The present disclosure relates to a wireless communication system that controls communication for improving coverage.
Background technology
[0002]
　In the 3rd Generation Partnership Project (3GPP), technology is being standardized to improve communication quality deterioration due to the rapid increase in mobile traffic in recent years and to realize even higher speed communication. In addition, technology is being standardized to avoid an increase in control signaling load due to connection to the Long Term Evolution (LTE) network or LTE-Advanced network of a huge number of Machine to Machine (M2M) terminals expected in the future. .. Here, the M2M terminal refers to a terminal that communicates without human intervention, for example. M2M terminals are installed in various devices such as machines (eg, vending machines, gas meters, electric meters, automobiles, railroad vehicles, ships) and sensors (eg, sensors related to environment, agriculture, traffic, etc.). In LTE and LTE-Advanced, communication by M2M terminals is called Machine Type Communication (MTC), and terminals that perform MTC are called MTC terminals (MTC User Equipment (MTC UE)).
[0003]
　M2M service providers need to distribute a huge number of M2M terminals to the market, but there is a limit to the cost per M2M terminal. For this reason, M2M terminals are required to be mounted at low cost, to be able to communicate with low power consumption, and the like. In addition, as one use case of MTC UE, it is assumed that communication is performed while being fixedly or statically installed in a building (for example, in a building). In this case, the radio quality of the MTC UE may always be low, compared to regular UEs (eg, mobile phones, smartphones, tablet computers, notebooks / personal computers (notebook PCs)) that are generally mobile. Technology for improving coverage is required. In addition, functional restrictions for cost reduction include, for example, a small maximum transmission power, a small number of receiving antennas (eg, only one receiving antenna), and a higher-order modulation method (eg, 64 quadrature amplitude modulation (64QAM)). It is possible that the radio bandwidth available is narrow (eg, 1.4 MHz), which reduces the maximum transmission rate of the MTC UE.
[0004]
　Therefore, in 3GPP, the technology for improving or enhancing the communication characteristics (that is, coverage) of MTC UE, which is usually expected to be inferior to that of UE, is standardized (non-patented). Document 1). The following describes an example of the technology for improving the coverage of MTC UE under consideration in 3GPP. The coverage improvement technology (coverage improvement process) for MTC UE described below can also be said to be a process for improving or improving the communication characteristics or communication quality of MTC UE. The states of the UE that apply these special coverage enhancement technologies are Coverage Enhancement (CE) Mode, Coverage Extension (CE) Mode, and Enhanced Coverage Mode (Enhanced Coverage Mode). It is called ECM)), or Extended Coverage Mode (ECM).
[0005]
　The characteristics improved by the coverage improvement technology are the reception characteristics of the Physical Broadcast Channel (PBCH), the transmission characteristics of the Physical Random Access Channel (PRACH) preamble (that is, the detection characteristics in the radio base station (evolved NodeB (eNB))), and the Physical Downlink. There are control channel (PDCCH) reception characteristics, physical downlink shared channel (PDSCH) reception characteristics, physical uplink control channel (PUCCH) transmission characteristics, physical uplink shared channel (PUSCH) transmission characteristics, and the like. The PBCH is a downlink notification channel used for transmitting common notification information in the cell by the eNB. PRACH is an uplink physical channel used for initial access (ie, random access) to eNB by UE. The PDCCH is a downlink physical channel used for transmitting downlink data scheduling information (DL assignment) and uplink data radio resource allocation information (UL grant) by, for example, eNB. PDSCH is a downlink physical channel used to receive system information and data by the UE. PUSCH is an uplink physical channel used for data transmission by the UE.
[0006]
　One of the processes studied to improve the reception characteristics of PBCH is to repeat the transmission of the broadcast information by PBCH a predetermined number of times more than usual (see Non-Patent Document 2). One of the processes studied to improve the transmission characteristics of PRACH is to repeat the transmission of PRACH (that is, preamble) a predetermined number of times (see Non-Patent Document 3). Further, one of the processes studied to improve the reception characteristics of PDSCH and the transmission characteristics of PUCCH and PUSCH is to repeatedly transmit PDSCH, PUCCH, and PUSCH over a plurality of subframes (non-patented). See Reference 4). Furthermore, one of the processes being studied to improve the reception characteristics of M-PDCCH, which is a PDCCH that transmits L1 / L2 control information for MTC UE, is to repeatedly transmit M-PDCCH over multiple subframes. That is. It is expected that these processes will improve the communication characteristics of the MTC UE, which is expected to be worse than the normal UE. When downlink data is scheduled by repeated transmission of M-PDCCH, it is considered that the data is transmitted in a subframe after the subframe in which the last repeated transmission of M-PDCCH is performed. .. Further, it is also considered to include the number of repetitions of the M-PDCCH (the number of repetitions actually scheduled to be performed) in the downlink control information (DL Control Information) included in the M-PDCCH.
[0007]
　The number of transmission repetitions and the number of reception repetitions required for improving communication characteristics depend on the location where each MTC UE is installed, and the path loss between each MTC UE and eNB. Therefore, coverage enhancement techniques provide multiple coverage enhancement (CE) levels. Coverage enhancement (CE) levels are sometimes referred to as enhanced coverage levels, coverage extension levels, extended coverage levels, or repetition levels (eg, PRACH repetition levels). Further, a one-to-one relationship or a predetermined relative relationship may be preset between the CE level and the Repetition level.
[0008]
　For example, coverage enhancement techniques provide three CE levels in addition to normal coverage (zero coverage extension). Multiple CE levels are associated with different transmission and reception iterations. The number of transmission iterations and reception iterations used at higher CE levels is greater than those used at lower CE levels. Each MTC UE is assigned a higher CE level as the propagation loss between the MTC UE and the eNB increases. In some implementations, the MTC UE measures the Reference Signal Received Power (RSRP) or the estimated propagation loss between the MTC UE and the eNB, and the measured RSRP or propagation. The required CE level is determined (estimated) based on the loss, and the random access preamble (RACH) preamble is transmitted according to the maximum number of transmission repetitions associated with the determined CE level (see Patent Document 1). ..
Prior art literature
Patent documents
[0009]
Patent Document 1: International Publication No. 2015/021315
Non-patent literature
[0010]
Non-Patent Document 1: 3GPP TR 36.888 V12.0.0 (2013-06), “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Study on provision of low-cost Machine-Type Communications (MTC) User Equipments (UEs) based on LTE (Release 12) ”, June 2013
Non-Patent Document 2: 3GPP R1-135943, Vodafone,“ Way Forward on P-BCH for MTC enhanced coverage ”, 3GPP TSG RAN WG1 # 75, San Francisco, USA, 11 -15 November 2013
Non-Patent Document 3: 3GPP R1-135944, Vodafone, “Way Forward on PRACH for MTC enhanced coverage”, 3GPP TSG RAN WG1 # 75, San Francisco, USA, 11-15 November 2013
Non-Patent Document 4: 3GPP R1-136001, Vodafone et al. “Way forward on PDCCH, PDSCH, PUCCH and PUSCH for MTC enhanced coverage”, 3GPP TSG RAN WG1 # 75, San Francisco, USA, 11-15 November 2013
Outline of the invention
Problems to be solved by the invention
[0011]
　The eNB needs to inform MTC UEs that support coverage improvement technologies of multiple CE-level radio resource settings. For example, the eNB sets the radio resource settings for initial access (ie, random access) by the idle MTC UE to the system information (ie, System Information Block x-bis (SIB x-bis)) for the MTC UE, for example, SIB. Include in 1-bis or SIB2-bis, and transmit in the cell. If the system information had to explicitly include multiple radio resource settings for multiple CE levels, the data size of the system information would increase.
[0012]
　One of the objectives to be achieved by the embodiments disclosed herein is the data size required for the base station to inform the radio terminal of multiple radio resource settings for multiple coverage improvement levels (ie, It is to provide devices, methods, and programs that contribute to reducing signaling overhead. It should be noted that this object is only one of the purposes that the plurality of embodiments disclosed herein seek to achieve. Other objectives or issues and novel features will be apparent from the description or accompanying drawings herein.
Means to solve problems
[0013]
　In the first aspect, the base station includes a memory and at least one processor coupled to the memory. The at least one processor is configured to transmit a first value associated with a normal coverage or first coverage improvement level for the first radio resource configuration information element and information about the transform factor to the radio terminal. Has been done. The value of the conversion factor obtained from the information about the conversion factor is for deriving a second value associated with the second coverage improvement level for the first radio resource setting information element from the first value. Used by the wireless terminal.
[0014]
　In the second aspect, the method in the base station provides a wireless terminal with a first value associated with a normal coverage or first coverage improvement level for the first radio resource configuration information element and information about the transforming factor. Including sending to. The value of the conversion factor obtained from the information about the conversion factor is for deriving a second value associated with the second coverage improvement level for the first radio resource setting information element from the first value. Used by the wireless terminal.
