HK1141386A

HK1141386A - Apparatus and method of performing a handoff in a communication network

Info

Publication number: HK1141386A
Application number: HK10107621.0A
Authority: HK
Inventors: N‧J‧帕雷克; M‧克拉斯尼安斯基
Original assignee: 高通股份有限公司
Priority date: 2007-03-26
Filing date: 2008-03-26
Publication date: 2010-11-05

Description

Apparatus and method for performing handover in communication network

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

This patent application claims priority from the following provisional applications:

provisional application No.60/908,055, entitled "METHOD CONTROL FUNCTION 2HANDOFF LOW LEVEL DESIGN", filed on 26.5.2007,

provisional application No.60/908,120 entitled "NETWORK FUNCTION HIGHLEVEL DESIGN", filed on 26.5.2007,

priority of provisional application No.60/908,047 entitled "TRANSCIEVER FUNCTIONSOFTWARE HIGH LEVEL DESIGN", filed on 26.5.2007,

these provisional applications have been assigned to the assignee of the present application and are hereby expressly incorporated by reference.

Technical Field

The present disclosure relates generally to wireless communications, and more specifically to apparatus and methods for session handoff between network entities.

Background

In the past few years, wireless communication technology has evolved from analog-driven systems to digital systems. Typically, in conventional analog systems, analog signals are relayed on the forward and reverse links and require a high bandwidth to enable the signals to be transmitted and received while being associated with an appropriate quality. Since the analog signal is continuous in time and space, no status message (e.g., a message indicating receipt or non-receipt of data) is generated. In contrast, packet-switched systems allow analog signals to be converted into data packets and transmitted over physical channels between access terminals and base stations, routers, and the like. In addition, digital data is relayed in its native form (e.g., text, internet data, etc.) through the use of a packet-switched network. Accordingly, digital wireless communication systems are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcast, and so on.

As wireless communication devices are increasingly being deployed to perform services while meeting ever-increasing data demands, wireless network bandwidth and data rates are also increasing. In this way, the wireless access point accumulates a queue of data destined for wireless devices served by the access point. In prior art systems, these data queues are small enough that they can be easily managed without affecting the quality of the connection when a handoff of a wireless device communication session is required from one access point to another. However, in current high data rate networks, the data queue becomes very long if the handover is not performed quickly. Such long data queues negatively impact the delay experienced in an ongoing service and, in services such as voice over IP (VoIP), delay is a very important quality of service (QoS) to consider. Moreover, such large queues would require increased use of the backhaul network in order to successfully transmit data, which negatively impacts network cost since the backhaul network is expensive to use.

Therefore, in such a high data rate system, it becomes very important to perform efficient handover between various entities when performing session handover.

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 of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all embodiments. Its sole purpose is to present some concepts of one or more embodiments in a simplified form as a prelude to the more detailed description that is presented later.

In one aspect, a method of performing session handover in a wireless communication system, comprising: receiving an ordered sequence of data packets from an anchor network function module after establishing a communication session with an access terminal, wherein the communication session is controlled by the anchor network function module, wherein the anchor network function module includes a shadow buffer for storing the ordered sequence of data packets; receiving a handoff request from a target transceiver module during transmission of a segment of the ordered sequence of data packets to the access terminal via the session; determining a sequence marker corresponding to an end of the segment as an end point of the transmission; continuing to complete the transmission until the end of the segment; transmitting a handoff data state for the session to the anchor network function module while continuing to complete the transmission, wherein the handoff data state includes an identifier of the target transceiver module and the sequence marker, wherein the handoff data state is to trigger the anchor network function module to transmit a portion of the ordered sequence of data packets from the shadow buffer to the identified target transceiver module, wherein the portion begins after an end of the segment identified by the sequence marker.

In another aspect, at least one processor configured to perform session handoff in a wireless communication system, includes: a first module for receiving an ordered sequence of data packets from an anchor network function module after establishing a communication session with an access terminal, wherein the communication session is controlled by the anchor network function module, wherein the anchor network function module comprises a shadow buffer for storing the ordered sequence of data packets; a second module for receiving a handoff request from a target transceiver module during transmission of a segment of the ordered sequence of data packets to the access terminal via the session; a third module for determining a sequence marker corresponding to an end of the segment as an end point of the transmission; a fourth module for continuing to complete said transmission until the end of said segment; a fifth module for sending a handoff data state for the session to the anchor network function module while continuing to complete the transmission, wherein the handoff data state includes an identifier of the target transceiver module and the sequence marker, wherein the handoff data state is for triggering the anchor network function module to send a portion of the ordered sequence of data packets from the shadow buffer to the identified target transceiver module, wherein the portion begins after an end of the segment identified by the sequence marker.

In another aspect, a computer program product for session handoff in a wireless communication system, comprising a computer-readable medium comprising: at least one instruction for causing a computer to receive an ordered sequence of data packets from an anchor network function module after establishing a communication session with an access terminal, wherein the communication session is controlled by the anchor network function module, wherein the anchor network function module includes a shadow buffer for storing the ordered sequence of data packets; at least one instruction for causing the computer to receive a handoff request from a target transceiver module during transmission of a segment of the ordered sequence of data packets to the access terminal via the session; at least one instruction for causing the computer to determine a sequence marker corresponding to an end of the segment as an end point of the transmission; at least one instruction for causing the computer to continue to complete the transmission to an end of the segment; at least one instruction for causing the computer to transmit a handoff data state for the session to the anchor network function module while continuing to complete the transmission, wherein the handoff data state includes an identifier of the target transceiver module and the sequence marker, wherein the handoff data state is to trigger the anchor network function module to transmit a portion of the ordered sequence of data packets from the shadow buffer to the identified target transceiver module, wherein the portion begins after an end of the segment identified by the sequence marker.

In another aspect, an access point includes: means for receiving an ordered sequence of data packets from an anchor network function module after establishing a communication session with an access terminal, wherein the communication session is controlled by the anchor network function module, wherein the anchor network function module comprises a shadow buffer for storing the ordered sequence of data packets; means for receiving a handoff request from a target transceiver module during transmission of a segment of the ordered sequence of data packets to the access terminal via the session; means for determining a sequence marker corresponding to an end of the segment as an end point of the transmission; means for continuing to complete the transmission until an end of the segment; means for transmitting a handoff data state for the session to the anchor network function module while continuing to complete the transmission, wherein the handoff data state includes an identifier of the target transceiver module and the sequence marker, wherein the handoff data state is used to trigger the anchor network function module to transmit a portion of the ordered sequence of data packets from the shadow buffer to the identified target transceiver module, wherein the portion begins after the end of the segment identified by the sequence marker.

