HK1194893B - Delivery of handover command - Google Patents

Description

Switching command delivery

This application is a divisional application of the Chinese patent application with application date of June 19, 2008, application number 200880020771.X, and invention name “Delivery of Switching Command”.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application Serial No. 60/945,070, filed June 19, 2007, and entitled "A METHOD AND APPARATUS DELIVERY OF HANDOVER COMMAND," which is hereby incorporated by reference in its entirety.

Background Art

Wireless communication systems are widely deployed to provide various types of communication, such as voice, data, and video. These systems may be multiple-access systems capable of supporting communication with multiple user terminals by sharing available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, 3GPP long term evolution (LTE) systems, and orthogonal frequency division multiple access (OFDMA) systems. Typically, a wireless communication system includes several base stations, each of which communicates with mobile stations using a forward link, and each mobile station (or access terminal) communicates with the base station using a reverse link.

Generally speaking, a wireless multiple-access communication system is capable of supporting communication for multiple wireless terminals simultaneously. Each terminal communicates with one or more base stations via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from the base station to the terminal, while the reverse link (or uplink) refers to the communication link from the terminal to the base station. This communication link can be established using single-input single-output (SISO), multiple-input single-output (MISO), or multiple-input multiple-output (MIMO) systems.

A MIMO system employs multiple ( _NT ) transmit antennas and multiple ( _NR ) receive antennas for data transmission. The MIMO channel formed by the _NT transmit and _NR receive antennas can be decomposed into _NS independent channels, also known as spatial channels, where _NS ≤ min{ _NT , _NR }. Each of the _NS independent channels corresponds to a dimension. A MIMO system can provide improved performance (e.g., higher throughput and/or better reliability) by utilizing the additional dimensions created by the multiple transmit and receive antennas.

MIMO systems support both time division duplex (TDD) and frequency division duplex (FDD) systems. In a TDD system, forward and reverse link transmissions are in the same frequency region so that the reciprocity principle allows the forward link channel to be estimated based on the reverse link channel. This enables the eNB (evolved Node B) to extract transmit beamforming gain on the forward link when multiple antennas are available at the eNB.

A UE requires an eNB to serve the cell in which it is currently located to facilitate communication. However, as the UE moves away from its current location, it may enter the coverage area associated with another eNB that can better serve the UE. This requires the UE to perform a handover from the current serving eNB to the new eNB. However, to provide reliable communication, the signaling between the UE and the eNB needs to be optimized.

Summary of the Invention

The following is a brief overview of the claimed subject matter to provide a basic understanding of some aspects of the claimed subject matter. This overview is not a comprehensive overview of the claimed subject matter. It is not intended to identify key or important elements of the claimed subject matter, nor is it intended to delineate the scope of the claimed subject matter. Its purpose is simply to present some concepts of the claimed subject matter in a simplified form as a prelude to the more detailed description presented later.

According to this aspect, a method for performing a handover within a wireless communication system is disclosed. A serving eNB receives a measurement report including a current configuration associated with a UE. In response, it transmits a delta configuration including one or more changes to the current UE configuration to facilitate the handover. If the handover is an inter-eNB handover from a source eNB (enhanced Node B) to a different target eNB, a measurement report is sent from the UE to the source eNB, including information about a preferred target eNB. The source eNB forwards the current UE configuration to the preferred target eNB. In response, the target eNB generates a delta configuration with the changes and sends it to the source eNB in a transparent container. The source eNB forwards the transparent container to the UE without knowledge of the information contained in the container. Another aspect relates to the handover being an intra-eNB handover. In this case, the handover message sent to the UE to facilitate the handover includes a selection between a local configuration and a transparent container.

Another aspect relates to determining, based on measurement reports, whether one or more of critical information or non-critical information associated with a handover can be forwarded to a UE. According to this aspect, a source eNB determines whether one or more of the critical information or non-critical information can be sent to the UE, and based at least on the determination, receives appropriate information from a target eNB that is subsequently forwarded to the UE. Based on one or more of the radio conditions associated with the UE obtained from the measurement reports or from the source eNB, only the critical information may be forwarded to the UE. In this case, either the source eNB notifies the target eNB that only the critical information is forwarded, or the UE transmits the information received from the source eNB to the target eNB after the handover is completed.

Another aspect relates to an apparatus for facilitating handover within a communication system. The apparatus includes a receiver that receives at least one measurement report including information about a current configuration of a UE for which a handover is desired. The apparatus also includes a processor that generates at least one handover message including a delta configuration for the UE and provides the message to a transmitter that sends the message to the UE, wherein the delta configuration indicates one or more changes to the current UE configuration required to facilitate the handover.

Another aspect relates to a computer program product comprising a computer-readable medium comprising: code for causing at least one computer to receive a measurement report comprising a current configuration associated with a UE; code for causing the at least one computer to receive a delta configuration comprising one or more changes to the current UE configuration; and code for causing the at least one computer to send the delta configuration to the UE to facilitate handover of the UE. The code facilitates receiving the measurement report comprising the current UE configuration from the UE. In response, the code further facilitates sending the delta configuration comprising one or more changes to the current UE configuration to the UE, thereby enabling the UE to perform a handover. In an inter-eNB handover, the instructions further facilitate forwarding a transparent container comprising the delta configuration to the UE without decoding the contents of the container.

Another aspect relates to a system for facilitating handover. The system includes a receiving module configured to receive one or more measurement reports from one or more UEs, the measurement reports detailing a current configuration associated with the UEs. The system also includes an analyzing module configured to analyze the measurement reports to determine at least one UE requesting a handover. A sending module included within the system sends a message including at least one incremental configuration to the UE, wherein the at least one incremental configuration specifies one or more changes to the current configuration of the UE.

In another aspect, a method for performing an inter-eNB handover in a wireless communication system is disclosed. The method includes receiving a request for a handover, wherein the request includes information about a current configuration associated with a UE requesting the handover. The method also facilitates determining a delta configuration specifying one or more changes to the current configuration and transmitting the delta configuration in a transparent container, wherein the current configuration is required to facilitate the handover.

In another aspect, an apparatus for facilitating handover within a communication system is disclosed. The apparatus includes a receiver for receiving information related to a current configuration of a UE requesting a handover. The apparatus also includes a processor configured to determine at least one incremental configuration for the UE, wherein the at least one incremental configuration indicates one or more changes to the current UE configuration required to facilitate the handover. A transmitter receives the incremental configuration and transmits the incremental configuration in a transparent container.

Another aspect relates to a computer program product comprising a computer-readable medium, the computer-readable medium comprising: code for causing at least one computer to receive a request for handover, wherein the request includes information about a current configuration associated with a UE requesting handover; code for causing the at least one computer to determine an incremental configuration specifying one or more changes to the current configuration, wherein the one or more changes to the current configuration are required to facilitate handover; and code for causing the at least one computer to send the incremental configuration in a transparent container.

In another aspect, a method for performing a handover within a wireless communication system is disclosed. The method includes the steps of sending a measurement report including a current configuration of a UE, receiving an incremental configuration including one or more changes to the current configuration, and performing the incremental configuration to facilitate the handover. If the handover is an inter-eNB handover from a source eNB (eNodeB) to a preferred target eNB, the preferred target eNB is indicated to the source eNB in the measurement report in addition to information regarding radio conditions associated with the UE. In response, the incremental configuration is received at the UE from the source eNB in a transparent container. The method further includes the step of receiving one or more of critical information or non-critical information from the source eNB based at least on the radio conditions sent in the measurement report. The method further facilitates sending a message to the target eNB upon completion of the handover, the message including information regarding the information received from the source eNB.

