JP4173886B2 - Wireless communication network system, wireless terminal device, and communication control method for wireless communication network - Google Patents

Wireless communication network system, wireless terminal device, and communication control method for wireless communication network Download PDF

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JP4173886B2
JP4173886B2 JP2005316406A JP2005316406A JP4173886B2 JP 4173886 B2 JP4173886 B2 JP 4173886B2 JP 2005316406 A JP2005316406 A JP 2005316406A JP 2005316406 A JP2005316406 A JP 2005316406A JP 4173886 B2 JP4173886 B2 JP 4173886B2
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base station
wireless
throughput
load status
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英雄 安達
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富士通株式会社
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  The present invention relates to a wireless communication network system, a wireless terminal device, and a wireless communication network communication control method suitable for use in a wireless LAN (Local Area Network).

  FIG. 12 is a block diagram showing a communication system to which a wireless LAN is applied. In the example shown in FIG. 12, a wireless LAN (wireless communication network) 100A is provided by two wireless base stations 101A and 101B connected to the wired network 104, respectively. And 100B are formed.

  Each of these wireless LANs 100A and 100B is a system for connecting a plurality of wireless terminals (terminal stations) 102 to a network without a cable. Each wireless base station 101A, 101B is a beacon in each wireless area 103A, 103B. A plurality of wireless terminals 102 existing in each of the wireless areas 103A and 103B are controlled by periodically broadcasting a synchronization frame signal called "." That is, the range in which beacons from the wireless base stations 101A and 101B reach can be defined as the wireless areas 103A and 103B of the wireless LANs 100A and 100B.

Therefore, the wireless terminal 102 existing in the wireless area 103A or 103B is connected to the wired terminal 105 connected to the wired network 104 or other wireless terminal 103A or 103B via the wireless base station 101A or 101B. Communication with the wireless terminal 102 can be performed.
By the way, a method called a spread spectrum (hereinafter abbreviated as SS (Spread Spectrum)) is used as a wireless communication method in the medium-speed wireless LAN as described above. This SS system uses a very wide signal band compared to the usual system that uses a specific limited frequency band, and performs communication at a low output that can be called almost noise at a certain frequency. It is.

  In this SS system, for example, as shown in FIG. 13, the input pulse train is narrow-band modulated (primary modulation), and the spectrum subjected to primary modulation is further spread-modulated (secondary modulation), so that the spectrum is intentionally expanded and transmitted. It is realized by doing. The spread spectrum has higher redundancy than the original narrowband modulation signal and is resistant to noise and fading. On the receiving side, the received signal is subjected to secondary demodulation (spread demodulation) and then subjected to primary demodulation to obtain an output pulse train.

  The SS system as described above further includes two systems called direct spreading (hereinafter abbreviated as DS (Direct Sequence)) and frequency hopping (hereinafter abbreviated as FH (Frequency Hopping)). The DS method is a method of performing secondary modulation using a noise-like pulse train that is much faster than an input pulse train in which information is encoded. In the FH system, a frequency band of a predetermined width is divided into a plurality of channels, and the plurality of channels are sequentially used in a predetermined pattern (FH pattern) as a carrier frequency of a normal narrowband modulation signal. This is a method of transmitting by switching to. Each of these DS and FH systems is intended to reduce the transmission time as much as possible by spreading the frequency band of the carrier wave so that many users can use the frequency band effectively.

  The wireless LAN described above employs this FH method. When communication using the FH method is performed using the wireless LANs 100A and 100B described above with reference to FIG. Thus, the wireless terminal 102 in its own wireless area 103A, 103B is notified.

  By the way, when there is a single FH system network, if there is no device that sends out radio waves in the same band in the vicinity, the network will not receive radio wave interference from others and will exhibit its original throughput performance. To do. However, when other wireless LAN systems exist in the vicinity (for example, when a plurality of (three in the figure) wireless areas 103A to 103C overlap each other as shown in FIG. 14), the same frequency band should be used. Therefore, when the same frequency is used at the same time or when adjacent frequencies are used, the throughput deteriorates due to mutual radio wave interference. As the number of peripheral networks increases, the degree of interference increases and the throughput deterioration rate also increases. In FIG. 14, 100C is a wireless LAN, 101C is a wireless base station in the wireless LAN 100C, and 103C is a wireless area of the wireless base station 101C.

  In Japan, the number of channels in the frequency band that can be used in the wireless LAN system as described above is 23. In the FH system, the operation of making a round of these 23 channels with a predetermined FH pattern is repeatedly performed. Therefore, when there is a radio wave having a frequency that can interfere with the frequency band, there is a case where interference occurs once in a cycle of 23 channels of frequency with a predetermined FH pattern in accordance with the frequency of the interference radio wave itself. There are two cases where interference occurs at a frequency adjacent to the frequency of the interference radio wave.

  In the case of the same frequency (that is, when the frequency in FH matches the frequency of the interference radio wave), communication is possible by dividing the usage rate in that frequency band, but in the case of adjacent frequencies (that is, in FH) If the frequency is adjacent to the frequency of the interfering radio wave), it is simply a disturbance. If there is one other wireless base station in the vicinity that has the possibility of radio wave interference, the communication performance will be reduced by a maximum of 2.5 / 23 = 10.8%. If the number of base stations is 5, for example, the rate of decrease is 12.5 / 23, which is 54% at maximum.

  Therefore, in the wireless LAN system adopting the FH method, when there are a plurality of networks, the radio wave interference is not avoided, but frequency interference is generated with a certain probability so that the ratio does not deviate more than a certain value. To use the hopping pattern. For example, in the technique disclosed in Japanese Patent Laid-Open No. 7-15443, when a certain radio base station tries to communicate using a predetermined FH pattern, there is a network using the same FH pattern in the vicinity. The frequency interference is avoided by avoiding the use of the FH pattern and using another FH pattern. However, even if different FH patterns are used, there is a sufficient possibility that interference occurs due to frequency coincidence or adjacent during FH in each wireless LAN, and radio wave interference cannot be reliably avoided.

On the other hand, the transmission path performance of a wireless LAN is usually about 1 to 2 Mbps (about 1/10 to 1/5 of an existing wired LAN). Therefore, when connections of many wireless terminals are concentrated on one wireless base station, the load between the base stations with a small number of connected terminals is biased, and there is a significant performance difference between wireless terminals used in the same area. .
Moreover, the CSMA / CA (Carrier Sense Multiple Access / Collision Avoid) + Ack method of the MAC (Media Access Control) layer protocol used in the wireless LAN is widely used in the existing wired LAN. Similar to / CD (Carrier Sense Multiple Access / Collision Detect) method, but differs in the following two points.

That is, first, in a wireless LAN, a control frame (synchronization frame) is periodically transmitted from a wireless base station, and a control frame is also transmitted irregularly from each wireless terminal. The transmission is obstructed.
Second, since clear collision detection is not possible, as a method for confirming frame delivery to the other party, the sender sends a reception response (Ack) back to the sender, and the sender receives the notification to end the notification normally. Check. Therefore, the frame transmission source can recognize that the frame transmission has been performed without causing a collision (collision) only after receiving the reception response (Ack) from the transmission destination.

