WO2014098386A1

WO2014098386A1 - Method and apparatus for determining cell selection quality value in wireless communication system

Info

Publication number: WO2014098386A1
Application number: PCT/KR2013/010848
Authority: WO
Inventors: 정명철; 권기범; 안재현
Original assignee: 주식회사 팬택
Priority date: 2012-12-20
Filing date: 2013-11-27
Publication date: 2014-06-26
Also published as: KR20140080279A

Abstract

Provided are a method and an apparatus for determining a cell selection quality value (Squal) in a wireless communication system of which a system bandwidth is higher than or equal to 10 MHz or a maximum allowed bandwidth for measurement more than or equal to 50 resource blocks. User equipment receives from a base station a bandwidth gap offset and a wideband reference signal received quality (RSRQ) measurement indicator which indicates whether the user equipment can measure the wideband RSRQ, measures the RSRQ based on the wideband RSRQ measurement indicator, and determines the cell selection quality value based on the measured RSRQ.

Description

Method and apparatus for determining cell selection quality value in wireless communication system

The present invention relates to wireless communication, and more particularly, to a method and apparatus for determining a cell selection quality value in a wireless communication system.

In a 3rd generation partnership project (3GPP) long term evolution advanced (LTE-A), a user equipment (UE) and an evolved universal terrestrial radio access network (E-UTRAN) are in an idle mode and a connected mode. Various kinds of measurements may be performed to support the operation in the mode. The higher layer initializes and controls the measurement of the first layer L1, that is, the physical layer. The physical layer provides measurement capability of the terminal and the network. Measurements can be made with different measurements, such as intra-frequency, inter-frequency, inter-system, traffic volume, quality, and internal measurements. It can be divided into types. In addition, the measurement may be divided into a measurement performed by the terminal and a measurement performed by the network.

The network transmits a radio resource control (RRC) connection reconfiguration message to the terminal to initialize a specific measurement. The RRC connection reconfiguration message may include a measurement identifier (ID), a measurement type, a command (set, change, release, etc.), a measurement object, a measurement amount, a report amount, a report criterion (periodic / event trigger), and the like. If the reporting criteria is met, the terminal transmits a measurement report message to the network. The measurement report message may include a measurement ID and a measurement result. In idle mode, measurement information elements (IE) may be broadcast via system information.

There are reference signal received power (RSRP) and reference signal received quality (RSRQ) among the measurement capabilities of the UE. RSRP is defined as a linear average of the power contributions of resource elements (RE) carrying a cell-specific reference signal (CRS) within a measurement frequency bandwidth. In order to measure RSRP, CRS transmitted through antenna port 0 is used. In addition, when the UE can reliably detect the CRS transmitted through the antenna port 1, the CRS transmitted through the antenna port 1 may also be used to measure the RSRP. The reference point of the RSRP is an antenna connector of the terminal. When the terminal uses receiver diversity, the value reported to the network may not be smaller than the RSRP corresponding to any individual diversity.

RSRQ is defined as N * RSRP / (E-UTRA carrier RSSI (received signal strength indicator). N is the number of resource blocks (RBs) of the E-UTRA carrier RSSI measurement bandwidth. The measurements in the numerator and denominator are then carried out over the same set of RBs. The E-UTRA carrier RSSI includes a linear average of the total received power observed only in orthogonal frequency division multiplexing (OFDM) symbols containing reference symbols for antenna port 0 over N RBs within the measurement bandwidth. In this case, the total received power is a signal transmitted from all sources, that is, a signal transmitted from a serving cell and a neighboring cell of a co-channel and an adjacent channel interference. ) And power reception for thermal noise and the like. If a specific subframe for performing RSRQ measurement is indicated by a higher layer, the RSSI may be measured across all OFDM symbols within the indicated subframe. The reference point of the RSRQ is the antenna connection of the terminal. When the terminal uses receiver diversity, the value reported to the network may not be smaller than the RSRP corresponding to any individual diversity. In addition, the measurement of RSRQ may be performed on cells within frequency or between cells in idle mode.

In general, it is required to measure the RSRQ for at least six RBs in the center of a measurement frequency carrier. Since the CRS is present over the entire system bandwidth, the RSRQ may be measured for the entire system bandwidth. However, in consideration of power consumption or efficiency of the UE, it is preferable to measure the RSRQ for 6 RBs. This may be referred to as a narrowband RSRQ measurement method. The base station may inform the terminal of the maximum allowed bandwidth for measurement through the AllowedMeasBandwidth field transmitted through the upper layer.

The narrowband RSRQ measurement method is not a problem when the serving cells and neighbor cells of the same channel are configured with the same bandwidth. However, when the bandwidths of the serving cell and the neighboring cell are different from each other, there may be a gap in which the bandwidths of the serving cell and the neighboring cell do not overlap each other. Especially, when the bandwidth of the serving cell is 10 MHz or more, the gap size is 6 It may be RB or higher. When the RSRQ is measured in this gap, less interference from neighboring cells is reflected, and thus a better RSRQ can be measured. In other words, an incorrect RSRQ may be measured differently from the actual RSRQ. In the idle mode, the UE performs cell selection or cell reselection by comparing a cell selection quality value calculated based on the measured RSRQ with a reference quality value received from the base station. Due to the RSRQ, a problem may occur when performing cell selection or cell reselection.

Therefore, a method for accurately measuring RSRQ in idle mode may be required.

An object of the present invention is to provide a method and apparatus for determining a cell selection quality value in a wireless communication system. The present invention provides a method for a UE to determine a cell selection quality value by measuring a reference signal received quality (RSRQ) in an idle mode. The present invention provides a method for determining cell selection quality values by measuring wideband RSRQ. Alternatively, the present invention provides a method of measuring a narrowband RSRQ and determining a cell selection quality value based on an offset. The present invention proposes a method for performing cell selection or cell reselection based on the determined cell selection quality value.

In one aspect, a cell selection quality value by a terminal in a wireless communication system having a system bandwidth of 10 MHz or more or a maximum allowable bandwidth for measurement of 50 resource blocks (RB) or more A method for determining Squal is provided. The method receives a wideband RSRQ measurement indicator and a bandwidth gap offset indicating whether the terminal can measure a wideband reference signal received quality (RSRQ) from a base station, and receives an RSRQ based on the wideband RSRQ measurement indicator. Measuring, and determining the cell selection quality value based on the measured RSRQ.

In another aspect, a terminal is provided in a wireless communication system having a system bandwidth of 10 MHz or more or a maximum allowable bandwidth for measurement of 50 resource blocks (RB) or more. The terminal includes a radio frequency (RF) unit for transmitting or receiving a radio signal, and a processor connected to the RF unit, wherein the processor measures a wideband reference signal received quality (RSRQ) by the terminal from a base station. Receive a broadband RSRQ measurement indicator and a bandwidth gap offset indicating whether or not it is possible, measure an RSRQ based on the wideband RSRQ measurement indicator, and determine a cell selection quality value based on the measured RSRQ; Configured to determine.

The cell selection quality value can be determined more accurately.

1 shows a wireless communication system to which the present invention is applied.

2 is an exemplary diagram illustrating a cell selection process of a UE in an RRC idle state according to an embodiment of the present invention.

3 shows that the cell selection range changes according to Q _qualmin .

4 illustrates a case where bandwidths of a serving cell and a neighbor cell of the same channel are different from each other.

5 illustrates an embodiment of a system information transmission method according to an embodiment of the present invention.

6 illustrates an example of a method for determining a cell selection quality value according to an embodiment of the present invention.

7 is a block diagram of a wireless communication system in which an embodiment of the present invention is implemented.

Hereinafter, the present disclosure will be described in detail with reference to the accompanying drawings and examples, together with the contents of the present disclosure. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even though they are shown in different drawings. In addition, in describing the embodiments of the present specification, when it is determined that the detailed description of the related well-known configuration or function may obscure the subject matter of the present specification, the detailed description thereof will be omitted.

In addition, the present specification describes a wireless communication network, the operation performed in the wireless communication network is performed in the process of controlling the network and transmitting data in the system (for example, the base station) that is in charge of the wireless communication network, or the corresponding wireless Work may be done at the terminal coupled to the network.

1 shows a wireless communication system to which the present invention is applied. This may also be called an evolved-UMTS terrestrial radio access network (E-UTRAN), or a long term evolution (LTE) / LTE-A (advanced) system.

Referring to FIG. 1, an E-UTRAN includes a base station (BS) 20 that provides a control plane and a user plane to a user equipment (UE). The terminal 10 may be fixed or mobile and may be called by other terms such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), a mobile terminal (MT), and a wireless device. . The base station 20 refers to a station communicating with the terminal 10, and may be referred to in other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), and an access point.

