BACKGROUND OF THE INVENTION
This application claims the benefit under 35 U.S.C. §119(e) of U.S. Patent Application No. 60/687,833 filed Jun. 6, 2005, for “MOBILE AND WIRELESS NEIGHBORHOOD DISCOVERY USING DHCP”, which is hereby incorporated by reference.
1. Field of the Invention
This invention relates to wireless networks, and particularly to configuration and capability discovery in Internet Protocol (IP) based wireless networks.
2. Description of Related Technology
Recently a variety of computer network systems have been widely used. Such network systems include a local area network (LAN), a wide area network (WAN), a metropolitan area network (MAN), a wireless local area network (WLAN), a wireless personal area network (WPAN), a general packet radio service (GPRS) network and other wireless network systems, such as wireless fidelity (WiFi), worldwide interoperability for microwave access (WiMAX) and code division multiple access 2000 (CDMA2000). WiFi is a term for certain types of WLANs that use specifications in the IEEE 802.11 family. WiMAX is a form of broadband wireless access based on the IEEE 802.16 standard for MANs. CDMA is also known as IMT-CDMA Multi Carrier or 1ŚRTT, and is a third generation mobile wireless technology. The network systems allow communication between various end terminals or mobile stations such as a personal computer (desktop, laptop, palmtop or handheld), a mobile phone, or other portable communication devices. It is typical that the above network systems include at least one bridge element such as an access node or access point where user traffic enters and exits a communications network.
Dynamic Host Configuration Protocol (DHCP)   allows a host (a computing device such as an end terminal or a mobile station) to discover the capabilities and configurations associated with a currently serving access network. The DHCP, however, does not provide this information for any of the other networks (target networks) that the host may connect to. Neighbor networks are wireless networks in the vicinity or neighborhood of a mobile station.
There is some ongoing work to achieve this goal over Media Access Control (MAC) layer designs . Such designs can provide only a subset of the information that is needed for a full discovery. In addition, as Level 2-specific (of the seven layer open system interconnection model) mechanisms, they lack universal applicability (for example, an IEEE 802.11k solution works only on IEEE 802.11 links, and on nothing else). Such designs also cannot be easily applied to legacy networks that are already deployed.
A very small subset of the target information is incorporated in some specific protocol work, such as Proxy Router Discovery used in Mobile IPv6 Fast Handovers  (e.g., prefix information of the candidate access router). Again, this has very limited applicability and cannot solve the general problem.
Current solutions lack the fundamental needs of wireless networks:
Applicability to any IP networks (All-IP)
Discovering the presence of neighbor networks
- SUMMARY OF CERTAIN INVENTIVE ASPECTS OF THE INVENTION
Learning the extensive list of capability and configurations of neighbor networks.
Embodiments of a method and system for proactively discovering a capability and configuration of candidate wireless networks in the neighborhood of a mobile station are described. The DHCP enables a mobile station to discover the capabilities and configurations of a currently serving network. Using the method, the mobile station can discover the wireless networks in its vicinity and the respective capability and configurations. This enables the mobile station to make better handover decisions in selecting target networks, take preparatory actions prior to the handover, and expedite the connection setup once the mobile station connects to the target.
In one embodiment, there is a network having a dynamic host configuration protocol server, comprising a dynamic host configuration protocol (DHCP) server embedded in a network being in a neighborhood of identified wireless networks; a database, in data communication with the DHCP server, configured to store at least media access control (MAC) address of each identified network; and an access point, in communication with the DHCP server, configured to send beacons to at least one mobile station, wherein each beacon has at least a MAC address of the access point; wherein the DHCP server receives a request for configuration and capability information of one or more of the identified networks, obtains the requested information from the database, and provides the requested information to a mobile station that requested the information.
In another embodiment, there is a network discovery method, comprising maintaining a database of network identifiers associated with a plurality of networks in a neighborhood of a particular network, sending beacons from an access point of at least one network identified in the database, receiving a request for capability and/or configuration information of at least one network identified in the database, and providing the requested capability and/or configuration information to a mobile station.
In another embodiment, there is a network discovery system, comprising means for storing information about identified networks in a neighborhood of a particular network, means for sending beacons from an access point of at least one network identified in the storing means,
means for receiving a request for capability and/or configuration information of at least one network identified in the storing means, and means for providing the requested capability and/or configuration information to a mobile station.
