CN1951128B - System and method for implementing media independent switching - Google Patents

Abstract

A system for implementing media independent handover in a station of a wireless communication system includes a physical sublayer management entity, a medium access control sublayer management entity, a management information base, and a handover policy function. The handover policy function has the capability to receive measurement and system information from the physical sublayer management entity, the mac sublayer management entity, and the management information base. The handover policy function may independently decide whether to perform a handover.

Description

System and method for implementing media independent switching

technical field

The present invention relates generally to wireless communication systems, and more particularly to a method and system for implementing media independent switching between different wireless network formats.

Background technique

A typical mobile system has two main modes of operation: Idle mode and Connect mode. In standby mode, the station (STA) features include: no user service (in other words, no ongoing call or business); monitoring call channel; available service request channel; available for downlink measurements in the radio environment 100% receivers; background coordinates; and unscheduled access points (APs) and/or technology reselection. In connected mode, the station features include: an active user service (such as an ongoing call); possible handover; limited receiver availability for measurement (because of the user's priority); and full Coordinated scheduled access points and/or technology handovers.

Before entering standby mode (such as at start-up), the station must perform selections to determine the best access point and available technology for the requesting user's service. While in standby mode, the station continuously checks for neighboring access points with different technologies. Based on the determination of a "better" access point, the station is transferred (in other words, "reselected") to the new access point.

When in Connected mode, a handoff based on moving from one AP to another AP offering "better" service, including switching to an AP using a different technology. In an ideal situation, handover can occur without significantly disrupting service to the active user.

One goal is to achieve a seamless handover (in other words, to allow a station the movement). Current technology does not provide for this form of switching.

FIG. 1 is an illustration of an existing cellular mobility model 100 showing a radio resource management (RRM) approach to the mobility issue. A cellular station 102 (eg, a 2nd generation mobile station or a 3rd generation UE) is free to move among a plurality of access points 104 . The access point 104 may include, but is not limited to, a Global System for Mobile Communications (GSM) base station and a Frequency Division Duplex/Code Division Multiple Access (FDD/CDMA) Node B. The access points 104 are connected to each other via a radio network 106 . A Handover Policy Function (HPF) 108 is used to guide the station 102 in the access point 104 when the station 102 moves accordingly. The handover strategy function 108 is centrally configured (eg, in a second-generation base station controller (BSC) or a third-generation radio network controller (RNC)) and connected to a network 110 (eg, a switch or server) .

The handoff strategy function 108 provides coordinates as the station 102 moves to different access points 104 . The station 102 sends measurements to the handover policy function 108, which makes the final decision about the handover and which access point 104 the station 102 should be on.

In this model 100, it produces semi-static frequency assignments to each access point 104, and requires some radio planning. In standby mode, access point selection/reselection decisions for both intra-technology (e.g. between GSM) and inter-technology (e.g. between GSM and FDD/CDMA) , is generated in the station 102 and supported by the system information (from the network 110 ) broadcast by the handover policy function 108 . In connected mode, AP handover decisions are made in the handover policy function 108 and are supported by measurements generated by the station, which are sent to the handover policy function 108 via L3 signaling.

FIG. 2 is an illustration of an existing WLAN mobility model 200, showing a distributed radio resource management approach to the mobility issues. An 802.x station 202 is free to move among a plurality of access points 204, which may include but are not limited to 802.11a and 802.16 access points. The access point 204 communicates with a network 208 (eg, gateway or router) via a wireless network 206 .

In this model 200, it produces dynamic frequency assignments for each access point 204 and no radio planning is required. The only supported form of handover in the mobility model 200 is an inter-technology (eg, inter-802.11a) standby mode handover, where the AP selection/reselection decision is made independently in the station 202 . The other form of switching (standby mode and connected mode with mutual technology) is not supported in the mobility model 200 .

In this distributed RRM approach, the access point 204 can be used anywhere and itself is dynamically managed. There is no central point at which RRM is implemented, and thus there is no component in the architecture that performs handover.

