Wireless communication device for calculating SNR using unused resource elements and method of operation thereof

Abstract

The present disclosure provides a wireless communication device that computes SNR using unused resource elements and a method of operating the same. An operation method of a wireless communication device operating in a narrowband Internet of Things (IoT) communication independent mode includes calculating a noise covariance of a target subframe among a plurality of subframes included in a downlink signal based on a signal received through an unused resource element in the target subframe, and the downlink signal is received from an external device; and estimating a signal-to-noise ratio of the target subframe based on the noise covariance.

Description

Technical Field

[0001] The inventive concept relates to a wireless communication apparatus for calculating a signal-to-noise ratio (SNR) by using unused resource elements. Background Art

[0002] Lower power and longer distance communication technology is used in the field of Internet of Things (IoT) and has been proposed to meet conditions such as lower power consumption, lower cost devices, lower establishment cost, stable coverage, and larger-scale device access. A typical example of lower power and longer distance communication technology is narrowband IoT communication technology, and narrowband IoT communication technology can provide stable communication services without establishing a separate network for IoT by using an already established existing long term evolution (LTE) network. Similarly, because narrowband IoT communication technology supports communication using a narrowband, it can also be used for satellite communication involving lower power and longer distance communication.

[0003] In narrowband IoT communications, SNR is a metric used for channel estimation performance improvement, scene recognition, etc., and improvements in the performance of wireless communication devices rely on accurate SNR estimation. In narrowband IoT communications, a narrowband reference signal (NRS) can be used as a noise sample to estimate the SNR. However, the number of noise samples obtained by NRS is not enough to ensure the accuracy of SNR estimation. Summary of the invention

[0004] The inventive concept provides a wireless communication device capable of more accurately estimating a signal-to-noise ratio (SNR) in narrowband Internet of Things (IoT) communications. An embodiment provides a method capable of accurately estimating an SNR.

[0005] According to one aspect of the inventive concept, there is provided an operating method of a wireless communication device operating in a narrowband IoT communication independent mode, the operating method comprising: calculating a noise covariance of a target subframe based on a signal received through unused resource elements in a target subframe among a plurality of subframes, the plurality of subframes being included in a downlink signal, and the downlink signal being received from an external device; and estimating a signal-to-noise ratio of the target subframe based on the noise covariance.

[0006] According to one aspect of the inventive concept, there is provided a wireless communication device operating in a narrowband IoT communication independent mode, the wireless communication device comprising: a processing circuit, the processing circuit being configured to: determine an unused resource element in a target subframe based on the type of the target subframe, the target subframe being included in a downlink signal received from an external device; and calculate a noise covariance of the target subframe based on a signal received through the unused resource element.

[0007] According to one aspect of the inventive concept, there is provided an operating method of a wireless communication device operating in a narrowband Internet of Things (IoT) communication independent mode, the operating method comprising: determining a type of a target subframe among a plurality of subframes, the plurality of subframes being included in a downlink signal received from an external device; determining unused resource elements in the target subframe based on the type of the target subframe; calculating a noise covariance of the target subframe based on a signal received through the unused resource elements; and estimating a signal-to-noise ratio of the target subframe based on the noise covariance. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Embodiments will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0009] Figure 1 is a diagram illustrating a wireless communication system according to an embodiment;

[0010] Figure 2 is a block diagram illustrating a wireless communication device according to an embodiment;

[0011] Figure 3 is a diagram illustrating a basic structure of a time-frequency domain as a wireless resource domain in a wireless communication system;

[0012] Figure 4 is a diagram illustrating a subframe configuration of a downlink signal received by a wireless communication device according to an embodiment;

[0013] Figure 5 is a diagram illustrating a resource grid of a received subframe of a first type according to an embodiment;

[0014] Figure 6 is a diagram illustrating a resource grid of a second type of subframe received by a wireless communication device according to an embodiment;

[0015] Figure 7 is a diagram illustrating a resource grid of a third type of subframe received by a wireless communication device according to an embodiment;

[0016] Figure 8 is a diagram illustrating a resource grid of a fourth type of subframe received by a wireless communication device according to an embodiment;

[0017] Fig. 9 is a flowchart illustrating an operation method of a wireless communication device according to an embodiment;

[0018] Fig.10 is a flow chart illustrating a specific method of calculating noise covariance by a wireless communication device according to an embodiment;

[0019] Fig.11 is a block diagram schematically illustrating an electronic device according to an embodiment; and

[0020] Fig.12 is a conceptual diagram illustrating an Internet of Things (IoT) network system according to an embodiment. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

[0022] Figure 1 is a diagram illustrating a wireless communication system according to an embodiment.

[0023] refer to Figure 1 , the wireless communication system 10 may include a cell 20 (or a serving cell) and / or a wireless communication device 30.

[0024] Hereinafter, an embodiment in which the wireless communication system 10 is based on narrowband Internet of Things (IoT) communication will be mainly described; however, the inventive concept is not limited thereto. In particular, the embodiment can be applied to various types of lower power longer distance communications with similar technical backgrounds. In addition, the embodiment can also be applied to other wireless communication systems (e.g., cellular communication systems such as wireless broadband (WiBro), global system for mobile communications (GSM), 5G and 6G, or short-range communication systems such as Bluetooth and near field communication (NFC)).

[0025] Similarly, the various functions described below can be implemented or supported by artificial intelligence technology or one or more computer programs, and each program may include a computer-readable program code, and may be implemented in a non-transitory computer-readable medium. The terms "application" and "program" may refer to one or more computer programs, software components, instruction sets, processes, functions, objects, classes, instances, related data, or parts thereof suitable for implementing suitable computer-readable program codes. The term "computer-readable program code" may include all types of computer codes, including source code, object code, and run code. The term "computer-readable medium" may refer to all types of computer-accessible media, such as read-only memory (ROM), random access memory (RAM), hard drive, compact disk (CD), digital video disk (DVD), or any other type of memory. "Non-transitory" computer-readable media may exclude wired, wireless, optical, or other communication links that send temporary electrical signals or other signals, and non-transitory computer-readable media may include media in which data may be permanently stored and media in which data may be stored and overwritten, such as rewritable optical disks or erasable memory devices.

