HK1126919B - Communications method and apparatus using physical attachment point identifiers - Google Patents

Abstract

Methods and apparatus for routing messages between an end node and an access node via another access node are described. Physical layer identification information is used when identifying a remote, e.g., adjacent, access node as a message destination. Thus, when a connection identifier based on one or more physical layer identifiers is available to a wireless terminal, e.g., from one or more downlink signals received from a destination access node, the wireless terminal can use the connection identifier corresponding to the destination node to route a message via an access node with which it has an established uplink connection. Such connection identifier information can be used even when other addressing information, e.g., network layer address information, associated with the destination access node, may not be available to the wireless terminal.

Description

Communication method and apparatus using physical attachment point identifier

Technical Field

The present invention relates to communication systems, and more particularly, to methods and apparatus for routing messages based on physical layer information in a wireless (e.g., cellular) communication network.

Background

The Open Systems Interconnection (OSI) reference model is useful in explaining various communication and routing operations. The OSI reference model includes 7 layers, with the application layer being the topmost layer and the physical layer being the lowest layer. The physical layer is the layer that handles the actual physical connections and the properties of the physical connections in the system. Above the physical layer is a data link layer, sometimes referred to as the link layer. The link layer (layer 2 in the OSI model) is sometimes described as a technology specific transport layer. Above the link layer is the network layer (OSI layer 3), which supports network routing and relaying. The network layer is sometimes referred to as a cladding layer. At the network layer, routing of messages/packets throughout the network is performed, for example, over one or more paths. Different addressing may be used to direct messages and signals at different levels. For example, a network address (e.g., an IP address) may be used to route messages/packets at the network layer level. MAC addresses may be used to control the routing of messages at the data link layer level. At the lowest level of the OSI model (the physical level), one or more physical identifiers are correlated to the actual physical attributes or characteristics of a source or destination device. An understanding of the different communication layers and different addressing techniques for each of the layers will aid in an understanding of the present invention.

Communication systems often include a plurality of network nodes coupled to an access node via which an end node, such as a mobile device, is coupled to the network. The network nodes may be arranged in a hierarchical manner. End nodes typically communicate directly with access nodes over connections that have been established with the access nodes. Such systems typically rely on the presence of a bi-directional communication link between an access node and an end node to support bi-directional communication between the end node and the access node. It should be noted that in such systems the end node is typically not aware of the network layer address of the target destination access node, but may be aware of the information that it may receive on the broadcast channel, which may typically include a physical layer identifier, which is typically not used for message routing in such systems. This approach results in handoff delays and packet loss when the end node is only able to maintain one single bidirectional communication link at the time.

It should therefore be appreciated that there is a need for methods and apparatus that allow an end node that does not have a current uplink communications link to a target access node to communicate with the target access node via another access node with which the end node has a current uplink communications link, even when the end node does not know the network address of the target access node.

In some systems, end nodes are capable of simultaneously maintaining multiple bidirectional communication links with different access nodes. However, such systems typically require the end node to send messages intended for a particular access node with which the end node has a connection over a link directly connected to the particular access node. In some cases, this approach is inefficient because the link, especially when it is a wireless link, tends to fluctuate in quality (e.g., delay and loss characteristics). Thus, when a message needs to be sent to the target destination access node, the link to the target destination access node may not be the best link available to the end node. Typically, this limitation is overcome by resorting to network layer communications, which can be routed via multiple hops because network layer addresses (e.g., IP addresses) are used. This approach of using network layer addresses is also inefficient, especially when messaging involves link layer specific functions, as network layer messages tend to be much larger than link layer messages in some systems. Such inefficient signaling is not well suited for communication over resource constrained airlinks.

It should be appreciated that there is also a need, therefore, for a method that allows an end node to send messages over any of its available wireless communication links independent of the access node for which the message is intended. It is desirable, at least in certain embodiments, that such messages be sent without having to resort to inefficient network layer communications, such as communications involving the use of network layer addresses, such as IP layer addresses, to route information to the destination access node.

Disclosure of Invention

The present invention relates to methods and apparatus for routing messages between an end node and an access node via another access node. The methods and apparatus of the present invention support the use of physical layer identification information when identifying a remote (e.g., neighboring) access node as a message destination. Thus, when a wireless terminal may obtain a connection identifier based on one or more physical layer identifiers from one or more downlink signals received, for example, from a destination access node with which the wireless terminal has an established uplink connection, the wireless terminal may use the connection identifier corresponding to the destination node to route messages via the access node. Such connection identifier information may be used even when other addressing information associated with the destination access node is not available to the wireless terminal, such as network layer address information.

Various novel features are directed to an end node method of receiving broadcast information from an access node and determining a physical attachment point identifier, e.g., a connection identifier corresponding to the access node. Other features relate to transmitting a signal to an access node that includes a connection identifier corresponding to another access node. The connection identifier is based on one or more information that provides information related to a physical layer attachment point. Therefore, according to the present invention, physical layer information can be used as a connection identifier.

According to the present invention, an access node stores information mapping a connection identifier based on physical layer identification information to one or more higher level addresses. Storing the mapping information in the access node. In addition to connection identifiers corresponding to physical layer attachment points of other (e.g., neighboring) access nodes, an access node also includes mapping information corresponding to connection identifiers of physical layer attachment points local to the access node. This allows routing between physically adjacent base stations to be performed based on the physical layer connection identifier without requiring the wireless terminal to transmit a link layer or network layer address over the air when a message to be delivered to a neighboring access node is to be sent via an existing connection with the access node currently serving the wireless terminal.

Accordingly, various features of the present invention are directed to an end node method of receiving a signal from an access node indicating an identifier to access node address resolution failure and causing the end node to send a neighbor advertisement message to establish a new access node neighbor.

While certain features relate to wireless terminal methods and apparatus and novel messages of the present invention stored in a wireless terminal, other features relate to novel access node methods and apparatus. The present invention also relates to data storage devices, such as memory devices, that store one or more of the novel messages of the present invention.

