KR20160135021A - Methods for configuring a CQI using MEC UE and Apparatuses thereof - Google Patents

Abstract

The present invention relates to a CQI configuration and transmission method. And more particularly, to a CQI configuration method and apparatus for an MTC terminal. The present invention provides a coverage extended MTC terminal with a CQI table used by the MTC terminal including the coverage and extended coverage of the general LTE terminal so that the base station can check the geometry level of the MTC terminal and the CQI table used by the MTC terminal And provides CQI feedback to the base station.

Description

[0001] The present invention relates to a method and apparatus for configuring a CQI for a MTC terminal,

The present invention relates to a CQI configuration and transmission method. And more particularly, to a CQI configuration method and apparatus for an MTC terminal.

The present invention provides a coverage extended MTC terminal with a CQI table used by the MTC terminal including the coverage and extended coverage of the general LTE terminal so that the base station can check the geometry level of the MTC terminal and the CQI table used by the MTC terminal And provides CQI feedback to the base station.

1 is a graph showing BLER performance for 15 spectral efficiencies used in LTE CQI.
2 is a diagram illustrating a configuration of a base station according to another embodiment of the present invention.
3 is a diagram illustrating a configuration of a user terminal according to another embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Herein, the MTC terminal may mean a terminal supporting low cost (or low complexity) or a terminal supporting coverage enhancement. In this specification, the MTC terminal may mean a terminal supporting low cost (or low complexity) and coverage enhancement. Alternatively, the MTC terminal may refer to a terminal defined in a specific category for supporting low cost (or low complexity) and / or coverage enhancement.

In other words, the MTC terminal in this specification may mean a newly defined 3GPP Release-13 low cost (or low complexity) UE category / type for performing LTE-based MTC-related operations. Alternatively, the MTC terminal may support enhanced coverage over the existing LTE coverage or a UE category / type defined in the existing 3GPP Release-12 or lower that supports low power consumption, or a newly defined Release-13 low cost low complexity UE category / type.

The wireless communication system in the present invention is widely deployed to provide various communication services such as voice, packet data and the like. A wireless communication system includes a user equipment (UE) and a base station (BS, or eNB). The user terminal in this specification is a comprehensive concept of a terminal in wireless communication. It is a comprehensive concept which means a mobile station (MS), a user terminal (UT), an SS (User Equipment) (Subscriber Station), a wireless device, and the like.

A base station or a cell generally refers to a station that communicates with a user terminal and includes a Node-B, an evolved Node-B (eNB), a sector, a Site, a BTS A base transceiver system, an access point, a relay node, a remote radio head (RRH), a radio unit (RU), and a small cell.

That is, the base station or the cell in this specification is interpreted as a comprehensive meaning indicating a partial region or function covered by BSC (Base Station Controller) in CDMA, NodeB in WCDMA, eNB in LTE or sector (site) And covers various coverage areas such as megacell, macrocell, microcell, picocell, femtocell and relay node, RRH, RU, and small cell communication range.

Since the various cells listed above exist in the base station controlling each cell, the base station can be interpreted into two meanings. i) a device itself providing a megacell, a macrocell, a microcell, a picocell, a femtocell, or a small cell in relation to a wireless region, or ii) the wireless region itself. i indicate to the base station all devices that are controlled by the same entity or that interact to configure the wireless region as a collaboration. An eNB, an RRH, an antenna, an RU, an LPN, a point, a transmission / reception point, a transmission point, a reception point, and the like are exemplary embodiments of a base station according to a configuration method of a radio area. ii) may indicate to the base station the wireless region itself that is to receive or transmit signals from the perspective of the user terminal or from a neighboring base station.

Therefore, a base station is collectively referred to as a megacell, a macrocell, a microcell, a picocell, a femtocell, a small cell, an RRH, an antenna, an RU, a low power node (LPN), a point, an eNB, Quot;

Herein, the user terminal and the base station are used in a broad sense as the two transmitting and receiving subjects used to implement the technical or technical idea described in this specification, and are not limited by a specific term or word. The user terminal and the base station are used in a broad sense as two (uplink or downlink) transmitting and receiving subjects used to implement the technology or technical idea described in the present invention, and are not limited by a specific term or word. Here, an uplink (UL, or uplink) means a method of transmitting / receiving data to / from a base station by a user terminal, and a downlink (DL or downlink) .

