HK1141370A - Method and apparatus for handoff between access systems - Google Patents

Description

Method and apparatus for handover between access systems

Claiming priority based on 35U.S.C. § 119

This patent application claims priority to provisional application No.60/895,365 entitled "international patent applications," filed on 3, 16, 2007, which is assigned to the assignee of the present application and is expressly incorporated herein by reference.

Technical Field

The following description relates generally to wireless communications, and more particularly to methods and apparatus for a session handoff procedure between a source access system and a target access system.

Background

Wireless network systems have become a popular way for communicating with each other on a global scale. Wireless communication devices, such as cellular telephones, personal digital assistants, and the like, have become smaller and more powerful in order to meet user demands and to improve portability and convenience. Users have become dependent on these devices, requiring reliable service, expanded coverage areas, additional services (e.g., web browsing capabilities), and ever decreasing size and cost of these devices.

In particular, as wireless technology continues to advance, the development of mobile services will continue to evolve into richer, more attractive mobile and converged services. As end users demand more and higher quality multimedia content in all environments, the evolution of device technology will continually facilitate increased consumption of data usage. For example, over the past few years, wireless communication technology has evolved from analog-driven systems to digital systems. In general, in conventional analog systems, analog signals are relayed on the forward and reverse links, and a large amount of bandwidth is required in order to be able to transmit and receive signals while having a suitable quality. Because the analog signal is continuous in time and space, no status messages (e.g., messages indicating receipt or non-receipt of data) are generated. In contrast, packet-switched systems allow analog signals to be converted to data packets and transmitted by way of physical channels between Access Terminals (ATs) and base stations, routers, and the like. Further, digital data may be relayed in its natural form (e.g., text, internet data, etc.) by employing a packet-switched network.

Accordingly, digital wireless communication systems are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasting, and so on. Such systems typically employ an access network that connects multiple access terminals to a Wide Area Network (WAN) by sharing the available network resources. The access network is typically implemented with a plurality of access points dispersed throughout a geographic coverage area. In addition, the geographic coverage area may be divided into cells, with one access point in each cell. Likewise, a cell may be further divided into sectors. However, in this system architecture, providing efficient handoff between access systems that do not share the same communication procedures and policies becomes a challenging task.

Disclosure of Invention

The following presents a simplified summary in order to provide a basic understanding of the described aspects. This summary is not an extensive overview and is intended to neither identify key or critical elements nor delineate the scope of such aspects. Its purpose is to present some concepts of the described aspects in a simplified form as a prelude to the more detailed description that is presented later.

The described aspects support handover pre-set and execution and re-routing of data packets between networks (e.g., heterogeneous networks) by employing inter-system handover control components. The inter-system handoff control component can facilitate handoff of a session from a source access system to a target access system during various phases of handoff preparation and handoff execution by enabling packet tunneling from an AT, through the source access system, to the target access system. For example, the AT may operate in a dual mode stack and the air interface may be capable of transmitting data over one technology. Thus, the AT utilizes pre-provisioning through the tunnel to minimize the need to complete the procedure AT the handoff time.

Thus, the inter-system handoff control component can pre-provision a tunnel as part of a session negotiation between the AT and the target access system, wherein packets are transmitted (e.g., transparently or non-transparently) via the source access system (e.g., to reduce interruptions during handoff and alleviate the need to perform session establishment during handoff). It should be appreciated that the source access system is typically not engaged during session negotiation between the AT and the target access system because the source access system is considered a different system (e.g., a heterogeneous system that employs different technologies and/or communication procedures and protocols) than the AT and the target access system. Further, tunneled packets may be dedicated to handover pre-set and handover execution in the target system, and such tunneled packets may be transported over IP or over the link layer. For example, the packets may relate to signaling messages associated with the target access system, messages specific to the target RAN, signaling related to pre-provisioning of an IP address in the target access system, related authentication and authorization, and the like.