[0026] In the following embodiments, a hardware method will be described as an example; however, since the embodiments include techniques using both hardware and software, the embodiments do not exclude a software-based method (eg, a method involving a combination of software and hardware).

[0027] The cell 20 may generally refer to a fixed station that communicates with the wireless communication device 30 or another base station (not shown). The cell 20 may exchange control information and data with the wireless communication device 30 or another cell by communicating with it. For example, the cell 20 may be referred to as a Node B, an evolved Node B (eNB), a next generation Node B (gNB), a sector, a site, a base transceiver system (BTS), an access point (AP), a relay node, a remote radio head (RRH), a radio unit (RU), a small cell, a wireless device, etc.

[0028] The wireless communication device 30 may be fixed or mobile. The wireless communication device 30 may refer to any device that transmits data and / or control information to / receives data and / or control information from the cell 20 by communicating with the cell 20. For example, the wireless communication device 30 may be referred to as a terminal, a terminal device, a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, a handheld device, etc.

[0029] The cell 20 may transmit a downlink signal DLS including a plurality of subframes to the wireless communication device 30 within its coverage 40. Herein, a subframe may refer to a data signal transmitted through a time-frequency resource corresponding to the subframe.

[0030] The wireless communication device 30 may receive a downlink signal DLS transmitted from the cell 20. The downlink signal DLS may include a plurality of subframes. Hereinafter, a target subframe may refer to a subframe selected as a target for signal-to-noise ratio (SNR) estimation among a plurality of subframes included in the downlink signal DLS, and a plurality of subframes may be sequentially selected as the target subframe.

[0031] The wireless communication device 30 can operate in an in-band mode of performing long-term evolution (LTE) communication and narrowband IoT communication simultaneously (or concurrently), and can operate in a narrowband IoT communication independent mode of performing only narrowband IoT communication without performing LTE communication (for example, a mode in which the wireless communication device 30 is performing narrowband IoT communication without performing LTE communication).

[0032] Hereinafter, an embodiment of a method for estimating SNR when the wireless communication device 30 operates in a narrowband IoT communication standalone mode will be mainly described; however, the inventive concept is not limited thereto. In particular, the embodiment can also be applied to a wireless communication device 30 having a similar technical background.

[0033] In an embodiment, when a downlink signal including a plurality of subframes is received from a cell 20, a wireless communication device 30 operating in a narrowband IoT communication independent mode can calculate a noise covariance of a target subframe based on a signal received through an unused resource element in a target subframe among the plurality of subframes, and estimate the SNR of the target subframe based on the noise covariance of the target subframe. Therefore, since the wireless communication device 30 according to the embodiment estimates the SNR based on a signal received through an unused resource element in a target subframe, the accuracy of the SNR estimation can be improved.

[0034] You can refer to Figure 2 and subsequent figures describe the specific structure and operating method of the wireless communication device 30.

[0035] Figure 2 is a block diagram illustrating a wireless communication device according to an embodiment.

[0036] refer to Figure 2 According to the embodiment, the wireless communication device 100 may include a plurality of antennas 101_1 to 101 — k, a transceiver 110 and / or a processor 120 .

[0037] The transceiver 110 may receive a downlink signal transmitted from an external device (e.g., a cell) through the antennas 101_1 to 101_k. The transceiver 110 may down-convert the received downlink signal to generate an intermediate frequency signal or a baseband signal. Similarly, the transceiver 110 may up-convert the intermediate frequency signal or the baseband signal output from the processor 120 and transmit the result as an uplink signal through the antennas 101_1 to 101_k.

[0038] The processor 120 may control the overall communication operation of the wireless communication device 100. The processor 120 may be implemented by a digital processing unit (NPU), a graphic processing unit (GPU), or the like.

[0039] The processor 120 can generate a data signal by filtering, decoding and digitizing the intermediate frequency signal or the baseband signal. The processor 120 can perform specific operations based on the data signal. Similarly, the processor 120 can encode, multiplex and infer the data signal generated by the specific operation.

[0040] The processor 120 may include an SNR estimation circuit 121. The SNR estimation circuit 121 may perform SNR estimation according to an embodiment. The operation of the SNR estimation circuit 121 described below may be understood as the operation of the processor 120. In particular, the SNR estimation circuit 121 may be implemented as hardware, or may be stored in a memory (not shown) in the form of a program code executed by the processor 120 to perform channel estimation according to an embodiment.

[0041] In an embodiment, when the wireless communication device 100 operates in the narrowband IoT communication standalone mode, the SNR estimation circuit 121 may calculate the noise covariance of the target subframe based on a signal received from an unused resource element in a target subframe among a plurality of subframes included in a downlink signal received from an external device through the transceiver 110. Next, the SNR estimation circuit 121 may estimate the SNR of the target subframe based on the noise covariance of the target subframe.

[0042] In particular, the SNR estimation circuit 121 may determine the type of the target subframe to calculate the noise covariance of the target subframe. The SNR estimation circuit 121 may determine the type of the target subframe included in the downlink signal based on the frame structure corresponding to the radio access technology used by the wireless communication device 100. In an embodiment, the wireless communication device 100 may use LTE as the radio access technology and refer to Figure 3 and Figure 4 A frame structure in a case where the radio access technology used by the wireless communication device 100 is LTE is described in detail.

[0043] Figure 3 The diagram illustrates a basic structure of a time-frequency domain as a wireless resource domain in a wireless communication system.

[0044] refer to Figure 3 , you can see the wireless resource domain used in the wireless communication system. Figure 3 In the wireless resource domain, the horizontal axis may represent the time domain, and the vertical axis may represent the frequency domain.

[0045] The lowest (or smallest) transmission unit in the time domain may be an orthogonal frequency division multiplexing (OFDM) symbol, and N symb OFDM symbols 202 may be grouped to form a slot 206. Likewise, two slots may be grouped to form a subframe 205. In an example, the length of the slot 206 may be 0.5 ms, and the length of the subframe 205 may be 1.0 ms. However, this is merely an example, and the length of the slot 206 may vary depending on the configuration of the slot 206, and the number of slots 206 included in the subframe 205 may vary depending on the length of the slot 206. Likewise, the frame 214 may be a time domain unit including 10 subframes 205.