There are no restrictions on multiple access schemes applied to wireless communication systems. Various multiple access schemes such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), OFDM-FDMA, OFDM- Can be used. An embodiment of the present invention can be applied to asynchronous wireless communication that evolves into LTE and LTE-advanced via GSM, WCDMA, and HSPA, and synchronous wireless communication that evolves into CDMA, CDMA-2000, and UMB. The present invention should not be construed as limited to or limited to a specific wireless communication field and should be construed as including all technical fields to which the idea of the present invention can be applied.

A TDD (Time Division Duplex) scheme in which uplink and downlink transmissions are transmitted using different time periods, or an FDD (Frequency Division Duplex) scheme in which they are transmitted using different frequencies can be used.

In a system such as LTE and LTE-A, the uplink and downlink are configured based on one carrier or carrier pair to form a standard. The uplink and the downlink are divided into a Physical Downlink Control Channel (PDCCH), a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid ARQ Indicator CHannel, a Physical Uplink Control CHannel (PUCCH), an Enhanced Physical Downlink Control Channel (EPDCCH) Transmits control information through the same control channel, and is configured with data channels such as PDSCH (Physical Downlink Shared CHannel) and PUSCH (Physical Uplink Shared CHannel), and transmits data.

On the other hand, control information can also be transmitted using EPDCCH (enhanced PDCCH or extended PDCCH).

In this specification, a cell refers to a component carrier having a coverage of a signal transmitted from a transmission point or a transmission point or transmission / reception point of a signal transmitted from a transmission / reception point, and a transmission / reception point itself .

The wireless communication system to which the embodiments are applied may be a coordinated multi-point transmission / reception system (CoMP system) or a coordinated multi-point transmission / reception system in which two or more transmission / reception points cooperatively transmit signals. antenna transmission system, or a cooperative multi-cell communication system. A CoMP system may include at least two multipoint transmission / reception points and terminals.

The multi-point transmission / reception point includes a base station or a macro cell (hereinafter referred to as 'eNB'), and at least one mobile station having a high transmission power or a low transmission power in a macro cell area, Lt; / RTI >

Hereinafter, a downlink refers to a communication or communication path from a multiplex transmission / reception point to a terminal, and an uplink refers to a communication or communication path from a terminal to a multiplex transmission / reception point. In the downlink, a transmitter may be a part of a multipoint transmission / reception point, and a receiver may be a part of a terminal. In the uplink, the transmitter may be a part of the terminal, and the receiver may be a part of multiple transmission / reception points.

Hereinafter, a situation in which a signal is transmitted / received through a channel such as PUCCH, PUSCH, PDCCH, EPDCCH, and PDSCH is expressed as 'PUCCH, PUSCH, PDCCH, EPDCCH and PDSCH are transmitted and received'.

In the following description, an indication that a PDCCH is transmitted or received or a signal is transmitted or received via a PDCCH may be used to mean transmitting or receiving an EPDCCH or transmitting or receiving a signal through an EPDCCH.

That is, the physical downlink control channel described below may mean a PDCCH, an EPDCCH, or a PDCCH and an EPDCCH.

Also, for convenience of description, EPDCCH, which is an embodiment of the present invention, may be applied to the portion described with PDCCH, and EPDCCH may be applied to the portion described with EPDCCH according to an embodiment of the present invention.

Meanwhile, the High Layer Signaling described below includes RRC signaling for transmitting RRC information including RRC parameters.

The eNB performs downlink transmission to the UEs. The eNB includes a physical downlink shared channel (PDSCH) as a main physical channel for unicast transmission, downlink control information such as scheduling required for reception of a PDSCH, A physical downlink control channel (PDCCH) for transmitting scheduling grant information for transmission in a Physical Uplink Shared Channel (PUSCH). Hereinafter, the transmission / reception of a signal through each channel will be described in a form in which the corresponding channel is transmitted / received.

[ MTC What?]

Machine Type Communication (MTC) is defined as communication between a device and an object without human intervention. From the 3GPP perspective, "machine" means an entity that does not require direct manipulation or intervention by a person, and "MTC" is defined as a form of data communication involving one or more of these machines. A typical example of the machine is a smart meter equipped with a mobile communication module, a vending machine, etc. However, recently, a smart phone that performs communication by automatically connecting to a network without any user operation or intervention, The mobile terminal having the MTC function is considered as a type of machine.

[ LTE  Low-cost based MTC ]

As the LTE network spreads, mobile operators want to minimize the number of Radio Access Terminals (RATs) to reduce network maintenance costs. However, conventional MTC products based on a GSM / GPRS network are increasing, and MTC using a low data rate can be provided at low cost. Therefore, there is a problem in that two RATs must be operated respectively, since LTE network is used for general data transmission and GSM / GPRS network is used for MTC. Therefore, Of the total revenue.