According to another aspect, an apparatus for facilitating handover in a wireless communication system is disclosed. The apparatus includes a processor that generates at least one measurement report, the measurement report including information about a current configuration and radio conditions associated with a UE. The apparatus also includes a transmitter for transmitting the measurement report. The apparatus also includes a receiver that receives a message including an incremental configuration, wherein the incremental configuration details changes to the current configuration necessary to facilitate the handover.

In another aspect, the present invention relates to a computer program product comprising a computer-readable medium comprising: code for causing at least one computer to send a measurement report comprising a current configuration of a UE; code for causing at least one computer to receive an incremental configuration comprising one or more changes made to the current configuration; and code for causing at least one computer to implement the incremental configuration to facilitate handover.

According to this aspect, a system for facilitating handover is disclosed. The system includes means for generating a measurement report including a current configuration and radio conditions associated with a UE. Also included within the system is means for transmitting the measurement report. The system also includes means for receiving a handover message including an incremental configuration, wherein the incremental configuration details one or more changes to the current configuration required to facilitate the handover.

The following description and accompanying drawings set forth in detail certain exemplary aspects of the claimed subject matter. However, these aspects are merely indicative of some of the various ways in which the principles of the claimed subject matter may be employed, and the claimed subject matter is intended to include all such aspects and their equivalents. Other advantages and distinguishing features of the claimed subject matter will become apparent from the following detailed description of the claimed subject matter when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 illustrates a multiple access wireless communication system according to one embodiment.

2 is a block diagram of an embodiment of an eNB and an access terminal (or UE) in a MIMO system.

3 is an illustration of a wireless multiple-access communication system in accordance with various aspects described herein.

FIG4 illustrates a handover process performed according to one aspect.

FIG5 illustrates a more detailed operation of a system for performing an inter-eNB handover procedure.

FIG6 illustrates an embodiment of an RRC message in accordance with various aspects described herein.

FIG7 relates to a method for performing an inter-eNB handover according to one aspect.

8A relates to a method for transmitting critical information and/or non-critical information from a target eNB to a UE in an inter-eNB handover according to one aspect.

FIG8B relates to another aspect of sending critical/non-critical information by the source eNB to the UE during an inter-eNB handover.

9 is a flow chart of a method of performing handover according to one aspect.

10 is a flow chart of a method for receiving information according to one aspect.

11 illustrates a high-level system diagram of various components of a device in accordance with various aspects.

12 is another high-level system diagram illustrating various components of a device according to various aspects described herein.

FIG. 13 illustrates a block diagram of an example system for implementing handover according to aspects disclosed herein.

14 illustrates a block diagram of an example system that implements inter-eNodeB handover according to aspects described herein.

DETAILED DESCRIPTION

The claimed subject matter will now be described with reference to the accompanying drawings, wherein like reference numerals are used throughout to indicate like elements. In the following description, for purposes of explanation, numerous specific details are provided to provide a comprehensive understanding of the claimed subject matter. However, it will be apparent that the claimed subject matter may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form to facilitate description of the claimed subject matter.

Various embodiments will now be described with reference to the accompanying drawings, wherein like reference numerals are used throughout to refer to like elements. In the following description, for purposes of explanation, numerous specific details are provided to provide a thorough understanding of one or more aspects. However, it will be apparent that the embodiment(s) may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form to facilitate the description of one or more embodiments. As used in this application, the terms "component," "module," "system," and the like are intended to refer to computer-related entities, including hardware, firmware, a combination of hardware and software, software, or executed software. For example, a component may be, but is not limited to, a process running on a processor, a processor, an integrated circuit, an object, an executable, an executing thread, a program, and/or a computer. By way of example, both an application running on a computing device and the computing device may be a component. One or more components may reside within a process and/or an execution thread, and components may be located on a single computer and/or distributed across two or more computers. Furthermore, these components may be executed from various computer-readable media having various data structures stored thereon. Components may communicate using local and/or remote processes, for example, based on signals having one or more data packets (e.g., data from a component interacting with a local system, another component in a distributed system, and/or with other systems over a network such as the Internet using signals).

Various embodiments are presented with respect to systems including multiple devices, components, modules, etc. It should be understood and appreciated that various systems may include additional devices, components, modules, etc. and/or may not include all of the devices, components, modules, etc. discussed in conjunction with the figures. Combinations of these approaches may also be used.

The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or designs. The word "listen" is used herein to indicate that a receiving device (eNB or UE) is receiving and processing data received on a given channel.

Various aspects may include inference schemes and/or techniques in conjunction with transforming communication resources. As used herein, the term "inference" generally refers to the process of reasoning or inferring the state of a system, environment, and/or user based on a set of observations obtained via events and/or data. For example, inference may be employed to identify a specific context or action, or a probability distribution of states may be generated. In view of the uncertainty in user goals and intentions, inference may be probabilistic, i.e., a probability distribution of the relevant state is calculated based on considerations of data and events, or inference may be a theoretical decision based on probabilistic inferences and taking into account the displayed action with the highest expected utility. Inference may also refer to the techniques employed to construct higher-level events based on a set of events and/or data. Such inference constructs new events or actions based on a set of observed events and/or stored event data, regardless of whether these events are closely related in time and regardless of whether these events and data come from one or more event and data sources.

Furthermore, various aspects are described herein with respect to a subscriber station. A subscriber station is also referred to as a system, subscriber unit, mobile station, mobile station, remote station, access point, eNB, remote terminal, access terminal, user terminal, user agent, user equipment, mobile device, portable communication device, or user device. A subscriber station can be a cellular phone, a cordless phone, a Session Initiation Protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a handheld device with wireless connectivity, or other processing device connected to a wireless modem.

Furthermore, various aspects or features described herein may be implemented as methods, apparatus, or articles of manufacture using standard programming and/or engineering techniques. As used herein, the term "article of manufacture" is intended to encompass a computer program accessible from any computer-readable device, carrier, or medium. For example, computer-readable media include, but are not limited to, magnetic storage devices (e.g., hard disks, floppy disks, magnetic strips, etc.), optical disks (e.g., compact disks (CDs), digital versatile disks (DVDs), etc.), smart cards, and flash memory devices (e.g., cards, sticks, key drives, etc.). Furthermore, the various storage media described herein can represent one or more devices and/or other machine-readable media for storing information. The term "machine-readable medium" includes, but is not limited to, wireless channels and various other media that can store, contain, and/or carry instructions and/or data.

The techniques described herein can be used in various wireless communication networks, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), and single-carrier FDMA (SC-FDMA). The terms "network" and "system" are often used interchangeably. A CDMA network may implement radio technologies such as Universal Terrestrial Radio Access (UTRA) and cdma2000. UTRA includes Wideband CDMA (W-CDMA) and Low Chip Rate (LCR). cdma2000 covers the IS-2000, IS-95, and IS-856 standards. TDMA networks implement radio technologies such as Global System for Mobile Communications (GSM). OFDMA networks implement radio technologies such as Evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, and others. UTRA, E-UTRA, and GSM are part of the Universal Mobile Telecommunications System (UMTS). Long Term Evolution (LTE) is an upcoming release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS, and LTE are described in documents from an organization named the 3rd Generation Partnership Project (3GPP). cdma2000 is described in documents from an organization named the 3rd Generation Partnership Project 2 (3GPP2). These various radio technologies and standards are well known in the art. For simplicity, certain aspects of these technologies are described below for LTE, and LTE terminology is used in much of the following description.

