Base station, method in base station and wireless terminal

Abstract

The present invention provides a base station, a method in the base station and a wireless terminal. The base station includes: a memory; and at least one processor connected to the memory, the at least one processor is configured to send a first value of a first wireless resource configuration information element and information related to a conversion factor to a wireless terminal, the first value is associated with normal coverage or a first coverage enhancement level, the wireless terminal uses the value of the conversion factor obtained from the information related to the conversion factor to derive a second value of the first wireless resource configuration information element from the first value, the second value is associated with a second coverage enhancement level, the value of the conversion factor is also used to derive a value of a second wireless resource configuration information element, the value of the second wireless resource configuration information element is associated with the second coverage enhancement level, the first wireless resource configuration information element includes at least one parameter related to a random access process, and the second wireless resource configuration information element is the number of repetitions of a message of the random access process.

Description

[0001] This application is a divisional application of the Chinese invention patent application with application date of September 13, 2016, application number 201680057281.1, and invention name “Base station, wireless terminal and method thereof”. Technical Field

[0002] The present invention relates to a wireless communication system configured to perform communication control for coverage enhancement. Background Art

[0003] In the 3rd Generation Partnership Project (3GPP), standardization of technologies for improving the degradation of communication quality caused by the sharp increase in mobile services in recent years and for achieving faster communication has been carried out. In addition, standardization of technologies for avoiding the increase in control signaling load caused by the connection of a large number of machine-to-machine (M2M) terminals to a long-term evolution (LTE) or advanced LTE network has been carried out. M2M terminals are, for example, terminals that communicate without human intervention. M2M terminals are placed in various types of equipment including machines (e.g., vending machines, gas meters, electric meters, vehicles, rail vehicles, and ships, etc.) and sensors (e.g., environmental sensors, agricultural sensors, and traffic sensors, etc.). In LTE and advanced LTE, the communication performed by the M2M terminal is called machine type communication (MTC), and the terminal performing MTC is called an MTC terminal (i.e., an MTC user equipment (MTC UE)).

[0004] Although M2M service providers need to deploy a large number of M2M terminals, the allowable cost of each M2M terminal is limited. Therefore, for example, the M2M terminal is required to be implemented at a low cost and the M2M terminal can communicate with low power consumption. In addition, in one use case, the MTC UE communicates when it is fixedly or statically installed in a building. In this case, the wireless quality of the MTC UE may always be lower than that of normal UEs with mobility (e.g., mobile phones, smart phones, tablet computers, and notebook personal computers (notebook PCs)), so the MTC UE particularly needs coverage enhancement technology. In addition, functional limitations that contribute to cost reduction include, for example, low maximum transmit power, a small number of receive antennas (e.g., only one receive antenna), no support for high-order modulation schemes (e.g., 64 quadrature amplitude modulation (64QAM)), and a narrow operating bandwidth (e.g., 1.4MHz), which reduce the maximum transmission rate of the MTC UE.

[0005] Therefore, in 3GPP, standardization of technologies for improving or enhancing the communication characteristics (i.e., coverage) of MTC UEs that are lower than those of normal UEs has been carried out (Non-Patent Document 1). The following description provides some examples of technologies for enhancing the coverage of MTC UEs discussed in 3GPP. It can be said that the coverage enhancement technology (or coverage enhancement processing) for MTC UEs described below is a processing for improving or enhancing the communication characteristics or communication quality of MTC UEs. The state in which these special coverage enhancement technologies are applied to UEs is called coverage enhancement (CE) mode, coverage extension (CE) mode, enhanced coverage mode (ECM) or extended coverage mode (ECM).

[0006] The coverage enhancement technology can, for example, improve the reception characteristics of the physical broadcast channel (PBCH), the transmission characteristics of the physical random access channel (PRACH) preamble (i.e., the detection characteristics in the wireless base station (evolved NodeB (eNB))), the reception characteristics of the physical downlink control channel (PDCCH), the reception characteristics of the physical downlink shared channel (PDSCH), the transmission characteristics of the physical uplink control channel (PUCCH), and the transmission characteristics of the physical uplink shared channel (PUSCH). PBCH is a downlink broadcast channel used by the eNB to send public broadcast information in the cell. PRACH is an uplink physical channel used by the UE to initially access (i.e., randomly access) the eNB. PDCCH is a downlink physical channel used by the eNB, for example, to schedule information on downlink data (DL allocation) and to send radio resource allocation information (UL grant) for uplink data. PDSCH is a downlink physical channel used by the UE to receive system information and data. PUSCH is an uplink physical channel used by the UE to send data.

[0007] One process being discussed to improve the reception characteristics of the PBCH is to repeat the broadcast information related to the PBCH an additional number of times compared to a specific number of times in normal operation (see non-patent document 2). One process being discussed to improve the transmission characteristics of the PRACH is to repeat the transmission of the PRACH (i.e., the preamble) a specific number of times (see non-patent document 3). In addition, one process being discussed to improve the reception characteristics of the PDSCH and the transmission characteristics of the PUCCH and PUSCH is to repeat the transmission of the PDSCH, PUCCH, and PUSCH in multiple subframes (see non-patent document 4). In addition, one process being discussed to improve the reception characteristics of the M-PDCCH (i.e., the PDCCH used to transmit L1 / L2 control information for the MTC UE) is to repeat the transmission of the M-PDCCH in multiple subframes. According to the above process, the communication characteristics of the MTC UE, which are expected to be lower than the communication characteristics of the normal UE, will be improved. In the case of scheduling downlink data by repeated transmission of M-PDCCH, the M-PDCCH has been discussed as transmitting the data at a subframe after the subframe in which the last repeated transmission of M-PDCCH was performed. The M-PDCCH has also been discussed as including the number of repetitions of M-PDCCH (the actual number of repetitions to be performed) in the downlink (DL) link control information contained in the M-PDCCH.

[0008] The number of transmission repetitions and the number of reception repetitions required to improve communication characteristics depend on the installation location of the MTC UE and the path loss between the MTC UE and the eNB. Therefore, the coverage enhancement technology provides multiple coverage enhancement levels (CE levels). The coverage enhancement level (CE level) may also be referred to as an enhanced coverage level, a coverage extension level, an extended coverage level, or a repetition level (e.g., a PRACH repetition level). In addition, a one-to-one relationship or a specific relative relationship may be preconfigured between the CE level and the repetition level.

[0009] For example, in addition to normal coverage (zero coverage extension), the coverage enhancement technology provides three CE levels. These CE levels are associated with different transmission repetitions and different reception repetitions, respectively. The transmission repetitions and reception repetitions used in the high CE level are greater than the transmission repetitions and reception repetitions used in the low CE level. As the path loss between the MTC UE and the eNB increases, each MTC UE is assigned to a higher CE level. In some implementations, the MTC UE measures the reference signal received power (RSRP) from the eNB or measures the estimated path loss between the MTC UE and the eNB, determines (or estimates) the required CE level based on the measured RSRP or path loss, and then sends a random access preamble (RACH preamble) according to the maximum number of transmission repetitions associated with the determined CE level (see patent document 1).

[0010] Prior art literature

[0011] Patent Literature

[0012] [Patent Document 1] International Patent Publication WO 2015 / 021315

[0013] [Non-patent document 1] 3GPP TR 36.888V12.0.0 (2013-06), "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Studyon provision of low-cost Machine-Type Communications (MTC) User Equipments (UEs) based on LTE (Release 12)", June 2013

[0014] [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, November 11-15, 2013

[0015] [Non-Patent Document 3] 3GPP R1-135944, Vodafone, "Way Forward on PRACH for MTC enhanced coverage", 3GPP TSG RAN WG1#75, San Francisco, USA, November 11-15, 2013

[0016] [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, November 11-15, 2013 Summary of the invention

[0017] Problem that the invention aims to solve

[0018] The eNB needs to provide multiple radio resource configurations for multiple CE levels to the MTC UE supporting the coverage enhancement technology. For example, the eNB uses system information for the MTC UE (i.e., system information block x-bis (SIB x-bis)) such as SIB 1-bis or SIB 2-bis, etc., to send radio resource configurations for initial access (i.e., random access) performed by the MTC UE in the idle state in the cell. If the system information needs to explicitly include multiple radio resource configurations for multiple CE levels, the data size of the system information increases.

[0019] One of the purposes to be achieved by the embodiments disclosed herein is to provide a device, method and program that helps reduce the data size (i.e., signaling overhead) required for a base station to notify a wireless terminal of multiple wireless resource configurations for multiple coverage enhancement levels. It should be noted that this purpose is only one of the purposes to be achieved by the embodiments disclosed herein. Other purposes or problems and novel features will become apparent from the description and drawings in the specification.

[0020] Solutions for solving problems

[0021] In a first aspect, a base station includes a memory and at least one processor connected to the memory. The at least one processor is configured to send a first value of a first wireless resource configuration information element and information related to a conversion factor to a wireless terminal. The first value is associated with normal coverage or a first coverage enhancement level. The wireless terminal uses the value of the conversion factor obtained from the information related to the conversion factor to derive a second value of the first wireless resource configuration information element from the first value. The second value is associated with a second coverage enhancement level.

