JP4963585B2 - COMMUNICATION DEVICE AND COMMUNICATION METHOD, PROGRAM, AND STORAGE MEDIUM - Google Patents

Description

The present invention relates to a communication device, a control method for communication , a program, and a storage medium.

Products corresponding to the IEEE standard (Non-Patent Document 1), which is a standard for wireless LAN devices, are widely used. In recent years, the concept of QoS (Quality of Service) has been introduced in wireless data transmission communications, and the IEEE 802.11 working group TGe is studying to guarantee priority and bandwidth according to data contents and usage. . The following communication methods have been proposed for the wireless LAN standard incorporating this QoS function.
-HCCA method (non-competing communication method) that can use the wireless communication band without contention.
-EDCA method (competitive communication method) used in competition with other wireless terminals.
-HEMM method that uses both HCCA method and EDCA method.
However, EDCA is an abbreviation for Enhanced Distributed Channel Access, and HCCA is an abbreviation for HCF (Hybrid Coordination Function) Controlled Channel Access.

Patent Document 1 discloses a method for improving communication efficiency by switching between the HCCA method and the EDCA method.
JP 2006-148580 A IEEE Std 802.11-1999 (R2003) IEEE P802.11e / D12

  When a wireless LAN terminal communicates data that requires a wide band, such as a video signal, with a non-competitive HCCA system to secure the necessary bandwidth, it is always necessary to communicate with other terminals. Bandwidth will decrease. In some cases, there may be no bandwidth available for other terminals. For this reason, the malfunction that wireless LAN communication of another terminal cannot be performed occurs.

  In addition, when broadband data encoded by a video encoding method such as MPEG2 is communicated by an EDCA method that is a competing method, a necessary band is not always ensured depending on the availability of the communication band. For this reason, data transmission is sometimes delayed due to insufficient bandwidth, and underrun of received data occurs on the receiving side. Also, to prevent this underrun, discarding delayed data deletes data such as MPEG2 I-pictures and uses not only those I-pictures but also P-pictures and B-pictures that refer to those I-pictures become unable. Therefore, image disturbance occurs for a long time.

  The present invention has been made in view of the above problems, and when there are other devices that use communication resources, the device itself and other devices perform appropriate data transfer by appropriately using the communication resources. The purpose is to provide technology that enables

A communication device for controlling communication of another communication device,
Receiving means for receiving a communication band allocation request for communicating first data or second data having higher importance than the first data from the other communication device;
In response to the communication bandwidth allocation request, a communication method for communicating the second data is set to a non-contention method, and a bandwidth that can be used by the communication device and an amount of traffic that the communication device should transmit or receive And setting means for selecting and setting a communication method for communicating the first data from a non-competing communication method and a competing communication method,
Have

According to the present invention, when there are a plurality of devices that use communication resources, communication when communicating at least second data having higher importance than the first data to a device that has requested a communication band. The system is set to the non-competing system, and the communication system for communicating the first data is set to either the non-competing communication system or the competing communication system according to the capacity of the communication band. For this reason, among the data transmitted from the device that has requested the communication band, important second data can be stably communicated, while the first data is moved according to the communication status of other devices. Therefore, communication is performed with an allocated bandwidth. Therefore, a technique for reducing a problem that communication with other devices cannot be performed while reducing communication delay in a device that has requested a communication band, and enabling a plurality of devices to perform appropriate data transfer. Can be provided.

  Embodiments according to the present invention will be described below in detail with reference to the accompanying drawings. However, the constituent elements described in this embodiment are merely examples, and are not intended to limit the scope of the present invention only to them.

<< First Embodiment >>
(Communications system)
First, the configuration of a wireless LAN communication system including the communication method according to the present embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration of a wireless LAN communication system including a communication device according to the present embodiment.

  In FIG. 1, 101 is an access point QAP1 having a wireless LAN function and a wired LAN function, 102 is a camera QSTA1 having a wireless LAN function, and 103 is a personal computer 1 (QSTA2) having a wireless LAN function. Reference numeral 104 denotes a display 1 (QSTA3) having a wireless LAN function, 105 denotes a personal computer 2 having a wired LAN function, and 106 denotes a display 2 having a wired LAN function.

  The access point QAP1 (101), the personal computer 2 (105), and the display 2 (106) are connected by a LAN and can transmit / receive IP frame data to / from each other. LAN specifications are standardized by the IEEE802.3 working group, and this communication system is connected by a method called 100BASE-TX having a communication speed of 100 Mbps. Further, the access point QAP1 (101) has a wireless LAN function standardized by the IEEE802.11 working group, and enables mutual communication between terminals on the wireless LAN side and the wired LAN side. The camera QSTA1 (102), the QSTA2 (103) of the personal computer 1 and the QSTA3 (104) of the display 1 also each have a wireless LAN function standardized by IEEE802.11.

  The wireless LAN standardized by IEEE802.11 defines various extended functions such as IEEE802.11b, IEEE802.11g, IEEE802.11a, and IEEE802.11e. The wireless LAN of this communication system has an extended function of IEEE802.11a and IEEE802.11e. IEEE802.11a is a wireless LAN specification using the 5 GHz band, and specifies a communication rate up to 54 Mbps. IEEE802.11e supports QoS that is an extension of the existing MAC. Note that the access point QAP1 (101) and each wireless LAN terminal also have an extended function according to this embodiment.

  The camera QSTA1 (102) converts the video signal into encoded data, and wirelessly transmits the encoded data via the access point QAP1 (101). The personal computer 1 (QSTA2, 103) and the personal computer 2 (105) can store the encoded data received in the built-in hard disk, or can decode and display the video data.