Figure 3 is the mobile system architecture currently used in the form of cellular and wireless local area networks. A general packet radio service (GPRS) (2nd generation) station 300 includes a physical layer 302 , a data link layer 304 and a network layer 306 . The data link layer 304 includes a medium access control (MAC) sublayer 310 and a radio link control (RLC) sublayer 312 . The network layer 306 includes a Global System for Mobile Communications (GSM) Radio Resource (RR) Manager 314 , a Mobility Management (MM) Protocol Manager 316 , and an Internet Protocol (IP)/Integration Manager 318 .

A 3rd Generation Partnership Project (3GPP) station 320 includes a physical layer 322 , a data link layer 324 and a network layer 326 . The data link layer 324 includes a media access control sublayer 330 and a radio link control sublayer 332 . The network layer 326 includes a third generation (3G) radio resource controller 334 , a MMP manager 336 , and an Internet protocol/integration manager 338 .

An 802.xx station 340 includes a physical layer 342 , a data link layer 344 and a network layer 346 . The data link layer 344 includes a media access control sublayer 350 and a logical link (LLC) sublayer 352 . The network layer 346 includes a mobile IP manager 354 and an IP/integration manager 356 .

The radio resource manager/controller (314, 334) manages the transient radio link, handling all information about a radio link. The mobility management protocol manager (316, 336, 354) handles network level issues such as registration and location updates when the station moves with the system (in other words, issues other than the call itself).

Current WLAN systems only provide a limited mobility capability. Intra-technology (e.g., between 802.11) and inter-technology (e.g., between 802.11 and 802.16) user transitions are supported using a "break before make" strategy, which is essential for a typical fully mobile Compared with the switching operation in the traditional system (such as the global system for mobile communication), it has the characteristics of repeated selection operation. This problem limits the growth of WLAN technology, as this method is not sufficient to support real-time time services such as audio and video streaming.

Contents of the invention

The present invention is a solution technology that implements a fully mobile approach for both intra-technology and mutual technology transfer scenarios, and meets the needs of both real-time and non-real-time services. The present invention is a device-agnostic handover policy function that places few restrictions on the physical implementation. The present invention supports the transfer between wireless local area networks, and also supports the transfer between wireless local area networks and wired local area networks, and can be integrated with a typical mobile cellular system (such as the Global System for Mobile Communications) to realize a complete mobile WLAN/cellular solution.

A system for implementing media independent switching in a wireless communication system station, including a physical sub-layer management entity, a media access control sub-layer management entity, a management information base and a handover strategy function. The handover policy function is capable of receiving measurement and system information from the PHY, the MAC-SLM, and the MIB. The handover policy function has the ability to independently decide whether to perform a handover next.

A system for implementing media independent switching in a wireless communication system with a station and an access point. The station includes a physical sub-layer management entity, a MAC sub-layer management entity, and a media independent handover (MIH) layer. The MAC layer communicates with the physical sub-layer management entity and the MAC sub-layer management entity. The access point includes a handover policy function that communicates with the media independent handover layer and determines whether the station should perform handover.

A method for implementing media independent handover in a wireless communication system station begins by providing a handover strategy function. System measurements and information are provided from the station to the switching strategy function. And according to the system measurement and information, it is decided whether to execute the handover.

A method for implementing media independent handover in a wireless communication system starts by providing a media independent handover layer in a station and a handover strategy function in an access point. Station measurements are transmitted from the station to the access point through the MAC layer. The Handover Strategy function determines whether the station should perform a handover. The switching is controlled by information transmitted via the media independent switching layer.

A station for implementing media independent handover in a wireless communication system includes a physical sub-layer management entity, a media access control sub-layer management entity, a management information base, and a handover strategy function. The handover policy function is capable of receiving measurement and system information from the PHY, the MAC-SLM, and the MIB. The handover policy function has the ability to independently decide whether to perform a handover next.

An integrated circuit for implementing media independent switching in a wireless communication system station, including a physical sub-layer management entity, a media access control sub-layer management entity, a management information base, and a handover strategy function. The handover policy function has the ability to receive measurements and system information from the physical sub-layer management entity, the media access control sub-layer management entity, and the MIB, the handover policy function has the ability to independently determine whether to perform a handover next .