In a related aspect, during a handover preparation phase, a tunnel may be established from the AT to the source access system, wherein from the perspective of the AT, inter-system communication occurs between the two access systems, and signaling of the "mobile-target access system" occurs over the tunnel. Such tunneling may also be accompanied by the establishment of other tunnels to the target access system, depending on the type of tunneling involved (e.g., whether tunneling occurs at the data link layer). The source access system may also specify a target access system based on the pilot report, where the AT may then communicate with the target access system and establish a negotiation procedure.

According to one method, initially, an AT (e.g., mobile device) communicates with a source access system and utilizes the procedures/techniques of the source access system. When a predetermined event is triggered, a handover preparation phase is initiated in which the source access system may be informed of the request to handover the session to the target access system (which employs a different set of procedures/techniques than the source access system). The notification may be triggered based on the weakening of the pilot signal and/or an announcement from the target access system indicating that the AT has reached the coverage edge of the source system, and handover preparation may be initiated. The handover preparation phase may also include pre-provisioning of a Radio Access Network (RAN) associated with the target system.

Subsequently, a target connection preparation phase occurs, which may be based on a trigger at the source access system or at the target access system, such as a predetermined event related to pilot signal information. Thus, the AT may request air interface resources and further include radio resource allocation from the target access system to the AT. Once the AT receives the resulting assignment in the tunnel, the AT may acquire the target access system and transfer the packet to the target access system. Thus, during handover execution or completion, the AT acquires the target access system over the air and IP traffic is redirected to the AT, where packets may be transmitted (transparently or non-transparently) via the source access system. An exemplary handoff between such heterogeneous access systems may include a handoff between the following protocols: ultra Mobile Broadband (UMB) and High Rate Packet Data (HRPD); WiMax/HRPD; long Term Evolution (LTE)/HRPD, where the system architecture may implement Internet Protocol (IP) mobility using client mobile IP to actively prepare the mobile station for handoff.

To the accomplishment of the foregoing and related ends, certain illustrative aspects are described herein in connection with the following description and the annexed drawings. These aspects are indicative, however, of but a few of the various ways in which the principles of the disclosed subject matter may be employed and the claimed subject matter is intended to include all such aspects and their equivalents. Other advantages and novel features may become apparent from the following detailed description when considered in conjunction with the drawings.

Drawings

Fig. 1 illustrates an exemplary inter-system handoff control component that enables handing off a session from a source access system to a target access system.

Fig. 2 illustrates a particular aspect in which a handover preparation component implements tunneling from an AT to a target access system.

Fig. 3 illustrates packet re-routing to enable handover pre-provisioning/execution between heterogeneous networks.

Fig. 4 illustrates another method of rerouting packets for handover pre-setup/execution between heterogeneous networks in accordance with an aspect.

Fig. 5 illustrates a related methodology of session handoff in accordance with another aspect.

Fig. 6 illustrates an exemplary block diagram for interaction between a source access system and a target access system.

Fig. 7 illustrates an exemplary call flow that enables rerouting of packets for handover setup/execution and rerouting of data packets in heterogeneous networks.

Fig. 8 illustrates an example heterogeneous wireless communication system in accordance with a related aspect.

Fig. 9 illustrates a particular system that facilitates transferring data between heterogeneous access systems via L2 (data link layer) tunneling established by a mobile unit when a handoff is requested.

Fig. 10 illustrates a system that can be employed to transmit data to an access terminal before and after a handoff in layer L2.

Fig. 11 illustrates a system that can be employed to receive a handoff indication and/or transmit data to a corresponding access terminal.

Detailed Description

Various aspects are now described with reference to the drawings. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects. It may be evident, however, that such aspect(s) may be practiced without these specific details.

As used in this application, the terms "component," "module," "system," and the like are intended to include a computer-related entity, such as but not limited to hardware, firmware, a combination of hardware and software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a computing device and the computing device can be a component. One or more components may reside within a process and/or thread of execution and a component may be localized on one computer and/or distributed between two or more computers. In addition, these components can execute from various computer readable media having various data structures stored thereon. The components may communicate by way of local and/or remote processes such as in accordance with a signal having one or more data packets (e.g., data from one component interacting with another component in a local system, distributed system, and/or across a network such as the internet with other systems by way of the signal).

