KR100538946B1 - Wireless communication method capable of connectionless broadcast - Google Patents

Abstract

A wireless communication method capable of connectionless broadcast is disclosed. The wireless communication method includes the steps of: (a) generating a broadcast data packet including synchronization information for synchronization with at least one or more receivers, and broadcast data; and (b) broadcasting the synchronization information with the receiver. Synchronizing channels, and (c) sending the broadcast data packet to the receiver. As a result, broadcast data can be quickly transmitted to the receiver without wasting time passing through the connection establishment procedure.

Description

Wireless communication method capable of connectionless broadcasting

The present invention relates to a wireless communication method capable of connectionless broadcast, and more particularly to a wireless communication capable of connectionless broadcast capable of transmitting broadcast data before a connection establishment procedure in a Bluetooth system. It is about a method.

Bluetooth was originally developed to eliminate cables connecting devices such as mobile phone handsets, headsets, and portable computers, and is a low cost, low power, short range wireless technology. However, by enabling standardized wireless communication between Bluetooth devices, Bluetooth has created the concept of a personal area network (PAN), which is a kind of short-range wireless network. Bluetooth operates using the 2.4GHz unlicensed Industrial, Scientific and Medical (ISM) band, and the Bluetooth device that initiates data exchange in the network created by the Bluetooth is called a master, and the Bluetooth device that responds to the master is called a slave ( slave). One master can connect with up to seven active slaves. In this way, a network in which one or more slaves are connected to one master through a connection establishment procedure is called a piconet.

On the other hand, Bluetooth terminals (PAN User: PANU) that supports the Bluetooth PAN profile (pan user) needs to collect location information from the Bluetooth network access point (hereinafter referred to as "NAP"). As Bluetooth terminals move, the number of Bluetooth terminals in charge of one NAP changes from time to time. Therefore, NAPs periodically broadcast information of Open System Interconnection (OSI) Layer 2 (Data link layer) and Layer 3 (Network layer). It is necessary to do According to the Bluetooth standard document, Bluetooth is a connection-oriented method that takes a lot of time to set up a connection such as inquiry, inquiry scan, page, page scan, etc. before data transmission. connection oriented) system. Therefore, transmission of information through broadcast is also possible only after the connection setup is completed between Bluetooth devices constituting one piconet.

In addition, Bluetooth terminals use a lot of radio resources for the handover (handover) that occurs when moving from one piconet to another. For example, in voluntary handover, some NAPs must perform a calling procedure for handover to only one Bluetooth terminal. During this call process, NAPs must interrupt the service for a long time for Bluetooth devices that are connected and receiving services. This interruption of service makes it impossible to support real-time services. However, since most Bluetooth terminals are in an idle state, performing a handover every time the Bluetooth terminal moves is a waste of resources. This is because it is enough for NAP to know the approximate location of the Bluetooth terminal in the idle state.

The Bluetooth PAN Working Group or the Local Positioning Working Group addresses the need for much information to be exchanged and broadcast before the master and slave are determined. However, as described above, in order to broadcast information in a Bluetooth system, since a piconet consisting of a master and a slave is possible only under a determined situation, a method for supporting broadcast before a connection establishment procedure is required.

To this end, Philips has proposed a way to extend the ID packet to broadcast local position during the inquiry process. However, this method causes a problem when broadcast information is delivered in pieces. That is, the location information included in the extended ID packet (Extended Identifier) is 300 bytes, and by the IP layer handover protocol, the access point should periodically broadcast an advertisement message. The question arises: how to efficiently arrange cast messages.

The Philips proposal also has the problem of spending too much time because each slot packet must be repeated every 16 hopping frequencies. In addition, since it is necessary to synchronize with NAP and receive information by receiving an extended ID packet, even if only one packet is received incorrectly, information contained in the packet is lost, compared to the case of receiving information after synchronization, and thus the entire broadcast information is received. Reassembly becomes impossible.

