Radio equipment and radio network

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to wireless networks, especially self-employed wireless networks used in homes, schools, offices and the like.

【0002】

[Previous technology]

IEEE 802.11 wireless LAN is a representative of self-employed wireless networks. As shown in the standard, the frequency band for wireless LAN is divided into a plurality of channels, and the wireless LAN operates using one of the multiple channels. For example, in the case of the 100MHz band from 5.15GHz to 5.25GHz, it is divided into 4 channels 1 to 4 shown in Fig. 13 in Japan, and it is stipulated that one of these channels should be selected and used. .. The IEEE802.11 wireless LAN access method will be described with reference to FIGS. 2 and 3.

【0003】

In FIG. 2, 1 has a master station called an access point (hereinafter abbreviated as AP) which is the center of wireless LAN, and is composed of a plurality of stations 2 to 6 (ST1 to ST5) which are slave stations. The circles in the figure indicate the reach of radio waves from the AP.

【0004】

In FIG. 3, AP1 transmits a special packet 7 called a beacon frame at a fixed cycle represented by the beacon cycle (TBCN). The beacon has a function of notifying the existence of the AP to the entire area of the wireless LAN and a function of being a starting point of PCF communication. In IEEE802.11 wireless LAN, there are two communication modes: centralized management communication mode (hereinafter referred to as PCF mode; PCF: Point Coordination Function) and distributed management communication mode (hereinafter referred to as DCF mode; DCF: Distributed coordination Function). ..

【0005】

The PCF mode is a mode in which the access right of the wireless transmission medium is arbitrated in a concentrated manner, and the AP realizes the arbitration function. Specifically, AP1 sets a parameter called NAV (Network Allocation Vector) in the beacon and transmits it.

【0006】

This value indicates the period during which the PCF continues after the beacon in the wireless LAN managed by AP1, and usually the maximum value is set within the parameter settable range (a period longer than the actual period is set) for transmission. To do.

【0007】

When the receiving station receives the NAV value of the beacon frame, it determines that the wireless transmission medium is busy during this period (the state used for other STs), and stops the carrier-sense transmission function (DCF) described later. Let me. As a result, each station 2 to 6 cannot transmit unless instructed by AP or others. In this PCF mode, AP1 polls ST1 in FIG. 2 (same number in FIGS. 2 and 3), and if ST1 has a transmission packet 9, transmits it. When AP1 receives a packet destined for ST2 from ST1, it adds this packet 11 to polling packet 10 and sends it when polling ST2.

【0008】

In this way, in PCF, communication between STs is realized not by arbitration between STs but by the intervention of AP. This PCF period ends when AP1 sends a command packet (PCFend) 12 at the end of the PCF period and each station ST1 to 5 receives it.

【0009】

In this example, communication by polling is shown, but TDMA also allows each ST to access the wireless transmission medium without arbitration between STs, which makes it possible to realize PCF communication. PCF communication is suitable for isochronous data communication such as voice and video because the access right to the medium is given to each station in the beacon cycle and the arrival delay time of the packet can be limited within a certain value.

【0010】

The DCF independently detects the carrier of the wireless transmission medium (channel), and if it determines that the transmission medium is not used, each ST independently transmits (distributes and mediates access rights). ) Method, which is typically called CSMA / CA (carrier Sense Multiple Access with collision avoidance).

【0011】

The DCF period is assigned to the Beacon cycle (TBCN) other than the PCF period. In the DCF mode, each ST can transmit without waiting for polling from AP1, and packets 13 and 14 in FIGS. 2 and 3 are DCF communication between ST3 and ST4. Packet arrival at this mode destination can be realized quickly. In addition, it is a method suitable for accommodating burst traffic in which data is not generated at regular intervals.

【0012】

Furthermore, a gateway function is required for the wireless LAN to connect to the external public network / service such as the Internet, but it is usually realized by the same device as the AP shown in 1 in Fig. 2.

【0013】

[Problems to be Solved by the Invention]

Wireless LAN operates using one of multiple wireless channels, but the method of channel selection has not been clearly defined.

