JP2011015373A - Wireless communication system, and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication system in which no trouble occurs in communication of DBD.SOLUTION: A wireless communication system includes a first host device, which constitutes a first wireless network and performs beacon transmission, and a beacon device connected with the first host device for performing beacon capturing or beacon transmission based on an instruction from the first host device. The first host device includes: a means for determining a communication status in a timeslot allocated to communication with the beacon device; a means for instructing beacon capturing to the beacon device in accordance with the determined communication status; a means for comparing a transmission source of a beacon sent from the beacon device with a transmission source of a beacon received by the first host device itself in accordance with the instruction; and a means for transmitting a beacon transmission instruction to the beacon device if a beacon transmission source which is not included in the transmission sources of the beacons received by itself exists in the sent beacon transmission source. The beacon device transmits a beacon in response to the transmission instruction, thereby establishing synchronism with the non-included beacon transmission source.

Description

  The present invention relates to a wireless USB wireless network system and a control method thereof.

  Wireless USB (hereinafter referred to as “WUSB”) technology has been developed as a short-range high-speed wireless transmission technology. The WUSB host has a function of operating according to a MAC protocol defined by the WiMedia standard. Terminals that operate according to the MAC protocol defined in the WiMedia standard synchronize between a plurality of networks by sending and receiving beacons to each other, and reserve communication time slots. On the other hand, WUSB devices can be classified into three types. The first is a non-beaconing device (hereinafter referred to as “NBD”), which omits a function that operates in accordance with the WiMedia protocol in order to simplify the implementation, and does not perform transmission / reception of beacons. The second is a Self Beaconing Device (hereinafter referred to as “SBD”), which operates according to the MAC protocol defined in the WiMedia standard and autonomously transmits and receives beacons. The third is a Directed Beaconing Device (DBD), which itself does not have a function that operates according to the MAC protocol defined in the WiMedia standard, but can operate as if it were a WiMedia terminal under the control of a WUSB host. . That is, the DBD does not autonomously send and receive beacons, but can send and receive beacons according to instructions from the WUSB host.

  In the MAC protocol defined in the WiMedia standard, media access timing is defined based on a repeatedly generated fixed-length superframe. A plurality of time slots (beacon slots) positioned at the start of the superframe are secured as areas (beacon periods) for each terminal to transmit a beacon. Each of the WUSB hosts controls beacon transmission according to a predetermined procedure so as not to transmit beacons in the same beacon slot as other WUSB hosts. Each WUSB host transmits a beacon including its own identification information, the beacon slot number used by itself, and the beacon slot number of the beacon received from other peripheral WUSB hosts. Each WUSB host selects a beacon slot to be used based on a beacon received from another WSB host, thereby enabling operation without causing a collision between the beacon slots of each other.

  Here, a state in which a plurality of WUSB hosts transmit beacons in the same beacon period is said to be synchronized with a plurality of WUSB hosts (synchronization of a plurality of networks). When asynchronous WUSB hosts recognize each other, they can synchronize by starting transmission of beacons in either beacon period according to a predetermined procedure. Even in a positional relationship where a plurality of WUSB hosts cannot receive beacons from each other, synchronization may be possible if a DBD exists between the WUSB hosts. For example, when a WUSB host transmits a beacon capture instruction to the DBD, the DBD receives a beacon transmitted by another WUSB host, and returns the received beacon content, reception timing, reception quality, etc. to the WUSB host as a response. To do. Based on the response from the DBD, the WUSB host can recognize a beacon from another WUSB host that cannot be received by itself and can synchronize with the other WUSB host. When the WUSB host transmits a beacon transmission instruction to the DBD, the DBD transmits a beacon having a specified content at a specified timing. Then, another WUSB host that has received the beacon transmitted from the DBD can synchronize between the WUSB hosts by controlling its own beacon transmission timing based on the analysis result of the received beacon. Become.

  Patent Document 1 introduces an example of synchronization between terminals operating in IEEE802.15.3.

  In Patent Document 2, the control station transmits a beacon interception request signal to the terminal station, and based on the information returned from the terminal station, the band is arranged so as not to overlap with the communication band of other control stations. Technology is disclosed.