The base stations 20 may be connected to each other through an X2 interface. The base station 20 is connected to the serving gateway (S-GW) through the mobility management entity (MME) and the S1-U through the evolved packet core (EPC) 30, more specifically, through the S1 interface. The S1 interface exchanges signals with the MME to exchange OAM (operation and management) information for supporting the movement of the terminal 10.

The EPC 30 is composed of MME, S-GW and P-GW (packet data network gateway). The MME has access information of the terminal 10 or information on the capability of the terminal 10, and this information is mainly used for mobility management of the terminal 10. S-GW is a gateway having an E-UTRAN as an endpoint, and P-GW is a gateway having a PDN as an endpoint.

The layers of the radio interface protocol between the terminal 10 and the network are based on the lower three layers of the open system interconnection (OSI) reference model, which is well known in a communication system. Layer), L2 (second layer), and L3 (third layer). Among them, a physical layer (PHY) belonging to the first layer may include an information transmission service using a physical channel ( An information transfer service (RRC) layer and a radio resource control (RRC) layer located in a third layer play a role of controlling radio resources between the terminal 10 and the network. To this end, the RRC layer exchanges an RRC message between the terminal 10 and the base station.

The physical layer provides an information transmission service to a higher layer using a physical channel. The physical layer is connected to a medium access control (MAC) layer belonging to a second layer through a transport channel. Data travels between the MAC and physical layers over the transport channel. Transport channels are classified according to how and with what characteristics data is transmitted over the air interface.

Data travels through physical channels between different physical layers, that is, between physical layers of a transmitter and a receiver. The physical channel is modulated by an orthogonal frequency division multiplexing (OFDM) scheme and utilizes time and frequency as radio resources.

Functions of the MAC layer include mapping between logical channels and transport channels and multiplexing / demultiplexing into transport blocks provided as physical channels on transport channels of MAC service data units (SDUs) belonging to the logical channels. The MAC layer provides a service to a radio link control (RLC) layer through a logical channel.

Functions of the RLC layer belonging to the second layer include concatenation, segmentation, and reassembly of RLC SDUs. In order to guarantee various quality of service (QoS) required by a radio bearer (RB), the RLC layer may be configured in transparent mode (TM), unacknowledged mode (UM) and acknowledgment mode (AM). Three modes of operation are provided: acknowledged mode. AM RLC provides error correction through an automatic repeat request (ARQ).

Functions of the packet data convergence protocol (PDCP) layer in the user plane include delivery of user data, header compression and ciphering. Functions of the PDCP layer in the user plane include the transfer of control plane data and encryption / integrity protection.

The RRC layer belonging to the third layer is defined only in the control plane. The RRC layer is responsible for the control of logical channels, transport channels and physical channels in connection with the configuration, re-configuration and release of radio bearers. RB means a logical path provided by the first layer (PHY layer) and the second layer (MAC layer, RLC layer, PDCP layer) for data transmission between the terminal 10 and the network. The establishment of the RB means a process of defining characteristics of a radio protocol layer and a channel to provide a specific service, and setting each specific parameter and operation method. The RB can be further divided into a signaling RB (SRB) and a data RB (DRB). The SRB is used as a path for transmitting RRC messages in the control plane, and the DRB is used as a path for transmitting user data in the user plane.

If there is an RRC connection between the RRC layer of the terminal 10 and the RRC layer of the E-UTRAN, the terminal 10 is in an RRC CONNECTED state, otherwise the RRC idle ) State.

The downlink transmission channel for transmitting data from the network to the terminal 10 includes a broadcast channel (BCH) for transmitting system information and a downlink shared channel (SCH) for transmitting user traffic or control messages. Traffic or control messages of the downlink multicast or broadcast service may be transmitted through the downlink SCH or may be transmitted through a separate downlink multicast channel (MCH). Meanwhile, the uplink transmission channel for transmitting data from the terminal 10 to the network includes a random access channel (RACH) for transmitting an initial control message and an uplink shared channel (SCH) for transmitting user traffic or control messages. have.

Above logical channels, logical channels mapped to the transport channels include a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH), a multicast control channel (MCCH), and multicast traffic (MTCH). channel).

The physical channel is composed of several symbols in the time domain and several subcarriers in the frequency domain. One subframe consists of a plurality of symbols in the time domain. One subframe includes a plurality of resource blocks (RBs), and one resource block includes a plurality of symbols and a plurality of subcarriers. In addition, each subframe may use specific subcarriers of specific symbols (eg, the first symbol) of the corresponding subframe for a physical downlink control channel (PDCCH), that is, an L1 / L2 control channel. A transmission time interval (TTI), which is a unit time for transmitting data, is 1 ms corresponding to one subframe.

Hereinafter, the RRC state and the RRC connection method of the UE will be described in detail.

The RRC state refers to whether or not the RRC layer of the UE is in a logical connection with the RRC layer of the E-UTRAN. If connected, the RRC connection state is called. Since the UE in the RRC connected state has an RRC connection, the E-UTRAN can grasp the existence of the corresponding UE in a cell unit, and thus can effectively control the UE. On the other hand, the UE of the RRC idle state is not identified by the E-UTRAN and is managed by the core network in units of a tracking area (TA), which is a larger area unit than the cell. That is, the presence of the terminal in the RRC idle state is only detected in a large area unit, and in order to receive a normal mobile communication service such as voice or data, it must move to the RRC connected state.

When the user first turns on the terminal, the terminal attempts to make a connection with the public land mobile network (PLMN). The specific PLMN connected can be selected automatically or manually. Here, PLMN refers to a wireless communication system for use by a user on the ground in a vehicle or on foot. Alternatively, the PLMN may indicate all mobile wireless networks using land-based base stations other than satellites. A home PLMN (HPLMN) is a mobile that is contained within an international mobile subscriber identity (IMSI), a unique 15-digit code used for identification of individual users in a global system for mobile communication (GSM) network. The country code (MCN) and the mobile network code (MNC) are the same PLMN.

* Equivalent HPLMN (EHPLMN) list is a PLMN code list that replaces HPLMN codes extracted from IMSI to allow provision of multiple HPLMN codes. The EHPLMN list is stored in a universal subscriber identity module (USIM). The EHPLMN list may include HPLMN codes extracted from IMSI. If the HPLMN code extracted from IMSI is not included in the EHPLMN list, the HPLMN should be treated as a visited PLMN (VPLMN) when selecting a PLMN. VPLMN is a PLMN different from HPLMN and EHPLMN (if present). A registered PLMN (RPLMN) is a PLMN where certain location registration (LR) results occur. In general, in a shared network, an RPLMN is a PLMN defined by PLMN identification of a core network operator that allows LR.

The UE searches for the appropriate cell of the selected PLMN and stays in the RRC idle state in the cell. The UE in the RRC idle state selects a cell capable of providing possible services and adjusts it to a control channel of the selected cell. This process is called "camping on a cell." A terminal camping on a cell may read system information, etc. from the cell, and in most cases, may receive paging information. When camping is completed, the terminal may register its presence in the registration area of the selected cell. This is called location registration (LR). The terminal registers its presence in the registration area regularly or when entering a new tracking area. The registration area refers to any area where the terminal may roam without a location registration procedure.

If the terminal leaves the service area of the cell or finds a more suitable cell, the terminal reselects and camps the most suitable cell in the PLMN. If the new cell is included in another registration area, a location registration request is performed. If the terminal leaves the service area of the PLMN, a new PLMN may be automatically selected or a new PLMN may be manually selected by the user.

The purpose of proceeding camp on the terminal of the RRC idle state is as follows.

1) UE receives system information from PLMN

2) The terminal initially accesses the network through the control channel of the camped cell after initiating a call.

3) Paging message reception: When the PLMN receives a call for the terminal, the PLMN knows the registration area of the cell where the terminal is camped on. Therefore, the PLMN may send a paging message for the terminal through the control channel of all cells in the registration area. Since the terminal is already adjusted for the control channel of the camp-on cell, it may receive a paging message.

4) receive the cell's broadcasting message

Cells camped on by an idle terminal may be classified into several types according to service types. Here, the service type defines the content of the service that the terminal proceeds in the idle state. The cell type is different for each service type provided by the cell. Service types include limited service, normal service, and operator service.

Restricted services are services that can be used in emergencies such as emergency calls, earthquake and tsunami warning systems (ETWS), or commercial mobile alert systems (CMAS). If the terminal cannot find a suitable cell to camp on or if no SIM card is inserted or receives a specific response to the location registration request (eg illegal terminal), the terminal attempts to camp on regardless of the PLMN. Enter the "limited service" state. The restricted service is a service type that can be supported for an acceptable cell. When the terminal finds an allowable cell through cell selection or cell reselection, the terminal is changed to a state "camped on any cell". In the state of camping in an arbitrary cell, the terminal is in an idle state, and the cell selection or cell reselection process is completed, and the cell is selected regardless of the PLMN identity.

