GB2493605A

GB2493605A - E-UTRAN cell measurements and (re)selection during radio resource control state transitions

Info

Publication number: GB2493605A
Application number: GB1212491.3A
Authority: GB
Inventors: Steven Franklin; James Howard Tooley; Brian Alexander Martin; Christopher Peter Callender; Stuart Ian Geary; Alexander Graham Charles
Original assignee: Renesas Mobile Corp
Current assignee: Renesas Electronics Corp
Priority date: 2012-07-13
Filing date: 2012-07-13
Publication date: 2013-02-13
Anticipated expiration: 2032-07-13
Also published as: GB201212491D0; GB2493605B

Abstract

A User Equipment, UE, performs cell measurement and evaluation 64 on another frequency or system during a Radio Resource Control, RRC, state transition from a first state 52 to a second state 54, where a cell measurement is not normally possible in the first and second states. Cell measurement and evaluation is performed during a transition to a CELL_FACH state to identify a suitable E-UTRAN cell for possible cell reselection. UE camped in UTRAN connected state, receives a Radio Bearer Reconfiguration message and disconnects from the network to perform reconfiguration 56. The UE performs cell selection 58 and camps on a cell and monitors the FACH 60. As the UE is disconnected from the network it has more time to perform cell measurements and evaluation 64 on Long Term Evolution, LTE, frequencies to search and find a suitable E-UTRAN cell 66. Prior to performing cell measurement and evaluation, measurement conditions 62 may need to be satisfied, including: determining that measurement occasions are not available in the CELL_FACH state, determining that discontinuous reception is not available in the CELL_FACH state, determining that CELL_FACH measurements to LTE is not enabled, or, determining that there is suitable coverage on another frequency or system.

Description

METHOD, APPARATUS AND COMPUTER PROGRAM

FOR CELL MEASUREMENTS AND EVALUATTON

Technical Field

The present invention relates to the field of wireless communications.

Particular examples relate to a system and method for E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) measurements and cell selection (and reselection) during RRC (Radio Resource Control) state transitions.

Backizround The following abbreviations which may be found in the specification and/or thc drawing figures are deflncd as follows: DCH Dedicated Channel DRX Discontinuous reception ELI E-UTRAN Layer 1 eNodeB Evolved Node B E-UTRAN Evolved Universal Terrestrial Radio Access Network FACH Forward Access Channel LT[ Long Term Evolution MME Mobility Management Entity NW Network PCH Physical Channel RANC Radio Access Network Control RAT Radio Acccss Technology RRC Radio Resource Control SCCPCH Secondary Common Control Physical Channel STB System Tnformation Block UE User Equipment UMTS Universal Mobile Telecommunications System UTRAN UMTS Terrestrial Radio Access Network WCDMA Widcband Code Division Multiple Access WLI WCDMA Layer 1 WTRIJ Wireless Transmit/Receive Unit The Third Generation Partnership Project (3GPP) unites six telecommunications standards bodies, known as "Organisational Partners", and provides their members with a stable environment to produce the highly successful Reports and Specifications that define 3GPP technologies. A mobile device, also called a User Equipment (DIE), may operate in a wireless communication nctwork that provides high-speed data and/or voice communications. The wireless communication networks may implement circuit-switched (CS) and/or packet-switched (PS) communication protocols to providc various services. For example, the UE may operate in accordance with one or more of Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, Single-Carrier FDMA (SC-EDMA) networks, etc. The terms "networks" and "systems" are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA: includes Widcband-CDMA (W-CDMA) and Low Chip Rate (LCR). cdma2000 covers IS-2000, 15-95 and 15-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM). An OFDMA network may implement a radio technology such as Evolved UTRA (E- UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, Flash-OFDM®, etc. UTRA, E-UTRA, and GSM are part of Universal Mobile Telecommunication 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 organisation named "3rd Generation Partnership Project" (3GPP). cdma2000 is described in documents from an organisation named "3rd Generation Partnership Project 2" (3GPP2). These various radio technologies and standards are known in the art.

LTE (Long Term Evolution) is a new standard for wireless communication of high-speed data for mobile phones and data terminals. It is based on the GSM/EDGE and IJMTS/HSPA (Universal Mobile Telecommunication System/High Speed Packet Access) network technologies, increasing the capacity and speed using new modulation techniques. The LTE standard was first specified in the 3GPP Release 8 document series. The IP-based LTE network architecture, called the Evolved Packet Core (EPC), supports seamless handovers for both voice and data to cell towers with older network tcchnology such as GSM, UMTS and CDMA2000. The LTE technology is adaptcd for a smooth evolution from carlier 3GPP systems.

These technologies are constantly evolving through what have become known as "gcncrations" of commercial cellular/mobile systcms. 3GPP also uses a systcm of parallel "releases" to provide developers with a stable platform for implementation and to allow for the addition of new features required by the market. Each release includes specific functionality and features that are specified in detail by the version of the 3GPP standards associated with that release, One area of focus for the 3GPP standard for LTE systems involves cell selection and reselection by which a mobile device selects a particular coverage area serviced by a base station (eNodeB) from other cells.

Summary

According to a first aspect of the present invention, there is provided a method for use in a user equipment, the method comprising performing cell measurement and evaluation on another frequency or system during a transition from a first statc to a second state, where a cell measurement is not normally possible in the first and second states.

According to a second aspect of the present invention, there is provided apparatus comprising a processing system for a wireless communication device constructed and arranged to perform cell measurement and evaluation on another frequency or system during a transition from a first state to a second state, where a cell measurement is not normally possible in the first and second states.

The processing system may comprise a memory adapted to store computer instructions, and a processor coupled to the memory and adapted to execute the computer instructions to perform as described above.

