KR100703586B1 - Method and apparatus for effecting a handoff between two ip connections for time critical communication - Google Patents

Abstract

A wireless communication unit 800 and a wireless communication method 900 for achieving handoff from a first internet protocol (IP) connection 221 to a second IP connection 331 for time critical communication are disclosed. The method includes communicating (905) between a first wireless station and a second station (331) using a first IP address (223) and a first IP connection for a first wireless station; Setting up a second IP connection with a second IP address for a first wireless station, wherein the first IP connection is a primary connection and the second IP connection is a secondary connection; Determining (915) a second IP connection to be a primary connection; And changing (917) the second IP connection to the first connection by notifying the second station that the second IP address is the primary address using stream control transfer protocol (SCTP) messages.

Handoff, IP Connection, SCTP Message, Wireless Communication Unit

Description

METHOD AND APPARATUS FOR EFFECTING A HANDOFF BETWEEN TWO IP CONNECTIONS FOR TIME CRITICAL COMMUNICATION}

The present invention relates generally to communication systems, in particular to methods and apparatus for achieving handoff of time critical communications from one IP connection to another.

As is very evident in wireless communication systems, communication systems are known and continue to evolve rapidly. Internet or Internet using IP address and various packet data transport protocols such as Internet Protocol (IP), Transport Control Protocol (TCP), Universal Datagram Protocol (UDP), and more recent Stream Control Transport Protocol (SCTP) Systems are being deployed that allow packet data enabled mobile stations to access packet data networks such as Internet like networks. Many second and third generation cellular and cellular systems, such as general packet radio service (GPRS), code division multiple access (CDMA) 2000, broadband CDMA, universal mobile telecommunications service (UMTS), Rely on or support them. The cellular systems are typically arranged and configured to provide a handoff transparently or with little or no user indication to the user of the system for communication from a fixed point of one cell to another.

Other communication systems are well received and are characterized by small or local area wireless systems that provide services to users after proper authorization and authentication processes have succeeded. The wireless systems are systems designed based on IEEE 802.11. These systems are designed at low cost and are intended to eliminate most of the connections and cables. Thus, most of these systems do not deal with mobility issues such as handing off a communication from one fixed or access point to another during communication, and moreover accept or initiate handoffs between cellular systems or cellular systems. Nor do. If the fixed points are part of the same subnet called the basic service set or BSS in an 802.11 system, some 802.11 systems have the ability to pick up communications that drop one fixed point from another fixed point, but this is a matter of seconds Is not suitable for dealing with mobile users who have a time-consuming and real-time or time threshold requirement.

Obviously there is a need for methods and apparatuses for achieving handoff of time critical communications from one IP connection to another. Preferably, this is obvious to systems, network operators, and users and will use SCTP technology.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings in which like reference numbers are incorporated in part of the specification, together with the following detailed description, and in which in some drawings, like reference numerals represent the same or functionally similar elements, further illustrate all the various embodiments according to the present invention, To illustrate these and advantages.

1 shows, in simplified form, a system level diagram of a communication system using a stream control transport protocol to support multiple connections between stations.

2-4 are system level diagrams illustrating a preferred embodiment for handing off communications between two wireless IP access points using two wireless IP access points in accordance with the present invention.

5-7 are system level diagrams illustrating another embodiment of handing off communications between two IP connections using a cellular system and a wireless IP access point in accordance with the present invention.

8 is a functional block diagram of a preferred embodiment of a wireless communication unit suitable for using the systems of FIGS. 2-7 in accordance with the present invention.

9 is a flow diagram of a preferred method of handing off time critical communications between two IP connections in accordance with the present invention.

The present disclosure generally relates to wireless communication units or more specifically to communication systems providing service to users operating therein. In particular, various inventive concepts and principles are disclosed and discussed that are implemented as methods and apparatuses for achieving handoff of time critical communications from one IP connection to another using SCTP messages. Of particular interest are communication systems that are at least partially wireless and are capable of solving mobility problems within local area systems and between other systems, such as local area and cellular systems, code division multiple access (CDMA), and GPDMA (code division multiple access). (2000), such local area systems and 802.11 local area systems are being developed and deployed with second and third generation cellular and cellular systems such as broadband CDMA, Universal Mobile Telecommunications Service (UMTS).

As discussed further below, various inventive principles and combinations thereof are employed to ensure that endpoints or stations in communication are transparent to the user and user communications, without further intervention of system elements or equipment. Known systems, in the premise that the principles and equivalents of the present invention are utilized, thus inducing to establish alternative IP connections, which can be used as required to perform a handoff when needed or desired. Various problems related to are alleviated.

The present disclosure is provided to further explain in a manner enabling the best mode of forming and using various embodiments in accordance with the present invention. The present disclosure is provided to enhance the understanding and appreciation of the principles and advantages of the present invention, rather than limiting it in any way. The invention is limited only by the appended claims, including all equivalents of the patented claims and any corrections made during the progress of this application.