Japanese Patent Laid-Open No. 2004-040645 JP 2008-306549 A

  In the case of a concurrent DBD that can communicate with multiple WUSB hosts, the host does not know whether the DBD is communicating with other hosts. At this time, if synchronization between the DBD and the host in communication is not established, a time slot reserved by a beacon may collide, which may hinder communication with the DBD. In view of such a problem, an object of the present invention is to provide a communication system that does not hinder DBD communication.

In order to solve the above-described problems, the present invention is configured to configure a first wireless network and perform beacon transmission, and be connected to the first host device. A beacon device that performs beacon capture or beacon transmission based on the first host device,
Means for determining a communication status in a time slot allocated to communication with the beacon device; means for instructing beacon capture to the beacon device according to the determined communication status; from the beacon device according to the instruction Means for comparing the source of the transmitted beacon with the source of the beacon received by itself, and the source of the beacon not included in the source of the beacon received by itself Means for transmitting a beacon transmission instruction to the beacon device, and the beacon device transmits a beacon in response to the transmission instruction, thereby establishing synchronization with the transmission source of the non-included beacon. It is characterized by being.

  According to the present invention, it is possible to adaptively synchronize a plurality of hosts, and to reduce the probability that a signal collision occurs between the host and the beacon device.

1 is a diagram illustrating a configuration of a wireless communication system according to a first embodiment. The figure which shows the outline | summary of the frame structure of WUSB. The figure which shows the example of the asynchronous state between DRP of the host 1 and DRP of the host 2. FIG. The figure which shows the example which detects asynchronous by the time difference between MMC of the host 1 and MMC of the host 2. FIG. FIG. 3 is a diagram showing an operation flow of the first embodiment. The figure which shows the operation | movement flow of Embodiment 2. The figure which shows the operation | movement flow of Embodiment 3. The figure which shows the operation | movement flow of Embodiment 4.

<Embodiment 1>
FIG. 1 shows a configuration of a wireless communication system according to the first embodiment. A WUSB host 101, which is a first host (control station), a device 103, and a DBD 102 (subordinate station) exist in the communication range 106 of the first wireless network. A WUSB host 104 as a second host, a device 105, and a DBD 102 exist in the communication range 107 of the second wireless network. The DBD 102 belongs to both the first network and the second network. Note that the devices 103 and 105 are NBDs. Arrows in the figure indicate communication relationships and directions. In this example, it is assumed that the communication method is a wireless USB method.

  FIG. 2 shows an outline of a super frame configuration in WUSB. FIG. 3 shows an example in which the WUSB host 101 and the WUSB host 104 are asynchronous and the DRP collides.

  A WUSB frame configuration will be described with reference to FIG. WUSB has a beacon period at the top of the superframe. The beacon period is divided into a plurality of beacon slots, and each device that transmits a beacon transmits a beacon in any one of the beacon slots. The beacon includes identification information of a beacon transmitting device received by each device and occupation information of each beacon slot. The part other than the beacon period includes a period of a plurality of distributed reservation protocols (hereinafter abbreviated as “DRP”) reserved for communication by each WUSB host. Each DRP period is composed of a plurality of time slots called transactions. The first transaction is called Micro-scheduled Management Command (hereinafter referred to as “MMC”), and the WUSB host uses the MMC packet (control packet) to specify the WUSB device that communicates in each transaction and the next MMC start time. Is notified to each WUSB device.

  A system configuration will be described with reference to FIG. 1 as an example of the present embodiment. The WUSB host 101 is in communication with the device 103 and the DBD 102 which is a beacon device. The WUSB host 104 is in communication with the device 105. The WUSB host 101 designates a device that communicates with the MMC for each transaction group in its own DRP. Referring to FIG. 2 as an example, the WUSB host 101 designates communication with the device 103 in the transaction T13 and designates communication with the DBD 102 in the transaction T14 in the MMC1. Similarly, in the MMC2, the communication of the DBD 102 is designated by the transaction T24, but the communication with the device 103 is not designated here.

  When adjacent networks are synchronized, there is no problem because DRPs do not overlap. However, DRP duplication may occur if they are not synchronized. Such a case will be described with reference to FIG. Since the WUSB host 101 and the WUSB host 104 cannot receive each other's signals, they become asynchronous and DRP overlap occurs.