  The personal computer 1 (QSTA2, 103) can wirelessly transmit the encoded data stored in the built-in hard disk via the access point QAP1 (101). Similarly, the personal computer 2 (105) can wirelessly transmit the encoded data stored in the built-in hard disk via the access point QAP1 (101). The display 1 (QSTA3, 104) and display 2 (106) receive the encoded data transmitted from the camera QSTA1 (102), personal computer 1 (QSTA2, 103), personal computer 2 (105), and receive the video signal. Can be decoded and displayed.

  In the present embodiment, the details of the configuration according to the present embodiment will be described on the assumption that the camera QSTA1 (102) transmits encoded data of a captured video and displays it on the display 2 (106).

(Camera configuration)
Next, the configuration of the camera QSTA1 (102) will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the camera QSTA1 (102) according to this embodiment.

  In FIG. 2, 201 is a control unit that controls the operation of the entire camera, 202 is a camera unit that captures video and generates a video signal, and 203 is a code that compresses the video signal in the MPEG2 format to generate encoded data. Part. 204 is a storage unit for temporarily storing the encoded data, 205 is a data separating unit for separating the encoded data into basic data or extended data 1 or extended data 2, and 206 is a basic data temporarily stored in FIFO format. This is a basic data queue that is memorized. 207 is an extended data queue 1 that temporarily stores the extended data 1 in the FIFO format, 208 is an extended data queue 2 and 209 that temporarily stores the extended data 1 in the FIFO format, and 209 is a wireless LAN function. This is a wireless communication unit to be realized.

(MPEG2 encoding system)
Here, the MPEG2 encoding method will be described with reference to FIG. FIG. 5 is a diagram schematically showing a frame configuration according to the MPEG2 system. MPEG2 is a video compression algorithm recommended by ISO. As shown in FIG. 5, the MPEG2 encoding system handles 15 frames of video in units of data called one GOP (Group of Picture). Each frame in the GOP is one of an I picture (Intra Picture), a P picture (Predictive Picture), and a B picture (Bidirectionally Picture), and is encoded by a different method.

  The I picture is independent of the preceding and succeeding pictures, and all video signals are intra-frame encoded using the DCT (Descrete Cosine Transform) method. P pictures are generated by performing forward predictive coding from past I pictures. The B picture is encoded by bidirectional prediction from past and future I pictures or P pictures.

  Therefore, even if the B picture data is lost, the I picture and the P picture can be reproduced. Even if a P picture is missing, an I picture can be reproduced. In other words, the I picture has the highest importance as the data, the next highest is the P picture, and the lowest importance is the B picture. The more important pictures are missing, the greater the degradation of the quality of the reproduced image.

  Further, time information for synchronous reproduction such as PTS (Presentation Time Stamp) and DTS (Decoding Time Stamp) is added to the data of each picture. For this reason, even if each picture is sent to the playback side of the image through a separate communication path and arrives in a different order, the playback side can rearrange it in the original frame order from the time information of PTS and DTS. Therefore, it can be played back in the original frame order. Note that PTS is time information indicating a reproduction time, and DTS is time information indicating a decoding time.

  The encoded data output from the encoding unit 203 is stored in the storage unit 204. When the communication line is not connected, the control unit 201 stores the encoded data of the captured video in the storage unit 204, and when the communication line is connected, the control unit 201 stores the encoded data stored in the storage unit 204. Read out and transfer to the separation unit 205.

  The data separation unit 205 has a function of separating the read encoded data bit stream into the I picture, the P picture, and the B picture. As for the separated data, the I picture is stored in the basic data queue 206, the P picture is stored in the extended data queue 1 (207), and the B picture is stored in the extended data queue 2 (208).

(Access point configuration)
Next, the configuration of the access point QAP1 (101) will be described with reference to FIG. FIG. 3 is a block diagram showing the configuration of the access point QAP1 (101) according to this embodiment.

  In FIG. 3, 301 is a wireless communication unit that realizes a wireless LAN function, 302 is a storage unit that accumulates received data until transfer is completed, 303 is a LAN communication unit that realizes a wired LAN function, and 304 is It is a control part which controls the whole operation | movement of this access point.

  Access point QAP1 (101) temporarily stores data received by wireless communication unit 301 or LAN communication unit 303 in storage unit 302, and transmits from wireless communication unit 301 or LAN communication unit 303 according to destination information added to the data. . Furthermore, the wireless communication unit 301 controls the QoS control function under the control of the control unit 304, and mixes both EDCA mode for EDCA communication, HCCA mode for HCCA communication, and both EDCA and HCCA methods. The mediation function of the HEMM mode to be used is realized.

  When the transmission rate of data to be communicated can be adaptively changed, the access point QAP1 (101) and the wireless LAN terminal according to the present embodiment set the connection of the traffic stream in the HEMM mode. At this time, the wireless LAN terminal notifies the access point QAP1 (101) of the minimum required minimum transmission band and the maximum possible maximum transmission band. The access point QAP1 (101) calculates the maximum value and the minimum value of the transmission time from the notified minimum transmission band and maximum transmission band. Then, the transmission time in the HCCA mode is adaptively changed between the minimum value and the maximum value according to the state of the communication line. In other words, when there is enough room to use the communication line exclusively, the transmission time corresponding to the maximum transmission band is transmitted in the HCCA mode. Conversely, when there is no margin in the communication line, the transmission time corresponding to the minimum transmission band is transferred in the HCCA mode, and the remaining data is transferred in the EDCA mode. Furthermore, the HCCA mode time is changed stepwise between the transmission time of the minimum transmission band and the transmission time of the maximum transmission band according to the margin of the communication line. In this way, the ratio between the HCCA mode and the EDCA mode is adaptively changed.

(Display configuration)
The display 2 (106) will be described with reference to FIG. FIG. 4 is a diagram showing the configuration of the display 2 (106) according to the present embodiment.