  Prior to data transmission, a control frame RTS (Request To Send) and a CTS is determined between the transmission source and the transmission destination in order to determine collision (that is, data unreachable) at an early stage and to secure a dedicated time for the transmission path. (Clear To Send) is also exchanged. However, when the RTS / CTS frame exchange as described above is performed in a situation where the transmission line load is light and the occurrence of collision is small, it takes a long time to transmit one data frame.

Due to such a complicated protocol, the difference between the wireless LAN and the wired LAN tends to be large in the execution throughput, and depending on the network application, there is a case where poor response is easily noticeable when using the wireless LAN.
The present invention was devised in view of such a problem, and provides a wireless communication network system, a wireless terminal device, and a communication control method for a wireless communication network, which have improved throughput in a network system such as a wireless LAN. With the goal.

In order to achieve the above object, a wireless communication network system (Claim 1) of the present invention includes a plurality of base station devices having wireless areas that are close to or overlap each other, and any one of these base station devices. One or more wireless terminal devices that perform wireless communication with each other, and when a plurality of base station devices receive probe signals from the wireless terminal devices, the load status of each base station device is used as a probe response. In addition to providing a load status transmission unit to be sent back to the wireless terminal device, the wireless terminal device transmits a probe signal to search for a base station device existing in the vicinity, and a throughput storage unit that stores necessary predetermined throughput as information Probe signal transmission unit to be sent back from the base station apparatus according to the probe signal transmitted by the probe signal transmission unit And a probe response reception unit which receives a probe response that has been set to the load situation, the optimum on the basis of the throughput stored in the load status and throughput storage unit in the probe responses received by the probe response reception unit A base station apparatus selection unit for selecting and connecting a base station apparatus in a load state is provided.

  At this time, if the load status of the base station device connected to the wireless terminal device is not suitable for the throughput stored in the throughput storage unit, the base station device selection unit transmits the probe signal using the probe signal transmission unit. Based on the load status sent back from the base station device in response to the received probe signal and the throughput stored in the throughput storage unit, the base station device in the optimum load status is selected and changed to reconnect. (Claim 2).

The wireless terminal device according to the present invention (Claim 3) performs wireless communication with any one of a plurality of base station devices having wireless areas that are close to each other or overlapped with each other, and is assigned in advance. A throughput storage unit that stores necessary throughput as information, a probe signal transmission unit that transmits a probe signal to search for a base station device existing in the vicinity, and a base station according to the probe signal transmitted by the probe signal transmission unit A probe response receiving unit that receives a probe response set with a load status sent back from the station apparatus , a load status in the probe response received by the probe response receiving unit, and a throughput stored in the throughput storage unit And a base station device selection unit that selects and connects a base station device having an optimal load condition based on There.

  At this time, if the load status of the connected base station apparatus is not suitable for the throughput stored in the throughput storage unit, the base station apparatus selection unit transmits the probe signal transmitted by the probe signal transmission unit. In accordance with the load status sent back from the base station device and the throughput stored in the throughput storage unit, the base station device with the optimal load status is selected and changed to reconnect. (Claim 4).

  Further, a communication control method for a wireless communication network according to the present invention (Claim 5) includes a plurality of base station devices having wireless areas that are close to each other or overlapped with each other, and wireless communication with any one of these base station devices. The present invention is applied to a wireless communication network including one or more wireless terminal devices that perform the above, and a necessary throughput is given to the wireless terminal device as information in advance, and the wireless terminal device exists in the vicinity. A probe signal is transmitted to search for a base station device to be transmitted, a load status is transmitted from the base station device that has received the probe signal to the wireless terminal device, and the load status sent back from the base station device is given in advance. Based on the throughput, a base station apparatus having an optimum load condition is selected and connected to the wireless terminal apparatus.

  At this time, if the load status of the base station device connected to the wireless terminal device is not suitable for the throughput given in advance, the probe signal is transmitted from the wireless terminal device to the base station devices existing in the vicinity. Based on the load situation sent back from the base station apparatus according to the probe signal and the throughput, the base station apparatus with the optimum load situation is selected and changed, and the wireless terminal apparatus is reconnected. (Claim 6).

According to the above-described radio communication network system, radio terminal apparatus, and radio communication network communication control method of the present invention, when there are a plurality of connectable base station apparatuses when the radio terminal apparatus connects to the base station apparatus The wireless terminal device can select and connect a base station device that can provide the throughput required in the wireless terminal device from among the base station devices that have transmitted the load status. And the throughput of the entire wireless communication network can be greatly improved.
Also, when the throughput required on the wireless terminal device side changes after the wireless terminal device and the base station device are connected and actual communication starts, or when the load status on the base station device side changes According to the change, the base station apparatus of the connection destination can be selected / changed to the one with the optimal load status, so that efficient system operation can always be performed in consideration of the throughput of the entire wireless communication network.

Embodiments of the present invention will be described below with reference to the drawings.
First, the configuration of a wireless LAN (wireless communication network system) to which this embodiment is applied will be described with reference to FIG.
FIG. 3 is a block diagram showing a plurality (three in the figure) of wireless LANs (wireless communication networks) 10 in which the wireless areas 3 overlap each other. In the example shown in FIG. 3, the wireless areas 3 are connected to the wired network 4. Each of the three wireless base stations (wireless communication network base station devices) 1 forms a wireless LAN 10.

  Each of these wireless LANs 10 is a system for connecting a plurality of terminal stations (wireless terminal devices) 2 to a network without a cable. Each wireless base station 1 has a synchronization frame signal called a beacon in its wireless area 3. Is periodically broadcast to control a plurality of terminal stations 2 existing in each wireless area 3. That is, the range in which the synchronization frame signal from each radio base station 1 reaches can be defined as the radio area 3 of each radio LAN 10.

  Accordingly, the terminal station 2 existing in the wireless area 3 communicates with the wired terminal 5 connected to the wired network 4 and other terminal stations 2 existing in the wireless area 3 via the wireless base station 1. Can be done. Each terminal station 2 is configured as a data communication mobile terminal that performs data communication, for example, by a personal computer.

  By the way, the above-described radio base station 1 has a hardware configuration as shown in FIG. 4, for example. That is, as shown in FIG. 4, the radio base station 1 includes an MPU (Micro Processor Unit) 21, a PCMCIA (Personal Computer Memory Card International Association) controller 22, a LAN controller 24, an SRAM 25, a FLASH ROM 26, a DRAM 27, and an EPROM 28 via a bus 29. They are connected to each other.