According to a third aspect of the present invention, there is provided a computer program comprising instructions that cause a wireless communications device to perform the steps of: performing cell measurement and evaluation on another frequency or system during a transition from a first state to a second state, where a cell measurement is not normally possible in the first and second states.

There may be provided a computer-readable medium having encoded thereon instructions as described above.

Thus, in examples of embodiments of the present invention, the cell measurement and evaluation on another frequency or system during a transition from a first state to a second state is carried out in the ease that a cell measurement is not possible in the first and second states. By "normally possible" mentioned above is meant that a cell measurement is not possible at all in the first and second states, or that a cell measurement might in theory or in principle be possible in the first and second states (for example, because it is provided for by Standards or technical specifications) but it may not be possible or available at a particular time for some reason, examples of which are given below.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments of the invention, given by way of example only, which is made with reference to the accompanying drawings.

Brief Description of the Drawings

FIG. 1 shows a simplified block diagram of an Evolved Packet System (EPS) architecture 10; S FIG. 2 shows a simplified state diagram of RRC (Radio Resource Control) states and transition between the states; FIG. 3 shows a simplified flowchart of an exemplary embodiment of a method of E-UTRAN cell measurement and selection during RRC state transition; FIG. 4 shows a simplified call flow diagram of an exemplary embodiment of the method shown in FIG. 3; FIG. 5 shows a simplified flowchart of an exemplary embodiment of another method of E-UTRAN cell measurement and selection during RRC state transition; FIG. 6 shows a simplified call flow diagram of an exemplary embodiment of the method shown in FIG. 5; and FIG. 7 shows a simplified block diagram of an exemplary embodiment of a WTRU (Wireless Transmit/Receive Unit).

Detailed Description

FIG. 1 is a simplified block diagram of an Evolved Packet System (EPS) architecture I 0. As shown, the User Equipment (UE) I 2 is operable to interface with and be serviced by a number of networks, including UTRAN (IJMTS Terrestrial Radio Access Network) 14, GERAN (GSM/EDGE Radio Access Network) 16, and E-UTRAN (Evolved-TRAN) 18 of the LTE system. To support circuit switched services, a connection to the Mobile Switching Center (MSC) server 20 is available.

The Mobility Management Entity (MME) node 22 of the Evolved Packet System interfaces with the MSC server via an interface called the SGs interface 24.

FIG. 2 is a simplified UE state diagram 30 of RRC (Radio Resource Control) states and transition between the states. The state diagram 30 shows the RRC states in UTRA (Universal Terrestrial Radio Access) RRC Connected Mode 32, including transitions between UTRA RRC Connected Mode 32 and GSM Connected Mode 34 for CS (Circuit-Switched) domain services, and between UTRA RRC Connected Mode 32 and GSM/GPRS Packet Modes 36 or E-UTRA RRC Connected Mode 38 for PS (Packet-Switched) domain services. It also shows the transitions between Idle Mode 40 and UTRA RRC Connected Modc 32 and furthermore thc state transitions within the UTRA RRC Connected Mode 32.

A User Equipment 12 is in the RRC Connected Mode when the RRC layer of the User Equipment and the RRC layer of a corresponding RNC are connected, such that hi-directional transfer of RRC messages are transmitted and received. If there is IS no RRC connection, the User Equipment 12 is said to be in the RRC Idle Mode 40.

Upon power-up, the User Equipment 12 is in the Idle Mode 40 by default, and it transitions to RRC Connected Mode 32 via RRC connection procedures. An RRC connection is established, for example, when uplink data transfer is needed to make a CS voice call, PS data transfer, or for registration. The RRC connection connects the User Equipment 12 to the RNC of the UTRAN 14.

As shown in FIG. 2, the UTRA RRC Connected Mode 32 includes four states: the URA PCH (UTRAN Registration Area Paging Channel) state 42, CELL PCH (CELL Paging Channel) state 44, CELL EACI-1 (CELL Forward Access Channel) state 46, and CELL DCH (CELL Dedicated Channel) state 48. Depending on the state, the User Equipment 12 is configured to perform a variety of actions and monitors different paging, common, arid dedicated channels. The RRC states within the UTRA RRC Connected Mode reflect the level of User Equipment connection and which transport channels can be used by the User Equipment. In the URA PCH 42 or CELL_PCH 44 state, the User Equipment 12 typically performs a number of functions, such as maintaining up-to-date system information that is broadcast by the sewing cell, selecting and reselecting cells, and periodically searching for higher priority PLMINs (Public Land Mobile Networks).

Based on WTRU mobility and activity while in UTRA RRC connected mode (i.e. in the CELL DCH, CELL FACH, URA PCH or CELL PCH state), the UMTS Terrestrial Radio Access Network (UTRAN) may direct the WTRU to transition between the states CELL PCI-I, URAPCH, CELL EACH, and CELL DCI-l.

Communication between the WTRU and the UTRAN, known as user plane communication, is performed while in the CELL FACH state or the CELL_DCH state.

Aflcr power on, the User Equipment stays in Idle Mode until it transmits a request to establish an RRC Connection. In Idle Mode, the connection of the User Equipment is closed on all layers of the access stratum. In Idle Mode, the User Equipment is identified by non-access stratum (NAS) identities such as IJYISI, TN4SI and P-TMSI. In addition, the UTRAN has no information about the individual Idle Mode User Equipment, and it can only address, e.g. all User Equipment in a cell or all User Equipment that are monitoring a paging occasion. The UTRA RRC Connected Mode 32 is entered by the User Equipment when the RRC Connection is established.

The User Equipment is assigned a radio network temporary identity (RNTI) to be used as User Equipment identity on common transport channels. When the User Equipment receives a message from the network that confirms that the RRC connection has been established, the User Equipment enters the CELL FACH 46 or CELL DCH 48 state of the UTRA RRC Connected Mode 32. In the case of a failure to establish the RRC Connection, the User Equipment goes back to the Idle Mode 40.