  In FIG. 4, 401 is a control unit that controls the overall operation of the display, and 402 is a LAN communication unit that implements a wired LAN function. 403 is a basic data queue for temporarily storing basic data in FIFO format, 404 is extended data queue 1 for temporarily storing extended data 1 in FIFO format, and 405 is an extended data 2 in FIFO format. The extended data queue 2 is temporarily stored. Reference numeral 406 denotes a data assembling unit that assembles encoded data separated into basic data, extension data 1 and extension data 2 into a continuous data stream. Reference numeral 407 denotes a storage unit for storing the data stream. Reference numeral 408 denotes a decoding unit that decodes the stream data read from the storage unit using the MPEG2 method and converts the data into a video signal. Reference numeral 409 denotes a display unit that draws and displays the video signal on the screen. Although not shown, the display 2 (106) includes operation input means for performing various settings and operation control by user operations.

(Traffic stream settings)
Next, traffic stream setting by the wireless communication unit 209 and the like will be described with reference to FIG. FIG. 6 is a sequence chart showing a traffic stream setting procedure.

  The access point QAP1 (101) of this embodiment is always turned on and operating, is connected to a LAN that is a wired network, and is also operating as a wireless LAN access point. The display 2 (106) is also turned on and connected to the LAN. Assume that the camera QSTA1 (102) is turned on (601). In this case, the wireless communication unit 209 of the camera performs Authentication (602) as an authentication procedure and Association (603) as a connection procedure to the network with respect to the access point QAP1 (101). Thereby, it connects to LAN via access point QAP1 (101).

  When the camera QSTA1 (102) is connected to the LAN and the operator next searches the connected device by operating the display 2 (106), the camera QSTA1 (102) added earlier is detected on the network. . Therefore, it is assumed that the operator further operates (604) so as to set the connection with the camera QSTA1 (102) by operating the display 2 (106). In this case, the display 2 (106) mutually acquires connection information (605, 606) such as communication capability and encoding capability with the camera QSTA1 (102) via the access point QAP1 (101).

  Through this connection information acquisition processing (605, 606), the cameras QSTA1 (102) and the display 2 (106) identify that the TSID of the identification information for identifying the traffic stream to be communicated is common. However, TSID is an abbreviation for Traffic Stream Identifer. Further, it is identified that three data having different priorities are transmitted from the camera QSTA1 (102). Then, each identified item is set.

  Then, the camera QSTA1 (102) first sets the traffic stream of the most important data in the access point QAP1 (101) by the ADDTS Request (607). In the example of the present embodiment, the most important data is I picture data stored in the basic data queue 206. Further, the traffic stream of the data with the highest importance requires setting of the HCCA mode in which the communication band is periodically guaranteed. When the access point QAP1 (101) understands the setting of the traffic stream, it returns an ADDTS Response 608 to the camera QSTA1 (102).

  The camera QSTA1 (102) then sets the traffic stream of the second most important data to the access point QAP1 (101) by the ADDTS Request (609). The TSID at this time is set with the same value as that of the I picture. In the example of this embodiment, the second most important data is P picture data stored in the extended data queue 1 (207). The traffic stream of the second most important data requires setting of the HEMM mode that can communicate in either the EDCA mode or the HCCA mode. When the access point QAP1 (101) understands the setting of the traffic stream, it returns an ADDTS Response 610 to the camera QSTA1 (102).

  Further, the camera QSTA1 (102) sets the setting of the traffic stream of the least important data to the access point QAP1 (101) by the ADDTS Request (611). The TSID at this time is set with the same value as that of the I picture. In the example of this embodiment, the least important data is B picture data stored in the extended data queue 2 (208). For this data traffic stream, it is required to set the HEMM mode that can communicate in either EDCA mode or HCCA mode. When the access point QAP1 (101) understands the setting of the traffic stream, it returns an ADDTS Response 612 to the camera QSTA1 (102).

(Data transmission scheduling)
When QAP1 (101) is requested to set up multiple traffic streams (TS) with the same TSID, QAP1 (101) sets the priority of data previously set in ADDTS Request to the priority of data set later. Schedule with higher priority. Further, the schedule based on the priority of QAP1 (101) according to the present embodiment is controlled based on the number of traffic streams (TS) other than the other HCCA modes set in the access point QAP1 (101). HEMM mode counts as other than HCCA. The schedule based on this priority is as shown in the table of FIG. FIG. 10 is a diagram illustrating an example of communication mode allocation according to data priority.

  In FIG. 10, basic data (1001) is I picture data accumulated in the basic data queue 206. The extension data 1 (1002) is P picture data stored in the extension data queue 1 (207), and the extension data 2 (1003) is B picture data stored in the extension data queue 2 (208). is there. The number of TSs is the number of TSs that the access point QAP1 (101) has set for connection in a mode other than the HCCA mode, and is classified when there are 1 or less, 2 or 3 or more. When there are multiple traffic streams with the same TSID, they are counted as separate TSs. TXOP Limit (1004) is an information element that notifies the upper limit of the time allowed to transmit in HCCA mode to the terminal to which access point QAP1 (101) is connected.

  When the number of other TSs connected to the access point QAP1 (101) is one or less, the basic data, the extended data 1 and the extended data 2 are all transferred in the HCCA mode. The data transmission order on the camera QSTA1 (102) side is that the basic data is first, the extension data 1 is transferred next, and the extension data 2 is finally transferred according to the importance of the data. The value of TXOP Limit at this time is set by calculating time TXOP1 required for transmitting all of the basic data, extension data 1 and extension data 2 within the HCCA polling cycle. However, TXOP1 is calculated from the wireless transmission rate set between the access point QAP1 (101) and the camera QSTA1 (102) and the HCCA polling period.