Here, the MPU 21 controls each component connected via the bus 29 and is connected to the terminal station 2 under the radio base station 1 (ie, the radio station 3 existing in the radio area 3). The terminal station 2) is managed.
The PCMCIA controller 22 is connected to a wireless LAN card 23 that functions as a wireless communication unit, and controls the wireless LAN card 23. Note that the wireless LAN card 23 has a hardware configuration as will be described later with reference to FIG. 5. In the terminal station 2, the wireless LAN card 23A (see FIG. 5) having the same configuration is provided as a wireless communication unit. It has been.

The LAN controller 24 is connected to the wired network 4 and functions as an interface between the wired network 4 and the wireless base station 1.
The SRAM 25, the FLASH ROM 26, the DRAM 27, and the EPROM 28 store programs, program operation data (for example, connection information between the radio base station 1 and the terminal station 2, management information of the terminal station 2, etc.), communication data, and the like. The storage unit 20 is configured.

  On the other hand, the terminal station 2 is configured, for example, by connecting a PCMCIA standard wireless LAN card 23A (see FIG. 5) to a personal computer, and can transmit and receive data to and from the wireless base station 1 using the wireless LAN card 23A. It has become so. The wireless base station 1 can also transmit and receive data to and from the terminal station 2 by using the wireless LAN card 23 (see FIG. 4) described above.

  The wireless LAN cards 23 and 23A (wireless communication units of the wireless base station 1 and the terminal station 2) have a hardware configuration as shown in FIG. 5, for example. That is, as shown in FIG. 5, the wireless LAN cards 23 and 23A are configured to include a PCMCIA interface 31, an MPU 32, a FLASH ROM 33, a DRAM 34, LSIs 35 and 36, a transmission / reception unit 37, and an antenna 38.

Here, the PCMCIA interface 31, MPU 32, FLASH ROM 33, DRAM 34, and LSI 35 are connected to each other by a bus 30, and a transmission / reception unit 37 having an antenna 38 is connected to the LSI 35 via the LSI 36.
The PCMCIA interface 31 exchanges data, signals, and the like with a processing unit (a processing unit such as a CPU (not shown in the PCMCIA controller 22 / terminal station 2) in the wireless base station 1) connected to the wireless LAN cards 23 and 23A. It is for doing.

The MPU 32 controls the wireless LAN cards 23 and 23A through the bus 30. The FLASH ROM 33 stores programs and the DRAM 34 stores program operation data and communication data. To store.
The LSI 35 connected to the bus 30 has functions as a MAC (Media Access Control) control unit 35a, a timer 35b, a serial interface 35c, and a first physical layer control unit (PHY control unit) 35d. The MAC control unit 35a performs data transmission order control when data is transmitted via a wireless line, and the first physical layer control unit 35d performs serial / parallel conversion processing on transmission signals and reception signals. Functions as a physical layer interface.

Furthermore, the LSI 36 has a function as a second physical layer control unit (PHY control unit) 36a, and the second physical layer control unit 36a performs a physical layer conversion process for transmission signals and reception signals. Functions as an interface.
The transmission / reception unit 37 connected to the LSI 36 transmits and receives wireless signals via the antenna 38.

Now, in the radio base station 1 and the terminal station 2 of the present embodiment, for example, functional configurations as shown in FIGS. 1 and 2 are realized by the above-described hardware configuration.
First, a functional configuration of the radio base station 1 of the present embodiment will be described with reference to FIG. That is, as shown in FIG. 1, the radio base station 1 of the present embodiment includes a frequency hopping control unit 50, a synchronization frame transmission processing unit 51, a data transmission processing unit 52, a data reception processing unit 53, an ACK transmission / reception unit 54, and an RTS. A transmission / reception unit 55, a CTS transmission / reception unit 56, a probe signal transmission processing unit 57, a probe response reception processing unit 58, a synchronization frame reception processing unit 59, a probe signal reception processing unit 60, a probe response transmission processing unit 61, a load status setting unit 62, It has functions as a transmission / reception byte number counter 63, a retransmission number counter 64, a terminal station retransmission number counter 65, an average data frame length counter 66, a CW value setting unit 67, and an RTS / CTS addition & maximum packet length setting unit 68. .

  Here, the synchronization frame transmission processing unit 51 periodically broadcasts a synchronization frame signal called a beacon into the wireless area 3 in order to control the terminal station 2 in the wireless area 3 of the wireless base station 1. By this synchronization frame signal, various control information set in the radio base station 1 is transmitted to each terminal station 2 as described later.

The data transmission processing unit 52 performs data transmission processing to the terminal station 2, and the data reception processing unit 53 performs data reception processing from the terminal station 2.
The ACK transmission / reception unit 54 performs transmission / reception processing of a reception confirmation notification signal (ACK). When the data reception processing unit 53 completes data reception from the terminal station 2, the ACK transmission / reception unit 54 receives the data from the terminal station 2 that is the data transmission source. While transmitting the confirmation notification signal (ACK), the data transmission processing unit 52 receives the reception confirmation notification signal (ACK) from the data destination terminal station 2 when data transmission is performed to the terminal station 2. is there.

  The RTS transmission / reception unit 55 performs transmission / reception processing of an RTS (Request To Send) frame as a control frame. The RTS frame is transmitted while the RTS frame from the terminal station 2 is received. That is, the RTS transmission / reception unit 55 performs RTS frame transmission processing before the data transmission processing unit 52 performs data transmission to the terminal station 2.

  The CTS transmission / reception unit 56 performs transmission / reception processing of a CTS (Clear To Send) frame as a control frame. When a dedicated time of the transmission path is secured according to the RTS frame from the terminal station 2, the CTS transmission / reception unit 56 On the other hand, a CTS frame is transmitted, while a CTS frame from the terminal station 2 is received. When the CTS frame is received by the CTS transmission / reception unit 56, the data transmission processing unit 52 starts data transmission to the terminal station 2.

In the present embodiment, whether or not to perform additional transmission of an RTS frame or a CTS frame is set by a function of an RTS / CTS addition & maximum packet length setting unit 68 described later.
The probe signal transmission processing unit 57 receives an instruction from the search unit 50a, which will be described later, and in order to scan the operation status of other wireless LANs 10 in the vicinity when the wireless base station 1 is activated, In response to the probe signal transmitted by the probe signal transmission processing unit 57, the probe response reception processing unit 58 transmits a probe response (probe response) transmitted from the wireless base station 1 constituting another wireless LAN 10. Signal).

  The probe response includes information related to the frequency hopping (FH) pattern and time already set by the radio base station 1. Although not shown in FIG. 1, the radio base station 1 according to the present embodiment relates to the set FH pattern and time when a probe signal from another radio base station 1 is received. A function for transmitting a probe response including information is also provided.

The synchronization frame reception processing unit 59 receives a synchronization frame signal (beacon) transmitted from another radio base station 1 during normal operation of the radio base station 1.
The frequency hopping control unit (FH control unit) 50 operates according to the flowcharts shown in FIGS. 6 and 7, and controls the timing and time of frequency hopping in its own station. The search unit 50a, frequency hopping selection -It has a setting unit 50b, a timer 50c, and a timing adjustment unit 50d.