The use of relative terms such as first and second, top and bottom, etc., does not necessarily require or involve any actual said relationship or order between the entities or actions and from other entities or actions. It is further understood that it is only used to distinguish. Many of the functions of the present invention and many of the principles of the present invention are best implemented with integrated circuits (ICs) and software programs or instructions, such as application specific ICs. Although guided by the concepts and principles disclosed herein, even considering the many efforts and many design choices arising, for example, due to available time, current technology, and economic considerations, those skilled in the art will appreciate It is anticipated that the instructions and program and ICs can be easily generated. Therefore, in view of simplifying and minimizing any risk of obscuring the principles and concepts according to the present invention, further discussion of the software and ICs will be limited to those necessary in relation to the principles and concepts in the preferred embodiments. .

Referring to FIG. 1, a simplified and exemplary system level diagram of a communication system using a stream control transport protocol to support multiple IP connections between stations, in particular station A 103 and station B 105, is discussed and discussed. Will be described. In FIG. 1, station A 103, shown as a mobile wireless communication unit, such as a cellular or subscriber handset or messaging unit, is shown as a portable laptop computer via a first network 107 and a first IP connection 109. Communicating with 105, station A has a first IP address IP A1 111 and station B has a first IP address IP B1 113. Station A and station B also share a second IP connection 115 through the second network 116, where station A has a second IP address IP A2 117 and station B has a second IP address IP B2 ( 119). The third IP connection 121 is shown as station A uses its second IP address IP A2 117 and station B uses its third IP address IP B3 123.

The multiple access arrangement is made using a relatively new transport protocol known as the Stream Control Transport Protocol (SCTP), which was recently standardized by the Internet Engineering Task Force (IETF). It works on the same layer as TCP and UDP and can be seen to have more capabilities than the TCP version. SCTP is designed to ensure that streams do not block each other by providing a way for applications on an endpoint or station to manage simultaneous and reliable streams with other stations. SCTP can mix the best streams with reliable streams. SCTP is also expected to increase availability by enabling one station to specify to another endpoint or station that it has more than one IP destination address. The other endpoint will select one of the addresses as the first destination address. When that address fails, the SCTP layer will automatically switch to another destination address. Switching does not require any help from applications using the SCTP layer. Especially when using alternate networks whose alternate address is different, the system reliability is much higher. However, SCTP fail-over switching can take several seconds and the present disclosure discusses and discloses various concepts and principles that will address these problems. This is too slow for time critical communications such as voice or video.

SCTP does not allow an endpoint, such as station A or B, to change the address provided to another endpoint without first suspending and reinitializing the IP connection. It is also not possible to specify which address should be used by another endpoint as the first destination address. SCTP is being extended to allow operators to change IP devices in stations or endpoints without having to reinitialize SCTP transports (see draft-ietf-tsvwg-addip-sctp-0.3.txt). The IETF draft defines SCTP extension messages that an endpoint can use to inform other endpoints that the destination address will be deleted, the destination address will be added, or that the specified address will be used as the first destination address. . These SCTP extension messages can be used in a new and desirable way to support and implement timed handoffs between IP connections. The co-pending patent application, a method and apparatus for achieving continuous handoff between IP connections, named Dorenbosch et al., Assigned to the same assignee with a similar filing date, includes a station using TCP / UDP using a gateway and Discuss new and progressive techniques for achieving handoffs. Here we discuss and describe various aspects of the new and progressive technology to achieve handoff between stations using SCTP methods.

With reference to FIGS. 2-4, system level diagrams illustrating handoff of communication between two wireless IP connections using two wireless IP access points will be described and discussed. It is anticipated that various access points in accordance with various standards and technologies, such as Hyperlan, Bluetooth, other local area network technologies, etc., will be used to achieve handoff in or between respective systems or networks. However, the application will focus on the prerequisites for doing so and the preferred embodiment using an IEEE 802.11 network. With reference first to FIG. 2, some definitions and terms that generally apply to 802.11 networks will be described.

Wireless IP using 802.11 is growing in popularity. For example, many popular coffee shops offer 802.11b connections to their customers. Customers can enjoy the latte, browse the Internet or the company's intranet, read and respond to email. Wireless IP may provide real time services such as voice over IP and video conferencing. The 802.11 coverage area is called a basic service set (BSS) such as BSS A 203 and B22 B 205. The 802.11 standard supports a separate BSS with an ad-hoc network of mobile stations, but a typical BSS may bridge other Internet and wired LANs, such as distribution system 213 and Internet 217 via portal 215 therefrom or An access point (AP) such as access point A 209 and access point B 211 providing access.

Each BSS includes several stations, such as a single AP and station A 219. Within a BSS, an association, such as a wireless IP connection 221, may be formed with one AP at a time. This association rule makes it possible to route or distribute IP data to the station in a defined manner since it knows which AP the station is associated with. Station A has the IP address or destination address of IP A1 223 for the first IP connection, and the message with that address is routed to the station via AP A 209. If station A runs an application on top of SCTP as the transport layer and sets up an additional IP connection or association with a second IP address, IP An 225, the station appears as another station to AP A 209. Can be. If station A 219 and station B 227 want to communicate or exchange information, they may be arbitrarily determined by the IP address IP B1 and station B as the destination address for station B 227 or by using SCTP messages. An IP connection is established between stations A and B using either IP A1 223 or IP An 225 depending on which station A's primary destination address is indicated by station A. Note that the second IP address IP An may have some academic interest but does not have much utilization as long as the availability of station A increases.