To solve this problem, Widcomm proposed a method of adding a Bluetooth device address (hereinafter referred to as 'BD_ADDR') of the NAP to the extended ID packet. According to this, the Bluetooth terminal receiving the extended ID packet can synchronize with the corresponding NAP using the BD_ADDR and the clock information included in the extended ID packet, thereby supporting fast handover. However, even in this method, since the Bluetooth terminal must perform a response to the ID packet received to establish a connection, there is a problem that it still takes a long time until the data transmission is possible.

In order to solve the various problems as described above, the present applicant has filed a patent for the 'connection-free wireless communication device and method thereof' of the domestic application number 2002-63829. The present invention discloses a wireless communication device capable of broadcasting without a connection establishment procedure using a broadcast channel including a beacon window and a broadcast window, and a method thereof.

However, the conventionally proposed method has a problem in that there is a limit in the size of data that can be transmitted through broadcast by using a method of synchronizing basically using an ID packet. Therefore, there is a problem that a user must proceed with the entire connection setup procedure to obtain more information.

The present invention has been made to solve the above problems, and an object of the present invention is to enable a connectionless broadcast that can broadcast a large amount of information prior to a connection establishment procedure in a Bluetooth system, and connection establishment In this case, the present invention provides a wireless communication method capable of connectionless broadcasting that can perform a connection establishment procedure quickly.

A wireless communication method capable of connectionless oriented broadcast according to the present invention for achieving the above object, (a) generates a broadcast data packet including synchronization information for synchronization with at least one or more receivers, and broadcast data; (B) synchronizing the channel with the receiver by broadcasting the synchronization information, and (c) transmitting the broadcast data packet to the synchronized receiver.

Preferably, the method further includes (d) executing a connection window for establishing a connection with a receiver requesting a connection. In this case, step (d) preferably includes receiving an LMP message from the receiver requesting the connection, and establishing a connection by exchanging a POLL packet with the receiver requesting the connection.

Preferably, the synchronization information and the broadcast data packet are transmitted through a beacon window and a data window. The synchronization information can be delivered by a BID (Broadcast IDentifier) packet.

Preferably, the BID packet is configured to include a Bluetooth device address (BD_ADDR) and clock information. The BID packet further includes at least one of the data window configuration information, the location information of the connection window, and an error check. It is desirable to. In this case, the data window setting information preferably includes at least one of an ACL packet type, a repetition number, a broadcast profile, and an offset of data. In addition, it is preferable to transmit and receive data with the receiver using a Bluetooth protocol.

Hereinafter, with reference to the drawings will be described the present invention in more detail.

1 illustrates a wireless communication environment to which a wireless communication method capable of connectionless broadcasting according to the present invention is applied. As shown in the figure, the wireless communication environment to which the present invention is applied is composed of one sender 10 and a plurality of receivers 30a to 30n. In this configuration, the sender 10 can access a connectionless broadcast channel without going through the usual connection establishment procedures such as inquiry, inquiry scan, page, page scan, and the like. Can be used to broadcast data to senders 30a-30b.

2 is a diagram illustrating a hierarchical structure and time information of a connectionless-oriented broadcast channel used in a wireless communication method capable of connectionless broadcasting according to the present invention. As shown in the figure, a connectionless broadcast channel is composed of a beacon window, a data window, and a connection window. The beacon window is used for synchronization and contains an index to the data window following the beacon window. Data windows are used to broadcast user-defined data from various profiles. The connection window is optional, and if a connection is required, it is performed at the request of the device to perform the connection procedure immediately without going through the inquiry and call procedure. In beacon and data windows, the master-slave (M-S) slot is used by the sender, and in the connection window, the slave-master (S-M) slot is used by the receiver requesting a connection.

In beacon windows, Broadcast ID (BID) packet trains are transmitted on different frequency hops during the master-slave (M-S) slots. As shown in the figure, the BID packet train includes Train A and Train B. Similar to the inquiry procedure, Train A and Train B last for 22.5 ms, each processing 16 frequency hops. Each packet train repeats for 1.28 s, so the beacon window lasts for 2.56 s.