  The search unit 50a causes the probe signal transmission processing unit 57 to transmit a probe signal to search for the presence / absence of another wireless LAN 10 in the vicinity when the wireless LAN 10 is started up by starting the wireless base station 1, and the probe signal When a probe response is received from another wireless base station 1 by the probe response reception processing unit 58 in response to the transmission (when another wireless LAN 10 exists in the vicinity), the other wireless LAN 10 (wireless base station) is detected from the probe response. The FH pattern and time in 1) are obtained.

  The frequency hopping selection / setting unit (FH selection / setting unit) 50b selects the FH pattern in the other wireless LAN 10 obtained by the search unit 50a as the FH pattern of the local station, and the FH obtained by the search unit 50a. The timing according to the selected timing is selected so that the FH of the pattern does not cause frequency interference with the FH in the other wireless LAN 10 based on the time of the time, and the FH of the pattern is executed at the selected timing. Is set in the timer 50c.

  The FH pattern selected and set by the FH selection / setting unit 50b and the time set in the timer 50c are given as control information in the synchronization frame signal by the synchronization frame transmission processing unit 51, and the transmission of the synchronization frame signal is performed. By this, each terminal station 2 is notified. Accordingly, each terminal station 2 that has received the synchronization frame signal analyzes the synchronization frame signal, reads the FH pattern and time, and executes the FH synchronized with the radio base station 1, thereby Communication is to take place.

In the timer 50c, the FH time is set by the FH selection / setting unit 50b as described above, and channels in the frequency band corresponding to the time indicated by the timer 50c are sequentially selected so that the FH is executed. It has become.
For example, when performing FH by making a round of 23 channels with a predetermined FH pattern every 400 msec per channel, the timer 50c starts counting from 0 and restarts counting from 0 when counting to 400 msec × 23 = 9200 msec. When the timer 50c indicates 0 to 400 msec, the first channel of the predetermined FH pattern is selected, and when the timer 50c indicates 400 to 800 msec, the second channel is selected. The 3rd to 22nd channels are selected, and the 23rd channel is selected when 8800 to 9200 msec is indicated.

  The FH time is a time (timer value) indicated by the timer 50c. For example, when the FH time of another radio base station 1 is 200 msec, if 1000 msec is set as the FH time of the own station in the timer 50c, the other radio base station 1 The station 1 and the own station execute the same frequency hopping of the same FH pattern in parallel with a time difference of 800 msec, that is, a timing shift of 2 channels.

  If the synchronization frame reception processing unit 59 receives a synchronization frame signal (beacon) from the other radio base station 1 during normal operation of the radio base station 1, the timing adjustment unit 50d receives the FH pattern from the synchronization frame signal. When the same pattern is obtained, the value of the timer 50c is changed according to the time (timer value) to adjust the FH timing of the own station with respect to the FH in the other wireless LAN 10. Thus, by correcting the value of the timer 50c with other wireless base stations 1 in the vicinity in this way, occurrence of frequency interference during long-time network operation is avoided as will be described later.

  The probe signal reception processing unit 60 receives a probe signal from the terminal station 2 in the wireless area 3 of the own station during normal operation, and the probe response transmission processing unit (load status transmission unit) 61 When the probe signal is received from the terminal station 2 by the probe signal reception processing unit 60, the load status set in the load status setting unit 62, which will be described later, is transmitted as a probe response to the terminal station 2 that is the source of the probe signal. Is.

  Then, the load status setting unit (load status transmission unit) 62 loads the load status of the wireless LAN 10 managed by the radio base station 1 [for example, (1) the number of terminals having a high load on the transmission path performance, (2) The number of transmission / reception bytes per unit time (a value counted by a transmission / reception byte number counter 63 described later) and the like are set as information in the probe response transmitted by the probe response transmission processing unit 61.

On the other hand, the transmission / reception byte number counter (load status detection unit) 63 counts the number of transmission / reception bytes per unit time in the wireless base station 1 as a load status in the wireless LAN 10.
The retransmission number counter (load status detection unit) 64 indicates the number of retransmissions per unit time from the wireless base station 1 to each terminal station 2 (the number of times retransmission was performed because of a collision during data transmission). It is counted as the load status.

The terminal station retransmission number counter (load status detection unit) 65 includes the number of retransmissions per unit time included in the received data from the terminal station 2 (the number of retransmissions performed until the terminal station 2 can transmit the data). Frequency) is counted as a load status in the wireless LAN 10.
The average data frame length counter 66 counts the average value of the data frame length transmitted / received to / from the terminal station 2.

  The CW value setting unit (changing unit) 67 operates according to the flowchart shown in FIG. 9, and the number of transmitted / received bytes per unit time counted by the transmitted / received byte number counter 63 and the number of retransmission counters 64 are counted. Depending on the number of retransmissions per unit time and the number of retransmissions per unit time from the terminal station 2 counted by the terminal station retransmission number counter 65, CW ( The contention window width is dynamically changed.

  The back-off time is a waiting time until the next data retransmission when a collision occurs during data transmission. In this embodiment, the number of transmitted / received bytes is described later with reference to FIG. The frame interval with less collision can be set by dynamically changing the CW value in accordance with the number of retransmissions and the number of retransmissions (the number of collisions / contention occurrences). The CW value set by the CW value setting unit 67 is transmitted to the data transmission processing unit 52 as control information at the time of retransmission, and is given as control information in the synchronization frame signal by the synchronization frame transmission processing unit 51. Each terminal station 2 is notified by transmission of a synchronization frame signal.

The RTS / CTS addition & maximum packet length setting unit (change unit) 68 operates according to the flowchart shown in FIG. 10, and sets the maximum packet length and the function (1) for setting and changing the addition state of the RTS / CTS frame. And (2) a function to be changed.
The function (1) is based on the RTS occurrence rate obtained based on the count results by the retransmission count counter 64 and the terminal station retransmission count counter 65 and the average data frame length counted by the average data frame length counter 66. / RTS / CTS frame use / non-use is determined by determining which transmission performance is better when the / CTS frame is added during frame transmission and when it is not used. It is a function to change automatically. The criteria for judging transmission performance will be described later with reference to FIG.

  The function (2) dynamically changes the maximum packet length at the time of frame transmission according to the number of retransmissions (the number of collision / contention occurrences) counted by the retransmission number counter 64 and the terminal station retransmission number counter 65. To do. According to the basic change criteria, when the number of retransmissions is large (when the number of collisions is large), the maximum packet length is set short and data is transmitted while fragmenting the data, while the number of retransmissions is small ( When the number of collision occurrences is small), the maximum packet length is set longer.

  The information on whether or not to add the RTS / CTS frame and the maximum packet length set by the RTS / CTS addition & maximum packet length setting unit 68 are used as control information at the time of data transmission to the data transmission processing unit 52. At the same time, the synchronization frame transmission processing unit 51 adds control information in the synchronization frame signal and notifies each terminal station 2 by transmission of the synchronization frame signal.