Further, various aspects are described herein in connection with a terminal, which may be a wired terminal or a wireless terminal. A terminal can also be called a system, device, subscriber unit, subscriber station, mobile device, remote station, remote terminal, access terminal, user terminal, communication device, user agent, user device, or User Equipment (UE). A wireless terminal may be a cellular telephone, a satellite telephone, a cordless telephone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA), a handheld device having wireless connection capability, a computing device, or other processing device connected to a wireless modem. Moreover, various aspects are described in connection with a base station. A base station may be utilized for communicating with wireless terminal(s) and may also be referred to as an access point, a node B, or some other terminology.

Furthermore, the word "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless explicitly stated or clear from the context, the statement "X employs A or B" is intended to mean any of the normal inclusive permutations. That is, the statement "X employs A or B" satisfies any of the following: x is A; b is used as X; or X uses both A and B. Furthermore, the articles "a" and "an" as used in this specification and the appended claims are generally to be construed to mean "one or more" unless specified otherwise or clear from context to be directed to a singular form.

The techniques described herein may be used for various wireless communication networks such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other systems. The terms "system" and "network" are often used interchangeably. A CDMA system may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), CDMA2000, etc. UTRA includes wideband CDMA (W-CDMA) and other variants of CDMA. Further, cdma2000 covers IS-2000, IS-95 and IS-856 standards. TDMA systems may implement wireless technologies such as global system for mobile communications (GSM). OFDMA systems may implement methods such as evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11(Wi-Fi), IEEE 802.16(WiMAX), IEEE 802.20, and,And so on. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). 3GPP Long Term Evolution (LTE) is an upcoming release of UMTS that uses E-UTRA, which employs OFDMA on the downlink and SC-FDMA on the uplink. UTRA, E-UTRA, UMTS, LTE, and GSM are described in documents of the organization entitled "third Generation partnership project" (3 GPP). Further, cdma2000 and UMB are described in documents of the organization entitled "third generation partnership project 2" (3GPP 2).

Various aspects or features are presented in terms of systems that may include a number of devices, components, modules, and the like. It is to be understood and appreciated that the various systems may include additional devices, components, modules, etc. and/or may not include all of the devices, components, modules etc. discussed in connection with the figures. Combinations of these schemes may also be used.

Fig. 1 illustrates a network system 100 that enables handover pre-provisioning/execution and re-routing of data packets between networks (e.g., heterogeneous networks) and interworking between a source access system 110 and a target access system 112. The system 100 can pre-establish a tunnel to the target access system 112 as part of a session handoff between heterogeneous access systems (i.e., the source access system 110 and the target access system 112). The inter-system handover control component 115 may facilitate such session handover during various phases by employing a handover preparation component 152 and a handover execution component 154. Thus, tunneling can be implemented from an AT 104 operating in dual mode to accommodate both the source access system 110 and the target access system 112, even though, for example, the AT may only be able to transmit in one access system AT any given time. An exemplary handoff between such heterogeneous access systems may include a handoff between the following protocols: ultra Mobile Broadband (UMB) and High Rate Packet Data (HRPD); WiMax/HRPD; long Term Evolution (LTE)/HRPD, where the system architecture may implement Internet Protocol (IP) mobility using client mobile IP to actively prepare the mobile station for handoff.

Thus, the inter-system handoff control component 115 can utilize tunneling to exchange handoff settings and execute packets prior to handoff as part of session negotiation between the AT 104 and the target access system 112 in order to reduce interruptions during handoff and alleviate the need for session setup during handoff. The inter-system handoff control component 115 can also transmit communication data packets via the source access system 110, wherein the source access system 110 is not normally engaged during negotiations between the AT 104 and the target access system 112.