In another aspect, an access point includes: a memory including a handoff manager module having sequence determination logic; a processor in communication with the memory and configured to execute the handoff manager module; a source transceiver module to receive an ordered sequence of data packets from an anchor network function module after establishing a communication session with an access terminal, wherein the communication session is controlled by the anchor network function module, wherein the anchor network function module includes a shadow buffer to store the ordered sequence of data packets; wherein the source transceiver module is configured to receive a handoff request from a target transceiver module during transmission of a segment of the ordered sequence of data packets to the access terminal via the session; wherein the sequence determination logic is to determine a sequence marker corresponding to an end of the segment as an end point of the transmission; wherein the source transceiver module is configured to continue to complete the transmission until the end of the segment; wherein the source transceiver module is to transmit a handoff data state for the session to the anchor network function module while continuing to complete the transmission, wherein the handoff data state includes an identifier of the target transceiver module and the sequence marker, wherein the handoff data state is to trigger the anchor network function module to transmit a portion of the ordered sequence of data packets from the shadow buffer to the identified target transceiver module, wherein the portion begins after an end of the segment identified by the sequence marker.

In another aspect, a method for session handoff in a wireless communication system, comprising: determining that a condition exists for requesting a handoff of an established communication session from a source transceiver module to a target transceiver module, wherein the determining occurs during receipt of a segment of an ordered sequence of data packets from the source transceiver module; in accordance with the determination, sending a handover request to the target transceiver module, wherein the handover request is to trigger the target transceiver module to receive and queue a portion of the ordered sequence of data packets from a shadow buffer of an anchor network function module during reception of the segment, wherein the portion corresponds to a portion of the ordered sequence that follows the segment; receiving a last transmission corresponding to the segment from the source transceiver module; establishing the communication session with the target transceiver function after receiving the last transmission from the source transceiver module; receiving the portion of the ordered sequence of data packets from the queue from the target transceiver function without significant delay from the target transceiver function under control of the anchor network function after the communication session is established with the target transceiver function.

In another aspect, at least one processor configured to perform session handoff in a wireless communication system, comprises: a first module for determining that a condition exists for requesting a handoff of an established communication session from a source transceiver module to a target transceiver module, wherein the determination occurs during receipt of a segment of an ordered sequence of data packets from the source transceiver module; a second module for sending a handover request to the target transceiver module based on the determination, wherein the handover request is for triggering the target transceiver module to receive and queue a portion of the ordered sequence of data packets from a shadow buffer of an anchor network function module during reception of the segment, wherein the portion corresponds to a portion of the ordered sequence that follows the segment; a third module for receiving a last transmission corresponding to the segment from the source transceiver module; a fourth module for establishing the communication session with the target transceiver function module after receiving the last transmission from the source transceiver module; wherein the third module is further configured to: receiving the portion of the ordered sequence of data packets from the queue from the target transceiver function without significant delay from the target transceiver function under control of the anchor network function after the communication session is established with the target transceiver function.

In another aspect, a computer program product for performing a session handoff in a wireless communication system, comprising a computer-readable medium comprising: at least one instruction for causing a computer to determine that a condition exists for requesting a handoff of an established communication session from a source transceiver module to a target transceiver module, wherein the determination occurs during receipt of a segment of an ordered sequence of data packets from the source transceiver module; at least one instruction for causing the computer to transmit a handover request to the target transceiver module in accordance with the determination, wherein the handover request is for triggering the target transceiver module to receive and queue a portion of the ordered sequence of data packets from a shadow buffer of an anchor network function module during reception of the segment, wherein the portion corresponds to a portion of the ordered sequence that follows the segment; at least one instruction for causing the computer to receive, from the source transceiver module, a last transmission corresponding to the segment; at least one instruction for causing the computer to establish the communication session with the target transceiver function after receiving the last transmission from the source transceiver module; at least one instruction for causing the computer to receive the portion of the ordered sequence of data packets from the queue from the target transceiver function without significant latency from the target transceiver function under control of the anchor network function after the communication session is established with the target transceiver function.

In another aspect, an access terminal includes: means for determining that a condition exists for requesting a handoff of an established communication session from a source transceiver module to a target transceiver module, wherein the determination occurs during receipt of a segment of an ordered sequence of data packets from the source transceiver module; means for sending a handover request to the target transceiver module in accordance with the determination, wherein the handover request is to trigger the target transceiver module to receive and queue a portion of the ordered sequence of data packets from a shadow buffer of an anchor network function module during reception of the segment, wherein the portion corresponds to a portion of the ordered sequence that follows the segment; means for receiving a last transmission corresponding to the segment from the source transceiver module; means for establishing the communication session with the target transceiver function after receiving the last transmission from the source transceiver module; means for receiving the portion of the ordered sequence of data packets from the queue from the target transceiver function without significant delay from the target transceiver function under control of the anchor network function after the communication session is established with the target transceiver function.

In another aspect, an access terminal includes: a memory comprising a handoff manager module having handoff determination logic and handoff request logic; a processor in communication with the memory and configured to execute the handoff manager module; wherein the handover determination logic is operable to determine that a condition exists for requesting a handover of the established communication session from the source transceiver module to the target transceiver module, wherein the determination occurs during reception of a segment of the ordered sequence of data packets from the source transceiver module; wherein the handover request logic is to send a handover request to the target transceiver module in accordance with the determination, wherein the handover request is to trigger the target transceiver module to receive and queue a portion of the ordered sequence of data packets from a shadow buffer of an anchor network function module during reception of the segment, wherein the portion corresponds to a portion of the ordered sequence that follows the segment; a communication module in communication with the memory and the processor and configured to receive a last transmission corresponding to the segment from the source transceiver module; wherein the handoff manager module is to establish a communication session with the target transceiver function module after receiving the last transmission from the source transceiver module; wherein the communication module is further configured to: receiving the portion of the ordered sequence of data packets from the queue from the target transceiver function without significant delay from the target transceiver function under control of the anchor network function after the communication session is established with the target transceiver function.

Another aspect includes a method of performing a session handoff by a network-side system of a wireless communication system, comprising: controlling a communication session between an access terminal and a source transceiver module; transmitting an ordered sequence of data packets destined for the access terminal to the source transceiver module; copying the ordered sequence of data packets into a shadow buffer for storing the ordered sequence of data packets; receiving, by the source transceiver module, a handoff request from a target transceiver module during transmission of a segment of the ordered sequence of data packets to the access terminal via the session; determining, by the source transceiver module, a sequence marker corresponding to an end of the segment as an end point of the transmission; continuing, by the source transceiver module, the transmission to the end of the segment; transmitting, by the source transceiver module, a handoff data state for the session to the anchor network function module while continuing to complete the transmission, wherein the handoff data state comprises an identifier of the target transceiver module and the sequence marker; after receiving the handoff data state, the anchor network function module sending a portion of the ordered sequence of data packets from the shadow buffer to the identified target transceiver module, wherein the portion begins after the end of the segment identified by the sequence marker; the anchor network function module receives packet data originating from the access terminal from the source transceiver module during transmission of the portion of the ordered sequence of data packets.

