Method for performing service discovery, network device and computer program element

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a pervasive wireless network, such as the Bluetooth specification (J. Bray, F. Sturman, Bluetooth: Connect Without Cables, in Ref. [1]. Refer to Overview)) to perform service discovery on ad-hoc networks, network equipment, and computer program products.

【0002】

[Conventional technology]

Pervasive Computing is described in Reference [2], "Greeting Service Discovery in Pervasive Computing Environments" (Brent A. Miller, Robert A. Pascoe, Salutation Service Discovery in Pervasive Computing Environments, IBM R Pervasive Computing White Paper, February 2000) is the next stage of development of network computing, which evolved from client-server computing. The advent of new information devices and connection types is spurring new forms of networking. Users of mobile computing devices, such as notebooks, mobile phones, or palmtops, often transfer the data to other mobile or fixed devices, for example, to store, display, print, or transmit data. Need to transfer. To replace the cables previously used to connect the corresponding computing devices, networking systems such as Bluetooth have been created that set up unmanaged dynamic networks, also known as ad hoc networks or pervasive networks.

【0003】

For example, a computing device using Bluetooth technology may set up an ad hoc network, that is, at this stage, initiate a so-called point-to-point piconet or access an already set up ad hoc network. An ad hoc network that has already been set up may be extended from a point-to-point piconet to a point-to-multipoint piconet or scatternet with this access. An important aspect of modern ad hoc networks is that various devices offering different services can access or be accessed through the network. A mobile phone or digital camera may be connected wirelessly to the notebook, and the notebook itself establishes a link to the printer. The device may enter or leave the ad hoc network momentarily. For example, remote controls carried within a building may be sequentially connected to various devices. Subsequently, these devices can be set by the user to the desired operating conditions.

【0004】

Means and technologies for declaring and communicating equipment requirements and services must be provided to the equipment to achieve the optimum configuration of the ad hoc network.

【0005】

Technologies intended to provide the devices, applications, and services that meet in communication settings with the ability to know each other through electronic messages or greetings have been developed, for example, by the Greeting Consortium (see http://www.salutation.org/). Was done. Once the related devices have exchanged information about their capabilities, they may adjust their interactions accordingly. The greeting manager SLM may be incorporated into the Bluetooth protocol stack described below.

【0006】

The Bluetooth protocol stack shown in FIG. 1 and described on pages 4-5 of "Bluetooth Protocol Architecture" in Ref. [4] includes the Bluetooth core protocol 10. These protocols include baseband and link controller protocol 20, link manager LM30, logical link and adaptation protocol LL2CAP40. Together with the radio part 50 and the host controller interface HCI60, they correspond to the physical layer, data link layer, network layer, transport layer, and session layer of the OSI reference model (reference [1]). See page 7). In addition, FIG. 1 shows the telephony control protocol TCS and the cable replacement protocol RFCOM M80. The RFCOMM80 supports a set of object exchange protocol OBEX90, wireless application protocol WAP100, and telephony-controlled AT command 110, based on well-known corporate standard haze smart modem commands.

【0007】

In addition, the Bluetooth core protocol includes the service discovery protocol SDP120. The SDP120 lets you search for information that can be used to configure a stack that supports several end-user applications. Specifically, the service discovery protocol SDP120 can be used to locate services available in the vicinity of the user. Upon locating the available services, the user may choose to use any service. However, the corresponding connection must be established before information can be retrieved from other devices.

【0008】

Query and paging procedures are used to establish new connections. Referring to FIG. 2, the Bluetooth device changes from standby state 200 to page scan (page) substate 210 or query scan (query) substate 220 to scan a page or query message, or establish a new connection. May change to page state 230 or query state 240 to initiate (see the Bluetooth link controller phase diagram on page 98 of reference [3]).

【0009】

Referring to FIG. 5, the device access code DAC and the inquiry access code IAC are used in the paging and query procedures, respectively. Units in page scan substate 210 or query scan substate 220 are correlated to their respective access codes using a matching correlator.