In order to solve this problem, it is necessary to replace a cheap MTC terminal using a GSM / EGPRS network with an MTC terminal using an LTE network, and various requirements for lowering the price of the LTE MTC terminal are required for the 3GPP RAN WG1 standard conference . In addition, the standard meeting is preparing a document (TR 36.888) describing various functions that can be provided to satisfy the above requirements.

Major items related to the change of the physical layer standard currently under discussion in 3GPP in order to support the low-cost LTE MTC terminal include technologies such as narrow band support, Single RF chain, Half duplex FDD and Long DRX (Discontinued Reception). However, the above methods, which are considered for lowering the price, can reduce the performance of the MTC terminal as compared with the conventional LTE terminal.

In addition, about 20% of MTC terminals supporting MTC services such as smart metering are installed in a 'deep indoor' environment such as a basement. Therefore, for successful MTC data transmission, the coverage of LTE MTC terminals is compared with the coverage of conventional LTE terminals To be improved by about 15 [dB].

The following table shows the link budget of each physical channel as MCL (Maximum Coupling Loss) value. In case of FDD PUSCH, the MCL value is the smallest, so the target MCL value for improving 15 [dB] is 140.7 + 15 = 155.7 [dB].

The table below shows the degree of coverage improvement for each physical channel required to satisfy the target MCL value.

Various methods for robust transmission such as PSD boosting or low coding rate and time domain repetition are considered for each physical channel in order to improve the coverage while lowering the price of the LTE MTC terminal.

The requirements of low-cost MTC terminal based on LTE are as follows.

● The data transmission rate is the data transmission rate provided by the minimum EGPRS-based MTC terminal,

Link 118.4kbps, and uplink 59.2kbps.

● Frequency efficiency should be improved dramatically compared to GSM / EGPRS MTC terminal.

● The service area provided should not be less than that provided by the GSM / EGPRS MTC terminal.

● The power consumption should not be larger than the GSM / EGPRS MTC terminal.

● Legacy LTE terminals and LTE MTC terminals should be available at the same frequency.

● Reuse existing LTE / SAE networks.

● Optimization is performed not only in the FDD mode but also in the TDD mode.

● Low-cost LTE MTC terminals should support limited mobility and low power consumption modules.

The base station can allocate resources for up to six PRB pairs in one subframe for the MTC terminal, and the maximum available transport block size (TBS) is 1000 bits.

In the conventional LTE system, the base station can distinguish characteristics and types of terminals only after receiving the UE category and UE capability information RRC messages. Also, the base station receives CQI feedback composed of 4 bits to check the channel state from the UE prior to downlink data transmission to the UE. The base station schedules the transmission resource considering the channel state to the terminal with reference to the channel state. This is called channel-dependent scheduling. In the conventional LTE system, by using the CQI feedback, it is possible to check the level of geometry within the coverage of the base station.

In Table 3, CQI index '0' indicates that the UE has failed to receive the downlink signal from the BS or 'out of range' in which the channel is not good enough for the UE to operate. The spectral efficiency (or efficiency) in the LTE CQI table represents the amount of information bits transmitted per modulation symbol as a product of a code rate and a modulation order as a transmission efficiency. In addition, the spectral efficiency of CQI index 2 to 14 coincides with the spectral efficiency of the specific MCS index considered by the BS in data transmission, and the relationship is shown in Table 4 below.

FIG. 1 shows BLER performance for 15 spectral efficiencies used in the LTE CQI.

The base station can distinguish between the general LTE mobile station and the MTC mobile station using the UE category and UE capability information RRC message.

The MTC terminal operating at an improved coverage of 15 [dB] compared to a general LTE terminal requires a relatively large amount of transmission resources. The base station schedules transmission resources so that it can be repeatedly transmitted to a plurality of subframes for the coverage enhanced MTC terminal. However, when the conventional CQI table is used, the MTC terminal located in the enhanced coverage always feeds back the CQI index '0' times, that is, 'out of range', so that the base station can not perform channel- do. In other words, there is only one channel feedback for the extended coverage area, and the base station is required to operate at an improved coverage of 15 [dB] whenever the MTC terminal is out of coverage of the general LTE terminal regardless of the geometry of the MTC terminal To schedule many transmission resources.

The present invention proposes a method of constructing a CQI table for a MTC terminal so that a base station can check the geometry level of the MTC terminal for a coverage extended MTC terminal.

A method of configuring an MTC dedicated CQI table that can be used by the MTC terminal, including general LTE coverage and 15 [dB] extended coverage, will be described. First, in the conventional CQI table, a part of 15 CQI entries from CQI index 1 to 15 can be removed and a new CQI entry for extended coverage can be added.