  Next, a functional configuration of the terminal station 2 according to the present embodiment will be described with reference to FIG. That is, as shown in FIG. 2, the terminal station 2 of this embodiment includes a synchronization frame reception processing unit 70, a synchronization frame analysis processing unit 71, a data transmission processing unit 72, a data reception processing unit 73, an ACK transmission / reception unit 74, and an RTS. It functions as a transmission / reception unit 75, a CTS transmission / reception unit 76, a probe signal transmission processing unit 77, a probe response reception processing unit 78, a throughput storage unit 79, and a base station selection unit 80.

  Here, the synchronization frame reception processing unit 70 performs reception processing of a synchronization frame signal (beacon) from the radio base station 1, and the synchronization frame signal received by the synchronization frame reception processing unit 70 is subjected to synchronization frame analysis. The above-described various control information that is analyzed by the processing unit 71 and included in the synchronization frame signal is read out, and the control information is used for control in the terminal station 2.

The data transmission processing unit 72 performs data transmission processing to the radio base station 1, and the data reception processing unit 73 performs data reception processing from the radio base station 1.
The ACK transmission / reception unit 74 performs transmission / reception processing of the reception confirmation notification signal (ACK). When the data reception processing unit 73 completes data reception from the radio base station 1, the ACK transmission / reception unit 74 transmits data to the radio base station 1 that is the data transmission source. On the other hand, when the data transmission processing unit 72 transmits data to the wireless base station 1, the reception confirmation notification signal (ACK) is transmitted from the wireless base station 1 as the data destination. To receive.

  The RTS transmission / reception unit 75 performs transmission / reception processing of an RTS (Request To Send) frame as a control frame, and the data transmission destination radio base station 1 secures a dedicated time for the transmission path in advance when data is transmitted to the radio base station 1. The RTS frame is transmitted to the mobile station while the RTS frame from the radio base station 1 is received. That is, the RTS transmission / reception unit 75 performs RTS frame transmission processing before the data transmission processing unit 72 transmits data to the radio base station 1.

  The CTS transmission / reception unit 76 performs transmission / reception processing of a CTS (Clear To Send) frame as a control frame, and the radio base station 1 when the exclusive time of the transmission path is secured according to the RTS frame from the radio base station 1 The CTS frame is transmitted to the radio base station 1 while the CTS frame from the radio base station 1 is received. When the CTS frame is received by the CTS transmission / reception unit 76, the data transmission processing unit 72 starts data transmission to the radio base station 1.

As described above, whether or not to perform additional transmission of the RTS frame or the CTS frame is determined by the RTS / CTS additional information provided as control information in the synchronization frame signal.
The probe signal transmission processing unit 77 transmits a probe signal to search for a wireless base station 1 existing in the vicinity before the terminal station 2 connects to the wireless base station 1.

  The probe response reception processing unit 78 receives a probe response transmitted from the wireless base station 1 existing in the vicinity in accordance with the probe signal transmitted by the probe signal transmission processing unit 77. In the probe response, as described above, the load status setting unit 62 of the radio base station 1 makes the load status of the wireless LAN 10 (for example, (1) the number of connected terminals with high load, (2) the number of transmitted / received bytes per unit time, etc. ) Is set.

The throughput storage unit 79 is preliminarily assigned with a throughput corresponding to a use (application) required by the terminal station 2 and stores it as information.
Then, the base station selection unit 80 determines the optimum based on the load status during the probe response received by the probe response reception processing unit 78 and the throughput necessary for the terminal station 2 stored in the throughput storage unit 79. The radio base station 1 under load is selected and connected. That is, the terminal station 2 selects, from the wireless base station 1 having a probe response, the one that can provide the required throughput by the function of the base station selection unit 80, and connects to the wireless base station 1. It has come to be.

  In addition, the base station selection unit 80 of the present embodiment uses the probe signal transmission unit 77 when the load status of the connected radio base station 1 is not suitable for the throughput stored in the throughput storage unit 79. Based on the load status sent back from the radio base station 1 according to the transmitted probe signal and the throughput stored in the throughput storage unit 79, the radio base station 1 with the optimum load status is automatically selected / It also has the function of changing and reconnecting.

Next, the operations of the radio base station 1 and the terminal station 2 of the present embodiment configured as described above will be described separately in items [1] to [5] with reference to FIGS. .
[1] Hopping Pattern / Timing Determination Operation First, the hopping pattern / timing determination operation in the radio base station 1 of the present embodiment will be described according to the flowchart (steps S1 to S7) shown in FIG.

  When starting up the wireless LAN 10 by starting up the wireless base station 1, normally, the terminal station 2 transmits a probe signal when connected to the wireless base station 1, and searches for the wireless base station 1 in the same manner as the wireless base station 1. The base station 1 searches for other wireless LANs 10 (other wireless base stations 1) existing in the vicinity (step S1). At that time, the search unit 50a causes the probe signal transmission processing unit 57 to transmit a probe signal.

Based on whether the probe response reception processing unit 58 has received a probe response from another radio base station 1 according to the probe signal, it is determined whether or not the radio base station 1 exists in the vicinity. (Step S2).
If no probe response is received from another wireless base station 1 (NO determination in step S2), there is no possibility of causing frequency interference with another wireless LAN 10, so the FH selection / setting unit 50b Selects an arbitrary hopping pattern (step S6), sets an arbitrary time (timer value) in the timer 50c (step S7), and starts frequency hopping (FH) (step S5).

  On the other hand, when a probe response from another wireless base station 1 is received (in the case of YES determination in step S2), the search unit 50a determines the FH in the other wireless LAN 10 (wireless base station 1) from the received probe response. And the FH selection / setting unit 50b selects the same FH pattern as the FH pattern of the own station (step S3), and sets the value of the timer 50c to the probe. After setting to a value that does not match the timer value (time) obtained from the response (for example, a value shifted by 800 msec or more) (step S4), frequency hopping (FH) is started (step S5).

By setting the value of the timer 50c as described above, the timing at which the FH according to the pattern does not cause frequency interference with the FH in the other wireless LAN 10 is selected.
As described above, the pattern and timer value selected / set in steps S3, S4, S6, and S7 are added as control information in the synchronization frame signal by the synchronization frame transmission processing unit 51 and notified to each terminal station 2. Each terminal station 2 that has received the synchronization frame signal performs FH synchronized with the radio base station 1 according to the FH pattern and timer value, and communicates with the radio base station 1.

  In this way, as shown in FIG. 3, when other wireless LANs 10 are present in the vicinity, frequency hopping of exactly the same pattern is executed with the hopping timing shifted, so that the frequency of the wireless LAN 10 of its own station It is possible to positively avoid the occurrence of frequency interference between the hopping and the frequency hopping of the other wireless LAN 10, and it is possible to reliably avoid a decrease in throughput due to the frequency interference.