  When the DRP overlaps, each part of the DRP as shown by the broken line in FIG. 3 is shown in the DBD 102 that communicates with the WUSB host 101 that is the first host and can receive the signal of the WUSB host 104 that is the second host. A shift occurs. Therefore, the DBD 102 may fail to receive the MMC because the MMC transmitted by the WUSB host 101 overlaps with the transmission signal of the WUSB host 104 or the transmission signal of the device 105 communicating with the WUSB host 104. . If the DBD 102 fails to receive the MMC, even if the MMC is instructed to perform communication in a predetermined transaction, the DBD 102 cannot know the instruction and cannot perform any communication in the transaction. This may be due to an unknown WUSB host adjacent to the DBD 102.

  The operation flow in the first embodiment will be described with reference to FIG. In S501, the WUSB host 101 is in communication with the device 103 and the DBD 102. In step S502, the WUSB host 101 checks whether communication with the DBD 102 is normally performed in the designated transaction. If communication is not normally performed in the designated transaction, the process proceeds to S503. This check is repeated when communication is performed normally. Note that the case where the communication is not normally performed means that the data from the DBD 102 is not sent, the ACK for the data transmitted to the DBD 102 is not returned, and the communication error rate is higher than a predetermined threshold value. This is the case when it falls. Further, the number of errors in a predetermined transaction in a plurality of transaction groups, an error rate, and the like may be measured, and it may be determined that communication is not normally performed when a predetermined threshold is exceeded. In step S503, the WUSB host 101 instructs the DBD 102 to perform beacon capture. When the DBD 102 cannot receive the MMC, it waits for reception of a signal transmitted from the WUSB host 101 until the next MMC can be received. Therefore, the DBD 102 can receive the beacon capture by instructing the beacon capture during the period when the DBD 102 will be waiting for reception.

  In step S504, when the beacon capture result is sent from the DBD 102, the WUSB host 101 compares the beacon transmission source received and recorded by the DBD 102 with the beacon transmission source received by the DBD 102. As a result of the comparison, if all the beacon transmission sources received by the DBD 102 are included in the beacon transmission sources received by the WUSB host 101, the process proceeds to S506. As a result of the comparison, when the beacon transmission source received by the DBD 102 is not included in the beacon transmission source received by the WUSB host 101, for example, when the WUSB host 104 is found, the process proceeds to S505.

  If the process proceeds to S506, it means that the transmission source of the beacon received by the DBD 102 is all synchronized with the WUSB host 101. Therefore, the fact that communication with the DBD 102 cannot be performed despite the synchronization is established, there is a possibility that the transmission output (transmission power) of the DBD 102 is small. Therefore, the WUSB host 101 instructs the DBD 102 to increase the transmission output.

  If the processing proceeds to S505, it means that there is a WUSB host that is not synchronized with the WUSB host 101 among the transmission sources of the beacons received by the DBD 102. Accordingly, the WUSB host 101 instructs the DBD 102 to transmit a beacon in order to synchronize with the WUSB host that is the beacon transmission source.

  In S507, communication is stabilized by causing the DBD 102 to increase the transmission output. Alternatively, by causing the DBD 102 to transmit a beacon, beacon synchronization processing starts between the WUSB host 101 and the WUSB host 104 based on the beacon, and synchronization is established between the WUSB host 101 and the WUSB host 104. .

  As described above, in the first embodiment, the USB host checks whether communication is normally performed with the DBD in a predetermined transaction. If not normally performed, the DBD is instructed to beacon capture, and the result of confirming the transmission source can be instructed to increase the output of the DBD or to transmit beacons, thereby synchronizing and stabilizing the communication.

<Embodiment 2>
In this embodiment, a procedure for synchronizing two hosts performed by the DBD 102 will be described. Here, it is assumed that the connection between the DBD 102 and the WUSB host 101 has already been established, and the DBD 102 discovers a new host in the adjacent network.

  When a new host is found, the DBD connects to that host and checks whether it is synchronized with the already connected host.

