HK1138144A - Radio resource connection (rrc) establishment for wireless systems - Google Patents

Description

Radio Resource Connection (RRC) establishment for wireless systems

RELATED APPLICATIONS

Priority of U.S. provisional application No.60/884,387 entitled "RRC CONNECTIONESTABLISMISHMENT IN E-UTRAN (RRC connection establishment IN E-UTRAN)" filed on 10.1.2007, assigned to the assignee hereof, and incorporated herein by reference.

Technical Field

The following description relates generally to wireless networks, e.g., Radio Resource Connection (RRC) in wireless communication systems such as E-UTRAN.

Background

Wireless communication networks are commonly used to transmit information regardless of where the user is located and whether the user is stationary or moving. Generally, a wireless communication network is established by a mobile device (or "access terminal") that communicates with a series of base stations (or "access points").

Typically, when an access terminal moves from one location served by a first access point to a second location served by a second access point, a communication "handoff" will be performed such that the access terminal stops communicating through the first access point and begins communicating through the second access point. Although conceptually seemingly simple, such switching is often very complex and presents a number of problems in operation. For example, if the two access points in the above example are not synchronized, the access terminal may have difficulty in determining whether a second access point is present and/or determining critical information for allowing the access terminal to identify and begin communicating with the second access point.

Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the 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 lte systems, and Orthogonal Frequency Division Multiple Access (OFDMA) systems.

Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. The communication link may be established by a single-in single-out, multiple-in single-out, or multiple-in multiple-out (MIMO) system.

MIMO systems employing multiple (N)_TMultiple) transmitting antenna and multiple (N)_RAnd) receiving antennas for data transmission. By N_TA transmitting antenna and N_RThe MIMO channel formed by the receiving antennas can be decomposed into N_SIndividual channels, also called spatial channels, where N_S≤min{N_T，N_R}。N_SOne for each dimension of the individual channels. The MIMO system may provide performance improvements (e.g., higher throughput and/or greater reliability) if the additional dimensionalities created by the multiple transmit and receive antennas are utilized)。

MIMO systems support Time Division Duplex (TDD) and Frequency Division Duplex (FDD) systems. In a TDD system, forward link transmission and reverse link transmission are performed on the same frequency region, so that the reciprocity principle (reciprocity principle) allows estimation of the forward link channel from the reverse link channel. This enables an access point to extract transmit beamforming gain on the forward link when multiple antennas are available at the access point.

For FDMA-based systems, two scheduling techniques are typically employed, including: (1) subband scheduling, where user packets may be mapped onto tone allocations (tone allocations) limited to a narrow bandwidth, and may be referred to in this disclosure as Frequency Selective Scheduling (FSS); and (2) Diversity Scheduling, where user packets are mapped onto tone allocations across the entire system bandwidth, and may be referred to in this disclosure as Frequency Hopping Scheduling (FHS).

Frequency hopping is typically used to achieve diversity of channels and interference. From this point of view, frequency hopping within a sub-band can also be performed with FSS.

However, in a given system, all users may or may not always benefit from FSS. Therefore, it may be advantageous to employ an advantageous design in terms of hopping structure so that FSS and FHS users can be easily multiplexed within the same Transmission Time Interval (TTI). Accordingly, new techniques directed to improving handovers between cellular devices may be useful.

Disclosure of Invention

Various aspects and embodiments of the invention are described in more detail below.

In one embodiment, a method for performing a wireless handover of a User Equipment (UE) when the UE performs a handover from a source extended node-B (e-NB) to a target e-NB is disclosed. The method comprises the following steps: detecting, by the UE, a Radio Link Failure (RLF) between the UE and the source e-NB; and after detecting the RLF and while the UE performs the handover from the source e-NB to the target e-NB, maintaining valid communication services at a service layer of the UE such that the communication services continue to remain valid during the handover, the communication services supporting first communications between the UE and a third party.

