Wireless communication device including synchronization signal detector and cell search method thereof

Abstract

A wireless communication method, comprising: receiving a wireless signal including multiple frames, wherein each frame in the multiple frames includes multiple subframes, and a current frame is initially the first frame in the frames; a) performing correlation calculations between each subframe of the current frame and a corresponding one of multiple reference signals to generate multiple current correlation values; b) accumulating the current correlation values ​​with previous correlation values ​​respectively to generate current accumulated values ​​corresponding to multiple subframes of the current frame respectively; determining whether a valid synchronization signal is detected based on the current accumulated values; and setting the next frame in the frame as a new current frame, setting the current correlation value to a new previous correlation value, and determining whether to restart to step a) based on the determination of whether the valid synchronization signal is detected.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims the benefit of priority from Korean Patent Application No. 10-2019-0009229 filed on January 24, 2019 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. Technical Field

[0003] The present invention relates to a wireless communication device and a cell searching method thereof, and more particularly, to a wireless communication device including a synchronization signal detector and a cell searching method of the wireless communication device. Background Art

[0004] In a wireless communication system including several cells, a user terminal uses a synchronization signal to search for or communicate with one of these cells. In a mobile communication system such as Long Term Evolution (LTE) or the 5th Generation (5G), a user terminal can detect a synchronization signal broadcast from a base station and thus can identify a cell formed by the base station.

[0005] The Internet of Things (IoT) is the extension of the Internet to connect to physical devices and everyday items. Various communication systems have been developed for IoT devices. For example, in the Global System for Mobile Communications (GSM) or LTE networks, the Narrowband Internet of Things (NB-IoT) supports broadband services by using narrowbands that operate in extremely weak electric fields. Therefore, the demand for fast cell searches at low signal-to-noise ratios (SNRs) is increasing. Summary of the invention

[0006] At least one embodiment of the inventive concept provides a cell search method of a wireless communication device, which detects a synchronization signal based on different accumulated quantities.

[0007] According to an exemplary embodiment of the present invention, there is provided a method for operating a wireless communication device, the method comprising: receiving a wireless signal comprising a plurality of frames, wherein each frame of the plurality of frames comprises a plurality of subframes, and a current frame is initially the first frame of the frames; a) performing correlation calculations between each subframe of the current frame and a reference signal to generate a plurality of current correlation values; b) accumulating the current correlation values ​​with the previous correlation values, respectively, to generate current accumulated values ​​corresponding to the plurality of subframes of the current frame, respectively; determining whether a valid synchronization signal is detected based on the current accumulated values; and setting a next frame of the plurality of frames as a new current frame, setting the current correlation value as a new previous correlation value, and determining whether to restart to step a) based on the determination as to whether a valid synchronization signal is detected.

[0008] According to an exemplary embodiment of the present invention, there is provided a cell search method of a wireless communication device, comprising: receiving a wireless signal in which the occurrence of each of a narrow primary synchronization signal (NPSS) and a narrow secondary synchronization signal (NSSS) is limited at a preset time interval in the wireless signal; setting a first maximum accumulation number for an operation of accumulating NPSS correlation values, wherein the wireless signal comprises a first frame and a second frame, the first frame and the second frame respectively comprising a plurality of subframes; calculating a first NPSS correlation value by performing an NPSS correlation calculation between each subframe of the first frame and a corresponding one of a plurality of NPSS reference signals; accumulating the first NPSS correlation value with a previous NPSS correlation value, respectively, to generate a first accumulation value; determining whether a valid NPSS is detected based on the first accumulation value; and when a first accumulation number obtained when the first NPSS correlation values ​​are respectively accumulated to generate the first accumulation value is less than the first maximum accumulation number, obtaining frame boundary information from the valid NPSS when the valid NPSS is detected.

[0009] According to an exemplary embodiment of the present invention, there is provided a wireless communication device, comprising: an antenna, which receives a wireless signal including a plurality of frames, in which the occurrence of each of a narrow primary synchronization signal (NPSS) and a narrow secondary synchronization signal (NSSS) is defined at a preset time interval in the wireless signal, wherein each of the plurality of frames includes a plurality of subframes; an NPSS correlator, which is configured to output an NPSS correlation value by performing an NPSS correlation calculation on a current frame based on a plurality of subframes of the current frame in the frames and an NPSS reference signal; an NPSS combiner, which is configured to accumulate the NPSS correlation values, respectively, to generate first accumulated values ​​respectively corresponding to the plurality of subframes of the current frame; and an NPSS controller, which is configured to determine whether a valid NPSS is detected based on the first accumulated value, and output a control signal for controlling the NPSS correlator based on the determination as to whether a valid NPSS is detected. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Embodiments of the present invention will be more clearly understood through the following detailed description in conjunction with the accompanying drawings, in which:

[0011] Figure 1 is a block diagram of a wireless communication system according to an exemplary embodiment of the inventive concept.