[0015]
　In a third aspect, the wireless terminal comprises a memory and at least one processor coupled to the memory. The at least one processor is configured to execute at least one module. The at least one module includes a receiving module and a computing module. The receiving module is configured to receive from the base station a first value associated with a normal coverage or a first coverage improvement level for the first radio resource configuration information element. The calculation module derives a second value associated with a second coverage improvement level for the first radio resource configuration information element by transforming the first value using the value of the transform factor. It is configured to do so.
[0016]
　In a fourth aspect, the method in the wireless terminal is to (a) receive from the base station a first value associated with a normal coverage or a first coverage improvement level for the first radio resource configuration information element. , And (b) by converting the first value using the value of the transforming factor, the second value associated with the second coverage improvement level for the first radio resource setting information element is derived. Including to do.
[0017]
　In a fifth aspect, the program includes instructions (software code) for causing the computer to perform the method according to the second or fourth aspect described above when loaded into the computer.
The invention's effect
[0018]
　According to the above aspect, a device that contributes to reducing the data size (ie, signaling overhead) required for a base station to inform a radio terminal of multiple radio resource settings for multiple coverage improvement levels. Methods and programs can be provided.
A brief description of the drawing
[0019]
FIG. 1 is a diagram showing a configuration example of a wireless communication network according to some embodiments.
FIG. 2 is a sequence diagram showing an example of a system information transmission operation according to the first embodiment.
[Fig. 3] Fig. 3 is a diagram showing an example of repeated transmission of a RACH preamble.
[Fig. 4] Fig. 4 is a diagram showing an example of the value of the radio resource setting information element for a plurality of CE levels.
FIG. 5 is a flowchart showing an example of the operation of the wireless terminal according to the first embodiment.
FIG. 6 is a diagram showing a first example of calculation for deriving a radio resource setting information element by a radio terminal according to the first embodiment.
FIG. 7 is a diagram showing a second example of calculation for deriving a radio resource setting information element by a radio terminal according to the first embodiment.
FIG. 8 is a diagram showing a third example of calculation for deriving a radio resource setting information element by a radio terminal according to the first embodiment.
FIG. 9 is a diagram showing a fourth example of calculation for deriving a radio resource setting information element by a radio terminal according to the first embodiment.
FIG. 10 is a diagram showing an example of a random access procedure according to the first embodiment.
FIG. 11 is a block diagram showing a configuration example of a wireless terminal according to some embodiments.
FIG. 12 is a block diagram showing a configuration example of a base station according to some embodiments.
Mode for carrying out the invention
[0020]
　Hereinafter, specific embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are designated by the same reference numerals, and duplicate explanations are omitted as necessary for the sake of clarity of explanation.
[0021]
　The plurality of embodiments described below may be implemented independently or in combination as appropriate. These plurality of embodiments have novel features that differ from each other. Therefore, these plurality of embodiments contribute to solving different purposes or problems, and contribute to different effects.
[0022]
　The plurality of embodiments shown below will be described mainly for the Evolved Packet System (EPS) containing LTE and SAE (System Architecture Evolution). However, these embodiments are not limited to EPS, but other mobile communication networks or systems such as 3GPP UMTS, 3GPP2 CDMA2000 system (1xRTT, HRPD (High Rate Packet Data)), global system for mobile communications (1xRTT, HRPD (High Rate Packet Data)), global system for mobile communications (1xRTT, HRPD (High Rate Packet Data)) It may be applied to GSM®) / General packet radio service (GPRS) systems, WiMAX systems, and the like.
[0023]

　FIG. 1 shows a configuration example of a wireless communication network according to some embodiments including the present embodiment. In the example of FIG. 1, the wireless communication network includes one or more wireless terminals (ie, MTC UE) 1 and a base station (eNB) 2. Each MTC UE1 has at least one radio transceiver and is configured to perform cellular communication with the eNB2. The eNB 2 is configured to manage the cell 21 and perform cellular communication with each of a plurality of MTC UE 1s using cellular communication technology (eg, Evolved Universal Terrestrial Radio Access (E-UTRA) technology).
[0024]
　The eNB 2 shown in FIG. 1 may be a Baseband Unit (BBU) used in a Centralized Radio Access Network (C-RAN) architecture. In other words, the eNB 2 shown in FIG. 1 may be a RAN node connected to one or more Remote Radio Heads (RRHs). In some implementations, eNB2 as a BBU is responsible for control plane processing and user plane digital baseband signal processing. RRH, on the other hand, is responsible for analog Radio Frequency (RF) signal processing (eg, frequency conversion and signal amplification). C-RAN is sometimes called Cloud RAN. BBU is also sometimes referred to as Radio Equipment Controller (REC) or Data Unit (DU). RRH is sometimes referred to as Radio Equipment (RE), Radio Unit (RU), or Remote Radio Unit (RRU).
[0025]
　In the example of FIG. 1, since the MTC UE1A is farther from the eNB2 than the MTC UE1B, it is assumed that the propagation loss is large and the radio quality is deteriorated. The MTC UE1C is installed inside a building (for example, a building), and it is expected that the wireless quality will deteriorate compared to when it is installed outdoors. Further, if each MTC UE1 has only limited capabilities or functions as compared with UEs that perform human type communication such as voice call and web browsing, for example, smartphones and tablet computers, the deterioration of wireless quality is more remarkable. Is expected to be. Therefore, the MTC UE1 according to the present embodiment supports the above-mentioned coverage improvement technique.
[0026]
　As described above, repeated DL transmissions, such as system information, M-PDCCH, and PDSCH repeated transmissions, can be used to improve downlink (DL) cell coverage. Repeated UL transmissions, RACH preambles, PUCCH, and repeated PUSCH transmissions can be used to improve uplink (UL) cell coverage.
[0027]
　MTC UE1 may support multiple CE modes (or ECMs). In some implementations, MTC UE1 may support CE modes (or ECMs) for the RRC_IDLE state and another CE modes (or ECMs) for the RRC_CONNECTED state. Further or instead, MTC UE1 may support multiple CE modes (or ECMs) for the RRC_IDLE state, or may support multiple CE modes (or ECMs) for the RRC_CONNECTED state. good. In some implementations, multiple levels of valuation improvement are defined for each CE mode (or each ECM). Further or instead, in some implementations, multiple CE modes provide different levels of coverage improvement from each other.
[0028]
　FIG. 2 shows an example (process 200) of the system information transmission operation according to the present embodiment. In step 201, the eNB 2 transmits system information (eg, SIB1-bis, SIB2-bis) in cell 21. The eNB 2 may repeatedly transmit system information (SIB1bis, SIB2-bis) according to the coverage improvement setting for DL ​​in cell 21.
[0029]
　The system information transmitted in step 201 explicitly or implicitly indicates that the cell supports the coverage enhancement solution, and the control information required for the coverage enhancement technology (Coverage enhancement configuration). ) Is included. In particular, the system information is associated with the normal coverage, zero coverage extension for the first radio resource configuration information element (IE) or the first coverage improvement (CE) level (eg, CE level 1). (Hereinafter referred to as "base value"). The first radio resource setting IE is an IE that needs to be set to a different value for each CE level. For example, the first radio resource configuration IE may relate to at least one of UL messages, UL physical channels, DL messages, and DL physical channels that are repeatedly transmitted in a random access procedure.
[0030]
　In some implementations, the first radio resource configuration IE may include at least one of the plurality of IEs for the RACH configuration listed below:
· numberOfRA-Preambles;
· maxNumPreambleAttemptCE;
· numRepetitionPerPreambleAttempt;
· ra- ResponseWindowSize;
・ mac-ContentionResolutionTimer;
・ maxHARQ-Msg3Tx; and
・ numRepetitionPerRA-Response.
[0031]
　“NumberOfRA-Preambles” IE indicates the total number of random access preambles (RACH preambles) that can be used for contention based random access. “MaxNumPreambleAttemptCE” IE indicates the maximum number of PRACH attempt attempts (per CE level). “NumRepetitionPerPreambleAttempt” IE indicates the number of repeats of preamble transmission per PRACH attempt (for each CE level). “Ra-ResponseWindowSize” IE indicates the duration of the random access (RA) response window. The “mac-ContentionResolutionTimer” IE receives the third message (Msg3) of the random access procedure, that is, the Medium Access Control (MAC) Contention Resolution message for RA Contention Resolution from eNB2 after sending the RRC Connection Request message to eNB2. Indicates the timer value of the MAC contention resolution timer for waiting for. “MaxHARQ-Msg3Tx” IE is the hybrid automatic repeat of the third message (Msg3) of the random access procedure, that is, the RRC Connection Request message. Indicates the maximum number of Request (HARQ) retransmissions. “NumRepetitionPerRA-Response” IE is the second message (Msg2) of the random access procedure, that is, the number of repetitions of M-PDCCH transmission (per CE level) used to send the random access response (RAR) message, or RAR. Indicates the number of times the message is sent repeatedly. Note that these IE names are examples, and other names may be used for these IEs.