[0022] In a second aspect, a method in a base station includes sending a first value of a first radio resource configuration information element and information related to a conversion factor to a wireless terminal. The first value is associated with normal coverage or a first coverage enhancement level. The wireless terminal uses the value of the conversion factor obtained from the information related to the conversion factor to derive a second value of the first radio resource configuration information element from the first value. The second value is associated with a second coverage enhancement level.

[0023] In a third aspect, a wireless terminal includes a memory and at least one processor connected 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 calculating module. The receiving module is configured to receive a first value of a first wireless resource configuration information element from a base station. The first value is associated with normal coverage or a first coverage enhancement level. The calculating module is configured to derive a second value of the first wireless resource configuration information element by converting the first value using a value of a conversion factor. The second value is associated with a second coverage enhancement level.

[0024] In a fourth aspect, a method in a wireless terminal comprises: (a) receiving a first value of a first wireless resource configuration information element from a base station, wherein the first value is associated with normal coverage or a first coverage enhancement level; and (b) deriving a second value of the first wireless resource configuration information element by converting the first value using the value of a conversion factor, wherein the second value is associated with a second coverage enhancement level.

[0025] In a fifth aspect, a program includes instructions (software codes) for causing a computer to perform the method according to the second aspect or the fourth aspect when loaded into the computer.

[0026] Effects of the Invention

[0027] According to the above aspects, it is possible to provide an apparatus, method, and program that facilitate reduction of data size (ie, signaling overhead) required for a base station to notify a wireless terminal of multiple wireless resource configurations for multiple coverage enhancement levels. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a diagram showing a structural example of a wireless communication network according to various embodiments;

[0029] Figure 2 is a sequence diagram showing an example of an operation of transmitting system information according to the first embodiment;

[0030] Figure 3 is a diagram showing an example of repeated transmission of a RACH preamble;

[0031] Figure 4 is a diagram showing an example of values ​​of radio resource configuration information elements for multiple CE levels;

[0032] Figure 5 is a flowchart showing an example of the operation of the wireless terminal according to the first embodiment;

[0033] Figure 6is a diagram of a first example of calculation performed by a wireless terminal according to the first embodiment for deriving wireless resource configuration information elements;

[0034] Figure 7 is a diagram of a second example of calculation performed by the wireless terminal according to the first embodiment for deriving wireless resource configuration information elements;

[0035] Figure 8 is a diagram of a third example of calculation performed by the wireless terminal according to the first embodiment for deriving wireless resource configuration information elements;

[0036] Fig. 9 is a diagram of a fourth example of calculation performed by the wireless terminal according to the first embodiment for deriving wireless resource configuration information elements;

[0037] Fig.10 is a diagram showing an example of a random access procedure according to the first embodiment;

[0038] Fig.11 is a block diagram showing a structural example of a wireless terminal according to various embodiments; and

[0039] Fig.12 is a block diagram showing a structural example of a base station according to various embodiments. DETAILED DESCRIPTION

[0040] The specific embodiments are described in detail below with reference to the accompanying drawings. In the accompanying drawings, the same or corresponding elements are represented by the same reference numerals, and for the sake of clarity of the description, repeated description will be omitted when necessary.

[0041] The embodiments described below can be implemented individually or in combination with each other. These embodiments include novel features that are different from each other. Therefore, these embodiments help to achieve different purposes or solve different problems from each other, and also help to obtain different advantages from each other.

[0042] The following description of the embodiments mainly focuses on the Evolved Packet System (EPS) including LTE and System Architecture Evolution (SAE). However, these embodiments are not limited to application to EPS and can be applied to other mobile communication networks or systems, such as 3GPP UMTS, 3GPP2 CDMA2000 system (1xRTT, High Rate Packet Data (HRPD)), Global System for Mobile Communications (GSM (trademark)) / General Packet Radio Service (GPRS) system and WiMAX system, etc.

[0043] First embodiment

[0044] Figure 1An example of a structure of a wireless communication network according to a plurality of embodiments including this embodiment is shown. Figure 1 In the example shown, the wireless communication network includes one or more wireless terminals (i.e., MTC UEs) 1 and a base station (eNB) 2. Each MTC UE 1 is equipped with at least one wireless transceiver and is configured to perform cellular communication with the eNB 2. The eNB 2 is configured to manage a cell 21 and perform cellular communication with the MTC UE 1 using a cellular communication technology (e.g., Evolved Universal Terrestrial Radio Access (E-UTRA) technology).

[0045] Figure 1 The eNB 2 shown may be a baseband unit (BBU) used in a centralized radio access network (C-RAN) architecture. In other words, Figure 1 The eNB 2 shown may be a RAN node to be connected to one or more remote radio heads (RRHs). In some implementations, the eNB 2 used as a BBU is responsible for control plane processing and digital baseband signal processing for the user plane. On the other hand, each RRH is responsible for analog radio frequency (RF) signal processing (e.g., frequency conversion and signal amplification). C-RAN is also known as cloud RAN. BBU is also known as radio equipment controller (REC) or data unit (DU). RRH is also known as radio equipment (RE), radio unit (RU) or remote radio unit (RRU).

[0046] exist Figure 1 In the example shown, the distance between eNB 2 and MTC UE 1A is greater than the distance between eNB 2 and MTC UE 1B. Therefore, it is assumed that MTC UE 1A has a large path loss and its wireless quality is degraded. In addition, MTC UE 1C is installed inside a structure (e.g., a building), and therefore it is assumed that its wireless quality becomes lower than the wireless quality in the case where MTC UE 1C is installed outdoors. In addition, if the capabilities or functions of MTC UE 1 are limited compared to other UEs (e.g., smart phones and tablet computers) that perform interpersonal communications such as voice communication and web browsing, it is expected that the degradation of the wireless quality of MTC UE 1 will become more serious. Therefore, MTC UE 1 according to the present embodiment supports the above-mentioned coverage enhancement technology.

[0047] As described above, repetition of DL transmissions (e.g., repeated transmission of system information, M-PDCCH, and PDSCH) can be used to improve downlink (DL) cell coverage. To improve uplink (UL) cell coverage, repetition of UL transmissions (e.g., repeated transmission of RACH preamble, PUCCH, and PUSCH) can be used.

[0048] The MTC UE 1 may support multiple CE modes (or ECMs). In some implementations, the MTC UE 1 may support a CE mode (or ECM) for the RRC_IDLE state and other CE modes (or ECMs) for the RRC_CONNECTED state. Additionally or alternatively, the MTC UE 1 may support a CE mode (or ECM) for the RRC_IDLE state or a CE mode (or ECM) for the RRC_CONNECTED state. In some implementations, multiple coverage enhancement levels are defined for each CE mode (or for each ECM). Additionally or alternatively, in some implementations, multiple CE modes provide multiple coverage enhancement levels that are different from each other.

[0049] Figure 2 An example of an operation of sending system information according to this embodiment is shown (process 200). In step 201, eNB 2 sends system information (e.g., SIB1-bis, SIB2-bis) in cell 21. eNB 2 may repeatedly send system information (SIB1-bis, SIB2bis) according to the coverage enhancement configuration for DL ​​of cell 21.

[0050] The system information sent in step 201 includes information that explicitly or implicitly indicates that coverage enhancement technology (coverage enhancement solution) is supported in the cell, and control information for coverage enhancement technology (e.g., coverage enhancement configuration). In particular, the system information includes the value of the first radio resource configuration information element (IE) (hereinafter referred to as "base value"). This value is associated with normal coverage (zero coverage extension) or a first coverage enhancement (CE) level (e.g., CE level 1). The first radio resource configuration IE needs to be set to different values ​​for different CE levels. For example, the first radio resource configuration IE may involve at least one of a UL message, a UL physical channel, a DL message, and a DL physical channel, each of which is repeatedly sent during the random access process.

[0051] In some implementations, the first radio resource configuration IE may include at least one of the following IEs related to RACH configuration:

[0052] -numberOfRA-Preambles;

[0053] -maxNumPreambleAttemptCE;

[0054] -numRepetitionPerPreambleAttempt;

[0055] -ra-ResponseWindowSize;

[0056] -mac-ContentionResolutionTimer;

[0057] -maxHARQ-Msg3Tx; and

[0058] -numRepetitionPerRA-Response.