A general service is a service corresponding to a public or normal call and can support a suitable cell. A suitable cell is a cell when the terminal belongs to a specific PLMN. For example, the specific PLMN may be any one of a selected PLMN, a registered PLMN, and a PLMN of the equivalent PLMN list.

When the terminal manually or automatically selects a specific PLMN, the specific PLMN is called a selected PLMN. If the terminal belongs to the selected PLMN, the terminal selects a cell in the selected PLMN. The registered PLMN is a PLMN that the network notifies the terminal through a location registration process.

In relation to a suitable cell, if a suitable cell is found through cell selection or cell reselection, the terminal is generally changed to a "camped normally" state. Or, if the terminal does not find a suitable cell through cell selection or cell reselection, the terminal is changed to an "any cell selection" state. The random cell selection state is a state of attempting to find an allowable cell for all PLMNs corresponding to all radio access technologies (RATs) provided by the terminal. If the UE does not find a suitable cell through cell selection or cell reselection, the UE finds an allowable cell in any PLMN in addition to the PLMN corresponding to any suitable cell for all supported RATs.

On the other hand, the operator service is a service that is allowed only to a specific terminal by the operator, it can support a reserved cell (reserved cell).

When the UE in the RRC idle state needs to establish an RRC connection, it establishes an RRC connection with the E-UTRAN through the RRC connection process and transitions to the RRC connected state. There are several cases in which a UE in an RRC idle state needs to establish an RRC connection. For example, an uplink data transmission is necessary due to a user's call attempt, or when a paging message is received from the E-UTRAN, a response message may be transmitted.

Referring to FIG. 2, the terminal selects a PLMN and a RAT to be serviced (S210). The PLMN and the RAT may be selected by the user of the terminal or may be stored in the USIM.

The terminal selects a cell having the largest value as an initial cell among the cells having the measured base station and the signal whose strength or quality is greater than a specific value (S220). The base station periodically receives system information. The specific value refers to a value defined in the system to ensure the quality of the physical signal in data transmission and reception. Therefore, the value may vary depending on the RAT applied.

If the network needs to register, the terminal registers its information (eg, IMSI) in order to receive a service (eg, paging) from the network (S230, S240). The terminal does not register in the network to which the terminal is connected every time the cell is selected. For example, if the system information of the network to be registered (for example, a tracking area identity (TAI) and the information of the network known by the user is different), the network is registered with the network.

The terminal selects another cell that provides better signal characteristics than the cell of the base station to which the terminal is connected if the value of the strength or quality of the signal measured from the base station being served is lower than the value measured from the base station of the adjacent cell. S250). This process is called cell reselection by distinguishing it from the cell selection process such as initial cell selection in step S220. In this case, a time constraint may be set in order to prevent the cell from being frequently reselected according to the change of the signal characteristic.

Next, a procedure of selecting a cell by the terminal will be described in detail.

When the power is turned on or staying in the cell, the terminal selects / reselects a cell of appropriate quality and performs procedures for receiving service.

The UE in the RRC idle state should always be prepared to select a cell of appropriate quality and to receive service through this cell. For example, a terminal that has just been powered on must select a cell of appropriate quality to register with the network. When the terminal in the RRC connected state enters the RRC idle state, the terminal should select a cell to stay in the RRC idle state. As such, the process of selecting a cell satisfying a certain condition in order for the terminal to enter a service standby state such as an RRC idle state is called cell selection. Importantly, since cell selection is performed in a state in which the UE does not currently determine a cell to stay in the RRC idle state, it is most important to select the cell as soon as possible. Therefore, if the cell provides a radio signal quality of a predetermined criterion or more, even if the cell is not a cell providing the best radio signal quality to the terminal, it may be selected during the cell selection process of the terminal.

There are three main cell selection processes.

First, as an initial cell selection process, this process is used by the terminal when the terminal does not have prior information on the radio channel. Accordingly, the terminal searches all radio channels in the EUTRAN band only in a range where the capability of the terminal is allowed to find an appropriate cell. In each channel, the terminal finds the strongest cell. Thereafter, the terminal selects a corresponding cell if it finds a suitable cell satisfying the cell selection criteria.

The second cell selection process is a cell selection process using stored information. In this process, the UE selects a cell by using information stored in the UE for a wireless channel or by using information broadcast from the cell. Therefore, the cell selection may be faster than the initial cell selection process. The UE selects a corresponding cell if it finds a cell that satisfies a cell selection criterion. If a suitable cell that satisfies the cell selection criteria is not found through this process, the UE performs an initial cell selection process.

When the terminal selects a cell that satisfies the cell selection criteria, the terminal receives information necessary for the RRC idle state operation of the terminal in the cell from the system information of the cell. After the UE receives all the information necessary for the RRC idle state operation, it waits in the idle mode to request a service (eg, originating call) to the network or to receive a service (eg, terminating call) from the network.

The third cell selection process is a cell selection process due to leaving of the RRC connection state. This process is as follows. When the terminal is changed from the RRC connected state to the idle state, (a) if the redirectedCarrierInfo is included in the RRC connection release message, the terminal selects a suitable cell according to the redirectedCarrierInfo and attempts to camp on. Here, if the UE does not find a suitable cell, the UE may camp on by searching for any suitable cell according to the designated RAT.

In (a) again, if the redirectedCarrierInfo is not included in the RRC connection release message, the UE searches for a suitable cell in the EUTRA carrier. Here, if the terminal does not find a suitable cell, the terminal starts the selected information cell selection to perform a cell selection process in order to find a suitable cell.

When a UE camping in an arbitrary cell is changed from an RRC connected state to an RRC idle state, (b) if the RRC disconnection message includes a redirecteCarrierInfo, the UE may enter the allowable cell according to the redirectedCarrierInfo. Try to camp on. Here, if the terminal has not found an allowable cell, the terminal may camp on by searching for any allowable cell according to the designated RAT.

In (b) again, if the redirectedCarrierInfo is not included in the RRC connection release message, the UE searches for an allowable cell in the EUTRA carrier. Here, if the UE has not found an acceptable cell, the UE performs a search to find an acceptable cell in any PLMN in any cell selection state.

After the terminal selects a cell through a cell selection process, the strength or quality of a signal between the terminal and the base station may change due to the mobility of the terminal or a change in the wireless environment. Therefore, if the quality of the selected cell is degraded, the terminal may select another cell that provides better quality. When reselecting a cell in this way, a cell that generally provides better signal quality than the currently selected cell is selected. This process is called cell reselection. The cell reselection process has a basic purpose in selecting a cell that generally provides the best quality to a terminal in view of the quality of a radio signal. That is, cells searched by cell reselection are cells that satisfy cell reselection criteria. If a cell of good quality is found, the terminal reselects the cell of good quality. Changing the cell may mean changing the RAT.

Cell reselection may be performed depending on the network, in addition to the above-described quality of the radio signal. According to this, the network may determine the priority for each frequency and notify the terminal. Upon receiving this priority, the UE considers this priority prior to the radio signal quality criteria in the cell reselection process.

Information about absolute priority for different EUTRAN frequencies or inter-RAT frequencies may be transmitted by system information and an RRC disconnection message. The system information may optionally include the priority information. The RRC connection release message may include a dedicated priority. Or, the information about the absolute priority may be received from the other RAT when the UE reselects the inter-RAT cell. This follows the specifications specified in the existing RAT.

If the terminal is provided priority through dedicated signaling, the priority provided through system information is ignored. In other words, upon receiving the priority through the RRC connection release message from the base station, the terminal ignores the priority received from the system information.

When the terminal is camped in an arbitrary cell, the terminal should apply only the priority received through the system information. Therefore, the priority received through dedicated signaling is reserved only unless otherwise specified.

If the terminal generally sets a band other than the currently connected frequency band as a dedicated priority while camping on, the terminal regards the current frequency band as the lowest priority.

In order to perform cell selection in order to initially camp on a specific cell in idle mode or to perform cell reselection for a cell having better performance than the current cell, the power and quality measured by the UE for a specific cell It must be above a certain level. In this case, a power level that may be a reference for cell selection or cell reselection may be expressed as Srxlev. A quality level that may be a criterion for cell selection or cell reselection may be expressed as Squal.

The cell selection criterion used by the UE in cell selection or cell reselection is shown in Equation 1 below.

Srxlev> 0 and Squal> 0

Here, Srxlev = Q _rxlevmeas- (Q _rxlevmin + Q _{rxlevminoffset} )-Pcompensation. Squal = Q _qualmeas- (Q _qualmin + Q _{qualminoffset} ). Description of each parameter is shown in Table 1.