Single-carrier frequency division multiple access (SC-FDMA) is a technique that uses single-carrier modulation and frequency-domain equalization. SC-FDMA offers similar performance to OFDMA and essentially the same global complexity. SC-FDMA signals have a lower peak-to-average power ratio (PAPR) due to their inherent single-carrier structure. SC-FDMA has attracted significant attention, particularly in uplink communications, where lower PAPR significantly benefits mobile terminals in terms of transmit power efficiency. The current working hypothesis is the uplink multiple access scheme in 3GPP Long Term Evolution (LTE), or Evolved UTRA.

Referring to FIG. 1 , a multiple-access wireless communication system according to one embodiment is shown. An eNB 100 includes multiple antenna groups, wherein a first group includes antennas 104 and 106, another group includes antennas 108 and 110, and another group includes antennas 112 and 114. FIG. 1 shows two antennas for each antenna group; however, more or fewer antennas may be used for each antenna group. A user equipment (UE) or access terminal (AT) 116 communicates with antennas 112 and 114, where antennas 112 and 114 transmit information to UE 116 via a forward link 120 and receive information from UE 116 via a reverse link 118. A user equipment (UE) 122 communicates with antennas 106 and 108, where antennas 106 and 108 transmit information to UE 122 via a forward link 126 and receive information from UE 122 via a reverse link 124. In an FDD system, communication links 118, 120, 124, and 126 utilize different frequencies for communication. For example, the frequency used by forward link 120 is different from the frequency used by reverse link 118. Each set of antennas and/or the area in which they are designed to communicate is often referred to as a sector of an access point and/or eNB. In this embodiment, each antenna group is designed to communicate with UEs in a sector within the area covered by eNB 100.

In communications over forward links 120 and 126, the transmit antennas of eNB 100 employ beamforming to improve the signal-to-noise ratio of the forward links for the different UEs 116 and 124. Furthermore, the eNB uses beamforming to transmit to UEs randomly dispersed throughout its coverage area, thereby introducing less interference to UEs in adjacent sectors, compared to the eNB transmitting to all of its UEs via a single antenna.

An eNB may be a fixed station for communicating with terminals and may also be referred to as an access point, Node B, enhanced Node B (eNB), or some other terminology. An access terminal (AT) may also be referred to as user equipment (UE), a wireless communication device, terminal, or some other terminology.

2 is a block diagram of an embodiment of an eNB 210 and an access terminal (AT) or user equipment (UE) 250 in a MIMO system 200. At the eNB 210, traffic data for a number of data streams is provided from a data source 212 to a transmit (TX) data processor 214.

In one embodiment, each data stream is transmitted through a corresponding transmit antenna. TX data processor 214 formats, codes, and interleaves the traffic data for that data stream based on a particular coding scheme selected for that data stream to provide coded data.

The coded data for each data stream can be multiplexed with pilot data using OFDM techniques. The pilot data is typically a known data scheme processed in a known manner and can be used at the receiving system to estimate the channel response. The multiplexed pilot and coded data for each data stream is then modulated according to a particular modulation scheme selected for that data stream (e.g., BPSK, QSPK, M-PSK, or M-QAM) to provide modulation symbols. Instructions executed by processor 230 determine the data rate, coding, and modulation for each data stream.

The modulation symbols for all data streams are then provided to a TX MIMO processor 220, which may further process the modulation symbols (e.g., for OFDM). The TX MIMO processor 220 then provides NT modulation symbol streams to NT transceivers (TMTR) 222a through 222t. In a particular embodiment, the TX MIMO processor 220 applies beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted.

Each transceiver 222 receives and processes a corresponding symbol stream to provide one or more analog signals and further conditions (e.g., amplifies, filters, and upconverts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. NT modulated signals from transceivers 222a through 222t are then transmitted from NT antennas 224a through 224t, respectively.

At UE 250, the transmitted modulated signals are received by NR antennas 252a through 252r and the received signal from each antenna 252 is provided to a respective transceiver (RCVR) 254a through 254r. Each transceiver 254 conditions (e.g., filters, amplifies, and downconverts) a respective received signal, digitizes the conditioned signal to provide samples, and further processes the samples to provide a corresponding "received" symbol stream.

An RX data processor 260 then receives and processes the NR received symbol streams from NR transceivers 254 based on a particular transceiver processing technique to provide NT "detected" symbol streams. The received symbols or other information may be stored in an associated memory 272. The RX data processor 260 then demodulates, deinterleaves, and decodes each detected symbol stream to recover the traffic data for the data stream. The processing by the RX data processor 260 is complementary to that performed by the TX MIMO processor 220 and the TX data processor 214 at the eNB 210.

Processor 270 periodically determines which precoding matrix to use (discussed below). Processor 270 formulates a reverse link message comprising a matrix index portion and a rank value portion.

Reverse link messages include various types of information about the communication link and/or the received data stream. For example, reverse link communications include periodic measurement reports from the UE 250 to the serving eNB 210. According to various aspects detailed below, these measurement reports include one or more radio conditions associated with the UE, or if a handover is desired, the measurement reports include information about the preferred target eNB; alternatively, reverse link communications can be used to inform the UE whether it has received one or more of critical information or non-critical information. The information received on the reverse link can be stored in the associated memory 232. The reverse link message is then processed by the TX data processor 238, modulated by the modulator 280, conditioned by the transceivers 254a-254r, and sent back to the transmit system 210, where the TX data processor 238 also receives traffic data for multiple data streams from the data source 236.

At eNB 210, the modulated signal from receive system 250 is received by antenna 224, conditioned by transceiver 222, demodulated by demodulator 240, and processed by RX data processor 242 to extract the reverse link message sent by transceiver system 250. Processor 230 then determines which precoding matrix to use to determine the beamforming weights and then processes the extracted message.

In one aspect, logical channels are categorized into control channels and traffic channels. Logical control channels include the Broadcast Control Channel (BCCH), a DL channel used to broadcast system control information; the Paging Control Channel (PCCH), a DL channel used to transmit paging information; and the Multicast Control Channel (MCCH), a Point-to-multipoint DL channel used to transmit Multimedia Broadcast and Multicast Service (MBMS) scheduling and control information for one or more Multicast Traffic Channels (MTCHs). Typically, after an RRC connection is established, this channel is used only by UEs receiving MBMS. The Dedicated Control Channel (DCCH) is a Point-to-point bi-directional channel used to transmit dedicated control information and is used by UEs with an RRC connection. In one aspect, logical traffic channels include the Dedicated Traffic Channel (DTCH), a Point-to-point bi-directional channel dedicated to a single UE for transmitting user information; and the Multicast Traffic Channel (MTCH), a Point-to-multipoint DL channel used to transmit traffic data.