【0010】

The query procedure lets the unit discover what units are in range and what the device address and clock are. Bluetooth systems use query procedures in applications where the destination device address is unknown to the source. In the query substate 220, the unit performing the discovery continuously sends the query message and collects the Bluetooth device addresses and clocks of all the units that respond to the query message. The unit performing the discovery can then change to the page down state 210 and set up a connection to any of the units that responded to the inquiry message, if desired. When performing a successful page attempt, the unit will enter connection state 250 as a master. The unit responding to the page message will enter connection state 250 as a slave.

【0011】

The broadcast query message may include the general query access code GIAC to query the Bluetooth device or the dedicated query access code DIAC to indicate the class of device to respond to.

【0012】

The time interval between scanning activities typically does not exceed 2-3 seconds.

【0013】

In practice, the user may activate a Bluetooth support device, such as a notebook, and start a word processing application. To print out a document, the notebook requires printer service. Therefore, the notebook issues a series of query messages containing the dedicated query access code DIAC. DIAC specifies the required equipment and finally the printer responds using a frequency hopping sync packet FHS containing all the information needed to establish the connection (56 in Ref. [3]). See page).

【0014】

To retrieve information from a remote device, a connection is established by the access procedure described. The services available from the connected remote device or through the connected remote device are then identified by the service discovery protocol SDP120. The service discovery protocol defines the protocols and procedures used by the service discovery application in the local device to locate the services provided by the server application in the remote device, as well as the attributes of these services. The server maintains a list of service records that describe the characteristics of the services associated with the server. Each service record contains information about a single service. As can be seen in FIG. 4, the service record includes at least the service record handle (attribute ID 0x0000) and the service class ID list (attribute ID 0x0001). Other service attributes are optional (see Defining service attributes on page 358, reference [3]).

【0015】

Figure 3 shows the Bluetooth protocol and supporting entities included in the service discovery profile. The service discovery user application 310 in the local device 300 is the service discovery client SDP._CInterface with 320. It is the service discovery server SDP of remote device 340 connected to database DB350 containing a list of service records._SSend a service inquiry to 330 and also SDP_SThis is to receive a service inquiry response from 330. The service discovery entity SDP uses the logical link connection-oriented transport service CO360 and the adaptation entity L2CAP40. The L2CAP40 uses the baseband asynchronous connectionless link ACL380 to ultimately carry the SDP protocol data unit SDPPDU390 shown in Figure 4.

【0016】

After the required service information has been collected, additional connections initiated by the paging process can be set up for the remote device 340. Application 310 sends the request to the link manager LM30 via the host controller interface HCI60. The LM30 sets up the requested connection (see pages 13-16 of reference [1]).

【0017】

As described in detail above, the process of accessing remote device 340 with a query access code and then retrieving information from remote device 340 involves a number of steps that take quite a long time. In an error-free environment, it may take 10 seconds to receive all responses from remote device 340 following an inquiry message. Setting up connection 250 and retrieving information through service discovery procedures is just as time consuming.

【0018】

Using the dedicated query access code DIAC, which indicates the class of device to respond to, instead of the general query access code GIAC can save time.

【0019】

[Problems to be Solved by the Invention]

However, the number of services and devices involved in an ad hoc network is expected to increase significantly, so the time required for service discovery is the time left to actually use the discovered services. It becomes relatively large in comparison. In addition, it is important to note that the device enters and exits the ad hoc network in short time intervals, but may require the use of available services. Therefore, maintaining an updated list of available services is a continuous process. Moreover, communication traffic within such networks is often bursty, so the time for administrative tasks, such as service discovery, may be severely limited to certain time intervals. This is because the devices involved in the communication perform the service discovery procedure with lower priority.

【0020】

To facilitate access to service information, it has been proposed to establish a device in the network that collects all available service information and then allow other devices to retrieve the service information. .. However, this introduces static elements into the dynamic network. Static elements do not fit well into dynamic networks. It would be desirable to provide methods, network equipment, and computer program products that improve the service discovery procedures described above used within pervasive networks. In addition, it would be desirable to transfer service information to devices in a pervasive network or ad hoc network without substantially occupying the capacity of the communication channel. In addition, it would be desirable to avoid downloading the same service information multiple times from devices connected to the network. In addition, it would be desirable to specify the practice of the invention in a system operating according to the Bluetooth standard.