While various embodiments have been discussed in the foregoing summary, it should be understood that not necessarily all embodiments include the same features and that some of the features described above are not required but may be required in some embodiments. In the following detailed description, numerous additional features, embodiments, and benefits of the present invention are discussed.

Drawings

Fig. 1 illustrates a network diagram of an exemplary communication system implemented in accordance with the present invention.

Fig. 2 illustrates an exemplary end node implemented in accordance with the present invention.

Fig. 3 illustrates an exemplary access node implemented in accordance with the present invention.

FIG. 4 illustrates an example connection identifier implemented in accordance with this disclosure.

Fig. 5 illustrates an example message implemented in accordance with this disclosure using the connection identifier of fig. 4.

Fig. 6 illustrates exemplary signaling performed in accordance with the present invention when an end node maintains a bi-directional connection with one access node and is to communicate with another access node.

Fig. 7 illustrates exemplary signaling performed in accordance with the present invention when an end node maintains bidirectional connectivity with multiple access nodes.

Fig. 8 illustrates exemplary signaling performed in accordance with the present invention when an end node triggers a neighborhood discovery process between two access nodes.

FIG. 9 illustrates an example PID to a higher level address resolution table that can be used for mapping between (to/from) PIDs and corresponding higher level addresses.

Detailed Description

The present methods and apparatus for routing messages based on physical layer information, such as physical layer identifiers, can be used to support communication sessions with one or more end nodes, such as mobile devices. The method and apparatus of the present invention may be used with a wide range of communication systems. For example, the present invention may be used with systems that support mobile communication devices, such as notebook computers equipped with modems, PDAs, and various other devices that support wireless interfaces to facilitate device mobility.

Fig. 1 illustrates an exemplary communication system 100, such as a cellular communication network, implemented in accordance with the present invention, comprising a plurality of nodes interconnected by communication links. Exemplary communication system 100 is, for example, a multiple access spread spectrum Orthogonal Frequency Division Multiplexing (OFDM) wireless communication system. The nodes in the exemplary communication system 100 exchange information using signals, e.g., messages, based on a communication protocol, e.g., the Internet Protocol (IP). For example, the communication links of system 100 may be implemented using wires, fiber optic cables, and/or wireless communication techniques. The exemplary communication system 100 includes a plurality of end nodes 144, 146, 144 ', 146 ', 144 ", 146" that access the communication system via a plurality of access nodes 140, 140 ', 140 ". The end nodes 144, 146, 144 ', 146 ', 144 ", 146" may be, for example, wireless communication devices or terminals, while the access nodes 140, 140 ', 140 "may be, for example, base stations. The base station may be implemented as a wireless access router. Exemplary communication system 100 also includes a plurality of other nodes 104, 106, 110, and 112 that are used to provide interconnectivity or to provide specific services or functions. Specifically, the exemplary communication system 100 includes a server 104, the server 104 for supporting the transfer and storage of state regarding end nodes. The server node 104 may be, for example, an AAA server, or it may be a context transfer server, or it may be a server that includes both AAA server functionality and context transfer server functionality.

The example system 100 of fig. 1 depicts a network 102 that includes a server 104 and a node 106, the server 104 and the node 106 being connected to an intermediate network node 110 by corresponding network links 105 and 107, respectively. Intermediate network node 110 in network 102 also provides interconnectivity to network nodes that are external from the perspective of network 102 via network link 111. Network link 111 is connected to another intermediate network node 112, intermediate network node 112 providing further connectivity to a plurality of access nodes 140, 140 ', 140 "via network links 141, 141', 141", respectively.

Each access node 140, 140 ', 140 "is depicted as providing connectivity to a plurality of N end nodes (144, 146), (144 ', 146 '), (144", 146 "), respectively, via corresponding access links (145, 147), (145 ', 147 '), respectively, (145", 147 "). In the exemplary communication system 100, each access node 140, 140', 140 "is depicted as providing access using wireless technology, such as wireless access links. The respective radio coverage area (e.g., communication cell) 148, 148 ', 148 "of each access node 140, 140', 140" is illustrated as a circular area surrounding the corresponding access node.

The exemplary communication system 100 is subsequently used as a basis for the description of various embodiments of the present invention. Alternative embodiments of the present invention include various network topologies where the number and type of network nodes, the number and type of access nodes, the number and type of end nodes, the number and type of servers and other agents, the number and type of links, and the interconnectivity between nodes may differ from the aspects of the exemplary communication system 100 depicted in fig. 1.

In various embodiments of the invention, certain functional entities depicted in fig. 1 may be omitted or combined. The location or placement of these functional entities in the network may also be changed.

Fig. 2 provides a detailed illustration of an exemplary end node 200, e.g., a wireless terminal, e.g., a mobile node, implemented in accordance with the present invention. The example end node 200 depicted in fig. 2 is a detailed representation of an apparatus that may be used as any of the end nodes 144, 146, 144 ', 146', 144 ", 146" depicted in fig. 1. In the fig. 2 embodiment, the end node 200 includes a processor 204, a wireless communication interface 230, a user input/output interface 240 and memory 210 coupled together by bus 206. Thus, the various components of the end node 200 can exchange information, signals and data via the bus 206. The components 204, 206, 210, 230, 240 of the end node 200 are inside the housing 202.

The wireless communication interface 230 provides a mechanism by which the internal components of the end node 200 can send and receive signals to/from external devices and network nodes, such as access nodes. The wireless communication interface 230 includes, for example, a receiver module 232 with a corresponding receive antenna 236 and a transmitter module 234 with a corresponding transmit antenna 238 for coupling the end node 200 to other network nodes, e.g., via wireless communication channels. In certain embodiments, the transmitter module 234 comprises an Orthogonal Frequency Division Multiplexing (OFDM) transmitter.

The exemplary end node 200 also includes a user input device 242, such as a keypad, and a user output device 244, such as a display, coupled to the bus 206 via the user input/output interface 240. Thus, user input/output devices 242, 244 can exchange information, signals and data with other components of the end node 200 via the user input/output interface 240 and bus 206. The user input/output interface 240 and associated devices 242, 244 provide a mechanism by which a user can operate the end node 200 to accomplish various tasks. In particular, the user input device 242 and user output device 244 provide functionality that allows a user to control the end node 200 and applications (e.g., modules, programs, routines, and/or functions) executing in the memory 210 of the end node 200.

