JP2009296184A - Radio communication network system, access point selection program, and storage medium having access point selection program stored therein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently select an access point of the best communication quality/communication efficiency in a radio communication network system including a plurality of access points and a radio communication terminal. <P>SOLUTION: A radio network includes a plurality of radio communication access points and the radio communication terminal. When the radio communication terminal selects the access point to be connected, each access point transmits a random data packet to the radio communication terminal. The radio communication terminal measures the number of FCS errors of the received data packet by an FCS error counter block 54, compares it in an FCS error counter comparator 58, and selects the access point with the minimum number of errors to be connected. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless communication network system for selecting an access point as a communication partner from one or a plurality of wireless communication access points using a wireless LAN, an access point selection program, and a storage medium storing an access point selection program.

In recent years, wireless communication technology for building a network wirelessly rather than wired and performing data communication has been rapidly developed. Conventionally, when constructing a communication network, it has been necessary to connect communication devices using a wired LAN (local area network) cable, but it is not necessary to use a LAN cable for wireless communication. become. For this reason, the demand for wireless networks is increasing due to the inconvenience of laying cables and the beautification of office layouts.
The communication standard for the wireless LAN is defined by IEEE 802.11, and here, the wireless communication distance, the communication speed, the network construction method, and the like are defined. Unlike an ad hoc network in which wireless communication terminals are directly connected to each other, in an infrastructure network, a wireless communication terminal communicates with a wireless communication terminal to communicate with via an access point. Can be communicated with wireless communication terminals that are very far away from each other.
For this reason, it is common to build an infrastructure network in an office environment or the like, but since the spatial range in which one access point can communicate is limited, usually the spatial communication range between access points is limited. The access points are installed so that they do not create a space where wireless communication is not possible.

At this time, as shown in FIG. 1, there may be a plurality of access points with which the wireless communication terminal can communicate. In such a case, there is a method of selecting the transmission source access point having the highest signal strength by measuring the received signal strength from each access point as a method of selecting the access point that is normally performed.
However, when an access point is selected by this method, influences such as interference waves are not considered at all, and even if an access point having the highest received signal strength is selected, the data transfer rate (packet error rate: PER) is Not necessarily the smallest.
Therefore, the following proposal has been made as a method of selecting an access point of a communication partner.
JP2007-110373 JP2007-104054

In the technique described in Patent Document 1, when the access point is selected, the PER value and the interference signal strength, the interference adjacency degree, the PER value using the approximate graph obtained from the experimental data, and the access point management are used. A method is proposed in which a throughput value is measured from the number of wireless communication terminals and a communication rate, and an access point having the best throughput value is selected as a communication partner. However, in this method, complicated flow control must be performed, and a very large circuit or program must be mounted.
Although Patent Document 2 is not a document showing an access point selection method, a method of measuring a bit error rate and a packet error rate of each radio channel has been proposed as a radio channel selection method with good communication quality. However, even with this method, it is necessary to implement a circuit and device driver for each radio channel, and a radio signal reception processing unit exists for each radio channel, so a very large circuit or program is implemented. There must be.

By the way, among the conventionally proposed access point selection methods, the method of measuring and selecting the received signal strength does not always have good transfer efficiency as described above. In addition, the inventions described in Patent Document 1 and Patent Document 2 require very complicated flow control, and there is a problem that the implementation of a circuit or a program becomes very large.
Therefore, the present invention provides a method for a wireless communication terminal to select an access point with a good communication quality from a plurality of access points capable of communication without taking a complicated sequence with a small circuit or program implementation. The purpose is to do.