【0021】

[Means for solving problems]

According to the present invention, there is now provided a method of performing service discovery in a pervasive wireless network that includes a plurality of devices including network devices, remote devices, and other devices. In this method, the network device accesses the remote device to obtain information to establish a connection to the remote device, establishes a connection to the remote device, configures a connection to the remote device, and uses the service remotely. Search for information related to the services provided by the device. A feature of this method is that the network device transfers the retrieved information to another network device, which is available to multiple devices connected to the pervasive network based on the information received. Is to update the list of.

【0022】

The method preferably transfers the service information received by the network device acting as the master to the connected network device acting as the slave, and connects the service information received by the network device acting as the slave to act as the master. Includes transfer to network equipment.

【0023】

The method may include sensing traffic on the carrier and the transfer of service information is performed during idle time. Further, the method may include transferring service information over a control channel. In addition, the method transfers service information through a default packet type that is activated for control purposes when user data is not sent within a pervasive network operating according to the Bluetooth standard. May include that. In a preferred embodiment of the invention, the method may include transferring service information over an undefined packet type within a pervasive network operating according to Bluetooth standards. In a particularly preferred embodiment of the invention, the method comprises packing the service information to be transferred into the payload of a packet and passing it to a connected network device.

【0024】

Looking at the invention from another aspect, there is now a wireless network device that performs service discovery within a pervasive wireless network. This device is a means of accessing a remote device to obtain setup information to connect to the remote device over a network and a means of establishing a connection to the remote device and retrieving information related to services provided by the remote device. And the retrieved information is meant to configure a connection to the remote device before using the discovered service. The feature of the wireless network device is that the searched service information is transferred to another device via the network, and the other device facilitates a stored list of services available from the device connected to the network. Includes a service discovery protocol that allows you to update to.

【0025】

The network device preferably includes means for sensing traffic on the carrier and transferring service information during idle time. The network device may include means for transferring service information over the control channel. In a preferred embodiment of the invention, the network device includes means for packing service information into the payload of a packet and delivering the packet to a connected device.

【0026】

Looking at the present invention from yet another aspect, computer program elements including computer program code means are now provided. When loaded into the processor of a data communication network device, this computer program element performs the method of configuring the processor to perform service discovery within a pervasive wireless network as described above. ..

【0027】

This favorably improves the service discovery procedure used within the pervasive network. In addition, it allows the transfer of discovered service information between devices in pervasive or ad hoc networks without substantially occupying the capacity of the communication channel. In addition, this prevents multiple downloads of the same service information from the network device to each server, thereby optimizing the performance of the pervasive network. Further, the service information is distributed in a chain reaction by the receiving device. The present invention is not exclusive and is particularly suitable for systems operating according to the Bluetooth standard.

【0028】

In a preferred embodiment of the invention, the time to configure a connection in a pervasive network is significantly reduced and the availability of all services provided by the connected network device is established in a short time. Therefore, a network device according to the present invention, for example, a remote control carried from one room to another, quickly receives the required service information.

【0029】

Since the traffic on the carrier often appears as a burst, the carrier is sensed in the preferred embodiment and the service information is exposed only during idle time.

【0030】

In pervasive networks operating according to Bluetooth standards, service information is preferably exposed by default packet types, such as NULL, which is activated for control purposes when user data is not sent, or POLL. Will be done. As alternative packets, types with type codes, such as 1100 or 1101, are used, but these are applicable standards and have not yet been defined. The service information is preferably packed into the payload of the packet passed to the connected network device.

【0031】

BEST MODE FOR CARRYING OUT THE INVENTION

Figure 1 shows a Bluetooth protocol stack that includes Bluetooth core protocol 10. The Bluetooth core protocol includes radio portion 50, baseband and link controller protocol 20, link manager LM30, logical link and adaptation protocol L2CAP40, service discovery protocol SDP120. The host controller interface HCI60 connects the host to a Bluetooth system entity, as shown on pages 524-525 of Ref. [3].

【0032】

As mentioned above, FIG. 1 further shows the telephony control protocol TCS70 and the cable replacement protocol RFCOM M80. The RFCOMM80 supports a set of object exchange protocol OBEX90, wireless application protocol WAP100, and telephony-controlled AT command 110, which is the means by which application 130 accesses the Bluetooth network.

