KR100263652B1 - Wireless local area network transmission output control method and device - Google Patents

Abstract

In a wireless local area network (LAN) station transmission output control method having an access point (AP) having a plurality of client stations and one bridge function, when the reception level of the signal received at the client station is low, Performing a transmission output level control request to the AP; And the AP receiving the transmission power level control request, requesting all stations to switch the transmission power mode. When performing mutual data transmission and reception, a specific station among the plurality of client stations constituting the wireless channel environment performs data transmission and reception with the AP smoothly, but any station may cause a deterioration of the wireless channel environment due to distance or barrier. In this case, according to the present invention, an improved wireless communication channel environment can be established by performing transmission output level control to overcome a poor communication environment through the AP, and reduce network traffic. In addition, when a plurality of client stations constituting a wireless channel environment perform mutual data transmission / reception, the plurality of client stations and the AP set thresholds so that the station transmitting the finest signal can transmit and receive signals. It has the function of increasing the processing of the network and reducing the traffic by enabling data communication with the stations.

Description

Method and apparatus for controlling wireless LAN station transmission output

The present invention relates to the implementation of an optimal transmission output control function of a wireless local area network (LAN) station, and more particularly, to control the transmission output level of a client station having a poor communication environment among a plurality of client stations. The present invention relates to a wireless local area network station transmission output control method and apparatus for enabling data communication with a station of the present invention.

1 is a block diagram showing an overall system for a description of a typical wireless LAN structure and operation, the entire wireless LAN system is a plurality of wireless network modules (WNM) (0, 1, 2, ..., N It is composed of Each station that has a wireless network module (WNM) has a wireless antenna (ANT). The wireless antenna for each station may be configured to have two antennas with diversity functions to reduce the multipath fading effects that occur in most wireless environments. The wireless network module (WNM0) is connected to a bridge module (10), which is an access point connecting a wired network and a wireless network, and the other WNMs (1) to WNM (N) are wireless client network modules, corresponding to client stations respectively. And PCMCIA type II or ISA bus. One or more bridge modules can also be connected to a wired Ethernet cable to connect the wired network to the wireless network. As a result, each client station may receive a control signal from the server 20 through an Ethernet to which the access point 10 is connected. Communication between the access point 10 to which the WNM0 is connected and the client station to which the WNM (1) -WNM (N) is connected via the bus interface are performed wirelessly at a designated transmission power level through a single channel. A spread spectrum modulation and demodulation technique is used.

In the conventional wireless LAN system of FIG. 1, an access point having a bridge function performs data transmission / reception with a plurality of wireless LAN client stations, when the level of the signal received from the client station is out of the reference signal level value. There is no function to automatically set the output power level control of the station, and the wireless LAN client station requests the access point 10 to transmit the output signal output level control when the signal received from the access point is out of the reference signal level value. As a result, the client station and the access point 10 cannot maintain optimal data transmission and reception, and also, when the wireless LAN client station performs data transmission and reception, an initial received signal strength indicator (RSSI) is received. Of) By attempting to detect the carrier signal by setting the Threshold Value to a specified default value, a station having a fine signal output among a plurality of client stations performs continuous bad data transmission and reception, which increases network traffic and degrades performance. A problem arises.

The technical problem to be solved by the present invention is to solve the above problems, the wireless local area network station to control the transmission output level of the client station having a poor communication environment of the plurality of client stations to enable data communication with the plurality of stations It is to provide a transmission output control method and apparatus.

Another technical problem to be solved by the present invention is to set the threshold value of the initial received signal strength indicator to a value of a station having a fine signal output among a plurality of client stations, rather than a designated default value, thereby enabling more optimal data communication. It is to provide a local area network station transmission output control method and apparatus.

1 is a configuration diagram of a wireless whole local area network (LAN) system.

2 is a configuration diagram of a wireless LAN client system to which the present invention is applied.

3 is a configuration diagram of a wireless LAN network.

4A is a diagram illustrating a station transmission signal output map.

4B is a diagram illustrating a new map.

Fig. 5 is a flowchart showing a delivery output control algorithm.

Fig. 6 is a flowchart showing the threshold resetting algorithm of the transmission output.

<Description of the code | symbol about the principal part of drawing>

200 ... MAC controller, 210 ... baseband I / Q spreader / despreader

220 ... IF modulator, 250 ... up-down converter

260 ... power amplifier, 270 ... low noise amplifier

290 ... BPF, 300 ... antenna

310 ... A / D converter. 320 ... CCA output and threshold reset section

340 ... Master clock generator, 350 ... Flashram

360 ... SRAM, 370 ... Reference Clock Generators

380 ... IF VCO, 390 ... Dual PLL Synthesizer

400 ... RF VCO, 500 ... Host Computer

600 ... Threshold refresh section

The present invention provides a wireless local area network (LAN) station transmission output control method having a plurality of client stations and an access point having one bridge function. If it is low, performing a transmission output level control request to the access point; And the access point receiving the transmission power level control request, requests all stations to switch the transmission power mode. Preferably, the client station has a map for output power level compensation for a plurality of stations.