[0059] The “numberOfRA-Preambles” IE indicates the total number of random access preambles (i.e., RACH preambles) that can be used for contention-based random access. The “maxNumPreambleAttemptCE” IE indicates the maximum number of PRACH attempts (for each CE level). The “numRepetitionPerPreambleAttempt” IE indicates the number of repetitions of preamble transmission for each PRACH attempt (for each CE level). The “ra-ResponseWindowSize” IE indicates the duration of the random access (RA) response window. The “mac-ContentionResolutionTimer” IE indicates the timer value of the MAC contention resolution timer used to wait for receiving a medium access control (MAC) contention resolution message for RA contention resolution from eNB 2 after sending the third message (Msg3) in the random access procedure (i.e., the RRC connection request message) to eNB 2. The “maxHARQ-Msg3Tx” IE indicates the maximum number of hybrid automatic repeat request (HARQ) retransmissions of the third message (Msg3) in the random access procedure (i.e., the RRC connection request message). The "numRepetitionPerRA-Response" IE indicates the number of repetitions (for each CE level) of M-PDCCH transmission used to transmit the second message (Msg2) (i.e., random access response (RAR) message) in the random access procedure, or indicates the number of repetitions of RAR message transmission in the random access procedure. The names of these IEs are merely examples, and other names may be used for these IEs.

[0060] Figure 3 An example of repeated RACH preamble transmission performed by an MTC UE 1 supporting coverage enhancement technology is shown. Figure 3 In the example shown, MTC UE 1 repeats preamble transmission four times for one PRACH attempt, and performs a maximum of 20 PRACH attempts. If one attempt fails, MTC UE 1 increases the transmission power of the RACH preamble according to a power ramping scheme and starts the next attempt.

[0061] Figure 4An example of the value of the radio resource configuration information element for multiple CE levels is shown. Figure 4 In the example shown, the value of the "maxNumPreambleAttemptCE" IE associated with the minimum CE level (ie, CE level 1) is 20, and the value of the "numRepetitionPerPreambleAttempt" IE associated with the minimum CE level (ie, CE level 1) is 4. This is consistent with Figure 3 . On the other hand, in higher CE levels, the maximum number of PRACH attempts and the number of repetitions of preamble transmission for each PRACH attempt are increased. Specifically, with respect to CE level 2, the value of the "maxNumPreambleAttemptCE" IE is 60, and the value of the "numRepetitionPerPreambleAttempt" IE is 10. In addition, with respect to CE level 3, the value of the "maxNumPreambleAttemptCE" IE is 120, and the value of the "numRepetitionPerPreambleAttempt" IE is 20.

[0062] In some implementations, the first radio resource configuration IE may include at least one of the following IEs related to PRACH configuration:

[0063] -prach-ConfigIndex; and

[0064] -prach-FreqOffset.

[0065] The "prach-ConfigIndex" IE indicates a value (ie, R_Slot) used to define when the MTC UE 1 should send a random access preamble in a frequency / time grid. The "prach-FreqOffset" IE indicates a frequency offset value used to specify a physical resource block (PRB) that can be used for RACH access.

[0066] The 3GPP specification specifies a set or one-dimensional array of a predetermined number (e.g., eight) of values ​​that can be set in the radio resource configuration IE. These values ​​are, for example, arranged in ascending or descending order, and each of these values ​​is associated with an index value representing the ascending or descending level. Therefore, each radio resource configuration IE represents an index value representing any one of the values ​​included in the set or one-dimensional array. For example, in 3GPP release version 12, the RA response window size is in subframes and can have eight different values, i.e., 2, 3, 4, 5, 6, 7, 8, or 10 subframes. Therefore, the "ra-ResponseWindowSize" IE has a length of 3 bits and represents one of these eight different values ​​by a 3-bit index value.

[0067] The MTC UE 1 receives a base value of a first radio resource configuration IE associated with normal coverage (zero coverage extension, CE level 0) or a first CE level (e.g., CE level 1) from the eNB 2, and then derives a value (i.e., a second value) of the first radio resource configuration IE associated with another CE level (i.e., a second CE level (e.g., CE level 2)) from the received base value. Therefore, the MTC UE 1 does not need to receive an additional IE from the eNB 2 that explicitly indicates the second value of the first radio resource configuration IE associated with the second CE level.

[0068] More specifically, the MTC UE 1 uses the value of the conversion factor to derive a second value associated with the second CE level (e.g., CE Level 2) based on the base value received from the eNB 2. The conversion factor may be simply referred to as the factor. To support the derivation of the second value in the MTC UE 1, in some implementations, the eNB 2 may also incorporate the value of the conversion factor into the base value. Figure 2 Optionally, in some implementations, the eNB 2 may also include information indirectly indicating the value of the conversion factor or information used to derive the value of the conversion factor into the system information sent in step 201. Figure 2The system information sent in step 201 of . For example, the information indirectly indicating the value of the conversion factor may be an index specifying a value from a set of predetermined candidate values. For example, the information used to derive the value of the conversion factor may include one or more parameters to be substituted into a predetermined formula for calculating the conversion factor. That is, the eNB 2 may send information related to the conversion factor (e.g., the value of the conversion factor itself, information indirectly indicating the value of the conversion factor, or information used to derive the value of the conversion factor) to the MTC UE 1. The MTC UE 1 uses the information related to the conversion factor to obtain the value of the conversion factor. In this case, the conversion factor and the process for deriving (or calculating) the second value using the conversion factor are defined in the following manner: the data size of the information related to the conversion factor is smaller than the data size required to explicitly send the value of one or more radio resource configuration IEs associated with the second CE level from the eNB 2 to the MTC UE 1.

[0069] Before step 201, the eNB 2 may calculate the value of the conversion factor to be sent to the MTC UE 1. Specifically, the eNB 2 may determine the value of the first radio resource configuration IE for one or more second CE levels (e.g., CE levels 1 to 3), and then use the determined IE value and the base value of the first radio resource configuration IE (e.g., the IE value for CE level 0) to calculate one or more values ​​of the conversion factor for one or more second CE levels.

[0070] In another implementation, the MTC UE 1 may store a default value of the conversion factor in its memory in advance, and use the default value to derive the second value from the base value of the first radio resource configuration IE when no conversion factor is explicitly sent from the eNB 2 .

[0071] Figure 5 5 is a flow chart showing an example of the operation of the MTC UE 1 (process 500). In step 501, the MTC UE 1 receives system information including a base value of a first radio resource configuration IE from the eNB 2. As described above, the base value of the first radio resource configuration IE is a value of the first radio resource configuration IE associated with normal coverage (i.e., zero coverage extension) or a first CE level (e.g., CE level 1). The system information may also include a conversion factor for deriving a second value of the first radio resource configuration IE associated with a second CE level from the base value.

[0072] In step 502, the MTC UE 1 derives a value of the first radio resource configuration IE associated with the second CE level by converting a base value of the first radio resource configuration IE associated with normal coverage (or the first CE level) using a value of a conversion factor. The first radio resource configuration IE, for example, includes one or more RACH configuration IEs (e.g., ra-ResponseWindowSize and mac-ContentionResolutionTimer). In this case, the MTC UE 1 uses the value of the conversion factor to derive a second value associated with the first CE level (or the second CE level) from a base value of one or more RACH configuration IEs associated with normal coverage (or the first CE level).

[0073] The MTC UE 1 may calculate the reference signal received power (RSRP) from the eNB 2 or the estimated path loss between the MTC UE 1 and the eNB 2, and determine the required CE level based on the calculated RSRP or path loss. In step 503, if the MTC UE 1 requires a second CE level, the MTC UE 1 performs a random access procedure according to the second value of the first radio resource configuration IE (e.g., ra-ResponseWindowSize and mac-ContentionResolutionTimer) derived in step 502.

[0074] Some examples of conversion factors and some examples of processes for deriving (or calculating) the second value of the radio resource configuration IE from its base value using the conversion factor are provided below. Figure 6 In the first example shown, the conversion factor represents a multiplication factor. In addition, in the first example, the value of a common conversion factor (i.e., the multiplication factor) is used to derive two or more values ​​of two or more wireless resource configuration IEs (e.g., ra-ResponseWindowSize and mac-ContentionResolutionTimer) associated with the second CE level. Therefore, in the first example, eNB 2 only needs to send the value of the common conversion factor, and does not send two or more values ​​of two or more wireless resource configuration IEs associated with the second CE level. Therefore, in the first example, the data size required for the base station to notify the wireless terminal of multiple wireless resource configurations for multiple CE levels can be reduced. The conversion factor in the first example may also be referred to as a scaling factor, a coefficient, or a scaling coefficient.

[0075] More specifically, in Figure 6In the example shown, MTC UE 1 receives the values ​​of "ra-ResponseWindowSize" and "mac-ContentionResolutionTimer" IEs for normal coverage (ie, zero coverage extension or CE level 0) from eNB 2 in the form of SIB (601). Figure 6 In , the RA response window size (i.e., ra-ResponseWindowSize) for normal coverage is 2 subframes (i.e., sf2), and the length of the contention resolution timer (i.e., mac-ContentionResolutionTimer) for normal coverage is 8 subframes (i.e., sf8).

[0076] The MTC UE 1 also receives three values ​​of conversion factors (ie, multiplication factors) each associated with each of the three CE levels (ie, CE levels 1, 2, and 3) from the eNB 2 (602). Figure 6 , the values ​​of the conversion factors (ie, multiplication factors) for CE levels 1, 2 and 3 are 2, 3 and 4, respectively. Alternatively, the MTC UE 1 may receive from the eNB 2 only one value of the conversion factor corresponding to a desired one of the three CE levels.