Description of drawings

From the following description of a preferred embodiment with an example and in conjunction with accompanying diagrams, a subtle understanding of the invention can be obtained:

Fig. 1 is the icon of existing honeycomb mobile model;

FIG. 2 is an icon of an existing wireless local area network mobility model;

Figure 3 is an icon of the mobile architecture currently used in cellular and WLAN network forms;

FIG. 4 is a diagram of a mobile structure in a wireless local area network consistent with the present invention, and compared with a cellular network form;

Fig. 5 is a kind of mobile model of wireless local area network consistent with the present invention;

Figure 6 shows the construction of a station structure to implement the distributed handover strategy function of the present invention; and

FIG. 7 shows the construction of a station structure to implement the centralized handover strategy function of the present invention.

Detailed ways

Hereinafter, the term "station" includes, but is not limited to, a wireless transmit/receive unit, a user equipment, a fixed or mobile subscriber unit, a pager, or any form of device capable of operating in a wireless environment . Also hereafter, the term "access point" includes but is not limited to a base station, a Node B, a location controller, or any form of interface device in a wireless environment.

Figure 4 is a diagram of a mobile structure in a wireless local area network, and compared with a cellular network form. The GPRS station 300 and the 3rd Generation Partnership Project project station 320 are the same as those described above in connection with FIG. 3 . An 802.xx station 400 includes a physical layer 402 , a data link layer 404 and a network layer 406 . The data link layer 404 includes a media access control sublayer 410 and a logical link sublayer 412 . The network layer 406 includes a media independent switching layer 414 , a mobile Internet protocol manager 416 , and an Internet protocol/integration manager 418 . The point of this discussion is the media independent switching layer 414 and how it operates in a mobile model. The MIH layer 414 implements the same functions as the GSM RRM 314 and the G3 RRC 334 .

FIG. 5 is a wireless local area network mobility model 500 consistent with the present invention, which shows two basic handover strategy function options of distributed and centralized. These choices relate to situations not pre-positioned by the mobile model, in other words, standby mode and connected mode switching with internal technology switching.

An 802.x station 502 is free to move among multiple access points 504, which may include but are not limited to 802.11a and 802.16 access points. The access point 504 communicates with a network 508 (eg, gateway or router) through a radio network 506 .

The model 500 can implement a distributed handover strategy function 510 at the station 502 or a centralized handover strategy function 520 at the network 508 .

In a distributed handover strategy function setting, the STA automatically performs the selection, the reselection and handover decisions, which include standby mode, intrinsic technology selection/reselection, and both forms of connection mode handover.

In a centralized HPF setup, the handover strategy function on the system side assists in the selection and reselection process and generates handover decisions supported by information gathered by the station. The information is communicated from the station to the handover policy function through the signaling mechanism of the present invention (ie, the media independent handover layer). This includes standby mode, intrinsic technology selection/reselection, and connection mode switching forms of both.

FIG. 6 is a block diagram showing a functional structure of a distributed handover policy function platform 600 for implementing the present invention. The station 600 includes a physical sub-layer management entity (ME) 602 and a MAC sub-layer management entity 604 . A handover policy function 606 communicates with the PHY 602 and the MAC LME 604 . A local management information base 608 stores information accessed by the handover strategy function 606 to generate the handover decision. The PHY 602 includes a Physical Layer Convergence Procedure (PLCP) sublayer 610 and a Physical Media Independent (PMD) sublayer 612 . The MAC layer management entity 604 includes a MAC layer 614 .

The station 600 makes reselection and handover decisions independently. The handover policy function 606 receives information and other events (generally referred to as information for making handover decisions) from the MAC-SLM entity 604 and the PHY 602 . The handover policy function 606 processes this information and makes an independent decision whether to implement a handover.