Another object of the present invention is to provide a wireless local area network (LAN) station transmission output control apparatus having a plurality of client stations and an access point having one bridge function, when the reception level of a signal received at the client station is low. Means for performing a transmission power level control request to the access point; And the access point receiving the transmission output level control request provides a wireless LAN station transmission output control apparatus including means for requesting transmission output mode switching to all stations. Preferably, the client station has a map for output power level compensation for a plurality of stations.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of a wireless LAN client system to which the present invention is applied. The wireless client system includes a MAC controller 200, a baseband I / Q spreader / despreader 210, an IF modulator / demodulator 220, a BPF 230, 240, an up-down converter 250, an output amplifier (PA) 260. Low Noise Amplifier (LNA) 270, Switch 280, Transceiver Buffer 290, Dual Diversity Antenna 300, Master Clock Generator 340, Flash Ram 350, Static Ram 360, Reference Clock The generator 370 includes an IF VCO 380, a dual PLL synthesizer 390, an RF VCO 400, a host computer 500, and a threshold refresh unit 600. Here, the analog-to-digital converter 310, the CCA output and threshold reset unit 320, the received signal strength display reference generator 330 constitutes the threshold refresh unit 600.

In addition, the wireless LAN client system is connected to the host computer 500 by a PCMCIA bus or an ISA bus, and mutual data and control signals are transmitted and received. The MAC controller 200, the flash RAM 350, and the static RAM 360 are connected to a local bus, and the MAC controller 200 is a medium access controller (MAC) device for a wireless LAN. The CCA signal is received from the output and threshold reset unit 320, and performs a wireless communication protocol CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance).

The control data and the control clock are transferred between the MAC controller 200 and the baseband I / Q spreader / despreader 210, and the master clock generator 340 provides a master clock signal to the MAC controller 200. In addition, the MAC controller 200 provides a control signal for serial transmission and reception and a serial data signal to the dual PLL synthesizer 390. Here, the control signal for transmission and reception switching is provided to the switch 280.

The reference clock generator 370 supplies the reference clock to the baseband I / Q spreader / despreader 210 and the dual PLL synthesizer 390. The baseband I / Q spreader / despreader 210 differentially encodes a serial data stream input from the MAC controller 200 and then generates PN (Pseudo Number) barker code for each of the I and Q symbols. Exclusive OR, and spreads or despreads the IF signal input from the IF modulator 220 back into I and Q symbols.

The dual PLL synthesizer 390 receives a clock signal from the reference clock generator 370 and supplies an IF (Intermediate Frequency) signal to the IF modulator 220 through the IF VCO 380, and the IF modulator 220 is provided. The IF signal is received as an input, and the baseband digital I and Q signals are converted into IF signals and supplied to the up-down converter 250 through a band pass filter (BPF) 230 or input from the up-down converter 250. The modulated IF signal is converted into baseband digital I and Q signals through the BPF 240 and provided to the baseband I / Q spreader / despreader 210. In addition, the output of the IF VCO 380 is supplied to the dual PLL synthesizer 390.

The Surface Acoustic Wave (SAW) Bandpass Filter (BPF) 230, 240 between the IF modulator 220 and the up-down converter 250 is used to shape the sidelobe (Sidelobe) signal of the IF signal.

The up-down converter 250 converts a spreading signal input through the BPF 230 from the IF modulator 220 into an ultrahigh frequency signal and supplies it to an output amplifier PA 260 or is input from a low noise amplifier LNA 270. The microwave signal is converted into an IF signal and provided to the IF modulator 220 through the BPF 240.

The RF VCO 400 is controlled by the control voltage of the dual PLL synthesizer 390, and the center frequency of its output frequency is generated as the difference between the channel frequency and the IF demodulation signal so that the up-down converter 250 and the dual PLL synthesizer 390 Is provided.

The center frequency of the output frequency of the IF VCO 380 does not change, and therefore a small tuning voltage change is required.

The signal converted by the up-down converter 250 is amplified by the output amplifier 260 and band-filtered by the BPF 290 and then transmitted through the diversity antenna 300 or input through the diversity antenna 300. Is filtered by the BPF 290, amplified by the low noise amplifier 270 and supplied to the up-down converter 250. The switch 280 for switching the transmission and reception of the antenna 300 is connected between one end of the output amplifier 260 and the low noise amplifier 270 and one end of the BPF 290.

