KR20030087746A - Method and apparatus for communication between two piconets within bluetooth scatternet - Google Patents

Abstract

The present invention relates to a communication method using Bluetooth, and to provide a communication method capable of effectively transferring data between piconets composed of one master and a slave, and two communication methods have been proposed. The first method transfers data from a node of one piconet to a node of another piconet through an arbitration slave node, and the second method transfers data from a node of one piconet to another node through a mediation node. It is characterized by transferring data to the nodes of the piconet. In the case of the conventional Bluetooth technology, a procedure for communicating with each other in one piconet is established, and bidirectional communication is performed between nodes under the master's initiative, but a method for communicating between nodes belonging to different piconets is not defined separately. Did. The present invention proposes a method for communicating between nodes in different piconets through efficient routing according to the initiative of one node on a scatternet composed of two piconets.

Description

Method and apparatus for communication between two piconets within bluetooth scatternet}

The present invention relates to a communication method using Bluetooth, and more particularly, to a communication method for enabling smooth communication between nodes in different piconets.

In the unlicensed frequency band (typically 2.4 GHz), Bluetooth uses seven channels under the leadership of one master, which can schedule slots for transmitting packets using Frequency Hopping Spread Spectrum (FHSS). International standard technology for short-range wireless communication that can communicate with slaves up to. This configured network is the smallest network of Bluetooth, called a piconet, and one master must exist in one piconet. It is also possible to configure different piconets by assigning different frequencies. A network composed of multiple piconets is called a scatternet.

In the case of the conventional Bluetooth technology, a procedure for communicating with each other is established in one piconet, and bidirectional communication between two nodes can be performed in a time division duplex (TDD) scheme under the master's initiative.

However, a method for communicating between nodes belonging to different piconets was not defined separately. Due to the characteristics of wireless communication, the transmission distance was about 10m and using an amplifier was possible up to 100m.

An object of the present invention is to provide a procedure for enabling routing between master nodes through slave nodes shared with each other in order to enable communication between master nodes of different piconets in a Bluetooth scatternet. The present invention provides a procedure for enabling routing between the master node and the slave node through a master / slave role switching mechanism to enable communication between the master node and the slave node of the piconet.

1 is a block diagram of a basic piconet and a scatternet.

2 is a block diagram of a scatternet to which the present invention is applied.

3 is a flow diagram for transferring data from a node in one piconet to a node in another piconet via an arbitration slave node in accordance with the present invention.

4 is a flow chart for transferring data from a node of one piconet to a node of another piconet through an arbitration node that switches roles from master to slave according to the present invention.

5 is a communication apparatus between two piconets effectively controlling the role switching of an arbitration node according to the present invention.

The present invention for solving the above technical problem includes a method invention, a device invention, a recording medium invention.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention. First, in order to help the understanding of the above embodiment, a connection protocol between Bluetooth devices will be described.

The wireless channel, which is a communication medium of Bluetooth, is largely divided into a standby state and a connection state in order to provide a communication function, and frequency hopping, a kind of spectrum spreading method, to eliminate interference with other devices. It is adopted. In the frequency hopping scheme, a frequency is randomly switched for each slot to prevent interference by a fixed transmission frequency. Two-way communication is performed between Bluetooth devices in a manner called time division duplex (TDD) in which transmission and reception are alternately performed. In addition, one packet can span a plurality of slots.

The standby state is a basic state of a Bluetooth device, and in order to communicate with another device outside of the standby state, it is necessary to inquiry whether there is a device equipped with Bluetooth in an area to which its radio wave propagates. (View status). At this time, the Bluetooth-equipped devices in the vicinity of the querying device should periodically perform an inquiry scan (inquiry scan state), and the inquiry scan state is a state of scanning whether a connection frequency for inquiry is sent. The inquiry scan determines that there is an inquiry from another device, and the inquiry response is a packet according to the frequency hopping sequence (FHS) (query response state). The device making the inquiry can know the address of the counterpart device through the inquiry response. The device (originating device) that wants to establish a connection starts a page process using a specific address (page state). In this case, the called device should be periodically scanning the page (page scan state). The page scan state is a process of comparing the hop frequency with its own frequency for one hop frequency, and the page duration is generally paged. The connection can be established because it is longer than the scan period. When the device recognizes that the page is being scanned through the page scan, the device immediately establishes a connection, and in the normal case, the connection is successfully established. In general, if one device wants to connect with another device, the device requesting the connection setup sends a page message if it knows the other party's address. Otherwise, it sends an inquiry message after the page message. At this time, the device requesting the connection setup, that is, the paged device is set as the master, and the device which has responded to the page is set as the slave. The master and the slave are called roles, and the slave is synchronized with the internal clock of the master. However, the slave may require a change of role and basically has a function possessed by the master.