Possible causes for a failed RRC connection include radio link failure, a received reject response from the network, or lack of response from the network (timeout).

Packet data service users in a UMTS network must be in the Cell DCH (dedicated channel) or Cell EACH (forward access channel) state to transmit data. In the Cell DCH state, the user is provided with a dedicated channel (DCH) with a fixed

S

data rate. In the Cell FACH state the user shares the forward access channel (FACH) with other users. The data rate available to a user in the Cell DCH is much higher than that available in the Cell FACH state. However, due to limitations in the number of available orthogonal codes and transmit power, the number of users that can be kept in Cell DCH state is limited. This number depends on the data rate per user.

In the CELL DCI-1 state, the User Equipment is allocated a dedicated channel in both the uplink and downlink directions, and the User Equipment is known on a cell level according to its current active set. An active set is a set of radio links simultaneously involved in a specific communication service between the WTRU and the UTRAN. The WTRIJ may usc dedicated transport channels, shared transport channels, or a combination of these transport channels. A dedicated channel provides a user with a fixed data rate for transmission. Typical data rates available on the dedicated channel are 64 kb/s. 128 kb/s, and 384 kb/s. The amount of bandwidth on the DCH may be changed to accommodate fluctuations in power required (due to fading/noise conditions). It is preferable for a user to be in the Cell DCH state when transferring a large amount of data, for example when the user is surfmg the Web or streaming video.

A WTRTJ is in the CELL FACH state if it has been assigned to use the common channels (i.e. forward access channel (FACH) and random access channel (RACH)). In the CELL FACH state, no dedicated physical channel is allocated to the WTRU, which allows for better power consumption, though at the expense of a lower uplink and downlink throughput. Downlink communication in the CELL FACH state may be achieved through a shared transport channel (i.e. FACH) mapped to a shared common control physical channel (S-CCPCH). Downlink communication in the CELL FACH state may also be achieved through a high speed downlink shared channel (HS-DSCH). The WTRU continuously monitors the FACH channel, carried over the S-CCPCH, or the I-IS-DSCH, in the downlink. Uplink communication in the CELL_EACH state is achieved through a default common or shared transport channel (i.e. RACH) mapped to the EACH physical channel (PRACH), which the WTRU may use any time according to the access procedure for that transport channel. The RACH channel is a contention-based channel with a power ramp-up procedure to acquire the channel and to adjust transmit power. The position of the WTRU is known by the UTRAN on a cell level according to the cell where the WTRU last performed a cell update.

Characteristics of the CELL EACH state include being well-suited for applications requiring very low uplink throughput. Another characteristic of the CELL FACH state includes being wcll-suitcd for signalling traffic, such as transmission of CELL UPDATE messages and URA UPDATE messages. Mobility in thc CELL_EACH state is handled autonomously by the WTRU. The WTRIJ independently takes measurements and determines which cell to camp on. System information (SI), read from the broadcast channel (BCH), includes setup details for the uplink channel (RACH) and the downlink channels (EACH and HS-DSCH) to be used in the CELL EACH state.

The User Equipment monitors the broadcast channel and system information on BCCI-I (broadcast control channel) of its own and neighbouring cells, and from this observation the need for the updating of cell location is determined. In particular, data associated with networks neighbouring the PLMN currently scrving thc UE from a base station (BS) of the PLMN currently serving the User Equipment, commonly called a neighbour cell list, is broadcast to the User Equipment.

The User Equipment performs cell rcselcction and, upon selecting a new UTRA cell, initiates a cell update procedure. Upon selecting a new cell belonging to another radio access system, the User Equipment enters idle mode and tunes to its control channel. This process is known as "camping on the cell". The User Equipment, if necessary, registers its presence by means of a NAS (Non-Access Stratum) registration procedure in the registration area of the chosen cell and the selected PLMN becomes the registered PLMIN. If the User Equipment finds a more suitable cell, it reselects onto that cell and camps on it. If the new cell is in a different registration area, location registration is performed.

Currently, 3GPP Release 8 provides for cell measurement and selection from UMTS to EUTRAN in the idle mode, and in the CELL PCH and URA PCH states.

However, the standards do not specify such cell measurement and (re)selection in the CELL_EACH state. Although later reLeases such as Release Il may provide for ccli measurement and selection in the CELL EACH state, it still may not be normally possible to perform E-UTRAN measurement in this state even if thc User Equipment supports it. Some networks may not support or enable FACH Measurement Occasions (FMO) and some networks may not use Discontinuous Reception (DRX) in thc CELL FACH state. For example, when some LJscr Equipment frequently change to and from the CELL_FACH state because of the bursty nature of data transmission and reception, cell measurement and selection to E-UTRAN may not be performed.

As another example, the User Equipment may stay in the CELL_FACE state for longer periods of time after transmitting or receiving data in the CELL DCH state, leaving no opportunity to perform measurement and reselection. Even if the Release 11 feature is enabled, if there are no FACH Measurement Occasions or DRX in CELLEACH, E-U'TRAN measurement and reselcction cannot be performed in CELL_FACH. For networks that do not support the CELL PCH state, the User Equipment does not have any opportunity to perform cell reselection measurement, and may become "stuck" in UMTS even when there is suitable and preferred LTE coverage. This problem is addressed by the examples of the system and method described herein.