[0077] The MTC UE 1 multiplies each of the two or more IE values ​​(601) for normal coverage by each of the values ​​of the conversion factor (multiplier factor) (603). Therefore, the MTC UE 1 is able to derive two or more values ​​(604) of the two or more IEs for each of the CE levels 1, 2, and 3. The MTC UE 1 may calculate only the value associated with one CE level required among the three CE levels.

[0078] exist Figure 7 In the second example shown, a common conversion factor value is used to calculate two or more IE values ​​for two or more CE levels. Specifically, MTC UE 1 uses the base value of the radio resource configuration IE and the value of the conversion factor to calculate the third value of the radio resource configuration IE associated with the third CE level and the second value associated with the second CE level. Therefore, in the second example, eNB 2 only needs to send the value of the common conversion factor, and does not send two or more values ​​of the first radio resource configuration IE associated with the second CE level and the third CE level. Therefore, in the second example, the data size required for the base station to notify the wireless terminal of multiple radio resource configurations for multiple CE levels can be reduced.

[0079] More specifically, in Figure 7In the example shown, MTC UE 1 receives the value of the "ra-ResponseWindowSize" IE for normal coverage (ie, zero coverage extension or CE level 0) from eNB 2 in the form of SIB (701). Figure 7 In the example, the RA response window size (ie, ra-ResponseWindowSize) for normal coverage is 2 subframes (ie, sf2).

[0080] The MTC UE 1 also receives from the eNB 2 a value of a common conversion factor (ie, a base multiplication factor) for obtaining three IE values ​​for three CE levels (ie, CE levels 1, 2, and 3) (702). Figure 7 In , the conversion factor (ie, the base multiplication factor) has a value of 2.

[0081] The MTC UE 1 multiplies the value of the radio resource configuration IE for normal coverage (701) by the value of the conversion factor (i.e., the base multiplication factor) (703). Therefore, the MTC UE 1 is able to derive the IE value for CE level 1 (704). In addition, in order to obtain the IE value for CE level 2, the MTC UE 1 multiplies the IE value for CE level 1 by the value of the conversion factor (i.e., the base multiplication factor). That is, in Figure 7 In the example shown, the value of the conversion factor (i.e., the base multiplier factor) directly or indirectly specifies the proportionality factor of the IE value for normal coverage and the corresponding IE values ​​for two or more CE levels. Therefore, the MTC UE 1 can calculate two or more IE values ​​for each of the two or more CE levels based on the value of the common conversion factor (i.e., the base multiplier factor).

[0082] exist Figure 8 In the third example shown, the conversion factor represents an offset. In the third example, as in the first example described above, one value of the conversion factor (i.e., the offset) is used to derive two or more values ​​associated with the second CE level corresponding to two or more radio resource configuration IEs (e.g., ra-ResponseWindowSize and mac-ContentionResolutionTimer). Therefore, in the third example, as in the first example, the data size required for the base station to notify the wireless terminal of multiple radio resource configurations for multiple CE levels can be reduced.

[0083] More specifically, in Figure 8In the example shown, MTC UE 1 receives the values ​​of "ra-ResponseWindowSize" and "mac-ContentionResolutionTimer" IEs for normal coverage (ie, zero coverage extension or CE level 0) from eNB 2 in the form of SIB (801). Figure 8 In , the RA response window size (i.e., ra-ResponseWindowSize) for normal coverage is 2 subframes (i.e., sf2), and the length of the contention resolution timer (i.e., mac-ContentionResolutionTimer) for normal coverage is 8 subframes (i.e., sf8).

[0084] The MTC UE 1 also receives three values ​​of conversion factors (ie, offsets) each associated with each of the three CE levels (ie, CE levels 1, 2, and 3) from the eNB 2 (802). Figure 8 , the values ​​of the conversion factors (ie, offsets) for CE levels 1, 2, and 3 are 2, 4, and 6, respectively. Alternatively, the MTC UE 1 may receive from the eNB 2 only one value of the conversion factor corresponding to a desired one of the three CE levels.

[0085] The MTC UE 1 adds the value of the conversion factor (offset) to each IE value (803) of the two or more IE values ​​(801) for normal coverage. Therefore, the MTC UE 1 is able to derive two or more values ​​(804) of the two or more IEs for each of the CE levels 1, 2, and 3. The MTC UE 1 may calculate only the value associated with one CE level required among the three CE levels.

[0086] exist Fig. 9 In the fourth example shown, as in the second example described above, two or more IE values ​​for two or more CE levels are calculated using a common conversion factor value. Therefore, in the fourth example, as in the second example, the data size required for the base station to notify the wireless terminal of multiple wireless resource configurations for multiple CE levels can be reduced. In the fourth example, a base offset is used as a conversion factor.

[0087] More specifically, in Fig. 9 In the example shown, MTC UE 1 receives the value of the "ra-ResponseWindowSize" IE for normal coverage (ie, zero coverage extension or CE level 0) from eNB 2 in the form of a SIB (eg, SIB2-bis) (901). Fig. 9 In the example, the RA response window size (ie, ra-ResponseWindowSize) for normal coverage is 2 subframes (ie, sf2).

[0088] The MTC UE 1 also receives from the eNB 2 a value of a common conversion factor (ie, base offset) for obtaining three IE values ​​for three CE levels (ie, CE levels 1, 2, and 3) (902). Fig. 9 , the conversion factor (i.e., base offset) has a value of 2.

[0089] MTC UE 1 adds the value of the conversion factor (i.e., base offset) to the value of the radio resource configuration IE for normal coverage (901)(903). Therefore, MTC UE 1 is able to derive the IE value for CE level 1 (904). In addition, in order to obtain the IE value for CE level 2, MTC UE 1 adds the value of the conversion factor (i.e., base offset) to the IE value for CE level 1. That is, in Fig. 9 In the example shown, the value of the conversion factor (i.e., the base offset) indirectly specifies the proportionality factor of the IE value for normal coverage and the corresponding IE values ​​for two or more CE levels. Therefore, the MTC UE 1 is able to calculate two or more IE values ​​for two or more CE levels based on the value of the common conversion factor (i.e., the base offset).

[0090] The fifth example is a variation of the first example described above. In the fifth example, the conversion factor represents a divisor factor. In the fifth example, as in the first example, a value of the conversion factor (i.e., the divisor factor) is used to derive two or more values ​​corresponding to two or more wireless resource configuration IEs and associated with the second CE level. In some implementations, the MTC UE 1 divides two or more values ​​corresponding to two or more IEs for normal coverage by the value of the conversion factor (i.e., the divisor factor) for each CE level. Therefore, the MTC UE 1 is able to derive two or more values ​​corresponding to two or more IEs for each CE level. The fifth example can be used to obtain a value of an IE (e.g., maxNumPreambleAttemptCE) that decreases as the CE level becomes higher.

[0091] The sixth example is a variation of the second example described above. In the sixth example, the conversion factor represents a base divisor factor. In the sixth example, as in the second example, the value of a common conversion factor is used to calculate two or more IE values ​​for two or more CE levels. In some implementations, the MTC UE 1 divides the IE value for normal coverage by the value of the conversion factor (i.e., the base divisor factor). Therefore, the MTC UE 1 is able to calculate two or more IE values ​​for two or more CE levels based on the value of the common conversion factor (i.e., the base divisor factor). The sixth example can be used to obtain a value of an IE (e.g., maxNumPreambleAttemptCE) that decreases as the CE level becomes higher.

[0092] The seventh example is a variation of the first example described above. In the seventh example, the conversion factor represents the exponent of an integer m (i.e., a power of m). In the case where the conversion factor is a positive integer k, the second value of the wireless resource configuration IE is obtained by multiplying the base value of the wireless resource configuration IE by m raised to the kth power. The value of the base "m" of the power operation may be defined by the 3GPP specification. That is, the value of the base "m" of the power operation may be pre-stored in the memory of the MTC UE 1. For example, in the case where the base "m" is equal to 2 and the value of the conversion factor for CE level 1 is 3, the second value of the wireless resource configuration IE is obtained by multiplying the base value of the wireless resource configuration IE for normal coverage (i.e., CE level 0) by 2. 3 To obtain the value of the radio resource configuration IE for CE level 1, that is, the value for CE level 1 is eight times larger than the base value. In the seventh example, as in the first example, a value of the conversion factor (i.e., exponent) is used to derive two or more values ​​associated with the second CE level (e.g., CE level 1) corresponding to two or more radio resource configuration IEs.

[0093] The first to seventh examples described above may be modified appropriately. In addition, in order to derive the second value of the radio resource configuration IE from the base value thereof using the conversion factor, a method other than the method described in the first to sixth examples may be used.

