that complies with the CD system is connected to a wireless repeater that controls wireless communication between the wireless terminal device and the wireless terminal device and the wireless repeater. It is characterized by the provision of a switch to change the channel band. (b) A wireless terminal device is composed of a wireless modem section that performs wireless control and a terminal device that performs data processing. A collision detection circuit is provided which monitors whether data has been received and detects a collision when data is received, and when the collision detection circuit detects a collision, it reports it to the terminal device via the interface. It also has its own characteristics.

[0007]

[Operation] In the present invention, (a) a switch is provided to set the wireless channel used for each repeater, and when each repeater is installed in each section or floor of an office, When performing data communications, different frequencies are used by switching switches for each section or floor, and a radio frequency band is assigned to a designated radio channel for communication. Since each repeater uses a different radio frequency band, there will be no crosstalk even if the repeaters are installed close to each other. Further, since each terminal device pairs the radio frequency band used with each repeater, there is no possibility of crosstalk. (b) If a transmission/reception conflict is detected on the wireless modem,
The collision detection signal is reported to the data communication section of the terminal device. On the terminal device side, when a collision detection state is reported, the transmission operation is temporarily interrupted, and the retransmission data is retransmitted after a certain period of time. In this manner, by reporting the collision detection state to the terminal device, the terminal device side can perform data transfer using the CSMA/CD method, and as a result, data transfer can be performed normally.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings. FIG. 2 is a connection configuration diagram of a LAN system using CSMA/CD type wireless terminals to which the present invention is applied. In FIG. 2, 11 is IEEE (The Ins
Titute of Electrical a
nd Electronics Engineers)
802.3 10BASE5 (CSMA/CD bus type LAN standard) terminal device, 12 is IEEE802
．． 3 for 10BASET (CSMA/CD system star)
type LAN standard) terminal device, 13 is a C type terminal device adopting the present invention.
SMA/CD wireless terminal, 14 is 10BASET (
A wireless modem 15 is connected to the terminal device 12 (star type LAN standard), 15 is for 10BASE5 (bus type LAN standard)
21 is a 10BASE5 repeater that connects a conventional 10BASET terminal to a 10BASE5 coaxial cable 31, 22,2
3 is a wireless repeater that connects a CSMA/CD wireless terminal to a 10BASE5 coaxial cable 31; 30 is a transceiver (transmitter/receiver) connected to the coaxial cable 31;
It is. Note that although the wireless repeaters 22 and 23 are connected to the coaxial cable 31 in FIG.
It is also possible to control the wireless terminal independently without connecting to 1. In FIG. 2, five types of terminals are connected to a coaxial cable 31 to form one LAN system. The two terminals 11 on the right are CSMA/CD type conventional bus type LAN terminal devices, and the next terminal 12 is a transceiver.
The next terminal 13 is connected to the transceiver 30 of the coaxial cable 31 via the wireless repeater 22 in accordance with the present invention.
is a wireless terminal device connected to the next terminal 12, 11.
On the right side is the star terminal 12 connected to the wireless modem 14.
The left side is a bus type terminal 11 connected to a wireless modem 15. That is, in FIG. 2, the bus type terminal has A,
Star-type terminals are given the symbol B, and wireless terminals are given the symbol C. For example, when communicating between the terminal 11 connected to the wireless modem 15 on the left and the terminal 12 connected to the third repeater 21 from the right, the signal from the terminal 11 is transmitted by the wireless modem 15. Convert to modulated wave and repeater 2
3 to the transceiver 30,
0, data is transferred in the left and right direction on the coaxial cable 31. When the third transceiver 30 from the right side receives this and detects that it is addressed to itself, it sends it to the repeater 21, and from the repeater 21 to each terminal 12, the third transceiver 30 from the right side receives the message. Terminal 12 detects its destination and receives it. In the present invention, these five types of terminals 11
, 12, and 13 are operated using the CSMA/CD method, and channels of different frequencies are switched and used for each floor, so there is no crosstalk or collision.