[0032]
　FIG. 3 shows an example of repeated transmission of the RACH preamble performed by MTC UE1 that supports the coverage improvement technology. In the example of FIG. 3, the MTC UE1 repeats four preamble transmissions per PRACH attempt and executes a maximum of 20 PRACH attempts. If MTC UE1 fails one attempt, it increases the transmission power of the RACH preamble according to the power ramping scheme and starts the next attempt.
[0033]
　FIG. 4 shows an example of the values ​​of the radio resource configuration information elements for multiple CE levels. In the example of FIG. 4, the value of “maxNumPreambleAttemptCE” IE associated with the minimum CE level (ie, CE level 1) is 20, and the value of “numRepetitionPerPreambleAttempt” IE is 4. This corresponds to the example shown in FIG. On the other hand, at higher CE levels, both the maximum number of PRACH attempts and the number of repetitive preamble transmissions per PRACH attempt increase. That is, the value of "maxNumPreambleAttemptCE" IE associated with CE level 2 is 60, and the value of "numRepetitionPerPreambleAttempt" IE is 10. Further, the value of "maxNumPreambleAttemptCE" IE associated with CE level 3 is 120, and the value of "numRepetitionPerPreambleAttempt" IE is 20.
[0034]
　In some implementations, the first radio resource configuration IE may include at least one of a plurality of IEs for the PRACH configuration listed below:
· prach-ConfigIndex; and
· prach-FreqOffset.
[0035]
　“Prach-ConfigIndex” IE indicates the value (ie, R_Slot) for defining when MTC UE1 should send a random access preamble in frequency / time grids. “Prach-FreqOffset” IE indicates the frequency offset value for identifying the Physical Resource Block (PRB) available for RACH access.
[0036]
　The 3GPP specification defines a set or one-dimensional array of a predetermined number (eg, 8) of values ​​that can be set in each radio resource setting IE. These values ​​are arranged, for example, in ascending or descending order, and each value is associated with an index value indicating the order in ascending or descending order. Therefore, each radio resource setting IE indicates an index value representing any of the values ​​contained in these sets or one-dimensional arrays. For example, in 3GPP Release 12, the RA response window size is in subframe units and can be set to eight values: 2, 3, 4, 5, 6, 7, 8, and 10 subframes. Therefore, "ra-ResponseWindowSize" IE has a 3-bit length and indicates one of these 8 values ​​with a 3-bit index value.
[0037]
　MTC UE1 receives from eNB2 the base value associated with the normal coverage (zero coverage extension, CE level 0) or the first CE level (eg, CE level 1) for the first radio resource configuration IE, and the relevant The value (second value) associated with the other CE level (second CE level (eg, CE level 2)) for the first radio resource setting IE is derived from the received base value. Therefore, the MTC UE1 does not need to receive an additional IE from the eNB2 that explicitly indicates the second value associated with the second CE level for the first radio resource configuration IE.
[0038]
　More specifically, MTC UE1 is a conversion factor for deriving a second value associated with a second CE level (eg, CE level 2) from the base value received from eNB2. Use the value. The transforming factor may be simply expressed as a factor. To support the derivation of the second value in MTC UE1, in some implementations the eNB 2 may further include the transform factor value in the system information transmitted in step 201 of FIG. Instead, in some implementations, the eNB 2 provides information that indirectly indicates the value of the transforming factor or information for deriving the value of the transforming factor in the system information transmitted in step 201 of FIG. May be further included in. For example, the information indirectly indicating the value of the conversion factor may be an index that specifies any one value from a set including a plurality of predetermined candidate values. For example, the information for deriving the value of the transforming factor may include one or more parameters substituted into a predetermined formula for calculating the transforming factor. That is, the eNB 2 may transmit information on the transforming factor (eg, the transforming factor value itself, information indirectly indicating the transforming factor value, information for deriving the transforming factor value) to MTC UE1. .. Information about the transforming factor is used by MTC UE1 to obtain the value of the transforming factor. In this case, the transforming factor and the procedure for deriving (calculating) the second value using it explicitly indicates the value associated with the second CE level for one or more radio resource configuration IEs from eNB2 to MTC UE1. The data size of the information about the transformants is defined to be smaller than the data size required to send to.
[0039]
　Prior to step 201, the eNB2 may calculate the value of the transforming factor transmitted to the MTC UE1. Specifically, eNB2 determines the value of the first radio resource setting IE for each of one or more second CE levels (eg, CE levels 1-3) and with the determined IE value. The value of the conversion factor for each second CE level may be calculated using the base value of the first radio resource setting IE (eg, IE value for CE level 0).
[0040]
　In other implementations, MTC UE1 is configured to pre-store the default value of the transform factor in memory, and if the transform factor is not explicitly transmitted from eNB2, the second from the base value of the first radio resource setting IE. The default value may be used to derive the value of.
[0041]
　FIG. 5 is a flowchart showing an example (process 500) of the operation of MTC UE1. In step 501, the MTC UE1 receives system information from the eNB2 that includes the base values ​​for the first radio resource configuration IE. As described above, the base value for the first radio resource setting IE is the value of the first radio resource setting IE associated with normal coverage (zero coverage extension) or the first CE level (eg, CE level 1). Is. The system information may further include transformants used to derive a second value associated with a second CE level for the first radio resource configuration IE from the base value.
[0042]
　In step 502, the MTC UE1 has a second CE level by converting the base value of the first radio resource configuration IE associated with normal coverage (or the first CE level) with the value of the transform factor. Derived the value of the first radio resource setting IE associated with. For example, the first radio resource configuration IE includes one or more RACH configuration IEs (eg, ra-ResponseWindowSize, and mac-ContentionResolutionTimer). In this case, MTC UE1 is associated with the first CE level (or second CE level) from the base value of one or more RACH settings IEs normally associated with coverage (or first CE level). The value of the transforming factor is used to derive the value of 2.
[0043]
　MTC UE1 measures the received power (RSRP) of the reference signal from eNB2 or the estimated propagation loss between MTC UE1 and eNB2 and determines the required CE level based on the measured RSRP or propagation loss. You may. In step 503, if the MTC UE1 requires a second CE level, the MTC UE1 is the first of the first radio resource settings IE (eg, ra-ResponseWindowSize, and mac-ContentionResolutionTimer) derived in step 502. Perform a random access procedure according to the value of 2.
[0044]
　Subsequently, some examples of the conversion factor and some examples of the procedure for deriving (calculating) the second value of the conversion factor from the basic value of the radio resource setting IE will be described. In the first example shown in FIG. 6, the transforming factor represents a multiplier factor. Further, in the first example, the value of one transform factor (multiplier) was associated with a second CE level for two or more radio resource settings IE (eg, ra-ResponseWindowSize, and mac-ContentionResolutionTimer). It is also used to derive a value of 2 or more. Therefore, in the first example, if the eNB2 transmits the value of one transform factor instead of transmitting the two or more values ​​associated with the second CE level for the two or more radio resource configuration IEs. good. Thereby, the first example can reduce the data size required for the base station to inform the radio terminal of the plurality of radio resource settings for the plurality of CE levels. The conversion factor in the first example can also be called a scaling factor, a coefficient, or a scaling coefficient.
[0045]
　More specifically, in the example of FIG. 6, MTC UE1 sets the values ​​of “ra-ResponseWindowSize” IE and “mac-ContentionResolutionTimer” IE for normal coverage (ie, zero coverage extension or CE level 0) from eNB2 to SIB. Receive (601). In FIG. 6, the RA response window size (ra-ResponseWindowSize) for normal coverage is 2 subframes (sf2), and the length of the contention resolution timer for normal coverage (mac-ContentionResolutionTimer) is 8 subframes. (Sf8).
[0046]
　MTC UE1 further receives values ​​of three transforming factors (ie, multiplier) associated with three CE levels (CE level 1, 2, 3) from eNB2 (602). In FIG. 6, the conversion factor (multiplier) values ​​for CE levels 1, 2, and 3 are 2, 3, and 4, respectively. In addition, MTC UE1 may receive only the value of the conversion factor corresponding to one required CE level out of the three CE levels from eNB2.
[0047]
　MTC UE1 usually multiplies each of two or more IE values ​​(601) for coverage by the value of the transforming factor (multiplier) (603). This allows MTC UE1 to derive two or more IE values ​​for CE levels 1, 2, or 3 (604). Note that MTC UE1 may calculate only the value corresponding to one required CE level out of the three CE levels.