In another embodiment, an article of manufacture is disclosed for a User Equipment (UE) capable of performing a handover from a source extended node-B (e-NB) to a target e-NB. The UE includes: a wireless communication circuit; means for detecting, by the UE coupled to the wireless communication circuitry, a Radio Link Failure (RLF) between the UE and the source e-NB; and means for maintaining, after detecting the RLF and while the UE performs the handover from the source e-NB to the target e-NB, a valid communication service at a service layer of the UE such that the communication service continues to remain valid during the handover, the communication service supporting a first communication between the UE and a third party.

In another embodiment, an article of manufacture is disclosed for a User Equipment (UE) capable of performing a handover from a source extended node-B (e-NB) to a target e-NB. The UE includes: detection circuitry configured to detect, by the UE, a Radio Link Failure (RLF) between the UE and the source e-NB; and communication circuitry configured to maintain an active communication service at a service layer of the UE after detecting the RLF and while the UE performs the handover from the source e-NB to the target e-NB such that the communication service continues to remain active during the handover, the communication service supporting a first communication between the UE and a third party.

In another embodiment, a computer program product comprises a computer readable medium comprising: a set of one or more instructions for determining whether a Radio Link Failure (RLF) occurs between a User Equipment (UE) and a source extended node-B (e-NB); and means for performing a wireless handover of the UE after detecting the RLF and while the UE performs the handover from the source e-NB to the target e-NB, while maintaining an active communication service at a service layer of the UE such that the communication service continues to remain active during the handover, the communication service supporting a first communication between the UE and a third party.

In another embodiment, a method for performing a wireless handover of a User Equipment (UE) when the UE performs a handover from a source extended node-B (e-NB) to a target e-NB is disclosed. The method comprises the following steps: receiving a connection request message from the UE, the connection request message received after a radio link failure of a communication link between the UE and the source e-NB; forwarding the connection request message to a core communication network; receiving a connection setup message from the core network in response to the forwarded connection request message; and forwarding the connection establishment message to the UE such that communication services active at a service layer of the UE continue to remain active during the handover while communication payload data transmission is reestablished between the UE and a third party through the target e-NB.

In another embodiment, an extended node-B (e-NB) capable of being used for handover of a User Equipment (UE) from a source extended node-B (e-NB) to a target e-NB is disclosed. The e-NB comprises: a wireless communication circuit; and processing circuitry coupled to the wireless communication circuitry, the processing circuitry configured to: receiving a connection request message from the UE, the connection request message received after a radio link failure of a communication link between the UE and the source e-NB; forwarding the connection request message to a core communication network; receiving a connection setup message from the core network in response to the forwarded connection request message; and forwarding the connection establishment message to the UE such that communication services active at a service layer of the UE continue to remain active during the handover while communication payload data transmission is reestablished between the UE and a third party through the target e-NB.

In another embodiment, an extended node-B (e-NB) is capable of being used for handover of a User Equipment (UE) from a source extended node-B (e-NB) to a target e-NB, the e-NB comprising: a wireless communication circuit; means for receiving a connection request message from the UE coupled to the wireless communication circuitry, the connection request message received after a radio link failure of a communication link between the UE and the source e-NB; means for forwarding the connection request message to a core communication network; means for receiving a connection setup message from the core communication network in response to the forwarded connection request message; and means for forwarding the connection establishment message to the UE such that communication services active at a service layer of the UE continue to remain active during the handover while communication payload data transmission is reestablished between the UE and a third party through the target e-NB.

In another embodiment, a computer program product comprises a computer readable medium comprising: receive a set of one or more instructions for receiving a connection request message from a UE coupled to wireless communication circuitry, the connection request message received after a radio link failure of a communication link between the UE and the source e-NB; a set of one or more instructions for forwarding the connection request message to a core communication network; a set of one or more instructions for receiving a connection setup message from the core communication network in response to the forwarded connection request message; and a set of one or more instructions for forwarding the connection setup message to the UE such that communication services active at a service layer of the UE continue to remain active during the handover while communication payload data transmission is reestablished between the UE and a third party through the target e-NB.

Drawings

The features and nature of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which reference characters identify corresponding items.

Fig. 1 depicts an exemplary wireless communication system with an access point and a plurality of access terminals.

Fig. 2 depicts details of an exemplary access point and an exemplary access terminal.

Fig. 3 depicts a transition of an access terminal from a first wireless cell to a second wireless cell.