The processor 204, under control of various modules (e.g., routines) included in the memory 210, controls operation of the end node 200 to perform various signaling and processing as described below. The modules included in memory 210 are executed at startup or when called by other modules. Modules may exchange data, information, and signals when executed. Modules may also share data and information when executed. In the fig. 2 embodiment, the memory 210 of the end node 200 of the present invention includes a signaling/control module 212 and signaling/control data 214.

The signaling/control module 212 controls processing associated with receiving and sending signals (e.g., messages) for managing state information storage, retrieval, and processing. Signaling/control data 214 includes state information such as parameters, state, and/or other information related to the operation of the end node. In particular, signaling/control data 214 includes configuration information 216, such as end node identification information, and operational information 218, such as information regarding current processing state, state of pending responses, and the like. The module 212 accesses and/or modifies the data 214, such as updating configuration information 216 and/or operational information 218.

The message generation module 251 is responsible for generating messages for various operations of the end node 200. Neighbor notification message 280 and signaling message 281 are exemplary messages generated in accordance with the present invention.

The link selection module 213 is responsible for selecting a link (e.g., the best link) from the plurality of links available to the end node 200 for transmission of the next message ready for transmission by the end node 200. The link selection algorithm is based on various link quality parameters including, but not limited to, at least some of link delay, link channel conditions, link error rate, and link transmission power requirements.

A physical layer attachment Point Identifier (PID) determination module 270 is responsible for determining the PID corresponding to a broadcast signal received from an access node. PID determination module 270 includes cell identification module 271, carrier identification module 272, and sector identification module 273. In some, but not all embodiments, a combination of a cell identifier, a carrier identifier, and a sector identifier is used as a physical attachment point identifier. Each of these identifier elements corresponds to physical layer identification information. For example, the cell identifier identifies a physical cell or cell type. The carrier identifier identifies a physical carrier, such as a carrier frequency or tone block, while the sector identifier identifies a sector in the corresponding cell. Not all this information need be used to implement a PID and the particular elements of a PID may vary depending on the system implementation. For example, in a system that does not use sectorized cells, a sector ID would not be needed. Also, in a single carrier system, the carrier ID may not be needed. In one exemplary system, making a PID determination comprises the steps of: operating the cell identification module 271 to determine a cell identifier; the carrier identification module 272 is operative to determine a carrier identifier; and operating the sector identification module 273 to determine the sector identifier. Thus, it should be appreciated that different signals passing through a single physical transmitter element (e.g., antenna) may correspond to different physical layer attachment points, e.g., each of the different physical layer attachment points may be uniquely identified, at least within a local area, by a combination of physical identifiers. For example, it should be appreciated that a first physical layer attachment point may be identified using a combination of an antenna or sector identifier and a first carrier identifier, while a second physical layer attachment point may be identified using a combination of a second carrier identifier and the same antenna or sector identifier.

Physical layer attachment Point Identifier (PID) information 260 is a PID list (PID 1261, PID 2262) that is the PID determined using PID determination module 260. An example implementation of a physical layer attachment Point Identifier (PID) may be a Connection Identifier (CID), which may be included in a message when sending and/or receiving the message. Specific example CIDs are discussed further below.

The memory 210 also includes a neighbor notification module 290, a message transmission control module 292, and a link establishment module 294. The neighbor notification module 290 is used to transmit neighbor notifications (e.g., neighbor notification messages 280) to the access node. The message transmission control module 292 is used to control the transmitter module 234. Link establishment module 294 is configured to establish a wireless communication link with an access node.

Fig. 3 provides a detailed illustration of an exemplary access node 300 implemented in accordance with the present invention. The exemplary access node 300 depicted in fig. 3 is a detailed representation of an apparatus that may be used as any of the access nodes 140, 140', 140 "depicted in fig. 1. In the fig. 3 embodiment, access node 300 includes a processor 304, a memory 310, a network/internetwork interface 320 and a wireless communication interface 330, coupled together by a bus 306. Accordingly, the various components of the access node 300 can exchange information, signals and data via the bus 306. The components 304, 306, 310, 320, 330 of the access node 300 are inside the housing 302.

The network/internetwork interface 320 provides a mechanism by which the internal components of the access node 300 can send and receive signals to and from external devices and network nodes. The network/internetwork interface 320 includes a receiver module 322 and a transmitter module 324 used for coupling the node 300 to other network nodes (e.g., via copper wires or fiber optic lines). The wireless communication interface 330 also provides a mechanism by which the internal components of the access node 300 can send and receive signals to/from external devices and network nodes, such as end nodes. Wireless communication interface 330 includes, for example, a receiver module 332 with a corresponding receive antenna 336 and a transmitter module 334 with a corresponding transmit antenna 338. The interface 330 is used to couple the access node 300 to other network nodes (e.g., via a wireless communication channel).

The processor 304 controls the operation of the access node 300 under control of various modules (e.g., routines) included in the memory 310 to perform various signaling and processing. The modules included in memory 310 are executed at startup or when called by other modules that may be present in memory 310. Modules may exchange data, information, and signals when executed. Modules may also share data and information when executed.

In the embodiment of fig. 3, the memory 310 of the access node 300 of the present invention comprises: a signal generation module 314 for generating a signal; a packet routing module 350 responsible for routing signals and messages; a mapping module 312, which is responsible for mapping the PID to a network layer address; an address resolution table 311, which includes PID to IP address mappings 317. The memory 310 further includes: an end node identification module 351 that identifies the end node with which the access node 300 is in communication; uplink resource allocation information 340, which is responsible for allocating uplink resources to end nodes, including the resources allocated to end node X341; downlink resource allocation information 345, which is responsible for allocating downlink resources to end nodes, including resources allocated to end node X346.