According to the first aspect of the present invention, there is provided a wireless communication network composed of a plurality of wireless communication access points and a plurality of wireless communication terminals. When the wireless communication terminal selects an access point of a communication partner, a plurality of communication points are selected. Transmission request means for requesting the access point to transmit random data packets, and reception means for receiving random data packets transmitted in order from a plurality of access points in response to a request from the transmission request means; An error number counting means for calculating the CRC32 of the data packet received by the receiving means and counting the number of FCS errors, and a transmission source access point with the smallest number of errors as counted by the error number counting means as an access point of the communication And an access point selection means for selecting a plurality of wireless communication access points. The access point includes the packet transmission unit that receives a request from the transmission request unit and transmits a random data packet, thereby achieving the object.
According to a second aspect of the invention, in the first aspect of the invention, when the transmission request means makes a random data packet transmission request to each access point, a reserved bit in the type / subtype field of the MAC header field is used. Then, an access point selection request packet that is a transmission request packet indicating a packet having a unique protocol field is transmitted to a plurality of access points simultaneously.
In the invention according to claim 3, in the invention according to claim 2, in the access point selection request packet, the unique protocol field includes a communication rate, a payload length, a number of packets, a transmission power field of a packet transmitted by each access point. The access point has a field indicating a transmission order among a plurality of access points.
According to a fourth aspect of the present invention, in the first, second, or third aspect of the invention, the order in which the packet transmitting means transmits the data packets to the wireless communication terminal is transmitted from the transmission requesting means. Access to which the wireless communication terminal transmits a reception response packet to the data packet transmitted from each access point and receives the reception response packet. When the point decrements the transmission order and the transmission order count value becomes 0, the data packet is transmitted.
According to a fifth aspect of the invention, in the first aspect of the invention, when the number of FCS errors of packets transmitted from a plurality of access points counted by the error number counting means match, the access having the maximum received signal strength The point is selected as a communication partner.
According to a sixth aspect of the present invention, in the first aspect of the present invention, the access point selection unit scans with a plurality of access points that are candidates for communication when the access point as a communication partner has not yet been selected. And the transmission request means requests to transmit a random data packet after performing authentication work with all access points to enable data communication.
According to a seventh aspect of the present invention, in the first aspect of the present invention, when the access point selecting means has selected an access point for the communication, a threshold having a FCS error count is obtained by counting by the error count counting means. When the number exceeds, the transmission request means requests a plurality of access points to transmit random data packets, and selects an access point as a communication partner again.
In the invention according to claim 8, in the invention according to any one of claims 1 to 7, when the transmission request means has a single access point for requesting transmission of a random data packet, an access is made. The point selection is not performed.
According to a ninth aspect of the invention, in the first aspect of the invention, the wireless communication terminal corresponds to a wireless communication signal processing block, an FCS (CRC32) calculation block, an FCS error count block, and a plurality of access points. A register for holding an error count, a comparator for comparing the number of FCS errors, a transmission block for transmitting an access point selection request packet and a reception response packet, and a block for measuring a received signal strength To do.
According to a tenth aspect of the present invention, in the first or ninth aspect of the invention, the access point includes a radio communication signal processing block and a received packet decoder block for determining that the received packet is an access point selection request packet. And a counter block for decrementing the transmission order counter when a reception response packet transmitted from the wireless communication terminal is received, and a signal generator for generating a random data packet.
The invention according to claim 11 is an access point selection program for selecting an access point in a wireless communication network composed of a plurality of wireless communication access points and a plurality of wireless communication terminals, wherein the wireless communication terminal performs communication. When selecting a partner access point to perform, a transmission request function that requests transmission of random data packets to a plurality of access points, and transmission from a plurality of access points in response to a request of the transmission request function The number of errors is minimized by the receiving function for receiving random data packets, the error number counting function for calculating the CRC32 of the data packet received by the receiving function and counting the number of FCS errors, and the counting by the error number counting function. The source access point of the communication An access point selection program for causing a computer to realize an access point selection function to be selected and a packet transmission function in which a plurality of wireless communication access points receive a request from the transmission request function and transmit random data packets. To achieve.
The invention according to claim 12 is a storage medium storing an access point selection program for selecting an access point in a wireless communication network composed of a plurality of wireless communication access points and a plurality of wireless communication terminals. When a communication terminal selects an access point with which to communicate, a transmission request function for requesting a plurality of access points to transmit random data packets, and a plurality of access points in response to a request for the transmission request function A receiving function for receiving random data packets transmitted in order from the error number, an error number counting function for calculating the CRC32 of the data packet received by the receiving function and counting the number of FCS errors, and a counting by the error number counting function The source access point with the smallest number of errors A computer-reading for causing a computer to realize an access point selection function for selecting an access point and a packet transmission function for a plurality of wireless communication access points to transmit random data packets in response to a request from the transmission request function The object is achieved by a storage medium storing a possible access point selection program.