[0046] The lowest (or smallest) transmission unit in the frequency domain may be a subcarrier, and the bandwidth of the entire system transmission band may include a total of N BW There are 204 subcarriers.

[0047] In the time-frequency domain, the basic unit of resources may be a resource element 212 and may be represented by an OFDM symbol index and a subcarrier index. A resource block 208 may be defined as N in the time domain. symb consecutive OFDM symbols 202 and N in the frequency domain RB contiguous subcarriers 210. Thus, resource block 208 may include (N symb ×N RB ) resource elements 212. A resource block pair may be a unit of two RBs concatenated on a time axis and may include (N symb ×2N RB ) resource elements 212.

[0048] Figure 3 The basic structure in the time-frequency domain shown can be used in narrowband IoT communication according to an embodiment.

[0049] Figure 4 is a diagram illustrating a subframe configuration of a downlink signal received by a wireless communication device according to an embodiment.

[0050] refer to Figure 4 , it can be seen that the frame structure of the downlink signal received by the wireless communication device when the wireless access technology is LTE. However, the inventive concept is not limited thereto, and the frame structure can follow the narrowband IoT related standard specification of the third generation partnership project (3GPP) version.

[0051] exist Figure 4 In the example of , the frame structure may include a first frame and a second frame, and each frame may include 10 subframes. The 10 subframes included in the first frame may have indexes of 0 to 9 in time order, and the 10 subframes included in the second frame may have indexes of 10 to 19 in time order. In this case, the downlink signal received by the wireless communication device may have an index such as Figure 4 The form of the repetitive frame structure shown.

[0052] exist Figure 4 In an embodiment of the present invention, the multiple subframes included in the frame structure may be of any one of the first type to the fourth type.

[0053] The first type may be a subframe including a narrowband physical broadcast channel (NPBCH) resource element, and Figure 4 In the example of , NPBCH elements can be arranged in subframes with subframe indices 0 and 10.

[0054] The second type may be a subframe including a narrowband primary synchronization signal (NPSS) resource element, and Figure 4 In the example of , NPSS resource elements can be arranged in subframes with subframe indices 5 and 15.

[0055] The third type may be a subframe including a narrowband secondary synchronization signal (NSSS) resource element, and Figure 4 In the example, the NSSS resource elements can be arranged in a subframe with a subframe index of 9.

[0056] The fourth type may be a subframe including a narrowband physical downlink control channel (NPDCCH) resource element or a narrowband physical downlink shared channel (NPDSCH) resource element, and Figure 4 In the example of FIG. 1 , NPDCCH resource elements and / or NPDSCH resource elements may be arranged in subframes with subframe indices of 1 to 4, 6 to 8, 11 to 14, and 16 to 19 (for clarity of illustration, from Figure 4 The depiction of these elements is omitted).

[0057] Return to reference Figure 2 , based on Figure 4 In the frame structure in the example of , the SNR estimation circuit 121 can determine the type of the target subframe included in the downlink signal based on which subframes have been previously received.

[0058] In an embodiment, the type of the target subframe may be as described above with reference to Figure 4 Any one of the first to fourth types described. In this case, the first type of target subframe may include an NPBCH resource element, the second type of target subframe may include an NPSS resource element, the third type of target subframe may include an NSSS resource element, and the fourth type of target subframe may include an NPDCCH resource element or an NPDSCH resource element. According to an embodiment, each of the first to fourth types of target subframes may correspond to a wireless access technology (e.g., narrowband IoT communication) used by a wireless communication device.

[0059] After determining the type of the target subframe, the SNR estimation circuit 121 may determine the unused resource elements in the target subframe based on the type of the target subframe. The SNR estimation circuit 121 may determine the unused resource elements in the target subframe based on the resource grid corresponding to the type of the target subframe. An example of a resource grid in a corresponding case where the type of the target subframe is the first type to the fourth type may be as follows Figures 5 to 8 As shown.

[0060] Figure 5 is a diagram illustrating a resource grid of a received subframe of a first type according to an embodiment.

[0061] refer to Figure 5, it can be seen that when the wireless communication device 100 operates in the narrowband IoT communication independent mode, the type of the subframe of the downlink signal is the resource grid of the first type. Figure 5 In a resource grid of FIG. 1 , the horizontal axis may represent a symbol index and the vertical axis may represent a subcarrier index.

[0062] exist Figure 5 In the example of , the resource elements marked with P0 in the resource elements may refer to the first narrowband reference signal resource elements sent by the first transmission port used in the narrowband IoT communication. The resource elements marked with P1 in the resource elements may refer to the second narrowband reference signal resource elements sent by the second transmission port used in the narrowband IoT communication. The resource elements marked with X in the resource elements may refer to unused resource elements. The resource elements without marks in the resource elements may refer to NPBCH resource elements.

[0063] In this case, since the narrowband reference signal is transmitted through the first narrowband reference signal resource element and the second narrowband reference signal resource element for narrowband IoT communication, the wireless communication device 100 can receive the signal including noise in the narrowband reference signal through the first narrowband reference signal resource element and the second narrowband reference signal resource element. Therefore, when the target subframe is of the first type, the wireless communication device 100 can calculate the noise covariance using the signal received through the narrowband reference signal resource element.

[0064] According to an embodiment, as used herein, the term "unused resource element" may refer to a resource element of a subframe through which a signal (e.g., a data signal such as NPBCH, NPSS, NSSS, NPDCCH, NPDSCH, etc.) is not transmitted (e.g., by an external device). Since a signal is not transmitted through the unused resource elements included in the subframe, the wireless communication device 100 may receive a signal including only noise through the unused resource elements. Therefore, when the target subframe has a first type, the wireless communication device 100 may calculate the noise covariance using a signal received through the unused resource elements.

[0065] As described below, when the type of the target subframe is the first type in the narrowband IoT communication independent mode, the wireless communication device 100 according to an embodiment can use both the signal received through the narrowband reference signal resource element and the signal received through the unused resource element to calculate the noise covariance, so that the accuracy of the SNR estimation can be improved.