  When there are two other TSs connected to the access point QAP1 (101), the basic data and the extended data 1 are transferred in the HCCA mode, and the extended data 2 is transferred in the EDCA mode. Similarly to the above, the data transmission order on the camera QSTA1 (102) side is that the basic data is the first, the extension data 1 is transferred next, and the extension data 2 is transferred last, according to the importance of the data. The value of TXOP Limit at this time is set by calculating time TXOP2 required for transmitting basic data and extension data 1 within the HCCA polling cycle from the wireless transmission rate that has been set for connection and the HCCA polling cycle.

  When there are three or more other TSs connected to the access point QAP1 (101), the basic data is transferred in the HCCA mode, and the extended data 1 and the extended data 2 are transferred in the EDCA mode. Similarly to the above, the data transmission order on the camera QSTA1 (102) side is that the basic data is the first, the extension data 1 is transferred next, and the extension data 2 is transferred last, according to the importance of the data. The value of TXOP Limit at this time is set by calculating the time TXOP3 required to transmit basic data within the HCCA polling cycle from the wireless transmission rate that has been set for connection and the cycle of HCCA polling.

(data transfer)
Next, the state of data transfer according to the present embodiment will be described in detail with reference to FIG. 7, FIG. 8, and FIG. FIG. 7 is a diagram showing a state of data transfer when there is one (two in total) other traffic streams connected to QAP1 (101). One is an upstream traffic stream between the access point QAP1 (101) and the camera QSTA1 (102), and the other is a downstream traffic stream between the access point QAP1 (101) and the display 1 (QSTA3, 104). It is.

  QAP1 (101) transmits a polling signal in which the time required to transfer all of the basic data and the extended data 1 and 2 in the HCCA mode is transmitted to QSTA1 (102) at the timing of the HCCA cycle. Here, as a polling signal, QoS + CF-Poll (701) in which the time required for transfer in the HCCA mode is set in the information element TXOP Limit is transmitted. The TXOP Limit here is a maximum occupation period in which the camera QSTA1 (102) is preferentially permitted to transfer data, and the TXOP Limit value to be set is the value of the TXOP1.

  When the camera QSAT1 (102) receives QoS + CF-Poll (701), it determines that a transmission opportunity during the TXOP period 702 calculated from the value of TXOP1 is given. Therefore, according to the priority of data, first, basic data is transmitted (703), then extended data 1 is transmitted (704), and finally extended data 2 (705) is transmitted.

  When the transmission (705) of the extended data 2 that is the final data of the HCCA period is completed, the QAP 101 determines that the HCCA period (706) has ended, and determines the remaining period up to the timing of the next HCCA period as the EDCA period (707). Judge. During the EDCA mode period (707), communication with other terminals accessing in the EDCA mode is performed. The example of FIG. 7 shows a state where QAP1 (101) and display 1 (104) are performing wireless transmission (715, 716) of the traffic stream in the EDCA mode.

  Then, at the timing of the next HCCA cycle, QAP1 (101) again sets the time required to transfer all of the basic data and the extended data 1 and 2 to the QSTA1 (102) in the HCCA mode. 708). Again, the polling signal is QoS + CF-Poll with time set in TXOP Limit. In the same manner as described above, transmission of basic data (710), transmission of extension data 1 (711), and transmission of extension data 2 (712) are executed. Thereafter, the same operation is repeated every HCCA cycle.

  FIG. 8 is a diagram showing a state of data transfer when there are two (3 in total) other TSs connected to QAP1 (101). In addition to the upstream traffic stream (TS) between QAP1 (101) and QSTA1 (102), there are two traffic streams. That is, there are two EDCA mode uplink TSs between QAP1 (101) and QSTA2 (103) and EDCA mode downlink TSs between QAP1 (101) and QSTA3 (104).

  When QAP1 (101) reaches the timing of the HCCA cycle, polling signal QoS + CF- that sets the time required to transfer basic data and extension data 1 in HCCA mode to TXSTA Limit to QSTA1 (102) Send Poll (801). The value of TXOP Limit set at this time is the value of TXOP2.

  When QSAT1 (102) receives QoS + CF-Poll (801), it determines that a transmission opportunity is given only for the TXOP period 802 calculated from the value of TXOP2. Then, according to the priority of data, first, basic data is transmitted (803), and then extended data 1 is transmitted (804). Since the camera QSTA1 (102) ends the TXOP period, the remaining extension data 2 is transmitted (805) in the EDCA mode after the EDCA period. When QAP1 (101) completes transmission (804) of extension data 1 of QSTA1 (102), it determines that the HCCA mode period (806) has ended, and determines that it is the EDCA period (807) until the next HCCA cycle timing. To do.

During the period of EDCA mode (807), communication with a terminal accessing in EDCA mode is performed. In the example of FIG. 8, wireless communication is performed by the EDCA method while the following wireless transmissions compete with each other.
Wireless transmission of extension data 2 between the access point QAP1 (101) and the camera QSTA1 (102) (805, 812, 815).
-Wireless transmission (816, 819) between the access point QAP1 (101) and the personal computer 1 (103).
Wireless transmission (817, 818) between the access point QAP1 (101) and the display 1 (104).
In the EDCA period (807) of this embodiment, first, the QSTA2 (103) which is the personal computer 1 acquires the transmission right and transmits the data (816), and then the camera QSTA1 (102) acquires the transmission right. The extension data 2 is transmitted (805). Further thereafter, QSTA3 (104) as display 1 receives data from access point QAP1 (101).

  Then, at the timing of the next HCCA cycle, QAP1 (101) again polls QSTA1 (102) with a polling signal (808) that sets the time required to transfer basic data and extension data 1 in HCCA mode. Send. Again, QoS + CF-Poll with time set to TXOP Limit is transmitted as a polling signal. In the same manner as described above, basic data transmission (810) and extension data 1 transmission (811) are executed. When QAP1 (101) completes transmission of extension data 1 (811) of QSTA1 (102), it determines that the period of HCCA mode (813) has ended, and waits as the EDCA period (814) until the timing of the next HCCA cycle To do. Thereafter, the same operation is repeated every HCCA cycle.