In one aspect, transport channels are categorized into DL and UL transport channels. DL transport channels include the broadcast channel (BCH), the downlink shared channel (DL-SCH), and the paging channel (PCH). The PCH is used to support UE power saving (the DRX cycle is indicated to the UE by the network), is broadcast throughout the cell, and is mapped to physical layer (PHY) resources that can be used for other control/traffic channels. The DL transport channel associated with MBMS is the multicast channel (MCH). UL transport channels include the random access channel (RACH), the uplink shared data channel (UL-SDCH), and multiple physical layer (PHY) channels. PHY channels comprise a set of DL and UL channels.

DL PHY channels and signals include:

Reference Signal (RS)

Primary synchronization signal and secondary synchronization signal (PSS/SSS)

Physical Downlink Shared Channel (PDSCH)

Physical Downlink Control Channel (PDCCH)

Physical Multicast Channel (PMCH)

Physical HARQ Indicator Channel (PHICH)

Physical Control Formatting Indicator Channel (PCFICH)

UL PHY channels include:

Physical Random Access Channel (PRACH)

Physical Uplink Control Channel (PUCCH)

Channel Quality Indicator (CQI)

Precoding Matrix Indicator (PMI)

Rank Indicator (RI)

Scheduling Request (SR)

Uplink ACK/NAK

Physical Uplink Shared Channel (PUSCH)

Sounding Reference Signal (SRS)

In one aspect, a channel structure is provided that maintains the low PAR (at any given time, the channels are continuous or evenly spaced in frequency) property of a single carrier waveform.

For the purposes of this article, the following abbreviations apply:

AM Confirmation Mode

AMD Deterministic Mode Data

ARQ Automatic Repeat Request

BCCH Broadcast Control Channel

BCH Broadcast Channel

C- Control-

CCCH Common Control Channel

CCH Control Channel

CCTrCH Coded Composite Transport Channel

CP Cyclic Prefix

CRC Cyclic Redundancy Check

CTCH Common Traffic Channel

DCCH Dedicated Control Channel

DCH Dedicated Channel

DL Downlink

DSCH Downlink Shared Channel

DTCH Dedicated Traffic Channel

FACH Forward Link Access Channel

FDD Frequency Division Duplex

L1 Layer 1 (physical layer)

L2 Layer 2 (Data Link Layer)

L3 Layer 3 (Network Layer)

LI length indicator

LSB Least Significant Bit

MAC Media Access Control

MBMS Multimedia Broadcast Multicast Service

MCCH MBMS point-to-multipoint control channel

MRW Mobile Receive Window

MSB Most Significant Bit

MSCH MBMS point-to-multipoint scheduling channel

MTCH MBMS point-to-multipoint service channel

PCCH Paging Control Channel

PCH Paging Channel

PDU Protocol Data Unit

PHY Physical Layer

PhyCH Physical Channel

RACH Random Access Channel

RLC Radio Link Control

RRC Radio Resource Control

SAP Service Access Point

SDU Service Data Unit

SHCCH Shared Channel Control Channel

SN Serial Number

SUFI Super Field

TCH Traffic Channel

TDD Time Division Duplex

TFI Transmission Format Indicator

TM Transparent Mode

TMD Transparent Mode Data

TTI Transmission Time Interval

U- User-

UE User Equipment

UL Uplink

UM Unconfirmed Mode

UMD Unconfirmed Mode Data

UMTS Universal Mobile Telecommunications System

UTRA UMTS Terrestrial Radio Access

UTRAN UMTS Terrestrial Radio Access Network

MBSFN Multicast Broadcast Single Frequency Network

MCE MBMS Coordination Entity

MCH Multicast Channel

DL-SCH Downlink Shared Channel

MSCH MBMS control channel

PDCCH Physical Downlink Control Channel

PDSCH Physical Downlink Shared Channel

MBSFN Multicast Broadcast Single Frequency Network

MCE MBMS Coordination Entity

MCH Multicast Channel

DL-SCH Downlink Shared Channel

MSCH MBMS control channel

PDCCH Physical Downlink Control Channel

PDSCH Physical Downlink Shared Channel

PUCCH Physical Uplink Control Channel

PUSCH Physical Uplink Shared Channel

FIG3 is a diagram of a wireless multiple-access communication system 300 according to various aspects. In one example, the wireless multiple-access communication system 300 includes multiple eNBs 310 and multiple UEs 320. Each eNB 310 provides communication coverage for a specific geographic area 302 (e.g., 302a, 302b, 302c). The term "cell" can refer to an eNB and/or its coverage area, depending on the context in which the term is used. To improve system capacity, the access terminal coverage area can be divided into multiple smaller areas, such as three smaller areas 304a, 304b, and 304c. Each smaller area is served by a corresponding eNB. The term "sector" can refer to an eNB and/or its coverage area, depending on the context in which the term is used. For a sectorized cell, the eNBs for all sectors of the cell are typically co-located within the cell's base station. The signaling techniques described herein can be used in systems with sectorized cells as well as systems with non-sectorized cells. For simplicity, in the following description, the term "base station" or "eNB" is used generically to refer to a station serving a sector as well as a station serving a cell.

Terminals or UEs 320 are typically dispersed throughout the system, and each UE can be fixed or mobile. A terminal may also be referred to as, and include some or all of the functions of, a mobile station, a user equipment, and/or some other device. A terminal may be a wireless device, a cellular phone, a personal digital assistant (PDA), a wireless modem card, etc. A terminal may not be communicating with a base station, or may be communicating with one or more base stations on the forward and reverse links at any given moment.

For a centralized architecture, a system controller 330 is coupled to the APs 310 and provides coordination and control for these base stations. The system controller 330 can be a single network entity or a collection of network entities. For a distributed architecture, the eNBs 310 can communicate with each other as needed.

This document describes one or more aspects of wireless communication system design to support full-duplex FDD (frequency division duplex) and TDD (time division duplex) or half-duplex FDD (frequency division duplex) and TDD (time division duplex) modes of operation while supporting scalable bandwidth. However, this is not necessarily the case with the previous modes, and other modes may also be supported in addition or as an alternative. Furthermore, it should be noted that the concepts and approaches herein do not necessarily need to be used in conjunction with any other concepts or approaches described herein.

A handover occurs when a UE moves from one cell to another served by a different eNB. The UE moves from the source eNB currently serving the UE to a target eNB that can better serve the UE due to changing radio conditions. This determination is based on measurement reports received from the UE, which include measurements of neighboring cells sent by the UE. The source eNB controls other aspects of the handover process, such as UE measurement reporting (e.g., the periodicity of Channel Quality Information (CQI) reporting), the transfer of the UE context from the source eNB to the target eNB, and so on. For example, the physical layer at the source eNB processes the measurement reports from the UE and sends appropriate instructions to higher layers.

Figure 4 illustrates a handover procedure performed according to one aspect. In the figure, 402 is a source or serving eNB that maintains the coupling between the mobility tunnel and radio bearers and also maintains the UE context associated with UE 404. When UE 404 moves from one cell to another, source eNB 402 begins preparing for the handover by sending coupling information and the UE context to a selected target eNB 406. This can be triggered by a measurement report from UE 404 informing of its current radio conditions, based on which the target eNB 406 is selected. Once the target eNB 406 announces its readiness to take over UE 404, source eNB 402 can instruct UE 404 to transition its radio bearers to the target eNB 406. For the handover to complete, the serving gateway (S-GW) must update its log with the new target eNB 406 currently serving UE 404. Accordingly, the MME (Mobility Management Entity) coordinates the handover of the mobility tunnel from source eNB 402 to target eNB 406. The MME may be a signaling only entity that does not receive user IP packets but facilitates UE mobility. It triggers an update at the S-GW based on signaling received from the target eNB 406 indicating that the radio bearer has been successfully transferred.