[0066] Figure 6 is a diagram illustrating a resource grid of a second type of subframe received by a wireless communication device according to an embodiment.

[0067] refer to Figure 6, it can be seen that when the wireless communication device 100 operates in the narrowband IoT communication independent mode, the type of the subframe of the downlink signal is the resource grid of the second type. Figure 6 In a resource grid of FIG. 1 , the horizontal axis may represent a symbol index and the vertical axis may represent a subcarrier index.

[0068] exist Figure 6 In the example of , resource elements marked with X in the resource elements may refer to unused resource elements. Resource elements without a mark in the resource elements may refer to NPSS resource elements.

[0069] In this case, since the signal is not transmitted through the unused resource elements included in the subframe, the wireless communication device 100 can receive a signal including only noise through the unused resource elements. Therefore, when the target subframe has the second type, the wireless communication device 100 can calculate the noise covariance using the signal received through the unused resource elements.

[0070] As described below, when the type of the target subframe is the second type in the narrowband IoT communication independent mode, the wireless communication device 100 according to the embodiment can use the signal received through the unused resource elements to calculate the noise covariance, so that the SNR can be estimated even in the subframe in which the narrowband reference signal is not received.

[0071] Figure 7 is a diagram illustrating a resource grid of a third type of subframe received by a wireless communication device according to an embodiment.

[0072] refer to Figure 7 , it can be seen that when the wireless communication device 100 operates in the narrowband IoT communication independent mode, the type of the subframe of the downlink signal is the resource grid of the third type. Figure 7 In a resource grid of FIG. 1 , the horizontal axis may represent a symbol index and the vertical axis may represent a subcarrier index.

[0073] exist Figure 7 In the example of , resource elements marked with X in the resource elements may refer to unused resource elements. Resource elements without a mark in the resource elements may refer to NSSS resource elements.

[0074] In this case, since the signal is not transmitted through the unused resource elements included in the subframe, the wireless communication device 100 can receive a signal including only noise through the unused resource elements. Therefore, when the target subframe is of the third type, the wireless communication device 100 can calculate the noise covariance using the signal received through the unused resource elements.

[0075] As described below, when the type of the target subframe is the third type in the narrowband IoT communication independent mode, the wireless communication device 100 according to the embodiment can use the signal received through the unused resource elements to calculate the noise covariance, so that the SNR can be estimated even in the subframe in which the narrowband reference signal is not received.

[0076] Figure 8 is a diagram illustrating a resource grid of a fourth type of subframe received by a wireless communication device according to an embodiment.

[0077] refer to Figure 8 , it can be seen that when the wireless communication device 100 operates in the narrowband IoT communication independent mode, the type of the subframe of the downlink signal is the resource grid of the fourth type. Figure 8 In a resource grid of FIG. 1 , the horizontal axis may represent a symbol index and the vertical axis may represent a subcarrier index.

[0078] exist Figure 8 In the example, the resource elements marked with P0 in the resource elements may refer to the first narrowband reference signal resource elements sent by the first transmission port used in the narrowband IoT communication. The resource elements marked with P1 in the resource elements may refer to the second narrowband reference signal resource elements sent by the second transmission port used in the narrowband IoT communication. The resource elements without marking in the resource elements may refer to NPDCCH resource elements or NPDSCH resource elements.

[0079] In this case, since the narrowband reference signal is transmitted through the first narrowband reference signal resource element and the second narrowband reference signal resource element for narrowband IoT communication, the wireless communication device 100 can receive a signal including noise in the narrowband reference signal through the first narrowband reference signal resource element and the second narrowband reference signal resource element. Therefore, when the target subframe has the fourth type, the wireless communication device 100 can calculate the noise covariance using the signal received through the narrowband reference signal resource element.

[0080] refer to Figures 5 to 8 The structure of the resource grid according to the type of the above subframe is only an example, and the inventive concept is not limited thereto, and the structure of the resource grid according to the type of the subframe can follow the narrowband IoT related standard specifications of the 3GPP version. According to an embodiment, the SNR estimation circuit 121 can be as described in relation to Figures 5 to 8 As discussed, the type of the target subframe is determined from the first to fourth types by detecting one or more of the above-mentioned resource elements (e.g., NPBCH resource elements, NPSS resource elements, NSSS resource elements, NPDCCH resource elements and / or NPDSCH resource elements) at a position corresponding to one of the first to fourth types of the subframe in the resource grid.

[0081] Similarly, an embodiment will be mainly described in which both the first transmission port and the second transmission port are used in narrowband IoT communication so that a narrowband reference signal is received through the first narrowband reference signal resource element and the second narrowband reference signal resource element; however, the inventive concept is not limited to this, and the example can be modified and applied to an embodiment in which only one of the first transmission port and / or the second transmission port is used.

[0082] Return to reference Figure 2 After determining the unused resource elements in the target subframe, the SNR estimation circuit 121 may calculate the noise covariance of the target subframe based on the signals received through the unused resource elements in the target subframe.

[0083] The SNR estimation circuit 121 may calculate the noise covariance of the target subframe by using the following equation.

[0084] First, a signal received by the transceiver 110 of the wireless communication device 100 may be generally expressed as Equation 1 below.

[0085] [Formula 1]

[0086] y=Hx+n

[0087] In Formula 1, “y” may represent a reception signal received by the transceiver 110 , “x” may represent a transmission signal transmitted by an external device, “H” may represent a channel value through which the transmission signal passes, and “n” may represent a noise signal.

[0088] The noise covariance can be generally calculated as in Equation 2 below.

[0089] [Formula 2]

[0090] R = E{nn H}

[0091] In Formula 2, “R” may represent noise covariance.

[0092] Since the SNR estimation circuit 121 uses the channel estimation value as the channel value through which the transmission signal passes, the noise covariance can be calculated as in the following Equation 3.

[0093] [Formula 3]

[0094]

[0095] In formula 3, can represent the channel estimate, and The noise covariance calculated based on the channel estimation value may be represented.

[0096] In this case, when the type of the target subframe is the first type, since the target subframe includes narrowband reference signal resource elements (including first narrowband reference signal resource elements and second narrowband reference signal resource elements) and unused resource elements, the noise covariance can be calculated as in the following Formula 4.