【0014】

For this reason, when wireless LAN becomes widespread as a home wireless network, the number of wireless channels that can be used is limited, so there is a possibility that the wireless LANs of adjacent homes will randomly select the same channel without mutual arbitration. In this case, the wireless LAN station has a problem that communication failure frequently occurs due to interference. Especially when the PCF mode operates, relatively long contents such as movies are transmitted at regular intervals, so there is the inconvenience that PCF communication cannot be performed due to interference caused by operating the PCF asynchronously on the adjacent wireless LAN. It was.

【0015】

Further, when a plurality of wireless LANs exist over a wide area, the frequency channels used by each wireless LAN are not optimally arranged, so that there is a problem that the number of wireless LANs that can be accommodated in a certain number of channels is reduced.

【0016】

An object of the present invention is to reduce interference in a wireless LAN and to increase the number of accommodated wireless LANs in a constant number of wireless channels.

【0017】

[Means for solving problems]

In the wireless LAN of the present invention, the AP that controls each station monitors the usage status of all wireless channels for a certain period of time, selects the most suitable free channel for use, and further, of all wireless channels that can be used regularly. It is a wireless network that monitors the communication environment and controls to reselect wireless channels if necessary, and can reduce the probability of overlapping channels used between neighboring households.

【0018】

Furthermore, if there is no free wireless channel at startup, the AP operates as a slave AP under the umbrella of this AP to other APs with the lightest load and good reception signal condition among the wireless channels, and wireless LAN. It is a wireless network that controls the PCF period so that it operates by arranging each other, and it is possible to increase the number of accommodated wireless LANs in a certain number of wireless channels.

【0019】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described.

【0020】

Figure 1 shows the configuration of the wireless LAN master station (AP) according to the present invention. In the figure, 86 is an antenna, 71 is a radio unit, and the radio unit 72 selects a channel (frequency) and converts it to an IF frequency in the radio unit 72, and the modulation / demodulation unit 73 converts it into a baseband signal. It is input to the MAC unit 73. The MAC unit has a packet identification and reception function, and stores received data in the memory 74 via the internal bus 76.

【0021】

Transmission operates in the reverse procedure, and the transmission data stored in the memory unit 74 is packetized by the MAC unit 73, and if it is determined that the transmission path can be transmitted, it goes through the modulation / demodulation unit 72, the radio unit 71, and the antenna 86. And is transmitted to the transmission medium (space).

【0022】

The control unit 75 controls each unit in the ST, activates the transmission / reception of packets, and transfers data to the outside via the external interface 77.

【0023】

83 has a function to measure the electric field strength, 84 has a function to measure the bit error rate in the channel selected by the radio part, and 85 has a function to measure the packet traffic amount (channel load factor) in the selected channel, and these measurement results. The control unit 75 obtains free channel determination information from.

【0024】

When the reception strength of the measured radio channel is equal to or less than a certain value, the control unit 75 determines this as a free channel and selects one of the free channels as the channel to be used.

【0025】

If there are no free channels, search for another master station with good channel signal quality (low bit error rate) and light packet traffic (channel load factor) on the channel, and use the same channel as this master station. To use.

【0026】

FIG. 4 is a configuration example of a wireless network to which the present invention is applied (hereinafter referred to as a wireless LAN). It is assumed that the houses are densely packed and each household has its own wireless LAN. Each home has a wireless LAN slave station (station: ST) that performs data communication, and a master station (access points: AP15 to 22) that realizes communication between STs and communication functions outside the home.

【0027】

Now, it is considered that the usable channels of the wireless LAN are the four channels (CH0, CH1, CH2, CH3 and CH4) shown in FIG. Covering a certain area with multiple radio channels is the same as the map coloring problem in mathematics, and it has been proven that four colors can be painted in adjacent areas without using the same color. Therefore, it would be good if there were 4 channels. However, this is a case where strict frequency management is performed like a public cellular telephone, and it is difficult to arrange the optimum frequency in a wireless LAN that is premised on self-employment.

【0028】

Now, for AP15 installed in the shaded home in Fig. 4, CH4 must be originally selected because AP16 to AP21 in the surrounding homes use wireless channels CH1, CH2, and CH3. Otherwise, the same frequency will be used between neighboring houses, and ST in a place where the same channel radio waves can be received from both the home and neighboring houses may not be able to receive data due to interference, especially in PCF communication.

【0029】

Here, according to the first invention of the present application, AP15 can autonomously select CH4. This selection method will be described with reference to the flowchart of FIG.