This is a limited handover solution technique and is only an extension of the reselection step that would be available in a typical mobile system. This is an adequate but sub-optimal solution technique, mainly due to the use of a "break then make" strategy. With this strategy, when a station knows its radio link is degraded, it either suspends the current link or the link stops itself before establishing a new link. There is no guarantee of resource availability to complete the handover, and the lack of resources to accommodate the handover may weaken the new AP call. This possibility of call attenuation has adequate resolution techniques for non-real-time services, but not for real-time services like voice communications. Furthermore, this is an underscaled solution for the same reasons, i.e. the performance deteriorates as more stations are added to the system.

FIG. 7 is a block diagram showing a functional structure of a functional station 700 for implementing a centralized handover strategy. The station includes a physical sub-layer management entity 702 and a MAC sub-layer management entity 704 . A MAC layer 706 communicates with the physical sub-layer management entity 702 and the MAC sub-layer management entity 704 . The media independent switching layer 706 communicates with a media independent switching layer 708 on the system side. The media independent switching layer 708 communicates with a system switching policy function 710 . The PHY 702 includes a PHY sublayer 712 and a PMI sublayer 714 . The MAC layer management entity 704 includes a MAC layer 716 .

The media independent switching layer 706 communicates with the system switching policy function 710 through the media independent switching layer 708 . The MEHS layer 706 sends measurements to the system handover policy function 710 , and the system handover policy function 710 sends system information to the media independent handover layer 706 . The reselection and handover decisions are based on the exchange of this information, coordinated between the media independent handover layer 706 and the system handover policy function 710 . Using the media independent switching layer 706, the media independent switching layer 708, and the system switching strategy function 710 is similar to a cellular system type switching.

Reselection and handover decisions are coordinated by the system handover policy function 710 and supported by measurement reports and system signals received through the media independent handover layer 706 , 708 . This is a fast and optimal handover resolution technique because the centralized decision making uses a "make then break" policy and guarantees the availability of resources to complete the handover. This is a solution that works for non-real-time services as well as real-time services, and is easily scalable, providing a fully mobile solution.

In order to support a fully mobile solution technology, a mobile communication protocol (such as mobile management, mobile Internet communication protocol, communication initiation protocol (SIP), etc.) and a resource control communication protocol (such as radio resource control ( RRC) or Media Independent Handover Layer) both. The mobile communication protocol supports functions like discovery, registration, forwarding, termination (or calling), switching at the network level (between two switches), and privacy. The resource control communication protocol supports things like system information, termination (or paging), cell selection/reselection, setup, release, measurement reporting, power control, and handover at the radio level (between two radios). However, support provided at two levels is required to support a fully mobile solution.

On the network side, both the media independent switching layer 708 and the switching policy function 710 can reside in any intermediate entity, such as an access point, a server, a database, or a router. In a preferred embodiment, the MIH layer 708 and the handover policy function 710 are located in an access point or an access point controller. The media independent handover layer 708 acts as a state machine, collects the required information, and sends it to the handover policy function 710 . The handover strategy function 710 generates handover decisions based on the received information.

Although the embodiment of the present invention has been described in the form of a wireless local area network, the principle of the embodiment is also applicable to any type of wireless communication system. The centralized handover strategy functional structure can be extended to support wireless-to-wired interworking schemes, such as handover strategies for connecting a wireless device to a wired system. An example of this would be using an 802.11 enabled laptop, then docking the computer and using a switch to utilize the computer docking station's ethernet connection.

Although the components shown in FIGS. 6 and 7 are described as separate components, these components can also be considered as a single integrated circuit (IC), such as an application-specific integrated circuit (ASIC), multiple integrated circuits, discrete components , or a combination of discrete components and integrated circuits. In certain implementations, the functionality of the embodiments and features of the present invention may reside in discrete components/integrated circuits and may be partially/completely disabled or eliminated.

Although the features and components of the present invention have been described in specific combinations in the preferred embodiment, each feature or component can be used alone (not together with other features and components of the preferred embodiment) or in combination with the present invention Other features of the invention come into different combinations together with the components or individually.

