JP2715742B2 - Wireless local area network - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless LAN using the CSMA / CD system.

[0002]

2. Description of the Related Art In recent years, with the spread of portable and portable computers, portable wireless terminals, and the like, mobility of terminals connected to a LAN has become a problem, and realization of a wireless LAN has been demanded. Conventionally, this type of apparatus has been disclosed in
There is one disclosed in Japanese Patent No. 33941. FIG. 4 is a block diagram of a conventional CSMA / CD bus LAN shown in the above document. In the figure, 3 is a LAN medium such as a coaxial cable, 4 is a terminator, 5 is a terminal, 24 is a satellite, and 25 is a terminal.

Next, the operation will be described. A signal from the terminal 5 is converted into light or a radio wave by the photoelectric conversion element via the terminal 25 and transmitted to the space. Satellite 24
Then, light or radio waves transmitted through the terminal 25 are received, converted into a signal by a photoelectric conversion element, and transmitted to the LAN medium 3. Further, the signal from the LAN medium 3 is converted into light or radio wave by the photoelectric conversion element and transmitted to the space. On the other hand, the terminal 25 receives a signal from the satellite 24, converts the signal into a signal by a photoelectric conversion element, and sends the signal to the terminal 5. In the above satellite 24, when transmitting a signal from the terminal 25 to the LAN medium 3,
By comparing the signal transmitted to the LAN medium 3 with the signal folded back from the LAN medium 3, it is possible to detect a collision of signals generated when a plurality of satellites 24 transmit signals onto the LAN medium 3 at the same time. If a signal collision is detected, a collision signal is transmitted to the terminal 25. The terminal 25 receives the collision signal, and notifies the terminal 5 of the occurrence of the signal collision.
Inform If no signal collision is detected, the above-mentioned folded signal is transmitted to the terminal 25. Further, at terminal 25, a source transmission signal from terminal 5;
The signal collision is detected by comparing the signal returned by the LAN medium 3 with the signal.

[0004]

In the conventional example, since the above configuration is adopted, all signals from the terminals are transmitted to the LAN.
The data is transmitted to the destination terminal via the medium. for that reason,
While a signal is transmitted between a certain terminal via the LAN, the LAN medium is occupied by the terminal, and the other terminal is used until the communication of the terminal using the LAN ends and the LAN is released. Is in a standby state. Therefore, LAN
As the number of terminals connected to the LAN increases, the use of LAN media increases, the waiting time for signal transmission increases, and the throughput of LAN data transmission decreases. Also,
In the conventional example, the satellite 24 is used as a signal collision detection means,
In addition to the terminal 25, it is necessary to detect a collision signal transmitted from the satellite 24 to the terminal 25 to inform the terminal 25, and there is a problem that the circuit configuration becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. Even if the number of terminals connected to the LAN increases, the waiting time for signal transmission does not increase, and the throughput of LAN data transmission is reduced. It is an object of the present invention to obtain a wireless LAN to be prevented and to obtain a wireless LAN with a simplified device scale by integrating signal collision detection means.

[0006]