A mobile station, such as station A 219, can roam from one BSS to the next BSS and connect to another AP. The 802.11 standards also define an Extended Service Set (ESS) of coordinated BSSs to simplify roaming. This allows for example to allow a customer to roam from a coffee shop to a neighboring bookstore and assume that both settings are still part of the same ESS and continue to browse the Internet. The customer's station either first disconnects or breaks the association with the coffee shop's AP and then associates with the bookstore's AP. This is fast enough to accommodate browser behavior with a few seconds of interruption, but not fast enough for real time or time critical applications such as voice or voice over IP.

FIG. 2 is a first stage for achieving handoff from the first IP connection to the second IP connection for time critical communication as well as serving as a background for the technique of operating 802.11 networks. Station A 219 operating within BSS A 203 first associates IP connection 221 using IP address IP A1 223 with AP A 209. The application of station A, which needs to communicate with the application of station B, communicates via the SCTP transport layer and uses SCTP messages to inform station B that IP A1 is the first destination address before initiating any communications. Thus, communication between the wireless station, station A, and the second station, station B is performed using the first IP connection to the wireless station and the IP address IP A1 and the IP B1 to the other station.

Referring to Fig. 3, the next step in achieving a handoff is discussed and described. FIG. 3 shows what is related to FIG. 2 with similar reference numbers and shows setting up a second IP connection 331 with a second IP address 333 for a mobile or wireless station, station A 219, Wherein the original or first IP connection 221 is the primary connection and is in an "awake" state and is ready to support, provide or continue to provide ongoing communications, and the second IP connection may be a second or You are in a "doze" (low battery consumption) state. Thus both IP connections exist at the same time. Setting up a second IP connection involves searching for an appropriate wireless IP connection, associating it with a second wireless IP access point, such as AP B 211, and notifying the second station of the second IP address 333 using SCTP. Establishing a connection with a second station B. Retrieval, association, and establishment are performed independently of the applications that support communication. The search for an appropriate wireless IP connection is one of the determinations that the available wireless IP connection includes the wireless IP access point and the appropriate services, wireless station A successfully authenticates the access point, and the connection to the second station is available. It may contain the above. Although described as associating with an 802.11 access point, associating with a second wireless IP access point is associated with a Bluetooth access point, hyperlan access point, or other local area network (LAN) access point as now known or later defined. It may be.

More specifically, when wireless station A knows that it is within the coverage of another BSS, such as BSS B 205 (in a known 802.11 specification manner), and expects to switch, wireless station A has an AP B 211 of another BSS. Use at least a second of those IP connections 331 to associate with. Station A continues to use first IP connection 221 to communicate with AP A 209 of original BSS A 203. The first IP address IP A1 223 also maintains a first address for SCTP. However, station A uses the SCTP message to instruct another station with SCTP capabilities to add a second IP address IP A2 333 as another destination address.

This will require wireless / mobility software to interact with the SCTP layer. If the second IP address IP A2 is already known to another SCTP endpoint station B, station A must first instruct station B to delete the second IP address as the destination address. If the second IP connection was previously associated with the original AP, AP A 209, station A must first disassociate the second connection from the original AP. For example, if IP A2 is IP An of FIG. 2, these issues arise. More complex and available and therefore more expensive stations can maintain two independent radio IP resources, each with an AP. However, the STA can also share radio IP resources between the APs of the original BSS and the target BSS. The 802.11 connection of the target AP, AP b 211 and the second IP connection is in a "power save" mode, and the first connection with the original AP is the "active" or "power" appropriate for the application. Power save ". If the first connection is " active ", then the second connection can sometimes wake up to listen to the 802.11 beacons of the target BSS, leading in time to communicate with the AP B 211. This will appear in applications as a small RF defect that can be adjusted by vocoders.

If the first connection with the original AP fails for some reason, Station A should take the second IP connection in "active" mode as soon as possible. Without any stimulus from the mobile station, the other station B will switch independently and automatically through the second IP address. Although this case of error is not handled in real time, it provides a more reliable connection than standard 802.11Q. For improved performance, the station A endpoint will use the first or second IP address to instruct another SCTP endpoint station B to add a second IP address. Preferably, a second IP address is used that will establish the appropriate settings of any new routers in the path between the AP, distribution system (s) and stations.

Assuming the first and second IP connections have established a wireless station, station A, at some point it will determine that the second IP connection 331 should be the primary connection. This determination that the second IP connection should be the primary connection is such that the signal from the first wireless IP access point, AP A 209, is weakened, loading levels for the second IP connection are preferred to AP A, and services are disabled. It is desirable to be available over a 2 IP connection, or if a second IP connection is used, the preferred rate may be made by or include one or more of the decisions used. Upon determining that it is time for station A to switch to BSS B or AP B 211, inform station B that the second IP address, IP A2, is to be the first SCTP destination address, and inform the second connection with AP B 211. You will use SCTP messages to put you in "active" mode. Optionally or if required, inform station B that it should delete the first IP address and disassociate first IP connection 221 from AP A 209.