【0033】

Pervasive or ad hoc networks, such as networks operating according to Bluetooth standards, provide access to a variety of devices that offer different services. These networks perform a service discovery or greeting protocol that causes a server connected to the network to retrieve service information. The service information can be used to form a stack that supports several end-user applications.

【0034】

FIG. 2 shows a phase diagram of the Bluetooth link controller including query state 240. The inquiry state 240 may be entered from the standby state 200 or the connection state 250. In query state 240, the bluetooth device broadcasts an inquiry message, and the referral message is sensed by the bluetooth device in query scan state 220. Upon receiving an inquiry message containing the general or dedicated inquiry access code GIAC or DIAC, the remote network device may respond using the frequency hopping synchronization packet FHS. The FHS contains all the information needed to establish a connection. Thus, the Bluetooth device may change from query state 240 to page state 230 to establish a connection 250 to the remote device. The remote device receives the page message when it enters the page scan state 210 and participates in the communication as a slave.

【0035】

Referring to FIG. 3, the local device 300 is connected to the remote device 340 as described above. Service discovery entity SDP for local device 300_C320 is the service discovery entity SDP of remote device 340 to retrieve the required service information._SConnected to 330 as a client.

【0036】

The query, setup, and service discovery procedures described above are detailed in Figure 4. After the query and page transactions, the client CL400 link manager LM30 sets up the connection. Logical channels are provided by logical links and entities working according to the adaptation protocol L2CAP40. L2CAP40 is a service discovery protocol SDP_CAdapted to 320. An SDP protocol data unit as described on pages 344-345 of Ref. [3] to retrieve service information from the database DB350, specifically the service list SLIST420 of the server SR410 stored in the database DB350. But the service discovery peer entity SDP_C320 and SDP_S Exchanged with 330. The connection is terminated after the service records contained in list SLIST420 have been downloaded. A new connection may be set up and configured to use the services provided by server SR410.

【0037】

As mentioned above, the process of accessing remote device 340 via general query access code GIAC or dedicated query access code DIAC and then retrieving information from remote device 340 is a number of processes that take a considerable amount of time. Including steps.

【0038】

A method of the present invention designed to improve known service discovery procedures will now be described with reference to FIG.

【0039】

FIG. 6 shows a wireless local area network 600, eg, an ad hoc network WLAN included in an office. The wireless local area network 600 includes a first notebook CL1 610 that acts as a master for the camera SR3 620 and a slave for the second notebook computer CL2 630. The notebook computer CL2 630 acts as a master for the facsimile machine SR6 640, the beamer SR5 650, and the permanent standard personal computer SR4 660 connected to the Internet 670.

【0040】

As mentioned above, the device sporadically enters and exits the ad hoc network, while the ad hoc network self-configures its connection according to the sporadic entry and exit of the device. According to a preferred embodiment of the invention, this is done in three steps. If a mobile phone SR2 680, which may belong to the owner of notebook CL1 610, is brought into the office in query scanning state 220, the mobile phone SR2 680 detects a query message from notebook CL1 610 and detects it. It will respond using a frequency hopping synchronized packet FHS. The notebook CL1 610 may then change to page state 230 and set up a connection to the mobile phone SR2 680. The mobile phone SR2 680 detects a page message while in page scan state 210. The notebook CL1 610, working as a client, will then search for information related to the services provided by the mobile phone SR2 680.

【0041】

Now referring to Figure 7, the notebook CL1 610 then changes to the PUBLICATION state 700 after discovering the service information. In the public state 700, the discovered service information is published and actively transferred to other network devices, the camera SR3 620, and the notebook CL2 630 to which the notebook CL1 610 is connected. This step prevents the same service information from the mobile phone SR2 680 from being downloaded multiple times. It should be noted that the public state 700 is similar to the connection state 250, except that the POLL and null packets in the connection state 250 are replaced by the POLL public and null public packets in the public state 700. These will be explained more briefly. The public state 700 may be considered as a subset of the connection state 250.

【0042】

The service information published by the notebook CL1 610 and transferred to its master notebook CL2 630 and its slave camera SR3 620 is sent to the notebook CL2 630 by the receiving devices CL2 630 and SR3 620. It is also transferred to the connected network devices SR4 660, SR5 650, and SR6 640 acting as slaves, or to other network devices (not shown) acting as masters for the camera SR3 620.

