JP2006086782A - Radio communication equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately detect the quality of a communication environment involving each radio communication equipment in an ad-hoc mode communication system. <P>SOLUTION: A station 30a detects the respective received signal strengths of radio signals transmitted from the other stations 30b-30i. Received signal strength information corresponding to each station 30b-30i is graded to a plurality of quality levels, respectively. The quality of the communication environment involving the station 30a is evaluated based on the distribution of the number of stations responsible for each quality level. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a radio communication technique, and more particularly to a radio communication apparatus used in a radio communication system in which a plurality of radio communication apparatuses transmit and receive signals without going through a base station or an access point.

  In recent years, wireless LAN systems compliant with IEEE802.11 have become widespread as one of wireless communication systems. Here, in a wireless LAN system compliant with IEEE802.11, infrastructure mode communication and ad hoc mode communication are defined. In infrastructure mode communication, as shown in FIG. 18A, a plurality of stations (mobile terminals) communicate via an access point (or base station). On the other hand, in the ad hoc mode communication, as shown in FIG. 18B, a plurality of stations communicate without going through an access point.

  By the way, in the wireless communication system, the quality of the communication environment in which each communication device is placed is different. Furthermore, when the position (or installation location) of the communication device changes, the relative positional relationship between the communication devices also changes accordingly, and the quality of the communication environment in which each communication device is placed also changes. Therefore, in order to ensure the communication quality of the wireless communication system, it is necessary to individually monitor the quality of the communication environment in which each communication terminal is placed.

  In an infrastructure mode wireless LAN system compliant with IEEE802.11, communication between stations is always performed via an access point. Therefore, if the communication state between the access point and each station is examined, each station is placed. The quality of the communication environment can be detected. Therefore, in the infrastructure mode, the quality of the communication environment in which each station is placed is determined by, for example, the received signal strength of the beacon transmitted from the access point.

  On the other hand, in an ad hoc mode wireless LAN system, since there is no access point, it is necessary to detect the quality of the communication environment in which each station is located based on signals transmitted and received between the stations. However, so far, no suitable proposal has been made. Note that this problem is not limited to ad-hoc mode communication of a wireless LAN compliant with IEEE802.11, and is also a problem in a wireless communication system in which each wireless communication device transmits and receives signals without going through a base station or an access point. It has become.

As a related technique, Patent Document 1 describes a technique for evaluating the quality of a communication path between stations based on an SN ratio or a bit error rate in a wireless network. Patent Document 2 describes a technique for calculating a distance between stations based on received radio wave intensity in an ad hoc mode network. Furthermore, Patent Document 3 describes a technique for determining whether or not a wireless communication device is located in a communication permission area by comparing the strength of a received signal with a preset threshold value.
JP-T-2001-505035 (summary) Japanese Patent Laying-Open No. 2004-15147 (FIG. 1, paragraphs 0016 to 0020) JP 2003-169367 A (paragraphs 0016 to 0017)

  An object of the present invention is to appropriately detect the quality of a communication environment in which each wireless communication device is placed in a wireless communication system in which a plurality of wireless communication devices transmit and receive signals without going through a base station or an access point. is there.

  The radio communication system of the present invention is used in an ad hoc mode radio communication system. And collecting means for collecting quality information relating to the quality of communication with each of the plurality of wireless communication devices based on wireless signals respectively transmitted from the plurality of other wireless communication devices; Comparing means for comparing the corresponding quality information with a predetermined threshold value, respectively, and a ratio of the number of wireless communication devices whose quality information is less than the threshold value to the total number of the other plurality of wireless communication devices And evaluation means for evaluating the quality of the communication environment in which the wireless communication device is placed in the wireless communication system.

  In the present invention, the quality of the communication environment in which the local station is placed is evaluated according to the proportion of wireless communication devices having deteriorated communication quality. Therefore, if the threshold value is appropriately set, it is possible to determine whether the location of the own station is inappropriate or the configuration of a small number of other wireless communication devices, and the communication environment can be appropriately evaluated.

  A wireless communication device according to another aspect of the present invention is used in a wireless communication system in an ad hoc mode, and uses the collection means and corresponding quality information to determine a quality level for the other wireless communication devices. Ranking means for performing ranking, and evaluation means for evaluating the quality of the communication environment in which the wireless communication device is placed in the wireless communication system, based on the distribution of the number of wireless communication devices belonging to each quality level. Have.