[0048]
　In the second example shown in FIG. 7, the value of one transformant is used to calculate the IE value for two or more CE levels. That is, MTC UE1 not only calculates the second value of the radio resource setting IE associated with the second CE level using the base value of the radio resource setting IE and the value of the conversion factor, but also the base value. And the value of the transforming factor are used to further calculate the third value of the radio resource configuration IE associated with the third CE level. Therefore, in the second example, the eNB 2 uses the value of one transformant instead of transmitting two or more values ​​associated with the second and third CE levels for the first radio resource configuration IE. Just send it. Thereby, the second example can reduce the data size required for the base station to inform the radio terminal of the plurality of radio resource settings for the plurality of CE levels.
[0049]
　More specifically, in the example of FIG. 7, the MTC UE1 receives the value of “ra-ResponseWindowSize” IE for normal coverage (ie, zero coverage extension or CE level 0) from the eNB 2 on the SIB (701). In FIG. 7, the RA response window size (ra-ResponseWindowSize) for normal coverage is 2 subframes (sf2).
[0050]
　MTC UE1 further eNB2 sets the value of one transform factor (ie, base multiplier factor) used to determine the IE values ​​for the three CE levels (CE level 1, 2, 3). Receive from (702). In FIG. 7, the value of the conversion factor (basic multiplier) is 2.
[0051]
　MTC UE1 usually multiplies the value of the radio resource setting IE (701) for coverage by the value of the conversion factor (basic multiplier) (703). This allows MTC UE1 to derive an IE value for CE level 1 (704). Further, when obtaining the IE value for CE level 2, MTC UE1 multiplies the IE value for CE level 1 by the value of the conversion factor (basic multiplier). That is, in the example of FIG. 7, the value of the transforming factor (basic multiplier) directly or indirectly specifies the scale ratio between the IE value for normal coverage and two or more CE level IE values. This allows MTC UE1 to calculate IE values ​​for two or more CE levels based on the value of one transform factor (basic multiplier).
[0052]
　In the third example shown in FIG. 8, the transforming factor represents an offset. In the third example, similarly to the first example described above, the second for the radio resource setting IE (eg, ra-ResponseWindowSize, and mac-ContentionResolutionTimer) in which the value of one conversion factor (offset) is 2 or more. It is also used to derive two or more values ​​associated with the CE level of. Therefore, the third example can reduce the data size required for the base station to inform the radio terminal of multiple radio resource settings for multiple CE levels, similar to the first example above. can.
[0053]
　More specifically, in the example of FIG. 8, MTC UE1 sets the values ​​of “ra-ResponseWindowSize” IE and “mac-ContentionResolutionTimer” IE for normal coverage (ie, zero coverage extension or CE level 0) from eNB2 to SIB. Receive (801). In FIG. 8, the RA response window size (ra-ResponseWindowSize) for normal coverage is 2 subframes (sf2), and the length of the contention resolution timer for normal coverage (mac-ContentionResolutionTimer) is 8 subframes. (Sf8).
[0054]
　MTC UE1 further receives the values ​​of three transforming factors (ie, offset) associated with the three CE levels (CE level 1, 2, 3) from eNB2 (802). In FIG. 8, the conversion factor (offset) values ​​for CE levels 1, 2, and 3 are 2, 4, and 6, respectively. In addition, MTC UE1 may receive only the value of the conversion factor corresponding to one required CE level out of the three CE levels from eNB2.
[0055]
　MTC UE1 usually adds the value of the transforming factor (offset) to each of the two or more IE values ​​(801) for coverage (803). This allows MTC UE1 to derive two or more IE values ​​for CE levels 1, 2, or 3 (804). Note that MTC UE1 may calculate only the value corresponding to one required CE level out of the three CE levels.
[0056]
　In the fourth example shown in FIG. 9, the IE values ​​for two or more CE levels are calculated using the values ​​of one transforming factor, similar to the second example above. Therefore, the fourth example can reduce the data size required for the base station to inform the radio terminal of multiple radio resource settings for multiple CE levels, similar to the second example above. .. However, in the fourth example, the base offset is used as the transforming factor.
[0057]
　More specifically, in the example of FIG. 9, MTC UE1 sets the value of “ra-ResponseWindowSize” IE for normal coverage (ie, zero coverage extension or CE level 0) from eNB2 to SIB (eg, SIB2-bis). Receive (901). In FIG. 9, the RA response window size (ra-ResponseWindowSize) for normal coverage is 2 subframes (sf2).
[0058]
　MTC UE1 also receives from eNB2 the value of one transform factor (ie, basal offset) used to determine the IE values ​​for the three CE levels (CE levels 1, 2, 3) (902). ). In FIG. 9, the value of the conversion factor (basic offset) is 2.
[0059]
　MTC UE1 adds the value of the conversion factor (basic offset) to the value of the radio resource setting IE (901) for normal coverage (903). This allows MTC UE1 to derive an IE value for CE level 1 (904). Further, when obtaining the IE value for CE level 2, MTC UE1 adds the value of the conversion factor (basic offset) to the IE value for CE level 1. That is, in the example of FIG. 9, the conversion factor (basic offset) value indirectly specifies the scale ratio between the IE value for normal coverage and two or more CE level IE values. This allows MTC UE1 to calculate IE values ​​for two or more CE levels based on the value of one transform factor (basic offset).
[0060]
　The fifth example is a modification of the first example described above, in which the transforming factor represents a divisor factor. In the fifth example, as in the first example, the value of one transform factor (divisor) derives two or more values ​​associated with the second CE level for the two or more radio resource configuration IEs. It is also used to do. In some implementations, MTC UE1 usually divides each of the two or more IE values ​​for coverage by the value of the transforming factor (divisor) for each CE level. This allows MTC UE1 to derive two or more IE values ​​for each CE level. The fifth example may be used to determine the value of IE (eg, maxNumPreambleAttemptCE) that decreases with increasing CE level.
[0061]
　The sixth example is a modification of the second example described above, in which the transforming factor represents a base divisor factor. In the sixth example, as in the second example, the value of one transformant is used to calculate the IE value for two or more CE levels. In some implementations, MTC UE1 usually divides the IE value for coverage by the value of the transforming factor (ie, basic divisor). This allows MTC UE1 to calculate IE values ​​for two or more CE levels based on the value of one transform factor (basic divisor). The sixth example may be used to determine the value of IE (eg, maxNumPreambleAttemptCE) that decreases with increasing CE level.
[0062]
　The seventh example is a modification of the first example described above, in which the transforming factor represents an exponent of a power (power of m) of an integer m. When the conversion factor is a positive integer k, the second value of the radio resource setting IE is a value obtained by multiplying the basic value of the radio resource setting IE by the kth power of m. The value of the base m of the power may be specified in the 3GPP specifications or the like. That is, the value of the base m of the power may be stored in the memory of MTC UE1 in advance. For example, when the base m of the power is 2 and the value of the transform factor for CE level 1 is 3, the value of the radio resource setting IE for CE level 1 is for normal coverage (CE level 0). Is the value obtained by multiplying the basic value of the radio resource setting IE by 2 to the 3rd power, that is, a value eight times the basic value. In the seventh example, as in the first example, the value of one transform factor (exponent) is associated with the second CE level (eg, CE level 1) for two or more radio resource configuration IEs. It is also used to derive two or more values.
[0063]
　The above-mentioned first to seventh examples can be appropriately modified. Further, a method different from the examples of the first to sixth examples may be used to derive the second value from the basic value of the radio resource setting IE by using the conversion factor.
[0064]
　For example, in the first to seventh examples described above, the value of the conversion factor is the multiplication or addition of the specific value (eg, number of subframes) indicated by the basic value (ie, index value) of the radio resource setting IE. Or an exponent of a multiplier, offset, divisor, or power for division. Instead, the transform factor value may be an exponent of a multiplier, offset, divisor, or exponentiation for multiplying, adding, or dividing the base value itself (ie, index value) of the radio resource configuration IE. good. For example, the base value itself (ie, index value) of the radio resource setting IE may be multiplied by the value of the multiplier as a conversion factor. In this case, the specific value (eg, number of subframes) represented by the converted index value is used for each CE level.
[0065]
　The above-mentioned first to seventh examples may be used in combination as appropriate. For example, when a plurality of IE values ​​are calculated using the same conversion factor, the role of the conversion factor (ie, calculation method for deriving the IE value) may be different for each IE. For example, the value of the transforming factor may be used as a multiplier for multiplication to find the value of one IE, and the value of the transforming factor may be used as an offset for addition to find the value of another IE. ..