【0030】

As shown in FIG. 5, the electric field strength of the wireless channel and the packet load to be communicated are measured for a certain period of time from power-on or reset, and these are stored. If the electric field strength is less than or equal to the specified value, it is judged as an empty channel, and the channel number is stored together with the value of the received electric field strength.

【0031】

If an AP already exists on a channel, the beacon is received at a specific cycle, so it is easy to detect that the channel is not open.

【0032】

All wireless channels are searched, and if there is only one free channel, this is used as the wireless channel to be used. If there are multiple access channels, select one by some criteria (for example, the number of free channel numbers is small, large, or determined by a random number). In the case of FIG. 4, AP15 detects that CH1 to CH3 are used by the operation based on the flow of FIG. 5, and autonomously selects CH4. A free channel may not be found, but the processing in that case will be described later.

【0033】

When a free channel is found, the AP transitions to the beacon frame transmission process shown in FIG. In order to send out the beacon periodically, the beacon timer that ticks the cycle is initialized, the necessary information is stored in the beacon frame, and the beacon is sent out. In the case of a method such as IEEE 802.11 that determines the packet transmission opportunity by carrier sense, it is confirmed that there is no carrier before transmission. Further, in the present invention, there is a parameter called a monitoring interval counter, and a special beacon called a monitoring start beacon is transmitted once every few times of normal beacon transmission. This beacon has its own AP because it enters PCF mode during the period indicated by the NAV parameter (Network allocation vector: the receiving ST determines that the transmission medium is in use for this parameter time and does not transmit packets) for each ST. The managed ST does not send. Received field strength and packet error rate for all radio channels during this period. Contains instructions to monitor the communication load.

【0034】

As a result, each ST monitors the reception environment of all channels around its own ST after receiving the monitoring start beacon.

【0035】

The initial procedure on the ST side will be described using the flowchart of FIG. The upper side is a normal initialization operation, and after the power is turned on or reset, it is checked whether the beacon frame can be received for all channels and the network identifier is the same. Here, the network identifier is an identifier indicating whether or not to operate as a single wireless LAN under the same administrator, and wireless LAN devices having the same identifier constitute the same wireless LAN system.

【0036】

When a beacon with the same wireless network identifier (called an ESS identifier in the IEEE 802.11 standard) is received, the received wireless channel is determined to be the channel to be used in the future, and parameters such as the predetermined transmission power existing in the beacon are used. Receive and set the operating conditions of your own station. If the beacon is not received even after inspecting all channels, it is determined that the AP does not exist and the user is notified to that effect. (Alternatively, if a mode that operates without an AP (ad hoc mode) can be operated, it is possible to transition to that mode, but since it is not directly related to the present application, it is not described here).

【0037】

Further, the operation of each ST with respect to the monitoring beacon mode described in FIG. 5 will be described at the lower side of FIG. Even in ST during normal operation, each time a beacon is received, it is determined whether the monitoring beacon has the same identifier as the own network identifier. If the monitoring beacon meets the conditions, transmission is stopped only for the period indicated by the NAV parameter in the beacon (or until the end command of the PCF period is received from the AP) as in the normal PCF mode.

【0038】

During this period, all the AP-participating STs that sent out the surveillance beacon have stopped transmitting, so the received radio waves are not from the own wireless LAN but from other APs and STs. For all wireless channels, data on the received electric field strength and packet load status is collected, accumulated, and notified to the AP. In the figure, it is described that the AP is notified each time, but it may be once for several monitoring beacons, and the transmission timing may be arbitrary.

【0039】

In addition, since packet load information and the like need to be observed for a considerably long period of time, they may be monitored over several monitoring beacons. Here, the reason why all STs monitor the interference radio waves from the adjacent AP is that some STs are located near the AP of the neighboring house, which is the interference source, and some are not. This is because it is often not possible to grasp the relationship in advance.

【0040】

If it is determined that the radio channel used should be changed based on the interference situation, the AP notified of the monitoring result from ST to the monitoring beacon selects a new radio channel according to the operation flow shown in FIG.

【0041】

The state of the surveillance beacon will be described with reference to FIG. In the wireless LAN, the AP ((1) in the figure) periodically transmits the beacon frame 23 and the monitoring beacon 24 at a longer cycle. The ST that received the surveillance beacon ((2) in the figure) transmits it for a certain period of time (25 in the figure). During this period, ST will start monitoring the radio wave condition, but if there is interference from AP and ST of other wireless LANs shown in 26 ((3) and (4) in the figure), record this received electric field strength, etc. It notifies the AP. Monitor all radio channels, not just the same radio channel.

