JP2008072251A - Communication apparatus and its control method and program, and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for making it possible to utilize a channel in a short time upon resetting to normal operation mode when a communication apparatus performing communications by reserving a communication reservation band transits to a state where delivery of beacon information for specifying a communication reservation band is stopped, e.g. when the communication apparatus transits to power saving mode. <P>SOLUTION: The communication apparatus for performing wireless communications includes a means performing wireless communications with an external apparatus, and a control means for making the wireless communication means deliver beacon information including information for specifying a communication reservation band. When delivery of beacon information is stopped, the control means makes the wireless communication means deliver information for requesting the external apparatus to deliver beacon information for specifying a communication reservation band reserved by the communication apparatus before stopping delivery of the beacon information. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  In a wireless communication system forming a wireless network, power saving modes are defined by various standards. In the Wireless USB (WUSB, wireless USB) standard (Non-Patent Document 1), a power saving mode is defined for both the host and the device.

  In a communication system according to the same standard, a host and a device form a WUSB cluster, and communication is performed using a time division multiple access (TDMA) based superframe. Each superframe is composed of 256 Media Access Slots (MAS) of 256 μs, and only the beacon is transmitted as the first 16 MASs as a Beacon Period (BP). The remaining period is reserved for each cluster as a Distributed Reservation Protocol (DRP) which is a communication reservation band (communication available band). The period of DRP is indicated by the DRP Information Element (DRP IE) in the beacon transmitted from the host or device.

  The host and device synchronization management is performed in an independent and distributed manner, and the host has a function of performing superframe synchronization management. The host or device performs superframe synchronization adjustment by intercepting beacons other than itself. Devices are roughly classified into Self-beaconing Device (SBD) that performs superframe synchronization management by itself and Directed Beaconing Device (DBD) that does not perform superframe synchronization management by itself. The DBD can perform superframe synchronization management according to instructions from the host. For this purpose, the DBD has the following three functions: a count packet function for counting packets received by the DBD itself, a capture packet function for capturing a specific packet, and a transmit packet function for transmitting a specific frame. .

  In the WUSB standard, a plurality of WUSB clusters can exist, and they are allowed to overlap each other. A plurality of hosts and devices mutually perform synchronization and DRP reservation in a superframe. When only the host and the SBD exist, the host does not need to operate in the WUSB layer to establish synchronization.

When the DBD exists in the WUSB cluster, the host establishes synchronization with surrounding hosts / devices by causing the DBD to transmit a beacon using the transmit packet function in the WUSB layer.
Wireless USB Specifications 1.0

  Consider a situation in which a DBD exists in a WUSB cluster and a WUSB host enters a power saving mode in a communication system according to the WUSB standard. In such a case, if there are other WUSB clusters, there is a possibility that the DRP that has been reserved and used by the WUSB host will be occupied by other WUSB clusters. If the previously used DRP is occupied by another WUSB cluster, when the WUSB host returns from the power saving mode, the WUSB host must re-reserve the DRP from the initial state, It cannot be used.

  The present invention has been made in view of the above problems, and stops transmitting beacon information specifying a communication reserved band in a communication apparatus that performs communication by reserving a communication reserved band, such as when the communication apparatus shifts to a power saving mode. It is an object of the present invention to provide a technique that makes it possible to use a channel in a short time when returning to a normal operation mode when shifting to a state in which it is performed.

In order to achieve the above object, a communication apparatus according to the present invention comprises the following arrangement. That is,
A communication device for performing wireless communication,
Wireless communication means for performing wireless communication with an external device;
Control means for causing the wireless communication means to transmit beacon information including information designating a communication reserved band;
With
The control means includes
When transmission of the beacon information is stopped, request information for requesting the external apparatus to transmit beacon information specifying the communication reserved band reserved by the communication apparatus is transmitted to the wireless communication unit.

The communication device control method according to the present invention comprises the following arrangement. That is,
A communication device control method comprising:
A transmission step of transmitting beacon information including information specifying a communication reserved bandwidth;
When stopping transmission of the beacon information, a request step for requesting an external device to transmit beacon information that designates a communication reserved band reserved by the communication device by the beacon information;
Have

  According to the present invention, in a communication apparatus that performs communication by reserving a communication reserved band, when the communication apparatus shifts to a state in which transmission of beacon information specifying the communication reserved band is stopped, such as when the communication apparatus shifts to a power saving mode. Thus, it is possible to provide a technique that makes it possible to use the channel in a short time when returning to the normal operation mode.