The result is shown in FIG. 4 after the handoff is performed. Station A may inform station B of the new first address, IP A2, via a second connection and wait for confirmation on that connection. Preferably, station A, after connecting to the " active " mode, informs the other endpoint of the new first address via the second connection. Station A preferably times the switchover to start during the idle period in critical or real time voice communications. Station A may wait to unassociate with AP A until it is outside of AP A's coverage area because having more than one connection increases reliability. Station A associates the first IP connection with AP B after the association is released from AP A, and advertises another endpoint that becomes another SCTP destination address. If station A moves between BSSs of the same ESS, the STA can combine the disassociation and association of the first IP connection with a single reassociation step. It should be noted that the above techniques work even if the handoff is between ESSs. In contrast, since the standards for 802.11 become apparent, ESS transition will cause disruption of services without using the principles and concepts described herein.

With reference to FIGS. 5-7, system level diagrams illustrating handoff for communications between two IP connections using a cellular system and another wireless IP access point will be discussed and described. 5 shows a station such as an IP address, an IP address communicating with station B 505 with IP B1 506, a cellular handset with IP A1 504, and the like, via an IP connection 507 shown wirelessly herein. A 503 is shown. This IP connection 507 is made through a cellular system that includes a cellular base station that is part of a radio access network 509 coupled to a wired network such as the Internet 511 via a cellular core 510. In addition, an 802.11 network including a basic service set (BSS) 515 or access point (AP) with coverage area coupled to the Internet 511 via a distribution system 519 and a portal 521 is provided. Are described.

In summary, handoff to or from a cellular system and a wireless IP network includes setting up a first IP connection comprising using an SCTP to inform station B of a first IP address, IP A1. Then, communication using an application operating with SCTP between the wireless station, station A and station B, uses a first IP connection 507 and a first IP address for station A, and a second IP address for station A. Set up a second IP connection, the first IP connection is the primary connection and the second IP connection is the secondary connection, and both exist at the same time. Determine a second IP connection to be a primary connection; The second IP connection is changed to the primary connection by using SCTP messages to inform the second station that the second IP address is the first address, and the time critical communication is immediately switched over the second IP connection.

Referring to FIG. 5, a wireless station, station A, prior to moving to an 802.11 coverage area is shown. Mobile uses IP over cellular connections. It has at least one IP address (IP A1). The application for Station A, which supports both cellular and wireless IP, will operate in SCTP and will be adjusted to operate in SCTP, or assuming when the station decides to support cellular and wireless IP. Station A informs the other endpoint station B, the IP address associated with the IP connection 507 or the cellular connection, IP A1 504. Station B will use the specific cellular IP address A1 as the first destination address. Station B is connected via the Internet, but may be connected to a cellular core or a cellular radio access network (RAN). Real time applications preferably use a session start protocol to set up a real time or time critical session via SCTP. The use of SIP over SCTP is not enough. In order to work this handoff process, the bearer must also be driven via SCTP. SIP uses Session Description Language (SDL) to indicate how real-time data is transmitted between endpoints. SIP relies on Session Description Protocol (SDP) to provide media negotiation. New extensions can be made to the SDP. Current SDP may indicate that voice or video data uses RTP over UDP. Improvements allow for the specification of operating voice or video over SCTP with the stream of best results. The mobile endpoint, station A, may or may not use additional IP addresses over the cellular connection, and they may or may not provide station B as another SCTP destination address. However, the use of multiple connections over the same cellular connection does not increase much availability.

Referring to Fig. 6, the first IP connection is maintained as the primary connection and the second IP connection is the secondary connection, and both have a second IP address, IP A2 623, for wireless station A, which is present at the same time. The result of setting up the second IP connection 625 is shown. Setting up a second IP connection includes establishing a connection with the second station by searching for an appropriate connection, associating with a wireless IP access point, and notifying the second station of the second IP address using SCTP. . Discovery, association and establishment are performed transparently, independent of application-assisted communications. The search for an appropriate wireless IP connection further includes determining that the available connection includes an access point and appropriate services, and that wireless station A successfully authenticates the access point or that a connection to station B is available. Although described herein in connection with a wireless IP access point that is an 802.11 access point, it is contemplated that other local area access technologies will be desirable from the concepts and principles discussed herein. Informing the station B of the second IP address using SCTP, preferably, the connection is initiated using the second IP connection.