Table 1

Srxlev	Cell Select Receive Level Value (dB)
Squal	Cell selection quality value (dB)
Q _rxlevmeas	Measured Cell Receive Level (RSRP)
Q _qualmeas	Measured Cell Quality (RSRQ)
Q _rxlevmin	Minimum Required Receive Level in Cell (dBm)
Q _qualmin	Minimum Required Quality Level in Cells (dBm)
Q _{rxlevminoffset}	Offset for Q _rxlevmin in Srxlev as a result of the periodic search for higher priority PLMNs during normal camp-on to VPLMN.
Q _{qualminoffset}	Offset for Q _qualmin from Squal, as a result of a periodic search for higher priority PLMNs while typically camped on VPLMN.
Pcompensation	max (P _EMAX -P _PowerClass , 0) (dB)
P _EMAX	Maximum transmit power level (dBm) that UE can use when transmitting on uplink from cell
P _PowerClass	Maximum RF output power according to the power class of the terminal (dBm)

Referring to Equation 1 and Table 1, a cell selection criterion may be satisfied when both Srxlev and Squal are greater than zero. That is, the terminal may determine that the cell has a basic possibility for cell selection when both the RSRP and the RSRQ of the measured cell are above a certain level. In particular, Squal is a parameter corresponding to RSRQ. In other words, Squal is not simply a value related to the magnitude of power measured in a cell, but is calculated in relation to the quality of power. When Squal> 0, the cell selection criterion may be satisfied in terms of the quality of the cell. The measured RSRQ is _equal to or greater than the sum of Q _qualmin and Q _{qualminoffset} to satisfy the cell selection criterion for RSRQ.

Meanwhile, in Table 1, Q _qualmin may have the following meaning.

3 shows that the cell selection range changes according to Q _qualmin .

Referring to FIG. 3, it is assumed that points having the same RSRQ are represented in a circle, but this is for convenience of description. In actual RSRQ measurement, a point having the same RSRQ may not be circular. In FIG. 3, a point at Q _qualmin = A and a point at Q _qualmin = B are indicated, where A> B. If Q _qualmin is set to a relatively small value, such as B, even if the UE measures quality corresponding to a smaller RSRQ, the cell selection criterion may be satisfied. Therefore, the range in which the UE can perform cell selection can be widened. On the other hand, if Q _qualmin is set to a relatively large value such as A, the terminal may satisfy the cell selection criteria only when measuring the quality corresponding to the larger RSRQ. Therefore, the range in which the UE can perform cell selection can be narrowed. If the Q _qualmin is set too large for the base station provider or operator, the size of the cell is reduced. In addition, if the Q _qualmin is made too small, there is a possibility that cell selection or cell reselection is performed in an area that is too wide compared to the actual quality. Accordingly, the quality of service may be degraded because actual camp on or connection is not properly performed. Therefore, it is important to set the appropriate Q _qualmin to inform the terminal.

The cell selection criterion of Equation 1 is a value that is mainly used when the terminal selects a cell, and the reference value may be regarded as zero. The UE may select a corresponding cell when Srxlev and Squal are greater than 0 which is a reference value. Alternatively, the reference value may be a value other than 0 when reselecting or measuring a cell. The UE may reselect a corresponding cell when Srxlev and Squal are greater than a non-zero reference value. These values may be received from the base station through system information such as SIB3 or SIB5. A comparison method for cell reselection will be described later.

Meanwhile, the terminal may receive various parameters used in Equation 1 and Table 1 through system information such as system information block (SIB) 3 and SIB 5. The UE may perform cell selection or cell reselection by using a reference value or a threshold associated with the Squal received through the Squal calculated based on the Q _qualmin and the system information. The UE may perform cell selection or cell reselection in consideration of priorities among cells satisfying the cell selection condition.

Referring to FIG. 4A, the bandwidth of the serving cell E-UTRAN is 10 MHz and the bandwidth of the neighbor cell E-UTRAN is 5 MHz. The first bandwidth and the second bandwidth of 5 MHz used by the neighbor cell are included in the 10 MHz bandwidth of the serving cell. Considering a band that is not available to both sides of the bandwidth of the neighboring cell 5 MHz, the first bandwidth and the second bandwidth that can be actually used may be reduced to about 4.5 MHz, respectively. In this case, the bandwidth gap occurring between the first bandwidth and the second bandwidth of the neighbor cell may be calculated as 5- (4.5 + 4.5) /2=0.5 MHz. If the bandwidth of the serving cell E-UTRAN is 20 MHz and the bandwidth of the neighbor cell E-UTRAN is 10 MHz, the bandwidth gap that occurs between the first bandwidth and the second bandwidth of the neighbor cell is 10- (9 + 9) / It can be calculated as 2 = 2 MHz. This is much larger than 6 RB (= 1.08 MHz), which is the basis of RSRQ measurement.

Referring to FIG. 4B, the bandwidth of the serving cell E-UTRAN is 10 MHz and the bandwidth of the neighbor cell UTRAN is 3.84 MHz. The first bandwidth and the second bandwidth of 3.84 MHz used by neighboring cells are included in the 10 MHz bandwidth of the serving cell. In this case, the bandwidth gap occurring between the first bandwidth and the second bandwidth of the neighbor cell may be calculated as 5- (3.84 + 3.84) /2=1.16 MHz. This is also a value greater than 6 RB.

As described above, when the bandwidths of the serving cell and the neighbor cell of the same channel are different from each other, if the narrowband RSRQ is measured at 6 RB according to the conventional method, interference from the neighbor cell may not be correctly received in the bandwidth gap. That is, when the size of the bandwidth gap is 6 RB or more, it is determined that the amount of interference from the neighboring cell is smaller than the actual amount of interference, and thus RSSI can be calculated less than the actual amount. As a result, the RSRQ can be calculated larger than the actual amount. have. When the UE in the idle mode performs cell selection or cell reselection using the calculated RSRQ, a problem may occur in cell selection or cell reselection. In other words, the cell reselection may occur later than necessary due to an incorrectly measured RSRQ.

Hereinafter, when the UE in the idle mode measures the RSRQ and determines the cell selection quality value based on the measured RSRQ, the cell selection quality value determined based on the narrowband RSRQ is performed. A method of determining a cell selection quality value based on a wideband RSRQ will be described. In the following description, an embodiment of the present invention may be applied when the bandwidth is 10 MHz or more, or when the AllowedMeasBandwidth indicates 50 RB or more.

1) First, when the UE determines the cell selection quality value by measuring the narrowband RSRQ when the system bandwidth is 10 MHz or more, the narrowband RSRQ may be less than the actual value. As described above, RSRQ is defined as N * RSRP / (E-UTRA carrier RSSI). At this time, the RSSI corresponds to the sum of all signals measured by the UE, and also includes interference signals from neighboring cells. However, when the RSSI is measured based on 6 RB when the system bandwidth is 10 MHz or more, the amount of the interference signal from the neighboring cell is determined to be smaller than the actual amount, thereby decreasing the RSSI. Therefore, RSRQ can be calculated to be larger than actual. Therefore, a cell selection quality value can be determined by adding a value capable of correcting this. Equation 2 shows an example of an equation for determining a cell selection quality value according to an embodiment of the present invention.

Squal = Q _qualmeas- (Q _qualmin + Q _{qualmingapoffset} + Q _{qualminoffset} )

Referring to Equation 2, Q _{qualmingapoffset, which} is an offset considering a bandwidth gap, is added when determining a cell selection quality value. That is, the cell selection quality value may be determined smaller than when the cell selection quality value is determined based only on the RSRQ by the offset Q _{qualmingapoffset} . If _{allowedMeasBandwidth} indicates 50 RB or more, if the cell selection quality value is determined by considering only the RSRQ without considering the Q _{qualmingapoffset} , the cell selection quality value does not reflect the measurement error that may occur due to the bandwidth gap. Will be calculated. To this end, in order to correct the distortion in which the RSRQ increases when determining the cell selection quality value, Q _{qualmingapoffset} corresponding to a certain portion of the applied value may be additionally used. This is to solve the problem that occurs when the existing narrowband RSRQ is measured even though allowedMeasBandwidth indicates 50 RB or more.

2) Or, the UE can determine the cell selection quality value by measuring the wideband RSRQ. In the case of a terminal capable of measuring a wideband RSRQ, if the terminal has a system bandwidth of 50 RB or more, the wideband RSRQ can be measured. In the case of measuring the wideband RSRQ, the Squal can be determined by a conventional method. Equation 3 shows another example of the equation for determining the cell selection quality value according to an embodiment of the present invention.

Squal = Q _qualmeas- (Q _qualmin + Q _{qualminoffset} ) and wideband RSRQ measurements

Equation 3 can be used to measure the wideband RSRQ. That is, the equation for determining the existing cell selection quality value may be used as it is, and the cell selection quality value may be determined by applying the same to the broadband.