The threshold refresh unit 600 receives an analog received signal strength indicator signal output from the IF modulator 220 and controls the reference signal generator 330 to generate a reference voltage determined by the resistors R1 and R2. The A / D converter 310 converting the digital signal to the digital signal and the threshold data from the MAC controller 200 are compared to reset the threshold value provided from the MAC controller 200 when the RSSI_hexa value is large. When the CCA is set to high, and the RSSI_hexa value is smaller than the threshold provided from the MAC controller 200, the CCA output and threshold reset unit for setting the RSSI_hexa value as the threshold and setting the CCA output to low ( 320, the CCA signal is transmitted to the MAC controller 200.

In the wireless LAN network configuration of FIG. 3, a plurality of client stations S1, S2, ..., SN transmit and receive according to the distance or channel environment of each station so as to obtain an optimal BER in performing data transmission and reception. By controlling the output level of the signal, the receiver has an output level control function so that the receiver can maintain the optimum signal level. Output level compensation data is transmitted to a specific station through an access point (AP).

After the AP controls the initial transmission output in step 31 of FIG. 5, in step 33, the transmission output control needs to be generated or transmitted to the stations that are currently connected through the control channel (the channel where the AP communicates with each station). When a transmission output level control request frame is received from the station, an information packet indicating a switch to the "transmission output control mode" is transmitted to all the multiple stations. Stations that have received the information packet indicating the switch to the "output output control mode" switch to the mode for transmission output control (step 35). The AP instructs the sequence to send out a random signal at a predetermined transmission output for a predetermined time by sequentially polling the stations currently established (step 37).

All of the client stations transmit random signals through the antenna with a predetermined transmission power when they are polled by the AP.

The other stations that are not polled detect the signal output from the specific client station being polled to determine whether it is an appropriate received signal output, and then select one of three terms: increase output, decrease output, and maintain current output. (Hereinafter referred to as "output level update request register"). When the process ends in step 39, the AP receives the value of the output level update request register from each station through the control channel. The AP returns this information to the station that was polled for transmission output control, so that a specific client station making a transmission output level control request can obtain compensation information for the received signal level obtained when the signal transmitted by the AP reaches another specific station. (Step 41). This may be stored in a table (hereinafter referred to as "outgoing signal output map") to selectively determine an appropriate outgoing output for each station to communicate with (step 43).

When the process ends, the AP repeats the process by polling the remaining stations. After the AP polls all stations that have made a transmission power level control request, each station has a transmission signal output map for the other stations except itself, and has a transmission signal output map of FIG. 4A. As a result, when one station intends to perform data communication with another station through the wireless channel, the optimal transmission signal output for the target station is read from the transmission signal output map to determine the output of the transmission signal. The transmission signal output map indicates that the AP or the corresponding station enters the transmission output control mode when a new station is connected to the AP, or when the channel status is deteriorated due to movement or obstacle, and thus its received signal level is out of an appropriate value. You can update by asking for a switch.

In the case where the existing N stations of FIG. 4B are connected, the AP informs all stations of the transmission output control mode switching to control the transmission signal output for the newly connected station N + 1 and the newly connected station N +. Poll 1 to send an arbitrary signal at a predetermined transmission output. Existing stations that are already connected to the AP detect the received signal level from their receiving circuit and store the information on output compensation in their output level update request register and transmit it to the AP. Update the output map as well.

The newly connected station prepares a transmission signal output map based on the transmission output compensation information received from the AP. When performing the transmission output control request, transmission and reception are performed at the optimal transmission signal level during communication between stations, so that low BER and power consumption can be reduced, and when a new station is connected or when an incorrect reception signal level is detected. Since the transmission output control mode switching request is generated once, the time and burden required to perform the algorithm are relatively small. A flowchart for the algorithm of the above scheme is shown in FIG. It is composed of software to request and respond to each other between client stations through the frame. In the frame, there is a bit set to distinguish the AP from the station. However, in the actual hardware, the AP and the station have the same structure and the AP is connected to the Ethernet module. That's a big difference. As described above, the transmission / reception path of the present invention consists of the host computer, MAC controller means, IF means, RF means, transmission and reception antenna.

A specific client station requests signal output level control through the AP when a signal received from a number of other client stations, including the AP, is out of a specified value and the signal reception level is not appropriate, and the AP receives a signal transmission level control request. Signal output level compensation data is collected from a number of client stations except client stations and retransmitted to a specific client station. As a result, a specific station has an output signal output map for all stations. In addition, by setting the threshold value of the initial received signal strength indicator (RSSI) to the value of the client station having the finest signal transmission level among the plurality of client stations, the wireless channel environment is optimally maintained. To lower network traffic and achieve the highest throughput.