Referring now briefly to FIG. 9, FIG. 9 illustrates an address resolution table 311' that may be used as the address resolution table 311 shown in FIG. 3. The address resolution table 311' includes PIDs 902, 904, 906, 908, 910, 912 and information indicating corresponding IP addresses 903, 905, 907, 909, 911, and 913, respectively. Each PID is locally unique, e.g., the PIDs of immediately adjacent cells are unique to each other. It should be noted that the content of the PID can vary depending on the physical characteristics of the access node and the number of physical layer attachment points supported by the access node to which the PID corresponds. In the example of fig. 9, PIDs 902, 904 correspond to a first access node (AN 1) that supports two sectors that use the same carrier. Thus, in the case of AN 1, it is sufficient for the PID to include a cell identifier and a sector type identifier to uniquely identify the physical layer attachment point in the cell. PIDs 906, 908, 910 correspond to cells supporting multiple carriers and multiple sectors. Thus, the PID of the access node 2 is implemented as a CID in the same manner as used in the various exemplary embodiments discussed further herein. PID 912 corresponds to a third access node that includes a single sector and uses a single carrier. Thus, it is sufficient that PID 6 corresponding to the third access node only includes a cell identifier, but may also include additional physical layer identifiers (e.g., sector and/or carrier identifiers). From a processing perspective, where a consistent PID format across multiple cells is desired, it may be desirable to include such additional information.

Referring now to fig. 4, fig. 4 illustrates an exemplary Connection Identifier (CID)400 implemented in accordance with the present invention. CID 400 includes: slope 410, which is a cell identifier; a sector 420, which is a sector identifier; and carrier 430, which is a carrier frequency identifier, also referred to as a tone block identifier.

In an exemplary communication system using OFDM technology, in the physical layer, the frequency spectrum is divided into multiple tones and reused for cells and sectors in adjacent geographic areas. To improve interference characteristics, the tones used in each cell/sector hop over time, while different cells and sectors in neighboring geographic areas use different hopping sequences that specify how the tones should hop. The hopping sequence is generated using a predetermined function controlled by two input variables, namely the cell identifier (e.g., slope value) and sector identifier. The sector identifier may be implemented as a sector type identifier that indicates to which of a plurality of possible sector types a particular sector corresponds. In one embodiment, the slope value is an integer from 1 to 112 and the sector identifier value is an integer from 0 to 5. The use of different pairs of slope and sector identifiers by neighboring cells and sectors causes the hopping sequences generated to be different. In one embodiment, all sectors in a cell use the same slope value but different sector identifiers, while adjacent (e.g., physically adjacent) cells use different slope values.

Furthermore, in certain embodiments, the exemplary OFDM communication system uses multiple carriers or tone blocks such that the available tones are grouped into multiple tone blocks. Preferably, the tones in the tone block are consecutive. In one example system, hopping of tones in a given tone block is limited to that tone block. That is, the hopping sequence is such that the tones can hop within the tone block but not across multiple tone blocks. Tone blocks are indexed using carrier identifiers. In one embodiment, the carrier identifier is an integer 0, 1 or 2.

When an end node sets up a connection for wireless networking service, the entity on the network side is an access node (e.g., a base station in a cell/sector) and the connection is defined for a single tone block. Thus, in the above example OFDM communication system, a combination of slope, sector identifier and carrier identifier may be used as a locally unique identifier that identifies a connection for the wireless terminal. Thus, the combination is a connection identifier based on one or more physical layer identifiers. In one embodiment, multiple wireless terminals may have connections with the same base station cell/sector on the same tone block. Those connections typically share the same connection identifier because they are connected to the same physical layer attachment point defined by the combination of cell, sector, and tone block. A communication connection with a particular wireless terminal may be indicated using a combination of the connection identifier and wireless terminal identifier.

Generally, the connection identifier is a number or combination of numbers that uniquely identifies the connection locally. In various embodiments, the number or numbers are physical layer characteristic parameters. In another embodiment, such as an exemplary embodiment of a CDMA communication system, the connection identifier may be a combination of a pseudo-noise (PN) sequence offset and another parameter, such as a carrier identifier if multiple carriers are used.

Fig. 5 illustrates an exemplary message 500 using the connection identifier of fig. 4 in accordance with this disclosure. The exemplary message 500 is a link layer message that includes a CID destination/source address. According to some embodiments of the invention, the CID destination/source address is an optional field in a link layer message. The link layer message 500 includes a Link Layer Control (LLC) type field 510 that identifies the type of message body 530 included in the message 500. CID 520 is a connection ID in the form of connection ID 400 of fig. 4. In one embodiment of the invention, the CID field 520 identifies the destination physical attachment point when sent from an end node to an access node in accordance with the invention and the source physical attachment when sent from an access node to an end node in accordance with the invention.

Fig. 6 illustrates an example communication method and corresponding signaling performed in accordance with various example embodiments of the present disclosure. In fig. 6, end node 630 communicates with access node 620 via access node 610, there is no wireless uplink between end node 630 and access node 620 and the end node does not have to know the IP address of access node 620. The signaling is illustrated in the context of the exemplary system 100 illustrated in fig. 1. Access nodes 610 and 620 are similar to access nodes 140, 140' and 140 "of system 100 in fig. 1 and are implemented in accordance with access node 300 of fig. 3. End node 630 is similar to end nodes 144, 146, 144 ', 146', 144 "and 146" of system 100 in fig. 1 and is implemented in accordance with end node 200 in fig. 2.