Equation 4 shows another example of the equation for determining the cell selection quality value according to an embodiment of the present invention.

Squal = Q _qualmeas- (Q _qualmin + Q _{qualmingapoffset} + Q _{qualminoffset} ) and wideband RSRQ measurements

By using Equation 4, the wideband RSRQ can be measured. Q _{qualmingapoffset} = 0.

Referring to FIG. 5, in step S100, the base station transmits a wideband RSRQ measurement indicator to the terminal. In step S110, the UE measures the wideband RSRQ based on the wideband RSRQ measurement indicator.

The base station may transmit a wideband RSRQ measurement indicator to inform the terminal whether wideband RSRQ measurement is possible and / or Q _{qualmingapoffset} . The wideband RSRQ measurement indicator may be broadcast through system information.

Table 2 shows an example of SIB 1 including a wideband RSRQ measurement indicator according to an embodiment of the present invention.

TABLE 2

-ASN1STARTSystemInformationBlockType1 :: = SEQUENCE {… } [[widebandRSRQMeas-r11 ENUMERATED {enabled} OPTIONAL--Cond WB-RSRQ]] CellSelectionInfo-v920 :: = SEQUENCE {q-QualMin-r9 Q-QualMin-r9, q-QualMinOffset-r9 INTEGER (1..8) OPTIONAL-Need OP} CellSelectionInfo-v11 :: = SEQUENCE { q-QualMinGapOffset-r9 Q-QualMinGapOffset-r11, OPTIONAL-Need OP }

Referring to Table 2, the widebandRSRQmeas field indicates a wideband RSRQ measurement indicator. The widebandRSRQmeas field may indicate whether wideband RSRQ measurement is possible. That is, if the terminal is capable of measuring the wideband RSRQ when the value of the widebandRSRQmeas field is set to enable, the terminal measures the wideband RSRQ. The widebandRSRQmeas field may exist only when allowedMeasBandwidth indicates 50 RB or more. In addition, the q-QualminGapOffset field may be transmitted in addition to the widebandRSRQmeas field. The q-QualminGapOffset field indicates an offset for compensating for the difference in RSRQ measurement when the allowedMeasBandwidth indicates 50 RB or more and the UE measures narrowband RSRQ.

Meanwhile, transmitting the wideband RSRQ measurement indicator through the system information may be unnecessary for the terminal that does not use it. Therefore, instead of transmitting the wideband RSRQ measurement indicator through the system information, the terminal allowed to perform the wideband RSRQ measurement in the existing connection mode may be determined to perform the wideband RSRQ measurement even in the idle mode. At this time, when the terminal is changed from the connected mode to the idle mode, the terminal can grasp not only the corresponding cell but also the situation of the cell used by the terminal. That is, the terminal may store information about the cell connected in the connected mode when the change from the connected mode to the idle mode. The UE may determine whether the cell has previously allowed wideband RSRQ measurement in the process of reselection of a specific cell. Therefore, in a cell that allows the wideband RSRQ measurement in the connected mode, the UE may be determined to perform the wideband RSRQ measurement in the idle mode for cell reselection.

Table 3 shows an example of SIB 3 including a wideband RSRQ measurement indicator according to an embodiment of the present invention.

TABLE 3

-ASN1STARTSystemInformationBlockType3 :: = SEQUENCE {… intraFreqCellReselectionInfo SEQUENCE {q-RxLevMin Q-RxLevMin, p-Max P-Max OPTIONAL,-Need OPs-IntraSearch ReselectionThreshold OPTIONAL,-Need OPallowedMeasBandwidth AllowedMeasBandwidth OPTIONAL,-Need OPpresenceAntennaPort1 PresenceAeighennaConfigPort1, NeighborSelectPort N, t-ReselectionEUTRA-SF SpeedStateScaleFactors OPTIONAL widebandRSRQMeas-r11 ENUMERATED {enabled} OPTIONAL-Cond WB-RSRQ -Need OP}, ..., lateNonCriticalExtension OCTET STRING OPTIONAL,-Need OP [[s-IntraSearch-v920 SEQUENCE {s -IntraSearchP-r9 ReselectionThreshold, s-IntraSearchQ-r9 ReselectionThresholdQ-r9} OPTIONAL,-Need OPs-NonIntraSearch-v920 SEQUENCE {s-NonIntraSearchP-r9 ReselectionThreshold, s-NonIntraSearchQ-r9 ReselectionThresholdQ, r9} OP Need-OP QualMin-r9 Q-QualMin-r9 OPTIONAL, -Need OP q-QualMinGapOffset-r9 Q-QualMinGapOffset-r11, OPTIONAL-Need OP threshServingLowQ-r9 ReselectionThresholdQ-r9 OPTIONAL-Need OP]]}

Referring to Table 3, the widebandRSRQmeas field indicates a wideband RSRQ measurement indicator. The widebandRSRQmeas field may indicate whether wideband RSRQ measurement is possible. That is, if the terminal is capable of measuring the wideband RSRQ when the value of the widebandRSRQmeas field is set to enable, the terminal measures the wideband RSRQ. The widebandRSRQmeas field may exist only when allowedMeasBandwidth indicates 50 RB or more. In addition, the q-QualminGapOffset field may be transmitted in addition to the widebandRSRQmeas field. The q-QualminGapOffset field indicates an offset for compensating for the difference in RSRQ measurement when the allowedMeasBandwidth indicates 50 RB or more and the UE measures narrowband RSRQ.

Table 4 shows an example of SIB 5 including a wideband RSRQ measurement indicator according to an embodiment of the present invention.

Table 4

-ASN1STARTSystemInformationBlockType5 :: = SEQUENCE {interFreqCarrierFreqList InterFreqCarrierFreqList, ..., lateNonCriticalExtension OCTET STRING OPTIONAL-Need OP} InterFreqCarrierFreqList :: = SEQUENCE (SIZE (1..maxFreqC) FarrierFrqInfo ValueEUTRA, q-RxLevMin Q-RxLevMin, p-Max P-Max OPTIONAL,-Need OPt-Reselection , presenceAntennaPort1 PresenceAntennaPort1, cellReselectionPriority CellReselectionPriority OPTIONAL, - Need OPneighCellConfig NeighCellConfig, q-OffsetFreq q-OffsetRange DEFAULT dB0, interFreqNeighCellList interFreqNeighCellList OPTIONAL, - Need ORinterFreqBlackCellList InterFreqBlackCellList OPTIONAL, - Need OR ..., widebandRSRQMeas-r11 ENUMERATED {enabled} OPTIONAL -Cond WB-RSRQ [[q-QualMin-r9 Q-QualMin-r9 OPT IONAL,-Need OP q-QualMinGapOffset-r9 Q-QualMinGapOffset-r11, OPTIONAL-Need OP threshX-Q-r9 SEQUENCE {threshX-HighQ-r9 ReselectionThresholdQ-r9, threshX-LowQ-r9 ReselectionThresholdQ-r9} OPTIONAL- Cond RSRQ]]} InterFreqNeighCellList :: = SEQUENCE (SIZE (1..maxCellInter)) OF InterFreqNeighCellInfoInterFreqNeighCellInfo :: = SEQUENCE {physCellId PhysCellId, q-OffsetCell Q-OffsetRange} InterFreqBlackCellList (=). U.C. OF PhysCellIdRange-- ASN1STOP

Referring to Table 4, the widebandRSRQmeas field indicates a wideband RSRQ measurement indicator. The widebandRSRQmeas field may indicate whether wideband RSRQ measurement is possible. That is, if the terminal is capable of measuring the wideband RSRQ when the value of the widebandRSRQmeas field is set to enable, the terminal measures the wideband RSRQ. The widebandRSRQmeas field may exist only when allowedMeasBandwidth indicates 50 RB or more. In addition, the q-QualminGapOffset field may be transmitted in addition to the widebandRSRQmeas field. The q-QualminGapOffset field indicates an offset for compensating for the difference in RSRQ measurement when the allowedMeasBandwidth indicates 50 RB or more and the UE measures narrowband RSRQ.

Meanwhile, the terminal may evaluate the neighbor cells using Srxlev and Squal for cell reselection, and the terminal may set the following additional conditions to prevent unnecessary measurement from being performed.

1) First, if the terminal is srxlev> S _IntraSearchP and Squal> S _IntraSearchQ , the terminal does not perform intra-frequency measurement. Otherwise, the terminal performs intra-frequency measurement.