[0094] For example, in the first example to the seventh example, the value of the conversion factor is a multiplication factor, an offset, a divisor factor, or an exponent of a power operation to be used for multiplication, addition, or division of a specific value (e.g., the number of subframes) indicated by a base value (i.e., an index value) of the radio resource configuration IE. Alternatively, the value of the conversion factor may be a multiplication factor, an offset, a divisor factor, or an exponent of a power operation to be used for multiplication, addition, or division of the base value (i.e., the index value) of the radio resource configuration IE itself. For example, the base value (i.e., the index value) of the radio resource configuration IE may be multiplied by the value of the multiplication factor as the conversion factor. In this case, the specific value (e.g., the number of subframes) indicated by the converted index value is used for the corresponding CE level.

[0095] The first to seventh examples described above may be combined appropriately. For example, when a common conversion factor is used to calculate the value of each IE, the effect of the conversion factor on each IE (i.e., the calculation method for deriving the IE value) may be different. For example, the value of the conversion factor may be used as a multiplier factor for multiplication to obtain the value of one IE, while the value of the conversion factor may be used as an offset for addition to obtain the value of another IE.

[0096] In some embodiments, the value of the conversion factor used to obtain the value of the first radio resource configuration IE associated with the second CE level may also be used as a value associated with the second coverage enhancement level of a second radio resource configuration IE different from the first radio resource configuration IE. For example, the MTC UE 1 may use one or both of the value of the "numRepetitionPerPreambleAttempt" IE indicating the number of preamble repetitions (i.e., PRACH preamble repetition level) in the second CE level received from the eNB 2 and the value of the "numRepetitionPerRA-Response" IE indicating the number of RA response repetitions (i.e., RAR repetition level) in the second CE level received from the eNB 2 as conversion factors to obtain the values ​​of the "ra-ResponseWindowSize" and "mac-ContentionResolutionTimer" IEs associated with the second CE level. Additionally or alternatively, the MTC UE 1 may use one or both of the values ​​of the IE indicating the repetition level (i.e., number of repetitions) of the third message (i.e., RRC connection request message) in the random access procedure in the second CE level received from the eNB 2 and the values ​​of the IE indicating the repetition level (number of repetitions) of the fourth message (i.e., contention resolution message) in the second CE level received from the eNB 2 as conversion factors to obtain the value of the "mac-ContentionResolutionTimer" IE associated with the second CE level. In both examples, the coefficient (proportional coefficient) associating one or both of the PRACH preamble repetition level and the RAR repetition level with the ra-ResponseWindowSize may be the same as the coefficient (proportional coefficient) associating one or both of the repetition level of the third message and the repetition level of the fourth message with the mac-ContentionResolutionTimer.

[0097] In some implementations, in order to obtain an IE value corresponding to a necessary CE level in the MTC UE 1, the MTC UE 1 uses another factor in addition to the conversion factor. For example, the MTC UE 1 uses the repetition level (i.e., the number of repetitions) of the corresponding signal (e.g., preamble, message) and the conversion factor to derive the IE value. For example, the MTC UE 1 can derive the value of ra-ResponseWindowSize for the second CE level by multiplying the value of ra-ResponseWindowSize for the first CE level (e.g., CE level 0) by the value of the PRACH preamble repetition level for the second CE level (e.g., CE level 1, 2, or 3), and further multiplying the resulting value by (or adding to or dividing by) the value of the conversion factor. In this case, the value of the conversion factor can be a value representing the interval between 2 repetitions of the RACH preamble, or a value representing the interval between two repetitions of the RAR message (e.g., M-PDCCH or PDSCH).

[0098] In addition, in the case where a common conversion factor is used for multiple IEs, the MTC UE 1 can use the repetition level (i.e., the number of repetitions) of its corresponding signal (i.e., preamble or message) and the common conversion factor to derive the value of each IE. For example, the MTC UE 1 can derive the value of ra-ResponseWindowSize for the second CE level (e.g., CE level 1, 2, or 3) by multiplying the value of ra-ResponseWindowSize for the first CE level (e.g., CE level 0) by the value of the PRACH preamble repetition level or the RAR repetition level, and further multiplying the obtained value by (or adding to or dividing by) the value of the conversion factor. Similarly, MTC UE 1 can derive the value of mac-ContentioResolutionTimer for the second CE level by multiplying the value of mac-ContentioResolutionTimer for the first CE level (e.g., CE level 0) by one or both of the value of the repetition level of a third message (i.e., RRC connection request message) and the value of the repetition level of a fourth message (i.e., contention resolution message) for the second CE level (e.g., CE level 1, 2, or 3), and further multiplying the resulting value by (or adding to or dividing) a common conversion factor.

[0099] In some implementations, the value of the conversion factor may be a CE level value. For example, the value of the conversion factor may be a value (e.g., 1) representing a necessary CE level (e.g., CE level 1), or may be a value obtained by converting a value representing a CE level according to a predetermined conversion formula.

[0100] In some implementations, the derivation of the IE value of the conversion factor may be used only for one (or several) CE levels (e.g., CE level 1) among the plurality of CE levels, and the IE values ​​for the remaining CE levels (e.g., CE level 1 and CE level 2) may be derived from the IE value for the one (or several) CE level (e.g., CE level 1) according to a predetermined rule. For example, the IE value for CE level 2 may be twice as large as the IE value for CE level 1, and the IE value for CE level 3 may be three times as large as the IE value for CE level 1. Alternatively, the IE value for CE level 2 may be a value obtained by adding "offset + 2" to the IE value for CE level 1, and the IE value for CE level 3 may be a value obtained by adding "offset + 3" to the IE value for CE level 1. Alternatively, the IE value may be derived using a value corresponding to a difference (e.g., a ratio or a difference) in the repetition level (i.e., the number of repetitions) between the CE levels. For example, when the repetition level for CE level 1 is 2 and the repetition level for CE level 2 is 4, the IE value for CE level 2 can be set to a value 4 / 2 times larger than the IE value for CE level 1, that is, a value twice as large as the IE value for CE level 1.

[0101] The first example, the third example, the fifth example, and the seventh example above provide examples of jointly configuring (using) a value of a conversion factor for two or more radio resource configuration IEs. On the other hand, the second example, the fourth example, and the sixth example provide examples of jointly configuring (or using) a value of a conversion factor for two or more CE levels. Optionally, in some implementations, a value of a conversion factor may be configured (or used) for each radio resource configuration IE and for each CE level. In this case, the conversion factor is preferably defined in the following manner, namely: the bit length of the IE representing the conversion factor is less than the bit length of the radio resource configuration IE.

[0102] Fig.10 1 is a diagram showing an example (process 1000) of a random access procedure according to the present embodiment. In step 1001, MTC UE 1 determines (estimates) a necessary CE level based on a measured value of reception quality (e.g., RSRP) of a signal from eNB 2 or a measured value (estimated value) of a path loss between UE 1 and eNB 2.

[0103] In step 1002, the MTC UE 1 receives the system information (SIB) transmitted from the eNB 2 while using the coverage enhancement technology corresponding to the determined CE level (e.g., repeated transmission of the system information (SIB)). The system information includes the base value of the first radio resource configuration IE (e.g., one or more RACH configuration IEs) associated with normal coverage or the first CE level (e.g., CE level 1), and also includes information related to the conversion factor for deriving the value of the first radio resource configuration IE associated with the second CE level (e.g., CE level 2). As described above, for example, the information related to the conversion factor may include the value of the conversion factor itself, or it may be information indirectly indicating the value of the conversion factor, or information used to derive the value of the conversion factor.

[0104] In step 1003, the MTC UE 1 converts the base value of the first radio resource configuration IE associated with normal coverage (or the first CE level) using the value of the conversion factor. The value of the conversion factor can be obtained based on information related to the conversion factor received from the eNB 2. The MTC UE 1 thus derives the value of the first radio resource configuration IE associated with the determined CE level.

[0105] Thereafter, the MTC UE 1 performs a random access procedure according to the derived value of the first radio resource configuration IE (eg, one or more RACH configuration IEs) (steps 1004 to 1006).

[0106] In step 1004, if the MTC UE 1 has not successfully completed random access for the determined (estimated) CE level (e.g., CE level 1) even after the number of RACH preamble attempts reaches the maximum number, the MTC UE 1 may start RACH preamble transmission using the configuration for the next CE level (e.g., CE level 2). In this case, the MTC UE 1 may derive the configuration for the next CE level (e.g., CE level 2) (such as the values ​​of "ra-ResponseWindowSize" and "mac-ContentionResolutionTimer" IEs, etc.) when the applied CE level changes, or the MTC UE 1 may jointly derive the respective values ​​associated with the respective CE levels in advance.

[0107] In step 1004, the MTC UE 1 may start the RA response window at the third subframe after the start or end of repeated transmission in one RACH preamble transmission attempt in step 1004 according to the "ra-ResponseWindowSize" IE. The "ra-ResponseWindowSize" IE indicates the time that the MTC UE 1 should wait for receiving a random access response (RAR) in step 1006 after sending the RACH preamble in step 1004. In addition, the MTC UE 1 may start the contention resolution timer after the start or end of repeated third message (Msg3) transmission in the random access procedure according to the "mac-ContentionResolutionTimer" IE. The "mac-ContentionResolutionTimer" IE indicates the time that the MTC UE 1 should wait for receiving a contention resolution message (confirmation of the content) after sending the third message (Msg3).