[0066]
　In some implementations, the value of the transforming factor for determining the value associated with the second CE level for the first radio resource configuration IE is different from the first radio resource configuration IE for the second radio. It may also be used as the value associated with the second coverage improvement level for the resource setting IE. For example, MTC UE1 has a value of “numRepetitionPerPreambleAttempt” IE indicating the number of preamble repetitions (PRACH preamble repetition level) received from eNB2 and the number of RA response repetitions (RAR repetition) at the second CE level. A conversion factor for determining the value associated with the second CE level for "ra-ResponseWindowSize" IE and "mac-ContentionResolutionTimer" IE, either or both of the values ​​of "numRepetitionPerRA-Response" IE indicating level). May be used as. Further or instead, MTC UE1 indicates the IE value indicating the repetition level (number of repetitions) of the third message (RRC Connection Request message) of the random access procedure at the second CE level received from eNB2 and the fourth. Either or both of the IE values ​​that indicate the repetition level of the message (Contention Resolution message) can be used as a transformant to determine the value associated with the second CE level for the "mac-ContentionResolutionTimer" IE. You may use it. In these two examples, PRACH preamble repetition level and RAR repetition
[0067]
　In some implementations, other values ​​may be used in addition to the transformants to determine the IE value corresponding to the required CE level in MTC UE1. For example, the IE value may be derived using the repetition level and conversion factor of the corresponding signal (preamble, message). For example, the value of ra-ResponseWindowSize for the first CE level (eg, CE level 0) is set to the value of PRACH preamble repetition level for the second CE level (eg, CE level 1, 2, or 3). The value of ra-ResponseWindowSize for the second CE level may be derived by multiplying and then multiplying (or adding or dividing) the value of the transforming factor. At this time, the value of the conversion factor may be the value of the interval of the repeated transmission of the RACH preamble or the value of the interval of the repeated transmission of the RAR message (M-PDCCH or PDSCH).
[0068]
　Further, when the same conversion factor is applied to a plurality of IEs, the IE value may be derived using the repetition level (number of repetitions) of the corresponding signal (preamble, message) and the same conversion factor. For example, the value of ra-ResponseWindowSize for the first CE level (eg, CE level 0) and the value of PRACH preamble repetition level for the second CE level (eg, CE level 1, 2, or 3) or The value of ra-ResponseWindowSize for the second CE level may be derived by multiplying the value of RAR repetition level and then multiplying (or adding or dividing) the value of the transforming factor. Similarly, the value of mac-ContentioResolutionTimer for the first CE level (eg, CE level 0) and the third message (RRC Connection) for the second CE level (eg, CE level 1, 2, or 3). By multiplying either or both of the repetition level value of the Request message) and the repetition level value of the fourth message (Contention Resolution message), and then multiplying (or adding or dividing) the same conversion factor. You may derive the value of mac-ContentioResolutionTimer for CE level of 2.
[0069]
　In some implementations, the transform factor value may be a CE level value. For example, the value of the conversion factor may be a value (eg, 1) indicating the required CE level (eg, CE level 1) or a value obtained by converting the value according to a predetermined conversion formula.
[0070]
　In some implementations, IE values ​​are derived using transformants only for some CE levels (eg, CE level 1) of multiple CE levels, and the remaining CE levels (eg, CE level 1). The IE value for and CE level 2) may be derived from the IE value for the part of the CE level (eg, CE level 1) according to a predetermined rule. For example, the IE value for CE level 2 is twice the IE value for CE level 1, and the IE value for CE level 3 is three times the IE value for CE level 1. May be done. Instead, the IE value for CE level 2 is the IE value for CE level 1 plus "offset +2", and the IE value for CE level 3 is the IE value for CE level 1. It may be a value obtained by adding "offset + 3" to the value. Alternatively, the IE value may be derived using a value corresponding to the difference (eg, ratio, difference) in the repetition level (number of repetitions) between CE levels. For example, if CE level 1 has a repetition level of 2 and CE level 2 has a repetition level of 4, the IE value of CE level 2 is 4/2 times the value of CE level 1, that is, twice the value. May be good.
[0071]
　In the first, third, fifth, and seventh examples described above, an example is shown in which the value of one conversion factor is set (or used) for each of two or more radio resource setting IEs. In the second, fourth, and sixth examples, examples are shown in which the value of one transforming factor is set (or used) for each of two or more CE levels. Instead of these, in some implementations, the value of one transform factor may be set (or used) per radio resource setting IE and per CE level. In this case, the conversion factor is preferably defined so that the bit length of IE indicating the conversion factor is smaller than the bit length of the radio resource setting IE.
[0072]
　FIG. 10 is a diagram showing an example (process 1000) of the random access procedure according to the present embodiment. In step 1001, the MTC UE1 determines the required CE level based on the measured quality of signal reception from eNB2 (eg, RSRP) or the measured propagation loss between UE1 and eNB2 (estimated value). Determine (estimate).
[0073]
　In step 1002, the MTC UE1 receives the system information (SIB) transmitted from the eNB2 while applying the coverage improvement technology (eg, repeated transmission of system information (SIB)) corresponding to the determined CE level. The system information includes the normal coverage for the first radio resource configuration IE (eg, one or more RACH configuration IEs) or the underlying values ​​associated with the first CE level (eg, CE level 1). , Further includes information on transforming factors for deriving the values ​​of the first radio resource configuration IE associated with the second CE level (eg, CE level 2). As described above, the information about the transforming factor may include, for example, the transforming factor value itself, or information that indirectly indicates the transforming factor value or information for deriving the transforming factor value. May be good.
[0074]
　In step 1003, the MTC UE1 transforms the base value of the first radio resource configuration IE associated with normal coverage (or first CE level) using the value of the transform factor. The value of the transforming factor can be obtained from the information about the transforming factor received from eNB2. Thereby, MTC UE1 derives the value of the first radio resource setting IE associated with the determined required CE level.
[0075]
　After that, the MTC UE1 performs a random access procedure according to the derived value of the first radio resource setting IE (eg, one or a plurality of RACH setting IEs) (steps 1004 to 1006).
[0076]
　In step 1004, if MTC UE1 does not succeed in random access even after reaching the maximum number of attempts of the RACH preamble for the determined (estimated) CE level (eg, CE level 1), the next CE level (eg, CE level 2) ) May be used to initiate the transmission of the RACH preamble. At this time, MTC UE1 derives the settings corresponding to the next CE level (eg, CE level 2), for example, the values ​​of "ra-ResponseWindowSize" IE and "mac-ContentionResolutionTimer" IE when the CE level is changed. Alternatively, the values ​​corresponding to a plurality of CE levels may be derived collectively in advance.
[0077]
　Note that the MTC UE1 may start measuring the RA response window according to the “ra-ResponseWindowSize” IE from the beginning or the last three subframes of the repeated transmission within one trial of the RACH preamble transmission in step 1004. The “ra-ResponseWindowSize” IE indicates the time that the MTC UE1 should wait for the random access response (RAR) of step 1006 to be received after transmitting the RACH preamble of step 1004. In addition, the MTC UE1 may start measuring the MAC contention resolution timer according to the "mac-ContentionResolutionTimer" IE from either the beginning or the end of the repeated transmission of the third message (Msg3) of the random access procedure. “Mac-ContentionResolutionTimer” IE indicates the time that MTC UE1 should wait for the reception (and content confirmation) of the Contention Resolution message after sending the third message (Msg3).
[0078]
　In step 1005, the eNB 2 detects a random access (RA) preamble (RACH preamble) transmitted from the MTC UE1. For example, eNB2 determines the CE level of MTC UE1 based on the radio resource in which the RA preamble was detected. Then, the eNB2 repeatedly receives the RA preamble and repeatedly transmits the RA response according to the values ​​of a plurality of IEs (eg, “numRepetitionPerPreambleAttempt” IE, “ra-ResponseWindowSize” IE) corresponding to the determined CE level of the MTC UE1. Perform actions to improve coverage, including. In some implementations, eNB2 may calculate multiple IE values ​​corresponding to the CE level of the MTC UE1 based on the value of the transformant for the determined CE level of the MTC UE1. In some other implementations, eNB2 corresponds to the CE level of MTC UE1 determined by referring to a lookup table that stores multiple IE values ​​corresponding to each CE level. You may calculate the value of IE.
[0079]
　In the above specific example, the method of deriving the value corresponding to each CE level for the existing radio parameter (IE of RRC message) in the random access procedure has been described. Similarly, the above derivation method may be used to derive a value corresponding to each CE level for a radio parameter (IE of RRC message) newly defined for coverage improvement technology. .. For example, the above derivation method may be applied to IE (ie, maxNumPreambleAttemptCE), which indicates the maximum number of RACH preamble attempts per CE level, and IE (ie, numRepetitionPerPreambleAttempt), which indicates the maximum number of iterations per RACH preamble attempt. good. In this case, eNB2 sends the IE value corresponding to the lowest CE level (eg, CE level 1) in the system information, and UE1 goes to one or more higher CE levels (eg, CE level 2 or higher). The corresponding IE value may be derived using the transformants described above.
