JP2005167367A - Radio communication device and radio communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication device performing quick data transfer by switching master and slave, while maintaining connection. <P>SOLUTION: The radio communicating method comprises a step for establishing radio connection between first and second radio communications devices, a step for setting the first radio communications device as a master and setting the second radio communications device as a slave, steps (S210-S230) for switching the second radio communications device to the master and the first radio communications device to the master, while maintaing radio communication, when data are transmitted from the second radio communications device set as a slave to the first radio communications device set as a master, and a step (S240) for transmitting data from the second radio communications device switched to master to the first radio communications device switched to a slave. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a wireless communication device, and more particularly, to a wireless communication device employing a master / slave connection method.

  Bluetooth (registered trademark, the same applies hereinafter) is a short-range wireless communication standard, and realizes wireless communication within 10 m using a 2.4 GHz band ISM (Industry Science Medical) band.

In Bluetooth, one master and one or more slaves always configure a wireless network (piconet) and perform communication. Every terminal needs to be able to function in both roles of master and slave, and has a function of switching the roles of master and slave during connection. Here, the master is a terminal corresponding to a server in a client server of a computer network, and performs communication while controlling a wireless network in Bluetooth. On the other hand, the slave is a terminal corresponding to the client, and performs communication while being controlled by the master.

Thus, a wireless data link (or connection) can be established between a master and a slave, but cannot be established between a slave and a slave.

Consider data communication in a piconet composed of one master (terminal 1) and two slaves (terminals 2 and 3). The wireless data link consists of terminal 1 (master) and terminal 2
(Slave) and between terminal 1 (master) and terminal 3 (slave), but not between terminal 2 (slave) and terminal 3 (slave). For this reason, even when data is transferred between slaves (for example, from the terminal 2 to the terminal 3), the data must be passed through the master (terminal 1), resulting in a delay compared to the case of direct transfer. Such a delay may impair communication quality in the case of communication such as a moving image that requires real-time characteristics.

For this reason, in a conventional wireless communication system, a terminal that requires a large transmission capacity such as a moving image (
If the terminal 2) is a slave, the procedure for disconnecting the data link between the terminal 1 (master) and the terminal 3 (slave) (step 1), the procedure for switching the terminal 2 to the master, and the terminal 1 to the slave (step 2), A new piconet is formed by executing three steps of a procedure (step 3) for forming a data link between the terminal 2 (new master) and the terminal 3 (slave), and then from the terminal 2 to the terminal 3 Data transfer is performed (see, for example, Patent Document 1).
JP 2002-190806 A (7th and 8th pages, FIG. 1)

However, in the wireless communication system described above, before data transfer, the procedure for disconnecting the data link between the terminal 1 (master) and the terminal 3 (slave), and between the terminal 2 (new master) and the terminal 3 (slave) Thus, data transfer cannot be performed unless a procedure for forming a data link (connection) and a time-consuming procedure for disconnecting and forming a connection in the piconet are passed.

The object of the present invention is to switch between the master and the slave while maintaining the connection,
It is an object of the present invention to provide a wireless communication device that performs quick data transfer.

According to a first aspect of the present invention, there is provided a step of wirelessly connecting a first wireless communication device and a second wireless communication device, the first wireless communication device as a master, and the second wireless communication device as a slave. And when transmitting data from the second wireless communication device that is a slave to the first wireless communication device that is a master, the second wireless communication device is mastered while maintaining the wireless connection. A step of switching the first wireless communication device to a master, and a step of transmitting the data from the second wireless communication device that is a master to the first wireless communication device that is a slave after the switching. A wireless communication method.

A second invention is a wireless communication device for master-slave wireless connection with another wireless communication device, and means for confirming whether the device is a slave before transmitting data, and when the device is a slave A wireless communication apparatus comprising: means for requesting switching of the master / slave to the other wireless communication apparatus while maintaining the wireless connection; and means for transmitting the data after switching from the slave to the master.