  In FIG. 4, NextMMC time information (next MMC packet transmission time information) included in a control packet (MMC packet) transmitted from each of the WUSB host 101 already connected and the newly connected WUSB host 104 is overlapped. It is a figure explaining the state which exists. FIG. 6 shows an operation flow related to the DBD 102 in the second embodiment.

  In step S601, it is assumed that the WUSB host 101 and the DBD 102 have already been connected and are communicating with each other. In step S602, the DBD 102 checks whether there is a registered host as a connection destination. In step S <b> 603, when the DBD 102 finds a registered WUSB host 104 as a connection destination, the DBD 102 performs connection processing to the WUSB host 104. Thereafter, communication with the WUSB host 104 is started, and communication is performed simultaneously with the WUSB host 101 and the WUSB host 104.

  In S604, the DBD 102 confirms the NextMMC time information and the transaction allocated to the DBD 102 based on the control packets received from the WUSB host 101 and the WUSB host 104, as shown in FIG. Then, the time until the next reception of the MMC packet or the time until the transaction assigned to the DBD 102 is calculated by an internal timer, and some of the communication times of the first wireless network and the second wireless network overlap. Judgment is made by detecting whether there is any.

  If the result of determination in step S <b> 605 is that there is an overlap, the DBD 102 transmits a beacon transmission instruction request to the WUSB host 101 or the WUSB host 104. The beacon transmission instruction request may be sent to either one of the hosts or both.

  In step S606, the DBD 102 receives a beacon transmission instruction transmitted by the WUSB host 101, the WUSB host 104, or both in response to reception of a beacon transmission instruction request, and transmits a beacon according to the instruction. As a result, synchronization is established between the WUSB host 101 and the WUSB host 104.

  As described above, in this embodiment, when the DBD 102 finds a new host, the DBD 102 connects to the host, and checks the communication time information included in the transmitted MMC packet, thereby synchronizing the DBD 102 with the connected host. Check if it is removed. If synchronization is not established, a beacon transmission instruction request is transmitted to the host, and a beacon is transmitted by receiving a transmission instruction from the host. Based on this beacon, two hosts can synchronize.

<Embodiment 3>
The third embodiment is a modification of the second embodiment. In Embodiment 2, upon discovering a new host, the DBD 102 immediately connected to the new host. However, in this embodiment, it is confirmed whether synchronization is established by comparing beacons sent from two hosts without immediately connecting to a new host.

  FIG. 7 shows an operation flow of the third embodiment. The configuration of the wireless communication system is the same as in FIG. The operation will be described below with reference to FIG.

  In S701, it is assumed that the WUSB host 101 and the DBD 102 have already been connected and are communicating.

  In step S <b> 702, the DBD 102 checks whether there is a connection registered host.

  If the connection registered WUSB host 104 is found in step S703, the beacon of the WUSB host 101 already communicating and the beacon of the newly found WUSB host 104 are received, and it is confirmed whether synchronization is established. If synchronization is established, the process proceeds to S707 to perform connection processing to the WUSB host 104.

  In S704, if synchronization is not established, a beacon transmission instruction request is transmitted to the WUSB host 101.

  In S705, the DBD 102 receives a beacon transmission instruction transmitted from the WUSB host 101 that has received the beacon transmission instruction request, and transmits a beacon according to the instruction. In step S <b> 706, the DBD 102 receives the beacon on the WUSB host 101 side and the beacon on the WUSB host 104 side in accordance with this beacon, and confirms whether synchronization has been achieved. If it is confirmed that the WUSB host 101 and the WUSB host 104 are synchronized, the process proceeds to S707, and the DBD 102 performs a connection process to the WUSB host 104.

  As described above, in this embodiment, when the DBD 102 discovers a new host, the DBD 102 checks whether the synchronization is established by checking the transmission timing of the beacon transmitted from each host. If synchronization is not established, a beacon transmission instruction request is transmitted to the host, and a beacon is transmitted by receiving the transmission instruction. The two hosts can synchronize based on this beacon. After synchronization is established, data communication can be performed while avoiding signal collision between the two wireless networks by connecting to a new host.