[0080]
　The above random access procedure may be applied not only to the initial access when the UE changes from the RRC_IDLE state to the RRC_CONNECTED state, but also to the random access in the RRC_CONNECTED state. Furthermore, in the case of random access by an execution instruction (PDCCH Order) from eNB2, the execution instruction may include at least one of the basic value and the conversion factor.
[0081]
　Subsequently, a configuration example of MTC UE1 and eNB2 according to the present embodiment will be described below. FIG. 11 is a block diagram showing a configuration example of MTC UE1. Radio Frequency (RF) transceiver 1101 performs analog RF signal processing to communicate with eNB2. The analog RF signal processing performed by the RF transceiver 1101 includes frequency up-conversion, frequency down-conversion, and amplification. The RF transceiver 1101 is coupled with the antenna 1102 and the baseband processor 1103. That is, the RF transceiver 1101 receives the modulation symbol data (or OFDM symbol data) from the baseband processor 1103, generates a transmission RF signal, and supplies the transmission RF signal to the antenna 1102. Further, the RF transceiver 1101 generates a baseband reception signal based on the reception RF signal received by the antenna 1102, and supplies the baseband reception signal to the baseband processor 1103.
[0082]
　The baseband processor 1103 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. Digital baseband signal processing includes (a) data compression / restoration, (b) data segmentation / concatenation, (c) transmission format (transmission frame) generation / decomposition, and (d) transmission path coding / decoding. , (E) Modulation (symbol mapping) / demodulation, and (f) Generation of OFDM symbol data (baseband OFDM signal) by Inverse Fast Fourier Transform (IFFT). On the other hand, control plane processing includes layer 1 (eg, transmission power control), layer 2 (eg, radio resource management, and hybrid automatic repeat request (HARQ) processing), and layer 3 (eg, attach, mobility, and packet communication). Includes communication management of).
[0083]
　For example, for LTE and LTE-Advanced, digital baseband signal processing by the baseband processor 1103 includes signal processing at the Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, MAC layer, and PHY layer. It may be. Further, the control plane processing by the baseband processor 1103 may include the processing of the Non-Access Stratum (NAS) protocol, the RRC protocol, and the MAC CE.
[0084]
　The baseband processor 1103 includes a modem processor (eg, Digital Signal Processor (DSP)) that performs digital baseband signal processing, a protocol stack processor (eg, Central Processing Unit (CPU)) that performs control plane processing, or a Micro Processing Unit. (MPU)) may be included. In this case, the protocol stack processor that performs the control plane processing may be shared with the application processor 1104 described later.
[0085]
　The application processor 1104 is also referred to as a CPU, MPU, microprocessor, or processor core. The application processor 1104 may include a plurality of processors (a plurality of processor cores). The application processor 1104 executes a system software program (Operating System (OS)) read from memory 1106 or a memory (not shown) and various application programs (eg, communication applications that acquire metering data or sensing data). By doing so, various functions of MTC UE1 are realized.
[0086]
　In some implementations, the baseband processor 1103 and the application processor 1104 may be integrated on one chip, as shown by the dashed line (1105) in FIG. In other words, the baseband processor 1103 and the application processor 1104 may be implemented as one System on Chip (SoC) device 1105. SoC devices are sometimes referred to as system large scale integration (LSI) or chipsets.
[0087]
　The memory 1106 is a volatile memory, a non-volatile memory, or a combination thereof. The memory 1106 may include a plurality of physically independent memory devices. Volatile memory is, for example, Static Random Access Memory (SRAM) or Dynamic RAM (DRAM), or a combination thereof. Non-volatile memory can be masked Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or hard disk drive, or any combination thereof. For example, memory 1106 may include external memory devices accessible from baseband processor 1103, application processor 1104, and SoC 1105. The memory 1106 may include a built-in memory device integrated in the baseband processor 1103, the application processor 1104, or the SoC 1105. Further, the memory 1106 may include the memory in the Universal Integrated Circuit Card (UICC).
[0088]
　The memory 1106 may store one or more software modules (computer programs) 1107 that include instructions and data for performing processing by the MTC UE 1 described in the plurality of embodiments described above. In some implementations, the baseband processor 1103 or application processor 1104 may be configured to perform the processing of the MTC UE1 described in the embodiments described above by reading the software module 1107 from memory 1106 and executing it. good.
[0089]
　FIG. 12 is a block diagram showing a configuration example of the base station (eNB) 2 according to the above-described embodiment. With reference to FIG. 12, eNB2 includes RF transceiver 1201, network interface 1203, processor 1204, and memory 1205. The RF transceiver 1201 performs analog RF signal processing in order to communicate with the wireless terminal 1. RF transceiver 1201 may include a plurality of transceivers. RF transceiver 1201 is coupled with antenna 1202 and processor 1204. The RF transceiver 1201 receives modulation symbol data (or OFDM symbol data) from processor 1204, generates a transmit RF signal, and supplies the transmit RF signal to the antenna 1202. Further, the RF transceiver 1201 generates a baseband reception signal based on the reception RF signal received by the antenna 1202, and supplies the baseband reception signal to the processor 1204.
[0090]
　Network interface 1203 is used to communicate with network nodes (eg, Mobility Management Entity (MME) and Serving Gateway (S-GW)). The network interface 1203 may include, for example, an IEEE 802.3 series compliant network interface card (NIC).
[0091]
　Processor 1204 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. For example, in the case of LTE and LTE-Advanced, the digital baseband signal processing by processor 1204 may include signal processing of the PDCP layer, RLC layer, MAC layer, and PHY layer. Further, the control plane processing by the processor 1204 may include the processing of the S1 protocol, the RRC protocol, and the MAC CE.
[0092]
　Processor 1204 may include a plurality of processors. For example, processor 1204 may include a modem processor (eg, DSP) for digital baseband signal processing and a protocol stack processor (eg, CPU or MPU) for control plane processing.
[0093]
　The memory 1205 is composed of a combination of a volatile memory and a non-volatile memory. Volatile memory is, for example, SRAM or DRAM or a combination thereof. The non-volatile memory is, for example, an MROM, a PROM, a flash memory, a hard disk drive, or a combination thereof. Memory 1205 may include storage located away from processor 1204. In this case, processor 1204 may access memory 1205 via network interface 1203 or an I / O interface (not shown).
[0094]
　The memory 1205 may store a software module (computer program) 1206 including instructions and data for performing processing by the eNB2 described in the plurality of embodiments described above. In some implementations, processor 1204 may be configured to perform the processing of eNB2 described in the embodiments described above by reading the software module 1206 from memory 1205 and executing it.
[0095]
　As described with reference to FIGS. 11 and 12, each of the processors included in the MTC UE1 and eNB2 according to the above-described embodiment includes a group of instructions for causing the computer to perform the algorithm described with reference to the drawings. Or execute multiple programs. This program can be stored and supplied to a computer using various types of non-transitory computer readable medium. Non-transient computer-readable media include various types of tangible storage media. Examples of non-temporary computer-readable media include magnetic recording media (eg flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (eg magneto-optical disks), Compact Disc Read Only Memory (CD-ROM), CD- Includes R, CD-R / W, semiconductor memory (eg, mask ROM, Programmable ROM (PROM), Erasable PROM (EPROM), flash ROM, Random Access Memory (RAM)). The program may also be supplied to the computer by various types of transient computer readable medium. Examples of temporary computer-readable media include electrical, optical, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.
[0096]
The
　above-described embodiment has mainly described the radio resource setting IE (eg, RACH setting IE and PRACH setting IE) related to random access. However, the technique of deriving IE values ​​for a particular CE level using the transformants described in the embodiments above is when different radio resource settings are required depending on the coverage improvement (CE) level. It can be widely used. The method described in the above embodiment is, for example, that the MTC UE1 in the RRC_CONNECTED state transmits UL user data in PUSCH, transmits L1 / L2 control information in PUCCH, receives system information or DL ​​user data in PDSCH, and so on. And may be used to derive the value of the radio resource setting IE (eg, number of transmission (reception) repetitions) required when receiving L1 / L2 control information on the M-PDCCH at a specific CE level. ..
[0097]
　The above-described embodiment has mainly described the case where eNB2 transmits information about a transforming factor as system information. However, the information about the transforming factor may be transmitted by a signal (eg, RRC signaling, MAC signaling) in which the eNB 2 transmits individual control information to the MTC UE 1. For example, information about the transforming factor may be sent from eNB2 to MTC UE1 in an RRC Connection Reconfiguration message or MAC Control Element. When MTC UE1 receives the information about the conversion factor in the system information and the individual control information, the value of the conversion factor obtained from the information about the conversion factor notified in the individual control information is given priority (that is, the system information). The value of the transforming factor obtained from is overwritten with the value of the transforming factor obtained from the individual control information).