In order to achieve the above object, in a wireless LAN according to the first aspect of the present invention, L
A network-side transmission device that is an AN station;
Both of the terminal-side transmission devices connected to the terminal are provided with wireless transmission means, and the terminal-side transmission device connected to the terminal that sends the signal and the terminal-side transmission device connected to the terminal to which the signal is sent, etc. If the positions are within an area where stable wireless transmission is possible, the terminal-side transmission device connected to the terminal that sends the signal, the network-side transmission device, and the LAN
Medium, other network-side transmission devices, regardless of the transmission path consisting of the terminal-side transmission device connected to the terminal of the signal destination, as described above, so that the signal is transmitted via the wireless transmission path between the two terminal-side transmission devices, It is composed. A wireless LAN according to a second aspect of the present invention is the wireless LAN according to the first aspect, further comprising a network-side transmission device having the following elements and a terminal-side transmission device. (A) A terminal-side transmission device having the following elements: (a1) A signal from a terminal is transmitted to a CSMA / CD LAN.
A transceiver that converts the signal into a signal and sends it to the spread spectrum modulator, or converts a CSMA / CD LAN signal output from the spread spectrum demodulator into a signal that can be transmitted to the terminal and sends the signal to the terminal; (A3) spread-spectrum demodulating a received signal using a despreading code predetermined for this terminal-side transmission device,
A spread spectrum demodulation unit for transmitting the output to the transceiver unit; (a4) signal collision detection means for monitoring signal collision on a LAN medium and signal collision during wireless transmission; and (b) the following elements: (B1) a spread-spectrum demodulation unit that performs spread-spectrum demodulation on a signal wirelessly transmitted from the terminal-side transmission device by using a despreading code predetermined for the network-side transmission device; Network to send on LAN media
Over click transmission unit, (b2) receiving the signal on the LAN medium, using the address of the destination of the signal, the spread spectrum modulator for spread spectrum modulation.

[0007]

The wireless LAN of the present invention configured as described above
Then, a terminal-side transmission device connected to a terminal that sends a signal,
If the positions of the terminal-side transmission devices connected to the terminal or the like to which the signal is sent are within an area where stable wireless transmission is possible, the signal transmission directly from the terminal-side transmission device connected to the terminal that sends the signal. By transmitting a signal on the wireless transmission path to the terminal-side transmission device connected to the destination terminal, etc.,
Even if the number of terminals connected to the LAN increases, the waiting time for signal transmission does not increase, and it is possible to prevent a decrease in the throughput of LAN data transmission. In addition, the LAN medium and the wireless transmission path
Assuming that it is equivalent to a LAN medium in a wired LAN, LA
By providing the means for detecting a collision between N media and a signal at the time of wireless transmission only in the terminal-side transmission device, the device scale can be simplified.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a CSMA / C showing Embodiment 1 of the present invention.
FIG. 1 is a block diagram of a wireless LAN using the D method. In the figure, 1 is a network-side transmission device, 2 is a terminal-side transmission device, and 3 to 5 are the same as those in the conventional example, and the description is omitted.

FIG. 2 is an internal configuration diagram of the terminal-side transmission device 2 of FIG. Reference numeral 6 denotes a CSMA / CD type transceiver unit. The transceiver unit 6 receives a signal from the terminal CS
Means for converting the signal into a LAN signal of the MA / CD system and sending it to the spread spectrum modulation section 9;
And a means for converting a CSMA / CD LAN signal from the terminal into a signal that can be transmitted to the terminal 5. Further, the transceiver unit 6 has means for comparing a signal from the terminal with a signal looped back by the medium 3 and another terminal-side transmission device 2 or the network-side transmission device 1 to detect a signal collision. .

Reference numeral 7 denotes a CSMA /
An address detector for detecting an address of a destination of a signal converted from a signal from the terminal from a CD; a spread-spectrum code generator for generating a predetermined spread-spectrum code based on the address detected by the address detector; , 9 is a spread spectrum modulator for spreading and modulating the signal from the terminal using the above spread spectrum code, 10 is an amplifier for amplifying the signal spread and modulated by the spread spectrum modulator 9, and 11 is an antenna for transmission and reception. Antenna duplexer for 12 is an amplifying unit for amplifying the received signal,
Reference numeral 13 denotes a spread spectrum demodulation unit that performs spread spectrum demodulation of a received signal using a despreading code predetermined for the terminal-side transmission device, and sends the demodulated signal to the transceiver unit 6. Reference numeral 14 denotes a transmitting / receiving antenna, which is located in the wireless service area of the network-side transmission device and is used for transmission / reception with the network-side transmission device, or has another position in an area where stable wireless transmission is possible. It is for transmission and reception with the terminal side transmission device.