FIG. 3 is a simplified flowchart of an exemplary embodiment of a method 50 of E-U'TRAN cell measurement and reselection. In block 52, the User Equipment has camped on the cell in IJTRAN and is in a CELL DCH state, for example. In block 54, the User Equipment begins transition or reconfiguration from the CELL_DCH state to the CELL FACH state in response to, for example, a Radio Bearer Reconfiguration message received from the network. Upon receiving the Radio Bearer Reconfiguration message, the User Equipment disconnects from the network to perform the reconfiguration, as shown in block 56. Tn block 58, the User Equipment performs cell selection, in block 60, the User Equipment camps on a cell and monitors the FACH. Thereafter in block 62, a determination is made as to S whether cell reselection to E-TJTRAN should be performed. For example, cell reselection may be limited to the User Equipment that has been suitably camped on LTE to ensure that suitable LTE coverage is present. In addition or in the alternative, this cell reselection process may be limited to only circumstances when FACH Measurement Occasions or DRX are not available. Another limitation may be when CELL FACH measurement to LTE is not enabled. This knowledge may be obtained from the System Information Blocks received from the serving ccli. Another way to limit the performance of this cell reselection procedure is to permit it only when a certain RF fingerprint matches a known LTE coverage area, when certain data patterns are detected such as bursty data transmission/reception, etc. These are examples of criteria that may be employed separately or together to limit or control the cell measurement and reselection method disclosed herein.

If E-UTRA.N measurement criteria are met as determined in block 62, then in block 64 cell measurement of available E-UTRAN cell or frequencies is performed.

An evaluation to determine whether a suitable E-UTRAN cell is available is performed in block 66. This may be a "fast" measurement and evaluation that involves a quick sean of known LTE frequencies, which is typically a relatively small number. A number of predetermined criteria are used to determine whether an E-IX[RAN cell is suitable and is not the focus of this disclosure. In block 68, if a suitable E-UTRAN cell is available, then the User Equipment performs a cell resclection procedure and selects or registers on E-UTRAN, and establishes connection. On the network side, this will appear as a failure case or existing error condition to the IJTRAN. These situations are handled accordingly by the network.

However, if a suitable E-IJ[RAN cell is not available, then the User Equipment completes the reconfiguration as normal by sending a Radio Bearer Reconfiguration Complete message in block 69, with a slight delayed completion time.

FIG. 4 is a simplified call flow diagram of the method 50 shown [n FIG. 3.

The User Equipment is camped on a cell in UTRAN and is in a connected or CELL DCH state. In response to receiving a Radio Bearer Reconfiguration message from the network, the User Equipment begins reconfiguration from the CELL_DCH state to the CELL FACH state. The User Equipment also disconnects from the network to perform the reconfiguration, and camps on a cell, and monitors broadcast system information messages on a communication channel of the serving cell, such as the Secondary Common Control Physical Channel (S-CCPCH) that carries a EACH.

The User Equipment then performs cell measurement to select available E-UTRAN resources. The broadcast system information message from the serving cell may include a neighbour cell list that identifies neighbouring cells from which the User Equipment may monitor and select. The list may provide neighbouring E-UTRAN frequencies. The User Equipment makes a determination as to whether a suitable E-UTRAN ccli is available. A number of predetermined criteria arc used to determine whether an E-UTRAN cell is suitable and is not the focus of this disclosure.

The cell measurement evaluation at WCDMA Layer I (WLI) and E-U'T RAN Layer 1 (ELI) makes a determination whether suitable E-UTRAN is found. This may be a "fast" measurement and evaluation that involves a quick scan of known LT[ frequencies. If a suitable E-UTRAN ccli is available, then the User Equipment performs a cell reselection procedure and selects or registers on E-UTRAN, and establishes connection. On the network side, this will appear as a failure case or existing error condition to the UTRAN. These situations are handled accordingly by the network. However, if a suitable E-UTRAN cell is not available, then the User Equipment completes the reconfiguration as normal by sending a Radio Bearer Reconfiguration Complete message, with a slight delayed completion time.

FIG. 5 is a simplified flowchart of another exemplary cmbodiment of a method 70 of E-UTRAN cell measurement and selection during RRC state transition.

In block 72, the User Equipment has camped on the cell in UTRAN and is in a CELL_DCI-1 state, for example. In block 74, the User Equipment begins reconfiguration from the CELL_DCH state to the CELL_FACH state in response to a Radio Bearer Reconfiguration message from the network. Upon receiving the reconfiguration message, the User Equipment disconnects from the network to perform the reconfiguration, as shown in block 76. The User Equipment then performs cell selection in block 78. In block 80, the User Equipment camps on a cell and monitors the FACH carried on the S-CCPCH, for example. In block 82, a determination is made as to whether cell reseleetion to E-UTRAN should be performed. For example, cell reselection may be limited to when the User Equipment has been suitably campcd on LTE to ensure that suitable LTE coverage is present.

This cell reselection process may be limited to only circumstances when FACH Measurement Occasions or DRX are not available. Another limitation may be when CELL FACH measurement to LTE is not enabled. This knowledge may be obtained from the System Information Blocks received from the serving cell. Another way to limit the performance of this cell reselection procedure is to permit it only when certain NT fingerprint matches a known LTE coverage area, when certain data patterns are detected such as bursty data transmission'reception, etc. These are examples of criteria that may be employed separately or together to limit or control the cell measurement and reselection method disclosed herein.

If E-UTRAN measurement criteria are not met as determined in block 82, then in block 84 the User Equipment sends a Radio Bearer Reconfiguration Complete message to the network to indicate transition to the CELL_EACH state is completed and the User Equipment returns to the CELL_FACE state in block 86.

If on the other hand the E-UTRAN measurement criteria are met, then in block 88 cell measurement and evaluation of available E-UTRAN cell or frequencies is performed. This may be a "fast" measurement and evaluation that involves a quick scan of known LTE frequencies. This first measurement and evaluation step provides an indication of whether an E-UTRAN cell is available. In block 90, the User Equipment then sends a Radio Bearer Reconfiguration Complete message to the network to indicate transition to the CELL EACH state is completed. In block 92, based on the first cell measurement and evaluation step, a second cell measurement is forced and evaluation step is made in the CELL FACH state to confirm whether reselection criteria are met by a suitable E-UTRAN cell. In block 94, a determination is made as to whether a suitable E-UTRAJ" cell is available. If a suitable E-UTRAN cell is available, then the User Equipment performs a cell reselection procedure and selects or registers on E-UTRAN, and establishes connection in block 96. If reselection fails, the User Equipment returns to the CELL_EACH state in block 86.