The AT 104 initially communicates with the source access system 110, wherein the handover preparation component 154 initiates a handover preparation phase when a predetermined event is triggered, e.g., the source access system 110 can be notified of a request to handover a session to a target access system 112, wherein the target access system 112 employs a different set of procedures/technologies than the source access system 110. The notification can be triggered based on weakening of the pilot signal and/or an announcement from the target access system 112 indicating that the AT 104 has reached the coverage edge of the source access system 110 and can initiate handover preparation. The handover preparation component 154 may also facilitate pre-setting parameters of a Radio Access Network (RAN) associated with the target access system 112, and the like.

In related aspects, the handover preparation component 152 may also provide connection preparation for the target access system 112, which may be initiated based on a trigger at the source access system 110 or at the target access system 112 (e.g., initiated based on a predetermined event related to pilot signal information). The target preparation phase may also include requesting air interface resources by the source access system 110 and allocating radio resources from the target system to the AT. Likewise, the handover performing component 154 enables the AT 104 to obtain the target access system 112 over the air, wherein IP traffic is redirected to the AT 104 and packets are transmitted (e.g., transparently or non-transparently) via the source access system 110. In an aspect, the tunneling may also be cascaded (e.g., a cascaded tunnel existing between the AT and the source core system and between the source system and the target system).

Fig. 2 illustrates a particular aspect in which the handover preparation component 252 implements tunneling from the AT 204 to the source access system 210 in conjunction with another tunnel from the source access system 210 to the target access system 212. These tunnels 275, 279 may represent logical associations (e.g., IP, L2 (data link layer), signaling, etc.) between the AT, the source access system 210, and the target access system. As shown in fig. 2, AT 204 can detect a change in signal strength to initiate a session handoff from source access system 210 to target access system 212. For example, initially, the handover preparation component 252 establishes a tunnel between the source access system 210 and the AT 204. Thus, the source access system 210 can be aware that the AT 204 requests a session handoff to the target access system, wherein the source access system 210 then designates the target access system based on, for example, pilot reports. The handover preparation component 252 then facilitates establishment of another tunnel between the source access system 210 and the target access system 212. For example, the tunnel 279 may be established via a mapping determined in part by the pilots reported by the AT 204 without requiring the AT to have this information.

The system 200 may also include a home agent 202, which may be a router on the home network of the access terminal that maintains information related to routing packets received from the internet 206 to the access terminal 204 during transmission of the packets between the source access system 210 and the target access system 212. For example, home agent 202 may also employ a tunneling mechanism to forward data from the Internet 206, thereby eliminating the need to change the IP address of access terminal 204 each time access terminal 204 connects to the home network from a different location.

Further, in an aspect, the source access system 210 can provide an indication to the target access system 212 and/or the inter-system handover control component 215 that the source access system 210 is no longer serving the access terminal 204 and that the target access system 212 is serving the access terminal 204. In addition, the source access system 210 may indicate the identity of the most recently received data packet, thereby providing the target access system 212 with the next data packet in the sequence.

In another example, the source access system 210 may indicate which data packets the source access system 210 has forwarded to the target access system 212. For example, the source access system 210 may interact to ensure that duplicate data is not delivered to the target access system 212. The target access system 212 may receive data for transmission from the source access system 210 and may also receive a transmission sequence indication so that a seamless handoff occurs and the data is sent to the access terminal 204 in the proper order.

It should be recognized that various substitutions may be conceived and are intended to fall within the scope of the appended claims. For example, the source access system 210 may receive the indication before the target access system 212 receives the indication, i.e., the access terminal 204 is requesting a handoff to the target access system 212. Further, the source access system 210 can accordingly indicate a handoff to the target access system 212 and provide for transmission to the access terminal 204.

Fig. 3 illustrates handover pre-setup/execution and re-routing of data packets between heterogeneous networks, a source access system represented by LTE system 310 and a target access system represented by HRPD system 315. As the AT 304 moves to another geographic location, a session handoff may be initiated based on the pilot report. Alternatively, handover preparation may be triggered due to the advertisement by the target access system 315 of the source access system 310 in terms of ambient technology. This tunnel communication 360 may be established in advance during a handover preparation phase in order to establish a target session, for example. Thus, the system 300 facilitates handoff of a session from a source access system 310 to a target access system 315 during various phases of handoff preparation and handoff execution by enabling tunneling from an AT 304, wherein the AT 304 operates in dual mode for both the source and target access systems.

