JPH11331175A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable satisfactory transmission/reception at all times while preventing the reduction of communication ability corresponding to the change of a transmission/reception environment. SOLUTION: The ID data of a counter terminal are detected from a received signal by a counter side terminal ID extracting circuit 6, the reception level of the received signal is detected by a reception level detector 5, control data for correcting reference packet length data are outputted from a control data output circuit 7 based on that reception level, packet length data stored in a packet length data memory 8 are corrected based on the control data, the packet length data are read out of the packet length data memory 8 by a packet length setting circuit 10 at the time of transmission, the transmission is performed based on the corrected packet length data corresponding to the ID of the counter side terminal, and data can always be transmitted in a state of high communication capability, while reducing the disappearance of packets due to errors with the optimum packet length which corresponds to the state of received radio waves.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication system in which a plurality of wireless communication terminals mutually transmit data via a wireless channel within a predetermined service area.

[0002]

2. Description of the Related Art A LAN (Local Area N) having a service area of a radius of several tens to several hundreds of meters installed in the same building or premises of an office or an office building, mainly for computer communication.
In the network, a coaxial cable, a twisted pair cable, or the like is installed in a service area as a transmission medium. In this conventional LAN, there is a problem that if the layout is changed from the initial installation state, re-installation work requires a great deal of time and installation cost.

[0003]

In order to solve this problem, a wireless LAN has been used in which wiring work at the time of introduction is simple and layout after installation is easily performed. It is known that the communication capability of the wireless LAN depends on the transmission packet length and the error rate depending on the radio wave reception state in the transmission environment. In the current wireless LAN,
Since the transmission packet length is determined on the premise of communication in a transmission / reception environment in which radio wave transmission / reception conditions are good, for example, a room in which a wireless communication terminal is placed is redesigned, and a large book shelf becomes wireless. Placed near communication terminals,
Due to a change in the transmission / reception environment in which a large number of people are gathering and having a meeting, the transmission / reception state is deteriorated, the communication capability is reduced, and normal communication may not be possible.

[0004] The present invention has been made in view of the current state of operation of a wireless LAN as described above, and has as its object to prevent a decrease in communication capability in response to a change in a transmission / reception environment.
An object of the present invention is to provide a wireless communication system capable of always performing good transmission and reception.

[0005]

According to one aspect of the present invention, there is provided a wireless communication system in which a plurality of wireless communication terminals mutually transmit data via a wireless channel within a predetermined service area. ID detection means for detecting the ID data of the other terminal from the reception signal, level detection means for detecting the reception level of the reception signal, and the packet length in which the ID data of the other terminal and the corresponding packet length data are stored. A data storage unit, an adjustment data output unit that outputs correction data for correcting packet length data stored in the packet length data storage unit based on the reception level detected by the level detection unit; Correction means for correcting the packet length data stored in the packet length data storage means according to the adjustment data of Transmission control means for reading out the corrected packet length data corresponding to the ID of the partner terminal from the packet length data storage means and performing transmission based on the packet length data, provided in the wireless communication terminal. It is a feature.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing a configuration of the present embodiment, and FIG. 2 is a characteristic diagram showing a relationship between a communication capability and an error rate with respect to a packet length.

In the present embodiment, as shown in FIG. 1, an input terminal of a radio receiver 2 for receiving a reception signal at an antenna 1 and an output terminal of a radio transmitter 3 for outputting a transmission signal are:
The reception level detector 5 is connected to one output terminal of the radio receiver 2 and is connected to the reception level detector 5 for detecting the level of the reception signal. The other output terminal of the radio receiver 2 is connected to the other output terminal of the radio receiver 2. , A counterpart terminal ID extracting circuit 6 for extracting the ID of the counterpart terminal from the received signal. An output terminal of the reception level detector 5 is connected to an input terminal of an adjustment data output circuit 7 that outputs adjustment data for correcting packet length data.