The BID packet train in the beacon window may not be contiguous. In other words, higher priority traffic packets such as a SCO link or an eSCO link may be inserted therebetween. The BID packet is a newly defined 1 slot packet and may include an information field of up to 240 bits. The BID packet contains items such as synchronization information, configuration of the data window, location of the connection window, error checker, and the like. Table 1 below shows information included in a BID packet.

   Item  Bit size Sync data  BD_ADDR 32  Clock 28 Organization of Data Window  ACL packet type  Number of iterations  Broadcast profile 8  The offset of the data 10 Location of Connection One Window  offset 8 Error check  FEC 2/3  CRC check 8

In the item of Table 1, BD_ADDR and clock are items included in the BID packet. However, the ACL packet type and the number of repetitions are used when the ACL packet type is used for the data window. The broadcast profile and data offset indicate the broadcast data service type and its service offset. If 8 bits are allocated to the broadcast profile item, all 256 service types can be defined. The offset field indicates the offset position of the connection window when the connection window is used. The FEC and CRC check fields are used for error correction.

3 is a view showing the configuration of the beacon window. As shown in the figure, a receiver capable of receiving opens a scan window and listens to one or two frequency hops. As defined in Bluetooth standard 1.2, if the dual scan is supported, the size of the scan window is doubled to 22.5 ms. In this case, during the first half window, the receiver listens to the frequency hop of train A and listens to the frequency hop of train B for the other half window. The maximum scan interval is 2.56 s, and the receiver does not need to send anything, so there is no limit to the number of receivers. The receiver receiving the BID packet in the beacon window extracts and synchronizes the clock with the BD_ADDR from the BID packet.

4 is a diagram illustrating a configuration of a data window. In Fig. 4, data windows divided in different profiles are shown. The ACL data type and the number of iterations of the packet are defined in the beacon window. If there is not enough space to accommodate broadcast data from all profiles, it is configured differently from neighboring unconnected broadcast channels to serve different profiles. The receiver's frequency hop is the same as in the connected state. Data is partitioned or encapsulated into Logical Link Control and Adaptation Protocol (L2CAP) ACL packets.

If there is no connection request from the receiver, when the beacon window and the data window are terminated, the procedure of the unconnected broadcast ends. In this case, since no packet is transmitted to the sender at the receiver side, the slave-master (S-M) slots of the beacon window and the data window can be used to perform a general connection procedure of devices wishing to participate in the piconet.

6 is a message sequence chart (MSC) for explaining an operation method of a wireless communication method capable of connectionless broadcasting according to the present invention.

Referring to FIG. 6, as described above, the transmitter generates a BID packet including synchronization information for channel synchronization and broadcasts it to each receiver through a beacon window (S100 and S110). This process is repeated several times (S120, S130).

Recipients receiving the BID packet synchronize with reference to the BD_ADDR and the clock information included in the BID packet, and extract the information on the configuration of the data window to determine the configuration of the data window. If the receiver wants to connect with the sender, the receiver responds by transmitting a Frequency Hop Synchronization (FHS) packet to the sender (S140). In this case, a random number is generated between 0 and RANDMAX, and responds in a backoff manner until the beacon window and the data window are terminated, in order to prevent message collision between different receivers. If the receiver receives a general ID packet instead of a BID packet, the receiver may recognize this as a general inquiry procedure and perform a procedure accordingly.

When the beacon window ends and the data window starts, data packets from different profiles are transmitted from the sender to the receiver, such as broadcast in the piconet (S200, S210, S220, S230). At this point, the sender behaves like a master and the receiver behaves like a slave. Data is partitioned or encapsulated into L2CAP ACL packets. At this time, PSM (Protocol / Service Multiplexor) is used to indicate that the connectionless broadcast data. During the connectionless broadcast, the receiver's response is not needed, the receiver just extracts the data of interest and ignores the rest. If no applications are of interest, or no connection data is received from the same sender, the original state is maintained. At the same time, the slave-master (S-M) slot of the data window may be used for connection request from the receiver. In this case, the receiver must check whether the last master-slave slot is used by unconnected data packets. The receiver can know this by monitoring the PSM of the L2CAP packet.