The network in this instance would not be aware of the failed cell reselection.

FIG. 6 is a simplified call flow diagram of the method 70 shown in FIG. 5.

The User Equipment is camped on a cell in UTRAN and is in a connected or CELL_DCH state. In responsc to receiving a Radio Bearer Reconfiguration message from the network, the User Equipment begins reconfiguration from the CELL DCH state to the CELL FACT-I state. The User Equipment also disconnects from the network to perform the reconfiguration, and camps on a cell and monitors broadcast system information messages on a communication channel of the serving cell, such as the Secondary Common Control Physical Channel (S-CCPCH) that canies a FACH.

The User Equipment then performs cell measurement to select available E-UTRAN resources. The broadcast system information message from the serving cell may include a neighbour cell list that identifies neighbouring cells from which the User Equipment may monitor and select. The list may provide neighbouring E-UTRAN frequencies. The User Equipment makes a determination as to whether a suitable E-UTRAN cell is available. However, this first measurement and evaluation step does not trigger a reselection but provides information as to available suitable LTE coverage. A number of predetermined criteria are used to determine whether an E-UTRAN cell is suitable and is not the focus of this disclosure. The cell measurement evaluation at WCDMA Layer 1 (WLI) and E-UTRAN Layer I (ELI) makes a determination whether a suitable E-UTRAN is found. This may be a "fast" measurement and evaluation that involves a quick scan of known LTE frequencies.

The User Equipment then transmits a Radio Bearer Reconfiguration Complete to CELL EACH message to the network. The User Equipment then takes a second cell measurement and evaluation step based on the results from the first measurement and evaluation step. Due to a high confidence of success, the User Equipment "steals" time from the CELL FACH to perform the second measurement and evaluation step.

If a suitable E-UTRAN cell is available, then the User Equipment performs a cell S (re)selection procedure in CELL FACH and establishes connection. However, if a suitable E-UTRAN cell is not available, then the User Equipment returns to the CELL FACH state and the network would not be aware of the failed cell reselection.

FIG. 7 is a simplified block diagram of an exemplary WTRU or User Equipment 100 configured or arranged to perform cell measurement and rcselection to E-IJTRAN as described above. The WTRU 100 includes a processor 102, a transceiver 104, a transmit/rcccive element 106, and may further includc a speaker/microphone 108, a keypad 110, a displayttouchpad 112, non-removable memory 114, removable memory 116, a power source 118, a global positioning system (GPS) chipset 120, and other peripherals 122.

The processor 102 may be a general purpose processor, a special purpose processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Array (FPGA5) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 102 may perform signal coding, data processing, power control, input/output processing, and/or any other functionality that enables the WTRIJ 100 to opcratc in a wireless environment. The processor 102 may be coupled to the transceiver 104, which may be coupled to the transmit/receive element 106. While FIG. 7 depicts the processor 102 and the transceiver 104 as separate components, it should be appreciated that the processor 102 and the transceiver 104 may be integrated together in an electronic package or chip.

The transmit/receive clement 1 06 is configured to transmit signals to and/or receive signals from a base station over the air interface. For example, in one embodiment, the transmit/receive element 106 may be an antenna configured to transmit and/or receive RF (radio frequency) signals. In another embodiment, the transmit/receive element 106 may be an emitter/detector configured to transmit and/or receive JR (infrared), IJV (ultra-violet), visible light signals, and/or a combination thereof It will be appreciated that the transmit/receive element 106 may be configured to transmit and/or receive any combination of wireless signals. In addition, although the transmit/receive element 106 is depicted in FIG. 7 as a single clement, the WTRU 100 may include any number of transmit/receive elements 106.

More specifically, the WTRU 100 may employ MIMO (multiple input muhiple output) technology. Thus, in one embodiment, the WTRU 100 may include two or more transmit/receive elements 106 (e.g. multiple antennas) for transmitting and receiving wireless signals over the air interface. The transceiver 104 may be configured to modulate the signals that are to be transmitted by the transmit/receive clement 106 and to demodulate the signals that are received by the transmit/receive element 106. As noted above, the WTRLT 100 may have multi-mode capabilities.

Thus, the transceiver 104 may include multiple transceivers for enabling the WTRU to communicate via multiple RATs (Radio Access Technologies), such as UTRA and IEEE 802.11 (commonly called WiFi), for example.

The processor 102 of the WTRU 100 may be coupled to, and may receive user input data from, the speaker/microphone 108, the keypad 110, and/or the display/touchpad 112 (e.g. a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit). The processor 102 may also output user data to the speaker/microphone 108, the keypad 110, and/or the display/touchpad 112. In addition, the processor 102 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 114 and/or the removable memory 106. The non-removable memory 114 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 116 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 102 may access information from, and store data in, memory that is not physically located on the WTRU 100, such as on a server or a home computer (not shown). The non-removable memory 114 and/or the removable memory 116 are configured to store myriad types of data, including computer program instructions, control data, status data, and user data (e.g. text, images, video, audio, music, emails, records, documents, and files).

The processor 102 may receive power from the power source 118, and may be configured to distribute and/or control the power to the other components in the WTRU 100. The power source 118 may be any suitable device for powering the WTRIJ 100. For example, the power source 118 may include one or more dry cell batteries (e.g. nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like. The processor 102 may also be coupled to the GPS chipsct 120, which may be configured to provide location information (e.g. longitude, latitude, and altitude) regarding the current location of the WTRU 100. In addition to, or in lieu of; the information from the GPS chipset 120, the WTRIJ 100 may receive location information over the air interface from a base station and/or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRIJ 100 may acquire location information by way of any suitable location-determination method. The processor 102 may further be coupled to other peripherals 122, which may include one or more software, firmware, and/or hardware modules that provide additional features, functionality and/or wired or wireless connectivity.