  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.

<< Embodiment 1 >>
The configuration according to this embodiment will be described according to the WUSB standard. The configuration of the communication apparatus and the communication system according to this embodiment will be described with reference to FIGS. 1 and 2. The communication device may be realized by a single communication device, or may be realized by adding a plurality of functions as required.

(System configuration)
FIG. 1 is a block diagram illustrating a configuration of a communication apparatus according to the present embodiment. In FIG. 1, reference numeral 110 denotes a central processing unit (CPU) that performs processing for controlling the entire communication apparatus. A random access memory (RAM) 120 temporarily stores programs and data supplied from an external device. A read only memory (ROM) 130 stores programs and parameters that do not need to be changed. Reference numeral 140 denotes a wireless communication interface that realizes a wireless communication function. An antenna 150 is used for the wireless communication interface 140. The wireless communication device 100 may be realized by the above configuration, or may be realized by adding functions such as a storage device and a display device as necessary.

  In addition, it can also be comprised as an alternative of a hardware apparatus with the software which implement | achieves a function equivalent to the above each apparatus.

  In the present embodiment, an example in which the program and related data according to the present embodiment are loaded from the ROM 130 into the RAM 120 and executed is shown, but the present invention is not limited to this. For example, every time the program according to the present embodiment is operated, the program may be loaded into the RAM 120 from a hard disk device or a memory device in which the program is already installed. Alternatively, the program according to the present embodiment may be recorded in the ROM 130, configured so as to form a part of the memory map, and directly executed by the CPU 110.

  In this embodiment, for convenience of explanation, a configuration in which the communication apparatus according to this embodiment is realized by one apparatus will be described. However, a configuration in which resources are distributed to a plurality of apparatuses may be realized. For example, storage and calculation resources may be distributed in a plurality of devices. Alternatively, resources may be distributed for each component virtually realized on the communication device, and parallel processing may be performed.

  FIG. 2 is a diagram showing a configuration of a communication system in the present embodiment. In FIG. 2, reference numeral 210 denotes a WUSB host having a function as a host in the WUSB cluster 200. Reference numeral 220 denotes a WUSB device having a function as a device. In FIG. 2, there is only one WUSB device controlled by the WUSB host, but there may be a plurality of WUSB devices as necessary. In the communication system of this embodiment illustrated in FIG. 2, there are two WUSB clusters composed of a WUSB host and a WUSB device. In FIG. 2, another WUSB host 211 forms the WUSB cluster 201, and the WUSB device 220 is located in the communicable range of the WUSB clusters 200 and 201. Although the WUSB device 220 in this figure is a DBD, it may be a WUSB cluster in which DBD and SBD are mixed. Further, an SBD may exist instead of the WUSB host 211 in the communication range of the DBD 220.

(MAC layer frame structure)
Next, the frame configuration of the Media Access Control (MAC) layer used by the WUSB standard will be described with reference to FIG. FIG. 3 is a diagram schematically showing the format of a super frame of the WUSB standard.

  In the WUSB standard, communication time is managed in frame units called a super frame 300. The super frame is composed of 256 MASs 350 in units of 256 μs, and one super frame length is 65536 μs. The top 16 MAS of the super frame is assigned as BP 400, and the WUSB host and SBD transmit a beacon in BP 400 to reserve the band in the super frame as DRP. For example, the beacon 410 includes a beacon group parameter 411, a DRP IE (412), and other information elements (IE) 413, and notifies the arrangement of the MAS reserved by the DRP IE 412. When the WUSB host has a DBD in the WUSB cluster, superframe synchronization management with surrounding devices is performed by analyzing and transmitting packets that can be intercepted around the DBD via the DBD.

(Relationship between WUSB channel and MAC layer)
Next, the relationship between the WUSB channel of the WUSB standard and the MAC layer will be described with reference to FIG. FIG. 4 is a schematic diagram showing mapping from the WUSB channel to the MAC layer channel reservation.

  In FIG. 4, each DRP (420, 430, 440, 450, 460, 470) corresponds to a communication reservation time within a certain WUSB cluster. In these DRPs, a micro-scheduled management command (MMC) for controlling the data input / output direction is broadcast by the WUSB host. Here, the MMC is composed of a header and a plurality of IEs. A section from the MMC to the previous MMC is called a Transaction Group (TG). For example, the TG for the MMC 443 is 444.