Another aspect includes a system for performing a session handoff in a wireless communication system, comprising: an anchor network function module having a corresponding shadow buffer, wherein the anchor network function module is configured to control a communication session between an access terminal and a source receiver module, wherein the anchor network function module is configured to transmit an ordered sequence of data packets destined for the access terminal to the source transceiver module, wherein the anchor network function module is further configured to copy the ordered sequence of data packets into the shadow buffer, wherein the shadow buffer is configured to store the ordered sequence of data packets; wherein the source transceiver module is configured to receive a handoff request from a target transceiver module during a transmission of a segment of the ordered sequence of data packets to the access terminal via the session, wherein the source transceiver module is configured to determine a sequence marker corresponding to an end of the segment as an end point of the transmission, and wherein the source transceiver module is configured to cause the source transceiver module to continue to complete the transmission until the end of the segment; wherein the source transceiver module is configured to send a handoff data state of the session to the anchor network function module while continuing to complete the transmission, wherein the handoff data state includes the identifier of the target transceiver module and the sequence marker; wherein the anchor network function module, after receiving the handoff data state, is to send a portion of the ordered sequence of data packets from the shadow buffer to the identified target transceiver module, wherein the portion begins after the sequence marker identifies the end of the segment; wherein the anchor network function module is to receive packet data originating from the access terminal from the source transceiver module during transmission of the portion of the ordered sequence of data packets.

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 various embodiments may be employed and the described embodiments are 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 is a schematic diagram of one aspect of an efficient handoff system;

FIG. 2 is a schematic diagram of one aspect of a computer device implementing one or more components of FIG. 1;

fig. 3 is a schematic diagram of one aspect of the functional modules of the access terminal of fig. 1;

FIG. 4 is a schematic diagram of one aspect of the functional modules of the source access point of FIG. 1;

FIG. 5 is a schematic diagram of one aspect of the functional modules of the anchor point (anchor) access point of FIG. 1;

FIG. 6 is a schematic diagram of one aspect of the functional modules of the target access point of FIG. 1;

FIG. 7 is a call flow diagram of one aspect of a call flow of the system of FIG. 1;

fig. 8 is a flow diagram of one aspect of a method of the source access point of fig. 1;

fig. 9 is a flow diagram of one aspect of a method of the access terminal of fig. 1;

fig. 10 is a flow diagram of one aspect of a method of transmitting status from a source transceiver to a target transceiver.

Detailed Description

Various aspects are described below 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 embodiments. It may be evident, however, that such embodiment(s) may be practiced without these specific details.

As used in this application, the terms "component," "module," and "system" are intended to refer to 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: a process running on a processor, an object, an executable, a thread of execution, a program, and/or a computer. For the sake of example, 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, aspects of the present application are described with respect to 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 Equipment (UE), or user device. 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. Further, the description of various aspects relates to a base station. A base station is used for communicating with wireless terminals and may also be referred to as an access point, a node B, an enhanced base station (eBS), or other terminology.

Furthermore, the term "or" means an inclusive "or" rather than an exclusive "or". That is, unless specified otherwise, or clear from context, "X employs A or B" means any of the natural inclusive permutations. That is, if X uses A, X uses B, or X uses both A and B, "X uses A or B" satisfies any of the above examples. In addition, the articles "a" and "an" as used in this application and the claims should generally 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 systems such as CDMA, FDMA, TDMA, OFDMA, SD-FDMA and the like. 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, and so on. UTRA includes wideband CDMA (W-CDMA) and other various CDMA. Further, cdma2000 covers IS-2000, IS-95 and IS-856 standards. TDMA systems implement wireless technologies such as global system for mobile communications (GSM). OFDMA systems may implement wireless technologies such as evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE802.11(Wi-Fi), IEEE 802.16(WiMAX), IEEE 802.20, Flash-And so on. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). The 3GPP Long Term Evolution (LTE) is an upcoming release of UMTS that employs E-UTRA, which uses 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 will be 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. than those described in connection with the figures and/or may not include all of the devices, components, modules etc. described in connection with the figures. Combinations of these methods may also be used.

Referring to fig. 1, in one aspect, a system 10 for performing efficient handovers in a high data rate network 12 includes a plurality of access points 14, 16, 18 that can potentially be used to communicatively couple an access terminal 20 with the network 12. In particular, access point 16 includes a source transceiver module 22, and a wireless communication session 24 is established between source transceiver module 22 and access terminal 20. In addition, access point 16 is in network communication with access point 14, and access point 14 includes an anchor network function module 26 that controls communication session 24. In particular, anchor network function module 26 manages the establishment and transition of communication session 24 and also acts as an interface between network 12 and an access point having communication session 24 with access terminal 20. In this case, for example, anchor network function module 26 receives data packets from network 12 and orders the data packets, and then sends the resulting ordered sequence of data packets 28 to source transceiver module 22 for transmission to access terminal 20. In addition, the access point 14 includes a shadow buffer 30, such as a fixed-size, circular memory (e.g., first-in-first-out) 30 for storing a copy of the ordered sequence of data packets 28 transmitted to the source transceiver module 22.

Since access terminal 20 is mobile in system 10, access terminal 20 may move to a location where access terminal 20 experiences certain conditions that trigger a handoff of communication session 24 to another access point. For example, access terminal 20 constantly monitors pilot signal strengths of neighboring access points and selects a handoff access point based on the comparison of pilot signal strengths. For example, an access terminal 20 moving in direction 31 towards access point 18 may eventually arrive at a location that triggers a target transceiver module 32 of access point 18 to send a handoff request 34 to source transceiver module 22 of access point 16.

When the source transceiver module 22 receives a handoff request 34 during transmission of a segment of the ordered sequence of data packets 28, the system 10 provides for a number of actions to occur to ensure a relatively fast and efficient handoff that minimizes the latency experienced in the ongoing transmission. In particular, system 10 has source transceiver module 22 complete the ongoing transmission of the segment of the ordered sequence of data packets 28, while, or in parallel with, notifying target transceiver module 32 of the end of the ongoing transmission to be completed by source transceiver module 22, and, in some aspects, also concurrently or in parallel with arranging for new, ordered data packets following the ordered sequence of data packets 28 to be directed to target transceiver module 32 for transmission to access terminal 20 after the handoff.

In particular, upon receiving the handoff request 34, the source transceiver module 22 performs the following actions substantially simultaneously or substantially in parallel: determining a sequence marker 36 corresponding to the end of the currently transmitted segment as the end point of the transmission; continuing to complete the ongoing transmission until the end point of the segment; generating a handoff status data message 38 defining a session status, the message 38 including a sequence tag 36 and a target transceiver module identification 40; while continuing to complete the transmission of the segment, a handoff data status message 38 is sent to anchor network function module 26.

Upon receiving handoff data state message 38, anchor network function module 26 immediately switches any new data packets 42 following data packet ordered sequence 28 for transmission to the identified target transceiver module 32. Further, based on data sequence marker 36, anchor network function module 26 is able to determine the end of the last segment transmitted by source transceiver module 22 in the copy of the ordered sequence of data packets 28 stored in shadow buffer 30 and then transmit the remaining portion 44 of the data packets to the identified target transceiver module 32. Thus, the target transceiver module 32 has been preloaded with data packets of the communication session 24 prior to the actual handoff of the communication session 24.