For example, the peripherals 122 may include an accelerometer, an c-compass, a satellite transceiver, a digital camera (for photographs and/or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluctooth (RTM) module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, and the like.

When referred to herein, the terminology "wireless transmit/receive unit (WTRU)" includes but is not limited to a User Equipment, a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant

S

(PDA), a computer, a laptop, a portable device, or any other type of user device capable of transmitting and/or receiving wireless signals and operating in a wireless environment. When referred to herein, the terminology "base station" includes but is not Hmited to a Node-B, an evolved Node-B (eNodeB), a site controller, an access point (AP), or any other type of interfacing device capable of operating in a wireless environment.

The above embodiments are to be understood as illustrative examples of the invention. Further embodiments of the invention are envisaged. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be cmpoyed without departing from the scope of the invention, which is defined in the accompanying claims.

Claims

<claim-text>CLAIMS1. A method for use in a user equipment, the method comprising performing cell measurement and evaluation on another frequency or system during a transition from S a first state to a second state, where a cell measurement is not normally possible in the first and second states.</claim-text> <claim-text>2. A method according to claim 1, wherein performing cell measurement and evaluation comprises performing cell measurement and evaluation during a transition to a CELL FACH state to identify a suitable E-TJTRAN cell.</claim-text> <claim-text>3. A method according to claim 1 or claim 2, comprising: in response to at least a reasonable level of confidence of coverage determined by cell measurements and evaluation performed during state transition, forcing further cell measurement and evaluation in the second state to confirm the decision to reselect to a cell on another frequency or system.</claim-text> <claim-text>4. A method according to claim 1 or 2, comprising: in response to at least a reasonable level of confidence of coverage detemiined by cell measurements and evaluation performed during state transition, forcing reseleetion to a eel! on another frequency or system before completing the state transition to the second state.</claim-text> <claim-text>5. A method according to claim or 2, comprising: in response to at least a reasonable level of confidence of coverage determined by cell measurements and evaluation performed during state transition, forcing reselection to a cell on another frequency or system after completing the state transition to the second state.</claim-text> <claim-text>6. A method according to any of claims to 5, wherein performing cell measurement and evaluation comprises performing a fast measurement and evaluation of a number of known candidate frequencies.</claim-text> <claim-text>7. A method according to any of claims 1 to 6, comprising satisIing at least one measurement condition prior to performing ecU measurement and evaluation.</claim-text> <claim-text>8. A method according to claim 7, wherein satisfying at least one measurement condition comprises determining that there is suitable coverage on another frequency or system.</claim-text> <claim-text>9. A method according to claim 7 or claim S, wherein satisfying at least one measurement condition comprises determining that measurement opportunities are not available in the second state.</claim-text> <claim-text>10. A method according to claim 9, wherein satisfying at least one measurement condition comprises determining that measurement occasions are not available in the CELL FACH state.</claim-text> <claim-text>11. A method according to claim 9 or claim 10, wherein satisfying at least one measurement condition comprises determining that discontinuous reception is not available in the CELL FACH state.</claim-text> <claim-text>12. A method according to any of claims 7 to 11, wherein satisfying at least one measurement condition comprises determining that CELL FACH measurements to LTE is not enabled.</claim-text> <claim-text>13. A method according to any of claims 7 to 12, wherein satisfying at least one measurement condition comprises detecting a certain data transmission/reception pattern.</claim-text> <claim-text>14. Apparatus comprising a processing system for a wireless communication device constructed and arranged to perform cell measurement and evaluation on another frequency or system during a transition from a first state to a second state, where a ccli measurement is not normally possible in the first and second states.</claim-text> <claim-text>15. Apparatus according to claim 14, arranged such that performing cell measurement and evaluation comprises performing cell measurement and evaluation during a transition to a CELL_FACH state to identify a suitable E-UTRAN cell.</claim-text> <claim-text>16. Apparatus according to claim 14 or claim 15, arranged to force further cell measurement and evaluation in the second state to confirm the decision to reselect to a ccli on another frequency or system in rcsponse to at least a reasonable level of confidence of covcragc determined by cell mcasurements and evaluation performed during state transition.</claim-text> <claim-text>17. Apparatus according to claim 14 or claim 15, arranged to force reselcction to a cell on another frequency or system before completing the state transition to the second state in response to at least a reasonable level of confidence of coverage determined by cell measurements and evaluation performed during state transition.</claim-text> <claim-text>18. Apparatus according to claim 14 or claim 15, arranged to force reselection to a cell on another frequency or system after completing the state transition to the second state in response to at least a reasonable level of confidence of coverage determined by cell measurements and evaluation performed during state transition.</claim-text> <claim-text>19. Apparatus according to any of claims 14 to 18, wherein performing cell measurement and evaluation comprises performing a fast measurement and evaluation of a number of known candidate frequencies.</claim-text> <claim-text>20. Apparatus according to any of claims 14 to 19, arranged to satisfy at least one measurement condition prior to performing cell measurement and evaluation.</claim-text> <claim-text>21. Apparatus according to claim 20, wherein means for satisfying the at least one measurement condition comprises means for determining that there is suitable coverage on another frequency or system.</claim-text> <claim-text>22. Apparatus according to claim 20 or claim 21, wherein satisfying at least one measurement condition comprises determining that measurement opportunities are not available in the second state.</claim-text> <claim-text>23. Apparatus according to claim 22, wherein satisfying at least one measurement condition comprises determining that measurement occasions are not available in the CELL FACH state.</claim-text> <claim-text>24. Apparatus according to claim 22 or claim 23, wherein satisfying at least one measurement condition comprises determining that discontinuous reception is not available in thc CELL FACH statc.</claim-text> <claim-text>25. Apparatus according to any of claims 20 to 24, wherein satis1'ing at least one measurement condition comprises determining that CELL FACH measurements to LTE is not enabled.