  According to the present invention, compared with the conventional method of selecting a communication partner access point from a plurality of access points, a very simple control can be achieved by adding a small circuit / program to a wireless communication signal processing circuit or program. It can be realized by a sequence.

Hereinafter, a preferred embodiment of the present invention will be described with reference to FIGS. Although this embodiment will be described using a wireless LAN as an application, it can also be applied to other wireless communication networks having the same network form.
FIG. 1 is a diagram illustrating an example of a wireless communication network according to the present embodiment. As shown in this figure, there are a plurality of access points (AP1, AP2, AP3) with which a certain wireless communication terminal can communicate.
FIG. 2 is a block diagram showing the configuration of the wireless communication terminal. When this wireless communication terminal detects the same wireless signal processing block 50 as before, the FCS (CRC32) calculation block 52 for determining the FCS error of the data packet transmitted from the access point, and the FCS error, An FCS error counter block 54 for counting the number of errors, a register group / memory 56 for holding an error count associated with each access point, an FCS error counter comparator 58, an access point selection request packet, and reception An ACK transmission block 60 that transmits a response packet and a received signal strength measurement block 62 are configured.

Note that the AP selection request packet includes a packet generation block in the conventional wireless processing block, and the other transmission processing is the same as the conventional wireless signal processing. Further, the ACK for the packet transmitted from the access point can be processed by the conventional radio signal processing block.
Also, the register group / memory 56 that holds the number of errors may be increased by the number of registers in consideration of the case where measurement is performed for each wireless channel. Furthermore, there is no need to mount a block supplemented by a conventional wireless communication signal processing block.
Note that the error counting method need not be limited to FCS (CRC32), and may be replaced with another method.

On the other hand, FIG. 3 is a block diagram showing the configuration of the access point. This access point includes a radio signal processing block 70 similar to the conventional one, a received packet decoder block 72 for determining that the received signal is an access point selection request signal and confirming its field value, and a radio communication terminal A decrement counter block 74 that receives a reception response packet from the packet and decrements its own transmission order, and a packet whose payload field is random data according to the field value of the access point transmission request packet in the case of its own transmission order And a random data generation block 76 for generating.
Further, both the wireless communication terminal and the access point can bypass all the above blocks when there is a single access point in the wireless communication network.
A block supplemented by a conventional radio signal processing block does not need to be mounted in a circuit / program again.

Next, a method for selecting a plurality of access points according to the present embodiment will be described.
First, in the first embodiment, random data packets are sequentially transmitted from the access point to the wireless communication terminal. The wireless communication terminal receives data packets sequentially from a plurality of access points, calculates the CRC 32, and counts the number of FCS errors in the FCS error count block 54. This is compared by the FCS error count comparator 58, and the transmission source access point with the smallest number of errors is selected as the communication partner. Then, the selection result is transmitted as an access point selection request packet and a reception response packet.
And select an access point.

In the second embodiment, the wireless communication terminal broadcasts an access point selection request packet to a plurality of access points all at once. FIG. 4 is a diagram showing an example of an access point selection request packet transmitted at this time. As shown in FIG. 4, the reserved bit of the field type / subfield type of the MAC header field defined in the wireless communication standard is used to indicate a data transmission request to the access point. It includes fields indicating the communication rate, payload length, number of packets, transmission power of data transmitted from a point, and the transmission order of access points among a plurality of access points.
On the other hand, when each access point receives an access point selection request packet from a wireless communication terminal, it checks all the above fields and waits until its data transmission order arrives.
When the wireless communication terminal finishes receiving data from one access point, it transmits a reception end response packet (ACK) by broadcast so that all access points can receive it. The point decrements the counter value indicating the transmission order. Thereafter, when the counter value becomes 0, random data is transmitted after the reception of ACK is completed.
By selecting an access point according to the above procedure, the procedure up to selection is very simple, and the circuit or program implementation scale is reduced. Further, the number of FCS errors of all channels that can be communicated at each access point may be counted. Furthermore, by setting the communication rate to the maximum for all access points, it is possible to substantially select the access point with the maximum throughput.