Next, FIG. 3 is an internal configuration diagram of the network side transmission device 1 of FIG. In the figure, reference numeral 15 denotes a network receiving unit for receiving a signal on the LAN medium 3, 16 denotes an address detecting unit for detecting a destination address of a signal on the LAN medium 3 received by the network receiving unit 15, and 17 denotes an address detecting unit 16. A spread code generator 18 for generating a predetermined spread code for the detected address; a spread spectrum modulator 18 for spread spectrum modulating the signal received from the LAN medium by the network receiver 15 using the spread code; Is an amplifying unit for amplifying the signal subjected to spread spectrum modulation by the spread spectrum modulation unit 18, and 20 is an antenna duplexer for sharing an antenna for transmission and reception. Reference numeral 21 denotes an amplifying unit for amplifying a signal wirelessly transmitted from the terminal-side transmission device, and reference numeral 22 denotes a spectrum for spread-spectrum demodulating a signal from the terminal-side transmission device using a despreading code predetermined for the network-side transmission device. Spread demodulation unit, 23
Is a network transmission unit for transmitting the signal subjected to the spread spectrum demodulation to the LAN medium 3.

The operation of the wireless LAN having the above configuration will be described. First, an operation of wirelessly transmitting a signal from the terminal 5 directly to the terminal-side transmission device 2 connected to the destination terminal or directly to the network-side transmission device 1 via the transmission-side terminal-side transmission device 2 Will be described. The signal from the terminal 5 is input to the terminal-side transmission device 2 on the transmission side. The signal from the terminal 5 input to the terminal-side transmission device 2 is converted into a CSMA / CD signal by the transceiver unit 6. From this signal, the address of the destination of the signal is detected by the address detection unit 7. If the positions of the terminal-side transmission device 2 connected to the terminal 5 to which the signal is sent and the terminal-side transmission device 2 on the transmission side are within an area where stable wireless transmission is possible, the spreading code generation unit 8 Destination terminal 5
A predetermined spreading code is generated in the terminal-side transmission device 2 connected to. On the other hand, if the positions of the terminal-side transmission device 2 connected to the terminal to which the signal is sent and the terminal-side transmission device 2 on the transmission side are not within the above-described area, the terminal-side transmission device 2 on the transmission side Generates a predetermined spreading code in the network-side transmission device 1 whose location is within the wireless service area. Using the spread code generated by the spread code generator 8, the signal input from the terminal 5 and converted into a CSMA / CD system LAN signal by the transceiver 6 is spread spectrum modulated and amplified by the amplifier 10. ,
The signal is transmitted from the antenna 14 via the antenna sharing device 11.

Next, the network side transmission device 1 converts the signal wirelessly transmitted from the transmission side terminal side transmission device 2 to the LAN.
The operation of transmitting the signal on the medium 3 and receiving the signal on the LAN medium 3 and wirelessly transmitting the signal to the terminal-side transmission device 2 connected to the destination terminal of the signal will be described. The network-side transmission device 1 receives a signal from the transmission-side terminal-side transmission device 2 and amplifies the signal with an amplifier 21. To perform spread spectrum demodulation by using the multiple access of the spread spectrum communication to receive only the signal transmitted to the network side transmission apparatus 1. Then, the above-mentioned received signal is transmitted from the network transmission unit 23 to the LAN medium 3. When the signal is transmitted on the LAN medium 3,
The network receiving unit 15 receives the signal transmitted on the LAN medium 3 and transmits the signal (the signal folded back on the LAN medium 3) to the transmitting-side terminal transmission device 2 by the spread spectrum modulation unit 18. Spread spectrum modulation is performed using a predetermined spreading code, amplified by an amplifier 19, wirelessly transmitted from an antenna 14 via an antenna duplexer 20,
It is used for detecting collision of a signal on the LAN medium 3 in the terminal-side transmission device 2 on the transmission side.