Furthermore, once the transmission of the segment is complete (and thus the ordered sequence 28 of data packets up to sequence marker 36 has been sent), the source transceiver module 22 sends a handover response 46 to the target transceiver module 32 to formally complete the handover of the communication session 24, thereby saving half the round trip time on the backhaul network 3. For example, the handover response 46 includes session state information such as, but not limited to, one or more of link state, retransmission buffer state, control buffer state. At this point, anchor network function module 26 confirms to both transceiver modules that target transceiver module 32 is now serving access terminal 20 and that anchor network function module 26 continues to control communications even though a handoff has occurred.

Moreover, in another aspect, if the target transceiver module 32 is notified by the access terminal 20 or the target transceiver module 32 finds that a packet or fragment transmitted by the source receiver function module 32 is not received from the retransmission buffer in the handover response 46, the target transceiver function module 32 need not contact the source transceiver module 22 and obtain the packet or fragment from the transmission buffer therein. Alternatively, the target transceiver module 32 may obtain the missing data packets or missing segments from the shadow buffer 30 based on their respective sequence tags, thereby reducing the use of the backhaul network.

Thus, the described architecture contemplates multiple possible layer 2 handoffs from one transceiver module to another corresponding to transceivers at different locations without requiring a layer 3 handoff from one network function module to another network function module to be performed before access terminal 20 has moved a substantial distance or otherwise entered a mobile/dormant state during which a layer 3 handoff may be performed for a period of time during which no data communication is occurring.

The method herein has a number of advantages. For example, one advantage is that there is no need to remember which transceiver module or modules previously serviced. Instead, the method allows to obtain from the network function a data packet that was not sent successfully and needs to be retransmitted. Furthermore, since the network function module includes a shadow buffer for buffering sequenced data packets destined for the serving transceiver module, the method allows for instructing the network function module to send any new data to the new transceiver module at the start of the handoff and immediately before the handoff is complete, while the original transceiver module completes transmission with the access terminal. For example, the ongoing transmission of the segment of the ordered sequence of data packets may be a progressive transmission that addresses error correction by allowing retransmissions. By providing for handoff ahead, the new transceiver module is already having data to send to the access terminal over the forward link when handoff actually occurs.

Further, in some aspects, sequence marker 36 may be a byte-based sequence marker as compared to a packet-based sequence marker. This has the advantage that the byte-based sequence marker 36 enables tracking of partial data packets, thereby even minimizing and eliminating partial packet losses.

Further, it has been found that in some aspects, the switching provided by the apparatus and methods herein occurs over a time period of about 20 milliseconds to about 60 milliseconds; in another aspect, occurs over a time period of about 40 milliseconds to about 80 milliseconds; in other aspects, the time period occurs in less than 100 milliseconds.

The components of system 10 (fig. 1) are shown in fig. 2 as being implemented in a computing device 50, computing device 50 including a memory 50 in communication with a processor 54. The memory 52 is used to store applications that are executed by the processor 54. The memory may include: random Access Memory (RAM), Read Only Memory (ROM), and combinations thereof. In particular, each component of system 10 (FIG. 1) includes one or more functional modules, applications, or programs 62 for performing the component-specific actions described herein. Further, processor 54 is operative to perform processing functions associated with one or more of the components described herein. The processor 54 may comprise a single processor or multiple sets of processors or multi-core processors. Further, the processor 54 may be implemented as an integrated processing system and/or a distributed processing system.

In addition, computing device 50 includes a user interface 56, user interface 56 being used to receive input from access terminal 20 and generate output to be presented to a user. The user interface 56 includes one or more input devices including, but not limited to: a keyboard, a keypad, a mouse, a touch-sensitive display, navigation keys, function keys, a microphone, a voice recognition component, any other device capable of receiving input from a user, or a combination thereof. Further, user interface 56 may include one or more output devices, including but not limited to a display, a speaker, a tactile feedback device, a printer, any other device capable of presenting an output to a user, or a combination thereof.

Further, computing device 50 includes a communication component 58 for establishing and maintaining communications with one or more other components using hardware, software, and services. The communications component 58 performs communications between components on the computing device 50, as well as communications between the computing device 50 and external devices, such as: access points 14, 16, 18 (fig. 1), other network-side or infrastructure elements, or other devices connected serially or locally to computing device 50. The communication component 58 includes a receiver for receiving communications and a transmitter for transmitting communications. Further, the communication component 58 includes respective receive and transmit chain components to enable exchange of messages according to one or more respective protocols.

Further, the computing device 50 also includes a database 60, which database 60 may be any suitable combination of hardware and/or software that provides mass storage for data/information, data relationships, and software programs/applications implemented in connection with the aspects described herein when the active memory 52 is not used. In addition, the database 60 stores one or more functional modules/programs/applications 62 when the corresponding application is not in the active memory 50.

Referring to fig. 3, in one aspect of access terminal 20, functional program 62 (fig. 2) comprises an Access Terminal (AT) handoff manager module 70, terminal (AT) handoff manager module 70 comprising logic, executable instructions, or the like, for performing handoff-related functions described herein. In particular, the AT handoff manager module 70 includes handoff determination logic 72 for evaluating signal strength of various access points and determining when conditions exist for handoff. In addition, AT handoff management module 70 includes handoff request logic 74 that, in response to the output of determination logic 72, informs target transceiver module 32 that a handoff is requested. In addition, AT handoff management module 70 includes handoff resource logic 76 for managing and coordinating handoff resources for communication sessions.

Referring to fig. 4, in one aspect of access point 16, functionality 62 (fig. 2) includes a source Access Point (AP) handoff manager module 80, source Access Point (AP) handoff manager module 80 including logic, executable instructions, or the like, for performing handoff-related functions described herein. In particular, source AP handoff manager module 80 includes sequence determination logic 82, and sequence determination logic 82 is configured to evaluate an ongoing transmission and to find an end point of the transmission, thereby defining it as sequence marker 36 (fig. 1). In addition, source AP handoff management module 80 includes target determination logic 84 to parse handoff request 34 and determine target transceiver module identifier 40. In addition, source AP handoff management module 80 includes completion determination logic 86 to determine when the handoff is complete. In addition, source AP handoff management module 80 is configured to generate and initiate transmission of handoff data status message 38 and handoff response message 46.

Referring to fig. 5, in one aspect of access point 14, feature 62 (fig. 2) includes an anchor AP handoff manager module 90, anchor AP handoff manager module 90 comprising logic, executable instructions, or the like, for performing handoff-related functions described herein. In particular, anchor AP handoff manager module 90 includes control logic 92 to manage the routing of forward link and reverse link communications between network 12 (fig. 1) and one or more other access points that maintain communication sessions with one or more access terminals. In addition, the anchor AP handoff management module 90 includes shading logic 94 for controlling the operation of the shading buffer 30 (FIG. 1) and retrieving data packets from the shading buffer 30. In addition, anchor AP handoff management module 90 includes switching logic 96 for managing the control of changing sessions from one transceiver module to another, including managing the exchange of state information, including buffering. In addition, anchor AP handoff management module 90 includes sequence determination logic 98 that obtains data from shadow buffer 30 in response to a request, including in response to handoff data status message 38 and requesting misaligned data packets.