  In the present invention, a plurality of quality levels are defined, and the quality of the communication environment in which the station is located is evaluated based on the distribution of the number of wireless communication devices belonging to each quality level. Therefore, it is possible to grasp the rough arrangement of all the wireless communication devices in the system, and it is possible to more accurately evaluate the quality of the communication environment.

  A radio communication apparatus according to yet another aspect of the present invention is used in an ad hoc mode radio communication system, and the radio communication apparatus in the radio communication system is based on the collecting means and the worst value in the collected quality information. Evaluation means for evaluating the quality of the communication environment in which In the present invention, it can be easily determined whether or not communication with all wireless communication apparatuses can be guaranteed.

  Note that the collection unit of the above-described wireless communication device may collect information indicating the received signal strength of the beacon signal that is broadcast from each of a plurality of other wireless communication devices as the quality information. Since the beacon signal is transmitted at a predetermined power and a predetermined data rate, it is suitable for determining whether or not the signal from the transmission source wireless communication apparatus can be received.

  According to the present invention, since the quality of the communication environment in which each wireless communication device is placed in the ad hoc mode communication system can be appropriately evaluated, it is possible to provide useful information when each device is arranged. In addition, it is possible to accurately detect deterioration of the communication environment when the wireless communication device moves while using ad hoc mode communication.

  Embodiments of the present invention will be described with reference to the drawings. In the following, an ad hoc mode communication system of a wireless LAN compliant with IEEE802.11 is taken as one form of a wireless communication system in which a plurality of wireless communication devices (hereinafter referred to as stations) transmit and receive signals without going through a base station or an access point. .

  In the ad hoc mode communication system, as shown in FIG. 18B, communication is performed between stations without using an access point. At this time, each station basically needs to be able to communicate with all other stations in the system. Accordingly, each station monitors the quality of the communication environment in which it is located in the system. In this specification, “ad hoc mode communication” is not limited to a wireless LAN compliant with IEEE802.11, but a method in which a plurality of wireless communication devices transmit and receive signals without going through a base station or an access point. Means. In addition, inter-mobile communication in which wireless communication apparatuses mounted on automobiles or the like transfer data using a relay method is also a form of ad hoc mode communication.

  FIG. 1A and FIG. 1B are diagrams illustrating a configuration example of a communication system according to an embodiment. Here, the wireless communication system 100 is constructed including two basic service sets (IBSS). Stations 10a to 10d belong to one basic service set (IBSS1), and stations 10e to 10h belong to the other basic service set (IBSS2). As described above, the communication areas of the basic service set may overlap each other or may be separated from each other.

  The basic service set is a logically separated network and is constructed by giving a basic service set identifier (BSSID) to each station. Here, the basic service set to which each station belongs is determined according to a procedure defined in IEEE 802.11, for example. Then, the MAC processing unit of each station discards a frame transmitted from a station belonging to a basic service set different from the basic service set to which the own station belongs. Thereby, logical separation of the basic service set is realized.

  FIG. 2A is a diagram illustrating a format of a beacon frame transmitted / received between stations. A beacon is a signal for informing various wireless stations necessary for communication to neighboring wireless stations. Here, in the ad hoc mode communication system, the beacon transmission opportunity is allocated to each station by random backoff, so that each station transmits a beacon substantially evenly. In addition, the beacon is transmitted with a predetermined power that allows the beacon to be received in the entire communication area of each basic service set.

  A beacon frame includes a MAC header, a frame body, and a frame check sequence (FCS). Here, the MAC header includes a destination address, a source address, and a basic service set identifier (BSSID). “Broadcast” is set as the destination address. The source address is the MAC address of the station that sends out the beacon frame. The basic service set identifier (BSSID) identifies the basic service set to which the station transmitting the beacon frame belongs. Therefore, the station that received the beacon can detect the MAC address of the station that transmitted the beacon and the basic service set to which the station belongs. In the frame body, information to be notified to surrounding stations is stored. The frame check sequence (FCS) is information for detecting a bit error at the receiving station, and, for example, a CRC (Cyclic Redundancy Check) calculation value is written therein.

  FIG. 2B is a diagram illustrating a format of a data frame transmitted / received between stations. The data frame can specify the MAC address of a specific station as a destination, or can be broadcast to all stations.