The connection state is a state in which a connection is established and a packet is exchanged, and both devices use a channel access code and a clock of a master, and a hopping order follows a channel hopping sequence. The connected state has three states, an active mode, a sniff mode, and a hold mode. In addition, there are a park mode. From the active mode, a transition can be made to the sniff mode, the hold mode, or the park mode by either request.

The active mode is a state in which a certain channel occupies between Bluetooth devices and a master sends and receives data by scheduling a transmission based on a traffic parameter requested by another slave, or a slave waits for data from a master. The sniff mode corresponds to a slave only mode, in which a time slot transmission interval contracted with the master is set to reduce a period in which the slave keeps an eye on the master's data. The hold mode is a state in which a slave temporarily does not support an acknowledgment packet for a channel and uses it to scan, page, and query all capabilities to join another piconet. The park mode is a mode in which the slave no longer needs to participate in the piconet channel and the slave enters a low power state where there is little activity if it wants to keep it synchronized.

1 is a block diagram of a basic piconet and a scatternet.

The network between Bluetooth-equipped devices does not have fixed control devices, and each mobile device organizes its own network. The Bluetooth system makes a one-to-one (11) or one-to-many (12) connection. A network in which two or more Bluetooth devices share the same channel is called a piconet. In one piconet, one device becomes the master and can be connected with up to seven active slaves. Therefore, the device that does not communicate is switched to the park mode. In total, up to 255 devices can be included in one piconet. For all slaves in active or park mode, access to the channel is controlled by the master. A state 13 in which several piconets overlap is called a scatternet. The piconets in the scatternet do not need to be synchronized with each other, and each piconet has its own channel according to its master.

The present invention provides a method through a slave belonging to the latter piconet and a method in which a slave belonging to the latter piconet switches a role from slave to master in order to communicate between the source piconet and other destination piconets to which data is to be transferred. It is characterized by providing. In addition, by defining a state variable to be used for the purpose of the role switching, and to include in the Bluetooth function implemented at the chip level, it provides a method for enabling high-speed routing between nodes in the scatternet. .

2 is a schematic diagram of a scatternet composed of two piconets to which the present invention is applied. One piconet is a piconet 201 in which a communication between a master and a slave is established and communication has already been established. A node 1 21 in the center of the nodes belonging to the piconet 201 is a master node, and a neighboring node 2 ( 22) is a slave node. The other piconet 202 has as a shared node a node 2 22 of the piconet 201 in which the communication is established, which is within communication reach with its own node 3 12 as a piconet that has not yet been established. It is a technical gist of the present invention to perform communication between nodes belonging to two piconets through node 2 (22) which is the shared node. In the case of wireless communication, communication is possible only within the communication reach distance 201 or 202 of the effective radio wave due to the limitation of the signal strength. However, the present invention includes two piconets if communication between nodes of different piconets is enabled by the present invention. The communication reach distances 201 and 202 are extended by space, and further, when data is sequentially transmitted between nodes of several piconets, the communication reach distance is extended by the space including the multiple piconets.

3 shows a procedure for the source node 3 33, which has not yet established communication, to communicate with the destination master node 1 31 of the piconet to which communication has been established via the arbitration slave node 2 32 of the piconet to which communication has already been established. It is a figure for demonstrating.