Claims (22)

1. platform that is configured to implement centralized switchover policy function, this platform comprises:

IEEE 802.xx medium access control physical sublayer management;

IEEE 802.xx physics physical sublayer management; And

Media independent handover layer; This media independent handover layer be configured to said platform in medium access control physical sublayer management and physics physical sublayer management communicate, and receive portable protocol information and resource control protocol information from network switchover policy function.

2. platform according to claim 1 is characterized in that, said media independent handover layer also is configured to metrical information is sent to said switchover policy function.

3. platform according to claim 1 is characterized in that, said media independent handover layer also be configured in order to said platform in IEEE 802.xx LLC communicate by letter.

4. platform according to claim 1 is characterized in that, said network switchover policy function is the assembly in the wireless network.

5. platform according to claim 1 is characterized in that, said portable protocol information comprises switching command, and wherein said platform also is configured to carry out the switching from first network to second network in response to said switching command.

6. platform according to claim 5 is characterized in that, said first network is a cellular network, and said second network is an IEEE 802.xx network.

7. platform according to claim 5 is characterized in that, said first network is an IEEE 802.xx network, and said second network is a cellular network.

8. platform according to claim 5 is characterized in that, said first network is an IEEE 802.xx network, and said second network is an IEEE 802.xx network.

9. platform according to claim 8 is characterized in that, said first network is IEEE 802.16 networks, and said second network is IEEE 802.11 networks.

10. platform according to claim 8 is characterized in that, said first network is the IEEE802.11 network, and said second type network is IEEE 802.16 networks.

11. a method of in being arranged to the platform of implementing centralized switchover policy function, using, this method comprises:

Metrical information is sent to network switchover policy function from media independent handover layer, and said media independent handover layer is configured to communicate with IEEE 802.xx medium access control physical sublayer management and IEEE 802.xx physics physical sublayer management;

Media independent handover layer place at said platform receives the switching command from said network switchover policy function; And

Carry out the switching of make-before-break type from first network to second network in response to said switching command.

12. method according to claim 11 is characterized in that, said media independent handover layer is communicated by letter with the IEEE 802.xx LLC in the said platform.

13. method according to claim 11 is characterized in that, said first network is a cellular network, and said second network is an IEEE 802.xx network.

14. method according to claim 11 is characterized in that, said first network is the IEEE802.xx network, and said second network is a cellular network.

15. method according to claim 11 is characterized in that, said first network is an IEEE 802.xx network, and said second network is an IEEE 802.xx network.

16. method according to claim 11 is characterized in that, said first network is IEEE 802.16 networks, and said second network is IEEE 802.11 networks.

17. method according to claim 11 is characterized in that, said first network is IEEE 802.11 networks, and said second network is IEEE 802.16 networks.

18. one kind is arranged to the platform of implementing centralized switchover policy function, this platform comprises:

First communicator is configured to utilize IEEE 802.xx agreement;

The second communication device is configured to utilize second wireless communication protocol; And

Can operate with the processing unit with IEEE 802.xx protocol communication with said first communicator, wherein said IEEE 802.xx agreement is configured to utilize physical layer, medium access control layer and media independent handover layer;

Said processing unit can also be operated to combine said second wireless communication protocol to communicate by letter with second cordless communication network with said second communication device, and wherein said second wireless communication protocol is configured to utilize physical layer, medium access control layer and media independent handover layer;

Wherein said processing unit can also with the media independent handover layer of said IEEE 802.xx agreement and the media independent handover layer binding operation of said second wireless communication protocol stack, to receive portable management information from network switchover policy function.

19. platform according to claim 18 is characterized in that, said processing unit can also be operated to carry out the switching from first wireless network to second wireless network in response to said portable management information.

20. platform according to claim 10 is characterized in that, said first network is the IEEE802.xx network, and said second network is a cellular network.

21. platform according to claim 19 is characterized in that, said first network is the IEEE802.xx network, and said second network is an IEEE 802.xx network.

22. platform according to claim 19 is characterized in that, said first network is the IEEE802.11 network, and said second network is IEEE 802.16 networks.

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