In another embodiment, there is a network discovery method, comprising storing information about a plurality of networks in a neighborhood of a particular network, sending beacons from an access point of at least one of the neighborhood networks, requesting capability and configuration information of at least one network, and providing the requested capability and configuration information to a mobile station.
In another embodiment, there is a network discovery method, comprising learning information about one or more access networks within a neighborhood of a mobile host via dynamic host configuration protocol (DHCP).
BRIEF DESCRIPTION OF THE DRAWINGS
In yet another embodiment, there is a network discovery method, comprising learning a configuration and capability of a given access network via dynamic host configuration protocol (DHCP) by a mobile station.
The foregoing and other features of the invention will become more fully apparent from the following description and appended claims taken in conjunction with the following drawings, in which like reference numerals indicate identical or functionally similar elements.
FIG. 1 is a diagram illustrating an exemplary configuration of components and related operations of an embodiment of the invention.
FIG. 2 is a flowchart of an exemplary process operating on the configuration shown in FIG. 1.
FIG. 3 is a diagram of an exemplary DHCP request option format as used by the process of FIG. 2.
DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS OF THE INVENTION
FIG. 4 is a diagram of an exemplary DHCP reply option format as used by the process of FIG. 2.
FIG. 1 illustrates an exemplary configuration of an embodiment of a wireless network system 100 that proactively discovers a capability and configuration of candidate wireless networks in the neighborhood of an exemplary mobile station (MS) 130. The network system 100 may be implemented with one or more of an IEEE 802.11 a/11b/11g (WiFi) network, a wireless local area network (WLAN), a metropolitan area network (MAN) (e.g., WiMAX), a wireless personal area network (WPAN), a general packet radio service (GPRS) network, a global system for mobile communication (GSM) network, a code division multiple access (CDMA) network (e.g., CDMA200), a Bluetooth network or other wireless networks. As shown in FIG. 1, the system 100 includes a plurality of networks operated by multiple network operators. These networks include a WiFi network 110 operated by Operator A, a CDMA2000 network 140 operated by Operator A, WiFi network 150 operated by Operator B, a WiMAX network operated by Operator A, and a CDMA2000 network operated by Operator C. In the exemplary configuration of FIG. 1, WiFi network 110 includes a first access point (AP1) 112, a second access point (AP2) 114, and a DHCP server 116 for performing the DHCP. The DHCP server 116 is connected to a neighborhood database 120, which will be further described below. CDMA2000 network 140 includes a first base station (BS1) 142. WiFi network 150 includes a third access point (AP3) 152 and a fourth access point (AP4) 154. WiMAX network 160 includes a second base station (BS2) 162 and a third base station (BS3) 164. CDMA2000 network 170 includes a fourth base station (BS4) 172 and a fifth base station (BS5) 174. The DHCP server 116 may be hosted by an access point, an access router, or a dedicated server of an access network, for example. In other embodiments, some or all of the other networks 140, 150, 160 and 170 also have their own DHCP server, similar to DHCP server 116.
The exemplary mobile station 130, e.g., a mobile telephone, is in communication with the network 110 as shown by paths 180, 181 and 184 of FIG. 1. The DHCP server 116 is in data communication with the neighborhood database 120 as shown by paths 182 and 183. This communication will be further described in conjunction with FIG. 2 below.
In one embodiment, the neighborhood database 120 includes a plurality of fields for each access point or base station in the networks of the system 100. These fields include a media access control (MAC) address, an operator identifier, a network access server (NAS) identifier, and an Internet protocol identifier (e.g., IPv4, IPv6). Naturally, in other embodiments, the database 120 can contain other fields.
In a wireless network, an access point is generally a station that transmits and receives data to connect users to other users within the network and also can serve as the point of interconnection between the wireless network and a fixed wire network. In a WiFi network embodiment, an example of one or more of the access points 112, 114, 152 and 154 can be an Airespace 1200, available from Airespace Inc., an IronPoint, available from Foundry Networks, or an Altitude 300, available from Extreme Networks.
The mobile station 130 can be referred to as an end terminal or a user device. The mobile station 130 can include, for example, a personal computer (laptop, palm-top), a mobile phone, or other portable communication devices such as a hand-held PC, a wallet PC and a personal digital assistant (PDA).