When there is a connection request from the receiver, the receiver must decide whether to start the connection window, as shown in FIG. 5, next to the data window. That is, when the sender wants to connect, a new Link Management Protocol (LMP) message is transmitted to the receiver (S300), and the connection window is started. If the sender does not want to connect, such as when there are not enough resources, the LMP message is not sent to the receiver.

The LMP message includes BD_ADDR and AM_ADDR (Active Member ADDRess). After the transmission of the LMP message, the receiver transmits an ID packet including a device access code (DAC), which is a code for identifying a specific device, to the sender (S310). After the sender receives the ID packet from the receiver, the POLL packet is exchanged to confirm the connection (S320). Thereafter, the receiver becomes a master in the piconet, and the receiver becomes a slave and a slave packet is transmitted (S330). Thus, the recipient joins the piconet without inquiry or call procedure. The connection window ends when the first link data from the sender is sent to any slave. Thus, if more than one receiver requests a connection, the sender must establish a connection window with all receivers that want to connect before sending the ACL packet. If after the connection window, the receiver still wants to connect, a procedure may be performed in which the receiver calls the sender.

7 is a message sequence chart showing a case in which only a beacon window and a data window are used for broadcasting. In this case, it operates in the same manner as described in FIG. 6 except that the connection window is not used because there is no connection request from the receiver.

By the above process, it is possible to quickly transmit broadcast data without a connection establishment procedure. In addition, since the present invention uses the newly defined BID packet, the general Bluetooth device does not affect the existing Bluetooth communication by discarding the packet without any response. In the wireless communication method according to the present invention, if a general inquiry message is received during the beacon window, an operation corresponding to the existing Bluetooth protocol is performed, and thus no problem occurs in communication with a Bluetooth device that complies with the existing Bluetooth protocol. Do not.

As described above, according to the present invention, a broadcast channel including a beacon window, a data window, and a connection window can be used to broadcast data without going through a connection setup procedure. Accordingly, broadcast data can be quickly delivered without wasting time required for the connection establishment procedure. And, if a connection is required, the connection is possible through the connection window.

In addition, although the preferred embodiment of the present invention has been shown and described above, the present invention is not limited to the specific embodiments described above, but the technical field to which the invention belongs without departing from the spirit of the invention claimed in the claims. Of course, various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

1 is a view illustrating a wireless communication environment to which a wireless communication method capable of connectionless broadcasting according to the present invention is applied;

2 illustrates a hierarchical structure and time information of a broadcast channel;

3 is a view showing the configuration of a beacon window,

4 is a diagram showing the configuration of a data window;

5 is a diagram illustrating a configuration of a connection window; and

6 and 7 are message sequence charts provided for explaining a wireless communication method capable of connectionless broadcasting according to the present invention.

Explanation of symbols on the main parts of the drawings

10: sender 30a to 30n: receiver

Claims (9)

(a) generating a broadcast data packet comprising synchronization information for synchronization with at least one or more recipients, and broadcast data; (b) synchronizing a channel with the receiver by broadcasting the synchronization information; And and (c) transmitting the broadcast data packet to the synchronized receiver. The method of claim 1, and (d) executing a connection window for establishing a connection with a receiver requesting a connection. The method of claim 2, Step (d) may include receiving an LMP message from a receiver requesting the connection; And And establishing a connection by exchanging a POLL packet with a receiver requesting the connection. The method of claim 2, And the synchronization information and the broadcast data packet are transmitted through a beacon window and a data window, respectively. The method of claim 4, wherein The synchronization information is a wireless communication method capable of unconnected broadcast, characterized in that transmitted by the BID (Broadcast IDentifier) packet. The method of claim 5, The BID packet may include a Bluetooth device address (BD_ADDR) and clock information. The method of claim 6, The BID packet may further include at least one of the data window configuration information, the location information of the connection window, and an error check. The method of claim 7, wherein The data window setting information may include at least one of an asynchronous connectionless (ACL) packet type, a repetition number, a broadcast profile, and an offset of data. The method of claim 1, Wireless communication method capable of connectionless broadcast, characterized in that the data transmission and reception with the receiver using a Bluetooth protocol.