More specifically, preferred 802.11 mobiles, such as station A 503, will regularly scan for proper wireless IP connectivity. When it finds an appropriate connection, it associates it with an access point, authenticates it, and establishes a connection with wired networks. Note that BSS 515 may be associated with a cellular service provider (SP), and wireless station A may use a SIM card for authentication. Alternatively the BSS may not be associated with the SP. There may or may not be a roaming authorization between the operators of the cellular SP and the BSS. Preferably, the present invention works without roaming approval. The mobile can be authenticated independent of BSS and gain access to wired networks. This can be done without any knowledge of the cellular SP. In the case of the above process, the wireless station can obtain a new IP address (eg, via DHCP). The mobile can also use an existing IP address. In any case, the mobile has at least one second IP address, IP A2 623, used over the 802.11 IP connection 625. Mobile or station A then uses the SCTP extension messages to instruct another SCTP endpoint, station B 505, to add a second IP address as an alternative destination address for station A. During this process, the mobile's application continues to use the first IP address over the cellular based IP connection to communicate with station B. While all this is done, the application on station B continues to use the first IP address as the primary address for SCTP, and the application data continues to flow through the cellular system.

Note that the acquisition of the second IP address is not done by the application. The acquisition is done by wireless / mobility software in station A. The wireless / mobility software also interacts with the SCTP layer to inform station B of the second IP address, IP A2 623. If the second IP address has already been associated with the cellular connection, the mobile must first disassociate the second IP address from the cellular connection. In this case, the station B must first be notified of deleting the second address. If the cellular connection fails for some reason, the other endpoint will automatically switch over over the 802.11 connection. The mobile should preferably maintain the 802.11 connection in "active" mode. Although this error is not adjusted in real time, it provides a more reliable connection than prior art approaches. Station A uses the first or second IP address to instruct station B to add a second IP address. Preferably, the second address is used to establish appropriate settings for the AP 517, distribution system 519, and any new routers in the path between the endpoints or stations.

7 shows the results of the following processes in handoff from the cellular to a wireless IP system. Once the second IP connection is set up at some point, wireless station A determines whether the second IP connection is a primary connection. Determining if the second IP connection is the primary connection is desirable for services such as weakening signals from the cellular base station, suitable costs for the second IP connection, and higher bandwidth available over the second IP connection. It may include determining one of the. In any case, station A is now ready to switch over to wireless IP access point 511 and use 802.11. If it is not " active ", station A will cause the second connection with the 802.11 AP 517 to be in " active " mode, using the SCTP extension messages to set the second IP address to the first SCTP purpose. Notify station B that it is an address. The application of station B will begin using the second IP address 623 as the destination address for station A. Given the principles and concepts herein, the switch is somewhat immediate and completely clear for the application.

Similarly, 802.11 APs are for indoor use and cellular coverage may be limited. When station A observes that the quality of the cellular connection is declining, it can inform station B that it should delete the first IP address and stop the cellular IP connection. The application will generally continue to operate. Station A informs station B of the new primary address over the first connection and waits for confirmation of the connection. Preferably, station A, after connecting to the " active " mode, informs station B of the new primary address via the second IP address. Preferably, station A determines the switchover time and starts during an idle or silent period in a time critical communication such as pause or silent during real-time voice switching. Station A may choose to wait to suspend first IP connection 504 until it leaves the coverage area of the cellular system because having one or more connections increases reliability. Station A also associates the first IP connection with the 802.11 AP 517 after disassociating from the cellular system and informs station B that it has become another SCTP destination address.

Roaming into cellular is essentially the inverse of the process described above. The application operates on SCTP using an 802.11 connection on the first IP address. Station B uses the first IP address as the primary destination address. If necessary, station A establishes a connection with the cellular system that supports data transfer on the second IP address. The second IP address can be obtained statically or dynamically. Special preparation may be necessary to achieve adequate quality of service, such as establishing a secondary PDP context in UMTS systems. The software of the mobile then uses the SCTP extension messages to inform the SCTP layer of station B about the availability of the second IP address. Station A's software instructs the SCTP layer of the other endpoint to use the second IP address as the first destination address using the SCTP messages. The mobile may terminate the 802.11 IP connection. Before doing so, SCTP messages must be used to instruct the SCTP layer of station B to delete the first IP address.

Referring to FIG. 8, a functional block diagram of a preferred embodiment of a wireless communication unit 800 suitable for use in the systems of FIGS. 2-7 as a wireless station or station A will be discussed and described. The wireless communication unit 800 is arranged and configured to achieve handoff from a first Internet Protocol (IP) connection to a second IP connection for time critical communication. A wireless communication unit coupled to a known antenna 801 is a conventional wireless transceiver 803 cooperatively arranged to communicate with a second station using a first IP connection and a first IP address for the wireless communication unit and Controller 805. The controller is also coupled to a conventional user input output 807 including, for example, a display, keyboard, or audio transducers, and is a process of setting up a second IP connection with a second IP address for a wireless communication unit, The first IP connection is the primary connection and the second IP connection is the secondary connection, and both perform the setup process which exists at the same time; Determine that the second IP connection should be the primary connection; Change the second IP connection to the primary by using stream control transport protocol (SCTP) messages to inform the second station that the second IP address is the primary address, where the time critical communication is directed to the second IP connection. Switch over immediately.