Therefore, in a situation where a plurality of mutually coherent networks (wireless LANs 10) are adjacent to each other, it is possible to provide each wireless LAN 10 with the maximum radio wave throughput.
As a result of searching for wireless base stations 1 present in the vicinity, when a plurality of wireless base stations 1 exist in the vicinity and a plurality of different hopping patterns are used, The radio base station 1 that is most easily influenced by (ie, having the strongest reception strength of the received frame) is selected, and the hopping pattern and time (timer value) of the own station are set with reference to the hopping pattern and time. .

[2] Hopping Timing Correction Operation The hopping timing correction operation in the radio base station 1 of the present embodiment will be described according to the flowchart (steps S11 to S16) shown in FIG.
After the FH is started by the procedure described in FIG. 6, the channel change (that is, frequency hopping) is performed every 400 msec according to the value (time) indicated by the timer 50c as described above. If the hopping timing gradually shifts due to the performance error of each timer 50c between the wireless base station 1 and the surrounding wireless base station 1, if left as it is, there is a possibility that the mutual interference of the frequency occurs and the throughput is lowered. .

In order to avoid such mutual interference due to accumulation of errors of the timer 50c, in this embodiment, a hopping timing correction operation as shown in FIG. 7 is performed by the function of the timing adjustment unit 50d.
Whether or not the received frame is a synchronization frame signal from another radio base station 1 during normal operation of the radio base station 1, that is, a synchronization frame from another radio base station 1 by the synchronization frame reception processing unit 59. It is determined whether or not a signal has been received (step S11). When the synchronization frame signal is received (in the case of YES determination), the timing adjustment unit 50d refers to the control information included in the synchronization frame signal and determines whether or not the same hopping pattern is used (step S12). .

When it is determined that the same hopping pattern is used (in the case of YES determination), the timing adjustment unit 50d compares the timer value t1 in the received synchronization frame signal with the value t0 of the timer 50c of the own station. , T1> t0 is determined (step S13).
When it is determined that t1> t0 (in the case of YES determination), by returning the timer 50c of its own station, the value is set small so that a difference between the received timer value and a predetermined value (for example, 800 msec) or more occurs. On the other hand (step S14), when it is determined that t1 ≦ t0 (in the case of NO determination), the timer 50c of the own station is advanced to make the value equal to or greater than the received timer value and a predetermined value (for example, 800 msec). A large value is set so as to cause a difference (step S15).

Then, when the next synchronization frame signal is transmitted by the synchronization frame transmission processing unit 51, the new timer value set in steps S14 and S15 is set as control information in the synchronization frame signal, so that the radio base station The timer value for FH in each terminal station 2 connected to 1 is corrected (step S16).
In this way, by correcting the value of the timer 50c with other wireless base stations 1 in the vicinity, the time-dependent change of the timer 50c accompanying a long-time network operation causes the wireless LAN 10 of the local station to It can be avoided that the frequency hopping and the frequency hopping of another wireless LAN 10 gradually approach each other, thereby causing frequency interference, and more reliably avoiding a decrease in throughput due to frequency interference.

[3] Radio Base Station Selection Operation The radio base station selection operation of the terminal station 2 of this embodiment will be described according to the flowchart (steps S21 to S27) shown in FIG.
By the way, each terminal station 2 has a different amount of throughput and data concentration depending on its use (application). Therefore, as shown in FIG. The throughput of the entire network can be improved by selecting the connection-destination radio base station 1 according to the information every two.

Therefore, the terminal station 2 of the present embodiment performs the selection operation of the radio base station 1 as shown in FIG.
When the terminal station 2 is incorporated in the network, the throughput required by the terminal station 2 is estimated based on the network application used by the terminal station 2 and stored in the throughput storage unit 79.

When the terminal station 2 connects to the radio base station 1, the probe signal transmission processing unit 77 usually transmits a probe signal to the surrounding radio base station 1, and the probe from the radio base station 1 is transmitted. By receiving the response by the probe response reception processing unit 78, the wireless base station 1 existing in the vicinity is searched (step S21).
At this time, the radio base station 1 that has received the probe signal sends the load status set by the load status setting unit 62 back to the terminal station 2 that is the probe signal sending source by the probe response transmission processing unit 61 as a probe response. Accordingly, the probe response from the wireless base station 1 includes the load status of the wireless LAN 10 managed by each wireless base station 1.

  In the terminal station 2 that has received such probe responses from the plurality of radio base stations 1, the load status of these radio base stations 1 ((1) number of terminals having a high load with respect to transmission path performance, (2) unit time (The number of received transmission / reception bytes) as a list (step S22), and referring to the list, based on the required throughput stored in the throughput storage unit 79, the radio base station having the optimum load status for the own station 1 is selected (step S23).

  Thereafter, connection with the selected radio base station 1 is performed (step S24). When the connection is successful (YES in step S25), communication is started (step S27), but connection fails. In the case of NO determination in step S25, the next candidate is selected from the list (step S26), and connection with the radio base station is performed (step S24).

  For example, in the case of a terminal station 2 that requires high throughput due to the use of a network drive or the like, a terminal station that requests a high load by selecting and connecting the radio base station 1 with a small number of connected terminals with high load (1) 2) Mitigating transmission line conflicts between two. On the other hand, for a terminal station 2 that does not necessarily require high throughput (a terminal station 2 that only transmits and receives e-mails and texts), (2) the radio base station 1 with a large number of transmitted / received bytes (that is, a high By selecting and connecting a wireless base station 1) with a small number of connected terminals, the throughput of the entire wireless LAN 10 is improved.

  After the wireless base station 1 and the terminal station 2 are connected as described above and the actual communication is started, for example, the load status of the wireless LAN 10 managed by the wireless base station 1 (the number of collision / contention occurrences per unit time) Etc.), or the usage of the terminal station 2 is changed and the required throughput changes during the communication, so that the wireless base station 1 connected to the terminal station 2 is requested from the terminal station 2 The throughput may not be satisfied.

  In such a case, in this embodiment, the probe transmission is restarted again, and the procedure shown in FIG. 8 is performed to automatically select / change and reconnect the radio base station 1 in the optimum load state. As a result, the throughput required by the local station can be acquired every time the load status or required throughput changes, and unnecessary throughput can be released when a large amount of throughput is no longer required.

  Therefore, when there are a plurality of radio base stations 1 that can be connected to the terminal station 2 as shown in FIG. 3, the terminal station 2 is required by the terminal station 2 among the radio base stations 1 that have transmitted the load status. Since the wireless base station 1 that can provide the required throughput is selected and connected, the required throughput can be ensured and appropriate load distribution can be realized, and the overall throughput of the wireless LAN 10 can be greatly improved. Efficient system operation becomes possible.

[4] CW value changing operation In this embodiment, the CW value changing operation of this item [4] and the RTS / CTS addition & maximum packet length changing operation of item [5] described later are used in a single wireless LAN 10. The maximum throughput is ensured.
First, the CW value changing operation in the radio base station 1 of the present embodiment will be described with reference to the flowchart shown in FIG. 9 (steps S31 to S38).