As described above, the present invention relates to the implementation of an optimal transmission output control function of a wireless LAN station. In a network structure having an AP having a plurality of client stations and one bridge function, the client station includes an AP and a plurality of other clients. As the signal received from the station deviates from the prescribed value, the AP and each station has a function of requesting signal transmission output level control when the signal reception level is not suitable. The client station transmits a transmit power control request dataframe to the AP, and the AP receives the data frame to all the stations indicating that the client switches to the transmit power level control mode. It transmits transmission output control frame to all stations including AP at predetermined transmission output level to one station. Each station that receives the transmission output control frame senses its own reception output level and transmits an output level compensation information frame for the specific station requesting the transmission output control request frame to the AP.

In connection with performing the reference threshold reset algorithm of FIG. 6, the initial plurality of client stations and the AP set a specified threshold (step 51). A received signal strength indicator (RSSI) signal output from the IF modulator 220 of FIG. 2 is received as an input, digitized through the A / D converter 310, and converted into a hexadecimal RSSI_hexa value ( Step 53). The newly converted RSSI_hexa value is compared with the threshold value provided from the MAC controller 200 in the CCA output and threshold value reset unit 320 of FIG. 2 (step 55). Set the threshold value provided by the controller (step 57), and set the Clear Channel Assessment (CCA) to high (step 61), wherein the RSSI_hexa value is the threshold value provided from the MAC controller 200. If smaller, by setting the RSSI_hexa value to a threshold (step 59) and setting the CCA output to low (step 63), many client stations and APs set that threshold to the station sending the finest signal. It has the function of increasing the processing of the network and reducing the traffic by enabling data communication with the station.

As described above, according to the present invention, when a plurality of client stations constituting a wireless channel environment perform mutual data transmission and reception, a specific station among the plurality of client stations performs data transmission and reception with the AP smoothly, but a plurality of clients Any of the stations can establish an improved wireless communication channel environment by performing transmission power level control of a station having a poor communication environment through the AP when there is a deterioration of the wireless channel environment due to a distance or a barrier. Reduce traffic

In addition, when a plurality of client stations constituting a wireless channel environment perform data transmission and reception with each other, the plurality of client stations and the AP set a threshold that enables signal reception of a station transmitting the finest signal to the plurality of stations and data. Enables communication to increase network throughput and reduce traffic.

Claims (7)

In a wireless local area network (LAN) station transmission output control method having a plurality of client stations and an access point having one bridge function, When the reception level of the signal received at the client station is low, performing a transmission output level control request to the access point; And The access point having received the transmission power level control request, the wireless LAN station transmission output control method comprising the step of requesting all stations to output power mode switching. The wireless LAN station transmission output control method according to claim 1, wherein the client station has a map for transmission output level compensation for a plurality of stations. The method of claim 2, wherein the transmission output mode switching request step The initial plurality of client stations and the AP setting a specified threshold; Receiving a received signal strength indicator (RSSI) signal as an input and converting the signal to a digitized value; Comparing the newly converted digital value with a threshold provided from the medium access controller; And In the comparing step, if the digital value is large, the threshold provided from the medium access controller is reset, the clear channel assessment is set high, and if the digital value is smaller than the threshold provided from the medium access controller, And setting the digital value to a threshold and setting the CCA to low. In a wireless local area network (LAN) station transmission output control apparatus having an access point having a plurality of client stations and one bridge function, Medium access controller (MAC) means for performing a transmission output level control request to the access point when the reception level of the signal received at the client station is low; And And the access point receiving the transmission power level control request includes other medium access controller means for requesting all stations to switch the transmission power mode. The wireless LAN station transmission output control apparatus according to claim 4, wherein the client station has a map for transmission output level compensation for a plurality of stations. The wireless LAN station transmission output control apparatus according to claim 5, further comprising a threshold refresh unit for detecting a signal of a station having the finest signal transmission level. 7. The digital display device of claim 6, wherein the threshold refresh unit receives an analog received signal strength indicator signal and converts the digital signal into a digital signal under the control of a reference signal generator for generating a reference voltage determined by resistors. When the converted digital signal value is larger by comparing the converted signal with the threshold provided from the medium access controller, the threshold provided from the medium access controller is set as a reset value, and when the digital signal value is smaller than the threshold provided from the medium access controller, And a threshold value reset section for setting the digital signal value to a threshold value.

Images