[0108] In step 1005, the eNB 2 detects a random access (RA) preamble (i.e., a RACH preamble) transmitted from the MTC UE 1. For example, the eNB 2 determines the CE level of the MTC UE 1 based on the radio resources in which the RA preamble has been detected. Then, the eNB 2 performs coverage enhancement operations, including repeated reception of RA preambles and repeated transmission of RA responses, according to the values ​​of multiple IEs (e.g., "numRepetitionPerPreambleAttempt" and "ra-ResponseWindowSize" IEs) corresponding to the CE level determined for the MTC UE 1. In some implementations, the eNB 2 may calculate the values ​​of multiple IEs corresponding to the CE level determined for the MTC UE 1 based on the value of the conversion factor for the CE level. In some other implementations, the eNB 2 may calculate the values ​​of multiple IEs corresponding to the CE level determined for the MTC UE 1 by referring to a lookup table storing the values ​​of each IE corresponding to each CE level.

[0109] The above specific example provides a method for deriving values ​​associated with each CE level for existing radio parameters (i.e., IEs in RRC messages) related to the random access process. Similarly, the above derivation method can be used to derive values ​​associated with each CE level for the newly defined radio parameters (i.e., IEs in RRC messages) for coverage enhancement technology. For example, the above derivation method can be applied to an IE representing the maximum number of RACH preamble attempts for each CE level (i.e., maxNumPreambleAttemptCE) and an IE representing the maximum number of repetitions for each RACH preamble attempt (i.e., numRepetitionPerPreambleAttempt). In this case, the eNB 2 can send an IE value corresponding to the lowest CE level (e.g., CE level 1) via system information, and the UE 1 can use the above conversion factor to derive IE values ​​corresponding to one or more higher CE levels (e.g., CE level 2 or a CE level higher than CE level 2).

[0110] The above random access procedure can be applied not only to the initial access when the UE switches from the RRC_IDLE state to the RRC_CONNECTED state, but also to the random access in the RRC_CONNECTED state. In addition, in the case of random access in response to an indication from the eNB 2 (i.e., the PDCCH order), the indication may include at least one of a base value and a conversion factor.

[0111] The following provides a structural example of the MTC UE 1 and the eNB 2 according to this embodiment. Fig.11 1 is a block diagram showing a structural example of an MTC UE 1. A radio frequency (RF) transceiver 1101 performs analog RF signal processing to communicate with an eNB 2. The analog RF signal processing performed by the RF transceiver 1101 includes up-frequency conversion, down-frequency conversion, and amplification. The RF transceiver 1101 is connected to an antenna 1102 and a baseband processor 1103. That is, the RF transceiver 1101 receives modulation symbol data (or OFDM symbol data) from the baseband processor 1103, generates a transmit RF signal, and supplies the transmit RF signal to the antenna 1102. In addition, the RF transceiver 1101 generates a baseband receive signal based on the receive RF signal received by the antenna 1102, and supplies the baseband receive signal to the baseband processor 1103.

[0112] The baseband processor 1103 performs digital baseband signal processing (i.e., data plane processing) and control plane processing for wireless communication. Digital baseband signal processing includes (a) data compression / decompression, (b) data segmentation / concatenation, (c) combination / decomposition of transmission formats (i.e., transmission frames), (d) channel coding / decoding, (e) modulation (i.e., symbol mapping) / demodulation, and (f) generation of OFDM symbol data (i.e., baseband OFDM signal) by inverse fast Fourier transform (IFFT). On the other hand, control plane processing includes communication management of layer 1 (e.g., transmit power control), layer 2 (e.g., radio resource management and hybrid automatic repeat request (HARQ) processing), and layer 3 (e.g., signaling related to attachment, mobility and packet communication).

[0113] For example, in the case of LTE and Advanced LTE, the digital baseband signal processing performed by the baseband processor 1103 may include signal processing of a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, a MAC layer, and a PHY layer. In addition, the control plane processing performed by the baseband processor 1103 may include processing of a non-access stratum (NAS) protocol, an RRC protocol, and a MAC CE.

[0114] The baseband processor 1103 may include a modem-processor (e.g., a digital signal processor (DSP)) for performing digital baseband signal processing, and a protocol stack-processor (e.g., a central processing unit (CPU) or a microprocessing unit (MPU)) for performing control plane processing. In this case, the protocol stack-processor for performing control plane processing may be integrated with the application processor 1104 described below.

[0115] The application processor 1104 is also referred to as a CPU, an MPU, a microprocessor, or a processor core. The application processor 1104 may include a plurality of processors (processor cores). The application processor 1104 executes a system software program (operating system (OS)) and various application programs (e.g., a communication application for acquiring metering data or sensing data) loaded from the memory 1106 or from another memory (not shown), thereby providing various functions of the MTC UE 1.

[0116] In some implementations, such as Fig.11 As shown by the dotted line (1105) in FIG. 1 , the baseband processor 1103 and the application processor 1104 may be integrated on a single chip. In other words, the baseband processor 1103 and the application processor 1104 may be implemented in a single system on chip (SoC) device 1105. The SoC device may be referred to as a system large scale integration (LSI) or a chipset.

[0117] The memory 1106 is a volatile memory, a non-volatile memory, or a combination thereof. The memory 1106 may include a plurality of memory devices that are physically independent of each other. The volatile memory is, for example, a static random access memory (SRAM), a dynamic RAM (DRAM), or a combination thereof. The non-volatile memory is, for example, a mask read-only memory (MROM), an electrically erasable programmable ROM (EEPROM), a flash memory, a hard disk drive, or any combination thereof. The memory 1106 may, for example, include an external memory device accessible from the baseband processor 1103, the application processor 1104, and the SoC 1105. The memory 1106 may include an internal memory device integrated in the baseband processor 1103, the application processor 1104, or the SoC 1105. In addition, the memory 1106 may include a memory in a universal integrated circuit card (UICC).

[0118] The memory 1106 may store one or more software modules (computer programs) 1107 including instructions and data for performing the processing performed by the MTC UE 1 described in the above embodiments. In some implementations, the baseband processor 1103 or the application processor 1104 may load the software module 1107 from the memory 1106 and execute the loaded software module, thereby performing the processing of the MTC UE 1 described in the above embodiments.

[0119] Fig.12 2 is a block diagram showing a configuration example of a base station (eNB) 2 according to the above-described embodiment. Fig.12 , the eNB 2 includes an RF transceiver 1201, a network interface 1203, a processor 1204, and a memory 1205. The RF transceiver 1201 performs analog RF signal processing to communicate with the wireless terminal 1. The RF transceiver 1201 may include a plurality of transceivers. The RF transceiver 1201 is connected to an antenna 1202 and a processor 1204. The RF transceiver 1201 receives modulation symbol data (or OFDM symbol data) from the processor 1204, generates a transmit RF signal, and supplies the transmit RF signal to the antenna 1202. In addition, the RF transceiver 1201 generates a baseband receive signal based on the receive RF signal received by the antenna 1202, and supplies the baseband receive signal to the processor 1204.

[0120] The network interface 1203 is used to communicate with network nodes (eg, a mobility management entity (MME) and a serving gateway (S-GW)). The network interface 1203 may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series.

[0121] The 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 Advanced LTE, the digital baseband signal processing performed by the processor 1204 may include signal processing of the PDCP layer, the RLC layer, the MAC layer, and the PHY layer. In addition, the control plane processing performed by the processor 1204 may include processing of the S1 protocol, the RRC protocol, and the MAC CE.

[0122] The processor 1204 may include a plurality of processors. The processor 1204 may include, for example, a modem-processor (eg, DSP) for performing digital baseband signal processing, and a protocol stack-processor (eg, CPU or MPU) for performing control plane processing.

[0123] The memory 1205 includes a combination of volatile memory and non-volatile memory. The volatile memory is, for example, SRAM, DRAM, or a combination thereof. The non-volatile memory is, for example, MROM, PROM, flash memory, hard disk drive, or any combination thereof. The memory 1205 may include a memory located away from the processor 1204. In this case, the processor 1204 may access the memory 1205 via the network interface 1203 or an I / O interface (not shown).

[0124] The memory 1205 may store a software module (computer program) 1206 including instructions and data for performing the processing performed by the eNB 2 described in the above embodiments. In some implementations, the processor 1204 may load the software module 1206 from the memory 1205 and execute the loaded software module, thereby performing the processing of the eNB 2 described in the above embodiments.

[0125] As mentioned above Fig.11 and 12As described, the respective processors included in the MTC UE 1 and the eNB 2 according to the above-mentioned embodiment execute one or more programs including instructions for causing the computer to perform the algorithm described with reference to the accompanying drawings. Any type of non-transitory computer-readable medium can be used to store and provide the program to the computer. Non-transitory computer-readable media include any type of tangible storage media. Examples of non-transitory computer-readable media include: magnetic storage media (such as flexible disks, magnetic tapes, and hard disk drives, etc.); optical magnetic storage media (such as magneto-optical disks, etc.); compact disk read-only memory (CD-ROM); CD-R; CD-R / W; and semiconductor memory (such as mask ROM, programmable ROM (PROM), erasable PROM (EPROM), flash ROM, and RAM (random access memory)). Any type of temporary computer-readable medium can be used to provide the program to the computer. Examples of temporary computer-readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can provide the program to the computer via a wired communication line (for example, electric wires and optical fibers, etc.) or a wireless communication line.