Referring to fig. 6, in one aspect of access point 18, functional program 62 (fig. 2) includes a target AP handoff manager module 101, target AP handoff manager module 101 including: logic, executable instructions, and the like, for performing the handoff-related functions described herein. Specifically, target AP handoff manager module 90 includes handoff request logic 103 that generates and transmits handoff request message 34 after receiving a handoff request from an access terminal. Further, target AP handoff manager module 90 includes Forward Link (FL) and/or Reverse Link (RL) queues 105, Forward Link (FL) and/or Reverse Link (RL) queues 105 for queuing data packets to or from respective access terminals that are or will be serviced by target AP handoff manager module 90 according to handoff preparation activity. In addition, target AP handoff manager module 90 includes sequence logic 107 for determining how to arrange data held in queues or data received in preparation for handoff, such as data packet portion 44 and/or misaligned data, such as may be found when receiving source transceiver state information after handoff is complete.

Referring to fig. 7, in a non-limiting aspect, call flow 111 details the interaction between various components of a high data rate network, such as system 10 (fig. 1). In this example, Access Terminal (AT)20 has source TF 22, target TF32, and other TF 33, otherwise referred to as an "active set," that communicate with AT 20 as a potential transceiver module. Each transceiver module in the active set receives a unique set index number, so TF 22 is designated as "0" in this example, and TF32 is designated as "1" and TF 33 is designated as "2". In either case, source TF 22 maintains a communication session with AT 20 in act 115, which may also be referred to as maintaining a serving sector, since each TF serves a different sector. AT act 117, AT 20 detects a condition that triggers a handoff, such as a weakening of the pilot signal strength of source TF 22 and/or an intensification of the pilot signal strength of target TF 32. AT 20 identifies which sector (member of the active set) it is to handoff to, and sends a change control request identifying the desired serving sector to all transceiver modules in the active set in acts 119, 121 and 123 in order to effect the handoff. In acts 125 and 127, source TF 22 and target TF32 detect that they are the TF involved in the desired handoff. In response, target TF32 sends a handoff request to source TF 22 in act 129. In response, source TF 22 sends a handoff data status message to network function module 26 (or more specifically to its control module portion, referred to as anchor network control function 27) at act 131. As described above, the handoff data state message identifies target TF32 as the TF that received the session, and the sequence marker identifies where source TF 22 will stop sending data.

In this regard, it should be noted that in some aspects, such as in Ultra Mobile Broadband (UMB) implementations, an access point may be divided into a number of different entities, that is: a Network Control Function (NCF); a Network Data Function (NDF); a Transceiver Function (TF). In general, the NCF may initiate session and connection layer signaling protocols, for example, to transfer control of a session from one TF to another TF. For example, these actions include: managing access to a system from an Access Terminal (AT); provide session discovery/creation/termination functions, allocate/reclaim dedicated resources for connections, and the like. As noted above, the Transceiver Function (TF) also represents a sector that performs functions related to the Medium Access Control (MAC) layer (e.g., to provide an air interface attachment point for access terminals in its sector). In addition, a Network Data Function (NDF) can implement data processing functions to relay data between the network and the transceiver function serving the access terminal. Furthermore, the ability of the NDF to route data packets is controlled by the NCF, which specifies the relationship between the terminal and the transceiver function associated with the handover. Thus, for forward link traffic from the network to the access terminal, the NDF can manage shadow buffers and apply Virtual Radio Link Protocol (VRLP) sequencing, etc., and perform corresponding functions for reverse link traffic from the access terminal to the network.

Returning to the call flow, after receiving the handoff data state message at act 131, anchor NCF 27 is operable to generate a handoff switch command at act 133 and send the command to NDF 29. The handoff switch command identifies the AT, the target TF, the corresponding MAC identifier and the sequence tag from the handoff data state message. Anchor NCF 27 maintains the reverse link connection from AT 20 through source TF 22 to anchor NDF 29 until the handoff is completed AT act 135, and anchor NCF 27 directs any forward link data packets following the sequence marker to be sent to target TF32 AT acts 137 and 139, where they will be queued for delivery to AT 20 after handoff. In act 141, source TF 22 completes the transfer. In one aspect, for example, the completion includes performing a last error correction retransmission, such as a hybrid automatic repeat request (HARQ) transmission corresponding to the last data segment that it will transmit as indicated by source TF 22. Accordingly, in act 145, source TF 22 sends a handoff response message to target TF32 to confirm the handoff. The handover response message includes final state information including one or more of final information on which sequences have been transmitted, information on retransmission buffering, information on control buffering, and information on reverse link buffer level.

Further, exemplary states to transmit include: data state, connection state, session state, and the like. Data state refers to the state of the access network in the data path between the access terminal and the network data function during connection and/or handoff transitions. Such data states also include entries such as: header compressor state or radio link protocol buffer state, which are typically dynamic in nature. Likewise, the connection state indicates the state in the access network on the control path between the access terminal and the NCF (which is not saved when the connection is closed and the access terminal is still idle). The connection status also includes information such as: a set of air interface resources reserved for the access terminal, power control loop values, active set information, and the like.

Thus, target TF32 now has all the information it needs to collect about the communication session when source TF 22 is away. Further, after sending the handoff response, source TF 22 acknowledges the handoff to anchor NCF 27 in act 145 by sending a handoff transfer message that includes target TF32 and the target TF active set index. AT the same time, target TF32 sends one or more resource messages for establishing communication with AT 20 and controlling the session, in act 147. Upon receiving the handoff transfer message from source TF 22, NCF 27 sends a handoff completion message to all TFs in the active set in acts 151, 153 and 155, where the handoff completion message identifies the serving TF, i.e., target TF 32. Thus, call flow 111 defines a level 2handoff detection and handoff that operates efficiently, reducing latency of high data rate networks. For example, in one aspect, call flow 11 may reduce latency in networks such as: a High Speed Data System (HSDS) network having a data rate greater than about 1 mbit/sec, or in another aspect, greater than about 5 mbit/sec, and in another aspect, a data rate in a range from about 10 mbit/sec to about 150 mbit/sec. In addition, the structure of call flow 111 places the RLP functionality close to AT 20, as compared to having it deep into the network, with the goal of further reducing latency.

The method of operation of the system is described below. While the exemplary method is illustrated and described as a series of blocks representative of various events and/or acts, the described aspects are not limited by the order of the blocks. For example, some acts or events may occur in different orders and/or concurrently with other acts from that shown and described 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 aspects herein. Moreover, it will be appreciated that the exemplary method and other methods according to the aspects described herein may be implemented in accordance with the method illustrated and described herein, as well as in accordance with other systems and methods not illustrated or described.

Referring to fig. 8, in operation, in one aspect, a method 160 of session handoff in a wireless communication system includes: after establishing a communication session with an access terminal, an ordered sequence of data packets is received from an anchor network function module. In this case, the communication session is controlled by the anchor network function module, wherein the anchor network function module includes a shadow buffer for storing the ordered sequence of data packets (block 162). For example, an ordered sequence of data packets is received on the forward link from a network data control function.

Further, the method comprises: during transmission of a segment of the ordered sequence of data packets to the access terminal via the session, a handoff request is received from the target transceiver module (block 164). For example, the target transceiver module has received a request from the access terminal to initiate a handoff.