Next, an example of processing when the number of FCS errors transmitted from a plurality of access points matches will be described.
When the numbers of FCS errors transmitted from a plurality of access points match, the access point with the larger received signal strength measured by the received signal strength measurement block 62 is selected as the communication partner. In addition, when it is difficult to implement a circuit / program for measuring received signal strength, an access point may be selected at random.
If communication has not yet started and the wireless communication terminal has never selected which access point to communicate with, the wireless communication terminal recognizes the access point that can scan and communicate. To do. The wireless communication terminal broadcasts an access point selection request packet after performing authentication work with all access points and making data communication possible.
In addition, if the FCS error rate measured by the wireless communication terminal exceeds the threshold determined from the beginning, the data is being scanned, but there is an access point that has been scanned again and the authentication operation has not been completed. Perform authentication work. Then, by transmitting the access point selection request packet, the access point as the communication partner is selected again.
However, if there is a single access point that can be communicated as a result of scanning, the above access point selection procedure is not performed.

Next, the processing procedure of the present embodiment will be described with reference to the flowchart of FIG.
In a wireless communication network as shown in FIG. 1 composed of a plurality of access points and wireless communication terminals, when the wireless communication terminal starts wireless communication from now on, a scan is performed in the same manner as in a conventional wireless LAN (steps). 10) Recognize all accessible access points. Then, authentication is performed with all access points (step 11). When the authentication work with all access points is completed, the wireless communication terminal broadcasts an access point selection request packet as shown in FIG. 4 to all access points (step 12).
On the other hand, when the access point (AP) side receives the access point selection request packet (step 20), the field value of the packet is confirmed, and the communication rate, payload length, packet of random data to be transmitted to the wireless communication terminal is confirmed. Check the number, transmission order, transmission power, etc.
The access point to be transmitted first transmits a packet whose payload field is random under the conditions indicated in the access point selection request packet field, and the wireless communication terminal receives the specified number of packets and receives an FCS error. Count. When data reception from one access point is completed (step 13), the wireless communication terminal transmits a reception response packet (ACK) (step 14).

The access point that has received this response packet (step 21; N, step 23) decrements the counter value indicating the transmission order indicated in the access point selection request packet by 1 (step 24), and the count value is 0. Then, a specified number of data packets having a random payload field are transmitted to the wireless communication terminal (step 21; Y, step 22).
On the other hand, on the wireless communication terminal side, the above exchange is repeated by the number of access points (step 15; N). Here, a register that can be set to perform error count for each wireless channel may be mounted. If the communication rate is fixed at the maximum rate, communication with an access point having the highest throughput is possible.
When data from all access points is received (step 15; Y), the wireless communication terminal selects an access point with the smallest FCS error as a communication partner, and performs subsequent communication with the selected access point (step 16). . In addition, the FCS error count is always performed on the received packet even during the communication, and if it exceeds the originally determined PER (eg, 10%) (step 17; Y), the access point selection request packet is transmitted again. (Step 12) to select an access point for communication.

If the FCS error counts of data packets from a plurality of access points match, the access point with the higher signal strength measured by the received signal strength measurement block 62 is selected, and the signal strength is not determined. Thus, it may be selected at random.
Further, although the error count method is described as being obtained by FCS calculation, other methods may be adopted without particular designation.

It is the figure which showed the example of the radio | wireless communication network which concerns on a present Example. It is the block diagram which showed the structure of the radio | wireless communication terminal which concerns on a present Example. It is the block diagram which showed the structure of the access point which concerns on a present Example. It is the figure which showed the example of the access point selection request packet. It is the flowchart which showed the process sequence of the present Example.

Explanation of symbols

50 Radio signal processing block 52 FCS (CRC32) calculation block 54 FCS error counter block 56 Register group / memory 58 FCS error counter comparator 60 ACK transmission block 62 Received signal strength measurement block 70 Radio signal processing block 72 Receive packet decoder block 74 Clement counter block 76 Random data generation block

Claims (12)