  By the way, in order to correctly operate the above-described ad hoc mode communication, it is necessary to determine the arrangement of stations so that communication is established between all the stations belonging to the basic service set for each basic service set (or Need to determine the scope of the basic service set). Here, it is generally said that the radio field intensity of a radio signal is attenuated in proportion to the 3rd to 3.5th power of the propagation distance. Therefore, the stations belonging to each basic service set of ad hoc mode communication should be arranged within a predetermined radius, assuming that the influence of obstacles and multipath fading is not considered. At this time, the reach distance of the radio frame from the station corresponds to the diameter of the circle of the basic service set.

  FIG. 3 is a diagram for explaining the quality of the communication environment. Here, it is assumed that nine stations 20a to 20i belong to the basic service set. The quality of the communication environment where the station 20a is placed is monitored.

  In the state shown in FIG. 3A, the station 20a can successfully receive radio signals from all the other stations 20b to 20i. That is, in this case, it is determined that at least the station 20a is arranged at an appropriate position.

  In the state shown in FIG. 3B, the station 20a moves away from the stations 20b to 20i as compared to the state shown in FIG. As a result, the station 20a cannot receive the radio signals from the stations 20c and 20g satisfactorily. At this time, the stations 20c and 20g cannot receive the radio signal from the station 20a, respectively. That is, in the ad hoc mode communication, the stations are equal to each other. Therefore, in the state shown in FIG. 3B, it can be determined that the station 20a is improperly arranged, and the stations 20c and 20g are not arranged. It can also be judged appropriate.

For this reason, each station of the embodiment has a function of monitoring the quality of the communication environment in which the station is placed.
In the example shown in FIG. 3, it has been described that the cause of communication quality deterioration is due to the distance between stations. However, the present invention is not limited to this, and changes in multipath fading and external noise are not limited. Similarly, it is possible to monitor communication quality deterioration due to the influence of the above.

FIG. 4 is a functional block diagram of the station according to the embodiment. Here, functions not directly related to the present invention are omitted.
The station 30 includes a reception unit 31, a transmission unit 32, a MAC processing unit 33, and an upper level processing unit 34. The receiving unit 31 receives a radio signal transmitted from another station via the antenna 35. The transmission unit 32 transmits the frame created by the MAC processing unit 33 via the antenna 35. The MAC processing unit 33 includes a processor and a memory, and executes general MAC processing. The MAC processing unit 33 includes a collection unit 41, a station information table 42, a comparison unit 43, and an evaluation unit 44, and evaluates the quality of the communication environment in which the own station (the station) is placed in the wireless communication system. The upper level processing unit 34 outputs the evaluation result obtained by the MAC processing unit 33. Although the output of the evaluation result is not particularly limited, for example, display of the evaluation result, generation of an alarm corresponding to deterioration of the communication environment, and the like.

  The collection unit 41 collects quality information related to the quality of communication with each station based on radio signals transmitted from a plurality of other stations. As quality information, in this embodiment, a received signal strength indicator (RSSI) is measured. The quality information is not particularly limited as long as it represents the communication quality between stations. For example, a correlation value when a signal spread by a spreading code is despread on the transmission side is detected. May be. Information collected by the collection unit 41 is stored in a station information table 42 described later.

  The comparison unit 43 compares the quality information corresponding to each station with a predetermined threshold value. Instead of the comparison unit 43, a ranking unit 45 may be provided that ranks the quality levels for the other stations using the corresponding quality information.

  Based on the comparison result by the comparison unit 43 or the ranking result by the ranking unit 45, the evaluation unit 44 places the own station in the basic service set to which the own station (that is, the wireless communication device) belongs. Evaluate the quality of the communication environment.

  The collection unit 41, the comparison unit 43, the evaluation unit 44, and the ranking unit 45 are realized by a processor that executes a program described in advance. However, some functions of the collection unit 41, the comparison unit 43, the evaluation unit 44, and the ranking unit 45 may be realized by hardware.

  FIG. 5 is an example of the station information table 42. When the station 30 receives a radio signal from another station, the station 30 registers necessary information in the station information table 42.

  The “source MAC address” is the MAC address of the source station of the received radio signal. Here, the radio signal to be targeted is, for example, a beacon frame periodically broadcast from each station. Since a signal is transmitted in a beacon frame at a predetermined power and a predetermined data rate, it is suitable for determining whether or not a signal from the station can be received. However, a data frame transmitted from another station to the station, a data frame transmitted / received between other stations, or a broadcast data frame may be targeted. The source MAC address is extracted from the MAC header of the received frame as shown in FIG. 2 (a) or 2 (b).