Further, the method comprises: a sequence marker corresponding to the end of the segment is determined as the end point of the transmission (block 166). For example, the source transceiver module is used to determine the end of its currently transmitted segment, which may be a progressive transmission, such as may be found in an error correction transmission that allows for repeated transmissions.

Further, the method comprises: the transmission continues to be completed until the end of the segment (block 168). It can be seen that the transmission can be an error correction type transmission, such as a hybrid ARQ transmission.

Further, the method comprises: concurrently with continuing to complete the transmission, the handoff data state of the session is transmitted to the anchor network function module. In this case, the handoff data state includes the identifier and sequence tag of the target transceiver module. Further, the handoff data state is used to trigger the anchor network function module to send a portion of the ordered sequence of data packets from the shadow buffer to the identified target transceiver module, where the portion begins after the end of the segment identified by the sequence marker (block 170). For example, the source transceiver module may be operative to forward the handoff data state to a network control function module operative to transition control to the target transceiver module such that the transmission portion of the shadow buffer following the end of the segment can be queued at the target transceiver module prior to handoff. Allowing such preloading of the target transceiver module while the source transceiver module completes its transmission is efficient and provides low latency handoff, especially in high data rate networks.

Referring to fig. 9, in another aspect, a method 180 of performing a session handoff in a wireless communication system includes: it is determined that a condition exists that requests a handoff of an established communication session from a source transceiver module to a target transceiver module, wherein the determination occurs during receipt of a segment of the ordered sequence of data packets from the source transceiver module (block 182). For example, an access terminal includes logic to detect a handoff condition based on received pilot signal strengths of neighboring access points.

The method further comprises the following steps: in accordance with the determination, a handover request is sent to the target transceiver module, where the handover request is used to trigger the target transceiver module to receive and queue a portion of the ordered sequence of data packets from the shadow buffer of the anchor network function module during reception of the segment, where the portion corresponds to a portion of the ordered sequence following the segment (block 184). For example, the sending of a handoff request by the access terminal results in a series of actions whereby the source transceiver module is notified of the handoff request and provides state information prior to handoff in order to allow the target transceiver module to build a queue of data packets beyond the end of the segment currently being transmitted by the source transceiver function.

Further, the method comprises: a last transmission corresponding to the segment is received from the source transceiver module (block 186). For example, the transmission may be an error correction transmission comprising a given number of retransmissions. The situation occurs where time is wasted in performing the error correction function if the handoff is implemented immediately, and aspects of the present invention take full advantage of this time to complete the transmission by pre-provisioning the target transceiver with data, so that the latency of the handoff is reduced.

Further, the method comprises: after receiving the last transmission from the source transceiver module, a communication session is established with the target transceiver function (block 188). For example, once the last transmission is completed, the communication session of the access terminal is handed off to the target transceiver module.

Further, the present invention includes: a portion of the ordered sequence of data packets from the queue is received from the target transceiver function without significant delay after establishing the communication session with the target transceiver function under control of the anchor network function module (block 190). As described above, the anchor network function has previously begun loading any sequencing data following the end of the identified segment into the target transceiver module. Thus, the target transceiver module is able to achieve efficient, low-latency handoff, especially in high data rate systems that are built with large queues and require expensive use of the backhaul network.

Fig. 10 illustrates a related methodology of transmitting status from a source transceiver to a target transceiver in accordance with an aspect. AT 410, the AT establishes an active set by including AT least one sector in the active set. Further, as part of establishing the active set, the AT sends an expectation to the AP that AT least one sector is to be included in the active set. At 420, the AP communicates with the desired sector in preparation for joining the desired sector to the active set. Specifically, if the desired sector agrees to join the active set, the desired sector allocates resources in preparation for communication with the AT. On the other hand, the intended AT may not respond or deny the request. In either case, the AP informs the AT of the result of the view to add the desired sector to the active set AT 430. Subsequently, AT 440, a change in the wireless connection is detected by the AT, which can prompt a change between sectors in the active set. For example, as described above, the handover may occur in layer 2, which is also referred to as the data/radio link layer in a multi-layer protocol. Thus, at 450, the session state is then sent from the source transceiver function to the target transceiver function. Since the sectors in the active set are ready to receive a handoff of a communication session that includes an AT, TF transitions (e.g., radio link protocol in a transceiver function) can be performed seamlessly with very low latency and very fast (e.g., in the range of 20-40 milliseconds).

As used in this application, the terms "component," "system," and the like are intended to refer to a computer-related entity, either hardware, a combination of hardware and software, software in execution, and/or electro-mechanical elements. For example, a component may be, but is not limited to: a process running on a processor, an object, an instance, an executable, a thread of execution, a program, and/or a computer. By way of example, both an application running on a computer and the computer 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.

The word "exemplary" is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects or designs. Also, the examples provided herein are for clarity and understanding only and are not intended to limit the aspects or portions described herein in any way. It can be seen that a variety of additional or alternative examples may be presented, but they have been omitted for the sake of brevity.

Furthermore, all or portions of the various aspects described herein may be implemented as a system, method, apparatus, or article of manufacture using standard programming and/or engineering techniques to provide software, firmware, hardware, or any combination thereof to control a computer to implement the aspects described herein. For example, computer-readable media include, but are not limited to: magnetic storage devices (e.g., hard disk, floppy disk, magnetic tape, etc.), optical disks (e.g., (compact disk) CD, (digital versatile disk) DVD, etc.), smart cards, and flash memory devices (e.g., card, stick, key drive, etc.). Further, it is recognized that a carrier wave can be employed to carry computer-readable electronic data such as those used in transmitting and receiving electronic mail or in accessing a network such as the Internet or a Local Area Network (LAN). Of course, those skilled in the art will recognize many modifications may be made to this configuration without departing from the spirit or scope of the claimed subject matter.

When implemented in software, firmware, middleware or microcode, the program code or code segments to perform the necessary tasks may be stored in a machine-readable medium such as a storage medium. A code segment may be represented by a procedure, a functional block, a subroutine, a program, a routine, a subroutine, a module, a software package, a class, any combination of instructions, a data structure, or a program statement. A code segment may be coupled to another code segment or a hardware circuit by passing and/or receiving information, data, arguments, parameters, or memory contents. Information, arguments, parameters, data, etc. may be passed, forwarded, or transmitted via any suitable means including memory sharing, message passing, token passing, network transmission, etc.

For a software implementation, the techniques described herein may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in memory units and executed by processors. The memory unit may be implemented within the processor or external to the processor, in which case it can be communicatively coupled to the processor via various means.

The above description includes a number of exemplifications of the invention. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the subject matter described in this application is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term "includes" is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in a claim.