Fig. 4 and 5 depict the interruption of the service layer when a radio link failure occurs.

Fig. 6 depicts a service layer interruption when a radio link failure occurs during handover.

FIG. 7 is a flowchart outlining an exemplary operation of the disclosed method and system.

Detailed Description

The disclosed methods and systems may be described below generally and in terms of specific examples and/or specific embodiments. For example, where reference is made to detailed examples and/or embodiments, it is to be appreciated that any underlying principles described are not limited to a single embodiment, but may be extended to cases for any other methods and systems described herein, as will be appreciated by one of ordinary skill in the art, unless specifically stated otherwise.

It should be appreciated that the methods and systems disclosed below may relate to mobile and non-mobile systems, including mobile phones, PDAs and laptop PCs, as well as any number of specially equipped/modified music players (e.g., modified apples) that may implement wireless communication technology) Video players, multimedia players, televisions (fixed, portable and/or vehicle), electronic game systems, digital cameras andvideo camcorders.

Referring to fig. 1, a multiple access wireless communication system in accordance with one embodiment is illustrated. An access point 100(AP) includes multiple antenna groups, one including 104 and 106, another including 108 and 110, and an additional including 112 and 114. In fig. 1, only two antennas are shown for each antenna group, however, more or fewer antennas may be utilized for each antenna group. Access terminal 116(AT) is in communication with antennas 112 and 114, where antennas 112 and 114 transmit information to access terminal 116 over forward link 120 and receive information from access terminal 116 over reverse link 118. Access terminal 122 is in communication with antennas 106 and 108, where antennas 106 and 108 transmit information to access terminal 122 over forward link 126 and receive information from access terminal 122 over reverse link 124. In a FDD system, communication links 118, 120, 124 and 126 may use different frequency for communication. For example, forward link 120 may use a different frequency than that used by reverse link 118.

Each group of antennas and/or the area in which they are designed to communicate is often referred to as a sector of the access point.

In communication over forward links 120 and 126, the transmitting antennas of access point 100 can utilize beamforming in order to improve the signal-to-noise ratio of forward links for the different access terminals 116 and 124. Furthermore, an access point using beamforming to transmit to access terminals scattered randomly through its coverage causes less interference to access terminals in neighboring cells than if the access point were transmitting through a single antenna to all its access terminals.

An access point may be a fixed station used for communicating with the terminals and may also be referred to as an access point, a Node-B, or some other terminology. An access terminal may also be called an access terminal, User Equipment (UE), a wireless communication device, terminal, access terminal, or some other terminology.

It should be appreciated that in various embodiments, the access terminal and the access point may communicate with each other using a repeating sequence (repetitive sequence) known as a superframe architecture. For example, moving briefly to fig. 5, the top data stream 500 is composed of a series of superframes, including consecutive superframes 502 and 504. Each of the superframes 502 and 504 includes a Superframe Beacon (SB)512 followed by a series of alternating Downstream (DS) frames (514, 518, and 522) and Upstream (US) frames (516, 520, and 524).

In operation, a superframe beacon 512 can be transmitted by an access point to provide important information about the access point to access terminals, including identification and synchronization information that the access terminals can use to synchronize with, establish contact with, and maintain communication with the access point. Once communication is established, the access terminal may send information to the access point over any or all US frames and receive information from the access point over any or all DS frames. It should be noted, however, that during the period of the US frame in which the access terminal is actively transmitting, the access terminal may not be able to receive data or even be aware of the presence of another transmitted signal.

Turning back to fig. 2, a block diagram of an embodiment of a transmitter system 210 (also known as an access point) and a receiver system 250 (also known as an access terminal) in a MIMO system 200 is shown. At the transmitter system 210, traffic data for a number of data streams is provided from a data source 212 to Transmit (TX) data processor 214.

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

The coded data for each data stream may be multiplexed with pilot data using OFDM techniques. The pilot data is typically a known data pattern that is processed in a known manner and may be used at the receiver system to estimate the channel response. The multiplexed pilot and coded data for each data stream is then modulated (e.g., symbol mapped) based on a particular modulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM) selected for that data stream to provide modulation symbols. The data rate, coding, and modulation for each data stream may be determined by instructions performed by processor 230.

