JP7568864B2 - Communication device and communication system - Google Patents

Description

The present invention relates to a communication device used in a wireless network, and in particular to a communication device and communication system that realizes proper frame aggregation in a wireless network state and can avoid unauthorized occupation of a wireless line.

[Prior Art]
In mobile networks, mobile communication stations autonomously detect terminals between each other, autonomously optimize routes, and build ad-hoc wireless networks, thereby realizing communications that reduce latency while minimizing the load on the lines.

On the other hand, because it facilitates wireless network connections, it makes the environment vulnerable to network-related cyber attacks.
In wireless networks, a single frequency resource is often shared among multiple mobile communication stations, specifically, Time Division Multiple Access (TDMA) which is a multiple access access and Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) which is a contention avoidance method by carrier sense are used as specific sharing methods.

However, these methods often treat malicious communication as normal if there are no errors in the control information used in the communication, even when malicious communication occurs, and as a result, it is not easy to detect and block malicious communication.

[Conventional communication device: FIG. 8]
A communication device used in a conventional wireless network will be described with reference to Fig. 8. Fig. 8 is a schematic diagram of the configuration of a conventional communication device. Note that the flow of IP (Internet Protocol) packets is indicated by solid arrows, and the flow of control and information acquisition is indicated by dashed arrows.
As shown in FIG. 8, the conventional communication device 10 is made up of a network unit 110, a radio access control unit 120, a radio signal processing unit 130, and a high frequency unit 140.
In addition, a communication terminal 2, a control terminal 30, and an antenna 5 are connected to the communication device 10.

The network unit 110 mainly serves as an interface with a user terminal (communication terminal 2) such as a personal computer, and exchanges network information input from the user terminal, so-called IP packets, with the wireless access control unit 120.

The radio access control unit 120 judges, based on the IP packet received from the network unit 110, whether the frequency resource, that is, the radio line, is not in use, or whether it is time for transmission by the own station.
If the result of the no-determination is that the packet can be transmitted, the radio access control unit 120 generates the packet into a unit called a frame by adding control information to the IP packet, concatenates multiple frames, encrypts the information, and transfers it to the radio signal processing unit 130.

The radio signal processing unit 130 performs coding and interleaving to correct communication errors, then performs modulation processing to convert the signal into a carrier wave, adds synchronization signals, control signals, etc., and transfers the signal to the high frequency unit 140.
The high frequency unit 140 converts the received carrier wave into a high frequency wave, amplifies it to a specified power, and transmits it from the antenna 5 .

In the opposing receiving communication device, the high frequency section 140 receives a high frequency signal from the antenna 5 , converts it into a carrier wave, and outputs it to the radio signal processing section 130 .
The radio signal processor 130 demodulates the carrier wave, detects the synchronization signal and the control signal, and restores the digital information. After the restoration, it corrects any erroneous information and transmits it to the radio access controller 120.

The radio access control unit 120 decrypts encrypted digital information as necessary, judges whether the received digital information is a frame, judges whether the information is concatenated if it is a frame, and disassembles the frame if it is concatenated.
Thereafter, the radio access control unit 120 performs response processing, adjusts the transmission time, and so on, in accordance with the control information stored in the disassembled frames.

Furthermore, if an IP packet is stored in the frame, the radio access control unit 120 outputs it to the network unit 110 .
The network unit 110 judges from the received IP packet whether or not the packet is addressed to a user terminal to be connected, and transfers the packet to the user terminal.
In addition, the control terminal 30 displays and monitors the settings and communication status of the communication device 10.

In conventional wireless systems, data transfer using frame aggregation is performed by determining the amount of aggregation (the number of frames to be linked) based on conditions such as the congestion rate of the local station and the time specified by management stations such as base stations and access points.

[Related Technology]
As a related prior art, there is Japanese Patent No. 5848956 entitled "Communication Device" (Patent Document 1).
Patent Document 1 discloses a communication device that determines the data link size based only on the number of subcarriers used by the local station and the communication method.

Patent No. 5848956

However, in the above-mentioned conventional wireless system, when the wireless network is a temporary network, a so-called ad hoc network, as shown in Figure 9, base stations and access points cannot be prepared, and the aggregation amount is determined only by the congestion rate of the local station, which may result in the line being monopolized, and there is a problem that malicious communications cannot be detected and blocked.

Furthermore, Patent Document 1 does not describe a configuration for achieving appropriate frame aggregation in a wireless network state and for detecting and blocking malicious communications.