Claims

1. A method of performing session handoff in a wireless communication system, comprising:

receiving an ordered sequence of data packets from an anchor network function module after establishing a communication session with an access terminal, wherein the communication session is controlled by the anchor network function module, wherein the anchor network function module includes a shadow buffer for storing the ordered sequence of data packets;

receiving a handoff request from a target transceiver module during transmission of a segment of the ordered sequence of data packets to the access terminal via the session;

determining a sequence marker corresponding to an end of the segment as an end point of the transmission;

continuing to complete the transmission until the end of the segment;

transmitting a handoff data state for the session to the anchor network function module while continuing to complete the transmission, wherein the handoff data state includes an identifier of the target transceiver module and the sequence marker, wherein the handoff data state is to trigger the anchor network function module to transmit a portion of the ordered sequence of data packets from the shadow buffer to the identified target transceiver module, wherein the portion begins after an end of the segment identified by the sequence marker.

2. The method of claim 1, wherein continuing to complete the transmission further comprises:

and sending an error correction message.

3. The method of claim 1, wherein continuing to complete the transmission further comprises:

transmitting a hybrid automatic repeat request (HARQ) message.

4. The method of claim 1, wherein the anchor network function module maintains control of the session while the handover occurs.

5. The method of claim 1, wherein the transmitting comprises:

a data rate greater than about 1 mbit/sec.

6. The method of claim 1, further comprising:

transmitting a handover response message to the target transceiver module, wherein the handover response message includes final state information,

sending a handover transfer message to a network control function portion of the anchor network function module to complete the handover, wherein the anchor control function portion maintains control of the session.

7. At least one processor configured to perform session handoff in a wireless communication system, comprising:

a first module for receiving an ordered sequence of data packets from an anchor network function module after establishing a communication session with an access terminal, wherein the communication session is controlled by the anchor network function module, wherein the anchor network function module comprises a shadow buffer for storing the ordered sequence of data packets;

a second module for receiving a handoff request from a target transceiver module during transmission of a segment of the ordered sequence of data packets to the access terminal via the session;

a third module for determining a sequence marker corresponding to an end of the segment as an end point of the transmission;

a fourth module for continuing to complete said transmission until the end of said segment;

a fifth module for sending a handoff data state for the session to the anchor network function module while continuing to complete the transmission, wherein the handoff data state includes an identifier of the target transceiver module and the sequence marker, wherein the handoff data state is for triggering the anchor network function module to send a portion of the ordered sequence of data packets from the shadow buffer to the identified target transceiver module, wherein the portion begins after an end of the segment identified by the sequence marker.

8. A computer program product for session handoff in a wireless communication system, comprising:

a computer-readable medium comprising:

at least one instruction for causing a computer to receive an ordered sequence of data packets from an anchor network function module after establishing a communication session with an access terminal, wherein the communication session is controlled by the anchor network function module, wherein the anchor network function module includes a shadow buffer for storing the ordered sequence of data packets;

at least one instruction for causing the computer to receive a handoff request from a target transceiver module during transmission of a segment of the ordered sequence of data packets to the access terminal via the session;

at least one instruction for causing the computer to determine a sequence marker corresponding to an end of the segment as an end point of the transmission;

at least one instruction for causing the computer to continue to complete the transmission to an end of the segment;

at least one instruction for causing the computer to transmit a handoff data state for the session to the anchor network function module while continuing to complete the transmission, wherein the handoff data state includes an identifier of the target transceiver module and the sequence marker, wherein the handoff data state is to trigger the anchor network function module to transmit a portion of the ordered sequence of data packets from the shadow buffer to the identified target transceiver module, wherein the portion begins after an end of the segment identified by the sequence marker.

9. An access point, comprising:

means for receiving an ordered sequence of data packets from an anchor network function module after establishing a communication session with an access terminal, wherein the communication session is controlled by the anchor network function module, wherein the anchor network function module comprises a shadow buffer for storing the ordered sequence of data packets;

means for receiving a handoff request from a target transceiver module during transmission of a segment of the ordered sequence of data packets to the access terminal via the session;

means for determining a sequence marker corresponding to an end of the segment as an end point of the transmission;

means for continuing to complete the transmission until an end of the segment;

means for transmitting a handoff data state for the session to the anchor network function module while continuing to complete the transmission, wherein the handoff data state includes an identifier of the target transceiver module and the sequence marker, wherein the handoff data state is used to trigger the anchor network function module to transmit a portion of the ordered sequence of data packets from the shadow buffer to the identified target transceiver module, wherein the portion begins after the end of the segment identified by the sequence marker.

10. An access point, comprising:

a memory including a handoff manager module having sequence determination logic;

a processor in communication with the memory and configured to execute the handoff manager module;

a source transceiver module to receive an ordered sequence of data packets from an anchor network function module after establishing a communication session with an access terminal, wherein the communication session is controlled by the anchor network function module, wherein the anchor network function module includes a shadow buffer to store the ordered sequence of data packets;

wherein the source transceiver module is configured to receive a handoff request from a target transceiver module during transmission of a segment of the ordered sequence of data packets to the access terminal via the session;

wherein the sequence determination logic is to determine a sequence marker corresponding to an end of the segment as an end point of the transmission;

wherein the source transceiver module is configured to continue to complete the transmission until the end of the segment;

wherein the source transceiver module is to transmit a handoff data state for the session to the anchor network function module while continuing to complete the transmission, wherein the handoff data state includes an identifier of the target transceiver module and the sequence marker, wherein the handoff data state is to trigger the anchor network function module to transmit a portion of the ordered sequence of data packets from the shadow buffer to the identified target transceiver module, wherein the portion begins after an end of the segment identified by the sequence marker.

11. The access point of claim 10, wherein the transmission further comprises:

and correcting the error message.

12. The access point of claim 10, wherein the transmission further comprises:

hybrid automatic repeat request (HARQ) messages.

13. The access point of claim 10, wherein the anchor network function module maintains control of the session while the handoff occurs.

14. The access point of claim 10, wherein the transmission comprises:

a data rate greater than about 1 mbit/sec.

15. The access point of claim 10, wherein the source transceiver module is to:

sending a handover switch message to a network control function portion of the anchor network function module to complete the handover, wherein the anchor control function portion maintains control of the session.

16. A method for session handoff in a wireless communication system, comprising:

determining that a condition exists for requesting a handoff of an established communication session from a source transceiver module to a target transceiver module, wherein the determining occurs during receipt of a segment of an ordered sequence of data packets from the source transceiver module;

in accordance with the determination, sending a handover request to the target transceiver module, wherein the handover request is to trigger the target transceiver module to receive and queue a portion of the ordered sequence of data packets from a shadow buffer of an anchor network function module during reception of the segment, wherein the portion corresponds to a portion of the ordered sequence that follows the segment;

receiving a last transmission corresponding to the segment from the source transceiver module;

establishing a communication session with the target transceiver function after receiving the last transmission from the source transceiver module;

receiving the portion of the ordered sequence of data packets from the queue from the target transceiver function without significant delay from the target transceiver function under control of the anchor network function after the communication session is established with the target transceiver function.

17. The method of claim 16, wherein receiving the segment further comprises:

an error correction message is received.

18. The method of claim 16, wherein receiving the segment further comprises:

a hybrid automatic repeat request (HARQ) message is received.

19. The method of claim 16, wherein the anchor network function module maintains control of the session while the handover occurs.