The modulation symbols for all data streams are then provided to a TX MIMO processor 220, and the modulation symbols may be further processed (e.g., for OFDM) by the TX MIMO processor 220. TX MIMO processor 220 then passes N_TOne modulation symbol stream is provided to N_TAnd Transmitters (TMTR)222a through 222 t. In certain embodiments, 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 transmitter 222 receives and processes a respective 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. Then, from N_TN from transmitters 222a through 222t are transmitted by antennas 224a through 224t, respectively_TA modulated signal.

At the receiver system 250, by N_RThe transmitted modulated signals are received by antennas 252a through 252r and the received signal from each antenna 252 is provided to a respective receiver (RCVR)254a through 254 r. Each receiver 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.

RX data processor 260 then receives and processes the secondary N based on a particular receiver processing technique_RN received by receiver 254_RA stream of symbols to provide N_TA stream of "detected" symbols. 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 RX data processor 260 is complementary to that performed by TX MIMO processor 220 and TX data processor 214 at transmitter system 210.

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

Generally, the processors 230 and 270 of FIG. 2 will be responsible for all formatting of the various symbol/data streams to and from each other. That is, the example processors 230 and 270 of fig. 2 are central to performing the functions of a Media Access Controller (MAC) (depicted as MAC 231 and MAC 271, respectively), and thus, may be responsible for forming all of the communication structures discussed above with reference to fig. 5 and discussed below with reference to fig. 5-8.

The reverse link message may comprise various information regarding the communication link and/or the received data stream. The reverse link message is then processed by a TX data processor 238, which also receives traffic data for a number of data streams from a data source 236, modulated by a modulator 280, conditioned by transmitters 254a through 254r, and transmitted back to transmitter system 210.

At transmitter system 210, the modulated signals from receiver system 250 are received by antennas 224, conditioned by receivers 222, demodulated by a demodulator 240, and processed by a RX data processor 242 to extract the reserve link message transmitted by receiver system 250. Processor 230 then determines which pre-coding matrix to use for determining the beamforming weights then processes the extracted message.

In one aspect, logical channels are divided into control channels and traffic channels. The logical control channels include: a Broadcast Control Channel (BCCH) which is a DL channel for broadcasting system control information; a Paging Control Channel (PCCH), which is a DL channel that transmits paging information; and a Multicast Control Channel (MCCH) which is a point-to-multipoint DL channel used for transmitting Multimedia Broadcast and Multicast Service (MBMS) scheduling and control information for one or several MTCHs. Typically, this channel is only used by UEs receiving MBMS (note: MCCH + MSCH in the past) after RRC connection is established. Dedicated Control Channel (DCCH) is a point-to-point bi-directional channel that transmits dedicated control information and is used by UEs having an RRC connection. In one aspect, the logical traffic channels may include: a Dedicated Traffic Channel (DTCH), which is a point-to-point bi-directional channel dedicated to the transmission of user information for one UE. In addition, a Multicast Traffic Channel (MTCH) for a point-to-multipoint DL channel is used to transmit traffic data.

In one scheme, a Transport Channel (Transport Channel) is divided into DL and UL. DL transport channels include a Broadcast Channel (BCH), downlink shared data channel (DL-SDCH) and a Paging Channel (PCH), the PCH for support of UE power saving (DRX cycle is indicated to the UE by the network), broadcasted throughout the cell and mapped to PHY resources that can be used for other control/traffic channels. The UL transport channels include a Random Access Channel (RACH), a request channel (REQCH), an uplink shared data channel (UL-SDCH), and a plurality of PHY channels. The PHY channels include a set of DL channels and UL channels.

The DL PHY channels may include: common pilot channel (CPICH), Synchronization Channel (SCH), Common Control Channel (CCCH), Shared DL Control Channel (SDCCH), Multicast Control Channel (MCCH), Shared UL Allocation Channel (SUACH), acknowledgement channel (ACKCH), DL physical shared data channel (DL-PSDCH), UL Power Control Channel (UPCCH), Paging Indicator Channel (PICH), and Load Indicator Channel (LICH).