In fig. 6, end node 630 maintains a bidirectional link with access node 610, meaning that it can send messages to access node 610 and receive messages from access node 610. End node 630 in fig. 6, while in transmission range of access node 620, does not have an uplink with access node 620. This means that while end node 630 can receive and process broadcast information (e.g., broadcast message 640) sent by access node 620, end node 630 cannot send messages over the air to access node 620 and access node 620 cannot receive and process messages sent by end node 630 over the air interface. In one embodiment of the invention this may be due to insufficient timing synchronization by end node 630 with access node 620. Due to certain limitations (e.g., limited hardware capabilities), end node 630 may not be able to establish an uplink connection with access node 620 while end node 630 currently has a bidirectional connection with access node 610. In one embodiment, the uplinks used by access node 610 and access node 620 are on different carriers, e.g., the frequency band of the uplink used by access node 610 is different than the frequency band of the uplink used by access node 620. For example, if end node 630 can only generate uplink signals within one frequency band at a given time because end node 630 only has a Radio Frequency (RF) chain for cost considerations, end node 630 cannot simultaneously maintain two uplink connections within two separate frequency bands. In another embodiment, where the uplinks used by access nodes 610 and 620 are in the same frequency band, the two uplinks may not be synchronized in time because the two access nodes are not synchronized in time or because of differences in propagation delays of signals from the end node 630 to access nodes 610 and 620. For example, if end node 630 can generate only one uplink signal per time according to one timing synchronization scheme because end node 630 has a single digital processing chain that is limited to one timing scheme at a time, end node 630 cannot simultaneously maintain two uplink connections when the timing synchronization of the connections is insufficient with respect to each other.

End node 630 receives broadcast signal 640 transmitted by access node 620. According to the described embodiment of the invention, signal 640 is sufficient to determine a connection ID (similar to CID 400 of fig. 4) corresponding to a particular physical attachment of access node 620 transmitting broadcast signal 640. The signals or signals 640 may comprise beacon and/or pilot signals, which may be transmitted during one or more symbol transmission time periods.

End node 630 transmits message 650 to access node 610. In an exemplary embodiment of the present invention, the message 650 is the same as or similar to the exemplary message 500 of fig. 5. The CID field (equivalent to CID 520 of fig. 5) of the message 650 is set to a connection identifier that identifies the physical attachment point of the access node 620 that broadcasts the signal 640. Thus, while the message 650 is sent to access node 610, it is destined for access node 620. It should be noted that since end node 630 and access node 620 in the fig. 6 example do not have an uplink, message 650 cannot be sent directly to the access node 620.

Access node 610 receives message 650 and examines the CID field of message 650 (corresponding to CID 520 of fig. 5) and recognizes from the CID stored to the link layer identification information that it does not identify one of its own physical attachment points. In this case, access node 610 searches its memory for the CID of message 650 to find a mapping to a corresponding higher layer identifier (e.g., IP address) for access node 620.

For example, a base station comprising multiple sectors operating under a single link layer controller and/or multiple carriers used under a single link layer controller may have multiple CIDs corresponding to a link layer identifier corresponding to a single link layer controller. In embodiments where a separate link layer controller is used for each sector and/or carrier, a different link layer identifier may be used for each of the different sectors and/or carriers. In some embodiments, there is a one-to-one mapping between physical attachment points and link layers, but this is not required and there may be several physical attachment points operating under a single link layer. Thus, multiple physical layer identifiers may correspond to the same link layer link identifier, but each physical layer identifier connection identifier typically maps to at most a single link layer link identifier.

Assuming a mapping to a higher layer address is found, access node 610 encapsulates at least part of message 650 into a network layer message 660 including a destination address set to the identifier of access node 620 and transmits the message 660 to access node 620. Message 660 also includes end node 630 identifier, which is one of end node 630IP address, end node 630 Network Access Identifier (NAI), and temporary identifier, in accordance with the embodiment, in accordance with the present invention. Access node 620 receives the message 660 and extracts the encapsulated portion of message 650 therefrom. Access node 620 examines the CID field of the extracted encapsulated portion of message 650 and recognizes that the CID field identifies one of its own physical attachment points.

Access node 620 sends message 670, which includes at least a portion of message 650 received by access node 620 encapsulated in message 660. The message 670 also includes an end node 630 identifier similar to the one included in message 660. Access node 610 then receives message 670 and determines by examining the included end node identifier that message 670 encapsulates message 680 destined for end node 630. Access node 610 then sends message 680, which includes at least part of message 670. Message 680 includes the CID of the physical attachment point of access node 620 broadcasting signal 640, in accordance with the present invention.

End node 630 receives message 680 from access node 610 but by examining the CID field included in said message 680 (e.g., by comparing it to stored CID information), it decides that message 680 originated from access node 620 in response to message 650 sent earlier to access node 620.

Fig. 7 illustrates exemplary signaling performed in accordance with various embodiments of the invention. The signaling is illustrated in the context of the exemplary system 100 illustrated in fig. 1. End node 710 is a simplified depiction of the end node 200 of fig. 2 and is the same as or similar to the end node 144, 146, 144 ', 146', 144 ", 146" of the system 100 in fig. 1. Access nodes 740 and 750 are similar to access nodes 140, 140', and 140 "of system 100 in fig. 1 and are implemented using access node 300 of fig. 3. In fig. 7, end node 710 includes a message generation module 720 and a link selection module 730. Message generation module 720 of fig. 7 may be used by an application running in end node 710 to generate a message according to its purpose. For example, a connection control protocol application may be included in end node 710 and made active, allowing end node 710 to communicate with access nodes for the purpose of creating, disconnecting and/or modifying links between end node 710 and one or both of access nodes 740, 750. Another example is a quality of service (QoS) application that may be included in end node 710. The QOS application, when present, can modify QOS characteristics of the various links of end node 710. Link selection module 730 of fig. 7 measures various metrics for the quality of the connection, including link delay, link channel conditions, link error rate, and link transmission power requirements, to determine (e.g., on a message-by-message basis or at a particular point in time) which of the available links is most appropriate for transmission of the next message.

The resulting link quality information may be used (and in various embodiments) to determine which link of multiple simultaneous links the message should be transmitted to at a particular point in time.

In fig. 7, end node 710 maintains a bidirectional link with access nodes 740 and 750, meaning that it can send messages to access nodes 740 and 750 and receive messages from access nodes 740 and 750. In this embodiment of the invention message generation module 720 of end node 710 generates message 759, the ultimate destination of which is access node 740. Message 759 is first sent in link selection module 730 of end node 710. Link selection module 730 selects the link between the links to access nodes 740 and 750 over which the next message will be transmitted. The link determination function is based on link characteristics including at least one of link delay, link channel conditions, link error rate, and link transmission power requirements.

