Abstract:
The present invention proposes an infrastructure to enable seamless mobility for wireless metropolitan area networks (WMANs) and to provide for management of spectrum and network resources. An WMAN reference model is introduced where the radio resource management (RRM) and handover (HO) sub-layer is introduced into the protocol stack. The WMAN management plane is responsible for the RRM and HO management. Several physical and logical network architecture options for WMAN management are proposed.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 11/261,336, filed Oct. 28, 2005, now U.S. Pat. No. 7,848,291, issued Dec. 7, 2010, which claims the benefit of U.S. Provisional Patent Application No. 60/625,628, filed Nov. 5, 2004, which is incorporated by reference as if fully set forth herein. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to wireless metropolitan area networks (WMANs), and more particularly, to an architecture for managing network resources and mobility in a WMAN. 
     BACKGROUND 
     Wireless metropolitan area network (WMAN) standards have to define a network structure that provides the network equipment with procedures to enable management of network resources, mobility, and spectrum. This network architecture should allow the networks to perform seamless handover between different WMAN networks and harmonize the handover process with 802.21 for seamless mobility with other wireless networks (e.g., 802.11 wireless local area networks, cellular, etc.). 
     Current solutions do not define how WMAN network resources are managed and how users can handover seamlessly between various WMAN networks or from WMAN networks to different access technologies. There is a need to define reference models and network architectures for radio resource management (RRM) and mobility management between WMAN and heterogeneous access technologies. 
     SUMMARY 
     The present invention proposes an infrastructure to enable seamless mobility for WMAN networks and provide for management of spectrum and network resources. A network reference model is introduced where the radio resource management (RRM) and handover (HO) sublayer is introduced into the protocol stack. The network management plane is responsible for the RRM and HO management. Also, the invention proposes physical and logical network architecture options for network management. 
     A system for managing resources in a WMAN includes a control and data plane and a management plane. The control and data plane includes a service specific convergence sublayer, a MAC common part sublayer (CPS), and a physical sublayer. The management plane includes a service specific convergence sublayer management entity, a MAC CPS management entity, a RRM sublayer, a handover sublayer, a physical sublayer management entity, and a management service access point, through which the components of the management plane communicate with each other. 
     A system for managing handovers in a WMAN includes a mobile IP part; a handover sublayer, the handover sublayer being specific to a network type of the WMAN; a media independent handover (MIH) lower layer convergence function (LLCF), the LLCF being specific to a network type of the WMAN; a MIH handover function; and a MIH higher layer convergence function. 
     A system for managing resources in a WMAN includes a base station, a radio access gateway, a core network, and a MIH access gateway. The base station is configured to communicate with a station. The radio access gateway is configured to operate as a system management entity and to communicate with the base station. The core network communicates with the radio access gateway. The MIH access gateway is configured to perform media independent handovers and to communicate with the radio access gateway. 
     A system for managing resources in a WMAN includes a base station, an access gateway, and a core network. The base station is configured to communicate with a station. The access gateway communicates with the base station and includes a radio access gateway and a MIH access gateway. The MIH access gateway is configured to perform media independent handovers and to communicate with the radio access gateway. The core network communicates with the access gateway. 
     A system for managing resources in a WMAN includes a base station and a core network. The base station includes a MAC and physical layer device, a radio access gateway, and a MIH access gateway. The radio access gateway is configured to communicate with the MAC and physical layer device. The MIH access gateway is configured to perform media independent handovers and to communicate with the radio access gateway. The core network communicates with the base station. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of a WMAN reference model; 
         FIG. 2  is a diagram of an 802.16 g handover management plane; 
         FIG. 3  is a diagram of a first embodiment of a WMAN logical network architecture; 
         FIG. 4  is a diagram of a second embodiment of a WMAN logical network architecture; 
         FIG. 5  is a diagram of a third embodiment of a WMAN logical network architecture; 
         FIG. 6  is a diagram of a first embodiment of a WMAN physical network architecture; 
         FIG. 7  is a diagram of a second embodiment of a WMAN physical network architecture; and 
         FIG. 8  is a diagram of a third embodiment of a WMAN physical network architecture. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereafter, the term “station” (STA) includes, but is not limited to, a wireless transmit/receive unit, a user equipment, a fixed or mobile subscriber unit, a pager, or any other type of device capable of operating in a wireless environment. When referred to hereafter, the term “access point” (AP) includes, but is not limited to, a base station, a Node B, a site controller, or any other type of interfacing device in a wireless environment. 
     The present invention defines a generic architecture for WMAN equipment to allow for seamless mobility within a WMAN. Also, it provides for mobility between heterogeneous networks. Section 1 introduces the protocol reference model. The management plane concept is used to address mobility and network resource management. Section 2 shows the logical network architecture. Two new logical nodes are introduced, the System Management Entity (radio access gateway) and the Media Independent Handover (MIH) access gateway. Section 3 shows how the logical architecture can be mapped to different implementations. 