FIG. 3 is a minimum configuration diagram of a LAN system using CSMA/CD wireless terminals according to the present invention. The wireless terminal 13 is a system that performs transmission and reception in the same frequency band. Each wireless terminal 13 in FIG. 3 is a plurality of wireless terminals 13 wirelessly connected to the wireless repeater 22 in FIG. When communicating with terminals 11 and 12 other than the wireless terminal 13 in the LAN system, the wireless terminal 13 uses a wireless repeater 22, a transceiver 30, a coaxial cable 31, a wireless repeater 21, or a conventional Communication is performed after being connected to another terminal via the repeater 21 or directly. However, when the wireless terminals 13 communicate with each other, they can communicate directly without going through the wireless repeater 22. In this way, when communicating between each wireless terminal in the minimum LAN system of FIG. 3, or when mutual communication is performed through only one wireless repeater 22 of FIG.
If data is not transferred to the cable 31, there will be no collision or interference, and no particular problem will occur. However, when a plurality of repeaters 22 and 23 are connected to the coaxial cable 31 and communicate in the same radio frequency band, interference and collision occur, which poses a problem. For example, data transmitted from one CSMA/CD type wireless terminal 13 is sent to the wireless repeater 2.
2 and 23, it is converted into a 10BASE5 signal, and if there is no data (carrier) from another terminal on the coaxial cable 31, transmission is started. wireless repeater 22,
When the transceiver 30 to which the transceiver 23 is connected starts transmitting, it monitors whether a collision occurs on the coaxial cable 31. When communication is performed in the same frequency band, the wireless repeaters 22 and 23 start data transmission at the same time, so data collision is sure to occur. This collision information is reported to the CSMA/CD wireless terminal 13, and data transfer is interrupted. Since this operation occurs every time data is transferred, transmission from the wireless terminal 13 becomes impossible. Therefore, in order to avoid this problem, in the present invention, the radio repeaters 22 and 23 are provided with a plurality of radio frequency bands, and the selection can be made using a manual switch. The wireless terminal 13 similarly has a plurality of radio frequency bands, and by inputting the area or organization where the repeater is installed, the usable radio frequency band is set. By changing the radio frequency band used by each radio repeater, the number of repeaters that perform data communication with one radio terminal 13 is limited to one, and the problem of collision does not occur.

FIG. 1 is a connection configuration diagram of a wireless modem and a terminal device showing one embodiment of the present invention. Here, the connection between the wireless modem 15 and the bus terminal device 11 shown in FIG. 2 is shown. The IEEE802.3 10BASE5 terminal device 11 includes a processing device 111 and a memory 1 equipped with a 10BASE5 protocol control/application program.
12, FD (flexible disk) control unit 113, flat panel display control unit 114, 10BAS
The LAN control unit 115 of the E5 and the LAN interface
The control section 116 consists of a control section 116. Also, wireless modem 1
5 is a limiter/low-pass filter 15 as a transmission system.
1. Oscillation circuit 152, limiter/low-pass filter 15
A mixing circuit 153 that modulates the output of 1 to a high frequency with the output of an oscillation circuit 152, and a voltage/power amplification circuit 154 are arranged.
The receiving system includes a demodulation circuit 157 that detects and demodulates the amplified received data from the power voltage amplification circuit 155 based on the output from the oscillation circuit 156, and a low frequency amplification circuit 158.
is located. Here, the circuit of the present invention is different from the conventional circuit by comparing the input signal of the limiter/low-pass filter 151 and the output of the low-frequency amplification circuit 158 and detecting a mismatch. A collision detection circuit 159 that reports to the speed control unit 116 is provided. A collision detection circuit 159 compares the transmitted data and the received data, and detects that a collision has occurred if a mismatch of more than a certain percentage occurs. Then, this is reported to the LAN interface control section 116 on the terminal side by sending a collision signal (CD) via the collision display line 41. The connection between the wireless modem 15 and the terminal device 11 is made by a transmission line 40, a reception line 42, and a collision display line 41, which are signal lines compliant with the IEEE 802.5 standard.