【0043】

Therefore, the information rapidly distributed over the ad hoc network allows the necessary adjustment of configuration settings when changes occur in the network.

【0044】

Before the publication is performed, the associated device can preferably sense traffic on available carriers so that service information is forwarded, for example, during idle times between bursts. Therefore, the discovered service information can be published without placing an additional load on the network system.

【0045】

The transfer of discovered service information is possible via the user channel, but the information is preferably exposed via the control channel.

【0046】

In pervasive networks operating according to Bluetooth standards, service information is preferably activated by default packet types, such as NULL and, or POLL, which are activated for control purposes when user data is not sent. Transferred.

【0047】

The packet types used in Bluetooth piconet are described on pages 54-58 and 81-84 of Ref. [3]. For asynchronous connectionless links, the default type is always null packets for masters and slaves. Null packets can be used by the master to allocate the next time slot from slave to master to the addressed slave. The addressed slave is not forced to respond to null packets. If the master needs a response, it will send a POLL packet.

【0048】

In addition, Bluetooth systems may be enhanced by undefined type codes such as 1100 or 1101 for synchronous connection oriented SCOs or asynchronous connectionless link ACLs. Therefore, type code 1100 could be defined as a null public packet and type code 1101 could be defined as a POLL public packet. Thus, the receiving network device will be able to identify the improved NULL and POLL packets and unpack the enclosed service information from the payload segment.

【0049】

As mentioned above, the present invention can be advantageously used in ad hoc or pervasive networks operating according to the Bluetooth standard. However, as will be appreciated, the methods of the invention can also be used in other wireless networks that perform service discovery procedures (Chapter 32, 32-1 to 32-14, Ref. [5]). See).

【0050】

The present invention may be applied in a network device without changing the hardware. A network device that is already in operation in the field may be easily updated by a computer program product including a recording medium that stores a computer program that embodies the example of the present invention described above. Alternatively, such computer program products or elements may be loaded into network equipment via a data communication network connection.

【0051】

In short, according to an exemplary embodiment of the invention, a method of performing service discovery on a pervasive wireless network (WLAN) operating according to a standard such as the Bluetooth standard, a wireless network device, and a computer program element. Was explained. These methods, the wireless network device, and the computer program element put the network device (CL1) in a primary state to access the remote device (SR2) to obtain (a) connection setup information (a). b) Set up a connection to the remote device (SR2) and put it in a second state to search for information related to the services provided by the remote device (SR2), and the information found goes to the remote device (SR2). Necessary for configuring the connection to use related services, (c) device (CL1) publishes the retrieved service information and actively transfers it to other devices (CL2, SR3). Access protocol and service discovery protocol that update the list of services available from the device (CL, SR) connected to the Pervasive Network (WLAN) in the state of 3 and other devices (CL2, SR3). including.

【0052】

References [1] "Bluetooth: Connect Without Cables, Prentice Hall Inc., New York 2001" (J. Bray, F. Sturman, Bluetooth: Connect Without Cables, Prentice Hall Inc., New York 2001) [2] "Greeting Service Discovery in a Pervasive Computing Environment" (Brent A. Miller, Robert A. Pascoe, Salutation Service Discovery in Pervasive Computing Environments, IBM R Pervasive Computing WhitePaper, February 2000) [3] "Specification of the Bluetooth System, Volume 1, Core, Version 1.0B, issued by the Special Interest Group (SIG) on December 1, 1999" ) [4] "Bluetooth WHITE PAPER, Bluetooth Protocol Architecture, Version 1.0, issued by the Special Interest Group (SIG) on August 25, 1999) [5] "Mobile Communication Handbook" (Jerry D. Gibson, THE MOBILE COMMUNICATIONS HANDBOOK, CRC PRESS, Boca Raton 1999, 2^ed Edition) [0053]