  In the wireless base station 1 of this embodiment, during the operation, the number of transmitted / received bytes per unit time in the wireless base station 1 is counted by the transmitted / received byte number counter 63 (step S31). The number of retransmissions per unit time (the number of collision occurrences) for each terminal station 2 from the station 1 is counted (step S32), and the number of frame retransmissions from the terminal station 2 (the terminal station 2 retransmits) by the terminal station retransmission number counter 65. (The notification is made to the radio base station 1 by setting the retransmission number information in the frame) (step S33).

Then, the CW value setting unit 67 determines whether or not the transmission path is congested based on the count values obtained by these counters 63 to 65, and changes the setting of the CW value.
That is, first, it is determined whether or not the number of retransmissions counted by the retransmission number counter 64 exceeds a threshold value (step S34), and if it exceeds (in the case of YES determination), the CW value is greatly changed. The change of the CW value is notified to the terminal station 2 by a synchronization frame signal (step S35).

  If the number of retransmissions does not exceed the threshold (NO in step S34), it is determined whether or not the number of retransmissions from the terminal station 2 exceeds the threshold (step S36). (In the case of YES determination), the CW value is greatly changed, and the change of the CW value is notified to the terminal station 2 by a synchronization frame signal (step S35).

  When the number of retransmissions from the terminal station 2 does not exceed the threshold value (in the case of NO determination in step S36), it is determined whether the number of transmitted / received bytes is smaller than the threshold value (step S37) If it is smaller than the threshold value (in the case of YES determination), it is determined that the transmission path is not congested, the CW value is set to a smaller value, and the change of the CW value is made to the terminal station 2 by the synchronization frame signal Notification is made (step S38). If NO in step S37 (if the number of transmitted / received bytes is greater than or equal to the threshold value), the process ends without changing the CW value.

  By repeatedly performing the above processing, if the CW value setting unit 67 determines that the transmission path is congested, the initial value of CW corresponding to the back-off time set at the time of data retransmission is increased. In addition, each terminal station 2 is notified by a synchronous frame signal that is periodically transmitted. Thereby, the collision occurrence probability of the frame is reduced, and the reduced throughput can be improved. Thereafter, the number of transmitted / received bytes and the number of retransmissions are monitored, and when it is determined that the transmission path has become free (when YES is determined in step S37), the average frame interval is shortened by returning the CW value to the original value. The initial throughput can be recovered.

In this way, by dynamically changing the CW value according to the number of transmitted / received bytes, the number of retransmissions, etc., it is possible to set a frame interval with less collisions and enable efficient data transmission / reception corresponding to the load situation Thus, the throughput of the operating wireless LAN 10 can be maximized.
[5] RTS / CTS addition & maximum packet length changing operation The RTS / CTS addition & maximum packet length changing operation in the radio base station 1 of the present embodiment will be described with reference to the flowchart (steps S41 to S52) shown in FIG. .

  Similar to the CW value changing operation described above with reference to FIG. 9, the RTS / CTS addition & maximum packet length setting unit 68 of this embodiment performs RTS during frame transmission according to the degree of load (retransmission / number of received frames). / CTS frame addition state and maximum packet length are dynamically changed to adjust the loss at the time of collision and the loss of RTS / CTS frame length to ensure maximum throughput in a single wireless LAN 10 is doing.

  That is, as shown in FIG. 10, the RTS / CTS addition & maximum packet length setting unit 68 first determines whether or not retransmission has occurred by the retransmission counter 64 and the terminal station retransmission counter 65 (step S41). ), If it has occurred (in the case of YES determination), it is determined whether or not an RTS / CTS frame is currently added during frame transmission (step S42).

  When the RTS / CTS frame is not used (NO determination at step S42), the average data frame length is counted by the counter 66 (step S43), the average data frame length, the retransmission number counter 64, and the terminal station retransmission. The retransmission occurrence rate obtained from the count result of the number counter 65 is determined (step S44), and it is determined whether it is better to perform frame transmission using the RTS / CTS frame (step S45).

  In this step S45, based on the retransmission occurrence rate and the average data frame length, it is determined whether the transmission performance is better when the RTS / CTS frame is added at the time of frame transmission or not, and the RTS / CTS is improved. Frame use / non-use is determined. The criteria for judging the transmission performance will be described with reference to FIG.

  FIG. 11 shows the relationship between the presence / absence of an RTS / CTS frame and the transmission data length. In FIG. 11, T1 is an RTS / CTS frame exchange time, T2 is a data frame (DATA) transmission time, and RTS. Corresponds to the collision detection time when the / CTS frame is not used. T3 is a collision detection time when the RTS / CTS frame is used. SIFS is a short interframe space, and ACK is a reception confirmation notification signal.

If the number of collision occurrences when transmitting one frame as shown in FIG. 11 is N, the average time required for transmitting one frame when the RTS / CTS frame is not used is (N + 1) × T2, and RTS / CTS. The average time required to transmit one frame at the time of use is N × T3 + (T1 + T2).
Therefore, when the transmission performance is better when the RTS / CTS frame is used when the number of retransmissions is N times for transmission of one frame,
N × T3 + (T1 + T2) <(N + 1) × T2
At the time
(T2-T3) × N> T1
This is the case. However, T1 and T3 are fixed values.

If it is determined that it is better to use the RTS / CTS frame in step S45 based on the above-described determination criteria (in the case of YES determination), the RTS / CTS frame is used at the time of data transmission, and this is synchronized. Each terminal station 2 is notified by a frame signal (step S46).
If it is determined in step S45 that it is better not to use the RTS / CTS frame (in the case of NO determination), it is determined whether data is currently being transmitted while being fragmented (step S47), and fragmented. If this is the case (YES determination), it is determined whether it is better to increase the maximum packet length and use the RTS / CTS frame (step S48).

If YES is determined in step S48, the maximum packet length is greatly changed and the RTS / CTS frame is used, and this is notified to each terminal station 2 by a synchronization frame signal (step S49).
If NO is determined in step S47 or S48, the RTS / CTS frame is not used at the time of data transmission, and this is notified to each terminal station 2 by a synchronization frame signal (step S50).

  On the other hand, if it is determined in step S41 that retransmission has not occurred (NO determination), the process proceeds to step S47 described above. If it is determined in step S42 that the RTS / CTS frame is used (YES determination), it is determined whether data is being transmitted while being fragmented (step S51).

  If it is determined in step S51 that the data is being transmitted while being fragmented (in the case of YES determination), the processing is terminated as it is without being changed. If it is determined in step S51 that the data is not transmitted while being fragmented (in the case of NO determination), the maximum packet length is reduced, and this is notified to each terminal station 2 by a synchronization frame signal. (Step S52).

  Thus, in this embodiment, based on the retransmission occurrence rate and the average data frame length, the use / non-use of the RTS / CTS frame and the maximum packet length are determined and dynamically changed so as to improve the transmission performance. Therefore, efficient data transmission / reception corresponding to the load situation is possible, and the throughput of the operating wireless LAN 10 can be maximized.