  In the EDCA mode period (814) at this time, first, data transmission (818) from QAP1 (101) to QSTA3 (104) and transmission of extension data 2 from QSTA1 (102) to QAP1 (101) (812) Are colliding. As a result, data transmission (818) to QSTA3 (104) has acquired the transmission right, and transmission of extension data 2 from camera QSTA1 (102) (812) has failed. After that, QSTA2 (103) acquires the transmission right and transmits data (819), and then again, QSTA1 (102) tries to transmit extension data 2 to QAP1 (101) (815) Has been successful.

  If the transmission of the extension data 2 to the access point QAP1 (101) is not successful, the camera QSTA1 (102) repeats until the timing of the next HCCA cycle is within the extension data lifetime. If the lifetime of the extended data is exceeded or the timing of the next HCCA cycle is reached, the extended data 2 that failed to be transmitted is discarded.

FIG. 9 is a diagram showing a state of data transfer when there are three (four in total) other traffic streams connected to QAP1 (101). In addition to the upstream traffic stream between the access point QAP1 (101) and the camera QSTA1 (102), the following three traffic streams exist.
An EDCA mode upstream traffic stream and downstream traffic stream between the access point QAP1 (101) and the personal computer QSTA2 (103).
Downstream traffic stream in EDCA mode between access point QAP1 (101) and display 1 QSTA3 (104).

  When QAP1 (101) comes to the timing of the HCCA cycle, the time required to transfer basic data in HCCA mode to QSTA1 (102) is the QoS + CF-Poll of the polling signal set in the information element TXOP Limit Send (901). The value of TXOP Limit set at this time is the value of TXOP3. When QSAT1 (102) receives QoS + CF-Poll (901), it determines that a transmission opportunity is given only for the TXOP period (902) calculated from the value of TXOP3, and transmits basic data according to the priority of data (903 ) Since the camera QSTA1 (102) ends the TXOP period, the remaining extension data 1 transmission (904) and extension data 2 transmission (905) are transmitted in the EDCA mode after the EDCA period. When the basic data transmission (903) of QSTA1 (102) is completed, QAP1 (101) determines that the HCCA mode period (906) has ended, and determines that it is the EDCA period (907) until the timing of the next HCCA cycle .

During the period of EDCA mode (907), communication with a terminal accessing in EDCA mode is performed. In the example of FIG. 9, wireless communication is performed by the EDCA method while the following transmissions compete with each other.
Wireless transmission of extended data 1 (904, 911, 912) and wireless transmission of extended data 2 (905) between the access point QAP1 (101) and the camera QSTA1 (102).
-Wireless transmission between the access point QAP1 (101) and the personal computer 1 (103) (915, 916, 918, 920).
Wireless transmission (917, 919) between the access point QAP1 (101) and the display 1 (104).

  In the EDCA period (907) of this embodiment, the camera QSTA1 (102) first acquires the transmission right and transmits the extended data 1 (904), and then the personal computer 1 QSTA2 (103) acquires the transmission right. Then, data transmission (915) is performed. After that, QAP1 (101) starts data transmission (916) to QSTA2 (103). At this time, the camera QSTA1 (102) collides to start transmission and fails to transmit extended data 2 (905). Yes. Subsequently, the QAP (101) transmits data (917) to the QSTA3 (104) of the display 1, and the timing of the next HCCA cycle is reached. As a result, since QSTA1 (102) could not transmit (905) extension data 2 during the HCCA cycle, it discards extension data 2.

  Then, again at the timing of the next HCCA cycle, QAP1 (101) sends a polling signal (908) that sets the time required to transfer basic data in HCCA mode to camera QSTA1 (102). Yes. Again, as a polling signal, QoS + CF-Poll with the required time set in the information element TXOP Limit is transmitted. In the same manner as described above, transmission of basic data (910) is executed. When the basic data transmission (909) of QSTA1 (102) is completed, QAP1 (101) determines that the HCCA mode period (913) has ended, and again determines the EDCA period (914) until the timing of the next HCCA cycle. To do.

  In the EDCA period (914), the QAP1 (101) starts data transmission (918) to the QSTA2 (103) which is the personal computer 1. However, at this time, the camera QSTA1 (102) also collides to start transmission, and transmission of the extension data 1 (911) has failed. Subsequently, QAP1 (101) starts data transmission (919) to QSTA3 (104) which is display 1. However, at this time, the camera QSTA1 (102) collides again to start transmission, and the transmission of extended data 1 (912) fails. Note that the transmission of the extension data 2 is not started unless the transmission of the extension data 1 is completed. After that, QSTA2 (103), which is the personal computer 1, has acquired the right to transmit data and transmits (920) data to the access point QAP1 (101). After this, since the timing of the HCCA cycle is reached, the camera QSTA1 (102) eventually discards the extended data 1 and the extended data 2 without being transmitted.

  Through the operation described above, the I picture, P picture, and B picture generated by the encoding unit 204 of the camera QSTA1 (102) are separated into basic data, extension data 1, and extension data 2, respectively, and the wireless communication unit 209 is separated. Sent through. Then, it is received by the wireless communication unit 301 of the access point QAP1 (101) according to the above priority processing method, and transferred from the LAN communication unit 303 to the display 2 (106) connected to the LAN via the storage unit 302. .