[0097] [Formula 4]

[0098]

[0099] In formula 4, may represent a narrowband reference signal noise covariance as a noise covariance calculated based on a signal received through a narrowband reference signal resource element in a target subframe, and The unused noise covariance may be expressed as a noise covariance calculated based on a channel estimation value and a signal received through an unused resource element in a target subframe.

[0100] In this case, it can be calculated as in the following formula 5

[0101] [Formula 5]

[0102]

[0103] In formula 5, Ω NRS It can represent a set of narrowband reference signal resource elements included in the target subframe, |Ω NRS | may represent the total number of narrowband reference signal resource elements included in the target subframe, "k" may represent the symbol index of the narrowband reference signal resource element included in the target subframe, and "l" may represent the subcarrier index of the narrowband reference signal resource element included in the target subframe. In this case, "x" may represent a narrowband reference signal transmitted by an external device, and a reference signal sequence pre-calculated (or given or calculated) by the SNR estimation circuit 121 may be used as the narrowband reference signal "x" transmitted by the external device. According to an embodiment, the channel estimation value It can be calculated based on the signal received through the narrowband reference signal resource element in the target subframe. For example, the channel estimation value can be calculated based on the noise obtained by performing an inverse fast Fourier transform (IFFT) on the signal received through the narrowband reference signal resource element and filtering the main part of the time domain signal obtained by IFFT.

[0104] Since the transmission signal transmitted through the unused resource element is 0 and the received signal is the same as (or similar to) the noise signal, it can be calculated as in the following formula 6

[0105] [Formula 6]

[0106]

[0107] In formula 6, Ω NUS It can represent a set of unused resource elements included in the target subframe, |Ω NUS | may represent the total number of unused resource elements included in the target subframe, “k” may represent the symbol index of the unused resource elements included in the target subframe, and “l” may represent the subcarrier index of the unused resource elements included in the target subframe.

[0108] By using the above equation, the SNR estimation circuit 121 may calculate the noise covariance of the target subframe based on the signal received through the resource element according to the type of the target subframe.

[0109] In an embodiment, when the type of the target subframe is the first type, the SNR estimation circuit 121 may calculate the noise covariance of the target subframe based on signals received through unused resource elements in the target subframe and signals received through narrowband reference signal resource elements in the target subframe.

[0110] In particular, when the type of the target subframe is the first type, the target subframe may include narrowband reference signal resource elements and unused resource elements.

[0111] The SNR estimation circuit 121 may calculate the unused noise covariance based on the signal received through the unused resource element in the target subframe. In this case, the SNR estimation circuit 121 may calculate the unused noise covariance by using Formula 6. According to an embodiment, the SNR estimation circuit 121 may calculate the unused noise covariance based on the signal received through the unused resource element in response to determining that the target subframe includes the unused resource element (e.g., in response to determining that the target subframe is of the first type, the second type, or the third type).

[0112] Similarly, the SNR estimation circuit 121 can calculate the narrowband reference signal noise covariance based on a pre-calculated (or alternatively, given or calculated) reference signal sequence and a channel estimate calculated based on a signal received through a narrowband reference signal resource element in a target subframe. Here, the channel estimate can be calculated based on the noise obtained by performing an inverse fast Fourier transform (IFFT) on the signal received through the narrowband reference signal resource element and filtering the main part of the time domain signal obtained by the IFFT. In this case, the SNR estimation circuit 121 can calculate the narrowband reference signal noise covariance by using Formula 5. According to an embodiment, the SNR estimation circuit 121 can calculate the narrowband reference signal noise covariance based on the signal received through the narrowband reference signal resource element in response to determining that the target subframe includes a narrowband reference signal resource element (for example, in response to determining that the target subframe is a first type or a fourth type).

[0113] Next, the SNR estimation circuit 121 may calculate the noise covariance by adding the unused noise covariance and the narrowband reference signal noise covariance. That is, the SNR estimation circuit 121 may calculate the unused noise covariance by using Formula 4. According to an embodiment, the SNR estimation circuit 121 may calculate the noise covariance by adding the unused noise covariance and the narrowband reference signal noise covariance in response to determining that the target subframe is of the first type.

[0114] In an embodiment, when the type of the target subframe is the second type or the third type, the SNR estimation circuit 121 may calculate the noise covariance of the target subframe based on a signal received through unused resource elements in the target subframe.

[0115] In particular, when the type of the target subframe is the second type or the third type, the target subframe may include unused resource elements.

[0116] The SNR estimation circuit 121 may calculate the unused noise covariance based on the signal received through the unused resource element in the target subframe. In this case, the SNR estimation circuit 121 may calculate the unused noise covariance by using Formula 6. According to an embodiment, the SNR estimation circuit 121 may calculate the unused noise covariance based on the signal received through the unused resource element in response to determining that the target subframe includes the unused resource element (e.g., in response to determining that the target subframe is of the first type, the second type, or the third type).

[0117] In this case, because the target subframe does not include a narrowband reference signal resource element, the SNR estimation circuit 121 may use the unused noise covariance as the noise covariance. According to an embodiment, the SNR estimation circuit 121 may use the unused noise covariance as the noise covariance in response to determining that the target subframe is of the second type or the third type.

[0118] In an embodiment, when the type of the target subframe is the fourth type, the SNR estimation circuit 121 may calculate the noise covariance of the target subframe based on a signal received through a narrowband reference signal resource element in the target subframe.

[0119] In particular, when the type of the target subframe is the fourth type, the target subframe may include a narrowband reference signal resource element. According to an embodiment, the SNR estimation circuit 121 may calculate the narrowband reference signal noise covariance based on a signal received through the narrowband reference signal resource element in response to determining that the target subframe includes a narrowband reference signal resource element (e.g., in response to determining that the target subframe is the first type or the fourth type).

[0120] The SNR estimation circuit 121 can calculate the narrowband reference signal noise covariance based on a pre-calculated (or alternatively, a given or calculated) reference signal sequence and a channel estimation value calculated based on a signal received by a narrowband reference signal resource element in a target subframe. In this case, the SNR estimation circuit 121 can calculate the narrowband reference signal noise covariance by using Formula 5.