[0098]
　The behavior of MTC UE1 and eNB2 regarding the derivation of IE values ​​using the transformants described in the above embodiments is to derive timer values ​​that require different lengths depending on the coverage improvement (CE) level. It may be used for. Specific examples of timers that use different timer values ​​for multiple CE levels include (1) timers related to control (ie, RRC, NAS) such as call processing, and (2) Layer 2 (ie, PDCP, RLC). , MAC) Includes timers related to control, and (3) timers that measure in the RRC_IDLE state.
[0099]
　For example, the timer (1) described above may be a timer (ie, timer T300) used to determine success or failure of RRC connection establishment. MTC UE1 starts the timer (ie, timer T300) from the time when the RRC Connection Reestablishment Request message is sent, and when the response from eNB2 (ie, RRC Connection Setup message or RRC Connection Reject message) is received, the timer is concerned. To stop.
[0100]
　Further or instead, the timer (1) described above may be a timer (ie, timer T311) for determining success or failure of detection of a suitable cell. The MTC UE1 starts the timer (ie, timer T311) from the time when the RRC Connection Reestablishment procedure is started, and stops the timer when a suitable cell is detected (selected).
[0101]
　Further or instead, the timer (1) described above may be a timer (ie, timer T304) for determining the success or failure of the handover. When MTC UE1 starts the timer (ie, timer T304) from the time when it receives the RRC Connection Reconfiguration message containing MobilityControlInfo IE (that is, it becomes a handover instruction) and successfully completes the random access procedure to the target cell. To stop the timer.
[0102]
　For example, the timer (2) described above may be a timer used to control the MAC layer. Specific examples of timers used to control the MAC layer include timers (eg, OnDurationTimer, drx-InactivityTimer, drx-RetransmissionTimer, HART RTT Timer) related to intermittent reception control (DRX) in the UE, and scheduling requests. A timer (eg, sr-ProhibitTimer, logicalChannelSR-ProhibitTimer) that measures the period during which (Scheduling Request (SR)) is prohibited, and a timer (eg, PeriodicBSR) related to the uplink buffer amount report (Buffer Status Report (BSR)). -Includes timers (eg, periodicPHR-Timer, prohibitPHR-Timer) related to (Timer, RetxBSR-Timer), and a report of the remaining amount of uplink transmit power (Power Headroom Report (PHR)).
[0103]
　Further or instead, the timer (2) described above may be a timer used for controlling the RLC layer. Specific examples of the timer used to control the RLC layer include the timer (T-Reordering) used to detect the loss of RLC PDU and control the order in DL data reception, and the information indicating the DL data reception status (STATUS). Includes a timer (T-StatusProhibit) that measures the period during which transmission of PDU) is prohibited.
[0104]
　Further or instead, the timer (2) described above may be a timer used for controlling the PDCP layer. Specific examples of timers used to control the PDCP layer include a timer (discardTimer) that determines whether to discard untransmitted data in UL data transmission.
[0105]
　For example, the timer (3) described above may be a timer used in the cell reselection process by MTC UE1 in the RRC_IDLE state. Specifically, the timer (3) described above may be a timer for measuring the duration (ie, T-Reselection) in which the conditional expression for triggering cell reselection is satisfied.
[0106]
　The timer measurement described above may be started at either the beginning or the end of repeated transmissions of associated (ie, triggering) signals (messages). Alternatively, timer measurement may start at either the beginning or the end of repeated reception of the associated signals (messages).
[0107]
　In the above-described embodiment, the wireless terminal 1 may be a non-MTC UE. That is, the above-described embodiment can be widely applied to communication between a UE and an eNB that supports coverage improvement techniques including repeated transmission (or reception).
[0108]
　Furthermore, the above embodiments are not limited to LTE, LTE-Advanced and improvements thereof, and are applicable to communication between wireless terminals and base stations that support coverage improvement techniques in other wireless communication networks or systems. May be done.
[0109]
　For example, the above-described embodiment may be applied to a coverage improvement technique in a system called Narrow Band-Internet of Things (NB-IoT), which is being studied in 3GPP. NB-IoT aims to accommodate low-cost and ultra-low power consumption IoT terminals (for example, operating for 10 years without battery replacement) in a cellular network. NB-IoT is very similar to Rel-13 MTC in terms of purpose and target device characteristics, and it is considered to reuse the technology of 3GPP Release 13 (Rel-13) MTC for NB-IoT. ing. Therefore, the above embodiments may be applied to NB-IoT. In addition, Rel-13 MTC UE sends RACH preamble in random access, but in NB-IoT, it is considered that UE sends a message (eg, contention-based message) instead of preamble in PRACH. In this way, it is also considered to improve Rel-13 MTC for NB-IoT or introduce functions that Rel-13 MTC does not have into NB-IoT, but the above-described embodiment is not related to the difference. It can be applied to NB-IoT.
[0110]
　Furthermore, the above-described embodiment is merely an example relating to the application of the technical idea obtained by the inventor of the present invention. That is, the technical idea is not limited to the above-described embodiment, and it goes without saying that various changes can be made.
[0111]
　For example, some or all of the above embodiments may also be described, but not limited to:
[0112]
(Supplementary Note A1)
　a base station,
　a memory,
　and at least one processor coupled to said memory,
comprising a
　at least one processor is usually coverage or first for the first radio resource configuration information element The first value associated with the coverage improvement level of the
　above and the information about the conversion factor are configured to be transmitted to the wireless terminal, and the value of the conversion factor obtained from the information about the conversion factor is the value of the first radio. A
base station used by the radio terminal to derive a second value associated with a second coverage improvement level for a resource configuration information element from the first value .
[0113]
(Appendix A2)
　The first radio resource setting information element includes two or more radio resource setting information elements, and
　the second value is the second coverage improvement for the two or more radio resource setting information elements. The value of the
　transforming factor, including two or more values ​​associated with the level,
is described in Appendix A1, commonly used by the radio terminal to derive the two or more values ​​from the first value. Base station.
[0114]
(Appendix A3) In
　addition to the second value, the value of the conversion factor is the first value associated with the third coverage improvement level for the first radio resource setting information element.
The base station according to Appendix A1, which is used by the wireless terminal to derive from the value .
[0115]
(Appendix A4) The base according to Appendix A3
　, wherein the value of the transforming factor directly or indirectly specifies a scale ratio between the first value, the second value, and the third value.
Station.
[0116]
(Appendix A5)
　The value of the conversion factor includes a multiplier value, and
　the second value is calculated by multiplying the first value by the multiplier value,
in any one of the appendices A1 to A4. The listed base station.
[0117]
(Appendix A6)
　The value of the conversion factor includes an offset value, and
　the second value is calculated by adding the offset value to the first value,
in any one of the items A1 to A4. The listed base station.
[0118]
(Appendix A7)
　The value of the conversion factor is also used as a value associated with the second coverage improvement level for the second radio resource setting information element different from the first radio resource setting information element.
The base station according to any one of Supplementary A1 to A4.
[0119]
(Appendix A8)
　The first radio resource configuration information element includes at least one parameter related to a random access procedure, and the
　at least one parameter is
(a) a frequency and a frequency that can be used for transmission of a random access preamble. Parameters that define the time resource, (b) Parameters that indicate the total number of random access preambles, (c) Parameters that indicate the maximum number of random access preamble transmission attempts (attempts), (d) Random access preamble transmission attempts. The number of repetitions of random access preamble transmission per hit, (e) a parameter indicating the duration (duration) of the random access response window, (f) a parameter indicating the duration (duration) of the contention resolution timer. , (G) the maximum number of repetitions of the random access response transmission by the base station, and (h) a parameter indicating the maximum number of retransmissions of the third message in response to the reception of the random access response.
The base station according to any one of Supplementary A1 to A7.
[0120]
(Appendix A9) The
　at least one processor further calculates the value of the conversion factor to be transmitted to the wireless terminal using the first value and the second value, and the calculated conversion.
The base station according to any one of Supplementary A1 to A8 , which is configured to transmit the value of the factor to the wireless terminal .
[0121]
(Supplementary Note B1)
　a wireless terminal,
　a memory,
　and at least one processor coupled to said memory,
comprising a
　at least one processor is configured to perform at least one module,
　said at least one module is
　a normal first value associated with a coverage or first coverage improvement level for the first radio resource configuration information element, a receiving module configured to receive from the base station,
　using the value of the conversion factor by converting the first value Te, a calculation module configured to derive a second value associated with a second coverage improvement level for the first radio resource configuration information element
comprises ,
Wireless terminal.
[0122]
(Appendix B2)
　The first radio resource setting information element includes two or more radio resource setting information elements, and
　the second value is the second coverage improvement for the two or more radio resource setting information elements. The addition B1 which comprises two or more values ​​associated with a level,
　wherein the calculation module commonly uses the value of the transforming factor to derive the two or more values ​​from the first value
. Wireless terminal.