  The display 2 (106) stores the data received by the LAN communication unit 402, the basic data is stored in the basic data queue 403, the extended data 1 is stored in the extended data queue 1 (404), and the extended data 2 is the extended data. Accumulate in queue 2 (405). The data assembling unit 406 then sends I, P from the basic data queue 403, the extended data queue 1 (404), and the extended data queue 2 (405) according to the decoding order of the DTS information added to each received picture data. , B picture data is read out. These data are reconstructed into a continuous data stream and stored in the storage unit 407. The encoding unit 408 reads the data stream from the storage unit 407, decodes the data stream using the MPEG2 method, converts the data stream into video data, and draws and displays the video on the display unit 409.

  As described above, the camera QSTA1 (102) transmits the most important basic data by the non-competing communication method. In addition, the data to be sent by the non-competing communication method is determined in order from the highest priority based on the QoS + CF-Poll signal, and the determined data is sent by the non-competing communication method, and other data Is transmitted by the competitive communication method. Therefore, among the data sent from the camera QSTA1 (102), the most important basic data is stably transferred, while other data is dynamically changed according to the communication status of other communication devices. Bandwidth is allocated to and transferred. Therefore, according to the configuration according to the present embodiment, when there are other devices that use communication resources, the own device and other devices can appropriately transfer data by appropriately using the communication resources. it can.

  In the above embodiment, the QoS + CF-Poll signal is used as the information indicating the policy related to the data transmission control. However, the present invention is not limited to this. That is, other signals can be used as long as they can be used as information indicating a policy related to data transmission control. In the above configuration, the QoS + CF-Poll signal indicates the time for sending data using the non-competing communication method, and the sending of data other than the basic data is controlled based on this time. I can't. For example, data transmission other than basic data may be controlled based on the amount of data transmitted in the non-competing communication system, the communication band in which data is transmitted in the non-competing communication system, or the like.

<< Second Embodiment >>
In the first embodiment, the TS setting is processed by ADDTS Request separately for each of the basic data, the extended data 1 and the extended data 2. However, all the data may be handled as one TS and the TS setting may be processed with one ADDTS Request. In this case, the TS setting process between the camera QSTA1 (102) and the access point QAP1 (101) is completed only by the ADDTS Request (607) and ADDTS Response (608) in FIG.

  At this time, the camera QSTA1 (102) requests TS in the HEMM mode. Here, the bandwidth necessary for transmitting the basic data having the highest importance is requested as the minimum value of the requested bandwidth in the HCCA mode, and is necessary for transmitting all of the basic data, the extended data 1 and the extended data 2. The bandwidth is requested as the maximum value of the requested bandwidth. That is, the bandwidth required for transmission of the extension data 1 and the extension data 2 is requested as a HEMM mode which may be either the HCCA mode or the EDCA mode. FIG. 11 is a diagram showing the state of this bandwidth request.

  In FIG. 11, T1 is a time required to transmit basic data and is calculated from a communication rate that can be connected to the requested bandwidth. T2 is a time required for transmitting the extended data 1, and is also calculated from a communication rate that can be connected to the requested bandwidth. T3 is a time required to transmit the extension data 2, and is also calculated from a communication rate that can be connected to the requested bandwidth. Therefore, since the time of T1 is always in HCCA mode and the time of T2 + T3 is in HEMM mode, the minimum value of TXOP that QAP (101) notifies with QoS + CF-Poll is T1, and the maximum value of TXOP is T1 + T2. + T3. QAP1 (101) decreases the TXOP value of QSTA1 (102) if there are many connection requests from other terminals, and increases the TXOP value if there are few connection requests from other terminals.

  The operation of the camera QSTA1 (102) when the QAP1 (101) operates as described above is as follows according to the TXOP value of QoS + CF-Poll notified from the QAP1 (101). First, when the value of TXOP is greater than or equal to T1 and less than or equal to T1 + T2, basic data is transmitted in HCCA mode, and extended data 1 and extended data 2 are transmitted in EDCA mode, as shown in FIG. . Next, when the value of TXOP is T1 + T2 or more and T1 + T2 + T3 or less, basic data and extension data 1 are transmitted in the HCCA mode, and extension data 2 is transmitted in the EDCA mode. When TXOP is equal to or larger than T1 + T2 + T3, basic data, extension data 1 and extension data 2 are transmitted in the HCCA mode.

  As described above, according to the configuration according to the present embodiment, TS setting can be performed by one ADDTS Request.

<< Third Embodiment >>
In the first embodiment, QSTA1 (102) includes a separate queue for each data importance level as a buffer for temporarily storing data to be transmitted. That is, a basic data queue (206) for basic data, an extended data queue 1 (207) for extended data 1, and an extended data queue 2 (208) for extended data 2 are provided. However, the basic data queue (206), the extended data queue 1 (207), and the extended data queue 2 (208) may be composed of one transmission data queue. In this case, it is possible to realize by storing each data with a label and identifying the data by the label at the time of reading.

  FIG. 12 is a diagram schematically showing the configuration of the transmission data queue. In FIG. 12, reference numeral 1201 denotes a transmission data queue. Reference numeral 1204 denotes I picture data accumulated in the transmission data queue 1201. 1205, 1206, 1208, and 1209 indicate B picture data stored in the transmission data queue 1201. Reference numerals 1207 and 1210 denote P picture data stored in the transmission data queue 1201. The transmission data queue 1201 is configured in a ring buffer format on a memory, writing is performed in the order of generation of picture data by the encoding unit 204, and reading is possible to read arbitrary data.

  When such a transmission data queue 1201 is used, the above-described separation unit 205 is not necessary. Instead, it is necessary to add a function of adding information on the data type (1202) for identifying whether it is an I picture, a P picture, or a B picture to the head of each picture data (1203). When this transmission data queue (1201) is used, the wireless communication unit 209 selectively reads out the picture data to be transmitted according to the data type information, and erases the picture data that has been read out for each picture.