2) In addition, the UE performs the measurement when the priority of the neighboring cell is higher than the priority of the serving cell for E-UTRAN inter-frequency or inter-RAT. In addition, when the priority of the neighboring cell is equal to or lower than the priority of the serving cell between the E-UTRAN frequencies or between the RATs, the UE is between E-UTRAN frequencies or when Srxlev> S _{nonIntraSearchP} and Squal> S _{nonIntraSearchQ} in the serving cell. No measurements are made between RATs, otherwise measurements are taken between E-UTRAN frequencies or between RATs.

S _IntraSearchQ and S _{nonIntraSearchQ} may be used as a triggering threshold for the Squal determined by the UE. That is, S _IntraSearchQ indicates a Squal threshold for intra-frequency measurements. S _{nonIntraSearchQ} indicates a Squal threshold for measurement between E-UTRAN frequencies or measurement between RATs. S _IntraSearchQ and S _{nonIntraSearchQ} may be transmitted through system information such as SIB3. If the system bandwidth is 10 MHz or more, when performing narrowband measurement as before, the Squal may be distorted and calculated, and thus there is a possibility that the cell reselection may not be performed normally.

In addition, cell reselection criteria between E-UTRAN frequencies and between RATs may be set. Cell reselection criteria between E-UTRAN frequencies and inter-RATs may be _changed by Thresh _{Serving, LowQ} indicating a minimum squal threshold of a serving cell when the UE performs cell reselection at a lower priority frequency or RAT. have. That is, Thresh _{Serving, LowQ} means a threshold value of Squal that can allow cell reselection to be performed at a frequency or RAT having a low priority. Thresh _{Serving, LowQ} can be transmitted via SIB 3.

If Thresh _{Serving, LowQ} is present, the UE satisfies the cell reselection criterion, and if it is more than 1 second after camping on the current serving cell, the UE has a higher priority than the priority of the serving frequency. Reselection can be performed. In this case, a cell having a higher priority (E-UTRAN or UTRAN FDD RAT / frequency) satisfies Squal> Thresh _{X, HighQ} during the time interval Treselection _RAT , or has a higher priority cell (UTRAN TDD RAT / GENRA / CDMA2000). The cell reselection criterion may be satisfied when Srxlev> Thresh _{X, highP} is satisfied during the time interval Treselection _RAT . Thresh _{X, HighQ} indicates a Squal threshold of the corresponding cell when cell reselection is performed with a frequency or RAT having a higher priority than the current serving frequency. That is, Thresh _{X, HighQ} means a threshold value of a frequency or a Squal of the RAT having a high priority compared to the current serving cell. Cell reselection may be performed when Thresh _{X, HighQ} is exceeded for a predetermined time. Thresh _{X, HighQ} may be transmitted over SIB 5. Treselection _RAT is the minimum time that the UE must evaluate each cell for cell reselection.

If Thresh _{Serving, LowQ} does not exist, the UE satisfies the cell reselection criterion and passes to the E-UTRAN frequency or the RAT frequency having a higher priority than the serving frequency after 1 second after camping in the current serving cell. Cell reselection may be performed. In this case, the cell reselection criterion may be satisfied when a frequency or RAT having a higher priority satisfies Srxlev> Thresh _{X, highP} during the time period Treselection _RAT .

In addition, cell reselection for an E-UTRAN frequency having the same priority may be performed in the same manner as setting an intra-frequency ranking.

In addition, when Thresh _{Serving, LowQ} is present, the UE satisfies the cell reselection criterion and when the _camper is present in the current serving cell for at least 1 second, the UE may return to the E-UTRAN frequency or the RAT frequency having a lower priority than the serving frequency. Cell reselection may be performed. At this time, if the serving cell satisfies Squal <Thresh _{Serving, LowQ} and the low priority E-UTRAN or UTRAN FDD RAT / frequency satisfies Squal> Thresh _{X, lowQ} during the time interval Treselection _RAT , or the serving cell during the time interval Treselection _RAT The cell reselection criterion may be satisfied when the cell satisfies Squal <Thresh _{Serving, LowQ} and the E-UTRAN or UTRAN FDD RAT / frequency having a low priority satisfies Srxlev> Thresh _{X, lowP} . Thresh _{X, lowQ} indicates a Squal threshold of the corresponding cell when cell reselection is performed with a frequency or RAT having a lower priority than the current serving frequency. That is, Thresh _{X, lowQ} means a threshold value of a frequency or a Squal of the RAT having a lower priority compared to the current serving cell. Cell reselection may be performed when Thresh _{X, lowQ} is exceeded for a predetermined time. Thresh _{X, lowQ} may be transmitted over SIB 5.

If Thresh _{Serving, LowQ} is not present, the UE satisfies the cell reselection criterion and passes to the E-UTRAN frequency or the RAT frequency having a priority lower than the priority of the serving frequency after 1 second of camping in the current serving cell. Cell reselection may be performed. The time interval Treselection _RAT serving cell for the Srxlev <Thresh _Serving, satisfy _LowP and low priority E-UTRAN or UTRAN FDD RAT / frequency having a rank Srxlev> Thresh _X, be the case satisfied _lowP the cell reselection criteria are met for Can be.

Thresh _{Serving, LowQ} , Thresh _{X, HighQ,} and Thresh _{X, LowQ} are similar values to S _IntraSearchQ and S _{nonIntraSearchQ} described above _, and are compared with the Squal calculated by the UE, and the triggering threshold for the Squal determined by the UE Can be used as If the system bandwidth is 10 MHz or more, when performing narrowband measurement as before, the Squal may be distorted and calculated, and thus there is a possibility that the cell reselection may not be performed normally.

Therefore, according to an embodiment of the present invention, a method of applying an offset to each of the threshold parameters described above when the system bandwidth is 10 MHz or more, or a method of newly defining new threshold parameters corresponding to a broadband system may be proposed. .

Table 5 shows an example of SIB 3 including an offset of a wideband RSRQ measurement indicator and at least one threshold parameter according to an embodiment of the present invention.

Table 5

-ASN1STARTSystemInformationBlockType3 :: = SEQUENCE {… intraFreqCellReselectionInfo SEQUENCE {q-RxLevMin Q-RxLevMin, p-Max P-Max OPTIONAL,-Need OPs-IntraSearch ReselectionThreshold OPTIONAL,-Need OPallowedMeasBandwidth AllowedMeasBandwidth OPTIONAL,-Need OPpresenceAntennaPort1 PresenceAeighennaConfigPort1, NeighborSelectPort N, t-ReselectionEUTRA-SF SpeedStateScaleFactors OPTIONAL widebandRSRQMeas-r11 ENUMERATED {enabled} OPTIONAL-Cond WB-RSRQ -Need OP}, ..., lateNonCriticalExtension OCTET STRING OPTIONAL,-Need OP [[s-IntraSearch-v920 SEQUENCE {s -IntraSearchP-r9 ReselectionThreshold, s-IntraSearchQ-r9 ReselectionThresholdQ-r9 s-IntraSearchQoffset-r11 ReselectionThresholdQ-r9 } OPTIONAL,-Need OPs-NonIntraSearch-v920 SEQUENCE {s-NonIntraSearchP-r9 ReselectionThrestrar-N s-NonIntraSearchQOffset-r11 ReselectionThresholdQ-r9 } OPTIONAL,-Need OPq-QualMin-r9 Q-QualMin-r9 OPTIONAL, -Need OP q-QualMinGapOffset-r9 Q-QualMinGapOffset-r11, OPTIONAL-Nee d OP threshServingLowQ-r9 ReselectionThresholdQ-r9 OPTIONAL-Need OP threshServingLowQOffset-r11 ReselectionThresholdQ-r9 OPTIONAL-Need OP ]]}

Table 5 includes the s-IntraSearchQoffset field, the s-nonIntraSearchQoffset field, and the threshServingLowQOffset field in addition to SIB 3 described in Table 3. The s-IntraSearchQOffset field indicates an offset applied to S _IntraSearchQ , which is a Squal threshold for intra-frequency measurement. That is, the s-IntraSearchQOffset field is an offset in consideration of a squal error that may occur for s _IntraSearchQ when the system bandwidth is 10 MHz or more. The s-IntraSearchQOffset field may be applied when the system bandwidth is 10 MHz, and the terminal measuring the wideband RSRQ may not use it. The s-nonIntraSearchQOffset field indicates an offset applied to S _{nonIntraSearchQ} which is a Squal threshold for inter-E-UTRAN frequency measurement or inter-RAT measurement. That is, the s-nonIntraSearchQOffset field is an offset considering a squal error that may occur for s _{nonIntraSearchQ} when the system bandwidth is 10 MHz or more. The s-nonIntraSearchQOffset field may be applied when the system bandwidth is 10 MHz, and the terminal measuring the wideband RSRQ may not use it. The threshServingLowQOffset field indicates an offset applied to Thresh _{Serving, LowQ} indicating a minimum squal threshold of a serving cell when the UE performs cell reselection at a lower priority frequency or RAT. That is, the threshServingLowQOffset field is an offset considering a squal error that may occur for Thresh _{Serving, LowQ} when the system bandwidth is 10 MHz or more. The threshServingLowQOffset field may be applied when the system bandwidth is 10 MHz, and the UE measuring the wideband RSRQ may not use it. As such, an offset applied to a threshold parameter for a serving cell or a neighbor cell may be indicated.