</claim-text> <claim-text>26. Apparatus according to any of claims 20 to 25, wherein satisfying at least one measurement condition comprises detecting a certain data transmissionrecept ion pattern.</claim-text> <claim-text>27. A computer program comprising instructions that cause a wireless communications device to perform the steps of: performing cell measurement and evaluation on another frequency or system during a transition from a first statc to a second state, where a cell measurement is not normally possible in the first and second states.</claim-text> <claim-text>28. A computer program according to claim 27, wherein the performing cell measurement and evaluation comprises performing cell measurement and evaluation during a transition to a CELL_FACE! state to identify a suitable E-IJTRAN cell.</claim-text> <claim-text>29. A computer program according to claim 27 or claim 28, wherein the wireless communications device is caused to perform the step of in response to at least a reasonable level of confidence of coverage determined by cell measurements and evaluation performed during state transition, forcing further cell measurement and evaluation in the second state to confirm the decision to reselect to a cell on another frequency or system.</claim-text> <claim-text>30. A computer program according to claim 27 or claim 28, wherein the wireless communications device is caused to perform the step of: in response to at least a reasonable level of confidence of coverage determined by cell measurements and evaluation performed during state transition, forcing reseleetion to a cell on another frequency or system before completing the state transition to the second state.</claim-text> <claim-text>31. A computer program according to claim 27 or claim 28, wherein the wireless communications device is caused to perform the step of in response to at least a reasonable level of confidence of coverage determined by cell measurements and evaluation performed during state transition, forcing reselection to a cell on another frequency or system after completing the state transition to the second state.</claim-text> <claim-text>32. A computer program according to any of claims 27 to 31, wherein the wireless communications device is caused to perform the step of performing a fast measurement and evaluation of a number of known candidate frequencies.</claim-text> <claim-text>33. A computer program according to any of claims 27 to 32, wherein the wireless communications device is caused to perform the step of satisfying at least one measurement condition prior to performing cell measurement and evaluation.</claim-text> <claim-text>34. A computer program according to claim 33, wherein the wireless communications device is caused to perform the step of determining that there is suitable coverage on another frequency or system.</claim-text> <claim-text>35. A computer program according to claim 33 or claim 34, wherein the wireless communications device is caused to perform the step of determining that measurement opportunities are not available in the second state.</claim-text> <claim-text>36. A computer program according to claim 35, wherein the wireless communications device is caused to perform the step of determining that measurement occasions are not available in the CELL EACI-1 state.</claim-text> <claim-text>37. A computer program according to claim 35 or claim 36, wherein the wireless communications device is caused to perform the step of determining that discontinuous reception is not available in the CELL_EACH state.</claim-text> <claim-text>38. A computer program according to any of claims 33 to 37. wherein the wireless communications device is caused to perform the step of determining that CELL FACI-! measurements to LTE is not enabled.</claim-text> <claim-text>39. A computer program according to any of claims 33 to 38, wherein the wireless communications device is caused to perform the step of detecting a certain data transmission/reception pattern.</claim-text> <claim-text>40. A wireless dcvice comprising apparatus according to any of claims 14 to 26.</claim-text> <claim-text>41. A method of operating a wireless device, substantially in accordance with any of the examples as described herein with reference to and illustrated by the accompanying drawings.</claim-text> <claim-text>42. Apparatus comprising a processing system for a wirdess device, substantiafly in accordance with any of the examples as described herein with reference to and illustrated by the accompanying drawings.AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWSCLAIMS1. A method for use in a user equipment, the method comprising performing cell measurement and evaluation on another frequency or system during a transition from a first Radio Resource Control state to a second Radio Resource Control state, where a cell measurement is not normally possible in the first and second Radio Resouree Control states.
2. A method according to claim 1, wherein performing cell measurement and evaluation comprises performing cell measurement and evaluation during a transition to a CELL_EACH state to identify a suitable E-UTRAN cell.
3. A method according to claim 1 or claim 2, comprising: in response to at least a reasonable level of confidence ot coverage determined by cell measurements and evaluation performed during state transition, forcing further cell measurement and evaluation in the second Radio Resource Control state to confirm a decision to reselect to a cell on another frequency or system.
4. A method according to claim I or 2, comprising: in response to at least a reasonable level of confidence of coverage determined by cell measurements and evaluation perfornied during state transition, forcing reselection to a cell on another frequency or system before completing the state transition to the second Radio Resource Control state.
5. A method according to claim 1 or 2, comprising: in response to at least a reasonable level of confidence of coverage determined by cell measurements and evaluation performed during state transition, forcing reseleetion to a cell on another frequency or system after completing the state transition to the second Radio Resource Control state.
6. A method according to any of claims 1 to 5, wherein performing cell measurement and evaluation comprises performing a fast measurement and evaluation of a number of known candidate frequencies.
7. A method according to any of claims ito 6, comprising satisfying at least one measurement condition prior to performing cell measurement and evaluation.
8. A method according to claim 7, wherein satisfying at least one measurement condition comprises determining that there is suitable coverage on another frequency or system.
9. A method according to claim 7 or claim 8, wherein satisfying at least one measurement condition comprises determining that measurement opportunities are not available in the second Radio Resoume Control state.
10. A method according to claim 9, wherein satisfying at least one measurement condition comprises determining that measurement occasions are not available in the CELL FACH state.
11. A method according to claim 9 or claim 10, wherein satisfying at least one measurement condition comprises determining that discontinuous reception is not available in the CELL FACJ-1 state.
12. A method according to any of claims 7 to 11, wherein satisfying at least one measurement condition comprises deteimining that CELL_EACH measurements to LU is not enabled.