  As described above, in this embodiment, each data is stored with a label, and the data is identified by the label at the time of reading. As a result, even if a single queue is used, by appropriately selecting the communication method according to the importance of the data, both the own device and other devices perform appropriate data transfer by appropriately using communication resources. It becomes possible.

<< Fourth Embodiment >>
In the first embodiment, the configuration in which the importance of data is divided according to the difference between an I picture, a P picture, and a B picture when the image encoding unit is the MPEG2 system has been described as an example. However, other classification methods may be applied.

  For example, in the case of the MPEG4 encoding method, a method called data partitioning is specified in which data in MB (Macro Block) is sent separately into motion vector information and texture information.

  FIG. 13 is a schematic diagram showing a configuration of MB data in the data partitioning method. In FIG. 13, reference numeral 1301 denotes a ResyncMarker which is a resynchronization signal when the decoding process is reprocessed due to an error or the like. 1302 is an MB Number, 1303 is a Quant Scale, and 1304 is a Header Extension Code. Reference numeral 1305 denotes data of motion vector information, and reference numeral 1306 denotes a motion marker indicating that the motion vector information ends and the texture information starts. Reference numeral 1307 denotes texture information data. The texture information 1307 is followed by the next MB ResyncMarker (1308).

  In such a data structure, since motion vector information is necessary for reproducing an image, basic data with high priority is used. Further, even if the transmission of the texture information fails, the reference macroblock indicated by the motion vector of the reference image can be substituted, so that the extension information is used. When such an MPEG4 encoding method is provided, the wireless communication unit transmits data from ResyncMarker to MotionMarker before as basic data in the HCCA mode. On the other hand, data after MotionMarker is transmitted as extension data in the HEMM mode.

  In another example, the method of this embodiment can be applied even when a hierarchical encoding method is used as the image encoding method. As such a hierarchical coding system, there are a coding system defined by the SNR Scalable profile defined by MPEG2 and a system such as JPEG200. The data based on the hierarchical encoding method includes data originally classified by importance. Therefore, according to the notified length of TXOP, important data is preferentially transmitted in HCCA mode, data that can be transmitted in HCCA mode is selected and transmitted in order of decreasing importance, and the remaining data is transmitted. Can be sent in EDCA mode.

  Furthermore, in the case where image data and audio data are sent simultaneously, the method of the present embodiment is used as basic data by increasing the importance of image data and as extended data by reducing the importance of audio data. You may apply.

  As described above, in the configuration according to the present embodiment, the data to be transmitted is appropriately classified according to the degree of importance, and the same method as the configuration according to the first embodiment is used. For this reason, not only MPEG2 data but also various data such as MPEG1, MPEG4, video data and audio data must be used appropriately for communication between the device itself and other devices using appropriate communication resources. Is possible.

<< Fifth Embodiment >>
In the first embodiment, transmission data is discarded when data transmission in the EDCA mode is not successful in the time of the HCCA cycle. However, the timing of discarding the transmission data may be when the frame head data of the next I picture or P picture is transmitted.

  A situation where such processing is required will be described with reference to FIG. FIG. 14 is a diagram illustrating a configuration of bit stream data output from the MPEG2 encoding unit. As shown in FIG. 14, since each B picture is predicted from the data of the previous and subsequent pictures, it is necessary to transmit the I picture and P picture, which are the prediction source data, to the decoding unit before the B picture. Therefore, the encoding unit generates a bit stream by changing the order of the I picture and the P picture as shown in FIG. The decoding unit that receives such a bitstream starts decoding the picture after receiving the data of each picture.

  Thus, for example, the B picture data received from Tb2 must be completed before the decoding of the P picture received from Tb3 starts, so the decoding of the B picture from Tb3 is completed. Start. That is, reception of the B picture starting from Tb2 must be completed by Tb3 when the P picture starts to be received. When the reception completion is delayed from Tb3, the subsequent picture decoding process is delayed, and the reproduced video is temporarily stopped. Further, there is a difference between the PTS time added to the data and the playback time on the decoding device side.

  In order to prevent such a video stop, it is necessary to discard the data that cannot be received before the decoding start time, and to reproduce the data of the next picture without delay. Therefore, the transmission side device detects when the PTS or DTS information added to the data of each picture indicating the frame head of each picture changes, and discards the data of the previous picture that has not been transmitted at the time of detection. To be able to. The data discarded at this time is the data stored in the extended data queue 1 (207) or the extended data queue 2 (208), and the PTS or DTS information having the same value as the frame of the picture that failed to be transmitted is added. What is necessary is just to discard the data. This makes it possible to prevent problems such as video stoppage and reproduction time shift.

<< Sixth Embodiment >>
Further, in the first embodiment, the TXOP time is controlled based on the number of traffic streams (TS) other than the other HCCA modes set in the access point QAP1 (101). However, the TXOP time may be controlled under conditions other than the number of TSs.

  For example, it is determined based on how busy the wireless line is due to communication using another wireless method such as IEEE802.11b or IEEE802.11g using the same frequency band, or communication using another access point using the same frequency band. May be. In this case, it is possible to decrease the TXOP value notified by QoS + CF-Poll when it is congested and increase the TXOP value notified by QoS + CF-Poll when it is not congested. .

  According to such a configuration, it is possible to appropriately select a communication method according to the purpose and purpose of communication and to appropriately share communication resources among a plurality of devices.

<< Other Embodiments >>
The exemplary embodiments of the present invention have been described in detail above. However, the present invention can take embodiments as, for example, a system, apparatus, method, program, or storage medium. Specifically, the present invention may be applied to a system composed of a plurality of devices, or may be applied to an apparatus composed of a single device.

  The present invention can also be achieved by supplying a program that realizes the functions of the above-described embodiment directly or remotely to a system or apparatus, and the computer of the system or apparatus reads and executes the supplied program code. Including the case where it is achieved.