The UL PHY channels may include: a Physical Random Access Channel (PRACH), a Channel Quality Indication Channel (CQICH), an acknowledgement channel (ACKCH), an Antenna Subset Indication Channel (ASICH), a shared request channel (SREQCH), a UL physical shared data channel (UL-PSDCH), and a broadcast pilot channel (BPICH).

In one aspect, a channel structure is provided that preserves the low PAR (the channel is continuous or equidistant in frequency at any given moment) property of a single carrier waveform.

Referring to fig. 3, illustrated is a wireless communication system 300 that provides multiple access in accordance with an aspect. The multiple access wireless communication system 300 includes a plurality of cells, including cells 302, 304, and 306. In the arrangement of fig. 3, each cell 302, 304, and 306 may include an access point that includes multiple sectors. The multiple sectors may be formed by groups of antennas each responsible for communication with access terminals in a portion of the cell. For example, in cell 302, antenna groups 312, 314, and 316 may each correspond to a different sector. In cell 304, antenna groups 318, 320, and 322 may each correspond to a different sector. In cell 306, antenna groups 324, 326, and 328 may each correspond to a different sector.

Each cell 302, 304, and 306 may include a number of wireless communication devices, such as user equipment or access terminals, which may communicate with one or more sectors of each cell 302, 304, or 306. For example, access terminals 330 and 332 can communicate with access point 342, access terminals 334 and 336 can communicate with access point 344, and access terminals 338 and 340 can communicate with access point 346.

If one of the access terminals moves from its corresponding sector, its communication with the corresponding access point associated with that sector may deteriorate. For example, if access terminal 334 moves from sector 304, its communication capabilities with access point 344 may deteriorate as access terminal 334 moves away from access point 344.

In this example, the access terminal 334 is depicted in fig. 4 as moving toward the cell 306 (at 334). In this case, the access terminals 334-334' may get better service if it establishes communication with the access point 346 in the cell 306. For ease of description, this process will be referred to as a "handoff" from an established access point to a target access point.

In a handover from cell 304 to cell 306, information regarding access terminals 334-334' may be sent to target access point 346 through established access point 344. Such data transfer can expedite access to the target access point 346. Similarly, the target access point 346 can transmit specific data to the access terminals through the established access point 344, including timing/synchronization data, and data related to any resources provided by the target access point 346 to the access terminals 334-334'.

The 3GPP LTE (long term evolution) is the name given to an item in the third generation partnership project that improves the Universal Mobile Telecommunications System (UMTS) mobile phone standard to cope with future requirements. In evolved universal terrestrial radio access network (E-UTRAN), RRC connection establishment is accomplished through LTE _ IDLE state. The network needs to distinguish the state transition for RRC connection establishment from the normal state transition from LTE _ IDLE to LTE _ ACTIVE. The present disclosure provides a new method of enabling the network to make such a distinction.

Fig. 4 depicts a communication system experiencing a disruption of the service layer in the event of a radio link failure. As shown in fig. 4, the communication system includes a UE 410 and a supporting communication network 420, the UE 410 having a service layer 412 and a protocol layer 414, and the network 420 having its own service layer 422 and protocol layer 424.

In operation, the communication system is shown to experience a Radio Link Failure (RLF) when two independent timers T2 and T2' serve the UE 410 and the network 420, respectively. Typically, RLF is detected/determined using any number of measures, such as low signal strength, unsuccessfully received packets, bit errors, etc. The RLF on the network side is identified by a similar procedure or by receiving some upstream signal sent by the UE 410.

When the timer T2 expires, the protocol layer 414 of the UE transitions from the LET _ ACTIVE state to the LTE _ IDLE state while the service layer changes from ACTIVE to inactive. A similar transition occurs on the network side when timer T2' (typically longer than timer T2) expires.

Note that when the respective service layers 412 and 424 become inactive, the communication signals served by the service layers 412 and 424 will no longer persist, and subsequent re-establishment of radio signals may require re-activation of the service layers 412 and 424. In this de-activation case, the user will experience a service interruption.