[0126] Other embodiments

[0127] The above embodiments have been described with respect to radio resource configuration IEs related to random access (e.g., RACH configuration IE and PRACH configuration IE). However, the method described in the above embodiments for deriving IE values ​​for specific CE levels using conversion factors can be widely used in other applications that require different radio resource configurations for different coverage enhancement (CE) levels. The method described in the above embodiments can, for example, be used to derive the value of the radio resource configuration IE required when an MTC UE 1 in an RRC_CONNECTED state uses a specific CE level to perform UL user data transmission on a PUSCH, transmission of L1 / L2 control information on a PUCCH, reception of system information or DL ​​user data on a PDSCH, and reception of L1 / L2 control information on an M-PDCCH (e.g., the number of repetitions of transmission (or reception)).

[0128] The above embodiment has been described with respect to the case where the eNB 2 transmits the information related to the conversion factor via the system information. However, the information related to the conversion factor may be transmitted by the eNB 2 using a signal (e.g., RRC signaling, MAC signaling) used to transmit the dedicated control information to the MTC UE 1. For example, the information related to the conversion factor may be transmitted from the eNB 2 to the MTC UE 1 via an RRC connection reconfiguration message or a MAC control element. In the case where the MTC UE 1 has received the information related to the conversion factor in both the system information and the dedicated control information, the MTC UE 1 may preferably use the value of the conversion factor obtained from the information related to the conversion factor received in the dedicated control information (i.e., overwrite the value of the conversion factor obtained from the system information with the value of the conversion factor obtained from the dedicated control information).

[0129] The operations of the MTC UE 1 and the eNB 2 related to the derivation of the IE value using the conversion factor described in the above embodiments can be used to derive the value of the timer using different timer lengths according to the coverage enhancement (CE) level. Specific examples of timers using different timer values ​​for different CE levels include, for example, (1) timers associated with control of call processing, etc. (i.e., RRC, NAS), (2) timers associated with layer 2 (i.e., PDCP, RLC, MAC) control, and (3) timers used in the RRC_IDLE state.

[0130] For example, the above-mentioned timer (1) may be a timer (i.e., timer T300) for determining the success or failure of the RRC connection establishment. The MTC UE 1 starts the timer (i.e., timer T300) when sending the RRC connection re-establishment request message, and stops the timer when receiving a response (i.e., an RRC connection setup message or an RRC connection rejection message) from the eNB 2.

[0131] Additionally or alternatively, the above-mentioned timer (1) may be a timer (i.e., timer T311) for determining the success or failure of the detection of a suitable cell. The MTC UE 1 starts the timer (i.e., timer T311) when initiating the RRC connection re-establishment procedure, and stops the timer when a suitable cell is detected (or selected).

[0132] Additionally or alternatively, the above-mentioned timer (1) may be a timer (i.e., timer T304) for determining the success or failure of handover. The MTC UE 1 starts the timer (i.e., timer T304) when receiving the RRC connection reconfiguration message (i.e., a message indicating handover) including the MobilityControlInfo IE, and stops the timer when the random access procedure to the target cell is successfully completed.

[0133] For example, the above-mentioned timer (2) can be a timer for control of the MAC layer. Specific examples of timers for control of the MAC layer include: timers related to discontinuous reception control (discontinuous reception (DRX)) in the UE (e.g., OnDurationTimer, drx-InactivityTimer, drx-RetransmissionTimer, HART RTT Timer); timers for measuring the time period during which the sending of a scheduling request (SR) is prohibited (e.g., sr-ProhibitTimer, logicalChannelSR-ProhibitTimer); timers related to reporting of the uplink buffer amount (i.e., buffer status report (BSR)) (e.g., PeriodicBSR-Timer, RetxBSR-Timer); and timers related to reporting of the remaining amount of uplink transmission power (power headroom report (PHR)) (e.g., periodicPHR-Timer, prohibitPHR-Timer).

[0134] Additionally or alternatively, the above-mentioned timer (2) may be a timer for control of the RLC layer. Specific examples of the timer for control of the RLC layer include: a timer for detecting loss of an RLC PDU and performing sequence control in DL data reception (e.g., T-Reordering), and a timer for measuring a time period for prohibiting transmission of information related to the status of DL data reception (i.e., STATUS PDU) (e.g., T-StatusProhibit).

[0135] Additionally or alternatively, the timer (2) may be a timer used for PDCP layer control. Specific examples of the timer used for PDCP layer control include a timer (eg, discardTimer) used to determine whether to discard pending data in UL data transmission.

[0136] For example, the timer (3) may be a timer used in the cell reselection process performed by the MTC UE 1 in the RRC_IDLE state. Specifically, the timer (3) may be a timer used to measure the time period (ie, T-Reselection) that satisfies the conditions for triggering cell reselection.

[0137] The above timers may be started from the first or last transmission of the repeated transmission of the signal (or message) associated with each timer (or used as a trigger for each timer). Alternatively, the timers may be started from the first or last reception of the repeated reception of the signal (or message) associated with each timer (or used as a trigger for each timer).

[0138] In the above embodiment, the wireless terminal 1 may be a non-MTC UE. That is, the above embodiment may be widely applied to communication between a UE and an eNB that supports a coverage enhancement technology including repeated transmission (or reception).

[0139] Furthermore, the above-described embodiments may be applied not only to LTE, LTE-Advanced and their variants, but also to communications between wireless terminals and base stations supporting coverage enhancement technologies in other wireless communication networks or systems.

[0140] For example, the above embodiments can be applied to the coverage enhancement technology in the system called narrowband-Internet of Things (NB-IoT) that has been discussed in 3GPP. In cellular networks, NB-IoT is designed to accommodate IoT devices with low cost and ultra-low power consumption characteristics (for example, the terminal can run for ten years without replacing the battery). The purpose and device characteristics in NB-IoT are very similar to Rel-13 MTC, and it has been discussed to reuse 3GPP Release 13 (Rel-13) MTC technology for NB-IoT. Therefore, the above embodiments can be applied to NB-IoT. Although the Rel-13 MTC UE sends a RACH preamble in random access, it has been discussed that the NB-IoT UE sends a message (for example, a contention-based message) on the PRACH instead of the preamble. As described above, although it has been discussed to modify the Rel-13 MTC for NB-IoT or introduce new functions into NB-IoT, the above embodiments can be applied to NB-IoT regardless of the differences between them.

[0141] In addition, the above-mentioned embodiments are merely examples related to the application of the technical ideas obtained by the present inventors. Needless to say, these technical ideas are not limited to the above-mentioned embodiments, and various modifications can be made to these technical ideas.

[0142] For example, all or part of the above embodiments may be described as, but not limited to, the following supplementary explanations.

[0143] (Supplementary Note A1)

[0144] A base station, comprising:

[0145] Memory; and

[0146] at least one processor connected to the memory and configured to send a first value of a first radio resource configuration information element and information related to a conversion factor to a wireless terminal, the first value being associated with normal coverage or a first coverage enhancement level, wherein

[0147] The wireless terminal uses the value of the conversion factor obtained from the information related to the conversion factor to derive a second value of the first radio resource configuration information element from the first value, the second value being associated with a second coverage enhancement level.

[0148] (Supplementary Note A2)

[0149] The base station according to Supplementary Note A1, wherein:

[0150] The first radio resource configuration information element includes two or more radio resource configuration information elements,

[0151] The second value comprises two or more values ​​of the two or more radio resource configuration information elements, the two or more values ​​being associated with the second coverage enhancement level, and

[0152] The wireless terminal uses the value of the conversion factor to derive each of the two or more values ​​from the first value.

[0153] (Supplementary Note A3)

[0154] A base station according to Supplementary Note A1, wherein, in addition to the wireless terminal using the value of the conversion factor to derive the second value from the first value, the wireless terminal uses the value of the conversion factor to derive a third value of the first wireless resource configuration information element from the first value, and the third value is associated with a third coverage enhancement level.

[0155] (Supplementary Note A4)

[0156] The base station according to supplementary note A3, wherein the value of the conversion factor directly or indirectly specifies a scaling factor between the first value, the second value and the third value.

[0157] (Supplementary Note A5)

[0158] A base station according to any one of Supplementary Notes A1 to A4, wherein:

[0159] The value of the conversion factor includes the value of the multiplication factor, and

[0160] The second value is calculated by multiplying the first value by the value of the multiplication factor.

[0161] (Supplementary Note A6)

[0162] A base station according to any one of Supplementary Notes A1 to A4, wherein:

[0163] The value of the conversion factor includes an offset value, and

[0164] The second value is calculated by adding the offset value to the first value.