(Superframe synchronization adjustment)
Next, a process in which WUSB hosts perform superframe synchronization adjustment via DBD will be described with reference to FIG. FIG. 5 is a sequence chart showing a processing flow when the WUSB host 210 performs synchronization adjustment of the superframe with the WUSB host 211 via the DBD 220. Here, the WUSB host 210 enables the count packet function in order to know the packets that the DBD 220 can intercept.

  First, in S110, the WUSB host 210 sends a SetWUSBData (Receive Params) request and makes a count packet initialization request to the DBD 220. The SetWUSBData (Receive Params) request includes setting of reception parameters including a reception packet filter, a reception channel, a reception start time, and a reception end time.

  When receiving the count packet initialization request, in S120, the DBD 220 initializes the count packet function.

  Next, in S130, the WUSB host 210 issues a count packet validation request to the DBD 220 with a SetFeature (COUNT_PACKETS) request. The SetFeature (COUNT_PACKETS) request includes setting of parameters such as the number of received packets, a period, and MAC header information. Upon receiving the count packet validation request, the DBD 220 validates the count packet in S140, and receives and stores the packet transmitted by the WUSB host 211 as in S101.

  In step S150, the WUSB host 210 transmits a GetStatus (Received Data) request in order to know the packet received by the DBD 220. When receiving the GetStatus (Received Data) request, the DBD 220 transmits the received packet to the WUSB host 210 in S160.

  In S170, the WUSB host 210 analyzes when a desired packet can be received. In FIG. 5, the packet desired by the WUSB host 210 is a beacon because it is used to adjust superframe synchronization between WUSB clusters. If the reception timing of the desired beacon is found by the received packet analysis in S170, the WUSB host 210 then activates the capture packet function and performs processing for analyzing the desired packet.

  In S180, the WUSB host 210 transmits a ClearFeature (COUNT_PACKETS) request to the DBD 220 in order to invalidate the count packet function. In response to receiving the ClearFeature (COUNT_PACKETS) request, the DBD 220 invalidates the count packet function in S190.

  In S200, the WUSB host 210 transmits a SetWUSBData (Receive Params) request to the DBD 220 to request initialization of the capture packet function. The SetWUSBData (Receive Params) request includes setting of reception parameters including a reception packet filter, a reception channel, a reception start time, and a reception end time. In response to receiving the SetWUSBData (Receive Params) request, the DBD 220 initializes the capture packet function in S210.

  In S220, the WUSB host 210 sends a capture packet function validation request to the DBD 220 with a SetFeature (CAPTURE_PACKET) request. When receiving the SetFeature (CAPTURE_PACKET) request, the DBD 220 enables the packet capture function in S230.

  Here, it is assumed that the DBD 220 receives and stores the beacon transmitted by the WUSB host 211 in S240.

  In S250, in order to analyze the content of the beacon received by the DBD 220, the WUSB host 210 transmits a GetStatus (Received Data) request. When receiving the GetStatus (Received Data) request, the DBD 220 transmits the received packet to the WUSB host 210 in S260.

  In S270, the WUSB host 210 can know a beacon slot that can be transmitted during BP by analyzing the beacon received by the DBD 220.

  In S280, the WUSB host 210 transmits a ClearFeature (CAPTURE_PACKET) request to the DBD 220 in order to invalidate the capture packet function. When receiving the ClearFeature (CAPTURE_PACKET) request, the DBD 220 invalidates the capture packet function in S290.

  In S300, the WUSB host 210 transmits a SetWUSBData (Transmit Params) request to the DBD 220 to request initialization of the transmit packet function. The SetWUSBData (Transmit Params) request includes transmission parameter settings including transmission time and a transmission time adjustment value. When receiving the SetWUSBData (Transmit Params) request, the DBD 220 initializes the transmit packet function in S310.

  In S320, the WUSB host 210 transmits a SetWUSBData (Transmit Data) request for setting transmission data including a MAC header and a payload to the DBD 220. When receiving the SetWUSBData (Transmit Data) request, the DBD 220 controls to store the received data.

  In S330, the WUSB host 210 sends a SetFeature (DEV_XMIT_PACKET) request to the DBD 220 to request transmission start of the saved transmission data. In S340, the DBD 220 transmits the beacon data received and stored in S320, and the WUSB host 211 can intercept the beacon. In step S350, the WUSB host 211 refers to the beacon intercepted in step S340 and performs superframe synchronization adjustment.