Fig. 4 illustrates a methodology of handover pre-provisioning/execution and data packet re-routing between heterogeneous networks in accordance with an aspect. While the exemplary method is illustrated and described herein as a series of blocks representative of various events and/or acts, the subject aspects are not limited by the illustrated ordering of such blocks. For example, some acts or events may occur in different orders and/or concurrently with other acts or events, apart from the ordering illustrated herein, in accordance with the described aspects. Moreover, not all illustrated blocks, events or acts, may be required to implement a methodology in accordance with an aspect of the subject matter. Further, it should be appreciated that the exemplary method and other methods according to the described aspects may be implemented in association with the method illustrated and described herein as well as in association with other systems and apparatus not illustrated or described.

Initially AT 410, an AT interacts with and employs a process/technique of a source access system. Subsequently, AT 420, a handover preparation phase is initiated that provides tunneling between the AT and the source and/or target access system in advance to enable packet transmission via the source access system and pre-set session configuration in the target access system.

Next, at 430, a target connection preparation phase occurs, which may be based on a trigger at the source access system or at the target access system, such as occurrence of a predetermined event related to pilot signal information. Thus, the AT may request air interface resources and may also obtain radio resource allocations from the target system. During the handoff completion phase, the AT acquires the target system over the air, AT 440, where the AT then begins communicating directly with the target system AT 450.

Fig. 5 illustrates a related methodology 500 for session handoff in accordance with another aspect of the handoff preparation phase. Initially, at 510, a source access system can be notified of a request to handoff a session to a target access system, where the notification is triggered based on occurrence of one or more predetermined events. For example, the notification may be triggered based on a weakening pilot signal and/or an announcement from the target access system, where the announcement may indicate that the AT has reached the edge of coverage of the source system and/or may wish to prepare for a handoff. Then, at 520, a mapping can be made between the current pilot and the other pilots recorded to designate the target access system. Next, at 530, a tunnel may be established between the source access system and the target access system, wherein parameters of a Radio Access Network (RAN) of the target system may be pre-set at 540 (e.g., tunneling at the data link layer — L2 tunneling).

Fig. 6 illustrates an exemplary block diagram for interaction between a user equipment or access terminal 610, a source access system 640, and a target access system 660. The UE 610 includes a target system protocol 611 and a source system protocol 612 to enable dual mode operation with both systems. In an aspect, the source access system 640 does not participate in a session negotiated between the AT 610 and the target access system 660 (e.g., due to technology differences). Likewise, tunneling encapsulation protocol 615 may provide tunneling prior to handoff as part of session negotiation between AT 610 and target access system 660 (e.g., to reduce interruptions during handoff and alleviate the need to perform session establishment during handoff) while transmitting data packets (transparently or non-transparently) via source access system 640.

The arrangement 600 facilitates handover of a session from a source access system 640 to a target access system 660 with handover preparation and handover execution prior to handover by implementing a tunneling protocol 615 from an AT 610. Likewise, the RAN encapsulation component 645 facilitates handover preparation and presets parameters for the UE 610 to communicate with a Radio Access Network (RAN) associated with the target access system 660.

Fig. 7 illustrates an exemplary call flow 700 for rerouting data packets in heterogeneous networks 704,706. Initially, AT 710, the AT or UE 702 is AT the source network 704, where the AT 702 or UE registers with the home agent 708. At 720, the UE may perform a pre-setup of a session with the target AN 706 during handover preparation. Subsequently, at 740, and during the handover execution phase, the UE receives the resource allocation and obtains the target AN 706. Next, the UE may communicate directly with the target AN and also register with the home agent. At 750, the packet may also be communicated with the target access network.