【0042】

According to the present invention of claims 1 and 2, when the power of the AP is turned on, the radio channel determined to be optimal only by the AP is also reviewed by all STs at regular intervals, and the truly optimal wireless channel can be selected. It will be possible.

【0043】

Next, the case where there is no free channel at the time of starting the AP corresponding to claim 3 of the present application will be described with reference to FIGS. 8 and 9.

【0044】

Figure 1 shows the configuration of the wireless LAN master station (AP) according to the present invention. In the figure, 86 is an antenna and 71 is a radio unit. The received signal is converted into a baseband signal by the modulation / demodulation unit 72 and input to the MAC unit 73.

【0045】

The MAC unit 73 has a packet identification and reception function, and stores received data in the memory 74 via the internal bus 76. Transmission operates in the reverse procedure, and the transmission data stored in the memory unit 71 is packetized by the MAC unit 73, and if it is determined that the transmission path can be transmitted, it goes through the modulation / demodulation unit 72, the radio unit 71, and the antenna 86. And is transmitted to the transmission medium (space).

【0046】

The control unit 75 controls each unit in the ST, activates the transmission / reception of packets, and transfers data to the outside via the external interface 77. The above is the same function as ST.

【0047】

Reference numeral 78 in the figure is a beacon generation unit, which periodically transmits a beacon as an AP when the bicon cycle timer (TBCN timer) 79 expires. The AP manages the centralized management communication mode (PCF) period, but the TPCF timer 80 operates after the beacon is transmitted, and when the PCF period expires, the PCFend command is transmitted via the PCFend generator 82. As a result, the end of the PCF period is notified to all STs under AP control.

【0048】

In the master / slave AP mode, information on the PCF period required by each wireless LAN is exchanged between the master AP and the slave AP, and a new PCF period is calculated. Each AP has this value, sets the value in 80 TPCF timers in the figure, and manages the new PCF period. Each AP controls the PCF period such as polling so that the PCF periods do not overlap (for example, the master AP uses the PCF period first).

【0049】

Reference numeral 82 in the figure is a folded portion of the beacon / PC Fend according to the present invention, and is activated only when the AP is set as the slave AP. When the PCF period start beacon is received from the master AP, the slave master station also immediately transmits a beacon having the same value of the PCF period by this part. When PCFend arrives, it will be broadcast from the slave AP as well. As a result, the PCF period is notified to all STs in the reception range of the master AP radio wave and all STs in the reception range of the slave AP radio wave. Wireless LAN interference is eliminated.

【0050】

In addition, even if the beacon from the master and PCFend do not arrive normally at the beacon / PCFend return section due to a transmission error, the PCF period can be terminated by the uniquely owned 78 to 81 beacons and PCFend transmission function. Safety is improved without accidentally occupying the transmission medium.

【0051】

The functions 78 to 82 can be realized not only by hardware but also by software.

【0052】

The upper part of Fig. 8 shows the case where wireless LAN is installed in a densely populated private house as in Fig. 4, and the part shown by the hexagon has already been optimally assigned the frequency using the radio waves of CH1 to CH4. And. Consider the case where it becomes necessary to newly place an access point in the part indicated by the shaded circle in the figure in this state.

【0053】

In this case, AP27 operates according to the AP initialization procedure shown in Fig. 5, but the channel used by the existing wireless LAN is used because the usage status of all channels is monitored and it is found that there is no free channel. Attempt to participate (hang) in. In the lower part of FIG. 8, AP27 operates as a slave AP of another AP28 (referred to as master AP) and uses the same radio channel (CH4) as the master AP.

【0054】

Here, as explained in the section of the problem, if the same radio channel is simply used without arbitration, interference occurs and communication becomes impossible in the PCF mode. Therefore, when using the same wireless channel, arbitration (separation) on the time axis of PCF mode is required, and the state of the linked wireless LAN after arbitration is called the hanging mode (this is called the hanging mode). This name is used because a new wireless LAN "hangs" from an existing wireless LAN).

【0055】

The operation of the AP is shown in the flowchart of FIG.