According to a third aspect of the present invention, there is provided an electronic device that transmits data to a second wireless communication device that is master-slave wirelessly connected via the first wireless communication device, and before the data transmission, the first device A means for confirming whether the wireless communication device is a slave, and when the first wireless communication device is a slave, a request to switch the master slave is made to the first wireless communication device while maintaining the wireless connection. And a means for instructing the first wireless communication device to transmit the data after the first wireless communication device is switched from the slave to the master.

According to the present invention, the master and the slave are switched while maintaining the connection,
A wireless communication apparatus that performs quick data transfer can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a wireless communication system according to the present embodiment. Here, a case where the host device A and the host device B perform wireless communication will be described. Each host device is Blueto
The oth device A or B is connected to each other, and wireless communication by Bluetooth is performed between the Bluetooth devices.

The host device A manages an application layer 110 that executes a communication application such as data communication, and logical link management (L2CAP; Logical Link Control and Adaptation Protocol) that manages application data as a logical channel and performs data division and data reconfiguration.
ol) HCI (Host Control Interfa) that interfaces between layer 120 and Bluetooth device A
ce) layer 130. On the other hand, the Bluetooth device A has an HCI layer 210 that interfaces with the host device A, and link management (LM; Link Manager) that sets communication links (for example, master and slave) and various communication parameters related to the links. Layer 22
0, link control (LC) layer 230 for performing baseband processing such as transmission / reception frequency designation / switching for managing frequency hopping and time axis slot management, and Bluetooth device B for radio communication And a physical (RF) layer 240 to be performed.

The application layer 110 and the L2CAP layer 120 are CPU (Central Processing Unit).
) And software executed on the memory. The HCI layers 130 and 210 are constituted by hardware, the LM layer 220 and the LC layer are constituted by firmware incorporated in a signal processing chip, and the RF layer 240 is constituted by a high frequency circuit. Host device B
Since the Bluetooth device B has the same configuration, the description thereof is omitted.

Therefore, the following connections are made between the layers of the host devices A and B (or Bluetooth devices A and B). The user logical channel (user data) at the L2CAP layer (120 and 320), the communication link management channel (control packet) at the LM layer (220 and 420), the communication link (packet) at the LC layer (230 and 430), RF layer (240 and 44
In 0), a physical link (wireless) is connected.

In this connection (connection), the Bluetooth devices A and B are given a role of a master or a slave and perform wireless communication.

FIG. 2 is a flowchart of master-slave switching according to the present embodiment. Here, the application layer 110 of the host device A to the application layer 31 of the host device B
The operation when data is transmitted to 0 will be described. It is assumed that the Bluetooth devices A and B are already connected for communication. When receiving a data transmission request from the user (S210), the application layer 110 inquires of the L2CAP layer 120 whether the Bluetooth device A is connected as a master or a slave (S220).
). The L2CAP layer 120 makes an inquiry to the LM layer 220 of the Bluetooth device A via the HCI layer 130 and informs the application layer 110 whether it is connected as a master or a slave.

When connected as a slave, the application layer 110 makes a master-slave switching request to the L2CAP layer 120 while maintaining the connection (S230). The L2CAP layer 120 makes a master / slave switching request to the Bluetooth device A via the HCI layer 130. Bl
The LM layer 220 of the uetooth device A transmits a master / slave switching request packet to the LM layer 420 of the Bluetooth device B. After the Bluetooth device A becomes the master, the application layer 110 transmits data (S240). On the other hand, when connected as a master,
Sends data immediately without issuing a master / slave switching request.

As in the above-described embodiment, when the Bluetooth device on the data transmission side is a slave, FIG. 3 to FIG. 5 are used to determine whether data can be transferred quickly by switching to the master and transmitting while maintaining the connection. I will explain.

FIG. 3 is a baseband timing chart when data is transmitted from the master to the slave. The master can transmit a data packet at an arbitrary timing. Here, the packet format in Bluetooth is configured in the order of an access code, a packet header, and a payload. The access code indicates the destination of the transmission packet, and the access code is always added to all packets transmitted and received. The packet header has parameters for managing the communication link. The payload is a portion on which actual user data is placed.