The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a communication device and a communication system that can realize appropriate frame aggregation in wireless network conditions, avoid unnecessary line occupation, and detect and block malicious communications.

The present invention, which aims to solve the problems of the above-mentioned conventional examples, is a communication device used in a wireless network in which a plurality of wireless stations have autonomously distributed access, which obtains an identifier of the wireless station from a received frame, obtains communication quality information at the timing of receiving the received frame, and further obtains information on the number of frames transmitted and received and the communication method for each wireless station, and determines the aggregation amount and aggregation method for the corresponding wireless station based on the quality information, the number of frames transmitted and received, and the communication method for each wireless station, and changes the aggregation method for linking communication frames.

In the above-mentioned communication device, the present invention determines the number of effective subcarriers of the signal to be transmitted and received, and changes the amount of aggregation by changing the number of frames to be linked in accordance with the number of effective subcarriers.

In the above-mentioned communication device, the present invention determines communication quality from the equalization error of the transmitted and received signals, selects an optimal modulation method according to the communication quality, and changes the aggregation amount by varying the number of frames to be concatenated according to the selected modulation method.

In the above-mentioned communication device, the present invention judges communication quality from the signal-to-noise ratio of a signal received from a wireless station, and changes the aggregation method for linking frames according to the communication quality.

In the above-mentioned communication device, the present invention determines priority information of wireless stations present within the communication range and changes the aggregation method according to the priority information.

The present invention is a communication system equipped with the above-mentioned communication device.

According to the present invention, a communication device used in a wireless network in which a plurality of wireless stations have autonomously distributed access acquires an identifier of the wireless station from a received frame, acquires communication quality information at the timing of receiving the received frame, and further acquires information on the number of frames transmitted and received and the communication method for each wireless station, and determines the aggregation amount and aggregation method for the corresponding wireless station based on the quality information, the number of frames transmitted and received, and the communication method for each wireless station, and changes the aggregation method for linking communication frames.Therefore, it has the effect of realizing appropriate frame aggregation in the state of the wireless network, avoiding unnecessary line occupation, and detecting and blocking malicious communications.

FIG. 2 is a schematic diagram of the configuration of the communication device. 2 is a schematic diagram showing the configuration of a transmission/reception frame and upper layer protocol data. FIG. FIG. 11 is a diagram illustrating an example of communication quality information. FIG. 11 is a diagram illustrating an example of communication method information. FIG. 11 is a flow diagram showing an aggregation amount determination process (1). FIG. 13 is a flow diagram showing the process (2) of determining the aggregation amount. FIG. 11 is a flow diagram showing a process of determining an aggregation method. FIG. 1 is a schematic diagram illustrating the configuration of a conventional communication device. FIG. 1 is a diagram illustrating an example of an ad hoc network.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings.
[Outline of the embodiment]
A communication device according to an embodiment of the present invention (this communication device) is a communication device used in a wireless network to which multiple wireless stations have autonomously distributed access, and changes the aggregation method for linking communication frames based on communication quality information acquired for each wireless station and information on the communication method of the wireless network.Therefore, it is possible to realize appropriate frame aggregation in the state of the wireless network, avoid unnecessary line occupation, and detect and block malicious communications.
Incidentally, a communication system in which this communication device is used in a wireless network is referred to as "this communication system."

[Overview of processing in this communication system]
An overview of the processing in this communication system will now be described.
A communication device in this communication system obtains an identifier of a communication station (wireless station) from a received frame, obtains communication quality information (communication quality information) at the time of receiving the received frame, and further obtains information on the number of frames transmitted and received and the communication method for each communication station, and determines the aggregation amount and aggregation method for the corresponding communication station based on the quality information, number of frames transmitted and received, and communication method for each communication station.

[This communication device: Figure 1]
This communication device will be described with reference to Fig. 1. Fig. 1 is a schematic diagram of the configuration of this communication device. Note that the flow of IP packets is indicated by solid arrows, and the flow of control and information acquisition is indicated by dashed arrows.
As shown in FIG. 1, the communication device 1 includes a network unit 11, a radio access control unit 12, a radio signal processing unit 13, and a radio frequency unit 14.
In addition, a communication terminal 2, a control terminal 3, and an antenna 5 are connected to the communication device 1.

[Network section 11]
The network unit 11 mainly serves as an interface with the communication terminals 2, such as IP telephone terminals and PCs, and the control terminal 3, and exchanges IP packets with the wireless access control unit 12 and sets the communication method.