     1. WMAN Protocol Reference Model 
       FIG. 1  is a diagram of the proposed WMAN reference model  100 . The model  100  includes a control and data plane  102  and a management plane  104 . The control and data plane  102  includes a service specific convergence sublayer (CS)  110 , a medium access control (MAC) common part sublayer (MAC CPS)  112 , a security sublayer  114  (which is part of the MAC CPS  112 ), and a physical sublayer  116 . The management plane  104  includes a service specific CS management entity  120 , a MAC CPS management entity  122 , a security sublayer  124  (which is part of the MAC CPS management entity  122 ), a RRM and HO sublayer  126 , a physical sublayer management entity  128 , and a management service access point (SAP) interface  130 . While the RRM and HO sublayer  126  is shown in  FIG. 1  as a single layer, the RRM and HO sublayer  126  can alternatively be configured as a separate RRM sublayer and an HO sublayer or the HO layer could be a sublayer to the RRM layer. 
     The SAP interface  130  is used to configure the MAC layer and the physical layer, and to obtain measurements from the MAC layer and the physical layer. Additionally, the SAP interface  130  connects the RRM and HO sublayer  126  to RRM and handover functionalities, which contain RRM and handover decision-making processes. The RRM and handover functionalities are located outside the MAC management entity  122 . These functionalities include the algorithms that receive inputs from the MAC management entity  122  and make RRM and handover decisions. These functionalities can be located in the SME (session management entity) in the  802  reference model. 
       FIG. 2  is a diagram of an 802.16 g-handover management plane  200 . The management plane  200  includes a mobile IP part  202 , an 802.16 HO sublayer  204 , an 802.21 MIH dot16 lower layer convergence function (LLCF)  206 , an MIH HO function  208 , and an MIH mobile IP higher layer convergence function (HLCF)  210 . A SAP to MAC interface  220  and a SAP to PHY interface  222  are used to connect the 802.16 HO sublayer  204  to the 802.21 MIH management plane. 
     Handover inside 802.16 networks is the responsibility of the 802.16 HO sublayer  204 . The HO sublayer  204  configures the 802.16 MAC and physical layers to send measurements and handover triggers via the MAC and physical SAPs  220 ,  222 , respectively. If there is a need to change the 802.16 subnet, the 802.16 HO sublayer  204  sends the triggers to the mobile IP part  202 . For an inter-technology handover (e.g., 802.16 to cellular or 802.16 to 802.11), handover triggers are sent from the 802.16 HO sublayer  204  to the 802.21 MIH dot16LLCF  206 . The 802.21 MIH handles the handover scenarios if there is a need to change the domain or performing a handover with other technologies. 
     While the management plane  200  is described in connection with an 802.16 network, the management plane can be implemented in any type of WMAN by changing the HO sublayer  204  and the LLCF  206  to correspond to the appropriate network type. 
     2. WMAN Logical Network Architecture 
       FIGS. 3-5  present different WMAN logical network architectures, in which the physical and MAC layers are located inside the base station (BS). The HO sublayer is located in the system management entity, namely the radio access gateway. This system management entity can be responsible for one or more BSs in the same subnet. The MIH access gateway contains the 802.21 MIH functionality. The BS communicates with the mobile station subscriber via the U interface and communicates with another BS via the IB interface. The radio access network (RAN) is connected to the IP core network via the I-CN interface. 
       FIG. 3  shows a first embodiment of a logical architecture  300 , where all logical nodes are connected via standardized logical interfaces. The architecture  300  includes a plurality of wireless stations  302 , a RAN  304 , an IP core network  306 , and an MIH access gateway  308 . The RAN  304  includes one or more base stations (BS)  310  and at least one radio access gateway  312 , which is a system management entity. 
     A wireless station  302  communicates with a BS  310  over the U interface  320 . The BSs  310  communicate with each other over the IB interface  322 . The BSs  310  communicate with the radio access gateways  312  over the A interface  324 ; this is a reuse of the standardized A interface between the BS and the Authentication and Service Authorization server (ASA). The radio access gateways  312  communicate with each other over the AG interface  326 . The radio access gateway  312  communicates with the IP core network  306  over the I-CN interface  328 . The radio access gateway  312  communicates with the MIH access gateway  308  over the I-CMIH interface  330 . 
       FIG. 4  shows a second embodiment of a logical network architecture  400 . The architecture  400  includes a plurality of wireless stations  402 , a RAN  404 , an IP core network  406 , and an MIH access gateway  408 . The RAN  404  includes one or more BSs  410  and at least one radio access gateway  412 , which is a system management entity. 
     A wireless station  402  communicates with a BS  410  over the U interface  420 . The BSs  410  communicate with each other over the IB interface  422 . The BSs  410  communicate with the radio access gateways  412  over the A interface  424 . The radio access gateway  412  communicates with the IP core network  406  over the I-CN interface  426 . The radio access gateway  412  communicates with the MIH access gateway  408  over the SAP interface  428 . The IP core network  406  communicates with the MIH access gateway  408  over the I-CN′ interface  430 . 