  In S360, the WUSB host 210 transmits a ClearFeature (DEV_XMIT_PACKET) request to the DBD 220 in order to invalidate the transmit packet function as necessary. When the ClearFeature (DEV_XMIT_PACKET) request is received, the DBD 220 invalidates the transmit packet function in S370.

(Normal operation during sleep)
Next, an operation in a normal configuration when the WUSB host sleeps will be described with reference to FIG. FIG. 6 is a timing chart showing a normal operation when the WUSB host 210 sleeps in the WUSB cluster 200 and the WUSB cluster 201 that have established synchronization between superframes. In FIG. 6, the horizontal axis represents the time axis.

  In the super frame N (300), the WUSB host 210 makes a transmit packet request to the DBD 220 in S330 and requests transmission of a beacon. In this superframe, the reserved bandwidths of the DRP 500 used by the WUSB host 210 and the DBD 200 and the DRP 510 used by the WUSB host 211 do not overlap.

  When the WUSB host 210 decides to sleep in the superframe N + 1 (301), a transmit packet stop request is transmitted in S360 within the superframe. Even in this frame, DRP 520 and DRP 530 do not overlap.

  In the superframe N + 2 (302), the WUSB host 210 and the DBD 220 do not transmit a beacon, but the WUB 211 generates the DRP 550 using the information of the previous superframe N + 1 (301).

  In the superframe N + 3 (303), the DRP 570 generated by the WUSB host 211 attempts to reserve as many MASs as possible. In subsequent superframes, when the WUSB host 210 recovers the WUSB channel, if the previously used DRP (for example, 520) is used, there is a possibility of colliding with the DRP used by the WUSB host 211. Therefore, in such a conventional configuration, the WUSB host 210 has to redo the DRP reservation from the beginning using the sequence chart procedure shown in FIG. 5, and there is a problem that it takes time to recover the WUSB channel. there were.

(Operation during sleep according to this embodiment)
Next, an operation during sleep in the configuration according to the present embodiment will be described with reference to FIG. FIG. 7 is a timing chart showing an operation during sleep in the configuration according to the present embodiment. As in FIG. 6, the horizontal axis represents the time axis.

  In superframe N (300), WUSB host 210 has DRP 500 for communicating with DBD 220, and the reserved bandwidth does not overlap with DRP 510 for communicating with WUSB host 211. In this frame, the DBD 220 does not transmit a beacon by the transmit packet function, but it may be.

  In FIG. 7, the WUSB host 210 is going to sleep in the super frame N + 1 (301). At this time, if the DBD 220 does not transmit a beacon using the transmit packet function, a beacon transmission request is sent to the DBD 220 using a transmit packet request (S300, S320, S330). The reserved bandwidths of DRP 520 and DRP 530 do not overlap even during this superframe. If the DBD 220 transmits a beacon using the transmit packet function before this superframe, the transmit packet request process can be omitted.

  In the super frame N + 2 (302), the WUSB host 210 stops beacon transmission, but the DBD 220 transmits a beacon in the period of the BP 402 by the transmit packet function. The DRP 540 is reserved by the beacon of the DBD 220, and the reserved bandwidth with the DRP 550 does not overlap. After this superframe, even if the host wakes up at an arbitrary time, since the DRP has already been reserved, the WUSB channel can be quickly restored.

(Operation of WUSB host)
Next, the operation of the WUSB host 210 will be described with reference to FIG. FIG. 8 is a flowchart showing an operation flow of the WUSB host 210.

  In step S500, the WUSB host 210 determines whether it sleeps. If not sleeping (NO in step S500), the process proceeds to step S510, the WUSB host 210 transmits a beacon, and the process returns to step S500 again.

  When the sleep is performed in step S500 (YES in step S500), in step S520, the WUSB host 210 refers to the command history stored in its own memory and determines whether the DBD 220 is instructed to transmit a beacon. If beacon transmission is instructed (YES in step S500), the process returns to step S500 again. If the WUSB host 210 has not instructed the DBD 220 to transmit a beacon (NO in step S500), the process proceeds to step S530.

  In step S530, the WUSB host 210 requests the DBD 220 for a series of beacon transmission requests. That is, it requests the DBD 220 to continue sending out a beacon for continuing to use the DRP (DRP 540, 560 in the example of FIG. 7) of the WUSB cluster 200 used so far. Thereafter, the process returns to step S500 again.

  FIG. 8 shows an example of the operation of the WUSB host, and it goes without saying that the same operation can be realized by other procedures.