In addition, the network unit 11 determines whether the IP packet input from the radio access control unit 12 is a packet intended for the connecting user terminal (communication terminal 2) from the received IP packet, and forwards the packet to the user terminal.

Furthermore, as will be described later, the network unit 11 of this communication device determines the aggregation amount and aggregation method of frame aggregation according to the communication method and the quality of the communication station, and notifies the radio access control unit 12 of them.
The specific internal configuration of the network unit 11 will be described later.

[Radio access control unit 12]
The wireless access control unit 12 monitors whether the wireless line is in use, and if it is available (line is not in use), outputs the IP packet input from the network unit 11 to the wireless signal processing unit 13. It also determines whether data has been reliably delivered to the other party in the wireless communication, and performs retransmission control as necessary.

In addition, the wireless access control unit 12 determines whether the frequency resources, i.e., the wireless line, are not in use or whether it is time for the local station to transmit, based on the IP packet input from the network unit 11. If the result is no determination and it is determined that transmission is possible, a frame is generated in which control information is added to the IP packet.

Furthermore, the radio access control unit 12 aggregates the generated frames by linking them together in accordance with the aggregation amount and aggregation method notified by the network unit 11, encrypts the information, etc., and outputs it to the radio signal processing unit 13.

The radio access control unit 12 decrypts encrypted digital information input from the radio signal processing unit 13 as necessary, determines whether the received digital information is a frame, and if it is a frame, determines whether it is linked, and if it is linked, disassembles the frame.

The radio access control unit 12 then performs response processing, adjusts the transmission time, and so on, in accordance with the control information stored in the decomposed frames.
Furthermore, if an IP packet is stored in the frame, the radio access control unit 12 outputs it to the network unit 11 .

The radio access control unit 12 includes a transmission/reception counter 121 and a signal quality acquisition unit 122 .
The transmission/reception counter 121 counts the number of frames transmitted and received for each communication station.
The signal quality acquisition unit 122 acquires communication quality information, which will be described later.

[Radio signal processing unit 13]
The radio signal processing unit 13 performs coding and interleaving to correct communication errors, then performs modulation processing to convert the signal into a carrier wave, adds synchronization signals, control signals, etc., and transfers the signal to the high frequency unit 14.
The radio signal processor 13 demodulates the signal, detects the synchronization signal and the control signal from the carrier wave, and restores the digital information. After the restoration, the radio signal processor 13 corrects any erroneous information and outputs the corrected information to the radio access controller 12.

[High frequency section 14]
The high frequency unit 14 converts the received carrier wave into a high frequency wave, amplifies it to a specified power, and transmits it from the antenna 5 .
Moreover, the high frequency unit 14 receives a high frequency signal from the antenna 5 , converts it into a carrier wave, and outputs it to the radio signal processing unit 13 .

[Control Terminal 3]
The control terminal 3 displays and monitors the settings and communication status of the communication device 10.
Specifically, the control terminal 3 has a display function for displaying setting information and communication status, and further has a priority information setting function for setting priority information.
The priority information that is set here is used when changing the frame aggregation method.

[Details of network unit 11]
The network unit 11 further includes a QoS function unit 111 , a frame transmitting/receiving unit 112 , a communication method function unit 113 , and a communication station quality management unit 114 .

[QoS function unit 111]
The QoS function unit 111 performs processing for guaranteeing communication quality, and includes an input scheduler, a packet queue, and an output scheduler, and also includes an aggregation management unit 111a as a feature of this device.
The QoS function section 111 also receives IP packets from the communication terminal 2 , outputs the packets to the frame transmitting/receiving section 112 , and outputs the IP packets from the frame transmitting/receiving section 112 to the communication terminal 2 .

[Aggregation management unit 111a]
The aggregation management unit 111a manages aggregation in this communication device 1, inputs communication quality information and the number of frames sent and received for each communication station from the communication station quality management unit 114, obtains communication method information from the communication method function unit 113, obtains priority information from the control terminal 3, determines the aggregation amount and aggregation method for the communication station, and outputs it to the radio access control unit 12 via the frame transmission/reception unit 112.
The radio access control unit 12 performs frame aggregation based on the aggregation amount and aggregation method.
The processing performed by the aggregation management unit 111a will be described in detail later.