According to the above process, when UE 404 needs to change its serving eNB, it sends a measurement report to source eNB 402, including a preferred target eNB 406. This is indicated in the figure as uplink communication from the UE to the source eNB (a). Consequently, the source eNB transfers the UE context to the target eNB in a HO (Handover) Request (b). The target eNB announces its acceptance of the HO Request in a HO Accept message (c). Upon receiving the HO Accept message from the target eNB, the source eNB announces a HO Command to the UE (d). In various aspects further detailed below, the target eNB may send a HO Command to the source eNB, which forwards the HO Command to the UE. The HO Complete message sent from the UE to the target eNB may be used by the target eNB to trigger the MME, as shown at (e), to perform a user plane update at the S-GW (f). Consequently, as shown at (g), the mobility tunnel is switched from source eNB 402 to target eNB 406.

Figure 5 illustrates the operation of the aforementioned system in more detail. As described above, upon receiving signaling from the UE regarding the preferred target eNB, as indicated in a measurement report, a handover ("inter-eNB handover") occurs from the source eNB currently serving the UE to the target eNB. According to another aspect, the source eNB informs the target eNB of the requesting UE's current configuration in a HO Request message. This information can be used by the target eNB to generate a response containing the UE's full or incremental configuration in a transparent container. The target eNB then compares the current UE configuration with the target eNB's desired configuration and generates an incremental configuration containing the target eNB's desired changes to the current UE configuration. This incremental configuration can be sent from the target eNB to the source eNB in a transparent container via a HO Request Confirmation message. The transparent container facilitates the source eNB forwarding the incremental configuration to the UE without having to know the detailed contents of the container. This mechanism allows for combinations of source and target eNBs that may support different protocol versions or have different policies for radio configuration (e.g., due to being from different vendors). The UE can receive the transparent container forwarded by the source eNB in a HO Command message. Therefore, while it is beneficial to include in the handover message the measurement configuration that the UE needs to use in the target eNB, it is also important to reduce the actual size of the handover message for reliable delivery.

Therefore, another aspect relates to a transmission scheme that enables the source eNB to select the information transmitted in the handover message, thereby reducing the information included in the message sent to the UE. For example, the target eNB does not know whether conditions at the source eNB (eNB) allow non-critical information to be transmitted along with critical information. Therefore, the source eNB indicates in the HO REQUEST message whether non-critical configurations can be sent. Only if permitted does the target eNB forward the non-critical configurations to the source eNB in the HO REQUEST ACKNOWLEDGE message. According to this aspect, no additional messages other than the HO REQUEST/HO REQUEST ACKNOWLEDGE messages need to be transmitted over X2. However, this does not address situations where non-critical configurations cannot be reliably delivered to the UE due to sudden changes in radio conditions caused by periodic HO command transmissions. The only option left to the source eNB with this option is to attempt to transmit both critical and non-critical information. While the additional signaling from the source eNB or UE regarding the information transmitted during the handover is contrary to conventional techniques, it enables the UE to perform a reliable handover, thereby improving service.

Therefore, a transmission scheme within a wireless communication system is advantageous in which the source eNB can choose whether to transmit non-critical configurations in a handover message. In this regard, the target eNB can transmit non-critical information to the source eNB regardless of any signaling from the source eNB regarding the non-critical information. If the non-critical information is not transmitted to the UE, the source eNB can notify the target eNB that no transmission was performed. Alternatively, the UE can notify the target eNB of the information received from the source eNB via a HO COMPLETE message.

Figure 6 relates to aspects of inter-eNB handover, in which the radio configuration used in the target eNB is announced from the target eNB to the source eNB in a transparent container. Furthermore, the HO command message from the source eNB includes the transparent container. This indicates that the source eNB does not need to understand the detailed contents of the container. As described above, this mechanism allows for combinations of source and target eNBs that may support different protocol versions or have different policies regarding radio configuration. In the figure, 602 is equivalent to an RRC message in a WCDMA system with multiple instances of the top-level IE (Information Element), for which the basic procedure is specified. This works in conjunction with the inter-eNB handover mechanism, in which the relevant IE is provided to the source eNB by the target eNB. In the case of an inter-eNB handover, the source eNB includes the transparent container received from the target eNB in the RRC CONNECTION CHANGE COMMAND message. This is achieved by the target eNB including the top-level IE in the transparent container. Therefore, for top-level IEs using transparent containers, a choice between the source eNB's local configuration and the transparent container can be shown in RRCCONNECTIONCHHANGECOMAND message 604. Message 604 thus facilitates both inter-eNB handovers using transparent containers and intra-eNB handovers using local configuration. In the latter case, the UE can move from one cell to another associated with the same eNB, thus eliminating the need for a transparent container. In the former case, the UE can decode the transparent container to identify the protocol version included within it. This facilitates transmitting only the top-level IE (but not the entire message) over the X2 interface (an additional interface between eNBs defined under LTE to facilitate inter-eNB handover). Thus, as can be seen from message 604, the choice option separates the top-level IE between the local configuration (where the UE remains within the same eNB) and the transparent container (where the UE moves from one eNB to a different one).

However, to simplify explanation, one or more methods herein, for example, as shown in a flow chart, are shown and described as a series of actions, but it should be understood and appreciated that the present invention is not limited to the order of the actions, because according to the present invention, some actions may occur in different orders and/or simultaneously with other actions shown and described herein. For example, one skilled in the art will understand and appreciate that a method may alternatively be represented as a series of related states or events, for example, in a state diagram. Furthermore, not all of the actions shown are required to perform a method according to the present invention.

FIG7 relates to a method 700 for performing an inter-eNB handover according to one aspect. The method begins at 702, where a source eNB receives a measurement report from a UE that includes information about a preferred target eNB. At 704, the source eNB forwards a HO REQUEST message including information about the UE's current configuration to the preferred target eNB. At 706, the source eNB receives a HOREQUESTACK message (Handover Request Acknowledgement) from the target eNB. In a more detailed aspect, the acknowledgment message may include an incremental configuration, wherein the target eNB compares the current UE configuration received in the HO REQUEST message and specifies the desired changes to the current UE configuration as the incremental configuration in the acknowledgment message. In another aspect, the incremental configuration may be specified in a transparent container. At 708, the source eNB forwards the transparent container specifying the incremental configuration to the UE via a HO COMMAND message. This message facilitates the transfer of the UE from the source eNB to the target eNB. The transparent container alleviates the need for the source eNB to examine the details of the incremental configuration to generate the HO COMMAND message; the source eNB simply forwards the transparent container to the UE in the HO COMMAND message. The process then reaches an end block.