In summary, the following matters will be disclosed with respect to the constitution of the present invention. (1) A network device (CL1) includes a plurality of devices (CLn, SRn) including a network device (CL1), a remote device (SR2), and other devices (CL2, SR3), and the network device (CL1) is transferred to the remote device (SR2). To access the remote device (SR2) to obtain information about establishing a connection to, establish a connection to the remote device (SR2), configure a connection to the remote device (SR2), and use the service. A method of performing service discovery on a pervasive wireless network (WLAN) that retrieves information related to the services provided by (SR2), where the network device (CL1) uses the retrieved information on other networks. Services available from multiple devices (CLn, SRn) that are transferred to a device (CL2, SR3) and connected to a pervasive network (WLAN) based on the information received by other devices (CL2, SR3). A method characterized by updating the list of. (2) The service information received by the network device (CL2) acting as a master is transferred to the connected network device (SR4, SR5, SR6) acting as a slave, and received by the network device (SRn) acting as a slave. The method according to (1) above, comprising transferring service information to a connected network device (CLn) acting as a master. (3) The method according to (1) or (2) above, wherein the transfer of service information is performed during idle time, including sensing traffic on the carrier. (4) The method according to any one of (1) to (3) above, which comprises transferring service information via a control channel. (5) In a pervasive network operating according to the Bluetooth standard, including forwarding service information through a default packet type activated for control purposes when user data is not sent, The method according to any one of (1) to (4) above. (6) The method according to any one of (1) to (4) above, which includes transferring service information via an undefined packet type in a pervasive network operating according to the Bluetooth standard. .. (7) The method according to (5) or (6) above, which comprises packing the service information to be transferred into the payload of the packet and passing it to the connected network device (CLn, SRn). (8) A wireless network device (CL1) that performs service discovery on a pervasive wireless network (WLAN), and the device is (a) connected to a remote device (SR2) via the network (WLAN). Find the means to access the remote device (SR2) to get the information to set up, and (b) establish a connection to the remote device (SR2) and search for information related to the services provided by the remote device (SR2). The network device (CL1) is a network device (CL1), provided that the means and the information retrieved is for configuring a connection to a remote device (SR2) before using the discovered service. Information is transferred to other devices (CL2, SR3) via the network, and the other devices (CL2, SR3) store the services available from the devices (CLn, SRn) connected to the network (WLAN). A network device characterized in that the created list can be easily updated. (9) The network device (CL1) according to (8) above, which includes means for sensing traffic on the carrier and transferring service information during idle time. (10) The network device (CL1) according to (8) or (9) above, which includes means for transferring service information via a control channel. (11) The network device (CL1) according to any one of (8) to (10) above, which includes a means for packing service information in a packet payload and delivering the packet to a connected device. (12) A computer program element including computer program code means, which, when loaded into the processor of a data communication network device, constitutes the processor and is any one of (1) to (7) above. A computer program element that performs the method described in the section.

[Simple explanation of drawings]

[Figure 1]

It is a block diagram of the Bluetooth protocol stack.

[Figure 2]

It is a state diagram of the Bluetooth link controller.

[Fig. 3]

It is a block diagram of the Bluetooth protocol and the support entity included in the service discovery protocol.

[Fig. 4]

FIG. 6 is a block diagram showing query, link setup, and service discovery messages exchanged between a client and a server.

[Fig. 5]

It is a block diagram of a bluetooth packet.

[Fig. 6]

It is a block diagram which shows the pervasive network which includes a plurality of network devices which embodied this invention.

[Fig. 7]

Other phase diagrams of the Bluetooth link controller.

[Explanation of symbols]

10 Bluetooth core protocol 20 Baseband and link controller protocol 30 Link Manager LM 40 Adaptation Entity L2CAP 50 wireless parts 60 Host Controller Interface HCI 70 Telephony Control Protocol TCS 80 Cable Replacement Protocol RFCOMM 90 Object Exchange Protocol OBEX 100 Wireless Application Protocol WAP 120 Service Discovery Protocol SDP 130 application 200 Standby state 210 page scan (page) lower state 220 Query scan (query) lower state 230 page state 240 Query status 250 connection status 300 local equipment 310 Service Discovery User Application 320 Service Discovery Client SDP_C330 Service Discovery Server SDP_S340 remote device 350 database DB 360 Connection Oriented Transport Service CO 380 Baseband Asynchronous Connectionless Link ACL 390 SDP Protocol Data Unit SDP PDU 400 client CL 410 Server SR 420 Service List SLIST 600 Wireless Local Area Network 610 Notebook CL1 620 camera SR3 630 Notebook Computer CL2 640 Facsimile device 650 beamer 660 standard personal computer SR4 670 internet 680 Mobile Phone SR2 700 public status