  As the “reception quality information”, in this embodiment, the received signal strength RSSI measured for the received radio signal is written. The “basic service set identifier (BSSID)” is an identifier for identifying the basic service set to which the transmission source station of the received radio signal belongs. The basic service set identifier is extracted from the MAC header of the received frame in the same manner as the transmission source MAC address.

  In the example shown in FIG. 5, the reception quality information is registered for all the received frames, but only the frames in the basic service set to which the own station belongs may be targeted. In this case, the collection unit 41 sets the reception quality information to the station information only when the basic service set identifier set in the MAC header of the received frame matches the basic service set identifier of the basic service set to which the own station belongs. Register in the table 42. With this configuration, the required memory is reduced.

The maintenance of the station information table 42 is performed by the following method, for example.
(1) The time when the frame was last received is recorded for each station, and the record of the station is deleted when a certain time has elapsed from that time (aging). If this procedure is introduced, it is possible to prevent information relating to the station from remaining in the table when the station moves out of the basic service set area or when the power is turned off. Further, error factors in the comparison unit 43 or the evaluation unit 44 can be reduced.

  (2) If there are more stations than the number of entries in the table, the reception quality information relating to the newly received frame is registered and the oldest information is deleted from the table (priority for new arrival). If this method is introduced, the table size can be limited to a reasonable size. In addition, since the station that wants to know the communication state is considered to be communicating more actively, it can make an appropriate decision using the latest quality information.

  (3) When each station turns off the power, it notifies other stations of that fact, and deletes the corresponding record from the table according to the notification. In this case, unnecessary quality information can be deleted without waiting for the predetermined time of (1), so that a more accurate determination can be made.

Next, specific examples of communication environment quality evaluation will be described.
First Method In the first method, the station information table 42 is searched, and the value of the worst reception quality information is estimated as the quality of the communication environment where the own station (that is, the station) is placed. This method is realized by the following procedure.

  Step S1: The station information table 42 is searched, and a record in which the same basic service set identifier as the basic service set identifier for identifying the basic service set to which the own station belongs is extracted. Note that the process in this step is omitted when there is only one basic service set in the wireless communication system or when all stations in the wireless communication system are targeted.

  Step S2: The worst value is selected from the reception quality information of each extracted record. At this time, when the received signal strength is used as the received quality information, the minimum value is selected. In the example shown in FIG. 5, the received signal strength of the signal transmitted from the station to which “MAC address = 00-07-C3-BB-BB-BB” is assigned is the minimum.

  Step S3: The quality of the communication environment is evaluated based on the worst value selected in Step S2. In ad hoc mode communication, basically, it is necessary to communicate with all other stations, so it is also necessary to communicate with a station having the minimum received signal strength. Therefore, this minimum value can be considered as the quality of the communication environment in which the station is placed. Specifically, for example, if the minimum value of the received signal strength selected in step S2 is larger than a predetermined quality threshold, it is evaluated that communication with all stations is possible and the communication environment is good. . On the other hand, if the minimum value of the received signal strength selected in step S2 is smaller than a predetermined quality threshold value, it is difficult to communicate with the station having the minimum received signal strength, and the communication environment is not good. Is done.

Second Method In the second method, the quality of the communication environment in which the own station (that is, the station) is placed is evaluated according to the ratio of the number of stations in which the reception quality information is deteriorated with respect to the total number of stations. . This method is realized by the following procedure.

Step S1: Same as step S1 of the first method.
Step S2: The number of extracted stations is detected.
Step S3: Each extracted reception quality information is compared with a predetermined quality threshold value. If the reception quality information is the received signal strength, this quality threshold is, for example, the received signal strength that the error rate when the received signal is decoded / demodulated is expected to be a predetermined value or less, and is determined by experiment or simulation. Is done.

Step S4: The number of stations whose reception quality information is lower than the quality threshold is detected.
Step S5: The quality of the communication environment is evaluated according to whether or not the ratio of the number of stations detected in step S4 to the number of stations detected in step S2 exceeds a predetermined ratio threshold value. Here, for example, the total number of stations operating in the basic service set is “9 (including own station)”, the quality threshold value in step S3 is “80”, and the ratio threshold value in step S5 is “50 percent”. Shall. Then, for example, if the number of stations whose reception quality information is less than 80 is 3, the ratio of stations whose reception quality has deteriorated is 3/8 (about 38%), which is 50% or less, so the communication environment is good. Evaluated as being. On the other hand, if the number of stations whose reception quality information is less than 80 is 5, the ratio of stations whose reception quality has deteriorated is 5/8 (about 63%), which is 50% or more, so the communication environment is bad. Be evaluated.