The output terminal of the adjustment data output circuit 7 is connected to the first terminal of the packet length data storage 8 in which the packet length data is stored corresponding to the ID data of the other terminal.
, The output terminal of the other terminal ID extraction circuit 6 is connected to the second input terminal of the packet length data storage 8, and the output terminal of the packet length data storage 8 is connected to the transmission signal. The input terminal of the packet length setting circuit 10 is connected to one input terminal of the packet length setting circuit 10 for setting the packet length, and the output terminal of the packet length setting circuit 10 is connected to the input terminal of the wireless transmitter 3.

In this embodiment, a terminal device 13 such as a personal computer for outputting a transmission signal is provided, and an output terminal of the terminal device 13 is connected to a controller 12 for controlling transmission / reception and rewriting of packet length data. Then, a first control terminal of the controller 12 is connected to the wireless receiver 2, and a second control terminal of the controller 12 has a destination terminal ID extraction circuit 11 for extracting a destination terminal ID from a transmission signal.
And the other input terminal of the packet length setting circuit 10 are connected in parallel with each other.
The first output terminal is connected to the third input terminal of the packet length data storage 8.

The operation of the present embodiment having such a configuration will be described. In the present embodiment, the packet length data storage 8
In advance, a plurality of sets of addresses of a plurality of wireless communication terminals serving as counterpart terminals arranged in the service area and corresponding reference packet length data in a transmission / reception environment of a good reference are stored in advance. ing. The adjustment data output circuit 7 stores adjustment data for correcting the reference packet length data in accordance with the reception level. And
Under the control of the controller 12, the wireless receiver 2 monitors and detects the presence or absence of a carrier of a predetermined frequency in the received signal Fr from another wireless communication terminal except when the wireless transmitter 3 is transmitting.

In this state, the radio receiver 2 receives the received signal Fr.
Is received, the reception level detector 5 detects the reception level data fL of the reception signal, and the partner terminal ID extraction circuit 6 detects the ID data fI of the partner terminal. Then, the adjustment data output circuit 7 searches the stored data for adjustment data for correcting the reference packet length data in accordance with the input reception level data fL. 8, the corresponding adjustment data fm is input. Also,
The packet length data storage 8 receives the ID data fI of the partner terminal from the partner terminal ID extraction circuit 6.

Therefore, in the packet length data storage 8,
Reference packet length data corresponding to the ID data fI of the partner terminal input from the partner terminal ID extraction circuit 6 is corrected based on the adjustment data fm input from the adjustment data output circuit 7, and the corrected packet length The data is stored again in the packet length data storage 8.

The operation of adjusting the packet length data in the packet length data storage 8 in this case will be described with reference to the characteristic diagram of FIG. As shown in FIG. 2, there is a relationship such as a characteristic curve C1 between the communication capability and the error rate when communication is performed with a predetermined packet length.
When the communication is performed with the packet length shorter than the above, a relationship like the characteristic curve C2 is seen between the communication capability and the error rate. In the case shown in FIG. 2, when communication is performed in a favorable transmission / reception environment with a low error rate, the communication performance is improved as the packet length is longer, but in a transmission / reception environment where the error rate is higher than a predetermined error rate e0. When the communication is performed by using, the shorter the packet length, the higher the communication capability.

In this embodiment, the packet length at the time of communication in a favorable transmission / reception environment with a low error rate is initially stored in the packet length data storage 8 as reference packet length data. 5, the packet length data is adjusted as needed based on the error rate corresponding to the reception level detected, and when the error rate increases beyond a predetermined error rate e0, the packet length data is shortened.

In the present embodiment, the reception level is constantly monitored during the reception of the reception signal from the partner terminal, and the packet length data is adjusted and rewritten in the packet length data storage 8 as necessary. It is. When the reception of the reception signal from the partner terminal ends, the controller 12
Thus, the transmission mode fs is set, and the transmission data fs from the terminal device 13 is supplied by the controller 12 to the transmission destination terminal ID extraction circuit 11 and the packet length setting circuit 10.

In this state, the packet length data storage unit 8 stores the packet length data extracted by the destination terminal ID extracting circuit 11 and adjusted as necessary in accordance with the input destination terminal TD data. The searched packet length data fp is supplied from the packet length data storage 8 to the packet length setting circuit 10. The packet length setting circuit 10 forms a predetermined packet format for the transmission data fs supplied from the controller 12 based on the supplied packet length data fp.