[Frame transmitting/receiving unit 112]
The frame transmitting/receiving section 112 adds control information required for framing to the IP packet from the QoS function section 111 and outputs the packet to the radio access control section 12. The radio access control section 12 generates a frame in accordance with the input from the frame transmitting/receiving section 112.
The frame transmitting/receiving section 112 also receives the IP packet and control information contained in the frame from the radio access control section 12, and outputs the IP packet to the QoS function section 111 in accordance with the control information.

In addition, the frame transmission/reception unit 112 outputs the identifier of the communication station of the received frame to the communication station quality management unit 114, inputs the aggregation amount and aggregation method corresponding to the communication station from the aggregation management unit 111a, outputs it to the wireless access control unit 12 and also to the communication station quality management unit 114.

[Communication method function unit 113]
The communication method function unit 113 controls switching of the communication method based on information from the control terminal 3 about the communication method and line status.
Specifically, when communication method instruction information instructing a communication method (access method) or a data carrier to be used for wireless communication is input from the dedicated control terminal 3, the communication method function unit 113 performs the following: The settings of the radio access control unit 12, radio signal processing unit 13, and high frequency unit 14 are switched in accordance with the input communication method instruction information. Each unit of this communication device has setting information prestored therein that corresponds to a plurality of communication methods. There is something.

Furthermore, the communication method function unit 113 calculates a communication capacity (transmission capacity) according to the determined communication method, and notifies the radio access control unit 12 of the calculated capacity.
The communication capacity may be stored in advance in association with the communication method, or may be calculated.

[Communication station quality control section 114]
The communication station quality management unit 114 acquires the identifier of the communication station of the received frame from the frame transmission/reception unit 112, acquires the number of frames transmitted and received for each communication station from the transmission/reception counter 121 in the wireless access control unit 12, and acquires the signal quality from the signal quality acquisition unit 114. The communication quality information for each communication station is acquired from 122, and is stored and managed as a database.
Furthermore, the communication station quality management unit 114 outputs communication quality information and the number of transmitted and received frames for each communication station in response to a request from the aggregation management unit 111a.

[Characteristic processing in this communication device: Figures 2 to 4]
Next, the characteristic processes in the communication device 1 will be described with reference to Figures 2 to 4. Figure 2 is a schematic diagram showing the configuration of a transmission/reception frame and upper protocol data, Figure 3 is a diagram showing an example of communication quality information, and Figure 4 is a diagram showing an example of communication method information.
In FIG. 2, the first row shows a "WLAN Frame (QoS Frame)", the second row shows an "IP Packet", the third row shows a "TCP Segment", and the fourth row shows a "UDP Segment".

The aggregation management unit 111a in the QoS function unit 111 of the network unit 11 of the communication device 1 inputs a frame received by the antenna 5 from the frame transmission/reception unit 112, and acquires the identifier of the communication station.
The identifier is obtained from the "Source MAC Address" of the "WLAN Frame (QoS Frame)" in the first row of FIG.
This identifier is uniquely set when a communication station is started, and is not dynamically changed or overlapped between communication stations.

Then, the communication station quality management unit 114 of the network unit 11 acquires communication quality information from the signal quality acquisition unit 122 in the radio access control unit 12 at the timing of frame reception.
The communication quality information includes information as shown in Fig. 3. In the example of Fig. 3, RSSI (Received Signal Strength Indicator): received signal strength, number of received subcarriers: number of effective subcarriers per one symbol upon reception, and equalization error: total compensation value when symbols are compensated by an equalizer taking into account frequency characteristics are shown, but other communication quality information may be used.

The communication station quality management unit 114 manages the communication quality information as a database in a form capable of holding multiple records for each communication station identifier.
The communication station quality management unit 114 also obtains the number of frames transmitted and received from the transmission/reception counter 121 in the radio access control unit 12, and adds it to the communication quality information.
That is, the communication station quality management unit 114 manages communication quality information and the number of transmitted and received frames for each communication station.

The aggregation management unit 111 a also receives the communication method information shown in FIG. 4 transmitted by the control terminal 3 via the communication method function unit 113 .
As shown in FIG. 4, the communication method information includes an access method, a modulation method, the number of transmission subcarriers, an encryption method, and the like.

The access method includes CSMA, TDMA, WTRMA (Wireless Token Ring Multiple Access: an access control method by token exchange between wireless devices), and the like, as multiple access methods in wireless space.
The modulation method is a multi-level modulation method using one symbol, and includes adaptive modulation, BPSK, QSK, 16QAM, and the like.
The number of communication subcarriers per symbol may be 24 subcarriers, 48 subcarriers, or the like.
Encryption methods include AES256+GCM, AES128+CBC, etc.