13. A method according to any of claims ito 12, wherein satisfying at least one measurement condition comprises detecting a certain data transmission/reception pattern.
14. Apparatu.s comprising a processing system for a wireless communication device constructed and arranged to perform cell measurement and evaluation on another frequency or system during a transition from a first Radio Resource Control state to a second Radio Resource Control state, where a cell measurement is not normally possible in the first and second Radio Resource Control states.
1 5. Apparatus according to claim 14, arranged such that performing cell measurement and evaluation comprises performing cell measurement and evaluation during a transition to a CElL EACH state to identi' a suitable F-LJTRAN cell.
16. Apparatus according to claim 14 or claim 15, arranged to force further cell measurement and evaluation in the second Radio Resource Control state to confirm a decision to reselect to a cell on another frequency or system in response to at least a reasonable level of confidence of coverage determined by cell measurements and evaluation performed during state transition.1?. Apparatus according to claim 14 or claim 15, arranged to force rcselection to a cell on another frequency or system before completing the state transition to the second Radio Resource Control state in response to at least a reasonablc level of confidence of coverage determined by cell measurements and evaluation performed during state transition.18. Apparatus according to claim 1401-claim iS, arranged to force reselection to a cell on another frequency or system after completing the state transition to the second Radio Resource Control state in response to at least a reasonable level of confidence of coverage determined by cell measurements and evaluation performed during state transition.19. Apparatus according to any of claims 14 to 18, wherein performing cell measurement and evaluation comprises performing a fast measurement aM evaluation of a number of known candidate frequencies.20. Apparatu.s according to any of claims 14 to 19, arranged to satisfy at least one measurement condition prior to performing cell measurement and evaluation.21. Apparatus according to claim 20, whercin means for satisfying the at least one measurement condition comprises means for determining that there is suitable coverage on another frequency or system.22. Apparatus according to claim 20 or claim 21, wherein satis4ng at least one measurement condition comprises determining that measurement opportunities are not available in the second Radio Resoume Control state, 23. Apparatus according to claim 22, wherein sa.tisf'ing at lcast one measurement condition compnses detenmnnig that measurement occasions are not available ui the CELL EACH state.24. Apparatus according to claim 22 or claim 23, wherein satisring at least one measurement condition comprises determining that discontinuous reception is not available in the CELL_EACH state.25. Apparatus according to any of claims 20 to 24, wherein satis'ing at least one measurement condition comprises dctermining that CELL_EACH measurements to LU is not enabled.26. Apparatus according to any of claims 20 to 25. wherein satis1ing at least one measurement condition comprises detecting a certain data transmissionireception pattern.27. A computer program comprising instructions that cause a wireless communications device to perform the steps of: performing cell measurement and evaluation on another frequency or system during a transition from a first Radio Resource Control state to a second Radio Resource Control state, where a cell measurement is not normally possible in the first and second Radio Resource Conol states.28. A computer program according to claim 27, wherein the performing cell measurement and evaluation comprises performing cell measurement and evaluation during a transition to a CELL FACH state to identify a suitable E-UTRAN cell.29. A computer program according to claim 27 or claim 28, wherein the wirclcss communications device is caused to perform the step of: in response to at least a reasonable level of confidence of coverage determined by cell measurements and evaluation performed during state transition, forcing frirther cell measurement and evaluation in the second Radio Resource Control state to confirm a decision to reselect to a cell on another frequency or system.30. A computer program according to claim 27 or claim 28, wherein the wireless communications device is caused to perform the step of: in responsc to at least a reasonable level of confidence of coverage determined by cell measurements and evaluation performed duing state transition, forcing resetection to a cell on another frequency or system before completing the state transition to the second Radio Resource Control state.31. A computer program according to claim 27 or claim 28, wherein the wireless communications device is caused to perform the step of: in response to at least a reasonable level of confidence of coverage determined by eel! measurements and evaluation perfoniied during state transition, forcing reselection to a cell on another frequency or system after completing the state transition to the second Radio Resource Control state.32. A computer program according to any of claims 27 to 3!, whercin the wireless communications device is caused to perform the step of performing a itt measurement and evaluation of a number of known candidate frequencies.33. A computer program according to any of claims 27 to 32, wherein the wireless communications device is caused to perform the step of satis'ing at least one measurement condition prior to performing cell measurement and evaluation.34. A computer program according to claim 33, wherein the wireless communication device is caused to perform the step of determining that there is suitable coverage on another frequency or system.35. A computer program according to claim 33 or claim 34, wherein the wireless communications device is caused to perform the step of determining that (0 15 measurement opportunities are not available in the second Radio Resoume Control state.36. A computer program according to claim 35, wherein the wireless communications device is caused to perform the step of determining that measurement oecasions are not available in the CELL_FAd state.37. A computer program according to claim 35 or claim 36, wherein the wireless communications device is caused to pertbrm the step of determining that discontinuous reception is not available in the CELL ACH state.38. A computer program according to any of claims 33 to 37, wherein the wireless communications device is caused to perform the step of determining that CELL_FACH measurements to LTE is not enabled.39. A computer program according to any of claims 33 to 3S, wherein the wireless communications device is caused to perform the step of dctccting a certain data transmission/reception pattern.40. A wireless device comprising apparatus according to any of cLaims 14 to 26.41. A method of operating a wireless device, substantially in accordance with any of the examples as described herein with reference to and illustrated by the accompanying drawings.42. Apparatus comprising a processing system for a wireless device, substantially in accordance with any of the examples as described herein with reference to and illustrated by the accompanying drawings.CD -a</claim-text>