[0123]
(Appendix B3) In
　addition to the second value, the calculation module obtains a third value associated with the third coverage improvement level for the first radio resource setting information element from the first value.
The wireless terminal according to Appendix B1 , wherein the value of the conversion factor is commonly used for derivation .
[0124]
(Supplementary Note B4)
　value of the conversion factor, the first value, the second value, and specifying either directly or indirectly the scale ratio between the third value,
the radio of statement B3 Terminal.
[0125]
(Supplementary note B5) The item according to any one of Supplementary note B1 to B4,
　wherein the at least one processor is configured to receive information about the conversion factor for obtaining the value of the conversion factor from the base station
. Wireless terminal.
[0126]
(Supplementary Note B6)
　value of the conversion factor comprises a multiplier value,
　the second value, said computed by multiplying the multiplier value to the first value,
in any one of Appendices B1 ~ B5 Described wireless terminal.
[0127]
(Appendix B7)
　The value of the conversion factor includes an offset value, and
　the second value is calculated by adding the offset value to the first value,
in any one of the items B1 to B5. Described wireless terminal.
[0128]
(Appendix B8)
　The value of the conversion factor is also used as a value associated with the second coverage improvement level for the second radio resource setting information element different from the first radio resource setting information element.
The wireless terminal according to Appendix B5.
[0129]
(Appendix B9) The
　at least one module further includes
　an estimation module configured to estimate the coverage improvement level to be followed by the radio terminal and
　the first radio resource associated with the estimated coverage improvement level. a communication module for communicating with the base station according to the value of the setting information element
comprises a,
　the calculation module, wherein as the value of the estimated coverage improved to the first associated level radio resource configuration information element first
The wireless terminal according to any one of Appendix B1 to B8 , which calculates the value of 2 .
[0130]
(Appendix B10)
　The first radio resource configuration information element includes at least one parameter related to a random access procedure, and the
　at least one parameter is
(a) a frequency and a frequency that can be used for transmission of a random access preamble. Parameters that define the time resource, (b) Parameters that indicate the total number of random access preambles, (c) Parameters that indicate the maximum number of random access preamble transmission attempts (attempts), (d) Random access preamble transmission attempts. The number of repetitions of random access preamble transmission per hit, (e) a parameter indicating the duration (duration) of the random access response window, (f) a parameter indicating the duration (duration) of the contention resolution timer. , (G) the maximum number of repetitions of the random access response transmission by the base station, and (h) a parameter indicating the maximum number of retransmissions of the third message in response to the reception of the random access response.
The wireless terminal according to any one of Supplementary Provisions B1 to B9.
[0131]
　This application claims priority on the basis of Japanese application Japanese Patent Application No. 2015-217963 filed on November 5, 2015, and incorporates all of its disclosures herein.
Code description
[0132]
1 Radio terminal (UE)
2 Base station (eNB)
1101 radio frequency (RF) Transceiver
1103 Baseband processor
1104 Application processor
1106 Memory
1201 RF Transceiver
1204 Processor
1205 Memory
The scope of the claims
[Claim 1]
　A base station,
　a memory and,
　at least one processor coupled to the memory,
provided with,
　at least one processor is usually coverage or first coverage improvement level for the first radio resource configuration information element The first value associated with is and the information about the conversion factor is configured to be transmitted to the wireless terminal, and the value of the conversion factor
　obtained from the information about the conversion factor is the first radio resource setting information element. A
base station used by the radio terminal to derive a second value associated with a second coverage improvement level for the first value .
[Claim 2]
　The first radio resource setting information element includes two or more radio resource setting information elements, and
　the second value is associated with the second coverage improvement level for the two or more radio resource setting information elements. The base station according to claim 1
　, wherein the value of the conversion factor includes two or more values, and is commonly used by the wireless terminal to derive the two or more values ​​from the first value.
..
[Claim 3]
　In addition to the second value, the value of the conversion factor derives a third value associated with the third coverage improvement level for the first radio resource setting information element from the first value.
The base station according to claim 1, which is used by the wireless terminal for the purpose .
[Claim 4]
　The value of the conversion factor, wherein the first radio resource configuration information element is also used as the value associated with the second coverage improvement levels for different second radio resource configuration information element,
according to claim 1 The base station according to any one of 3.
[Claim 5]
　The at least one processor further calculates the value of the transforming factor to be transmitted to the wireless terminal using the first value and the second value, and obtains the calculated value of the transforming factor.
The base station according to any one of claims 1 to 4 , which is configured to transmit to the wireless terminal .
[Claim 6]
　A method in a base station, in which a
　first value associated with a normal coverage or first coverage improvement level for a first radio resource configuration information element and information about a conversion factor are transmitted to a radio terminal. the provided,
　the value of the conversion factor obtained from the information on the conversion factor, from the second of the second of said values first value associated with a coverage improvement level for the first radio resource configuration information element The
method used by said radio terminal to derive .
[Claim 7]
　A non-transitory computer-readable medium containing a program for causing a computer to perform a method at a base station,
　wherein the method has a normal coverage or a first coverage improvement level for a first radio resource configuration information element. The associated first value and information about the transforming factor are transmitted to the wireless terminal, and the value of the transforming factor
　obtained from the information about the transforming factor is about the first radio resource setting information element. A
non-transitory computer-readable medium used by the wireless terminal to derive a second value associated with a second coverage enhancement level of the first value .
[Claim 8]
　A wireless terminal,
　a memory,
　and at least one processor coupled to said memory,
comprising a
　at least one processor is configured to perform at least one module,
　said at least one module,
　the first Usually coverage or a first value associated with a first coverage improvement level, a receiving module configured to receive from a base station, for the radio resource configuration information element
　of the first using the value of the conversion factor by converting the values, a calculation module configured to derive a second value associated with a second coverage improvement level for the first radio resource configuration information element
comprises,
wireless terminal.
[Claim 9]
　The first radio resource setting information element includes two or more radio resource setting information elements, and
　the second value is associated with the second coverage improvement level for the two or more radio resource setting information elements. The wireless terminal according to claim 8 ,
　wherein the calculation module commonly uses the value of the conversion factor in order to derive the value of 2 or more from the first value
.
[Claim 10]
　In addition to the second value, the calculation module derives a third value associated with a third coverage improvement level for the first radio resource configuration information element from the first value.
The wireless terminal according to claim 8, wherein the value of the conversion factor is commonly used .
[Claim 11]

The wireless terminal according to any one of claims 8 to 10, 　wherein the at least one processor is configured to receive information about the conversion factor for obtaining the value of the conversion factor from the base station .
[Claim 12]
　11. The value of the conversion factor is also used as a value associated with the second coverage improvement level for the second radio resource setting information element different from the first radio resource setting information element, according to
claim 11. Described wireless terminal.
[Claim 13]
　The at least one module further
　comprises an estimation module configured to estimate the coverage improvement level to be followed by the radio terminal and
　the first radio resource configuration information element associated with the estimated coverage improvement level. The 　calculation module comprises a communication module that communicates with the base station according to a value,
and the
calculation module sets the second value as the value of the first radio resource setting information element associated with the estimated coverage improvement level.
The wireless terminal according to any one of claims 8 to 12, which is calculated .
[Claim 14]
　The first radio resource configuration information element comprises at least one parameter for random access procedure,
　wherein the at least one parameter
defining the available frequency and time resources for the transmission of (a) a random access preamble Parameters to be used, (b) Parameters indicating the total number of random access preambles, (c) Parameters indicating the maximum number of random access preamble transmission attempts (attempts), (d) Random access per random access preamble transmission attempt -Number of repetitions of preamble transmission, (e) Parameter indicating the duration (duration) of the random access response window, (f) Parameter indicating the duration (duration) of the contention resolution timer, (g) 8. To
claim 8 , which includes at least one of a maximum number of repetitions of the random access response transmission by the base station and (h) a parameter indicating the maximum number of retransmissions of the third message in response to the reception of the random access response. 13. The wireless terminal according to any one of 13.
[Claim 15]
　A method in a radio terminal, in which a
　first value associated with a normal coverage or a first coverage improvement level for a first radio resource configuration information element is received from a base station, and a
　conversion factor value is used. A method comprising transforming the first value in use to derive a second value associated with a second coverage improvement level for the first radio resource configuration information element
.
[Claim 16]
　A non-transitory computer-readable medium containing a program for causing a computer to perform a method on a wireless terminal,
　wherein the method has
　a normal coverage or a first coverage improvement level for a first radio resource configuration information element. A
　second coverage of the first radio resource configuration information element by receiving the associated first value from the base station and converting the first value using the value of the transforming factor. A
non-transitory computer-readable medium , comprising deriving a second value associated with an improvement level .