When the network-side transmission device 1 does not receive a signal from the terminal-side transmission device 2 on the transmission side, the network reception unit 15 receives a signal on the LAN medium 3 and sends the signal to the address detection unit 16. To detect the address of the terminal to which the signal is sent, and if the terminal side transmission device 2 connected to the signal destination terminal is within the wireless service area of the network side transmission device 1, the spreading code generation unit At 17, using a predetermined spreading code in the terminal-side transmission device 2 connected to the terminal of the signal destination,
The received signal on the LAN medium 3 is spread-spectrum-modulated by the spread-spectrum modulator 18, amplified by the amplifier 19, and transmitted from the antenna 14 via the antenna duplexer 20. If the terminal-side transmission device 2 connected to the terminal to which the signal is sent is not within the wireless service area of the network-side transmission device 1, the network-side transmission device 1 generates a spread code or generates a spread spectrum signal. No modulation or transmission is performed.

Next, the operation in which the terminal side transmission device 2 receives a signal from the network side transmission device 1 or another terminal side transmission device 2 and sends it to the destination terminal 5 and the operation of detecting signal collision Will be described. When the terminal-side transmission device 2 is within the wireless service area of the network-side transmission device 1 or when the position of another terminal-side transmission device 2 is within an area where mutually stable wireless transmission is possible, , And converts the signal to an amplifier 12
, And spread-spectrum demodulation unit 13 performs spread-spectrum demodulation on the terminal-side transmission device 2 using a predetermined despreading code.
And demodulates the signal transmitted to. Then, the received signal is transmitted to the transceiver unit 6. The signal transmitted to the transceiver unit 6 is converted from the CSMA / CD format to a signal that can be transmitted to the terminal 5 and transmitted to the terminal 5.

When the input signal of the transceiver section 6 is a signal transmitted from another terminal side transmission device 2 in particular, the signal is again spread-modulated using a spreading code predetermined for the terminal side transmission device 2. Then, the signal is looped back and transmitted to the terminal-side transmission device 2 on the transmission side for collision detection during wireless transmission.

In the transceiver unit 6, when a signal from the terminal 5 is wirelessly transmitted to another terminal-side transmission device 2 or the network-side transmission device 1, a source signal from the terminal 5 and another terminal The signal collision is monitored by comparing the signals looped back by the transmission device 2 on the side and the transmission device 1 on the network side. When a signal collision occurs, the folded signal and the source signal are different irrespective of the position where the collision occurs on the LAN medium or on the network side transmission device during wireless transmission. Can be detected. In the present invention, since the signal collision detecting means is provided only in the transceiver unit 6 of the terminal-side transmission device 2, radio transmission of the collision signal is eliminated as in the case of the conventional example. There is an advantage that a collision detection error due to a transmission error can be prevented.

In the above embodiment, the terminal-side transmission device 2 having the radio transmission / reception means connected to the terminal 5 having no radio transmission / reception means is described as an example. However, the present invention is not limited to this. An integrated structure having the function of the terminal-side transmission device described above is also equivalent.

In the above embodiment, a coaxial cable or a twisted pair cable has been described as an example of the LAN medium 3. However, it is needless to say that the present invention can be realized with an optical cable.
In the above embodiment, the address detection unit 7 detects the destination address of the signal from the signal obtained by converting the signal from the terminal into the CSMA / CD signal by the transceiver unit 6. It is needless to say that the present invention can be realized even if the address of the destination is detected. In the above embodiment, the antenna duplexers 11 and 20 are used.
Although the example in which the transmission / reception antenna 14 is shared has been described by using the above, it is needless to say that the present invention can be realized even when separate antennas are used for transmission / reception without using the antenna sharing device. In the above embodiment, the spread spectrum communication system is used for wireless transmission, and the spread code generators 8 and 17 of each device generate a spread code unique to the destination of the signal, thereby realizing the multiple access function. However, the spread code generators 8 and 17 are frequency synthesizers, and the spread spectrum modulators 9 and 18 are used as modulators of other modulation schemes.
The multiple access function is realized by replacing the spread spectrum demodulation units 3 and 22 with demodulation units of other modulation methods, and using a modulation method other than the spread spectrum communication method for radio transmission and assigning different frequencies to each device. Needless to say, the present invention can be realized even in such a case.