(DBD operation)
Next, the operation of the DBD 220 will be described with reference to FIG. FIG. 9 is a flowchart showing an operation flow of the DBD 220.

  In step S600, the DBD 220 determines whether a packet transmission request has been received from the WUSB host 210. If not received (NO in step S600), the process returns to step S600. If received (YES in step S600), the process proceeds to step S610.

  In step S <b> 610, the DBD 220 determines whether a ClearFeature (DEV_XMIT_PACKET) request that is a request to invalidate a transmit packet is received from the WUSB host 210. If received (YES in step S610), the process returns to step S600 again. If not received (NO in step S610), the process proceeds to step S620.

  In step S620, it is determined whether DBD 220 has already transmitted a beacon. If it is transmitted (YES in step S620), the process returns to step S610 again. If not transmitted (NO in step S620), the process proceeds to step S630.

  In step S630, the DBD 220 transmits a beacon using the transmit packet function. With this beacon, the DRP (DRP 540, 560 in the example of FIG. 7) used for the communication of the WUSB cluster 200 is continuously secured. Then, it returns to step S610 again.

  FIG. 9 shows an example of the operation of the DBD, and it goes without saying that the same operation can be realized by other procedures.

  As described above, in the configuration according to the present embodiment, when the WUSB host shifts to the power saving mode in which the beacon is not transmitted, the WUSB host causes the WUSB device to transmit a beacon for securing DRP instead of the host. Request information is sent out. The WUSB device that has received the request information starts transmitting a beacon for securing the DRP that has been used so far based on the content. Thus, the beacon transmitted from the WUSB device maintains the communication reserved bandwidth even when the WUSB host is sleeping, and communication can be quickly returned when the WUSB host wakes up.

  In this embodiment, the description has been made assuming that WUSB is used as wireless communication. However, if communication is performed by reserving a reserved communication band, the method of this embodiment can be used to recover from sleep. Sometimes communication can start quickly.

<< Embodiment 2 >>
In the first embodiment, the case where there is one WUSB device with which the WUSB host communicates after returning from sleep has been described by way of example, but there may be two or more WUSB devices that communicate after returning from sleep. Good. In this embodiment, as an example, a case where there are two WUSB devices that communicate after returning from sleep will be described.

(System configuration)
The communication apparatus used in this embodiment is shown in FIG. The configuration of the communication system used in this embodiment is shown in FIG. FIG. 10 is a diagram showing a configuration of a communication system in the present embodiment.

  In FIG. 10, reference numeral 210 denotes a WUSB host having a function as a host in the WUSB cluster 200. Reference numerals 220 and 221 denote WUSB devices having functions as devices. In FIG. 10, only two WUSB devices are controlled by the WUSB host, but a plurality of WUSB devices may exist as necessary.

  In the communication system illustrated in FIG. 10, there are three WUSB clusters including a WUSB host and a WUSB device. In FIG. 10, another WUSB host 211 forms the WUSB cluster 201, and the WUSB device 220 is located in the communicable range of the WUSB clusters 200 and 201. Further, another WUSB host 212 forms the WUSB cluster 202, and the WUSB device 221 is located in the communicable range of the WUSB clusters 200 and 202. Note that the communicable ranges of the WUSB clusters 201 and 202 do not overlap.

  Although the WUSB devices 220 and 221 in FIG. 10 are DBDs, they may be WUSB clusters in which DBD and SBD are mixed. Further, instead of the WUSB host 211 in the communication range of the DBD 220 and the WUSB host 212 in the communication range of the DBD 221, a configuration in which an SBD exists may be used. The procedure in which the WUSB host 210 uses the transmit packet function for the WUSB cluster 202 via the DBD 221 can be realized using a procedure similar to that in FIG. The operation flow of the WUSB host 210, DBD 220, and DBD 221 in the present embodiment is the same as the flow shown in FIGS.

(Operation during sleep according to this embodiment)
Next, an operation during sleep in the configuration according to the present embodiment will be described with reference to FIG. FIG. 11 is a timing chart showing an operation during sleep in the configuration according to the present embodiment. In FIG. 11, the horizontal axis represents the time axis.

  In the super frame N (300), the WUSB host 210 has a DRP 500 for communicating with the DBD 220 and the DBD 221. The DRP 500 has a reserved bandwidth that does not overlap with the DRP 510 for communicating with the WUSB host 211 and the DRP 511 for communicating with the WUSB host 212. In the example of FIG. 10, the DRP 510 and the DRP 511 do not overlap with each other, so the reserved bands can overlap, but the DRP reserved bands do not have to overlap. In this frame, DBD 220 or DBD 221 does not transmit a beacon by the transmit packet function, but it may be.