<Embodiment 4>
The fourth embodiment is a modification of the third embodiment. In the third embodiment, when a new host is found, the DBD 102 checks whether synchronization is established before connecting to the new host. In the present embodiment, when a new host is found, as in the second embodiment, a connection is made to the new host, and then the beacons sent from the two hosts are compared to confirm whether synchronization is established.

  FIG. 8 shows an operation flow of the fourth embodiment. The configuration of the wireless communication system is the same as in FIG. In step S801, it is assumed that the WUSB host 101 and the DBD 102 have already been connected and are communicating.

  In step S <b> 802, the DBD 102 checks whether there is a connection registered host. In step S <b> 803, when the DBD 102 finds a connection-registered WUSB host 104, the DBD 102 performs connection processing to the WUSB host 104.

  In step S804, the DBD 102 compares the beacon received from the WUSB host 101 and the beacon received from the WUSB host 104, and checks whether synchronization is established. If synchronization is established, the process proceeds to S807. If the synchronization is not established in S805, the DBD 102 transmits a beacon transmission instruction request to at least one of the WUSB host 101 and the WUSB host 104.

  In S806, the DBD 102 receives a beacon transmission instruction transmitted from the WUSB host 101 and / or the WUSB host 104 that has received the beacon transmission instruction request, and transmits a beacon according to the instruction. By using this beacon as a reference, synchronization between the WUSB host 101 and the WUSB host 104 is established.

  As described above, in this embodiment, when the DBD 102 discovers a new host, the DBD 102 connects to the host and checks the transmission timing of the beacon transmitted from each host, so that synchronization between a plurality of connected networks can be achieved. Check if it is removed. If synchronization is not established, a beacon transmission instruction request is transmitted to the host, and a beacon is transmitted by receiving the transmission instruction. The two hosts can synchronize based on this beacon.

Claims (12)