In the exemplary embodiment of the invention depicted in fig. 7, link selection module 730 selects a link to access node 740 and transmits message 760 therethrough. Message 760 comprises at least some portion of message 759 and, in some embodiments of the invention, message 760 comprises additional fields for transmitting messages over the link between end node 710 and access node 740. For example, in some embodiments, the additional field is a link framing field. Since the ultimate destination of messages 759 and 760 is access node 740, access node 740 receives message 760, processes the received message and responds by, for example, transmitting message 765 to end node 710. End node 710 receives message 765 and delivers it to the message generation module as message 766. Message generation module 720 generates a second message 769, the ultimate destination of which is access node 740. Message 769 is sent to link selection module 730 which selects the link over which message 769 will be transmitted. In this embodiment of the invention, a link to access node 750 is selected and message 770 is transmitted to access node 750. Message 770 comprises at least a portion of message 769 and, in some embodiments of the invention, comprises additional fields for transmitting the message over the link between end nodes 710 and 750. For example, in some embodiments, the additional field is a link framing field.

In one embodiment of the invention, link selection module 730 adds an identifier of access node 740 (e.g., a physical attachment point identifier) along with at least a portion of message 769 to message 770, because the link selected by link selection module 730 for transmission of message 770 does not correspond to the ultimate destination of message 770, which is access node 740. In another embodiment of the present invention, the link selection module adds an identifier of the final destination of messages 760 and 770 before they transmit the messages 760 and 770, regardless of which link is selected for their transmission. In other embodiments of the present invention, messages 759, 769 include an identifier of their final destination. For example, in the example of the exemplary embodiment of fig. 7, the identifier of the final destination corresponds to access node 740.

In one exemplary embodiment of the invention, message 770 is implemented according to message 500 of fig. 5, where CID field 520 identifies access node 740. Access node 750 receives message 770 and processes it. By examining the final destination of message 770, such as the physical attachment point identifier in CID field 520 of message 500 of fig. 5, access node 750 determines that message 770 is not intended for itself but is intended for some other node identified by the final destination identifier, such as a CID in the CID field. The access node 750 looks up the physical attachment Point Identifier (PID) included in message 770 in its address resolution table (see address resolution table 311 in access node 300 of fig. 3) to find the network address (e.g., IP address) corresponding to the PID included in message 770.

Access node 750 encapsulates at least a portion of message 770 in an appropriate network layer header and transmits message 775 to access node 740. Message 775 includes at least: a portion of message 770 and at least some of the IP address of access node 740. Further, message 775 may include some or all of the following in various embodiments: the IP address of access node 750, the PID of access node 740 included in message 770, the PID of access node 750 via which message 770 was received, the access node 710 identifier used for encapsulation (also referred to as tunneling) of messages between access node 750 and access node 740, and the session identifier. Access node 740 receives message 775 which it considers intended for itself according to the destination PID included in message 775.

In one embodiment of the invention, access node 740 responds by transmitting message 780, which includes at least part of message 775. Access node 750 receives message 780, which includes end node 710 identifier, and sends message 785 to end node 710. Message 785 includes at least a portion of message 780. End node 710 receives message 785 and forwards message 786 to message generation module 720.

In another embodiment of the invention access node 740 responds by transmitting message 780' including at least part of message 775 to end node 710. Message 780' is transmitted via the direct link between access node 740 and end node 710.

Fig. 8 illustrates exemplary signaling performed in accordance with an exemplary embodiment of the present invention, wherein an end node is used as part of a neighbor discovery and CID routing information update process. The signaling is illustrated in the context of an exemplary system, such as system 100 illustrated in fig. 1. The end node 810 is a simplified depiction of the end node 200 of fig. 2 and is the same as or similar to the end nodes 144, 146, 144 ', 146', 144 ", 146" of the system 100 in fig. 1. Access nodes 840 and 850 are the same as or similar to access nodes 140, 140', and 140 "of system 100 in fig. 1, and may be implemented, for example, using access nodes of the type illustrated in fig. 3. In the example of fig. 8, end node 810 has a bidirectional communications link with access node 840 allowing it to send messages to access node 840 and receive messages from access node 840.

In fig. 8, end node 810 generates and transmits message 860 to access node 840. Message 860 includes an identifier that identifies access node 850 as the destination for the message. Access node 840 receives message 860 and attempts to resolve the access node 850 identifier included in the message to a network address by searching its address resolution table (e.g., address resolution table 311 of access node 300 of fig. 3). In the example of fig. 8, access node 840 cannot resolve the identifier. Access node 840 then transmits message 865 to end node 810. Message 865 includes an indication that the message is not routable due to a resolution failure.

In one embodiment of the invention, end node 810 now establishes a bi-directional communication link with access node 850 by exchanging various messages, shown in fig. 8 as double-headed arrow messages 870. However, this need not be the case if there is already a bi-directional link with access node 850. In another example of use of the invention, end node 810 already has a bidirectional link with access node 850 in addition to the link with access node 840.

Using the link with access node 850, end node 810 transmits a new neighbor notification message 875 to access node 850. Message 875 includes at least an identifier of access node 840 and the network layer address of access node 840. In this manner, access node 850 is supplied with both an identifier, such as the PID of access node 840, and a corresponding link layer address, such as a MAC address, which access node 850 may address and store for future resolution of the physical layer to the network layer identifier. In one embodiment of the invention, the access node 840 identifier is a physical attachment point identifier; in another embodiment of the invention, it is a link layer identifier. End node 810 is aware of the network layer identifier of access node 840 from communication message 897 communicated to end node 810 during or after establishment of a link with access node 840.

In an alternative embodiment of the present invention end node 810 sends message 875' instead of message 875. Message 875' has the same or similar message content as message 875, but it is sent to access node 850 via access node 840 instead of directly to access node 850. Access node 840 then routes message 875' to access node 850 as message 875 ". Note that unlike message 860, message 875' is a network layer message that includes access node 850 network address as its destination. End node 810 knows the network layer address of access node 850 from communication messages 899 communicated during or after establishment of a link with access node 850. For this reason, access node 840 may route message 875 "to access node 850 using the network address (e.g., IP address) of access node 850 without having to perform a CID to address resolution operation.