In addition, the control terminal 3 transmits the "Type of Service" in the "IP Packet" in Figure 2 to the aggregation management unit 111a as priority information, and the aggregation management unit 111a also manages the priority information.

Then, at any timing, the aggregation management unit 111a acquires quality information for each communication station and the number of frames sent and received from the communication station quality management unit 114, and determines the aggregation amount and aggregation method for the relevant communication station by referring to the communication method information and priority information from the communication method function unit 113.

[Aggregation amount determination process: Figures 5 and 6]
Next, the process of determining the amount of aggregation will be described with reference to Figs. 5 and 6. Fig. 5 is a flow diagram showing the process of determining the amount of aggregation (1), and Fig. 6 is a flow diagram showing the process of determining the amount of aggregation (2). Figs. 5 and 6 are a series of processes, but will be described separately. Therefore, they are linked at (A) in each figure.
The aggregation amount is determined by the aggregation management unit 111a.

[Aggregation amount determination process (1): FIG. 5]
As shown in FIG. 5, first, the maximum transmission size of the line is calculated from the communication method information.
For example, in the case of the communication method shown in Fig. 4, the maximum transmission size (MTU) is calculated according to the encryption method. This is because the amount of control information to be added increases or decreases due to differences in block length and other factors depending on the algorithm or method.
First, MTU information corresponding to the encryption method is obtained (S11).

Then, the maximum aggregation amount is set as AGFmax, and is calculated from the MTU and the maximum frame aggregation size (AgNum) (S12).
The formula is AGFmax = MTU * AgNum.

Next, check the access method.
This is because in the case of TDMA, WTRMA, etc., there is a limit to the size of a frame that can be transmitted in one transmission opportunity. This maximum frame size (ACmax) is obtained (S13).
At this time, it is determined whether ACmax is equal to or greater than AGFmax (ACmax ≦ AGFmax) (S14). If ACmax is equal to or greater than AGFmax (YES), the process proceeds to the next step, and if ACmax is less than AGFmax (NO), AGFmax is updated to ACmax [AGFmax = ACmax] (S15).

Then, a calculation is performed based on the number of transmitted subcarriers.
A usage rate (SCrate) is calculated from the amount of transmitted subcarriers (SCcurrent) relative to the maximum number of subcarriers in use (SCmax) of this communication device 1 (S16).
This is done by division with SCmax. The formula is SCrate=SCcurrent/SCmax, where 0<SCrate≦1.

Then, the maximum aggregation amount is updated based on the subcarrier usage rate (S17).
Specifically, the result of multiplying the SCrate calculated in step S16 by AGFmax is updated to the new AGFmax by the formula AGFmax = AGFmax * SCrate.

[Aggregation amount determination process (2): FIG. 6]
Similarly to the above, calculations are now performed using information from the receiving station.
6, the utilization rate RCrate is calculated from the amount of subcarriers received from the receiving station RCcurrent (S21). The calculation method is the same as that for the subcarrier information described above.
Also, the maximum aggregation amount (AGFrcm) is calculated based on the subcarrier usage rate (S22), using the formula AGFrcm = AGFmax * RCrate.

Then, it is determined whether the aforementioned AGFmax is equal to or less than AGFrcm (AGFmax ≦ AGFrcm) (S23). If AGFmax is equal to or less than AGFrcm (YES), the process proceeds to the next step. If AGFrcm is smaller than AGFmax (NO), AGFmax is updated to the value of AGFrcm [AGFmax = AGFrcm] (S24).

Finally, the equalization error is checked. The equalization error is converted into dB, and the received CNR (Carrier-to-Noise Ratio) current is estimated from the difference with the mapping power (S25). This is because, as the noise component increases, the amount of equalization increases, resulting in an increase in error.
That is, if the error is large, the CNRcurrent of the symbol is poor (small), and if the error is small, the CNRcurrent is large.

A modulation scheme derived from this CNRcurrent is selected.
The optimum modulation method Moda is calculated so that 0<Modmin≦Moda≦Modmax, and Mrate is calculated with Modmax as the denominator (S26). The calculation formula is Mrate=Moda/Modmax.

Then, the multiplication result of the calculated Mrate and the aforementioned AGFmax is set as the frame aggregation amount (AGFmax) [AGFmax = AGFmax * Mrate] (S27), and the processing is terminated.