Fig. 8 illustrates exemplary heterogeneous wireless communication systems 811, 821 that can provide services to a wireless terminal 826. Systems 811, 821 represent a target access system and a source access system, respectively, that include multiple sectors 802, 804, 808 and 806, 810, 812. The target access system 811 and the source access system 821 may employ different wireless services within these sectors. Although in practice the sectors are shown as hexagons and have substantially the same size, it should be understood that the size and shape of the sectors may vary depending on the geographic area, number, size and shape of the physical obstruction (e.g., building), as well as several other factors. Access points (base stations, access routers, etc.) 814, 816, 820 are associated with sectors 802, 804, 808, with technology "a" being used as part thereof. Likewise, access points 818, 822, 824 are associated with sectors 806, 812, 810 using technology "B" as part thereof, where technology "B" is different from technology "a".

Because the wireless terminal 826 is geographically mobile, it may receive a stronger signal from the target access system 811 than from the source access system 821. It is to be appreciated that the wireless terminal 826 can operate in dual mode with the source access system 821 and the target access system 811, wherein the inter-system handoff control component 819 can provide tunneling prior to handoff as part of session negotiation between the AT 826 and the target access system 811. Thus, data packets may be transmitted (transparently or non-transparently) via the source access system 821 while the AT is preparing to handoff to the target system, and then redirected to the target system once handoff is complete.

Fig. 9 illustrates a particular system 900 that facilitates communicating data between heterogeneous access systems via tunneling established by a mobile unit and a target access system via a source access system when a handoff is requested. System 900 can be associated with an access point and can include a group 902 of components that can communicate with each other in connection with communicating data packets to an access terminal during a handoff between heterogeneous access systems. Group 902 includes means 904 for determining that an access terminal has requested a handoff from a first access system to a second access system. This determination may occur, for example, by the source access system analyzing the identity of the target access system. The identification determination may also implement a mapping scenario to specify a target access system.

Group 902 further includes a component 906 for receiving communication data from the first access system and an indication from the first access system of which communication data should next be transmitted to the access terminal. For example, a timestamp or other sequence number in the RLP packet header can indicate which communication data should be sent to the access terminal next. Group 902 also includes a component 908 for receiving communication data from a network module, wherein the data is desired to be transmitted to the access terminal. In addition, the communication data received from the network module may be IP-encapsulated data packets that are associated with sequence numbers or timestamps, thereby enabling the access system to determine which communication data should be sent to the access terminal next. Group 902 can also include means 910 for transmitting communication data to the access terminal in an appropriate order, wherein the communication data is received from the first access system and the network module. For example, the second access system may receive communication data to be transmitted to the access terminal, where the communication data is not repeated with communication data already transmitted by the first access system, and where the communication data is to be transmitted in a particular order. The system 900 may also include a memory 912 that may hold instructions related to the execution of the components 904 and 910. System 900 enables a new or target access system to begin receiving communication data in preparation for handoff even if the source access system has not relinquished control, wherein the received communication data can be buffered in the target access system.

Fig. 10 illustrates a system 1000 that can be employed to transmit data to an access terminal before and after a handoff in layer L2. System 1000 includes a receiver 1002 that receives a signal from, for instance, one or more receive antennas, performs typical actions on (e.g., filters, amplifies, downconverts, etc.) the received signal, and digitizes the conditioned signal to obtain samples. A demodulator 1004 can demodulate and provide received pilot symbols to a processor 1006 for channel estimation.

Processor 1006 can be a processor dedicated to analyzing information received by receiver component 1002 and/or generating information for transmission by a transmitter 1014. Processor 1006 can be a processor that controls one or more portions of system 1000, and/or a processor that analyzes information received by receiver 1002, generates information for transmission by a transmitter 1014, and controls one or more portions of system 1000. System 1000 can include an optimization component 1008 that can optimize performance of a user device before, during, and/or after a handover. Optimization component 1008 may be incorporated into processor 1006. It is to be appreciated that optimization component 1008 can include optimization code that performs a utility-based analysis that involves determining whether to handoff from a source access system to a target access system. The optimization code can utilize artificial intelligence based methods related to making inferences and/or probabilistic determinations and/or statistical-based determinations related to performing handovers.