First, when a source node 3 (33) with no communication set up predominantly requests (301) a page to an arbitration slave node 2 (32) of the piconet in which the communication at a communication reach with the source node 3 is established, The originating node 3 33 becomes the master and the arbitration node 2 32 becomes the slave because the paged device is set as the master and the device that responds to the page is set as the slave. Thus, the arbitration node 2 32 acts as a slave to both the destination node 1 31 and the source node 3 33. The arbitration slave node 2 (33) requests (302) a transition to hold mode to the destination master node 1 (31), which is an existing master, for connection with the source node 3 (33) for which communication is not established. , 32 itself responds to the source master node 3 (33) that is the new master (303) indicating that it is a slave to the page. At this time, the source master node 3 (33) requesting communication includes the arbitration slave node 2 (32) to form a new piconet. The source master node 3 (33) transmits a packet 304 to the arbitration slave node 2 (32) to transmit data to the destination master node 1 (31), the arbitration slave node 2 (32) Transition to hold mode is requested 305 to the source master node 3 (33) to reconnect with the piconet. The arbitration slave node 2 32 requests 306 the release of the hold mode to send the packet to the destination master node 1 31, and according to the slot assignment of the destination master node 1 31. The packet is transmitted (307) to the destination master node 1 (31). Conversely, when the destination master node 1 31 transmits a packet or a response message to the source master node 3 33, the reverse operation is performed.

4 shows that destination master node 1 (41) of the piconet, which has already established communication, informs arbitration node 2 (42) of the established piconet that there is a communication request to origin node 3 (43), for which communication has not yet been established. 4 illustrates a procedure for communicating with a source node 43 for which communication is not established through the arbitration node 2 42 that switches a role from a master to a slave.

A communication request 401 to the destination master node 1 (41) of the piconet to which the communication is established, to a source node 3 (43) on which communication is not established at a communication reach distance with the arbitration slave node 2 (42) of the piconet to which the communication is established. Informing the arbitration slave node 2 42 that it is present, the arbitration slave node 2 42 requests 402 a transition to the hold mode to the destination node 1 41, and the arbitration slave node 2 42. Request a page 403 to source node 3 (43) for which communication has not been established. At this time, the source node 3 43, in which the communication is not established, responds 404 to the page indicating that it is a slave. The arbitration node 2 42 requesting the page becomes a master for the source node 3 43 (referring to the dual role of being a slave for the destination master node 1 by reference), and thus the source node 3 being a slave. The mediation node 2 42 swaps the master / slave role with the source slave node 3 43 so that 43 can dominate communication with the destination master node 1 41 (405). The method for switching roles is specified in FIG. 4. The role switch of FIG. 4 is achieved by exchanging states in the data structure via data packets (410, 411, 412, 413). After the role switching, the source slave node 3 43 becomes a master and transmits a packet containing data to be transmitted to the destination master node 1 41 to the arbitration node 2 42 (406). Arbitration node 2 (42) requests (407) the hold mode to the source master node 3 (43) to connect with the destination master node 1 (41), and then requests a connection to the destination master node 1 (41). In step 408, the packet is transmitted (409).

FIG. 5 is a communication device between two piconets which is mounted on a Bluetooth device to realize communication between the two piconets and effectively controls the switching of roles of the nodes that mediate the two piconets.

Bluetooth's general protocol stack is the lowermost part of the RF (Radio Frequency), which defines the physical layer, the baseband, which defines the hopping pattern, etc., the link manager, which defines the configuration of packets, and the L2CAP (Logical Link and Control Adaptation). Protocol), and the upper part is composed of Human Interface (HID) and Serial Cable Emulation Protocol (RFCOMM) that define the interface between host systems.

The link manager 501 receives a packet connection request from an upper host and communicates with a transmission / reception control unit 502 as a module for controlling lower transmission / reception. The transmission and reception control unit stores a variable for controlling the master and the slave (that is, M / S 506 which is a variable indicating whether it is a master or a slave, and a slave index 507 which is a variable indicating which slave in a piconet). There is a control automata 503, which serves as the left piconet and the right piconet of the node sharing and mediating the two piconets, i.e. as slave / master (410 in FIG. 4) or slave / slave (412 in FIG. 4). To control the role, the role for one piconet consists of one nibble (1/2 byte) and consists of 1 byte as a whole. As described above, the transmission / reception control unit generates and stores the arbitration node control variable under the control of the link manager, and controls the transmission / reception unit and the transmission / reception memory according to the arbitration node control variable. The transceiver 504 looks at the arbitration node control variable stored in the control automata 503, and the slave number 508 stored in the transmission / reception memory 505 and the channel corresponding to the number as indicated by the arbitration node control variable. The state information 509 and the channel device information 510 are read and transmitted and received, and the data contained in the packet is transmitted to the upper layer through the transmit / receive memory. The channel state information indicates various states of devices sharing one channel, that is, standby, page, slave response, hold, hold release, and data packet transmission. The channel device information is a clock of the channel and a distinguishing mark between the devices. Represents an address.