FIG. 4 is a diagram showing the format of data flowing on the LAN system. When transmitting data from the terminal device 11, processing is performed as follows. Processing device 1
11 and the program on the memory 112 to prepare the transmission data on the memory 112. After preparing the transmission data, L
When the AN control unit 115 is activated, the LAN control unit 11
5 checks the reception line 42 at regular intervals, determines that no carrier is being received, and stores the transmission data in the memory 112.
The data is set to the IEEE802.5 format as shown in FIG. 4, and the transfer is started. The format is 6 octets of destination address (DA), 6 octets of source address (SA), and 48 to 1502 octets of data.
DATA and 4 octet frame check sheet
It is formed from cans (FCS). During transmission, the collision detection signal 41 is monitored, and if the collision detection signal 41 is not set by the end of transmission, it is assumed that the transmission was successful. If the collision detection signal 41 is set during transmission, it is assumed that a data collision has occurred on the LAN system, and the transmission is interrupted, a jam pattern is transmitted, and the transmission is forcibly terminated. If a collision occurs, data is transmitted again at regular intervals. Next, the reception operation will be explained. When the LAN control unit 115 starts receiving, it monitors the receiving line 42 and if it determines that the received data is addressed to its own station, it starts the receiving operation and stores the received data on the memory 112. Transfer. When the end of the received data is detected, it is determined whether the jam pattern described above has occurred and whether the FCS is normal or not, and the reception operation is ended.

0012

[Effects of the Invention] As explained above, according to the present invention,
Since LAN terminals that were conventionally connected only by wires can now be connected wirelessly, there is no need to connect cables to the terminals themselves, improving the mobility of the device. Further, since there is no need to consider the stability of the terminal, which would be a problem when connected to a thick cable such as a coaxial cable, it is possible to downsize the device. Furthermore, since the cables of the LAN system are eliminated, the system can be installed and changed freely.

[0013]

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration and connection of a wireless modem and a terminal device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a large-scale LAN system using CSMA/CD wireless terminals according to the present invention.

FIG. 3 is a layout diagram of a minimum scale LAN system using CSMA/CD type wireless terminals according to the present invention.

FIG. 4 is a format diagram of data flowing on a LAN system.

[Explanation of symbols]

11 10BASE5 terminal 12 10BASET terminal 13 Wireless terminals 14, 15 Wireless modems 22, 23 Wireless repeater 30 Transceiver 31 Coaxial cable 40 Transmission line 41 Collision detection display line 42 Reception line 111 Processing unit (CPU) 112 Memory 113 FD control section 114 Display 115 LAN controller 116 LAN interface control section 151 Limiter/low-pass filter 152, 156 Oscillator circuit 153 Mixer 154, 155, 158 Amplifier 157 Demodulation circuit

Claims (2)

[Claims] Claim 1: A bus type LAN in which multiple terminals are connected to one cable directly or via a repeater, a control device is placed in the center, and cables are extended in a star shape from there, In a star LAN system that connects multiple terminal devices via a HUB or repeater, CSMA/
a wireless terminal device equipped with a wireless device compliant with the CD system;
A wireless repeater for controlling wireless communication with the wireless terminal device is connected, and the wireless terminal device and the wireless repeater are provided with a switch for switching a wireless channel band to be used. Wireless terminal device for LAN system. 2. The wireless terminal device for a LAN system according to claim 1, wherein the wireless terminal device comprises a wireless modem section that performs wireless control and a terminal device that performs data processing, and the wireless modem section is equipped with a collision detection circuit that monitors whether or not data is received from another station while transmitting from the own station, and detects a collision when the data is received. A wireless terminal device for a LAN system, characterized in that when a collision is detected, it is reported to the terminal device via an interface.