On the other hand, the slave transmits a NULL packet for packet reception confirmation. This NU
The LL packet is a packet composed of an access code and a packet header, and has no payload. Then, it is not necessary to acknowledge the packet in response to receiving the NULL packet.

FIG. 4 is a baseband timing chart when data is transmitted from the slave to the master. As mentioned above, the master can send data to the slave at any time, but when sending data from the slave to the master, the slave receives some packet from the master and sends data only in the next slot. Can not do it.

In the next slot that has received data from the slave, the master confirms the receipt of A
Since a NULL packet is transmitted as CK, the slave can continuously transmit data. However, once data transmission is interrupted, it cannot be resumed. Therefore, the master performs polling using a POLL packet in order to receive data from the slave. A POLL packet is normally transmitted at an interval determined by a value called a POLL interval. In the present embodiment, a POLL packet is transmitted every 40 slots, and one slot has an interval of 625 μS. A POLL packet is a packet composed of an access code and a packet header, similarly to a NULL packet, and functionally manages the state of a communication link in the same manner as a NULL packet. However, a POLL packet is different from a NULL packet, and P
In response to receiving the OL packet, a packet reception confirmation response must be made even if there is no data to be transmitted.

As described above, since baseband communication is performed by a polling method by a master, data transmission from the master to the slave is generally faster than data transmission from the slave to the master.

Depending on the implementation of the LC layer firmware, as shown in FIG. 5, it is possible to easily transmit data from the slave by forcibly transmitting a NULL packet to the slave during the POLL interval. However, it depends only on the implementation by rewriting the firmware, and it is not guaranteed that all Bluetooth devices perform such an operation.

However, in this embodiment, the Bluetooth device is not tampered with, and the data transfer rate of Bluetooth communication can be increased by improving only the application layer of the host device as described in FIG.

The above-described embodiment is a preferred specific example of the present invention, and thus various technically preferable limitations are attached. However, the embodiments may be appropriately combined and changed within a range not departing from the gist of the present invention. Needless to say, you can. For example, the present invention can be applied even when the host device and the Bluetooth device are integrated.

1 is a schematic configuration diagram of a wireless communication system according to the present embodiment. The flowchart of the master-slave switching which concerns on this embodiment. Baseband timing chart when transmitting data from master to slave. A baseband timing chart when data is transmitted from a slave to a master. A baseband timing chart in a case where data transmission from the slave to the master is facilitated by forcibly transmitting a NULL packet to the slave during the POLL interval.

Explanation of symbols

100 Host device A
110, 310 Application layer 120, 320 L2CAP layer 130, 210, 330, 410 HCI layer 200 Bluetooth device B
220, 420 LM layer 230, 430 LC layer 240, 440 RF layer 300 Host device B
400 Bluetooth device B

Claims (3)

Wirelessly connecting between the first wireless communication device and the second wireless communication device;
Setting the first wireless communication device as a master and the second wireless communication device as a slave;
When transmitting data from the second wireless communication device that is a slave to the first wireless communication device that is a master, the first wireless communication device is used as a master while maintaining the wireless connection, and the first wireless communication device is the first wireless communication device. Switching the wireless communication device to master
And a step of transmitting the data from the second wireless communication device that is a master to the first wireless communication device that is a slave after switching. A wireless communication device for master-slave wireless connection with another wireless communication device,
Before sending data, means to check whether the device is a slave,
If the own device is a slave, means for making a master-slave switching request to the other wireless communication device while maintaining the wireless connection;
And a means for transmitting the data after switching from the slave to the master. An electronic device that transmits data to a second wireless communication device connected by a master-slave wireless connection via a first wireless communication device,
Means for confirming whether the first wireless communication device is a slave before the data transmission;
When the first wireless communication device is a slave, means for making a master-slave switching request to the first wireless communication device while maintaining the wireless connection;
A wireless communication apparatus comprising: means for instructing the first wireless communication device to transmit the data after the first wireless communication device is switched from a slave to a master.

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