【0056】

The AP first determines whether or not to make a hanging mode transition by a flag set by the user, and if the transition to the mode is prohibited, notifies the user that there is no free channel and ends the operation. To do.

【0057】

If the hanging mode is allowed, for APs whose received electric field strength is equal to or higher than a preset constant value and the network load is lighter than a certain value among the reception states of each channel determined by the search for free channels. Then, a hanging request packet including its own address and network identifier is transmitted to the AP of the channel. When an authorization response packet is received from the destination AP, the AP transitions to the slave AP.

【0058】

When a reject response is received, a hanging request is issued to other APs that meet the conditions. If all are rejected, the AP will notify the user of this and stop the operation.

【0059】

Here, the slave AP needs to adjust and manage (separate) the transmission medium usage time in the PCF mode for the (master) AP that is already using the same wireless LAN channel.

【0060】

The segregation operation of the PCF will be described with reference to the lower side of FIG. 9 and FIG. In Fig. 8, the slave AP and master AP that performed affirmative communication for the hanging request exchange parameters such as the beacon cycle (TBCN) and PCF period (TPCF) required for the own wireless LAN for the segregated PCF mode. Then, the master AP (strictly which AP is in charge of it is possible) calculates a new beacon cycle and PCF period. Normally, the new PCF period is the sum of the PCF periods requested by both APs. After exchanging the parameters, the AP will be in the master and slave modes of the segregated PCF, and the operation at this time will be described with reference to FIG.

【0061】

In Fig. 10 (1), 29 is the master AP, 30 is the slave AP, and 31 and 32 are ST1 and ST2 under AP29. 33 and 34 are ST3 and ST4 under the umbrella of AP30.

【0062】

Assuming that the required PCF period of the wireless LAN managed by AP29 is TPCF29 and the required PCF period of the wireless LAN managed by AP30 is TPCF30 according to the procedure shown in Fig. 9, the new PCF cycle (new TPCF) and beacon cycle (TBCN) The relationship between the parameters is as shown in Fig. 10 (2). As soon as the master AP29 sends the beacon frame BCN29 with the NAV set appropriately, the AP30 gives the timing to send the beacon.

【0063】

AP30 immediately sends a beacon frame BCN30 with the same NAV. After this, AP29 immediately polls the ST under its own wireless LAN during the period of TPCF29, does not communicate during the period of TPCF30, and transfers the right to AP30 (shown by the wavy line in the figure). Similarly, AP30 does not communicate during the period of TPCF29, but communicates by polling its affiliated ST during the period of TPCF30.

【0064】

When the new TPCF time ends, AP29 sends the PCF period end command PCFend29, and AP30 also immediately sends PCFend30 to exit the segregation PCF mode. When AP29 transmits the beacon BCN29, ST33 is under the umbrella of AP30 and is in a position where it cannot receive the signal from AP29, so it cannot receive BCN29.

【0065】

Although ST33 does not recognize that the PCF period starts at this point, it becomes possible to recognize the existence of the PCF period by receiving the beacon BCN30 from the AP30 immediately afterwards. The same applies to the reception of the PCF end command. This makes it possible to notify all STs under the control of both APs of the separate PCF period, eliminating problems such as accidental transmission in DCF mode and overlapping PCF periods, ensuring stable communication. It will be possible. Here, the beacon of the master AP and the PCF end command precede that of the slave AP, but the same effect can be obtained in the opposite case.

【0066】

In the explanation, the case where two wireless LANs share the same wireless channel is shown, but a configuration in which there are multiple slave APs for one master AP, and three or more wireless LANs are connected in tandem with subordinate completion. Configuration is also possible.

【0067】

In addition, although the PCF period may be fixed, it is conceivable that connections with long connection times such as video transmission will be added or deleted. In this case, when creating / deleting a connection, the transmission medium can be used more efficiently by exchanging information on individual TPCF periods between APs and readjusting the entire TCF period. Since TV programs have a long connection time, the overhead due to TCF readjustment is negligibly small.

【0068】

In the invention by the applicants of the present application (Japanese Patent Laid-Open No. 11-219737), a method of mediating (separating) the PCF periods of a plurality of wireless LANs is described, but a plurality of APs sharing the PCF mode. Even if communication is not possible for all STs on the wireless LAN (hidden terminal state), according to this application, all APs will be notified of the arbitrated PCF period, and all STs will be notified of the PCF period. Wireless LAN can operate stably without misunderstanding ST.