For newly developed wireless communication systems, such as E-UTRAN, the current working premise is that UE-controlled mobility can be implemented over LTE _ IDLE without causing application layer service disruption.

As depicted in fig. 5, on UE-controlled mobility, the UE protocol layer 414 may not indicate a connection release to the service layer 412. However, this may be achieved by the protocol layer 414 having the concept of "reestablishment substate (re-establishment state)" in the LTE _ IDLE state. The RRC context may not be reallocated in UE controlled mobility, therefore, the RRC may enter the RRC IDLE state during this sub-state, and the NAS layer in the UE may have to manage this sub-state.

In this re-establishment sub-state, the NAS layer in the UE maintains the current state of the service. Further, the MME/UPE may not release the UE's operational context so that the service and corresponding SAE access bearer (access bearer) may proceed after the temporary LTE _ IDLE state.

Fig. 6 depicts the service layer interruption when a radio link failure occurs during which the UE 610 is handed over from a source e-NB (not shown) to a target e-NB 612, which in turn is supported by the MME/UPE (for this example, its supporting core network). Note that for this example, all communication links may be enabled by any number of wired and wireless communication links supported by any number of communication circuit modules, processors, software, etc.

Fig. 7 is a flowchart outlining an exemplary communication re-establishment operation for the communication system of fig. 6. Note that the communication system and various operations allow for the efficient communication services of the UE 610 and third parties at the service layer to be maintained while RLF occurs between the UE 610 and the source e-NB (still not shown). Accordingly, the UE 610 may perform a handover to the target e-NB 612 so that communication services may continue to remain active during the handover. For example, the UE 610 may receive some form of media delivery, such as receiving a real-time movie and/or accepting an interactive voice service (e.g., a telephone call), with only a minor interruption in service. Unlike previously known methods and systems, no service interruption necessarily occurs.

The process starts in step 702, and RLF is detected in step 702, so that communication services between the source e-NB and the UE and third parties supported by the core network may be interrupted. For example, assuming that the UE is receiving a real-time news broadcast, the sound at the UE may cease upon the occurrence of RLF. Next, in step 704, the UE may detect a target e-NB, such as target e-NB 612 of fig. 6. Control continues to step 706.

In step 706, the UE may transition from the active state to a special idle state/re-establishment sub-state while sending a connection request message to the target e-NB. Note that unlike previous techniques, such idle state/reestablishment substates may not require the UE's respective service layer to cease operation of the connection service. That is, even if payload data of the communication service is not available, the underlying processing supporting the communication can continue. Note that the connection request message to the target e-NB may include information related to maintaining a valid communication service, such as a flag indicating that the UE is going into a service re-establishment sub-state rather than aborting operation of the service layer.

In step 708, the connection request message may be received by the target e-NB and forwarded by the target e-NB to the core communication network. Next, in step 710, the forwarded connection request message may be received by the core network, and as a result, the core network may transition from the active state to its own modified idle state/re-establishment sub-state. Then, in step 712, the core network may perform lower layer processing for reestablishing communication in compliance with the handover. Control continues to step 714.

In step 714, the core network may send an appropriate connection setup message/request to the target e-NB and exit its modified idle state/re-establishment sub-state to enter the active state again. Next, in step 716, the connection setup message may be received by the target e-NB and forwarded by the target e-NB to the UE. The UE may then receive the connection setup message and exit its modified idle state/re-establishment sub-state to enter the active state again in step 718. Control continues to step 720.

In step 720, communication between the UE and the appropriate third party may be resumed, i.e., payload data is again efficiently transmitted, and control continues to step 750, where processing stops.

It is to be understood that the specific order or hierarchy of steps in the processes disclosed is an example of exemplary arrangements. It should be understood that the specific order or hierarchy of steps in the processes may be rearranged based on design preferences while remaining within the scope of the present invention. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

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

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (37)

1. A method for performing a wireless handover of a User Equipment (UE) when the UE performs a handover from a source extended node-B (e-NB) to a target e-NB, the method comprising:

detecting, by the UE, a Radio Link Failure (RLF) between the UE and the source e-NB; and

maintaining, after detecting the RLF and while the UE performs the handover from the source e-NB to the target e-NB, an active communication service at a service layer of the UE such that the communication service continues to remain active during the handover, the communication service supporting a first communication between the UE and a third party.