A wireless communication network composed of a plurality of wireless communication access points and a plurality of wireless communication terminals,
Wireless communication terminal
A transmission request means for requesting a plurality of access points to transmit random data packets when selecting an access point of a communication partner;
Receiving means for receiving random data packets transmitted in order from a plurality of access points in response to a request from the transmission request means;
An error number counting means for calculating the CRC32 of the data packet received by the receiving means and counting the number of FCS errors;
An access point selection means for selecting a transmission source access point with the smallest number of errors as an access point for the communication as counted by the error number counting means, and a plurality of wireless communication access points are requested from the transmission request means. And a packet transmission means for transmitting random data packets.   When the transmission request means makes a random data packet transmission request to each access point, a transmission request packet indicating a packet having a unique protocol field using a reserved bit in the type / subtype field of the MAC header field. 2. The wireless communication network system according to claim 1, wherein a certain access point selection request packet is simultaneously transmitted to a plurality of access points.   In the access point selection request packet, the unique protocol field includes the communication rate, payload length, number of packets, transmission power field of the packet transmitted by each access point, and the transmission order of the access point among a plurality of access points. The wireless communication network system according to claim 2, further comprising a field indicating   The order in which the packet transmission means transmits data packets to the wireless communication terminal is indicated in the field indicating the transmission order of random data packets transmitted from the transmission request means, and is transmitted from each access point. In response to the data packet, the wireless communication terminal transmits a reception response packet, and the access point that has received the reception response packet decrements the transmission order, and transmits the data packet when the transmission order count value becomes zero. The wireless communication network system according to claim 1, 2, or 3.   2. The access point having the maximum received signal strength is selected as a communication partner when the number of FCS errors of packets transmitted from a plurality of access points counted by the error number counting means match. The wireless communication network system described.   When the access point selection means has not yet selected an access point as a communication partner, it recognizes a plurality of access points that are candidates for communication by scanning, and performs data authentication by performing authentication work with all access points. 2. The wireless communication network system according to claim 1, wherein the transmission requesting unit requests transmission of a random data packet after making it possible to perform transmission.   When the access point selection unit has selected an access point for the communication, the transmission request unit randomly sets a plurality of access points when the number of FCS errors exceeds a certain threshold by counting by the error number counting unit. 2. The wireless communication network system according to claim 1, wherein a request is made to transmit a data packet, and an access point as a communication partner is selected again.   8. The access point is not selected when the transmission request unit requests a random data packet to be transmitted, and the access point is not selected. 8. Wireless communication network system.   The wireless communication terminal includes a wireless communication signal processing block, an FCS (CRC32) calculation block, an FCS error count block, a register holding an error count corresponding to a plurality of access points, and a comparator for comparing the number of FCS errors. The wireless communication network system according to claim 1, further comprising: a transmission block that transmits an access point selection request packet and a reception response packet; and a block that measures received signal strength.   When the access point receives a wireless communication signal processing block, a reception packet decoder block for determining that the received packet is an access point selection request packet, and a reception response packet transmitted from the wireless communication terminal, the access point decrements a transmission order counter. 10. The wireless communication network system according to claim 1, further comprising a counter block for incrementing and a signal generator for generating a random data packet. An access point selection program for selecting an access point in a wireless communication network composed of a plurality of wireless communication access points and a plurality of wireless communication terminals,
Wireless communication terminal
A transmission request function for requesting a plurality of access points to transmit random data packets when selecting an access point of a communication partner;
In response to the request for the transmission request function, a reception function for receiving random data packets transmitted in order from a plurality of access points;
An error number counting function for calculating the CRC32 of the data packet received by the reception function and counting the number of FCS errors;
An access point selection function for selecting a transmission source access point with the smallest number of errors as an access point of the communication, by counting by the error count function,
Multiple wireless communication access points
An access point selection program for causing a computer to realize a packet transmission function for transmitting a random data packet in response to a request from the transmission request function. A storage medium storing an access point selection program for selecting an access point in a wireless communication network composed of a plurality of wireless communication access points and a plurality of wireless communication terminals,
Wireless communication terminal
A transmission request function for requesting a plurality of access points to transmit random data packets when selecting an access point of a communication partner;
In response to the request for the transmission request function, a reception function for receiving random data packets transmitted in order from a plurality of access points;
An error number counting function for calculating the CRC32 of the data packet received by the reception function and counting the number of FCS errors;
An access point selection function for selecting a transmission source access point with the smallest number of errors as an access point of the communication, by counting by the error count function,
Multiple wireless communication access points
A storage medium storing a computer-readable access point selection program for causing a computer to realize a packet transmission function for transmitting a random data packet in response to a request from the transmission request function.

Images