A first host device that configures a first wireless network and performs beacon transmission;
A beacon device connected to the first host device and performing beacon capture or beacon transmission based on an instruction from the first host device;
The first host device is
Means for determining a communication status in a time slot allocated for communication with the beacon device;
Means for instructing beacon capture to the beacon device according to the determined communication status;
Means for comparing the source of the beacon sent from the beacon device in response to the instruction with the source of the beacon received by itself;
Means for transmitting a beacon transmission instruction to the beacon device when there is a beacon transmission source that is not included in the transmission source of the beacon received by the beacon transmission source,
A wireless communication system, wherein synchronization with a transmission source of a beacon not included is established by the beacon device transmitting a beacon in response to the transmission instruction.   When there is no beacon transmission source that is not included in the beacon transmission source received by the beacon transmission source, the first host device instructs the beacon device to change the transmission power. The wireless communication system according to claim 1. A first host device that configures a first wireless network and performs beacon transmission;
A beacon device connected to the first host device and performing beacon transmission based on an instruction of the first host device;
The beacon device is
Means for discovering the second host device and performing connection processing to the second host device;
It is determined whether or not the first host device and the second host device are synchronized by comparing information included in control packets respectively transmitted from the first host device and the second host device. A determination means;
If the result of the determination is that they are not synchronized, means for transmitting a beacon transmission instruction request to the first host device and / or the second host device;
Means for receiving the beacon transmission instruction transmitted from the first host device and / or the second host device in response to the transmission instruction request by the beacon device;
A wireless communication system, wherein synchronization between the first host device and the second host device is established by transmitting a beacon in response to the beacon transmission instruction.   The determination unit of the beacon device includes a transmission time of a next control packet included in a control packet transmitted by the first host device and a transmission time of a next control packet included in a control packet transmitted by the second host device. The wireless communication system according to claim 3, wherein the wireless communication system determines that there is a wireless network that is asynchronous with the first host device in communication when the transmission time overlaps and is detected.   The wireless communication system according to claim 3, wherein the control packet is a wireless USB MMC (Micro-scheduled Management Command) packet. A first host device that configures a first wireless network and performs beacon transmission;
A beacon device connected to the first host device and performing beacon transmission based on an instruction of the first host device;
The beacon device is
When a second host device is found and the second host device is registered in advance as a connection destination, a beacon is received from the second host device and is synchronized with the beacon of the first host device. Determining means for determining whether or not
If the result of determination by the determination means is not synchronized, means for transmitting a beacon transmission instruction request to the first host device;
The beacon device receiving a beacon transmission instruction from the first host device in response to the beacon transmission instruction request;
A wireless communication system, wherein synchronization between the first host device and the second host device is established by transmitting a beacon in response to the beacon transmission instruction. A first host device that configures a first wireless network and performs beacon transmission;
A beacon device connected to the first host device and performing beacon transmission based on an instruction of the first host device;
The beacon device discovers a second host device, and when the second host device is registered in advance as a connection destination, means for performing a connection process to the second host device;
A determination unit that compares the beacon of the first host device and the beacon of the second host device and determines whether synchronization is established;
If the result of determination by the determination means is not synchronized, means for transmitting a beacon transmission instruction request to the first host device and / or the second host device;
Means for receiving a beacon transmission instruction transmitted from the first host device and / or the second host device in response to the beacon transmission instruction request;
A wireless communication system, wherein synchronization between the first host device and the second host device is established when the beacon device transmits a beacon in response to the beacon transmission instruction.   The wireless communication system according to any one of claims 1 to 7, wherein the communication system is a wireless USB system. A first host device that performs beacon transmission;
In a wireless communication system including a beacon device connected to the first host device and performing beacon transmission based on an instruction of the first host device,
The first host device is
A determination step of determining a communication status in a time slot allocated to communication with the beacon device;
According to the determined communication status, an instruction step for instructing beacon capture to the beacon device;
A comparison step, wherein the comparison means compares the transmission source of the beacon sent from the beacon device with the transmission source of the beacon received by itself;
A transmission step of transmitting a beacon transmission instruction request to the beacon device when a transmission unit includes a beacon transmission source that is not included in the transmission source of the beacon received by the transmission unit; Run
A control method of a wireless communication system, wherein synchronization with a transmission source of a beacon not included is established when the beacon device transmits a beacon in response to the beacon transmission instruction request. A first host device that performs beacon transmission;
In a wireless communication system including a beacon device connected to the first host device and performing beacon transmission based on an instruction of the first host device,
The beacon device is
Discovering a second host device and performing a connection process to the second host device;
It is determined whether or not the first host device and the second host device are synchronized by comparing information included in control packets respectively transmitted from the first host device and the second host device. A determination process;
As a result of the determination, if not synchronized, a step of transmitting a beacon transmission instruction request to the first host device and / or the second host device;
Performing a step of receiving a beacon transmission instruction transmitted from the first host device and / or the second host device in response to the beacon transmission instruction request;
A control method for a wireless communication system, wherein synchronization between the first host device and the second host device is established by the beacon device transmitting a beacon in response to the beacon transmission instruction. A first host device that performs beacon transmission;
In a wireless communication system including a beacon device connected to the first host device and performing beacon transmission based on an instruction of the first host device,
The beacon device is
When the determination unit finds the second host device and the second host device is registered in advance as a connection destination, the beacon is received from the second host device and compared with the beacon of the first host device. A determination step for determining whether or not synchronization is achieved,
If the transmission means is not synchronized as a result of the determination, a transmission step of transmitting a beacon transmission instruction request to the first host device;
A receiving means for receiving a beacon transmission instruction from the first host device in response to the beacon transmission instruction request;
A control method for a wireless communication system, wherein the beacon device transmits a beacon in response to the beacon transmission instruction to establish synchronization between the first host device and the second host device. A first host device that performs beacon transmission;
In a wireless communication system including a beacon device connected to the first host device and performing beacon transmission based on an instruction of the first host device,
A connection step in which the beacon device discovers the second host device, and when the second host device is registered in advance as a connection destination, a connection step of performing a connection process to the second host device;
A determination step of comparing the beacon of the first host device and the beacon of the second host device to determine whether or not synchronization is established;
A transmission step of transmitting a beacon transmission instruction request to the first host device and / or the second host device when the transmission means is not synchronized as a result of the determination;
A receiving means for receiving a beacon transmission instruction from the first host device and / or the second host device in response to the beacon transmission instruction request;
A control method for a wireless communication system, wherein the beacon device transmits a beacon in response to the beacon transmission instruction to establish synchronization between the first host device and the second host device.

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