[Aggregation method determination process: FIG. 7]
Next, the process of determining an aggregation method will be described with reference to Fig. 7. Fig. 7 is a flow diagram showing the process of determining an aggregation method.
Incidentally, the process of determining the aggregation method is also performed by the aggregation management unit 111a, but it may be arranged for the communication method function unit 113 to perform this process.
First, the above-mentioned received NRcurrent is registered in the CNR list (CNRList) (S31).

If the number of entries in the CNRList is equal to or greater than the prescribed number (YES), averaging is performed (S33).
The arithmetic average (CNRavg(t)) is calculated by adding CNRcurrent multiplied by the weighting coefficient λ and CNRagv(t-1) multiplied by (1-λ) minus the weighting coefficient.
The calculation formula is CNRavg(t)=λ*CNRcurrent(t)+(1−λ)*CNRagv(t−1).

Also, if the CNRList does not meet the specified number (NO), the normal average is calculated (S34).

Next, the standard deviation δ of the CNR is calculated with respect to the average (S35).
The standard deviation δ is calculated as the square root of the covariance of the sum of the subtracted CNRavg from each CNR registered in the CNRList and squared.

Then, for the calculated standard deviation δ, the relationship between the threshold value δcnm and the maximum deviation δcm is determined (S36).
Specifically, if δ exceeds δcnm (δ ≧ δcnm), the line quality with the destination communication station is deemed unstable and the MPDU (MAC protocol data unit) method, which provides a stronger synchronization signal, is used (S37). If δcns < δ < δcnm, the A-MPDU (aggregation MAC protocol data unit) method is used (S38). If δ ≦ δcns, the A-MSDU (aggregation MAC service data unit) method is used (S39).

In this manner, the frame aggregation method is determined.
The frame aggregation method may be changed based on priority information set from the control terminal 3 .

In this way, appropriate frame aggregation is realized for each communication station in the communication device 1, so that lines are not monopolized by malicious communications and malicious communications can be easily detected and blocked.

[Effects of the embodiment]
According to the present communication device 1, the communication station quality management unit 114 acquires an identifier of the communication station from the received frame, acquires communication quality information from the signal quality acquisition unit 122 at the time of receiving the received frame, and further acquires the number of frames transmitted and received for each communication station from the transmission and reception counter 121. The aggregation management unit 111a determines the aggregation amount and aggregation method for the corresponding communication station based on the quality information for each communication station from the communication station quality management unit 114, the number of frames transmitted and received, and the communication method information from the communication method function unit 113, thereby realizing appropriate frame aggregation. This has the effect of avoiding unnecessary line occupation and making it easier to detect and block malicious communications.

The present invention is suitable for communication devices and communication systems that can achieve appropriate frame aggregation in wireless network conditions, avoid unnecessary line occupation, and detect and block malicious communications.

111, 112, 113, and 114
Reference Signs List 1, 10... communication device, 2... communication terminal, 3, 30... control terminal, 5... antenna, 6..., 7..., 8..., 9..., 10..., 11, 110... network unit, 12, 120... radio access control unit, 13, 130... radio signal processing unit, 14, 140... radio frequency unit, 111... QoS function unit, 111a... aggregation management unit, 112... frame transmission/reception unit, 113... communication method function unit, 114... communication station quality management unit, 121... transmission/reception counter, 122... signal quality acquisition unit

Claims (6)

A communication device used in a wireless network in which a plurality of wireless stations have autonomous distributed access,
A communications device that acquires an identifier of the wireless station from a received frame, acquires communication quality information at the time of receiving the received frame, and further acquires information on the number of frames transmitted and received and the communication method for each wireless station, and determines the aggregation amount and aggregation method for the corresponding wireless station based on the quality information, the number of frames transmitted and received, and the communication method for each wireless station, and changes the aggregation method for linking communication frames. The communication device according to claim 1, which determines the number of effective subcarriers of a signal to be transmitted and received, and changes the amount of aggregation by changing the number of frames to be linked according to the number of effective subcarriers. The communication device according to claim 1, which judges communication quality from the equalization error of the transmitted and received signals, selects an optimal modulation method according to the communication quality, and changes the aggregation amount by changing the number of frames to be linked according to the selected modulation method. The communication device according to claim 1, which judges communication quality from the signal-to-noise ratio of a signal received from a wireless station and changes the aggregation method for linking frames according to the communication quality. The communication device according to claim 1, which determines priority information of wireless stations present within a communication range and changes the aggregation method according to the priority information. A communication system comprising the communication device according to any one of claims 1 to 5 .

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