FIG8A relates to a method 800 for transmitting critical and/or non-critical information from a target eNB to a UE during an inter-eNB handover, according to one aspect. The process begins at 802, where a source eNB receives a message including a measurement report from a UE it serves. The measurement message indicates not only the current radio conditions associated with the UE but also the UE's preferred target eNB. Based at least on the radio conditions associated with the UE, the source eNB determines information that can be transmitted to the UE. Specifically, as shown in 804, the source eNB determines whether any non-critical information received from the target eNB regarding the handover can be transmitted to the UE. For example, if the UE has good signal-to-noise ratio (SNR) characteristics or favorable service options, the source eNB may determine that all information, including both critical and non-critical information, can be transmitted to the UE. Conversely, if the UE faces minimal resources, only information critical for performing the handover can be transmitted to it. If the UE has favorable radio conditions, the source eNB notifies the target eNB to transmit critical and non-critical information to the UE, as shown in 808. Otherwise, only critical information is requested from the target eNB, as shown in 806. According to one aspect, this can be announced by the source eNB in a HO REQUEST message. Once the appropriate HO REQUEST message is sent, the source eNB receives a HO REQUEST ACK message including the information requested at 810. This information is forwarded to the UE in a HO COMMAND message, as indicated at 812. According to another aspect, the target eNB sends the information to the source eNB in a transparent container, wherein the contents of the transparent container are not inspected by the source eNB, and the source eNB simply forwards the transparent container to the UE in a HO COMMAND message.

FIG8B depicts a flowchart 820 illustrating another aspect of transmitting critical/non-critical information by a source eNB to a UE during an inter-eNB handover. The process begins at 822, where the source eNB receives a measurement message from the UE indicating favorable radio conditions. Then, at 824, the source eNB requests critical and non-critical information from a preferred target eNB. At 826, a determination is made as to whether radio conditions associated with one or more of the source eNB or the UE have changed. If the radio conditions have not changed, the source eNB transmits all information received from the target eNB to the UE, as shown at 828. If the radio conditions associated with one or more of the UE or the source eNB have changed, a determination is made as to whether the change is favorable, as shown at 830. If the change is favorable, the process returns to 828, where the source eNB transmits all received information, including critical and non-critical information, to the UE. However, if the change is determined to be unfavorable at 830, the source eNB transmits only the critical information, as shown at 832. The target eNB is informed that no non-critical information was sent, and the process terminates at the stop block, as shown in 834. Alternatively, the process may terminate without notifying the target eNB, with the UE notifying the target eNB of all received information in the HO COMPLETE message it sends.

FIG9 is a flow chart 900 of a method for performing a handover according to one aspect. The method begins at 902, where a UE desiring an inter-eNB handover sends a message including a measurement report to its serving source eNB. The measurement message includes information regarding radio conditions associated with the UE, its current configuration, and a preferred target UE. In response, as shown at 904, a HO COMMAND message is received from the source eNB, where the message includes information regarding an incremental configuration detailing changes to the current UE configuration for transmission to the preferred target eNB. According to a more detailed aspect, the incremental configuration may be transmitted in a transparent container. In another aspect, the UE may maintain its current configuration, where the contents of the transparent container do not cause changes to the current UE configuration. Then, at 906, a determination is made as to whether the UE should change any parameters associated with its current configuration. If so, the changes detailed in the incremental configuration received in the HO COMMAND message are implemented as the current configuration, as shown at 908, and the UE is associated with the preferred target eNB, as shown at 910. If, at 906, it is determined that no changes are necessary to the current UE configuration, the UE maintains its current configuration, as shown at 912. The process moves to 910, where the UE is associated with the preferred target eNB, and the process then terminates at the stop block. Although the methods described herein detail handover of a UE from one eNB to another, it should be understood that it is not necessary for the UE to perform an inter-eNB handover. The same process can be applied for intra-eNB handovers when the UE moves between cells associated with the same eNB.

FIG10 is a flow chart 1000 of a method for receiving information, according to one aspect. The method begins at 1002, where a UE requiring inter-eNB handover sends a measurement report to its source eNB. The measurement report may include information regarding radio conditions associated with the UE and the UE's preferred target eNB. Based on the received measurement report, the source eNB determines whether the UE can receive both critical and non-critical information from the preferred target eNB, or whether only critical information should be forwarded. Then, at 1004, the UE receives a HO COMMAND message, which includes information included by the source eNB based on its understanding of the radio conditions from the measurement report. At 1006, the message received from the source eNB is decoded, and at 1008, the transmitted information is determined. As shown in 1010, the method performs a handover to the preferred target eNB. At 1012, after the handover is complete, the UE transmits the information received from the source eNB to the target eNB in a HO COMPLETE message, thereby notifying the target eNB of the receipt/non-receipt of non-critical information.

FIG11 illustrates a high-level system diagram of various components of a device according to various aspects. It should be appreciated that device 1100 can be an eNodeB, a UE, or a combination thereof. It includes a communication component 1102, which employs hardware, software, and services as described herein to facilitate receiving and sending communications to various entities. While communication component 1102 is depicted as a single entity, it should be appreciated that separate transmitting and receiving components may be employed to send and receive communications. According to one aspect, device 1100 can function as an eNodeB, and communication component 1102 receives transmissions from various UEs regarding one or more resource requests, data transmissions, and the like. Analysis component 1104 analyzes communications received from various UEs to identify any UEs requesting handover. Analysis component 1104 may include a single or multiple processors or multi-core processors, wherein the processors may perform other operations, such as decoding messages received from UEs to determine associated radio conditions or a preferred target eNB for a UE requesting handover, generating messages for requesting handover, or generating information to facilitate handover (e.g., generating a delta configuration for the UE). Furthermore, analysis component 1104 may be implemented as an integrated processing system and/or a distributed processing system. The information collected by the analysis component 1104 can be stored in the memory 1106/data storage 1108 for further processing. The memory 1106 can include random access memory (RAM), read-only memory (ROM), or a combination thereof. The data storage 1108 can be any suitable combination of hardware and/or software that supports mass storage of information, databases, and programs employed in conjunction with the aspects described herein.

12 is another high-level diagram illustrating various components of a device 1200 in accordance with various aspects described herein. The device 1200 may be an eNodeB, a UE, or a combination thereof. The device includes a transmitting component 1202 for transmitting various transmissions. If the device is used as a UE, the transmitting component 1202 may transmit various communications on the uplink to a serving eNodeB/base station. The communications may include resource requests, data transmission on allocated resources, or other control communications (e.g., measurement reports that transmit radio conditions or a preferred target eNB for handover, etc.). The device also includes a receiving component 1204 for receiving communications from various entities including eNodeBs, other UEs, or a combination thereof. According to one aspect, once the measurement report requesting a handover is sent, the device 1200 may receive transmissions of control messages such as HOCOMMAND messages. These messages may be stored in a data store 1206. The data store 1206 may be a data store that supports the communication of information used in conjunction with the aspects described herein. The device 1200 may include any suitable combination of hardware and/or software for mass storage of information, databases, and programs. Device 1200 may optionally include volatile/non-volatile memory 1208, including random access memory (RAM), read-only memory (ROM), or a combination thereof. Received messages are decoded and processed by processing component 1210. According to one aspect, messages related to handovers may include one or more of critical information or non-critical information to facilitate handovers. Information decoded from such control messages may be stored in memory 1208 and/or data storage 1206 and may be used by processing component 1210 to control handovers or other processes.

Next, a system that can implement aspects of the disclosed subject matter is described in conjunction with Figures 13 and 14. Such a system may include functional blocks, which may be functional blocks that represent functions performed by a processor or electronic machine, software, or a combination thereof (eg, firmware).