[0121] In this case, because the target subframe does not include unused resource elements, the SNR estimation circuit 121 may use the narrowband reference signal noise covariance as the noise covariance. According to an embodiment, the SNR estimation circuit 121 may use the narrowband reference signal noise covariance as the noise covariance in response to determining that the target subframe is of the second type or the fourth type.

[0122] Next, the SNR estimation circuit 121 may estimate the SNR of the target subframe based on the noise covariance of the target subframe. In this case, the SNR estimation circuit 121 may estimate the SNR of the target subframe by calculating the SNR based on the noise covariance using a known general SNR calculation method.

[0123] The processor 120 may perform various types of subsequent operations based on the SNR of the target subframe estimated by the SNR estimation circuit 121. In an embodiment, the processor 120 may perform symbol detection of the target subframe (e.g., to detect a symbol transmitted by an external device via the target subframe) based on the SNR of the target subframe estimated by the SNR estimation circuit 121. Similarly, in an embodiment, the processor 120 may perform channel estimation of the target subframe (e.g., to estimate a channel between the wireless communication device 100 and the external device through which the target subframe is received by the wireless communication device 100) based on the SNR of the target subframe estimated by the SNR estimation circuit 121.

[0124] By using the wireless communication device 100 according to the embodiment described above, the accuracy of SNR estimation can be improved by calculating the noise covariance using both the signal received through the narrowband reference signal resource element and the signal received through the unused resource element. Similarly, by calculating the noise covariance using the signal received through the unused resource element, the SNR can be estimated even in a subframe in which a narrowband reference signal is not received. Similarly, as described above, by improving the accuracy of SNR estimation and performing SNR estimation under various environments, the performance of subsequent operations such as symbol detection and channel estimation performed based on the SNR can be improved.

[0125] Fig. 9 is a flowchart illustrating an operation method of a wireless communication device according to an embodiment.

[0126] refer to Fig. 9 , in operation S910, the wireless communication device 100 may receive a downlink signal.

[0127] The wireless communication device 100 may receive a downlink signal including a plurality of subframes from an external device through the transceiver 110 .

[0128] In operation S920, the wireless communication device 100 may calculate a noise covariance of a target subframe.

[0129] The wireless communication device 100 can calculate the noise covariance of the target subframe based on the signal received through the unused resource elements in the target subframe among the multiple subframes through the processor 120. Fig.10 A specific method of calculating the noise covariance of the target subframe is described in detail.

[0130] Fig.10 is a flow chart illustrating a specific method of calculating noise covariance by a wireless communication device according to an embodiment.

[0131] refer to Fig.10 , in operation S1010, the wireless communication device 100 may determine the type of a target subframe.

[0132] The wireless communication device 100 may determine the type of the target subframe included in the downlink signal based on the frame structure corresponding to the radio access technology used by the wireless communication device 100 through the processor 120. The wireless communication device 100 may determine the type of the target subframe to be one of the first to fourth types.

[0133] In operation S1020, the wireless communication apparatus 100 may determine unused resource elements in a target subframe.

[0134] The wireless communication device 100 may determine, through the processor 120 , unused resource elements in the target subframe based on a resource grid corresponding to the type of the target subframe.

[0135] When the type of the target subframe is the first type, the wireless communication device 100 may Figure 5 The resource grid shown in the figure determines the unused resource elements in the target subframe. When the type of the target subframe is the second type, the wireless communication device 100 may determine the unused resource elements in the target subframe based on Figure 6 The illustrated resource grid determines the unused resource elements in the target subframe. When the type of the target subframe is the third type, the wireless communication device 100 may determine the unused resource elements in the target subframe based on Figure 7 The resource grid shown in the figure determines the unused resource elements in the target subframe. When the type of the target subframe is the fourth type, the wireless communication device 100 may determine the unused resource elements in the target subframe based on Figure 8 The illustrated resource grid determines unused resource elements in the target subframe (eg, it may be determined that the target subframe does not include unused resource elements).

[0136] In operation S1030 , the wireless communication device 100 may calculate a noise covariance of the target subframe.

[0137] The wireless communication device 100 may calculate, through the processor 120 , the noise covariance of the target subframe based on the signal received through the unused resource elements in the target subframe determined in operation S1020 .

[0138] When the type of the target subframe is the first type, the wireless communication device 100 may calculate the noise covariance of the target subframe based on the signal received through the unused resource element in the target subframe and the signal received through the narrowband reference signal resource element in the target subframe. In this case, the wireless communication device 100 may calculate the noise covariance of the target subframe by using Equations 4 to 6.

[0139] When the type of the target subframe is the second type or the third type, the wireless communication device 100 may calculate the noise covariance of the target subframe based on the signal received through the unused resource elements in the target subframe. In this case, the wireless communication device 100 may calculate the noise covariance of the target subframe by using Equation 6.

[0140] When the type of the target subframe is the fourth type, the wireless communication device 100 may calculate the noise covariance of the target subframe based on the signal received through the narrowband reference signal resource element in the target subframe. In this case, the wireless communication device 100 may calculate the noise covariance of the target subframe by using Equation 5.

[0141] Return to reference Fig. 9In operation S930, the wireless communication device 100 may estimate the SNR of the target subframe. The wireless communication device 100 may estimate the SNR of the target subframe by using the noise covariance calculated in operation S920 through the processor 120.

[0142] By using the operating method of the wireless communication device 100 according to the embodiment described above, the accuracy of SNR estimation can be improved by calculating the noise covariance using both the signal received through the narrowband reference signal resource elements and the signal received through the unused resource elements.

[0143] Fig.11 is a block diagram schematically illustrating an electronic device according to an embodiment.

[0144] refer to Fig.11 , the electronic device 1000 may include a memory 1010, a processor unit 1020, an input / output controller 1040, a display 1050, an input device 1060, and / or a communication processor 1090. Here, the memory 1010 may be provided as a plurality of memories. Each component thereof will be described below.

[0145] The memory 1010 may include a program storage device 1011 storing a program for controlling the operation of the electronic device 1000 and a data storage device 1012 storing data generated during the execution of the program. The data storage device 1012 may store data used for the operation of the application program 1013 and the SNR estimation program 1014, or may store data generated from the operation of the application program 1013 and the SNR estimation program 1014.