  In the above-described embodiment, the case where the wireless communication network is a wireless LAN has been described. However, the present invention is not limited to this, and is similarly applied to other wireless communication networks. The same effect as the form can be obtained.

It is a block diagram which shows the functional structure of the base station apparatus (radio base station) for radio | wireless communication networks as one Embodiment of this invention. It is a block diagram which shows the functional structure of the radio | wireless terminal apparatus (terminal station) as one Embodiment of this invention. It is a block diagram which shows several wireless LAN with which a wireless area mutually overlaps. It is a block diagram which shows the hardware constitutions of the wireless base station in this embodiment. It is a block diagram which shows the hardware constitutions of the wireless LAN card (wireless base station and the wireless communication part of a terminal station) in this embodiment. It is a flowchart for demonstrating operation | movement (hopping pattern / timing determination operation | movement) of the wireless base station of this embodiment. It is a flowchart for demonstrating operation | movement (hopping timing correction | amendment operation | movement) of the wireless base station of this embodiment. It is a flowchart for demonstrating operation | movement (radio base station selection operation | movement) of the terminal station of this embodiment. It is a flowchart for demonstrating operation | movement (CW value change operation | movement) of the wireless base station of this embodiment. It is a flowchart for demonstrating operation | movement (RTS / CTS addition & maximum packet length change operation) of the radio base station of this embodiment. It is a figure for demonstrating operation | movement (RTS / CTS addition determination reference | standard) of the radio base station of this embodiment. It is a block diagram which shows the communication system to which wireless LAN is applied. It is a figure for demonstrating a spread spectrum system. It is a block diagram which shows the example of several wireless LAN with which a wireless area mutually overlaps.

Explanation of symbols

1 Wireless base station (Base station device for wireless communication network)
2 Terminal station (wireless terminal equipment)
3 Wireless area 4 Wired network 10 Wireless LAN (wireless communication network)
20 storage unit 21, 32 MPU
22 PCMCIA controller 23, 23A Wireless LAN card 24 LAN controller 25 SRAM
26,33 FLASH ROM
27,34 DRAM
28 EPROM
29, 30 Bus 31 PCMCIA interface 35, 36 LSI
35a MAC control unit 35b timer 35c serial interface 35d first physical layer control unit (PHY control unit)
36a Second physical layer control unit (PHY control unit)
37 Transmission / reception unit 38 Antenna 50 Frequency hopping control unit (FH control unit)
50a Search unit 50b Frequency hopping selection / setting unit 50c Timer 50d Timing adjustment unit 51 Synchronization frame transmission processing unit 52 Data transmission processing unit 53 Data reception processing unit 54 ACK transmission / reception unit 55 RTS transmission / reception unit 56 CTS transmission / reception unit 57 Probe signal transmission processing unit 58 Probe response reception processing unit 59 Synchronization frame reception processing unit 60 Probe signal reception processing unit 61 Probe response transmission processing unit (load status transmission unit)
62 Load status setting section (load status transmission section)
63 Send / receive byte count counter (load status detector)
64 Retransmission counter (load status detection unit)
65 Terminal station retransmission counter (load status detection unit)
66 Average data frame length counter 67 CW value setting section (change section)
68 RTS / CTS addition & maximum packet length setting part (change part)
Reference Signs List 70 synchronization frame reception processing unit 71 synchronization frame analysis processing unit 72 data transmission processing unit 73 data reception processing unit 74 ACK transmission / reception unit 75 RTS transmission / reception unit 76 CTS transmission / reception unit 77 probe signal transmission processing unit 78 probe response reception processing unit 79 throughput storage unit 80 Base station selector (base station device selector)

Claims (6)

  1. A wireless communication network system comprising a plurality of base station devices having wireless areas that are close to or overlapping with each other and one or more wireless terminal devices that perform wireless communication with any one of the plurality of base station devices. There,
    Each of the plurality of base station devices includes a load status transmission unit that returns a load status of each base station device to the radio terminal device as a probe response when receiving a probe signal from the radio terminal device,
    In the wireless terminal device,
    A throughput storage unit that stores the necessary throughput given in advance as information;
    A probe signal transmission unit for transmitting the probe signal to search for base station devices existing in the vicinity;
    A probe response receiving unit that receives a probe response set with a load status sent back from the base station apparatus in response to the probe signal transmitted by the probe signal transmitting unit ;
    Base station apparatus selection that selects and connects a base station apparatus having an optimal load condition based on the load condition in the probe response received by the probe response receiver and the throughput stored in the throughput storage unit A wireless communication network system characterized by comprising a part.
  2.   When the load status of the base station device connected to the wireless terminal device is not suitable for the throughput stored in the throughput storage unit, the base station device selection unit displays the probe signal transmission unit. Based on the load status sent back from the base station device in response to the probe signal transmitted by and the throughput stored in the throughput storage unit, the base station device in the optimum load status is selected / changed The wireless communication network system according to claim 1, wherein the wireless communication network system is reconnected.
  3. A wireless terminal device that performs wireless communication with any one of a plurality of base station devices having wireless areas that are close to or overlap each other,
    A throughput storage unit that stores the necessary throughput given in advance as information;
    A probe signal transmission unit for transmitting a probe signal to search for base station devices existing in the vicinity;
    A probe response receiving unit that receives a probe response set with a load status sent back from the base station apparatus in response to the probe signal transmitted by the probe signal transmitting unit ;
    Base station apparatus selection that selects and connects a base station apparatus having an optimal load condition based on the load condition in the probe response received by the probe response receiver and the throughput stored in the throughput storage unit A wireless terminal device characterized by comprising:
  4.   When the load status of the connected base station device is not suitable for the throughput stored in the throughput storage unit, the base station device selection unit transmits the probe signal transmission unit Based on the load status sent back from the base station device in response to the probe signal and the throughput stored in the throughput storage unit, the base station device in the optimum load status is selected, changed, and reconnected. The wireless terminal device according to claim 3, wherein:
  5. Communication in a wireless communication network comprising a plurality of base station devices having wireless areas that are close to or overlapping with each other and one or more wireless terminal devices that perform wireless communication with any one of the plurality of base station devices A control method,
    The required throughput is given to the wireless terminal device as information in advance,
    From the wireless terminal device, a probe signal is transmitted to search for a base station device existing in the vicinity,
    The load status is transmitted from the base station apparatus that has received the probe signal to the wireless terminal apparatus,
    Radio communication characterized by selecting a base station device having an optimum load status based on the load status sent back from the base station device and the throughput given in advance and connecting to the radio terminal device Network communication control method.
  6.   When the load state of the base station device connected to the wireless terminal device is not suitable for the throughput given in advance, the probe is sent from the wireless terminal device to the base station device existing in the vicinity. A signal is transmitted, and based on the load status sent back from the base station device according to the probe signal and the throughput, the base station device in the optimum load status is selected and changed to connect to the radio terminal device 6. The communication control method for a wireless communication network according to claim 5, wherein the communication control method is performed again.
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