[0020]

Since the present invention is configured as described above, it has the following effects.

If the terminal-side transmission device for wirelessly transmitting a signal from the terminal and the terminal-side transmission device connected to the terminal to which the signal is sent are located within an area where mutually stable wireless transmission is possible, The wireless transmission from the terminal-side transmission device connected to the terminal sending the signal directly to the terminal-side transmission device connected to the terminal to which the signal is sent without passing through the network-side transmission device of the LAN station and the LAN medium, With such a configuration, it is possible to obtain a wireless LAN that prevents a decrease in the data transmission throughput of the LAN even when the number of terminals connected to the LAN increases.

The LAN medium and the wireless transmission path are connected by a wired L
By providing a means for detecting a signal collision on the LAN medium and only in the terminal-side transmission device on the assumption that the LAN medium is equivalent to the LAN medium in the AN, a wireless LAN with a simplified device scale can be obtained.

[0023] Within the wireless service area of each network-side transmission device, it is possible to obtain a wireless LAN in which terminals can be easily moved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a wireless LAN showing a first embodiment of the present invention.

FIG. 2 is an internal configuration diagram of the terminal-side transmission device of FIG. 1;

FIG. 3 is an internal configuration diagram of the network-side transmission device of FIG. 1;

FIG. 4 is a block diagram of a wireless LAN showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Network side transmission apparatus 2 Terminal side transmission apparatus 3 LAN medium 4 Terminator 5 Terminal 6 Transceiver part 7 Address detection part 8 Spread code generation part 9 Spread spectrum modulation part 10 Amplification part 11 Antenna duplexer 12 Amplification part 13 Spread spectrum demodulation part 14 Antenna 15 Network Receiver 16 Address Detector 17 Spread Code Generator 18 Spread Spectrum Modulator 19 Amplifier 20 Antenna Duplexer 21 Amplifier 22 Spread Spectrum Demodulator 23 Network Transmitter

Claims (2)

(57) [Claims] A wireless local area network (hereinafter referred to as a local area network) using the CSMA / CD system.
A network is abbreviated as a LAN). Both the network-side transmission device, which is a station of the LAN, and the terminal-side transmission device connected to the terminal are provided with wireless transmission means, and the terminal side connected to the terminal that sends a signal. If the transmission device and the terminal-side transmission device connected to the terminal to which the signal is sent are located within an area where stable wireless transmission is possible, the terminal-side transmission connected to the terminal that sends the above signal Regardless of the transmission path consisting of the network-side transmission device that is a LAN station, the LAN medium, another network-side transmission device, and the terminal-side transmission device connected to the terminal to which the signal is sent, the above-mentioned two-terminal-side transmission A wireless LAN configured to transmit signals via a wireless transmission path between devices. 2. The wireless LAN according to claim 1, comprising: a network-side transmission device having the following elements; and a terminal-side transmission device. (A) A terminal-side transmission device having the following elements: (A1) A signal from a terminal is transmitted to a CSMA / CD LAN.
A transceiver that converts the signal into a signal and sends it to the spread spectrum modulator, or converts a CSMA / CD system LAN signal output from the spread spectrum demodulator into a signal that can be transmitted to the terminal and sends it to the terminal; (A3) spread-spectrum demodulating a received signal using a despreading code predetermined for this terminal-side transmission device,
A spread spectrum demodulation unit for transmitting the output to the transceiver unit; (a4) signal collision detection means for monitoring signal collision on a LAN medium and signal collision during wireless transmission; and (b) the following elements: (B1) a spread-spectrum demodulation unit that performs spread-spectrum demodulation on a signal wirelessly transmitted from the terminal-side transmission device by using a despreading code predetermined for the network-side transmission device; Network to send on LAN media
Over click transmission unit, (b2) receiving the signal on the LAN medium, using the address of the destination of the signal, the spread spectrum modulator for spread spectrum modulation.