[0146] The program storage device 1011 may include an application program 1013 and an SNR estimation program 1014. Here, each program included in the program storage device 1011 may be a collection of instructions and may be represented as an instruction set. The application program 1013 may include program codes for running various applications working in the electronic device 1000. That is, the application program 1013 may include codes (or commands) related to various applications driven by the processor 1022.

[0147] According to an embodiment, when a downlink signal including multiple subframes is received while operating in a narrowband IoT communication independent mode, the SNR estimation program 1014 can calculate the noise covariance of the target subframe based on the signal received through the unused resource elements in the target subframe among the multiple subframes, and estimate the SNR of the target subframe based on the noise covariance of the target subframe.

[0148] In addition, the electronic device 1000 may include a communication processor 1090 that performs a communication function for voice communication and data communication. The peripheral device interface 1023 may control the connection between the input / output controller 1040, the communication processor 1090, the processor 1022, and / or the memory interface 1021. By using at least one software program, the processor 1022 may control a plurality of base stations to provide corresponding services. In this case, the processor 1022 may run at least one program stored in the memory 1010 and provide a service corresponding to the program.

[0149] The input / output controller 1040 may provide an interface between the peripheral device interface 1023 and input / output devices such as a display 1050 and an input device 1060. The display 1050 may display status information, input text, moving pictures, still pictures, etc. For example, the display 1050 may display application information driven by the processor 1022.

[0150] The input device 1060 may provide input data generated by the electronic device 1000 through selection to the processor unit 1020 through the input / output controller 1040. In this case, the input device 1060 may include a key area having at least one hardware button and a touch pad for sensing touch information. For example, the input device 1060 may provide touch information such as touch, touch movement, and touch release sensed through the touch pad to the processor 1022 through the input / output controller 1040.

[0151] Fig.12 is a conceptual diagram illustrating an IoT network system according to an embodiment.

[0152] refer to Fig.12 , the IoT network system 2000 may include a plurality of IoT devices 2100, 2120, 2140 and / or 2160, an access point 2200, a gateway 2250, a wireless network 2300 and / or a server 2400. IoT may refer to a network between things using wired / wireless communication.

[0153] Each of the IoT devices 2100, 2120, 2140, and 2160 may form a group according to the characteristics of each IoT device. For example, the IoT devices 2100, 2120, 2140, and 2160 may be grouped into a home gadget group 2100, a home appliance / furniture group 2120, an entertainment group 2140, a vehicle group 2160, and the like. A plurality of IoT devices 2100, 2120, and 2140 may be connected to a communication network or to another IoT device via an access point 2200. The access point 2200 may be built into one IoT device. The gateway 2250 may change the protocol to connect the access point 2200 to an external wireless network. The IoT devices 2100, 2120, and 2140 may be connected to an external communication network via the gateway 2250. The wireless network 2300 may include the Internet and / or a public network. The plurality of IoT devices 2100 , 2120 , 2140 , and 2160 may be connected to a server 2400 providing a specific service through a wireless network 2300 , and a user may use the service through at least one of the plurality of IoT devices 2100 , 2120 , 2140 , and 2160 .

[0154] According to an embodiment, a plurality of IoT devices 2100, 2120, 2140, and 2160 may perform narrowband IoT communication, and therefore, when a downlink signal including a plurality of subframes is received while operating in a narrowband IoT communication standalone mode, each of the IoT devices 2100, 2120, 2140, and 2160 may calculate a noise covariance of a target subframe based on a signal received through an unused resource element in a target subframe among the plurality of subframes, and estimate the SNR of the target subframe based on the noise covariance of the target subframe. Therefore, since the IoT devices 2100, 2120, 2140, and 2160 estimate the SNR based on a signal received through an unused resource element in the target subframe, the accuracy of the SNR estimation may be improved.

[0155] Existing devices and methods for calculating the noise covariance of a subframe in narrowband IoT communication rely on narrowband reference signals as noise samples. However, such narrowband reference signals do not provide a sufficient amount of noise samples (e.g., due to an insufficient amount of narrowband reference signals) to accurately calculate the noise covariance. Therefore, existing devices and methods are unable to estimate the signal-to-noise ratio (SNR) of a subframe in narrowband IoT communication accurately enough, which also leads to insufficient accuracy of operations performed based on the estimated SNR (such as symbol detection and channel estimation).

[0156] However, embodiments provide improved devices and methods for calculating the noise covariance of a subframe in narrowband IoT communications. For example, these improved devices and methods can utilize unused resource elements in a target subframe as noise samples when calculating the noise covariance in the target subframe. Therefore, in a target subframe having both a narrowband reference signal and unused resource elements, due to the increased number of noise samples, these improved devices and methods can more accurately calculate the noise covariance of the target subframe. Similarly, in a target subframe having unused resource elements but no narrowband reference signal, these improved devices and methods can accurately calculate the noise covariance of the target subframe in scenarios where existing devices and methods would not be able to calculate the noise covariance. Therefore, these improved devices and methods overcome the defects of conventional devices and methods to improve the accuracy of the calculated noise covariance, thereby improving the accuracy of the SNR estimated using the calculated noise covariance and improving the accuracy of operations performed based on the estimated SNR (such as symbol detection and channel estimation).

[0157] According to an embodiment, operations described herein as being performed by the wireless communication system 10, the cell 20, the wireless communication device 30, the wireless communication device 100, the transceiver 110, the processor 120, the SNR estimation circuit 121, the electronic device 1000, the processor unit 1020, the input / output controller 1040, the communication processor 1090, the application 1013, the SNR estimation program 1014, the peripheral device interface 1023, the processor 1022, the memory interface 1021, the IoT network system 2000, each among the plurality of IoT devices 2100, 2120, 2140 and / or 2160, the access point 2200, the gateway 2250 and / or the server 2400 may be performed by a processing circuit. As used in the present disclosure, the term "processing circuit" may refer to, for example, hardware including a logic circuit; a hardware / software combination such as a processor running software; or a combination thereof. For example, the processing circuit may more specifically include, but is not limited to, a central processing unit (CPU), an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA), a system on a chip (SoC), a programmable logic unit, a microprocessor, an application specific integrated circuit (ASIC), etc.