【0069】

Further, according to the invention of claim 4, even when ST1 in FIG. 10 communicates with ST3 in 33, AP29 and AP30 are in a relationship of being able to communicate with each other, so that the AP30 sends the packet 35 in response to the polling of AP29. It is possible to receive and relay packet 36 to 33 ST3s at the AP30 polling opportunity. Even in the DCF period other than the PCF period, AP29 and AP30 receive the packet of ST under the other AP as a bridge, and if it is ST under its own station, it can be relayed to enable mutual communication between STs. ..

【0070】

The wireless LAN initialization procedure described above is that it is unlikely that the channel used will change each time, that the radio wave environment does not change frequently, especially for home use, and that even if it changes, radio waves will be generated regularly. Since the present invention for monitoring the environment can be used, as described in claim 5, the radio channel information once set is stored in the non-volatile storage element of the AP, and this value is used when the power is started. The initialization time is shortened by starting up, and since ST controls to automatically follow the channel selection of AP, ST itself does not have a memory.

【0071】

In the case of a composite wireless LAN in which wireless LANs using the same channel described with reference to FIGS. 9 and 10 are combined, there are two possible ways to realize this, depending on the concept of authentication and management.

【0072】

First, as described in claim 7, the master and slave APs and all STs have the same network identifier (equivalent to BSS-ID in IEEE 802.11), and the APs are considered as a single wireless LAN having a plurality of APs. .. At this time, if the owners of the original master AP and its wireless LAN, and the slave AP and its wireless LAN are different, it is necessary to maintain the confidentiality of the wireless LAN communication for each owner.

【0073】

For this reason, it is indispensable to introduce a new identifier indicating the user (holder) described in the present application, thereby ensuring confidentiality such as encryption. In addition, since the same wireless medium is shared, it is necessary to appropriately manage the usage status, and the AP manages traffic for each user identifier.

【0074】

The other method is when the master and slave wireless LANs have different network identifiers. Mutual communication in this case is realized by using the extended wireless LAN identifier (ESS-ID of IEEE 802.11), but since traffic management still needs to be performed for each user, as shown in claim 8. Traffic management is performed in the AP for each network identifier. Figure 11 shows an example of a home network using the wireless network according to claims 3 and 4.

【0075】

This is not the case when there are no free channels. When wireless LAN 36 is installed in home 35, radio waves may propagate to neighboring home 37. Normally, radio waves propagate to neighboring houses, which is a source of interference with wireless LANs that will be introduced in the future, so it is necessary to take measures to prevent this, but this is an example of actively using this. This is a case where the home 37 actively hangs the wireless LAN 36 of the home 35 and enjoys services such as the Internet from the AP39.

【0076】

The gateway (GW) function for connecting to an outside line is often implemented in the AP. In the figure, AP39 is assumed to be connected to the public Internet such as CATV, DSL, and ISDN. In the case shown in FIG. 11, the confidentiality and traffic are managed by the method described in claims 7 and 8. Furthermore, in the figure, AP39 also has a GW function including a database function for accumulating communication traffic information with an outside line for each household.

【0077】

The configuration diagram of the GW device is shown in FIG. In the figure, 42 is a wireless LAN interface unit, which receives packets from the wireless LAN. The received packet is forwarded to the relay determination unit via the internal bus 47, it is determined whether or not the packet should be relayed to the outside, and if it is a packet to be relayed, it is forwarded to the public network / Internet interface 44, and the Internet, etc. Connected to and transferred to public services. In the figure, 45 is a node processing unit that controls packet transfer within the node. The statistical information processing of the wireless LAN packet for each home according to the present invention is determined by the network identifier or the user identifier in this part, and is transferred to the traffic database unit 46.

【0078】

In FIG. 6 and the above description, it is described that AP40 exists in home 35, but it is naturally possible for ST41 and the like to directly join AP39 in home 35. In this case as well, the external line connection traffic of each household is managed by the GW according to the present invention.

【0079】

In Fig. 11, in the case where AP40 or ST41 of home 37 hangs from the wireless LAN of home 35, when receiving a paid wide area communication service such as the Internet via AP39 (which also has a GW function in this example), all home 35 It will communicate via AP39 of. The wireless LAN gateway function according to the present invention of claim 9 realizes a log function for each household, and makes it possible to split the charge for public services according to the amount of communication in each household.