Referring to FIG. 2
(in conjunction with FIG. 1
), a flowchart of an exemplary process 200
for operating on the exemplary configuration 100
shown in FIG. 1
will be described. Process 200
begins at a start state 202
and proceeds to state 204
where the DHCP server 116
of the current network 110
maintains the database 120
of other networks in its neighborhood. In certain embodiments, the database 120
can be created and updated manually. The neighborhood coverage of the database 120
depends on local policy. For example, the list can contain:
- All networks from the same operator
- The list may be compartmentalized based on geographic locations (e.g., all WiFi APs in the San Francisco Bay area)
- Or, all networks within the same IP subnet of the operator;
- All networks of the operators that are affiliated or have roaming agreements.
Proceeding to state 206, the MS hears or receives periodic beacons from one or more networks in the system, such as from the access points or base stations of the networks. For the sake of simplicity, an access point is to be considered as including both access points and base stations. In certain embodiments, beacon frames are described as part of the IEEE 802.11 wireless network protocol. Each beacon transmission identifies the presence of an access point and includes information regarding the access point for the mobile stations that are within range. The beacon interval is a variable parameter. For example, path 180 shown in FIG. 1 represents a beacon from AP1 112. Advancing to state 208, in certain embodiments, the mobile station (MS) identifies the neighbor networks by their MAC addresses, such as the base station identifier (BSSID) used by IEEE 802.11 access points. The MAC addresses are readily available (e.g., they are used in beacons) once the MS is within the network coverage region. In one embodiment, this identifier is the best one suited for rapid recognition.
At any given time, but shown as state 210
of process 200
, the MS can either request:
- Detailed capability/configuration information on all possible networks in its neighborhood (e.g., get all), or
- Detailed capability/configuration information on a selected target network (e.g., get one)
- It is assumed that the MS has already identified the MAC address of the target network (e.g., by hearing periodic beacons).
The MS can do one of the previous requests depending on usage. For example, if the MS knows it is only interested in one target network, it can “get one”, but if the MS has not decided yet, it may “get all” and make a decision based on the information it gets. For example, the mobile station requests detailed information via path 181 to the DHCP server 116 as shown in FIG. 1. In certain embodiments, the MS requests information about more than one target network. The DHCP server provides both configuration and capability information. For example, a MS can configure an IP address by getting one from the DHCP server, or learn that there is a “Mobile IP home agent” capability in the access network by learning the IP address of one.
Continuing at state 212, the DHCP server in the currently serving network responds to the MS request by requesting data from the neighborhood database 120. For example, this request is sent via path 182 to the database 120 as shown in FIG. 1. Moving to state 214, the database 120 provides the requested data about the neighbor networks or target network to the DHCP server 116. For example, the database 120 sends the requested information via path 183 to the server 116 as shown in FIG. 1. Advancing to state 216, the DHCP server responds to the MS through the access point (or base station, depending on the particular network) with the requested information. For example, the server 116 sends the requested information via path 184 to the MS 130 as shown in FIG. 1. Proceeding to optional state 218, the MS connects to a selected network based on the response from the DHCP server. In certain embodiments, the MS includes a network selection mechanism to select the network. In another embodiment, the MS displays the requested information about the neighbor networks or target networks, and a user selects one of the networks. Process 200 completes at an end state 220.
Referring to FIG. 3, the protocol details for an exemplary DHCP request option 300 will be described. This request option 300 can be the request made by the MS in state 210 of process 200 (FIG. 2) and sent across path 181 (FIG. 1). The request option 300 includes a neighborhood request 310 and an option length 312. The neighborhood request 310 indicates the type of DHCP request and the option length 312 is the size (in Bytes) of the option, and both are compliant with the standard DHCP option formats as specified in the DHCP references. A target MAC address(es) section 320 is optionally included. If one or more specific targets are not provided, the information of all neighbors is requested. The section 320 includes a MAC type portion and a target network MAC address portion. The MAC type determines the length and format of the MAC address.
Referring to FIG. 4, the protocol details for an exemplary DHCP reply option 400 will be described. This reply option 400 can be the reply sent to the MS in state 216 of process 200 (FIG. 2) via path 184 (FIG. 1). The reply option 400 includes a neighborhood request 410 and an option length 412. In this example, information sets are provided for two networks, which is associated with the situation when two target networks are specified in the request or there are only two networks in the system. An information set 420 for network 1 and an information set 430 for network 2 are shown. Each information set includes an information length portion and multiple information portions or fields, e.g., five information fields in one embodiment. Each information field has an information type portion 432, a length portion 434 and a value portion 436. The information fields are populated with data from the neighborhood database 120 (FIG. 1).