FIG13 illustrates a block diagram of an exemplary system 1300 for implementing handover according to aspects disclosed herein. For example, system 1300 can reside at least partially within a base station. System 1300 includes a logical grouping 1310 of electrical components that can operate in conjunction. In one aspect of the present disclosure, logical grouping 1310 includes an electrical component 1315 for receiving one or more measurement reports from one or more UEs detailing a current configuration associated with the UEs, an electrical component 1325 for analyzing the measurement reports to determine at least one UE requesting handover, and an electrical component 1335 for sending a message to the UE including at least one incremental configuration specifying one or more changes to the UE's current configuration.

System 1300 also includes a memory 1340 that holds instructions for executing functions associated with electronic components 1315, 1325, and 1335, as well as measurement data or calculation data generated during execution of these functions. Although one or more electronic components 1315, 1325, and 1335 are shown as being external to memory 1340, it should be understood that one or more electronic components 1315, 1325, and 1335 can be located within memory 1340.

FIG14 illustrates a block diagram of an example system 1400 for implementing inter-eNB handover according to aspects of the present specification. For example, system 1300 can reside at least partially within a mobile station. System 1400 includes a logical grouping 1410 of electrical components capable of operating in conjunction. In one aspect of the present disclosure, logical grouping 1410 includes an electrical component 1415 for generating a measurement report including a current configuration and radio conditions associated with a UE, an electrical component 1425 for transmitting the measurement report, and an electrical component 1435 for receiving a handover message, wherein the handover message includes a delta configuration detailing one or more changes to the current configuration required to facilitate the handover.

The system 1400 may also include a memory 1440 that stores instructions for executing functions associated with the electronic components 1415, 1425, and 1435, as well as measurement data or calculation data generated during the execution of these functions. Although one or more of the electronic components 1415, 1425, and 1435 are shown as being external to the memory 1440, it should be understood that one or more of the electronic components 1415, 1425, and 1435 may be located within the memory 1440.

The foregoing includes examples of various embodiments. Of course, for purposes of describing the embodiments, it is not possible to describe all conceivable combinations of components or methods, but those skilled in the art will appreciate that many further combinations and permutations are possible. Therefore, the detailed description is intended to embrace all alternatives, modifications, and variations that fall within the spirit and scope of the appended claims.

Specifically, and with respect to the various functions performed by the aforementioned components, devices, circuits, systems, and the like, the terms used to describe such components (including references to "modules") are intended to correspond (unless otherwise indicated) to any component that performs the designated functions of the component (e.g., a functional equivalent), even if not structurally equivalent to the disclosed structure, which performs the functions in the exemplary aspects of the embodiments shown herein. In this regard, it should also be appreciated that the embodiments include systems and computer-readable media having computer-executable instructions for performing the acts and/or events of the various methods.

Furthermore, while a particular feature may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of other implementations as may be desired and advantageous for any given application or particular applications. Furthermore, to the extent the words "comprising" and "including" and variations thereof are used in the detailed description or claims, these terms are intended to be inclusive in a manner similar to the word "comprising."

Claims (64)