System (user equipment) 1000 can also include memory 1010 that is operatively coupled to processor 1006 and that can store information such as signal strength information regarding base stations, scheduling information, and the like, wherein such information can be utilized to determine whether and when to request a handoff. Memory 1010 may also store protocols associated with generating look-up tables, etc., such that system 1000 may employ the stored protocols and/or algorithms to increase system capacity. It will be appreciated that the data store (e.g., memories) components described herein can be either volatile memory or nonvolatile memory, or can include both volatile and nonvolatile memory. By way of example, and not limitation, nonvolatile memory can include Read Only Memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), electrically erasable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM), which acts as external cache memory. By way of example and not limitation, RAM is available in many forms such as Synchronous RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), and Direct Rambus RAM (DRRAM). The memory 1010 is intended to comprise, without being limited to, these and any other suitable types of memory. Processor 1006 is coupled to a symbol modulator 1012 and a transmitter 1014, wherein transmitter 1014 transmits the modulated signal.

Fig. 11 illustrates a system that can be employed to receive a handoff indication and/or transmit data to an access terminal accordingly. System 1100 includes a base station 1102 with a receiver 1110 that receives signal(s) from one or more user devices 1104 via one or more receive antennas 1106 and transmits to the one or more user devices 1104 via a plurality of transmit antennas 1108. In one example, receive antennas 1106 and transmit antennas 1108 may be implemented using a single set of antennas. Receiver 1110 can receive information from receive antennas 1106 and is operatively associated with a demodulator 1112, wherein demodulator 1112 demodulates received information. As will be appreciated by those skilled in the art, receiver 1110 may be, for example, a Rake receiver (e.g., a technique that uses multiple baseband correlators to individually process multipath signal components.), an MMSE-based receiver, or some other suitable receiver for separating out the user devices assigned thereto. For example, multiple receivers (e.g., one for each receive antenna) may be employed and the receivers may communicate with each other to provide improved estimates of user data. Demodulated symbols are analyzed by a processor 1114, the processor 1114 being similar to the processor described above with reference to fig. 9 and coupled to a memory 1116, the memory 1116 storing information related to user equipment assignments, look-up tables related thereto, and the like. The receiver output for each antenna can be jointly processed by receiver 1110 and/or processor 1114. A modulator 1118 can multiplex the signal for transmission by a transmitter 1120 through transmit antennas 1108 to user devices 1104.

As used in this application, the term AT refers to a terminal node accessing two access systems, where the terminal node may be: an end user device, a mobile device, a device operating according to the 3GPP2 specification, a device operating according to the 3GPP specification, a device operating according to the IEEE specification, or/and a user equipment.

The various illustrative logics, logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with the following components: a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. Further, at least one processor may comprise one or more modules operable to perform one or more of the above-described steps and/or actions.

Further, the steps and/or actions of a method or algorithm described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. Further, in some aspects, the processor and the storage medium may reside in an ASIC. Further, the ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal. Further, in some aspects, the steps and/or actions of a method or algorithm may reside as one or any combination or set of codes and/or instructions on a machine readable medium and/or computer readable medium, which may be incorporated into a computer program product.

In one or more aspects, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on and transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Further, any connection may be termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

While the foregoing disclosure discusses illustrative aspects and/or embodiments, it should be noted that various changes and modifications could be made herein without departing from the scope of the described aspects and/or embodiments as defined by the appended claims. Furthermore, although elements of the described aspects and/or embodiments may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated. Moreover, all or a portion of any aspect and/or embodiment may be utilized with all or a portion of any other aspect and/or embodiment, unless stated otherwise.

Claims (30)

1. A session handoff method, comprising:

performing tunnel communication between a source access system and a target access system;

transmitting a handover-related signal from an Access Terminal (AT) to the target access system via the tunneling operation and through the source access system.

2. The method of claim 1, further comprising: establishing a tunnel from the AT to the source access system, wherein the source access system or the target access system is capable of operating based on AT least one of a 3GPP specification, a 3GPP2 specification, or an IEEE specification.