  Therefore, since the functions of the present invention are implemented by a computer, the program code installed in the computer is also included in the technical scope of the present invention. That is, the present invention includes a computer program itself for realizing the functional processing of the present invention.

  In that case, as long as it has the function of a program, it may be in the form of object code, a program executed by an interpreter, script data supplied to the OS, and the like.

  Examples of the recording medium for supplying the program include the following. Namely, floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, MO, CD-ROM, CD-R, CD-RW, magnetic tape, nonvolatile memory card, ROM, DVD (DVD-ROM, DVD-) R) and the like are included.

  In addition, the following types of programs may be considered. That is, it is also possible to connect to a homepage on the Internet using a browser of a client device and download a computer program according to the present invention or a compressed file including an automatic installation function from the homepage to a recording medium such as an HD. It can also be realized by dividing the program code constituting the program according to the present invention into a plurality of files and downloading each file from a different homepage. That is, a WWW server that allows a plurality of users to download a program file for realizing the functional processing of the present invention on a computer is also included in the present invention.

  The following supply forms are also conceivable. That is, first, the program according to the present invention is encrypted, stored in a storage medium such as a CD-ROM, and distributed to users. Further, the present invention allows a user who has cleared a predetermined condition to download key information to be decrypted from a homepage via the Internet, execute a program encrypted by using the key information, and install the program on a computer. The structure which concerns on is implement | achieved. Such a supply form is also possible.

  In addition to realizing the functions of the above-described embodiments by the computer executing the read program, the following implementation modes are also assumed. In other words, based on the instructions of the program, the OS running on the computer performs part or all of the actual processing, and the functions of the above-described embodiments can be realized by the processing.

  Further, after the program read from the recording medium is written in the memory provided in the function expansion board inserted in the computer or the function expansion unit connected to the computer, the above-described embodiment is also based on the instructions of the program. The function is realized. That is, a CPU or the like provided in the function expansion board or function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

It is a figure which shows the structure of the wireless LAN communication system provided with the communication apparatus. It is a block diagram which shows the structure of camera QSTA1. 3 is a block diagram showing a configuration of an access point QAP1. FIG. It is the figure which showed the structure of the display. FIG. 3 is a diagram schematically showing a frame configuration according to an MPEG2 system. It is a sequence chart which shows the setting procedure of a traffic stream. It is the figure which showed the mode of the data transfer in case the other traffic stream connected to QAP1 is one. It is the figure which showed the mode of the data transfer in case the other traffic streams connected to QAP1 are two. It is the figure which showed the mode of the data transfer in case the other traffic streams connected to QAP1 are three. It is a figure which shows the example of communication mode allocation by the priority of data. It is a figure which shows the mode of a bandwidth request | requirement. It is a figure which shows the structure of a transmission data queue typically. It is a schematic diagram which shows the structure of MB data of a data partitioning system. It is a figure which shows the structure of the bit stream data output from the encoding part of MPEG2.

Claims (18)

A communication device for controlling communication of another communication device,
Receiving means for receiving a communication band allocation request for communicating first data and second data having higher importance than the first data from the other communication device;
In response to the communication bandwidth allocation request, a communication method for communicating the second data is set to a non-contention method, and a bandwidth that can be used by the communication device and an amount of traffic that the communication device should transmit or receive And setting means for selecting and setting a communication method for communicating the first data from a non-competing communication method and a competing communication method,
A communication apparatus comprising: The communication apparatus according to claim 1, wherein the amount of traffic is based on a number of communication paths connected to the communication apparatus. The communication device according to claim 1, wherein the amount of traffic is based on a number of communication devices connected to the communication device. The communication apparatus according to claim 1, wherein the amount of traffic is based on a time used for communication by a communication apparatus connected to the communication apparatus.   The communication device according to claim 1, wherein the setting unit notifies the other communication device of a time for communicating the second data in the non-competing communication method.   The communication apparatus according to claim 1, wherein the importance is determined based on an encoding method of the first data and the second data.   The communication apparatus according to claim 1, wherein a predetermined data unit is configured by the first data and the second data.   8. The communication apparatus according to claim 7, wherein the predetermined data unit is a GOP based on an MPEG encoding method.   The communication apparatus according to claim 1, wherein the first data is encoded based on the second data.   The first data is a P picture or a B picture encoded by an MPEG encoding method, and the second data is an I picture encoded by an MPEG encoding method. Item 10. The communication device according to any one of Items 1 to 9.   The said 1st data is the texture information by a data partitioning system, The said 2nd data is the motion vector information by a data partitioning system, The any one of Claim 1 thru | or 9 characterized by the above-mentioned. The communication device described.   6. The communication apparatus according to claim 1, wherein the first data is audio data, and the second data is image data.   13. The importance level of the first data and the second data is determined according to the order of reception of communication allocation requests related to the first data and the second data. The communication apparatus according to claim 1. A control method for communicating data between a communication device that controls communication of a terminal and the terminal,
The communication device receives a communication band allocation request for communicating first data and second data having higher importance than the first data from the terminal,
In response to the communication bandwidth allocation request, the communication device sets a communication method for communicating the second data to a non-contention method, and a bandwidth that can be used by the communication device and a transmission or reception by the communication device. A control method comprising: selecting and setting a communication method for communicating the first data from a non-competing communication method and a competing communication method in accordance with an amount of traffic to be performed.   15. The control method according to claim 14, wherein the terminal discards data that could not be communicated by any of the non-competing communication method and the competing communication method.   The program for functioning a computer as a communication apparatus of any one of Claims 1 thru | or 13.   A program for causing a computer to execute the control method according to claim 14 or 15.   A computer-readable storage medium storing the program according to claim 16 or 17.

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