Table 6 shows an example of SIB 5 including an offset of a wideband RSRQ measurement indicator and at least one threshold parameter according to an embodiment of the present invention.

Table 6

-ASN1STARTSystemInformationBlockType5 :: = SEQUENCE {interFreqCarrierFreqList InterFreqCarrierFreqList, ..., lateNonCriticalExtension OCTET STRING OPTIONAL-Need OP} InterFreqCarrierFreqList :: = SEQUENCE (SIZE (1..maxFreqC) FarrierFrqInfo ValueEUTRA, q-RxLevMin Q-RxLevMin, p-Max P-Max OPTIONAL,-Need OPt-Reselection , presenceAntennaPort1 presenceAntennaPort1, cellReselectionPriority cellReselectionPriority OPTIONAL, - Need OPneighCellConfig NeighCellConfig, q-OffsetFreq q-OffsetRange DEFAULT dB0, interFreqNeighCellList InterFreqNeighCellList OPTIONAL, - Need ORinterFreqBlackCellList InterFreqBlackCellList OPTIONAL, - Need OR ..., widebandRSRQMeas-r11 ENUMERATED {enabled} OPTIONAL -Cond WB-RSRQ [[q-QualMin-r9 Q-QualMin-r9 OPT IONAL,-Need OP q-QualMinGapOffset-r9 Q-QualMinGapOffset-r11, OPTIONAL-Need OP threshX-Q-r9 SEQUENCE {threshX-HighQ-r9 ReselectionThresholdQ- r9, threshX-HighQOffset-r11 ReselectionThresholdQ-r9, threshX-Low -r9 ReselectionThresholdQ-r9 threshX-LowQOffset-r11 ReselectionThresholdQ-r9, } OPTIONAL-Cond RSRQ]]} InterFreqNeighCellList :: = SEQUENCE (SIZE (1..maxCellInter)) OFInterFreqNeighCellInfoInterFreqNeighCellInfoCellInfoPick -OffsetRange} InterFreqBlackCellList :: = SEQUENCE (SIZE (1..maxCellBlack)) OF PhysCellIdRange-- ASN1STOP

Table 6 is a form including the threshX-HighQOffset field and the threshX-LowQOffset field in addition to SIB 5 described in Table 4. The threshX-HighQOffset field indicates an offset applied to Thresh _{X, HighQ} , which is a Squal threshold of a corresponding cell when cell reselection is performed with a frequency or RAT having a higher priority than the current serving frequency. That is, the threshX-HighQOffset field is an offset considering a squal error that may occur for Thresh _{X and HighQ} when the system bandwidth is 10 MHz or more. The threshX-HighQOffset field may be applied when the system bandwidth is 10 MHz, and the terminal measuring the wideband RSRQ may not use it. The threshX-LowQOffset field indicates an offset applied to Thresh _{X, LowQ} , which is a Squal threshold of a corresponding cell when cell reselection is performed at a frequency or RAT having a lower priority than a current serving frequency. That is, the threshX-LowQOffset field is an offset considering Squal errors that may occur for Thresh _{X and LowQ} when the system bandwidth is 10 MHz or more. The threshX-LowQOffset field may be applied when the system bandwidth is 10 MHz, and the terminal measuring the wideband RSRQ may not use it. As such, an offset applied to a threshold parameter for a serving cell or a neighbor cell may be indicated.

Table 7 shows an example of SIB 3 including a wideband RSRQ measurement indicator and at least one threshold parameter corresponding to a wideband system according to an embodiment of the present invention.

TABLE 7

-ASN1STARTSystemInformationBlockType3 :: = SEQUENCE {… intraFreqCellReselectionInfo SEQUENCE {q-RxLevMin Q-RxLevMin, p-Max P-Max OPTIONAL,-Need OPs-IntraSearch ReselectionThreshold OPTIONAL,-Need OPallowedMeasBandwidth AllowedMeasBandwidth OPTIONAL,-Need OPpresenceAntennaPort1 PresenceAeighennaConfigPort1, NeighborSelectPort N, t-ReselectionEUTRA-SF SpeedStateScaleFactors OPTIONAL widebandRSRQMeas-r11 ENUMERATED {enabled} OPTIONAL-Cond WB-RSRQ -Need OP}, ..., lateNonCriticalExtension OCTET STRING OPTIONAL,-Need OP [[s-IntraSearch-v920 SEQUENCE {s -IntraSearchP-r9 ReselectionThreshold, s-IntraSearchQ-r9 ReselectionThresholdQ-r9 s-IntraSearchQwb-r11 ReselectionThresholdQ-r11 } OPTIONAL,-Need OPs-NonIntraSearch-v920 SEQUENCE {s-NonIntraSearchP-r9 ReselectionThrestrar-N s-NonIntraSearchQwb-r11 ReselectionThresholdQ-r11 } OPTIONAL,-Need OPq-QualMin-r9 Q-QualMin-r9 OPTIONAL, -Need OP q-QualMinGapOffset-r9 Q-QualMinGapOffset-r11, OPTIONAL-Need OP t hreshServingLowQ-r9 ReselectionThresholdQ-r9 OPTIONAL-Need OP threshServingLowQwb-r11 ReselectionThresholdQ-r11 OPTIONAL-Need OP ]]}

Table 7 shows that in SIB 3 described in Table 5, the s-IntraSearchQoffset field, the s-nonIntraSearchQoffset field, and the threshServingLowQOffset field are replaced with the s-IntraSearchQwb field, the s-nonIntraSearchQwb field, and the threshServingLowQwb field, respectively. The s-IntraSearchQwb field indicates a Squal threshold for intra-frequency measurement when the system bandwidth is 10 MHz or more. That is, the s-IntraSearchQwb field may replace S _IntraSearchQ for a terminal performing wideband RSRQ measurement. The s-nonIntraSearchQwb field indicates a Squal threshold for measuring between E-UTRAN frequencies or measuring between RATs when the system bandwidth is 10 MHz or more. That is, the s-nonIntraSearchQwb field may replace S _{nonIntraSearchQ} for a terminal performing wideband RSRQ measurement. The threshServingLowQwb field indicates the minimum Squal threshold of the serving cell when the UE performs cell reselection at a lower priority frequency or RAT when the system bandwidth is 10 MHz or more. That is, the threshServingLowQwb field may replace Thresh _{Serving, LowQ} for a UE performing wideband RSRQ measurement. As such, the threshold parameters corresponding to the broadband system and newly defined serving cells or neighbor cells may be indicated.

Table 8 shows an example of SIB 5 including a wideband RSRQ measurement indicator and at least one threshold parameter corresponding to a wideband system according to an embodiment of the present invention.

Table 8

-ASN1STARTSystemInformationBlockType5 :: = SEQUENCE {interFreqCarrierFreqList InterFreqCarrierFreqList, ..., lateNonCriticalExtension OCTET STRING OPTIONAL-Need OP} InterFreqCarrierFreqList :: = SEQUENCE (SIZE (1..maxFreqC) FarrierFrqInfo ValueEUTRA, q-RxLevMin Q-RxLevMin, p-Max P-Max OPTIONAL,-Need OPt-Reselection , presenceAntennaPort1 PresenceAntennaPort1, cellReselectionPriority CellReselectionPriority OPTIONAL, - Need OPneighCellConfig NeighCellConfig, q-OffsetFreq Q-OffsetRange DEFAULT dB0, interFreqNeighCellList interFreqNeighCellList OPTIONAL, - Need ORinterFreqBlackCellList InterFreqBlackCellList OPTIONAL, - Need OR ..., widebandRSRQMeas-r11 ENUMERATED {enabled} OPTIONAL -Cond WB-RSRQ [[q-QualMin-r9 Q-QualMin-r9 OPT IONAL,-Need OP q-QualMinGapOffset-r9 Q-QualMinGapOffset-r11, OPTIONAL-Need OP threshX-Q-r9 SEQUENCE {threshX-HighQ-r9 ReselectionThresholdQ- r9, threshX-HighQwb-r11 ReselectionThresholdQ-row , threshX-Low -r9 ReselectionThresholdQ-r9 threshX-LowQwb-r11 ReselectionThresholdQ-r11, } OPTIONAL-Cond RSRQ]]} InterFreqNeighCellList :: = SEQUENCE (SIZE (1..maxCellInter)) OF InterFreqNeighCellInfoInterFreq, NeighCellInfoCellInfoSelect = CellInfo Q-OffsetRange} InterFreqBlackCellList :: = SEQUENCE (SIZE (1..maxCellBlack)) OF PhysCellIdRange-- ASN1STOP

Table 8 shows that the threshX-HighQOffset field and threshX-LowQOffset field are replaced with the threshX-HighQwb field and threshX-LowQwb field, respectively, in SIB 5 described in Table 6. The threshX-HighQOffset field indicates the Squal threshold of the corresponding cell when cell reselection is performed at a frequency or RAT having a higher priority than the current serving frequency when the system bandwidth is 10 MHz or more. That is, the threshX-HighQOffset field may replace Thresh _{X and HighQ} for the UE that performs wideband RSRQ measurement. The threshX-LowQOffset field indicates a Squal threshold of the corresponding cell when cell reselection is performed at a frequency or RAT having a lower priority than the current serving frequency when the system bandwidth is 10 MHz or more. That is, the threshX-LowQOffset field may replace Thresh _{X, LowQ} for a UE performing wideband RSRQ measurement. As such, the threshold parameters corresponding to the broadband system and newly defined serving cells or neighbor cells may be indicated.