Access node 850 receives message 875 and sends new neighbor generation message 880 to the network address of access node 840 retrieved from message 875. Message 880 includes a connection identifier to the mapping of the network layer address of access node 850. In another embodiment of the present invention, message 880 includes a link layer identifier to a mapping of access node 850's network layer address. In another embodiment of the present invention message 880 includes additional neighbor information to accommodate end node handoffs including, but not limited to: a tunneling address and a tunneling session identifier for packet redirection between access nodes 840 and 850; access node 850 capabilities with respect to quality of service, load, protocol, and supported applications. Access node 840 receives message 880 and stores information included in message 880 in its memory, e.g., for future use in CID to network address resolution operations. Access node 840 responds with message 882 acknowledging receipt of the information included in message 880.

In one embodiment of the invention, access node 840 includes in message 882 some of the following: a mapped connection identifier to a network layer address of access node 850; a link layer identifier to a mapping of a network layer address of access node 850; neighbor information for accommodating end node handoffs includes, but is not limited to, tunneling addresses and tunneling session identifiers for packet redirection between access nodes 840 and 850 and/or information indicating the capabilities of access node 840 with respect to quality of service, load, protocol, and supported applications. Access node 840 receives message 880 and stores information included in message 880 in its memory (or e.g., for future use in routing messages). In this particular embodiment of the present invention, messages 883 and 884 are not used.

In another embodiment of the present invention access node 840 message 882 includes an acknowledgement of the receipt of the information included in message 880. In this embodiment of the invention, access node 840 sends message 883 including at least some of the following: a mapped connection identifier to a network layer address of access node 850; a link layer identifier to a mapping of a network layer address of access node 850; neighbor information for accommodating end node handoffs, including but not limited to: a tunneling address and a tunneling session identifier for packet redirection between access nodes 840 and 850; access node 840 capabilities with respect to quality of service, load, protocol, and supported applications. Access node 850 receives message 883 and stores the information included in message 883 in its memory, e.g., for future use. Access node 850 responds with a message 884 acknowledging receipt of the information.

After exchanging neighbor information and identifier-to-address mappings between access nodes 840 and 850 via messages 880, 882 and optionally 883 and 884, end node 810 sends message 890 to access node 840. Similar to message 860, in one embodiment of the invention, message 890 is also the same as or similar to message 500 of FIG. 5. Message 890 identifies access node 850 as its final destination. Access node 840 receives message 890, searches its memory for a mapping between access node 850 identifiers and the network address of said node 850 and finds said earlier filled network address by message 880 in its address resolution table. Access node 840 encapsulates message 890 according to the information in the resolution table and sends it to access node 850 in the form of message 891. Access node 850 again responds with message 892 using the information in its address resolution table and message 891. Access node 840 sends message 893 to end node 810 including at least part of message 892 received from access node 850 completing the communication exchange between end node 810 and access node 850 via access node 840.

In the manner described above, using messages from end node 810, access nodes 840 and 850 have address and/or PID information about each other that can be used to route subsequently received messages. Thus, when an access node is added to the network, the end node can discover its presence from the broadcast signal and notify the access node of the new neighbor. As part of the notification process, sufficient address information is assigned to facilitate network PID based message routing after the notification process has been completed.

In various embodiments nodes described herein are implemented using one or more modules to perform the steps corresponding to one or more methods of the present invention, such as signal processing, message generation, and/or transmission steps. Thus, in certain embodiments, various features of the present invention are implemented using modules. Such modules may be implemented using software, hardware, or a combination of software and hardware. Many of the above described methods or method steps can be implemented using machine executable instructions, such as software, included in a machine readable medium such as a memory device, e.g., RAM, floppy disk, etc. to control a machine, e.g., general purpose computer with or without additional hardware, to implement all or portions of the above described methods, e.g., in one or more nodes. Accordingly, among other things, the disclosure relates to machine-readable media comprising machine executable instructions that cause a machine, such as a processor and associated hardware, to perform one or more steps of the above-described methods.

In view of the above description of the present invention, many additional variations on the method and apparatus of the present invention described above will be apparent to those skilled in the art. Such variations are to be considered within the scope of the invention. The methods and apparatus of the present invention may be, and in various embodiments are, used with CDMA, Orthogonal Frequency Division Multiplexing (OFDM), or various other types of communications techniques which may be used to provide wireless communications links between access nodes and mobile nodes. In some embodiments the access nodes are implemented as base stations which establish communications links with mobile nodes using OFDM and/or CDMA. In various embodiments the mobile nodes are implemented as notebook computers, Personal Data Assistants (PDAs), or other portable devices including receiver/transmitter circuits and logic and/or routines, for implementing the methods of the present invention.

Claims (37)

1. A communications method for use in a system comprising an end node, a first access node and a second access node, the method comprising:

operating the end node to receive broadcast information from the second access node;

operating the end node to determine a physical attachment point identifier from the broadcast information; and

operating the end node to transmit a first signal comprising the physical attachment point identifier to the first access node, wherein the first signal is destined for the second access node.

2. The method of claim 1, wherein transmitting the first signal comprises transmitting the signal via a wireless communication link.

3. The method of claim 2 wherein the end node is within a broadcast coverage area, the first and second access nodes each broadcasting a signal into the broadcast coverage area.

4. The method of claim 2, wherein the end node has a bidirectional communication link with the first access node and at least an uplink with the second access node.

5. The method of claim 2, wherein the end node has a bidirectional communication link with the first access node and no uplink with the second access node.

6. The method of claim 2, wherein the broadcast information comprises a plurality of beacon signals.

7. The method of claim 6, wherein said step of operating said end node to determine a physical attachment point identifier comprises determining from said received beacon signal:

a first identifier, which is a cell identifier.

8. The method of claim 7, wherein the step of operating the end node to determine a physical attachment point identifier further comprises:

determining a second identifier from the received beacon signal, the second identifier being a carrier identifier.