  Consider a situation in which the WUSB host 210 tries to sleep in the superframe N + 1 (301). In this case, when the DBD 220 and the DBD 221 are not transmitting a beacon using the transmit packet function, the WUSB host 210 makes a beacon transmission request to the DBD 220 and the DBD 221 respectively. However, the beacon transmission request is made using a DBD transmit packet request (S300, S320, S330). The reserved bands of DRP 520 and DRP 530 / DRP 531 do not overlap even during this superframe. If DBD 220 or DBD 221 transmits a beacon using the transmit packet function before this superframe, the transmit packet request process can be omitted.

  In the superframe N + 2 (302), the WUSB host 210 stops beacon transmission, but the DBD 220 and DBD 221 transmit beacons during the BP 402 period by the transmit packet function. DRP 540 is reserved by the beacons of DBD 220 and DBD 221, and the reserved bandwidths with DRP 550 / DRP 551 do not overlap. Therefore, even if the host awakes at any time after this superframe, the DRP is already reserved and the WUSB channel can be quickly restored.

  As described above, in the configuration according to the present embodiment, when shifting to the power saving mode, the WUSB host transmits request information for transmitting a beacon for securing DRP to each of the WUSB devices. . Each of the WUSB devices that have received the request information starts sending a beacon for securing the DRP that has been used so far based on the contents. Thus, the communication reserved bandwidth is retained by the beacon transmitted from the WUSB device even when the WUSB host is sleeping, and each communication can be quickly restored when the WUSB host awakes.

<< 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, or 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 block diagram which shows the structure of a communication apparatus. 1 is a diagram illustrating a configuration of a communication system according to a first embodiment. It is the figure which showed typically the format of the super frame of a WUSB standard. It is the schematic diagram which showed the mapping from a WUSB channel to MAC layer channel reservation. It is a sequence chart which shows the flow of a process at the time of performing the synchronization adjustment of a super frame. It is a timing chart which shows normal operation | movement when a WUSB host sleeps. 3 is a timing chart illustrating an operation during sleep in the configuration according to the first embodiment. It is a flowchart which shows the flow of operation | movement of a WUSB host. It is a flowchart which shows the flow of operation | movement of DBD. It is a figure which shows the structure of the communication system in Embodiment 2. FIG. 6 is a timing chart showing an operation during sleep in the configuration according to the second embodiment.

Claims (10)

A communication device for performing wireless communication,
Wireless communication means for performing wireless communication with an external device;
Control means for causing the wireless communication means to transmit beacon information including information designating a communication reserved band;
With
The control means includes
When the transmission of the beacon information is stopped, the wireless communication unit transmits request information for requesting the external device to transmit beacon information specifying the communication reserved band reserved by the communication device. A communication device. The external device further comprises determination means for determining whether or not the beacon information specifying the communication band is transmitted,
The control means includes
2. The communication apparatus according to claim 1, wherein if the determination unit determines that the external apparatus is transmitting the beacon information, the request information is not transmitted to the wireless communication unit. The control means includes
The request for requesting the external device to transmit beacon information for designating the communication reserved band is transmitted to the wireless communication means when shifting to a power saving mode. Communication equipment. The communication device is a wireless USB host device,
The communication apparatus according to claim 1, wherein the external apparatus is a wireless USB device apparatus. A communication device control method comprising:
A transmission step of transmitting beacon information including information specifying a communication reserved bandwidth;
When stopping transmission of the beacon information, a request step for requesting an external device to transmit beacon information that designates a communication reserved band reserved by the communication device by the beacon information;
A method for controlling a communication apparatus, comprising: A determination step of determining whether or not the external device is sending out beacon information specifying the communication band;
The communication apparatus control method according to claim 5, wherein the external apparatus is requested to transmit beacon information specifying the communication reserved band according to a determination result in the determination step. 7. The communication device control method according to claim 5, wherein the requesting step requests the external device to transmit beacon information for designating the communication reserved band when shifting to a power saving mode. . The communication device is a wireless USB host device,
8. The communication apparatus control method according to claim 5, wherein the external apparatus is a wireless USB device apparatus.   The program for functioning a computer as a communication apparatus in any one of Claims 1 thru | or 4.   A computer-readable storage medium storing the program according to claim 9.

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