  FIG. 6 is a diagram illustrating the first method and the second method in comparison. Here, nine stations including the stations 30a and 30b are provided in the basic service set, and the quality of the communication environment in which the station 30a is placed is evaluated.

  In the state shown in FIG. 6A, only the station 30a is disposed at a position away from the other eight stations. In this case, it is necessary to pay attention to the arrangement of the stations 30a. On the other hand, in the state shown in FIG. 6B, only the station 30b is disposed at a position away from the other eight stations. In this case, there is no problem in the arrangement of the station 30a, and it is necessary to pay attention to the arrangement of the station 30b.

  In the first method, the communication quality is evaluated based on the worst value of the reception quality information. For this reason, in any of the cases shown in FIGS. 6A and 6B, the quality information related to the received signal from the station 30b is the worst value, and thus the difference between these two states cannot be determined. On the other hand, in the second method, the communication quality is evaluated by the ratio of the number of stations in which the reception quality information is deteriorated with respect to the total number of stations. For example, in the example shown in FIG. 6A, the ratio is “3/8”, whereas in the example shown in FIG. 6B, it is “1/8”. Therefore, according to the second method, the difference between the two states can be detected.

Third Method In the third method, the quality information corresponding to each station is ranked into a plurality of quality levels, and based on the distribution of the number of stations belonging to each quality level, the own station (that is, the station) Evaluate the quality of the communication environment. This method is realized by the following procedure.

Step S1: Same as step S1 of the first method.
Step S2: Each extracted reception quality information is compared with a plurality of predetermined quality thresholds. Thereby, each station is ranked for a plurality of quality levels defined by their plurality of quality thresholds.

Step S3: The number of stations belonging to each quality level is detected.
Step S4: Communication quality is evaluated based on the distribution of the number of stations belonging to each quality level.

  A specific example of the third method will be described with reference to FIGS. 7 (a) to 7 (d). In this embodiment, as shown in FIGS. 7A and 7B, four quality threshold values are provided. Then, five quality levels are defined by these quality thresholds. In the state shown in FIG. 7B, the quality information of the received signals from the stations 30b and 30c is “80 or higher (A rank)”, and the quality information of the received signals from the stations 30d and 30e is “65 to 80 ( B rank) ”, the quality information of the received signal from the station 30f is“ 50 to 65 (C rank) ”, and the quality information of the received signal from the stations 30g, 30h, 30i is“ 30 to 50 (D rank) ”. ) ”. In this case, the ranking shown in FIG. 7C is obtained. Further, by counting the number of stations belonging to each rank, the result shown in FIG. 7D is obtained.

Next, simulations and evaluations relating to the third method will be described. The following simulation was performed assuming that the number of stations is 32 (including the own station) and that the reception quality information is the received signal strength RSSI. Here, the received signal strength was calculated as inversely proportional to the cube of the distance between stations (RSSI = log ₁₀ (1 / L ³ )).

  8 to 17 are diagrams illustrating simulation results related to the third method. In the layout diagrams drawn in the left area of each figure, each dot represents a station, and an asterisk represents its own station (that is, a station for quality evaluation). The distribution chart drawn in the right area of each figure represents the state of other stations as seen from the own station, the horizontal axis represents reception quality information (in this case, received signal strength RSSI), and the vertical axis represents The ratio of stations belonging to each quality when the total number of stations is normalized to “1” is shown. In the distribution diagram, threshold values for the reception quality information and threshold values for the ratio are drawn as a guide for evaluating the quality.

  As shown in FIG. 8 or FIG. 9, if the quality information relating to all or most of the stations is equal to or greater than the threshold, the quality of the communication environment of the own station is evaluated as “good”. On the other hand, it is evaluated that the quality deteriorates as the number of stations whose corresponding quality information is equal to or less than the threshold value increases. In particular, as shown in FIG. 15 or FIG. 16, when the peak position of the distribution is equal to or lower than the threshold and the peak is sufficiently high, it is evaluated that the degree of risk is high. Also, as shown in FIGS. 10 to 12, as the own station moves away from other stations, the distribution shifts accordingly. Therefore, quality deterioration can be detected in advance by monitoring the tendency of this distribution to shift on the time axis.

The evaluation result may be displayed on the display device of each station, may be output by voice guidance, or may be notified to other devices.
Other Embodiments The wireless communication apparatus of the present invention is not limited to the configurations and operations of the above-described embodiments, and can be applied to the following modes.