The table below shows the MCS index, the modulation method, the TBS index, and the number of PRB pairs NBS TBS values used when _PRB is 1 to 6.

Considering that the maximum TBS value of the data channel used for the scheduling of the MTC mobile station is 1000 bits, the larger the number of PRB pairs, the smaller the maximum MCS index that the BS can use for scheduling. If N _PRB = 6, the base station can schedule the MTC terminal using only QPSK modulation. Therefore, it is preferable that all six CQI entries from CQI index 1 to 6 using QPSK modulation in the conventional CQI table are used as CQI entries for the MTC terminal.

Next, for the CQI entry between CQI index 7 and CQI index 15 corresponding to 16QAM and 64QAM modulation, the corresponding SNR for 10% BLER is equal to the CQI index 8, 10, 12 and 14 Gt; CQI < / RTI >

The following table shows the CQI index and CQI entry (modulation method, code rate and efficiency) that the MTC terminal transmits to the base station for channel feedback when its geometry is in the coverage of a general LTE terminal.

The MTC mobile station operating at 15 [dB] extended coverage instead of the four removed CQI entries may use CQI indices 1 to 4 for channel feedback to the base station. 15 [dB] Four new CQI entries for MTC terminal operating in extended coverage can be defined as follows.

In Table 4, the transmission efficiency of the MCS index 0 used for PDSCH data transmission is 0.2344, which is the same as the transmission efficiency of the CQI index 6 (Code rate = 120/1024, QPSK modulation) shown in Table 6. In Table 2, it can be seen that the coverage improvement of the PDSCH required for 15 [dB] coverage improvement of the MTC terminal is 10.3 [dB].

The SNR-to-SNR transmission efficiency can be configured as follows from the Capacity equation. Also, the transmission efficiency versus SNR value can be calculated by inverting the following equation.

[Equation 1]

Transmission efficiency [bps / Hz] = Capacity / BW = log ₂ (1 + 10 ^{SNR / 10} )

From the above equation, the transmission efficiency SNR for CQI index 6 in Table 6 is -7.5351 [dB]. Therefore, considering the 10.3 dB coverage improvement required for PDSCH, the SNR for CQI index 1 in Table 6 becomes -17.8351 [dB]. The CQI index is set so that the SNR interval from 1 to 6 is equally spaced as much as possible, and this value is calculated as the transmission efficiency value as shown in Table 7 below.

In Table 7, a value corresponding to a code rate * 1024 is a value calculated as efficiency * 1024/2. If the calculated code rate * 1024 value is rounded to represent a natural number as in the conventional CQI table, 8. In Table 8, the efficiency value corresponds to the code rate x 1024 expressed as a natural number. Here, in the case of the CQI index 5, the code rate * 1024 = 78 used in the conventional CQI table is reused rather than the calculated value in Table 7 above.

2 is a diagram illustrating a configuration of a base station according to another embodiment of the present invention.

2, the base station 1000 according to another embodiment includes a control unit 1010, a transmission unit 1020, and a reception unit 1030.

The controller 1010 controls the overall operation of the base station according to the CQI table configuration for the MTC terminal so that the base station can check the geometry level of the MTC terminal for the coverage extended MTC terminal required to perform the above- do.

The transmitting unit 1020 and the receiving unit 1030 are used to transmit and receive signals, messages, and data necessary for carrying out the present invention to and from the terminal.

3 is a diagram illustrating a configuration of a user terminal according to another embodiment of the present invention.

3, a user terminal 1100 according to another embodiment of the present invention includes a receiving unit 1110, a control unit 1120, and a transmitting unit 1130.

The receiving unit 1110 receives downlink control information, data, and messages from the base station through the corresponding channel.

In addition, the controller 1120 controls the overall operation of the terminal according to the CQI table configuration for the MTC terminal so that the base station can confirm the geometry level of the MTC terminal, with respect to the coverage extended MTC terminal required to perform the above- .

The transmitter 1130 transmits uplink control information, data, and a message to the base station through the corresponding channel.

The standard content or standard documents referred to in the above-mentioned embodiments constitute a part of this specification, for the sake of simplicity of description of the specification. Therefore, it is to be understood that the content of the above standard content and some of the standard documents is added to or contained in the scope of the present invention, as falling within the scope of the present invention.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims (1)

For the coverage extended MTC terminal, the MTC terminal uses the CQI table used by the MTC terminal, including the coverage and extended coverage of the general LTE terminal, so that the base station can check the geometry level of the MTC terminal, CQI feedback method.

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