[0158] The various operations of the above methods may be performed by any suitable device capable of performing the operations (such as the processing circuits discussed above). For example, as discussed above, the operations of the above methods may be performed by various hardware and / or software implemented in some form of hardware (e.g., processor, ASIC, etc.).

[0159] Software may include an ordered listing of executable instructions for implementing logical functions and may be embodied in any "processor readable medium" for use by or in conjunction with an instruction execution system, device or apparatus (such as a single-core or multi-core processor or a system containing a processor).

[0160] The blocks or operations of the methods or algorithms and functions described in conjunction with the embodiments disclosed herein may be embodied in hardware, in software modules executed by a processor, or in a combination of the two. If implemented in software, the functions may be stored as one or more instructions or codes on a tangible non-transitory computer-readable medium (memory 1010) or sent thereon. The software module may reside in a random access memory (RAM), a flash memory, a read-only memory (ROM), an electrically programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a register, a hard disk, a removable disk, a CD ROM, or any other form of storage medium known in the art.

[0161] While the inventive concept has been particularly shown and described with reference to embodiments thereof, it will be understood that various changes in form and details may be made therein without departing from the spirit and scope of the appended claims.

Claims

1. A method for operating a wireless communication device operating in a narrowband Internet of Things communication independent mode, the method comprising: calculating a noise covariance of a target subframe based on a signal received through an unused resource element in a target subframe among a plurality of subframes, the plurality of subframes being included in a downlink signal, and the downlink signal being received from an external device; as well as A signal-to-noise ratio of the target subframe is estimated based on the noise covariance.

2. The operating method according to claim 1, wherein: Calculating the noise covariance includes: determining a type of the target subframe; and The unused resource elements are determined based on a type of the target subframe.

3. The operating method according to claim 2, wherein: Determining the type of the target subframe includes determining the type of the target subframe based on a frame structure corresponding to a radio access technology used by the wireless communication device.

4. The operating method according to claim 3, wherein: The type of the target subframe is one of the following: The target subframe includes a first type of narrowband physical broadcast channel resource elements; The target subframe includes a second type of narrowband primary synchronization signal resource element; The target subframe includes a third type of narrowband secondary synchronization signal resource element; and The target subframe includes a fourth type of narrowband physical downlink control channel resource elements or narrowband physical downlink shared channel resource elements.

5. The operating method according to claim 2, wherein: Determining the unused resource elements includes determining the unused resource elements based on a resource grid corresponding to a type of the target subframe.

6. The operating method according to claim 2, wherein: Calculating the noise covariance further includes calculating the noise covariance based on signals received through the unused resource elements and signals received through narrowband reference signal resource elements in the target subframe.

7. The operating method according to claim 6, wherein: Calculating the noise covariance further includes: calculating an unused noise covariance based on signals received through the unused resource elements; calculating a narrowband reference signal noise covariance based on a reference signal sequence and a channel estimation value calculated based on a signal received through the narrowband reference signal resource element; and The noise covariance is calculated by adding the unused noise covariance and the narrowband reference signal noise covariance.

8. The operating method according to claim 2, wherein: Calculating the noise covariance further includes: in response to determining that the target subframe is of a type including the unused resource element, calculating the noise covariance based on a signal received through the unused resource element.

9. The operating method according to claim 2, further comprising: Channel estimation is performed on the target subframe based on the signal-to-noise ratio.

10. The operating method according to claim 1, further comprising: Symbol detection of the target subframe is performed based on the signal-to-noise ratio.

11. A wireless communication device operating in a narrowband Internet of Things communication standalone mode, the wireless communication device comprising a processing circuit, the processing circuit being configured to: determining unused resource elements in a target subframe based on a type of the target subframe, the target subframe being included in a downlink signal received from an external device; and A noise covariance of the target subframe is calculated based on signals received through the unused resource elements.

12. The wireless communication device according to claim 11, wherein: The processing circuit is further configured to determine the type of the target subframe based on a frame structure corresponding to a radio access technology used by the wireless communication device.

13. The wireless communication device according to claim 11, wherein: The processing circuit is further configured to determine the unused resource elements based on a resource grid corresponding to a type of the target subframe.

14. The wireless communication device according to claim 11, wherein: The processing circuit is further configured to calculate the noise covariance based on signals received through the unused resource elements and signals received through narrowband reference signal resource elements in the target subframe.

15. The wireless communication device according to claim 14, wherein: The processing circuit is further configured to: calculating an unused noise covariance based on signals received through the unused resource elements; Calculating a narrowband reference signal noise covariance based on a reference signal sequence and a channel estimate value calculated based on a signal received through the narrowband reference signal resource element; as well as The noise covariance is calculated by adding the unused noise covariance and the narrowband reference signal noise covariance.

16. The wireless communication device according to claim 11, wherein: The processing circuit is further configured to, in response to determining that the target subframe is of a type that includes the unused resource elements, calculate a noise covariance of the target subframe based on signals received through the unused resource elements.

17. The wireless communication device according to claim 11, wherein: The processing circuit is further configured to: estimating a signal-to-noise ratio of the target subframe based on the noise covariance; and Do at least one of the following: performing symbol detection on the target subframe based on the signal-to-noise ratio, and Channel estimation is performed on the target subframe based on the signal-to-noise ratio.

18. A method for operating a wireless communication device operating in a narrowband Internet of Things communication independent mode, the method comprising: determining a type of a target subframe among a plurality of subframes included in a downlink signal received from an external device; determining unused resource elements in the target subframe based on the type of the target subframe; calculating a noise covariance of the target subframe based on a signal received through the unused resource elements; as well as A signal-to-noise ratio of the target subframe is estimated based on the noise covariance.

19. The operating method according to claim 18, wherein: Determining the unused resource elements includes determining the unused resource elements based on a resource grid corresponding to a type of the target subframe.

20. The operating method according to claim 18, wherein: Calculating the noise covariance further includes: The noise covariance is calculated based on signals received through the unused resource elements and signals received through narrowband reference signal resource elements in the target subframe.

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