2. The method of claim 1, wherein the communication service comprises at least one of a media delivery service and an interactive voice service.

3. The method of claim 2, further comprising: after detecting the RLF, detecting the target e-NB.

4. The method of claim 2, further comprising: sending a connection request message to the target e-NB.

5. The method of claim 4, wherein the connection request message sent to the target e-NB comprises first information related to maintaining the active communication service.

6. The method of claim 5, wherein the first information comprises a flag indicating that the UE is to enter a service re-establishment sub-state.

7. The method of claim 6, wherein the connection request message sent to the target e-NB is forwarded by the target e-NB to a core communication network, and the core communication network provides a connection setup message to the target e-NB in response to the forwarded connection request message.

8. The method of claim 7, further comprising: receiving a forwarded connection setup message from the target e-NB.

9. The method of claim 7, further comprising: resuming, by the target e-NB, transmission of payload data of the first communication between the UE and the third party.

10. An article of manufacture of a User Equipment (UE) capable of performing a handover from a source extended node-B (e-NB) to a target e-NB, the UE comprising:

a wireless communication circuit;

means for detecting, by the UE coupled to the wireless communication circuitry, a Radio Link Failure (RLF) between the UE and the source e-NB; and

means for maintaining, after detecting the RLF and while the UE performs the handover from the source e-NB to the target e-NB, an active communication service at a service layer of the UE such that the communication service continues to remain active during the handover, the communication service supporting a first communication between the UE and a third party.

11. The product of claim 10, wherein the communication service comprises at least one of a media delivery service and an interactive voice service.

12. The product of claim 11, further comprising: means for transmitting a connection request message to the target e-NB, wherein the connection request message transmitted to the target e-NB includes first information related to maintaining the active communication service.

13. The product of claim 12, further comprising: means for receiving a forwarded connection setup message from the target e-NB, wherein a core communication network provides a first connection setup message to the target e-NB in response to a connection request message forwarded from the target e-NB, the forwarded connection setup message generated in response to the core communication network providing the first connection setup message.

14. An article of manufacture of a User Equipment (UE) capable of performing a handover from a source extended node-B (e-NB) to a target e-NB, the UE comprising:

detection circuitry configured to detect, by the UE, a Radio Link Failure (RLF) between the UE and the source e-NB; and

communication circuitry configured to maintain an active communication service at a service layer of the UE after detecting the RLF and while the UE performs the handover from the source e-NB to the target e-NB such that the communication service continues to remain active during the handover, the communication service supporting a first communication between the UE and a third party.

15. The product of claim 14, wherein the communication service comprises at least one of a media delivery service and an interactive voice service.

16. The product of claim 15, wherein the communication circuitry is further configured to transmit a connection request message to the target e-NB, wherein the connection request message transmitted to the target e-NB includes first information related to maintaining the active communication service.

17. The product of claim 16, wherein the communication circuitry is further configured to receive a forwarded connection setup message from the target e-NB, wherein a core communication network provides a first connection setup message to the target e-NB in response to a forwarded connection request message from the target e-NB, the forwarded connection setup message generated in response to the core communication network providing the first connection setup message.

18. A computer program product, comprising:

a computer-readable medium comprising:

a set of one or more instructions for determining whether a Radio Link Failure (RLF) occurs between a User Equipment (UE) and a source extended node-B (e-NB); and

one or more sets of instructions for performing a wireless handover of the UE while maintaining an active communication service at a service layer of the UE after detecting the RLF and when the UE performs a handover from the source e-NB to the target e-NB, such that the communication service continues to remain active during the handover, the communication service supporting a first communication between the UE and a third party.

19. The computer program product of claim 18, wherein the communication service comprises at least one of a media delivery service and an interactive voice service.

20. The computer program product of claim 18, further comprising:

a set of one or more instructions for transmitting a connection request message to the target e-NB, wherein the connection request message transmitted to the target e-NB includes first information related to maintaining the active communication service.