3. The method of claim 1, wherein transmitting a signal related to handover further comprises: a session is negotiated between the AT and the target access system to facilitate handing off a communication session of the AT from the source access system to the target access system.

4. The method of claim 1, further comprising: a handover preparation phase is initiated between the AT and the target access system when a predetermined event is triggered.

5. The method of claim 1, further comprising: receiving an advertisement from the target access system indicating that the AT reaches an edge of coverage; and initiating the tunneling based on receiving the advertisement and the sending a handover related signal.

6. The method of claim 1, wherein transmitting a signal related to handover further comprises: pre-setting Radio Access Network (RAN) parameters associated with the target access system.

7. The method of claim 1, further comprising: requesting air interface resources from the target access system to initiate communication between the AT and the target access system.

8. The method of claim 1, further comprising: and registering the AT and the target access system to complete session switching.

9. The method of claim 1, wherein the tunneling is based on a mapping from the source access system to the target access system to facilitate handover preparation of the AT to the target access system.

10. At least one processor configured to provide session handoff, the at least one processor comprising:

a first module for establishing a tunnel between a source access system and a target access system, wherein the source access system comprises a first technology different from a second technology of the target access system;

a second module for sending handover-related packets from the AT to the target access system through the tunnel.

11. A computer program product, comprising:

a computer-readable medium comprising:

a first set of codes for causing a computer to establish a tunnel between a source access system and a target access system, the source access system and the target access system being heterogeneous;

a second set of codes for causing the computer to send packets from an AT to the target access system via the tunnel and through the source access system.

12. An apparatus, comprising:

the system comprises a sending module, a receiving module and a sending module, wherein the sending module is used for sending signals between a heterogeneous source access system and a target access system;

means for transmitting packets from the AT to the target access system via the transmitting means.

13. A session handoff method, comprising:

performing tunnel communication between a target access system and a source access system, wherein the target access system and the source access system realize different technologies;

the target access system receives packets sent by the AT and rerouted through the source access system.

14. The method of claim 13, the tunneling occurring without knowledge of the AT.

15. The method of claim 13, further comprising: a session is negotiated between the AT and the target access system as part of handover preparation.

16. The method of claim 13, further comprising: designating the target access system according to a pilot report.

17. The method of claim 13, further comprising: a handover preparation phase is initiated when a predetermined event is triggered to facilitate communication of the AT with the target access system.

18. The method of claim 13, further comprising: notifying the source access system of the session handoff to initiate handoff preparation.

19. The method of claim 13, further comprising: advertising by the source access system to indicate that the AT reaches the edge of coverage.

20. The method of claim 13, further comprising: the pilot signal received by the source access system is weakened to trigger a session handoff.

21. The method of claim 13, further comprising: requesting air interface resources from the target access system during handover preparation.

22. The method of claim 13, further comprising: and registering the AT and the target access system to complete the switching execution.

23. The method of claim 13, further comprising: mapping from the source access system to the target access system to facilitate handover preparation between the source access system and the target access system.

24. The method of claim 13, the tunneling operation is based on one of an inter-system signaling protocol and target system signaling.

25. A computer-implemented system, comprising:

a wireless access terminal operable in both a target access system and a source access system of a heterogeneous wireless communication system;

an inter-system handover control component for transferring a session from the source access system to the target access system.

26. A system for wireless communication, comprising:

a memory unit that provides instructions for switching between a source access system and a target access system, the source access system and the target access system being heterogeneous;

a processor unit that executes the instructions for L2 layer tunneling to the target access system.

27. A communication system, comprising:

a communication module for transmitting a data packet to an access terminal in a heterogeneous communication system;

means for handing off the access terminal from a source access system to a target access system of the communication module.

28. The communication system of claim 27, further comprising: means for tunneling to the access terminal at a data link layer.

29. The communication system of claim 28, further comprising: means for identifying the target access system.

30. The communication system of claim 27, further comprising: means for preparing a session handoff to the target access system.