[0165] (Supplementary Note A7)

[0166] According to a base station described in any one of supplementary instructions A1 to A4, the value of the conversion factor is also used to derive the value of a second wireless resource configuration information element different from the first wireless resource configuration information element, and the value of the second wireless resource configuration information element is associated with the second coverage enhancement level.

[0167] (Supplementary Note A8)

[0168] A base station according to any one of Supplementary Notes A1 to A7, wherein:

[0169] The first radio resource configuration information element includes at least one parameter related to a random access procedure, and

[0170] The at least one parameter includes at least one of the following: (a) a parameter defining frequency and time resources that can be used to send a random access preamble; (b) a parameter indicating the total number of random access preambles; (c) a parameter indicating the maximum number of attempts to send a random access preamble; (d) the number of repetitions of the random access preamble transmission for each attempt to send a random access preamble; (e) a parameter indicating the duration of a random access response window; (f) a parameter indicating the duration of a contention resolution timer; (g) the maximum number of repetitions of random access response transmissions performed by the base station; and (h) a parameter indicating the maximum number of retransmissions of a third message in response to reception of a random access response.

[0171] (Supplementary Note A9)

[0172] The base station according to any one of Supplementary Notes A1 to A8, wherein the at least one processor is further configured to:

[0173] calculating a value of the conversion factor to be sent to the wireless terminal using the first value and the second value; and

[0174] The calculated value of the conversion factor is sent to the wireless terminal.

[0175] (Supplementary Note B1)

[0176] A wireless terminal, comprising:

[0177] Memory; and

[0178] At least one processor connected to the memory and configured to execute at least one module including:

[0179] a receiving module configured to receive a first value of a first radio resource configuration information element from a base station, wherein the first value is associated with normal coverage or a first coverage enhancement level; and

[0180] A calculation module is configured to derive a second value of the first radio resource configuration information element by converting the first value using a value of a conversion factor, wherein the second value is associated with a second coverage enhancement level.

[0181] (Supplementary Note B2)

[0182] The wireless terminal according to Supplementary Note B1, wherein:

[0183] The first radio resource configuration information element includes two or more radio resource configuration information elements,

[0184] The second value comprises two or more values ​​of the two or more radio resource configuration information elements, the two or more values ​​being associated with the second coverage enhancement level, and

[0185] The calculation module is configured to use the value of the conversion factor to derive each of the two or more values ​​from the first value.

[0186] (Supplementary Note B3)

[0187] A wireless terminal according to Supplementary Note B1, wherein, in addition to the calculation module being configured to use the value of the conversion factor to derive the second value from the first value, the calculation module is also configured to use the value of the conversion factor to derive a third value of the first wireless resource configuration information element from the first value, and the third value is associated with a third coverage enhancement level.

[0188] (Supplementary Note B4)

[0189] The wireless terminal according to supplementary note B3, wherein the value of the conversion factor directly or indirectly specifies a scaling factor between the first value, the second value, and the third value.

[0190] (Supplementary Note B5)

[0191] The wireless terminal according to any one of supplementary notes B1 to B4, wherein the at least one processor is further configured to receive information related to the conversion factor from the base station to obtain a value of the conversion factor.

[0192] (Supplementary Note B6)

[0193] A wireless terminal according to any one of supplementary notes B1 to B5, wherein:

[0194] The value of the conversion factor includes the value of the multiplication factor, and

[0195] The second value is calculated by multiplying the first value by the value of the multiplication factor.

[0196] (Supplementary Note B7)

[0197] A wireless terminal according to any one of supplementary notes B1 to B5, wherein:

[0198] The value of the conversion factor includes an offset value, and

[0199] The second value is calculated by adding the offset value to the first value.

[0200] (Supplementary Note B8)

[0201] According to the wireless terminal described in Supplementary Note B5, the value of the conversion factor is also used to derive the value of a second wireless resource configuration information element different from the first wireless resource configuration information element, and the value of the second wireless resource configuration information element is associated with the second coverage enhancement level.

[0202] (Supplementary Note B9)

[0203] A wireless terminal according to any one of supplementary notes B1 to B8, wherein:

[0204] The at least one module further comprises:

[0205] an estimation module configured to estimate a coverage enhancement level that the wireless terminal should comply with; and

[0206] a communication module configured to communicate with the base station according to a value of the first radio resource configuration information element associated with the estimated coverage enhancement level, and

[0207] The calculation module is configured to calculate the second value as a value of the first radio resource configuration information element associated with the estimated coverage enhancement level.

[0208] (Supplementary Note B10)

[0209] A wireless terminal according to any one of supplementary notes B1 to B9, wherein:

[0210] The first radio resource configuration information element includes at least one parameter related to a random access procedure, and

[0211] The at least one parameter includes at least one of the following: (a) a parameter defining frequency and time resources that can be used to send a random access preamble; (b) a parameter indicating the total number of random access preambles; (c) a parameter indicating the maximum number of attempts to send a random access preamble; (d) the number of repetitions of the random access preamble transmission for each attempt to send a random access preamble; (e) a parameter indicating the duration of a random access response window; (f) a parameter indicating the duration of a contention resolution timer; (g) the maximum number of repetitions of random access response transmissions performed by the base station; and (h) a parameter indicating the maximum number of retransmissions of a third message in response to reception of a random access response.

[0212] This application is based upon and claims the benefit of priority from Japanese patent application No. 2015-217963, filed on Nov. 5, 2015, the disclosure of which is incorporated herein in its entirety by reference.

[0213] Reference numerals list

[0214] 1 Wireless Terminal (UE)

[0215] 2 Base Station (eNB)

[0216] 1101 Radio Frequency (RF) Transceiver

[0217] 1103 Baseband Processor

[0218] 1104 Application Processor

[0219] 1106 Memory

[0220] 1201 RF Transceiver

[0221] 1204 Processor

[0222] 1205 Memory

Claims

1. A base station, comprising: Memory; as well as at least one processor connected to the memory and configured to send system information to the wireless terminal, the system information comprising a first value of ra-ResponseWindowSize associated with normal coverage and a multiplier factor corresponding to a coverage enhancement level, wherein The multiplication factor corresponding to the coverage enhancement level is configured to enable the wireless terminal to derive a second value of the RA-ResponseWindowSize from the first value, the second value being associated with the coverage enhancement level, The multiplication factor is also used as a third value for the number of repetitions of a random access response, ie, RAR, of a random access procedure, the third value being associated with the coverage enhancement level.

2. The base station according to claim 1, wherein: The system information also includes a fourth value of mac-ContentionResolutionTimer, and The multiplication factor corresponding to the coverage enhancement level is configured to enable the wireless terminal to derive a fifth value of the mac-ContentionResolutionTimer from the fourth value, the fifth value being associated with the coverage enhancement level.

3. A method in a base station, the method comprising: Sending system information to a wireless terminal, the system information including a first value of ra-ResponseWindowSize associated with normal coverage and a multiplication factor corresponding to a coverage enhancement level, wherein: The multiplication factor corresponding to the coverage enhancement level is configured to enable the wireless terminal to derive a second value of the RA-ResponseWindowSize from the first value, the second value being associated with the coverage enhancement level, The multiplication factor is also used as a third value for the number of repetitions of a random access response, ie, RAR, of a random access procedure, the third value being associated with the coverage enhancement level.

4. A wireless terminal, comprising: Memory; as well as at least one processor connected to the memory and configured to: receiving system information from a base station, the system information comprising a first value of ra-ResponseWindowSize associated with normal coverage and a multiplication factor corresponding to a coverage enhancement level; as well as A second value of the ra-ResponseWindowSize is derived by multiplying the first value by the multiplication factor corresponding to the coverage enhancement level, the second value being associated with the coverage enhancement level, wherein The multiplication factor is also used as a third value for the number of repetitions of a random access response, ie, RAR, of a random access procedure, the third value being associated with the coverage enhancement level.

5. The wireless terminal according to claim 4, wherein: The system information also includes a fourth value of mac-ContentionResolutionTimer, and The at least one processor is configured to derive a fifth value of the mac-ContentionResolutionTimer by multiplying the fourth value by the multiplication factor corresponding to the coverage enhancement level, the fifth value being associated with the coverage enhancement level.

6. A method in a wireless terminal, the method comprising: receiving system information from a base station, the system information comprising a first value of ra-ResponseWindowSize associated with normal coverage and a multiplication factor corresponding to a coverage enhancement level; as well as A second value of the ra-ResponseWindowSize is derived by multiplying the first value by the multiplication factor corresponding to the coverage enhancement level, the second value being associated with the coverage enhancement level, wherein The multiplication factor is also used as a third value for the number of repetitions of a random access response, ie, RAR, of a random access procedure, the third value being associated with the coverage enhancement level.

7. The method according to claim 6, wherein: The system information also includes a fourth value of mac-ContentionResolutionTimer, and The method further includes deriving a fifth value of the mac-ContentionResolutionTimer by multiplying the fourth value by the multiplication factor corresponding to the coverage enhancement level, the fifth value being associated with the coverage enhancement level.

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