In one example of this packet format, a packet start flag, a destination terminal address, a source address, a type and control method of a bucket, a packet sequence number, transmission data, parity check data, and a packet end flag are provided. A packet of one frame is formed,
The maximum length of one frame is approximately 2 Kbytes, and the transmission speed is approximately 2 Mbit / sec. Transmission data configured in such a packet format is input to the wireless transmitter 3 and modulated, and transmitted from the wireless transmitter 3 as a transmission signal Fs via the antenna 1. The transmission signal Fs in this case
Is corrected to an optimum value based on the signal level of the received signal Fr from the partner terminal in advance.
Transmission / reception with the partner terminal is performed in the maximum communication capacity state according to the transmission / reception environment at that time.

For example, when a large number of conference attendees are present in the room where the partner wireless communication terminal is located, the level of the signal received from the partner wireless communication terminal is reduced and stored in the packet length data storage 8. The reference packet length data set is shortened and corrected by the adjustment data fm, and the next transmission to the partner terminal is performed by a transmission signal having the corrected packet length. Then, when the transmission signal from the wireless communication terminal is received again after the conference is over and the attendees leave the room, the level of the received signal is increased, and the packet stored in the packet length data storage 8 is The length data is subjected to expansion correction by the adjustment data fm, and the next transmission to the partner terminal is performed in a state in which the communication performance is improved by the transmission signal of the long corrected packet length.

As described above, according to the present embodiment, the reception level data fL of the reception signal Fr from the partner terminal is detected by the reception level detector 5, and the ID data f of the partner terminal is detected.
I is extracted by the partner terminal ID extraction circuit 6 and is adjusted and retrieved from the adjustment data output circuit 7 according to the reception level.
The packet length data corresponding to the partner terminal ID is adjusted and corrected as necessary, and is stored again. At the time of transmission to the partner terminal, a packet format is configured based on the adjusted packet length and transmission is performed. Therefore, it is possible to always perform transmission and reception with the maximum communication capacity according to the transmission and reception environment.

[0020]

According to the present invention, in a predetermined service area, a plurality of wireless communication terminals store packet length data in packet length data storage means based on packet length data stored in correspondence with ID data of a partner terminal. In a state where the packet length is set, data packets are mutually transmitted via the wireless channel. However, ID data of the other terminal is detected from the received signal by the ID detecting means, and the received data is received by the level detecting means. The reception level of the signal is detected, and adjustment data for correcting the packet length data is output from the adjustment data output unit based on the reception level, and the correction unit outputs the packet length data stored in the packet length data storage unit. The correction is performed based on the adjustment data, and at the time of transmission, the transmission control unit corrects the correction corresponding to the ID of the partner terminal. Since the packet length data is read from the packet length data storage means and transmitted at this packet length, the maximum communication capacity always reduces the loss of packets due to errors by the optimal packet length corresponding to the transmission / reception environment. It becomes possible to perform data transmission in the state.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a communication capability and an error rate with respect to a packet length.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Antenna, 2 ... Wireless receiver, 3 ... Wireless transmitter, 5 ...
Reception level detector, 6 ... Terminal terminal ID extraction circuit, 7 ...
Adjustment data output circuit, 8 ... Packet length data storage, 1
0: packet length setting circuit, 11: destination terminal ID extraction circuit, 12: controller, 13: terminal, antenna switch.

Claims (1)

[Claims] 1. An ID detecting means for transmitting data via a wireless channel to a plurality of wireless communication terminals within a predetermined service area, and detecting ID data of a partner terminal from a received signal. Level detection means for detecting a reception level of a reception signal; packet length data storage means for storing packet length data corresponding to ID data of a partner terminal; and a reception level detected by the level detection means. Adjustment data output means for outputting adjustment data for correction of packet length data stored in the packet length data storage means; and adjustment data from the adjustment data output means, stored in the packet length data storage means. Correction means for correcting the packet length data, and a corrected packet corresponding to the ID of the other terminal at the time of transmission A wireless communication system, wherein the wireless communication terminal is provided with transmission control means for reading long data from the packet length data storage means and performing transmission based on the packet length data.