To do this, the wireless transceiver 803 will require a wireless IP transceiver 808 and may require an additional cellular or local area network transceiver 809. The controller 805 is a processor 811, preferably a known and widely available microprocessor, coupled to an optional port 813 that provides an interface to one or more devices such as a portable computer, PDA, network interface card, modem, or the like. And a digital signal processor, wherein the one or more devices are integrated into a wireless communication unit. The processor is coupled inside memory 815, which is a RAM, ROM, PROM, used to store data and parameters for the routines and instructions as well as software routines or instructions appropriate for a particular unit. Some combination of an EEPROM or other electronic or magnetic storage medium, and a unit that causes a wireless communication unit to operate when required to support handoff processes as disclosed herein, as well as various known functions when executed by the processor It includes. These software instructions or routines coordinate various duties associated with roaming or moving from one access point to another, including communication with other stations or hosts and running on top of the SCTP transport layer, and handoff procedures. One or more applications 817 via IP telephony, an email client or a browser that supports mobility management routines 819, for example voice. It further includes basic and known operating system 821, data and parameter information 823, and many other routines 825 that are known and familiar to those skilled in the art.

A wireless communication unit for achieving IP connectivity over a local area wireless IP network, such as an 802.11 network, or IP connectivity and handoff over a cellular base station, may include a wireless transceiver that includes a cellular transceiver capable of operating in cellular systems. (803). If a handoff is made from one wireless IP network to another, the wireless transceiver requires only wireless IP transceiver 808 as the networks, such as Bluetooth, and sets up and allows one transceiver to maintain multiple IP connections. It is composed. In other embodiments, a second technology dependent transceiver may be required when operating between an 802.11 wireless IP network and a Bluetooth based network, for example. As described above, the wireless communication unit communicates with its destination IP addresses, establishes the appropriate priorities of the IP address, IP connects with other endpoints or stations, whereby the similar syncs described above and As will be appropriately judged based on circumstances, it will operate in accordance with SCTP conventions independent of applications to achieve handoff of communication in a virtual real-time manner between IP connections.

When concluded with reference to FIG. 9, a flowchart of a preferred method of achieving handoff of time critical communications between two IP connections will be discussed and described. The discussion is a summary and eventually a summary step. The method may be preferably executed by the wireless communication unit of FIG. 8 operating in a suitable system as shown in FIGS. 9 illustrates a method of achieving a handoff from a first Internet Protocol (IP) connection to a second IP connection for time critical communication, and using SCTP messages to obtain a first destination IP address for the wireless station. 2 Start at 903 by setting up the first IP connection by notifying the station. By SCTP conventions this is the primary IP address and will eventually be an IP connection between the two stations. At 905 the method then wirelessly via a cellular base station or a wireless IP access point such as an 802.11 access point using a first IP connection and a first IP address for the wireless station supported by the application operating on the SCTP transport layer. The communication between the station and the second station is shown.

At 907, the method illustrates setting up a second IP connection with a second IP address for the first wireless station, where the first IP connection is a primary connection and the second IP connection is a second connection and both Exist at the same time. Setting up the second connection in more detail involves searching for an appropriate connection 909, associating it with a second access point 911, such as a wireless IP access point, and using a SCTP message to associate the second IP address to the second station. Establishing a connection with the second station as a notification. 909, 911 and 913 are preferably done independently of the application supporting the communication. Search 909 for the appropriate wireless IP connection includes that the available connection includes the access point and appropriate services, that the first wireless station can successfully authenticate and access the access point, and that the connection to the second station is used. And determining one of the possible. Association with a wireless IP access point includes associating with one of an 802.11 access point, a Bluetooth access point, a hyperlan access point, and a local area network (LAN) access point in accordance with the provision of each of said access points.

915 then indicates that the signal is weak from the cellular base station or wireless IP access point, the charges for the second IP connection are appropriate, and services such as bandwidth or security available over the second IP connection are desirable. Based on determining one of the two, it is shown that the second IP connection should be the primary connection. Next 917 illustrates changing the second IP connection to the primary connection by using the SCTP messages to inform the second station that the second IP address is the primary address. This immediately switches over the time critical communication to the second IP connection. The 919 then instructs the second station to delete the first IP address using SCTP messages when the second IP connection becomes the primary connection, and sends any information via the cellular base station or to the first wireless IP access point. Terminating the first IP connection by terminating the session.

The apparatus and methods discussed and described above, and the principles and concepts of the present invention, will eliminate the problems caused by lack of consideration of the mobility of prior art wireless IP systems. Using these principles of establishing a second IP connection using SCTP commands and messages that exist concurrently with the first IP connection between stations using the SCTP transport layers, the communication device is time critical at the will of the communication device. Achieve a handoff of the communications to facilitate connection to the respective mobiles. For example, these principles and concepts can be used to achieve handoffs between appropriate cellular packet data systems that do not support fast handoffs such as UMTS and CDMA systems, as well as techniques apparent to those skilled in the art. .

This disclosure is intended to explain how to adapt and use various embodiments in accordance with the invention rather than limiting its true scope and spirit. The description is not intended to be exhaustive or to limit the invention in accordance with the precise forms disclosed. Modifications or variations are possible due to the above teachings. The embodiment (s) are chosen and described in order to best illustrate the principles and embodiments of the invention, and enable those skilled in the art to use the invention in various embodiments and various modifications as are suited to the particular application devised. All modifications and variations are within the scope of the invention as determined by the appended claims, which may be amended during the pending of these applications for patents and all equivalents when interpreted according to the extent to which they are trusted, legal and fair. have.