1. A method for performing an enhanced Node B (eNB) handover by a user equipment (UE), comprising: Sending a measurement report to the source eNB, wherein the measurement report includes information about the preferred target eNB; and receiving a handover message from the source eNB in response to the measurement report, the handover message including a configuration required by a target eNB for the UE to perform the handover, wherein the configuration is generated by the target eNB and forwarded from the source eNB to the UE, wherein the source eNB does not have access to the configuration. 2. The method of claim 1 , wherein the configuration comprises an incremental configuration having one or more changes made to a current configuration of the UE as determined by the target eNB. 3. The method of claim 1, wherein the configuration is received from the source eNB in a transparent container. 4. The method according to claim 1, wherein the step of receiving the handover message comprises: The handover message is received in a radio resource control (RRC) message. 5. The method of claim 4, wherein the RRC message includes configuration information to facilitate mobility between the source eNB and the target eNB. The method of claim 5 , wherein the RRC message comprises an RRC connection change command message. 7. The method of claim 6, wherein the configuration required by the target eNB comprises an information element (IE) to facilitate setting the configuration by the source eNB in the RRC connection change command message. 8. The method of claim 1, wherein the measurement report includes information indicating that the target eNB is a preferred target eNB. 9. The method of claim 1, wherein the measurement report includes information about current radio conditions at the UE. 10. The method of claim 2, wherein the incremental configuration is generated based on a comparison, performed at the target eNB, between the current configuration and a new configuration of the UE associated with the target eNB. 11. The method of claim 1 , wherein the handover message includes configuration parameters specified by the target eNB. 12 . The method of claim 1 , wherein the source eNB and the target eNB support different protocol versions or have different policies for radio configuration. 13. The method of claim 1, wherein: The handover message includes an RRC connection change message, wherein the RRC connection change message includes a transparent container having a radio configuration for the UE at the target eNB, and wherein the radio configuration includes at least one of a radio resource configuration, a security configuration, or a measurement configuration; and The method further comprises: decoding the transparent container to obtain the radio configuration; implementing the radio configuration at the UE; and A handover complete message is sent from the UE to the target eNB. 14. The method of claim 13, further comprising: Based on the radio configuration, a protocol version of the target eNB is determined. 15. The method of claim 13, wherein the radio configuration comprises a complete configuration for the UE at the target eNB. 16. The method of claim 13, wherein the radio configuration comprises a delta configuration relative to a current UE configuration. 17. The method of claim 13, wherein the measurement report includes information about current radio conditions at the UE. 18. A user equipment (UE) apparatus for performing enhanced inter-Node B (eNB) handover in a wireless communication system, comprising: means for sending a measurement report to a source eNB, wherein the measurement report includes information about a preferred target eNB; and means for receiving a handover message from the source eNB in response to the measurement report, the handover message including a configuration required by a target eNB for the UE to perform the handover, wherein the configuration is generated by the target eNB and forwarded from the source eNB to the UE, wherein the source eNB does not have access to the configuration. 19. The user equipment apparatus of claim 18, wherein the configuration comprises an incremental configuration having one or more changes made to a current configuration of the UE determined by the target eNB. 20. The user equipment apparatus of claim 18, wherein the configuration is received from the source eNB in a transparent container. 21. The user equipment apparatus of claim 18, wherein the measurement report includes information about a preferred target eNB or current radio conditions at the UE. 22. The user equipment apparatus of claim 19, wherein the incremental configuration comprises one or more changes specified by the target eNB, one or more changes made to a current configuration of the UE to facilitate an inter-eNB handover, or configuration parameters specified by the target eNB. 23. The user equipment apparatus of claim 19, wherein the incremental configuration is generated based on a comparison performed at the target eNB between a current configuration of the UE and a new configuration for the UE at the target eNB. 24. The user equipment device of claim 18, wherein: The handover message includes an RRC connection change message, wherein the RRC connection change message includes a transparent container having a radio configuration for the UE at the target eNB, and wherein the radio configuration includes at least one of a radio resource configuration, a security configuration, or a measurement configuration; and The user equipment device further includes: means for decoding the transparent container to obtain the radio configuration; means for implementing the radio configuration at the UE; and Means for sending a handover complete message from the UE to the target eNB. 25. A method for inter-enhanced Node B (eNB) handover in a wireless communication system, comprising: receiving, at a target eNB, a handover request message for a user equipment (UE) to be handed over from a source eNB to the target eNB; determining a configuration required by the target eNB related to the handover, wherein the configuration is specified by the target eNB for the UE; A handover request confirm message including the configuration is sent from the target eNB to the source eNB, the handover request confirm message being designed to enable the source eNB to forward the configuration to the UE, wherein the source eNB does not have access to the configuration. 26. The method of claim 25, wherein the configuration comprises an incremental configuration with one or more changes specified by the target eNB. 27. The method of claim 26, wherein the incremental configuration is generated based on a comparison, performed at the target eNB, between a current configuration of the UE and a new configuration for the UE required at the target eNB in relation to the handover. 28. The method of claim 25, further comprising: A transparent container is generated at the target eNB, where the transparent container includes the configuration specified by the target eNB. 29. The method of claim 28, wherein the transparent container includes configuration parameters specified by the target eNB for changing a current configuration of the UE to facilitate the handover to the target eNB. 30. The method of claim 25, wherein: The handover request message includes UE context information; The configuration includes a radio configuration, the radio configuration including at least one of a security configuration, a measurement configuration, or a radio resource configuration for the UE at the target eNB; and The handover request confirmation message is sent in a transparent container. 31. The method of claim 30, wherein the radio configuration comprises a full configuration for the UE at the target eNB. 32. The method of claim 30, wherein the radio configuration comprises incremental configuration related to the UE context information. 33. The method of claim 30, wherein the target eNB communicates according to a first protocol version or a first radio configuration, and the source eNB communicates according to a second protocol version or a second radio configuration different from the target eNB. 34. An apparatus for inter-enhanced Node B (eNB) handover, comprising: means for receiving, at a target eNB, a handover request message for a user equipment (UE) to be handed over from a source eNB to the target eNB; means for determining a configuration required by the target eNB related to the handover, wherein the configuration is specified by the target eNB for the UE; Means for sending a handover request confirm message including the configuration from the target eNB to the source eNB, the handover request confirm message being designed to enable the source eNB to forward the configuration to the UE, wherein the source eNB does not have access to the configuration. 35. The apparatus of claim 34, wherein the configuration comprises an incremental configuration with one or more changes specified by the target eNB. 36. The apparatus of claim 35, wherein the incremental configuration is generated based on a comparison, performed at the target eNB, between a current configuration of the UE and a new configuration for the UE required at the target eNB in connection with the handover. 37. The apparatus of claim 34, further comprising: Means for generating, at the target eNB, a transparent container comprising the configuration specified by the target eNB. 38. The apparatus of claim 37, wherein the transparent container includes configuration parameters specified by the target eNB for changing a current configuration of a UE to facilitate the handover to the target eNB. 39. The apparatus of claim 34, wherein: The handover request message includes UE context information; The configuration includes a radio configuration, the radio configuration including at least one of a security configuration, a measurement configuration, or a radio resource configuration for the UE at the target eNB; and The handover request confirmation message is sent in a transparent container. 40. A method for inter-enhanced Node B (eNB) handover, comprising: receiving, at a source eNB, a measurement report from a user equipment (UE), wherein the measurement report includes information about a preferred target eNB; Sending a handover request message from the source eNB to the target eNB; receiving, at the source eNB, a handover request confirm message from the target eNB, the handover request confirm message including a configuration required by the target eNB for the UE related to the handover, the handover request confirm message being designed to enable the source eNB to forward the configuration to the UE, wherein the source eNB does not have access to the configuration; and The configuration is forwarded from the source eNB to the UE. 41. The method of claim 40, wherein the configuration comprises an incremental configuration with one or more changes specified by the target eNB. 42. The method of claim 41, wherein the incremental configuration is generated based on a comparison, performed at the target eNB, between a current configuration and a new configuration of the UE associated with the target eNB. 43. The method of claim 40, further comprising: A transparent container is received as part of the handover request acknowledgement, the transparent container including the configuration determined by the target eNB. 44. The method of claim 43, wherein the transparent container includes configuration parameters specified by the target eNB for changing a current configuration of a UE to facilitate the handover to the target eNB. 45. The method of claim 40, wherein the step of forwarding the configuration comprises: Setting the configuration in a Radio Resource Control (RRC) message; and Sending the RRC message to the UE. 46. The method of claim 45, wherein the RRC message includes reconfiguration information to facilitate mobility between the source eNB and the target eNB. 47. The method of claim 46, wherein the RRC message comprises an RRC Connection Change Command message. 48. The method of claim 47, further comprising: A top-level information element (IE) is received from the target eNB to facilitate setting the configuration in the RRC connection change command message. 49. The method of claim 40, wherein the measurement report includes information about current radio conditions at the UE. 50. The method of claim 40, further comprising: selecting a target eNB at the source eNB for handing over the UE based on the measurement report; and Wherein, the handover request message includes UE context information; The handover request confirmation message includes a transparent container, wherein the transparent container indicates a radio configuration for the UE at the target eNB; and The forwarding step further includes: forwarding the transparent container from the source eNB to the UE in an RRC connection change message. 51. The method of claim 50, wherein the source eNB communicates according to a first protocol version or a first radio configuration, and the target eNB communicates according to a second protocol version or a second radio configuration different from the source eNB. 52. The method of claim 50, wherein the source eNB maintains coupling between a mobile tunnel and a radio bearer for the UE. 53. The method of claim 50, wherein the transparent container includes a delta configuration with changes made to the UE context information. 54. An apparatus for performing an enhanced Node B (eNB) inter-handover, comprising: means for receiving, at a source eNB, a measurement report from a user equipment (UE), wherein the measurement report includes information regarding a preferred target eNB; A module for sending a handover request message from a source eNB to a target eNB; means for receiving a handover request confirm message from the target eNB, the handover request confirm message including a configuration required by the target eNB for the UE related to the handover, the handover request confirm message being designed to enable the source eNB to forward the configuration to the UE, wherein the source eNB does not have access to the configuration; and Means for forwarding the configuration from the source eNB to the UE. 55. The apparatus of claim 54, wherein the configuration comprises an incremental configuration comprising one or more changes specified by the target eNB. 56. The apparatus of claim 55, wherein the incremental configuration is generated based on a comparison, performed at the target eNB, between a current configuration and a new configuration of the UE associated with the target eNB. 57. The apparatus of claim 54, further comprising: Means for receiving a transparent container as part of the handover request acknowledgement, the transparent container including the configuration determined by the target eNB. 58. The apparatus of claim 57, wherein the transparent container includes configuration parameters specified by the target eNB for changing a current configuration of a UE to facilitate the handover to the target eNB. 59. The apparatus of claim 54, wherein the means for forwarding the configuration comprises: means for setting the configuration in a radio resource control (RRC) message; and A module for sending the RRC message to the UE. 60. The apparatus of claim 59, wherein the RRC message includes reconfiguration information to facilitate mobility between the source eNB and the target eNB. 61. The apparatus of claim 60, wherein the RRC message comprises an RRC Connection Change Command message. 62. The apparatus of claim 61 , further comprising: Means for receiving a top-level information element (IE) from the target eNB to facilitate setting the configuration in the RRC connection change command message. 63. The apparatus of claim 54, wherein the measurement report includes information about current radio conditions at the UE. 64. The apparatus of claim 54, further comprising: means for selecting a target eNB at the source eNB for handover of the UE based on the measurement report; and Wherein, the handover request message includes UE context information; The handover request confirmation message includes a transparent container, wherein the transparent container indicates a radio configuration for the UE at the target eNB; and The module for forwarding further includes: a module for forwarding the transparent container from the source eNB to the UE in an RRC connection change message.