【0080】

In addition, although the example in which the wireless LAN terminal of the home 37 hangs from the wireless LAN of the home 35 is shown, it is also possible that the wireless LAN terminal of another adjacent home hangs.

【0081】

As mentioned above, if the wireless LAN of the home 37 allows the wireless LAN terminals of the other home 35 to hang, and the home 37 pays the corresponding price to the home 35, the parties concerned will be able to give and receive money. If implemented directly, the procedure may be complicated and emotional problems may occur (payment delinquency, reminder, etc.). To implement a service that mediates this, and to install a wireless LAN with the functions described in this application in the form of a loan from the beginning, solicit the participation of households in the vicinity of the installation location, and collect a fixed amount of usage fee. Services and rental / maintenance services for various wireless network devices such as AP, GW and ST are also available.

【0082】

In the hanging mode, as shown in FIG. 10 (1), the APs were in a positional relationship in which they could communicate with each other. However, this positional relationship does not always hold.

【0083】

Even if the APs cannot communicate directly, the hanging mode can be realized if there is an ST53 that can communicate from both APs 51 and 52 as shown in Fig. 14 (1). In this case, ST53 is the ST of the AP51, and the ST of the AP52 is operated to mediate the communication between the AP51 and 52. This ST is called a proxy ST, and the hanging mode by this ST is referred to as the proxy hanging mode thereafter.

【0084】

Each ST can determine that proxy ST is possible by confirming packet reception from APs other than the parent station AP by monitoring the communication status of all channels using the monitoring beacon.

【0085】

The AP grasps whether or not ST exists in such a positional relationship by the monitoring beacon response, and when the proxy hanging mode is executed, the ST is designated as the proxy ST (if there are multiple STs, the reception status). Select one ST for some reason, such as who is better). In the figure, the proxy ST53 relays the packet between AP51 and AP52 to both APs and also mediates the composite PCF mode described below. ..

【0086】

The AP51 and 52 can carry out the operations and procedures of claims 3 and 4 even in the operating environment of FIG. 14 (1) due to the presence of the proxy ST. Further, as shown in FIG. 14 (2), by relaying the beacon 51 indicating the start / end of the PCF period from the master AP51 and the PCFend51 command as the proxy beacon and the proxy PCFend, the beacon 52 and the slave AP52 also operate at almost the same time. PCFend52 can be sent. As a result, even if the APs are present in the positional relationship shown in FIG. 14 (1), collision / interference during the PCF period between the APs can be avoided.

【0087】

The hanging mode (when direct communication between APs is possible) and the proxy hanging mode (when communication between APs is possible via an intermediate ST) are explained, but when communication is not possible directly between APs and via ST. , FIG. 15 (1) will be described. In the figure, AP54 and 55 cannot communicate directly, and ST56 and 57 do not exist at the proxy position.

【0088】

In the figure, the solid circle with radius L1 centered on AP is the reach range of radio waves that can send and receive data, and L2 is the range that interferes with the other party even though data cannot be sent and received. Normally, L2 >> L1 and it depends on the frequency of the radio wave used, but L2 takes about twice as much as L1.

【0089】

In the case of this figure, different channels are assigned to the AP by the method according to claim 1, but if there are no free channels, the same channel may be used. When using the same channel, ST57 and 58 in the figure are interfered by the other AP. Therefore, the interference is detected by radio wave monitoring by the monitoring beacon of the AP according to claim 2, and one of the APs uses the channel. Will be abandoned. Therefore, it is necessary to devise ways to further improve the channel usage efficiency.

【0090】

When the same channel is used with AP54 and 55 in Fig. 15 (1), in order to avoid interference due to continuous communication with a fixed cycle as in PCF mode, segregation on the time axis as explained so far. is required. However, in a self-employed wireless LAN, the AP is not always connected to a synchronization network such as ISDN as in public cellular communication.

【0091】

Therefore, in order to realize synchronization between APs, it is possible to synchronize between APs by using positioning technology such as Global Positioning System (GPS) as shown in Fig. 15 (2). In the figure, AP59 receives the signal from the GPS artificial satellite 58 with the GPS antenna 61 and obtains accurate time information. Similarly, another house's AP60 receives GPS signals via GPS repeater 62. The GPS repeater 62 is a device that retransmits GPS signals received outdoors when a GPS antenna cannot be installed.