Claims (42)

A method for achieving handoff from a first Internet Protocol (IP) connection to a second IP connection for time critical communication, the method comprising: Communicating between the first wireless station and a second station using a first IP address for the first wireless station and the first IP connection; Setting up the second IP connection between the first wireless station and the second station with a second IP address for the first wireless station, wherein the first IP connection is a primary connection and a second one; The setup step, wherein the IP connection is a secondary connection, and wherein the first and second IP connections exist simultaneously; Determining a second IP connection to be the primary connection; And Changing the second IP connection to the primary connection by using stream control transport protocol (SCTP) messages to inform the second station that the second IP address is the primary address, wherein the SCTP messages are The modifying step, originating from the first wireless station, And the time critical communication immediately switches over to the second IP connection. 2. The method of claim 1, wherein said step of communicating between said first wireless station and said second station using said first IP connection also uses a cellular base station, said communication operating in SCTP. A method for achieving handoff, supported by the station's application. 3. The method of claim 2, further comprising informing the second station of the first IP address using SCTP before initiating the communication. 3. The method of claim 2, wherein setting up the second IP connection comprises: searching for an appropriate connection, associating with a wireless IP access point, and notifying the second station of the second IP address using SCTP. Establishing a connection with the second station. 5. The method of claim 4, wherein said searching step, said associating step and said establishing step are performed independently of said application supporting said communication. 5. The method of claim 4, wherein retrieving the appropriate wireless IP connection comprises: that the available connection includes an access point and appropriate services, that the first wireless station can successfully authenticate with the access point, and And determining that the connection to the second station is available. 5. The method of claim 4, wherein associating with a wireless IP access point comprises associating with one of an 802.11 access point, a Bluetooth access point, a HyperLAN access point, and a local area network (LAN) access point. The method further comprises a handoff. 5. The method of claim 4, wherein informing the second station of the second IP address using SCTP uses the second connection and thereby initiates the second connection. 3. The method of claim 2, wherein determining that the second IP connection is a primary connection further includes: weakening of a signal from the cellular base station, suiting costs for the second IP connection, and Determining one of the services available over an IP connection is desirable. 3. The method of claim 2, further comprising suspending the first IP connection when the second IP connection becomes the primary connection. 11. The method of claim 10, wherein suspending the first IP connection comprises: instructing the second station to delete the first IP address using SCTP messages, and any session through the cellular base station. Terminating the handoff. 2. The method of claim 1, wherein the step of communicating between the first wireless station and the second station using the first IP connection further uses a first wireless IP access point, the communication operating in a SCTP. A method of achieving handoff, supported by an application of a wireless station. 13. The method of claim 12, further comprising informing the second station of a first IP address using SCTP before beginning the communication step. 13. The method of claim 12, wherein setting up the second IP connection comprises: searching for a suitable wireless IP connection, associating with a second wireless IP access point, and using SCTP to associate the second IP address with the second IP address. Establishing a connection with the second station by notifying the second station. 15. The method of claim 14, wherein said retrieving step, said associating step, and said establishing step are performed independently of said application supporting said communication. 15. The method of claim 14, wherein retrieving the appropriate wireless IP connection is that the available wireless IP connection includes a wireless IP access point and appropriate services, and wherein the first wireless station can successfully authenticate with the access point. And determining one of the presence and the connection to the second station is available. 15. The method of claim 14, wherein associating with the second wireless IP access point further comprises associating with one of an 802.11 access point, a Bluetooth access point, a hyperlan access point, and a local area network (LAN) access point. Including handoff. 15. The method of claim 14, wherein informing the second station of the second IP address using SCTP uses the second connection and thereby initiates the second connection. 13. The method of claim 12, wherein determining the second IP connection to be the primary connection further includes weakening of a signal from the first wireless IP access point and loading levels for the second IP connection. And determining that one of the services available over the second IP connection is desirable. 13. The method of claim 12, wherein when the second IP connection becomes the primary connection, instructing the second station to delete the first IP address using SCTP messages and establishing a connection with the first wireless access point. Suspending the first IP connection by releasing. 3. The method of claim 2, wherein setting up the second IP connection comprises: searching for an appropriate cellular connection, establishing a connection with a second cellular base station, and using a SCTP to assign a second IP address to the second. Establishing a connection with the second station by notifying the station. 13. The method of claim 12, wherein setting up the second IP connection comprises: searching for an appropriate cellular connection, establishing a connection with a second cellular base station, and using a SCTP to assign a second IP address to the second. Establishing a connection with the second station by notifying the station. A wireless communication unit arranged and configured to achieve a handoff from a first Internet Protocol (IP) connection to a second IP connection for time critical communication, A wireless transceiver and a controller cooperatively arranged to communicate with a second station using a first IP address and a first IP connection to the wireless communication unit, The controller is: a process of setting up a second IP connection with a second IP address for the wireless communication unit, wherein the first IP connection is a primary connection and a second IP connection is a secondary connection and the first and second Perform a setup process, wherein a connection exists simultaneously and determine that the second IP connection is a primary connection; Change the second IP connection to the primary connection by using stream control transfer protocol (SCTP) messages to inform the second station that the second IP address is the primary address, And the time threshold communication is switched over immediately to a second IP connection. 