20. The method of claim 16, wherein the transmitting comprises:

a data rate greater than about 1 mbit/sec.

21. At least one processor that performs session handoff in a wireless communication system, comprising:

a first module for determining that a condition exists for requesting a handoff of an established communication session from a source transceiver module to a target transceiver module, wherein the determination occurs during receipt of a segment of an ordered sequence of data packets from the source transceiver module;

a second module for sending a handover request to the target transceiver module based on the determination, wherein the handover request is for triggering the target transceiver module to receive and queue a portion of the ordered sequence of data packets from a shadow buffer of an anchor network function module during reception of the segment, wherein the portion corresponds to a portion of the ordered sequence that follows the segment;

a third module for receiving a last transmission corresponding to the segment from the source transceiver module;

a fourth module for establishing a communication session with the target transceiver function module after receiving the last transmission from the source transceiver module;

wherein the third module is further configured to: receiving the portion of the ordered sequence of data packets from the queue from the target transceiver function without significant delay from the target transceiver function under control of the anchor network function after the communication session is established with the target transceiver function.

22. A computer program product for performing a session handoff in a wireless communication system, comprising:

a computer-readable medium comprising:

at least one instruction for causing a computer to determine that a condition exists for requesting a handoff of an established communication session from a source transceiver module to a target transceiver module, wherein the determination occurs during a reception of a segment of an ordered sequence of data packets from the source transceiver module;

at least one instruction for causing the computer to transmit a handover request to the target transceiver module in accordance with the determination, wherein the handover request is for triggering the target transceiver module to receive and queue a portion of the ordered sequence of data packets from a shadow buffer of an anchor network function module during reception of the segment, wherein the portion corresponds to a portion of the ordered sequence that follows the segment;

at least one instruction for causing the computer to receive, from the source transceiver module, a last transmission corresponding to the segment;

at least one instruction for causing the computer to establish a communication session with the target transceiver function after receiving the last transmission from the source transceiver module;

at least one instruction for causing the computer to receive the portion of the ordered sequence of data packets from the queue from the target transceiver function without significant latency from the target transceiver function under control of the anchor network function after the communication session is established with the target transceiver function.

23. An access terminal, comprising:

means for determining that a condition exists for requesting a handoff of an established communication session from a source transceiver module to a target transceiver module, wherein the determination occurs during receipt of a segment of an ordered sequence of data packets from the source transceiver module;

means for sending a handover request to the target transceiver module in accordance with the determination, wherein the handover request is to trigger the target transceiver module to receive and queue a portion of the ordered sequence of data packets from a shadow buffer of an anchor network function module during reception of the segment, wherein the portion corresponds to a portion of the ordered sequence that follows the segment;

means for receiving a last transmission corresponding to the segment from the source transceiver module;

means for establishing the communication session with the target transceiver function after receiving the last transmission from the source transceiver module;

means for receiving the portion of the ordered sequence of data packets from the queue from the target transceiver function without significant delay from the target transceiver function under control of the anchor network function after the communication session is established with the target transceiver function.

24. An access terminal, comprising:

a memory comprising a handoff manager module having handoff determination logic and handoff request logic;

wherein the handover determination logic is operable to determine that a condition exists for requesting a handover of the established communication session from the source transceiver module to the target transceiver module, wherein the determination occurs during reception of a segment of the ordered sequence of data packets from the source transceiver module;

wherein the handover request logic is to send a handover request to the target transceiver module in accordance with the determination, wherein the handover request is to trigger the target transceiver module to receive and queue a portion of the ordered sequence of data packets from a shadow buffer of an anchor network function module during reception of the segment, wherein the portion corresponds to a portion of the ordered sequence that follows the segment;

a communication module in communication with the memory and the processor and configured to receive a last transmission corresponding to the segment from the source transceiver module;

wherein the handoff manager module is to establish a communication session with the target transceiver function module after receiving the last transmission from the source transceiver module;

wherein the communication module is further configured to: receiving the portion of the ordered sequence of data packets from the queue from the target transceiver function without significant delay from the target transceiver function under control of the anchor network function after the communication session is established with the target transceiver function.

25. The access terminal of claim 24, wherein the segment further comprises:

and correcting the error message.

26. The access terminal of claim 24, wherein the segment further comprises:

hybrid automatic repeat request (HARQ) messages.

27. The access terminal of claim 24 wherein the anchor network function module maintains control of the session while the handoff occurs.

28. The access terminal of claim 24, wherein the transmission comprises:

a data rate greater than about 1 mbit/sec.

29. A method of performing a session handoff by a network-side system of a wireless communication system, comprising:

controlling a communication session between an access terminal and a source transceiver module;

transmitting an ordered sequence of data packets destined for the access terminal to the source transceiver module;

copying the ordered sequence of data packets into a shadow buffer for storing the ordered sequence of data packets;

during transmission of a segment of the ordered sequence of data packets to the access terminal via the session, the source transceiver module receiving a handoff request from a target transceiver module;

the source transceiver module determining a sequence marker corresponding to an end of the segment as an end point of the transmission;

the source transceiver module continues to complete the transmission until the end of the segment;

while continuing to complete the transmission, the source transceiver module sending a handoff data state for the session to the anchor network function module, wherein the handoff data state includes the identifier of the target transceiver module and the sequence marker;

after receiving the handoff data state, the anchor network function module sending a portion of the ordered sequence of data packets from the shadow buffer to the identified target transceiver module, wherein the portion begins after the end of the segment identified by the sequence marker;

the anchor network function module receives packet data originating from the access terminal from the source transceiver module during transmission of the portion of the ordered sequence of data packets.

30. The method of claim 29, wherein the sequence marker enables tracking of partial data packets.

31. A system for performing session handoff in a wireless communication system, comprising:

an anchor network function module having a corresponding shadow buffer, wherein the anchor network function module is configured to control a communication session between an access terminal and a source receiver module, wherein the anchor network function module is configured to transmit an ordered sequence of data packets destined for the access terminal to the source transceiver module, wherein the anchor network function module is further configured to copy the ordered sequence of data packets into the shadow buffer, wherein the shadow buffer is configured to store the ordered sequence of data packets;

wherein the source transceiver module is configured to receive a handover request from a target transceiver module during a transmission of a segment of the ordered sequence of data packets to the access terminal via the session, wherein the source transceiver module is configured to determine a sequence marker corresponding to an end of the segment as an end point of the transmission, and wherein the source transceiver module is configured to cause the source transceiver module to continue to complete the transmission until the end of the segment;

wherein the source transceiver module is configured to send a handoff data state of the session to the anchor network function module while continuing to complete the transmission, wherein the handoff data state includes the identifier of the target transceiver module and the sequence marker;

wherein the anchor network function module, after receiving the handoff data state, is to send a portion of the ordered sequence of data packets from the shadow buffer to the identified target transceiver module, wherein the portion begins after the sequence marker identifies the end of the segment;

wherein the anchor network function module is to receive packet data originating from the access terminal from the source transceiver module during transmission of the portion of the ordered sequence of data packets.

32. The system of claim 31, wherein the sequence marker enables tracking of partial data packets.