In step S400, the terminal receives a wideband RSRQ measurement indicator from the base station. In step S410, the terminal receives from the base station at least one threshold parameter corresponding to the at least one offset or broadband system applied to the threshold parameters. In step S420, the UE measures the RSRQ based on the wideband RSRQ measurement indicator. In step S430, the UE determines a cell selection quality value based on the measured RSRQ and the at least one offset or the at least one threshold parameter.

The base station 800 includes a processor 810, a memory 820, and an RF unit 830. Processor 810 implements the proposed functions, processes, and / or methods. Layers of the air interface protocol may be implemented by the processor 810. The memory 820 is connected to the processor 810 and stores various information for driving the processor 810. The RF unit 830 is connected to the processor 810 to transmit and / or receive a radio signal.

The terminal 900 includes a processor 910, a memory 920, and an RF unit 930. The processor 910 implements functions, processes and / or methods in accordance with an embodiment of the present invention. Layers of the air interface protocol may be implemented by the processor 910. The memory 920 is connected to the processor 910 and stores various information for driving the processor 910. The RF unit 930 is connected to the processor 910 to transmit and / or receive a radio signal.

Processors

810 and 910 may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processing devices. The

memory

820, 920 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium, and / or other storage device. The

RF unit

830 and 930 may include a baseband circuit for processing a radio signal. When the embodiment is implemented in software, the above-described technique may be implemented as a module (process, function, etc.) for performing the above-described function. The module may be stored in the

memory

820, 920 and executed by the

processor

810, 910. The

memories

820 and 920 may be inside or outside the

processors

810 and 910, and may be connected to the

processors

810 and 910 by various well-known means.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

Claims

A method for determining a cell selection quality value (Squal) by a terminal in a wireless communication system,

Receiving a wideband RSRQ measurement indicator and a bandwidth gap offset indicating whether the terminal can measure a wideband reference signal received quality (RSRQ) from a base station,

Measure an RSRQ based on the wideband RSRQ measurement indicator;

Determining the cell selection quality value based on the measured RSRQ.
The method of claim 1,

Wherein the wideband RSRQ measurement indicator and bandwidth gap offset are received via system information.
The method of claim 2,

The system information is at least one of the system information block (SIB) 1, SIB3 or SIB5.
The method of claim 1,

When the wideband RSRQ measurement indicator indicates that the terminal can measure a wideband RSRQ,

The measured RSRQ is a wideband RSRQ,

The cell selection quality value is determined by the following equation.

Squal = Q qualmeas- (Q qualmin + Q qualminoffset )

Where Squal is the cell selection quality value, Q qualmeas is the wideband RSRQ, Q qualmin is the minimum required quality level (dBm) in the cell, and Q qualminoffset indicates an offset from the Squal to the Qqualmin.
The method of claim 1,

If the wideband RSRQ measurement indicator indicates that the terminal can not measure the wideband RSRQ,

The measured RSRQ is a narrowband RSRQ,

The cell selection quality value is determined by the following equation.

Squal = Q qualmeas- (Q qualmin + Q qualmingapoffset + Q qualminoffset )

Where Squal is the cell selection quality value, Q qualmeas is the wideband RSRQ, Q qualmin is the minimum required quality level in dBm of the cell, Q qualmingapoffset is the bandwidth gap offset, and Q qualminoffset is the Squal. It indicates an offset with respect to the Qqualmin.
The method of claim 1,

Receiving from the base station at least one offset applied to a threshold parameter compared to the cell selection quality value.
The method of claim 6,

The at least one offset is an offset applied to S IntraSearchQ , which is a Squal threshold for intra-frequency measurement, an evolved universal terrestrial radio access network (E-UTRAN) inter-frequency measurement or RAT ( an offset applied to S nonIntraSearchQ , a Squal threshold for measurement between radio access technologies, and a Thresh indicating a minimum Squal threshold of a serving cell when the UE performs cell reselection with a lower priority frequency or RAT And at least one of an offset applied to Serving, LowQ .
The method of claim 6,

The at least one offset is a lower priority than the current serving frequency and an offset applied to Thresh X, HighQ which is the Squal threshold of the cell when performing cell reselection with a frequency or RAT having a higher priority than the current serving frequency. And performing at least one of an offset applied to Thresh X, LowQ , which is a Squal threshold of the cell, when performing cell reselection with a frequency or RAT having a rank.
The method of claim 1,

Receiving from the base station at least one newly defined threshold parameter compared to the cell selection quality value and corresponding to a wireless communication system having a system bandwidth of at least 10 MHz.
The method of claim 9,

The at least one threshold parameter includes a cell reselection using a squal threshold for intra-frequency measurements, a squal threshold for inter-EAT frequency measurements or inter-RAT measurements, and a frequency or RAT at which the UE has a lower priority. Performing at least one of a minimum Squal threshold of the serving cell.
The method of claim 9,

The at least one threshold parameter is a frequency or RAT having a lower priority than the Squal threshold and the current serving frequency of the corresponding cell when performing cell reselection at a frequency or RAT having a higher priority than the current serving frequency. And at least one of the Squal thresholds of the cells when performing cell reselection.
The method of claim 1,

And performing cell selection or cell reselection to a neighbor cell when the cell selection quality value satisfies a cell selection criterion.
RF (radio frequency) unit for transmitting or receiving a radio signal; And

Including a processor connected to the RF unit,

The processor,

Receiving a wideband RSRQ measurement indicator and a bandwidth gap offset indicating whether the terminal can measure a wideband reference signal received quality (RSRQ) from a base station,

Measure an RSRQ based on the wideband RSRQ measurement indicator;

And configured to determine a cell selection quality value based on the measured RSRQ.
The method of claim 13,

And the wideband RSRQ measurement indicator and bandwidth gap offset are received through system information.
The method of claim 14,

The system information is at least one of the system information block (SIB) 1, SIB3 or SIB5.
A method for supporting determination of a cell selection quality value (Squal) by a base station in a wireless communication system,

Transmitting a wideband RSRQ measurement indicator and a bandwidth gap offset indicating whether the terminal can measure a wideband reference signal received quality (RSRQ) to the terminal,

The terminal,

Measure an RSRQ based on the wideband RSRQ measurement indicator;

Determining the cell selection quality value based on the measured RSRQ.
The method of claim 16,

Wherein the wideband RSRQ measurement indicator and bandwidth gap offset are transmitted via system information.
The method of claim 17,

The system information is at least one of the system information block (SIB) 1, SIB3 or SIB5.
The method of claim 16,

When the wideband RSRQ measurement indicator indicates that the terminal can measure a wideband RSRQ,

The measured RSRQ is a wideband RSRQ,

The cell selection quality value is determined by the following equation.

Squal = Q qualmeas- (Q qualmin + Q qualminoffset )

However, the Squal is the offset for the Q qualmin in the cell selection quality value, the Q qualmeas is the broadband RSRQ, the Q qualmin is the minimum required quality level (dBm) of the cell), the Q qualminoffset is the Squal Instruct.
The method of claim 16,

If the wideband RSRQ measurement indicator indicates that the terminal can not measure the wideband RSRQ,

The measured RSRQ is a narrowband RSRQ,

The cell selection quality value is determined by the following equation.

Squal = Q qualmeas- (Q qualmin + Q qualmingapoffset + Q qualminoffset )

Where Squal is the cell selection quality value, Q qualmeas is the wideband RSRQ, Q qualmin is the minimum required quality level in dBm of the cell, Q qualmingapoffset is the bandwidth gap offset, and Q qualminoffset is the Squal. It indicates an offset with respect to the Q qualmin .