511 and 512 of FIG. 5 are examples of 410 and 411 of FIG. 4, and the arbitration node 2 (42 in FIG. 4) serves as slave number 5 for the left piconet and master for the right piconet. (43 in FIG. 4) serves as slave number 3 for the left piconet, and indicates that it is not set for the right side. After the role switch, 513 and 514 of FIG. 5 are examples of 412 and 413 of FIG. 4, and the arbitration node 2 (42 of FIG. 4) serves as slave number 5 for the left piconet and slave number 3 for the right piconet. Source node 3 (43 in FIG. 4) serves as a master for the left piconet, and not set for the right.

Meanwhile, the above-described embodiments of the present invention can be written as a program that can be executed in a computer, and can be implemented in a general-purpose digital computer that operates the program using a computer-readable recording medium.

In addition, the structure of the data used in the above-described embodiment of the present invention can be recorded on the computer-readable recording medium through various means.

The computer-readable recording medium may be a magnetic storage medium (for example, a ROM, a floppy disk, a hard disk, etc.), an optical reading medium (for example, a CD-ROM, DVD, etc.) and a carrier wave (for example, the Internet). Storage medium).

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

According to the present invention, within a scatternet composed of piconets, communication between two piconets is made possible by routing from an originating node having no communication established to a destination master node of the established piconet through an arbitration slave node of the established piconet. The effect of enabling and when the destination master node of the piconet to which communication is established calls the originating node of the piconet to which communication is not established, establishes that the communication for exchanging the master / slave role with the originating node from the originating node is established. The effect of enabling routing between the two piconets by enabling routing to the destination master node through the piconet's arbitration slave node.

As the communication between the two piconets is enabled, the distance problem due to the limitation of the wireless signal is solved, thereby enabling the communication at a long distance.

In addition, not only the master / slave can be easily switched through the state variables recorded in the control automata of the transmission / reception control unit and the channel state and channel information recorded in the transmission / reception memory, but also the high speed routing can be easily controlled by controlling various states. By doing so, the effect of communication can be made faster.

Claims (5)

In a communication method between two piconets in a Bluetooth scatternet, (a) any source node requesting a page from an arbitration node of a piconet that is in communication reach with the source node; (b) after the arbitration node requests a hold to a destination node of the piconet, a slave response to the page is sent to the source node; And (c) transmitting a data packet from the source node to the destination node through the arbitration node; Communication method between the two piconets comprising a. In a communication method between two piconets in a Bluetooth scatternet, (a) informing the piconet's arbitration node that a destination node of any piconet has a communication request to a source node at a communication reach with the arbitration node of the piconet; (b) after the arbitration node requests a hold to the destination node, requesting a page from the source node; (c) the source node making a slave response to the page to the arbitration node; (d) exchanging roles between the arbitration node and the source node; And (e) transmitting a data packet from the source node to the destination node via the arbitration node; Communication method between the two piconets comprising a. The method of claim 1 or 2, wherein the step of transmitting a data packet to the destination node is (a) the source node sending the data packet to the arbitration node; (b) after the arbitration node requests hold to the source node, requesting release from the destination node; And (c) the arbitration node sending the data packet to the destination node; Communication method between the two piconets comprising a. In a communication device between two piconees in a Bluetooth scatternet, A link manager that receives a connection request between two piconets from an upper host to control lower transmission and reception; Generate and store arbitration node control variables indicative of the role in the left piconet and the role in the right piconet of the arbitration node between the two piconets under the control of the link manager, and control the transceiver and the transmission / reception memory according to the arbitration node variables. A transmission and reception control unit; A transmission / reception memory for storing channel state information, channel device information, and data to be transmitted corresponding to the arbitration node control variable under control of the transmission / reception control unit; A transmitter / receiver configured to read page state, channel device information, and data to be transmitted, according to the control of the transmission / reception controller, to perform page, slave response, hold, hold release, and data packet transmission; Communication device between the two piconets comprising a. A computer-readable recording medium having recorded thereon a program for executing the method of any one of claims 1 to 3.