9. The method of claim 8, wherein the step of operating the end node to determine a physical attachment point identifier further comprises:

determining a third identifier from the received beacon signal, the third identifier being a sector identifier.

10. The method of claim 6 wherein the step of operating the end node to determine a physical attachment point identifier comprises determining from the received beacon signal at least two of the following three identifiers corresponding to the second access node: i) a cell identifier, ii) a carrier identifier, and iii) a sector identifier; and

wherein the step of transmitting a first signal comprises communicating a physical attachment point identifier comprising the at least two determined identifiers to the first access node.

11. The method of claim 10, further comprising:

operating the end node to receive a signal from the first access node comprising a message source identifier comprising at least the two determined identifiers corresponding to the second access node.

12. The method of claim 10, wherein the physical attachment point identifier identifies a physical attachment point at the second access node, the physical attachment point identifier being unique within an overlapping end node reception area.

13. The method of claim 1, wherein the first and second access nodes are base stations; and is

Wherein operating the end node for transmission comprises operating the end node for transmission of OFDM signals.

14. The method of claim 10, further comprising:

operating the first access node to receive the first signal;

operating the first access node to determine a network layer address corresponding to the physical attachment point identifier included in the first signal; and

operating the first access node to transmit a packet comprising the determined network layer address as a destination address and comprising at least some information obtained from the first signal.

15. The method of claim 14 wherein said packet further comprises an end node identifier identifying said end node that transmitted said first signal.

16. The method of claim 15 wherein the first signal is a first message that does not include an end node identifier, the first signal communicated using uplink signaling resources dedicated to the end node, the method further comprising:

operating the first access node to determine the end node identifier corresponding to the first signal; and is

Wherein the first access node includes the determined end node identifier in the transmitted packet.

17. The method of claim 16, further comprising:

operating the first access node to receive a packet from the second access node comprising the end node identifier and the physical attachment point identifier.

18. The method of claim 17, further comprising:

operating the first access node to transmit a signal to the end node, the signal comprising the physical attachment point identifier and at least some information obtained from the packet received from the second access node.

19. The method of claim 18 wherein said signals transmitted to said end nodes are transmitted using communications resources dedicated to said end nodes and do not include end node identifiers.

20. A wireless terminal, comprising:

a first receiver module for receiving broadcast information from a second access node;

a physical attachment point identifier determination module for determining a physical attachment point identifier from the broadcast information; and

a first transmitter module to transmit a first signal comprising the physical attachment point identifier to a first access node, wherein the first signal is destined for the second access node.

21. The wireless terminal of claim 20, wherein said transmitter is a wireless transmitter for transmitting said first signal as an OFDM signal via a wireless communication link.

22. The wireless terminal of claim 21, wherein the wireless terminal is within a broadcast coverage area, the first and second access nodes each broadcasting a signal into the broadcast coverage area; and is

Wherein the end node has a bidirectional communication link with the first access node and no uplink with the second access node.

23. The wireless terminal of claim 21, wherein said broadcast information includes a plurality of beacon signals, and

wherein the physical attachment point identifier determination module comprises a cell identifier determination module for determining a first identifier from one or more of the received beacon signals, the first identifier being a cell identifier.

24. The wireless terminal of claim 23, wherein said physical attachment point identifier determination module further comprises a carrier identifier determination module for determining a second identifier from one or more of said received beacon signals, said second identifier being a carrier identifier.

25. The wireless terminal of claim 24, wherein said identifier determination module further comprises a sector identifier module for determining a third identifier from one or more of said received beacon signals, said third identifier being a sector identifier.

26. A method of operating a first access node, the method comprising:

receiving a first signal from an end node;

determining a network layer address corresponding to a physical attachment point identifier included in the first signal; and

transmitting a packet comprising the determined network layer address as a destination address and comprising at least some information obtained from the first signal.

27. The method of claim 26 wherein said packet further comprises an end node identifier identifying said end node that transmitted said first signal.

28. The method of claim 27 wherein the first signal is a first message that does not include an end node identifier, the first signal communicated using uplink signaling resources dedicated to the end node, the method further comprising:

determining the end node identifier corresponding to the first signal; and

including said determined end node identifier in said transmitted packet.

29. The method of claim 28, further comprising:

receiving a packet from a second access node comprising the end node identifier and the physical attachment point identifier.

30. The method of claim 29, further comprising:

transmitting a signal to the end node, the signal comprising the physical attachment point identifier and at least some information obtained from the packet received from the second access node.

31. The method of claim 30 wherein said signals transmitted to said end nodes are transmitted using communications resources dedicated to said end nodes and do not include end node identifiers.

32. A base station, comprising:

a receiver module for receiving a first signal comprising a physical attachment point identifier from a wireless terminal;

an address resolution table comprising information mapping at least one physical attachment point identifier to a network layer address;

a mapping module to determine a network layer address corresponding to the physical attachment point identifier included in the first signal from the address resolution table; and

a network interface module for transmitting a packet comprising the determined network layer address as a destination address and comprising at least some information obtained from the first signal.

33. The base station of claim 32, further comprising:

a signal generation module for generating the packet including the determined network layer address and for including in the packet an end node identifier identifying the wireless terminal that transmitted the first signal.

34. The base station of claim 33, wherein said first signal is a first message that does not include an end node identifier;

the base station further comprises:

a memory comprising stored resource allocation information identifying end nodes to which uplink resources have been allocated;

an end node identification module for determining an end node identifier corresponding to an end node to which uplink resources used to communicate the received first signal were dedicated; and is

Wherein the signal generation module includes the determined end node identifier in the transmitted packet.

35. The base station of claim 35, further comprising:

a packet routing module for routing packets including the end node identifier and the physical attachment point identifier in accordance with the physical attachment point identifier.

36. The base station of claim 35, further comprising:

a transmission module for transmitting a signal to the end node comprising the physical attachment point identifier and at least some information obtained from one or more packets received from another access node.

37. The base station of claim 36, wherein the memory further comprises downlink resource allocation information; and is

Wherein said signals transmitted to said end node are transmitted using downlink communications resources dedicated to said end node and do not include an end node identifier.