     A third embodiment of a logical architecture  500  is shown in  FIG. 5 . The architecture  500  includes a plurality of wireless stations  502 , a RAN  504 , an IP core network  506 , and an MIH access gateway  508 . The RAN  504  includes one or more BSs  510  and at least one radio access gateway  512 , which is a system management entity. 
     A wireless station  502  communicates with a BS  510  over the U interface  520 . The BSs  510  communicate with each other over the IB interface  522 . The BSs  510  communicate with the radio access gateways  512  over the SAP interface  524 . The radio access gateway  512  communicates with the IP core network  506  over the I-CN interface  526 . The radio access gateway  512  communicates with the MIH access gateway  508  over the SAP interface  528 . The IP core network  506  communicates with the MIH access gateway  508  over the I-CN′ interface  530 . 
     The main difference in the architecture  500  is that the radio access gateway  512  is connected to the MIH access gateway  508  via a SAP interface ( 528 ), but it is also connected to the BS  510  via another SAP interface ( 524 ). 
     3. WMAN Physical Network Architecture 
     The three logical network architecture options  300 ,  400 ,  500  allow WMAN equipment manufacturers to map these architecture options into different physical network implementations, for example as shown in  FIGS. 6-8 . 
       FIG. 6  is a diagram of a first embodiment of a physical network architecture  600 . The architecture  600  includes a plurality of wireless stations  602 , a RAN  604 , an IP core network  606 , and an MIH access gateway  608 . The RAN  604  includes one or more BSs  610  and at least one radio access gateway  612 , which is a system management entity. 
     A wireless station  602  communicates with a BS  610  over the U interface  620 . The BSs  610  communicate with each other over the IB interface  622 . The BSs  610  communicate with the radio access gateways  612  over the A interface  624 . The radio access gateways  612  communicate with each other over the AG interface  626 . The radio access gateways  612  communicate with the IP core network  606  over the I-CN interface  628 . The radio access gateways  612  communicate with the MIH access gateway  608  over the I-CMIH interface  630 . The IP core network  606  communicates with the MIH access gateway  608  over the I-CN′ interface  632 . 
     The architecture  600  includes three major physical nodes on the network side: the BS  610 , which can contain only the physical layer and possibly the MAC layer; the radio access gateway  612 , which contains the handover functionalities; and the MIH access gateway  608 , which contains all the MIH functionalities (i.e., 802.21). The architecture  600  assumes the use of centralized handover management entities. 
       FIG. 7  is a diagram of a second embodiment of a physical network architecture  700 . The architecture  700  includes a plurality of wireless stations  702 , a RAN  704 , and an IP core network  706 . The RAN  704  includes one or more BSs  710  and at least one access gateway  712 . Each access gateway  712  includes a radio access gateway  714  and an MIH access gateway  716 . 
     A wireless station  702  communicates with a BS  710  over the U interface  720 . The BSs  710  communicate with each other over the IB interface  722 . The BSs  710  communicate with the access gateways  712  over the A interface  724 . The radio access gateway  714  and the MIH access gateway  716  communicate with each other over a SAP interface  726 . The access gateways  712  communicate with each other over the AG interface  728 . The access gateways  712  communicate with the IP core network  706  over the I-CN interface  730 . 
     The architecture  700  is an alternative implementation for the centralized solution, where all the handover functionalities (radio network and 802.21 handover) are centralized in the access gateway  712 . The radio network and 802.21 handover functionalities interface with each other via the SAP interface  726  in the access gateway  712 . In the architecture  700 , the BS  710  contains only the physical and MAC layers. 
       FIG. 8  is a diagram of a third embodiment of a physical network architecture  800 . The architecture  800  includes a plurality of wireless stations  802 , a RAN  804 , and an IP core network  806 . The RAN  804  includes one or more BSs  810 . Each BS  810  includes a MAC and PHY section  812 , a radio access gateway  814 , and an MIH access gateway  816 . 
     A wireless station  802  communicates with a BS  810  over the U interface  820 . The MAC and PHY section  812  communicates with the radio access gateway  814  over a first SAP interface  822 . The radio access gateway  814  and the MIH access gateway  816  communicate with each other over a second SAP interface  824 . The BSs  810  communicate with each other over the IB interface  826 . The BSs  810  communicate with the IP core network  806  over the I-CN interface  828 . 
     The architecture  800  includes a “fat” BS  810 , where the radio network and 802.21 handover functionalities are implemented in the BS. The handover functionalities communicate with each other and with the Physical and MAC layers via the first and second SAPs  822 ,  824 . 
     While the present invention has been described in connection with a WMAN and some examples have been provided relating to an 802.16-based network, the principles of the present invention (in particular, the management plane procedures and services and the media independent handover functionality) are applicable to any type of wireless network. 
     Although the features and elements of the present invention are described in the preferred embodiments in particular combinations, each feature or element can be used alone (without the other features and elements of the preferred embodiments) or in various combinations with or without other features and elements of the present invention. While the present invention has been described in terms of preferred embodiments, other variations which are within the scope of the invention as outlined in the claims below will be apparent to those skilled in the art.