21. The computer program product of claim 20, further comprising:

a set of one or more instructions for receiving a forwarded connection setup message from the target e-NB, wherein a core communication network provides a first connection setup message to the target e-NB in response to a forwarded connection request message from the target e-NB, the forwarded connection setup message generated in response to the core communication network providing the first connection setup message.

22. A method for performing a wireless handover of a User Equipment (UE) when the UE performs a handover from a source extended node-B (e-NB) to a target e-NB, the method comprising:

receiving a connection request message from the UE, the connection request message received after a radio link failure of a communication link between the UE and the source e-NB;

forwarding the connection request message to a core communication network;

receiving a connection setup message from the core network in response to the forwarded connection request message; and

forwarding the connection setup message to the UE such that valid communication services at a service layer of the UE continue to remain valid during the handover while communication payload data transmission is reestablished between the UE and a third party through the target e-NB.

23. The method of claim 22, wherein the communication service comprises at least one of a media delivery service and an interactive voice service.

24. The method of claim 22, wherein the connection request message to the target e-NB includes first information related to maintaining the active communication service.

25. The method of claim 24, wherein the first information comprises a flag indicating that the UE is to enter a service re-establishment sub-state.

26. An extended node-B (e-NB) capable of being used for handover of a User Equipment (UE) from a source extended node-B (e-NB) to a target e-NB, the e-NB comprising:

a wireless communication circuit;

processing circuitry coupled to the wireless communication circuitry, the processing circuitry configured to:

receiving a connection request message from the UE, the connection request message received after a radio link failure of a communication link between the UE and the source e-NB;

forwarding the connection request message to a core communication network;

receiving a connection setup message from the core communication network in response to the forwarded connection request message; and

forwarding the connection setup message to the UE such that valid communication services at a service layer of the UE continue to remain valid during the handover while communication payload data transmission is reestablished between the UE and a third party through the target e-NB.

27. The method of claim 26, wherein the communication service comprises at least one of a media delivery service and an interactive voice service.

28. The method of claim 26, wherein the connection request message to the target e-NB includes first information related to maintaining the active communication service.

29. The method of claim 28, wherein the first information comprises a flag indicating that the UE is to enter a service re-establishment sub-state.

30. An extended node-B (e-NB) capable of being used for handover of a User Equipment (UE) from a source extended node-B (e-NB) to a target e-NB, the e-NB comprising:

a wireless communication circuit;

means for receiving a connection request message from the UE coupled to the wireless communication circuitry, the connection request message received after a radio link failure of a communication link between the UE and the source e-NB;

means for forwarding the connection request message to a core communication network;

means for receiving a connection setup message from the core communication network in response to the forwarded connection request message; and

means for forwarding the connection setup message to the UE such that active communication services at a service layer of the UE continue to remain active during the handover while communication payload data transmission is reestablished between the UE and a third party through the target e-NB.

31. The method of claim 30, wherein the communication service comprises at least one of a media delivery service and an interactive voice service.

32. The method of claim 31, wherein the connection request message to the target e-NB includes first information related to maintaining the active communication service.

33. The method of claim 32, wherein the first information comprises a flag indicating that the UE is to enter a service re-establishment sub-state.

34. A computer program product, comprising:

a computer-readable medium comprising:

receive a set of one or more instructions for receiving a connection request message from a UE coupled to wireless communication circuitry, the connection request message received after a radio link failure of a communication link between the UE and a source e-NB;

a set of one or more instructions for forwarding the connection request message to a core communication network;

a set of one or more instructions for receiving a connection setup message from the core communication network in response to the forwarded connection request message; and

a set of one or more instructions for forwarding the connection setup message to the UE such that an active communication service at a service layer of the UE continues to remain active during the handover while communication payload data transmission is reestablished between the UE and a third party through the target e-NB.

35. The computer program product of claim 18, wherein the communication service comprises at least one of a media delivery service and an interactive voice service.

36. The computer program product of claim 34, wherein the connection request message to the target e-NB includes first information related to maintaining the active communication service.

37. The computer program product of claim 36, wherein the first information comprises a flag indicating that the UE is to enter a service re-establishment sub-state.