  (1) Evaluate the communication environment based on the number of operating stations. For example, when the number of operating stations is gradually decreasing, it can be determined that the own station is moving away from other stations.

  (2) Each station detects the mutual positional relationship by exchanging the station information table 42 with each other. At this time, if the position of an arbitrary station can be specified by GPS or the like, the absolute position of each station can be determined.

(3) By detecting all received frames, the degree of congestion of the wireless channels in the surrounding area is detected.
(4) When reception quality information from a specific station (for example, a station with high importance such as a station connected to a backbone line) deteriorates, an alarm is immediately output.

  (5) Collect reception quality information not only for the basic service set to which the station belongs, but also for other basic service sets. When the communication environment quality deteriorates, the basic service set of the transfer destination is selected using the collected information.

  (6) A beacon frame is generally slower than a data frame and has a shorter frame length. That is, a beacon frame can be received even in a situation where the communication environment deteriorates and data frame reception errors increase. Therefore, the station information table 42 is more properly maintained by using the beacon frame as the acquisition source of the reception quality information.

  (7) A retransmission sequence number is set as management information in each unicast frame transmitted / received between stations. When a unicast frame addressed to the own station is received, the retransmission sequence number of the frame is collected as reception quality information. For example, if the number of retransmissions is small, it is determined that the communication environment is good.

  (8) Change the evaluation frequency according to the state of communication environment quality. For example, if the communication environment is good, the frequency of evaluation is decreased, and the frequency of evaluation is increased as it deteriorates.

It is a figure which shows the structural example of the communication system of embodiment. (A) And (b) is a figure which shows the format of a beacon frame and a data frame, respectively. It is a figure explaining the quality of a communication environment. It is a functional block diagram of a station of an embodiment. It is an Example of a station information table. It is a figure explaining the 1st and 2nd methods in contrast. It is a figure explaining the specific example of a 3rd method. It is the simulation result (the 1) concerning a 3rd method. It is a simulation result (the 2) concerning a 3rd method. It is a simulation result (the 3) concerning a 3rd method. It is a simulation result (the 4) concerning a 3rd method. It is a simulation result (the 5) concerning a 3rd method. It is a simulation result (the 6) concerning a 3rd method. It is a simulation result (the 7) concerning a 3rd method. It is a simulation result (the 8) concerning a 3rd method. It is a simulation result (the 9) concerning a 3rd method. It is a simulation result (the 10) concerning a 3rd method. (A) And (b) is a figure which shows typically infrastructure mode communication and ad hoc mode communication, respectively.

Explanation of symbols

1 wireless communication system 10a to 10h station 20a to 20i station 30 station 30a to 30i station 31 receiving unit 32 transmitting unit 33 MAC processing unit 34 upper level processing unit 35 antenna 41 collection unit 42 station information table 43 comparison unit 44 evaluation unit 45 rank Attachment

Claims (4)

A wireless communication device used in an ad hoc mode wireless communication system,
Collection means for collecting quality information related to the quality of communication with each of the plurality of wireless communication devices based on wireless signals respectively transmitted from the other plurality of wireless communication devices;
Comparison means for comparing the quality information corresponding to each wireless communication device and a predetermined threshold value,
Based on the ratio of the number of wireless communication devices whose quality information is below the threshold to the total number of the other plurality of wireless communication devices, the quality of the communication environment in which the wireless communication device is placed in the wireless communication system is determined. Evaluation means to evaluate,
A wireless communication device. A wireless communication device used in an ad hoc mode wireless communication system,
Collection means for collecting quality information related to the quality of communication with each of the plurality of wireless communication devices based on wireless signals respectively transmitted from the other plurality of wireless communication devices;
Ranking means for ranking the quality level for the other wireless communication devices using the corresponding quality information;
Evaluation means for evaluating the quality of the communication environment in which the wireless communication device is placed in the wireless communication system, based on the distribution of the number of wireless communication devices belonging to each quality level;
A wireless communication device. A wireless communication device used in an ad hoc mode wireless communication system,
Collection means for collecting quality information related to the quality of communication with each of the plurality of wireless communication devices based on wireless signals respectively transmitted from the other plurality of wireless communication devices;
Evaluation means for evaluating the quality of the communication environment in which the wireless communication device is placed in the wireless communication system, based on the worst value in the collected quality information,
A wireless communication device. The wireless communication device according to any one of claims 1 to 3,
The collection means collects information indicating the received signal strength of a beacon signal broadcast from each of a plurality of other wireless communication devices as the quality information.

Images