Each access point in the neighborhood is entered as a separate “access network” in the neighborhood database 120 (FIG. 1). In reality, from a management or configuration perspective, multiple access points may be part of the same “administrated network,” but from a discovery point of view, this does not matter. In certain embodiments, for performance optimizations, some aggregation can be used in order to prevent repeating the same information for multiple elements of the database.
The database 120 may contain both static and dynamic (e.g., network load) information. While static information can be entered manually, there is a separate mechanism to keep the dynamic information up-to-date.
In certain embodiments, the following are the information items retained in the neighborhood database 120
). Note that these items can be supplemented or replaced by other items according to the desired embodiment.
- Network ID: The MAC address of the BS/AP (this is the Key of the database)
- Associated NAS id, NAS address
- Radio type
- In the same IP subnet as the current network
- IP subnet configuration (prefix, gateway addresses)
- Operator name/id
- List of roaming partners
- IPv4 and/or IPv6 supported
- Channel identifier
- Supports fast MIPv4 and/or MIPv6 handovers
- Network address translations (NATs) present
- MIPv4 and/or MIPv6 home address (HA) present
- Current network load
- Geographic location
- Quality of service (QoS) characteristics
- Pre-authentication capability
- Security capabilities
- Pricing plan
- IP multimedia subsystems (IMS) support present
- List of location based services
- Virtual private network (VPN) (IPsec passthrough) support
Various applications can take advantage of this network neighborhood discovery capability. A few exemplary applications are listed as follows.
Key scoping in 2.3 GHz Wireless Broadband (WiBro) fast handoffs: (WiBro is a Korean standard, Telecommunications Technology Association Project Group 302
, and is part of the IEEE 802.16 family of wireless Internet specifications.)
- In order to use the same pairwise master key (PMK), a WiBro MS needs to know if a given BS is managed by a given network access server (NAS). This discovery needs to happen even before the 3-way handshake with the target BS. The NAS ID delivered via DHCP allows a MS to discover the NAS scope.
- The NAS identifier discovered by the MS is used to run pre-authentication with the target NAS even before the MS is handed over to the target network.
Pro-active detection of network attachment (DNA):
- The MS can discover which BSs are connected to the same IP subnet as the currently serving one. That way, as soon as it is attached to one of those, it can readily know that its current IP configuration is still valid.
Reduced scan time:
- By learning the channel information of the target APs, the MS can avoid sequential radio scanning.
Advanced network selection:
- The rich information gathered about the target networks can be used in an advanced network selection scheme. In the absence of process 200, most of the network information cannot be gathered without fully connecting to the target networks.
- Features of Certain Embodiments
Pro-active fast mobile IP handovers:
- By knowing the target foreign agent (FA) or access router in advance, the MS can request bi-casting before it handovers to the target network. Bi-casting is associated with a semi-soft handoff where there is communication with both an old and new point of attachment.
Certain embodiments of the new DHCP process option provide features and advantages not described in prior DHCP options. These features are as follows:
- Currently defined DHCP options provide limited information about only the serving network. Detailed information about the candidate networks is not defined. The new DHCP process option provides detailed information about the candidate networks.
- There is no candidate other than DHCP to provide neighborhood information in a link-layer agnostic way (i.e., All-IP way).
- The new DHCP process option uses a type-length-value (TLV) structure, which allows addition of new attributes as needed.
- New information can be added to the described system design as it become available or needed for a particular application.
While specific blocks, sections, devices, functions and modules may have been set forth above, a skilled technologist will realize that there are many ways to partition the system, and that there are many parts, components, modules or functions that may be substituted for those listed above.
While the above description has pointed out novel features of the invention as applied to various embodiments, the skilled person will understand that various omissions, substitutions, and changes in the form and details of the device or process illustrated may be made without departing from the scope of the invention. Therefore, the scope of the invention is defined by the appended claims rather than by the foregoing description. All variations coming within the meaning and range of equivalency of the claims are embraced within their scope.
 Droms, R., “Dynamic Host Configuration Protocol,” RFC 2131, March 1997.
 Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., Carney, M., “Dynamic Host Configuration Protocol for IPv6 (DHCPv6),” RFC 3315, July 2003.
 IEEE 802.11k Working Group Draft
 Koodli, R. (ed), “Fast Handovers for Mobile IPv6,” work in progress, October 2004.