【0092】

As a result, AP59,60 will have an accurate time. Furthermore, by accessing the network management ST63 via a public network such as the Internet and obtaining and exchanging information on the beacon cycle and PCF period, collisions can occur between the two wireless LANs in the same way as in the hanging mode shown in Fig. 10 (2). It is possible to divide and use the PCF mode without using it. As a result, wireless LAN communication is possible without interference even when direct communication between APs is not possible or when proxy ST does not exist.

【0093】

FIG. 15 (3) is an example of a GPS-compatible AP device, and the wireless LAN antenna 64, the wireless LAN interface 65, the public network interface 66, and the node processing device 67 have the same functions as those shown in FIG. These are connected by the internal bus 68. The signal received from the GPS antenna 69 has an accurate time detected in the GPS reception failure 70 and is sent to the node processing unit 67. Based on this information and the beacon cycle / PCF period information obtained via the public network, the node processing unit controls the PCF period in the wireless LAN interface.

【0094】

[Effect of the invention]

According to the present invention, it is possible to select an appropriate wireless channel in a wireless LAN installed in a home or the like.

【0095】

Furthermore, even if there is no free wireless channel, it is possible to operate as a part of another wireless LAN, so that the accommodated wireless LAN can be increased even with a small number of wireless channels.

[Simple explanation of drawings]

[Figure 1]

The figure which showed the structure of the wireless device of this invention [Figure 2]

Configuration diagram of wireless LAN to which the present invention is applied [Fig. 3]

The figure which shows the transmission signal on the wireless LAN to which this invention is applied [Fig. 4]

Wireless LAN configuration diagram for explaining the operation of the present invention [Fig. 5]

Flow chart on the master station side for explaining the operation of the present invention [Fig. 6]

Flow chart on the slave station side for explaining the operation of the present invention [Fig. 7]

Explanatory drawing of monitoring mode of this invention [Fig. 8]

Wireless LAN configuration diagram for explaining the operation of the hanging mode of the present invention. [Fig. 9]

Master station flowchart for explaining the operation of the hanging mode of the present invention. [Fig. 10]

An operation explanatory view provided for the operation explanation of the hanging mode of the present invention. [Fig. 11]

Configuration diagram of a home wireless LAN connected to the public when the present invention is applied [Fig. 12]

Configuration diagram of the wireless LAN gateway device of the present invention [Fig. 13]

Wireless LAN channel layout [Fig. 14]

An operation explanatory diagram provided for the explanation of the proxy hanging mode of the present invention. [Fig. 15]

Operational diagram of network synchronization in an independent home wireless LAN of the present invention [Explanation of symbols]

1, 15, 16, 17, 18, 19, 20, 21, 22, 27, 28, 29, 30, 39, 40 Master station (access point: AP) 2, 3, 4, 5, 6, 31, 32, 33, 34, 41 slave stations (station: ST) 7, 23 Beacon frame 8, 10 polling packets 9, 10, 13, 14 data packets 12 Centralized management communication mode end command (PCF end command) 24 Surveillance Beacon 25 Transmission prohibition period 26 Interfering radio waves 35, 37 Homes (houses) 36, 38 (for home use) Wireless LAN 42 Wifi interface 43 Relay judgment unit 44 Public / Internet Interface 45 Node control unit 46 Traffic database 47 Internal bus 51,52, 54,55, 59, 60 Master station (access point: AP) 53, 56,57 Slave stations (station: ST) 58 GPS satellites 61 GPS antenna 62 GPS repeater 63 Network management station 64 wifi antenna 65 Wifi interface 66 Public switched telephone network / Internet interface 67 Node processing unit 68 Internal bus 69 GPS antenna 70 GPS receiver 71 Wireless section 72 Modulation / demodulation section 73 MAC part 74 Memory section 75 Node control unit 76 Internal bus 77 External interface 78 Beacon generator 79 TB CN timer part 80 TPCF timer section 81 PC Fend 82 Beacon / PC Fend Wrap 83 Received electric field strength measuring unit 84 Error rate measurement unit 85 channel load measuring unit 86 antenna