24. The wireless transceiver of claim 23 wherein the wireless transceiver comprises a cellular transceiver for communicating with the second station using a first IP connection via a cellular base station, the communication being supported by an application executed by the controller and Wherein said application operates in SCTP. 25. The wireless communication unit of claim 24, further comprising informing the second station of a first IP address using SCTP before initiating the communication. 25. The apparatus of claim 24, wherein the transceiver is further configured by setting up a second IP connection and also searching for an appropriate wireless IP connection, associating with a wireless IP access point, and using the SCTP to inform the second station of the second IP address. And a wireless IP transceiver operatively cooperating with the controller for establishing a connection with a second station. 27. The wireless communication unit of claim 26, wherein the search, association, and establishment are done independently of an application supporting the communication. 27. The method of claim 26, wherein retrieving the appropriate wireless IP connection comprises: that the available connection includes an access point and appropriate services, that the first wireless station can successfully authenticate with the access point, and And determining one of the connection to the two stations is available. 27. The method of claim 26, wherein associating with a wireless IP access point further comprises associating with one of an 802.11 access point, a Bluetooth access point, a hyperlan access point, and a local area network (LAN) access point. And a second transceiver, each compatible with 802.11, Bluetooth, HyperLAN, and local area network systems, respectively. 27. The wireless communication unit of claim 26, wherein informing the second station of the second IP address using SCTP uses the second transceiver and the second connection and thereby initiates the second connection. 25. The method of claim 24, wherein determining that the second IP connection is a primary connection comprises: weakening a signal from the cellular base station, suiting costs for a second IP connection, and establishing the second IP connection. Determining one of the services available via the wireless communication unit. 25. The method of claim 24, wherein when the second IP connection becomes a primary connection, the second station is instructed to delete the first IP address using SCTP messages and terminates any session with the cellular base station. 1 further comprising suspending the IP connection. 24. The wireless transceiver of claim 23 wherein the wireless transceiver comprises a wireless IP transceiver for communicating with the second station using a first IP connection via a wireless IP access point, the communication being performed by an application executed by the controller. And the application is operative in SCTP. 34. The wireless communication unit of claim 33, further comprising informing the second station of a first IP address using SCTP prior to initiating the communication. 34. The wireless IP transceiver of claim 33, wherein the wireless IP transceiver is further configured to set up a second IP connection and to retrieve an appropriate wireless IP connection, associate with a second wireless IP access point, and use SCTP to associate the second IP address with the second IP address. And cooperating with the controller to establish a connection with a second station by informing a station. 36. The wireless communication unit of claim 35, wherein the searching, associating and establishing is done independently of the application supporting the communication. 36. The method of claim 35, wherein retrieving the appropriate wireless IP connection comprises: that the available wireless IP connection includes a wireless IP access point and appropriate services, and that the first wireless station can successfully authenticate with the access point. And determining that the connection to the second station is available. 36. The method of claim 35, wherein the association with the second wireless IP access point further comprises associating with one of an 802.11 access point, a Bluetooth access point, a hyperlan access point, and a local area network (LAN) access point, Wherein the transceiver is compatible with one of 802.11, Bluetooth, HyperLAN, and local area network systems, respectively. 36. The wireless communication unit of claim 35, wherein notifying the second station of a second IP address using SCTP initializes the second connection using the second transceiver and the second connection. 34. The method of claim 33, wherein determining that the second IP connection is to be a primary connection further includes: weakening a signal from the first wireless IP access point, and suitable loading levels for the second IP connection; 2 determining one of the services available over the IP connection is desirable. 34. The first IP connection of claim 33, wherein when the second IP connection becomes a primary connection, instructing the second station to delete the first IP address and releasing the connection with the first wireless access point. And stopping the communication. A method for achieving handoff from a first Internet Protocol (IP) connection to a second IP connection for time critical communication, the method comprising: Communicating between a first wireless station and a second station using a first IP address and a first IP connection for a first wireless station via a first wireless access point, wherein the first IP connection is a primary stream. The communication step, which is a Control Transmission Protocol (SCTP) connection; Establishing a second IP connection between the first wireless station and the second station using a second IP address for the first wireless station via a first wireless access point, wherein the second IP connection is 2 Establishing a second SCTP connection, wherein the first and second IP connections exist simultaneously; Associating with a second wireless access point; Setting up a second IP connection to the second IP address for the first wireless station via the second wireless access point, wherein the first and second IP connections are present at the same time; Determining a second IP connection to be a primary connection; And Changing a second IP connection to a primary connection by informing a second station that a second IP address is a primary address using SCTP messages, wherein the SCTP messages originate from the first wireless station; Including steps And the time critical communication is switched over to a second IP connection.

Images