[0012] Figure 2 is a block diagram of a structure of a user equipment according to an exemplary embodiment of the present inventive concept;

[0013] Figure 3 is a diagram illustrating a wireless signal defining a narrow primary synchronization signal (NPSS) and a narrow secondary synchronization signal (NSSS) according to an exemplary embodiment of the inventive concept;

[0014] Figure 4 is a flowchart of a method of operating a user equipment according to an exemplary embodiment of the present inventive concept;

[0015] Figure 5 is a block diagram of a structure of a NPSS detector according to an exemplary embodiment of the inventive concept;

[0016] Figure 6 is a flowchart of the operation of a NPSS detector according to an exemplary embodiment of the present inventive concept;

[0017] Figure 7 is a conceptual diagram illustrating a first accumulated value and effective NPSS detection according to an exemplary embodiment of the inventive concept;

[0018] Figure 8 is a flowchart of the operation of a NPSS detector according to an exemplary embodiment of the present inventive concept;

[0019] Fig. 9 is a flowchart of the operation of a NPSS detector according to an exemplary embodiment of the present inventive concept;

[0020] Fig.10 is a conceptual diagram illustrating a first accumulated value and effective NPSS detection according to an exemplary embodiment of the inventive concept;

[0021] Fig.11 is a block diagram of a structure of an NSSS detector according to an exemplary embodiment of the inventive concept;

[0022] Fig.12 is a flowchart of the operation of a NSSS detector according to an exemplary embodiment of the inventive concept;

[0023] Fig.13 is a flowchart of the operation of a NSSS detector according to an exemplary embodiment of the inventive concept;

[0024] Fig.14 is a flowchart of an operation of a NSSS detector according to an exemplary embodiment of the inventive concept; and

[0025] Fig.15 is a block diagram of a communication device according to an exemplary embodiment of the inventive concept. DETAILED DESCRIPTION

[0026] Hereinafter, one or more exemplary embodiments of the inventive concept will be described in detail with reference to the accompanying drawings.

[0027] Figure 1 is a block diagram of a wireless communication system 1 according to an exemplary embodiment of the inventive concept. Figure 1, a wireless communication system 1 includes a user equipment 10 and a base station 20.

[0028] The base station 20 can communicate with the user equipment 10 in a wireless manner via at least one base station antenna. For example, the base station 20 and the user equipment 10 can communicate with each other via a downlink (DL) channel 2 and an uplink (UL) channel 4. For example, the user equipment 10 can download data from the base station 20 using the DL channel 2 and upload data to the base station 20 using the UL channel 4. The wireless communication network between the base station 20 and the user equipment 10 can support communication between users by allowing the sharing of available network resources. For example, via the wireless communication network, information can be sent in various ways such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), or single carrier frequency division multiple access (SC-FDMA).

[0029] Figure 1 One base station 20 is shown, but this is merely an example for ease of explanation. The wireless communication system 1 may include various numbers of base stations 20. Furthermore, the wireless communication system 1 may include different types of base stations (eg, macro base stations, micro base stations, and / or pico base stations).

[0030] The base station 20 may be a communication coverage for a certain geographic area and may provide a cell 22. In other words, the cell 22 may be a service coverage area provided by the base station 20. The user equipment 10 may search for the cell 22 provided by the base station 20 and may access the cell 22, thereby communicating with the base station 20. For example, the user equipment 10 may detect a suitable cell by searching each cell 22, may obtain the symbol and frame timing of the cell, and may synchronize with the carrier frequency.

[0031] In some embodiments, the base station 20 may be referred to as a base transceiver station (BTS), a radio base station, an access point (AP), a radio transceiver, a NodeB, an eNodeB (eNB), a Home NodeB, a Home eNodeB, or other terms. However, the terminology representing the base station 20 is not limited thereto.

[0032] The base station 20 may broadcast a synchronization signal for a cell search of the user equipment 10. For example, the base station 20 may transmit a synchronization signal including a narrow primary synchronization signal (NPSS) and a narrow secondary synchronization signal (NSSS) as a wireless signal. In detail, the base station 20 may transmit a wireless signal including a frame, and each frame may include a subframe. The base station 20 may map the NPSS to at least one subframe of each frame in units of frames. In addition, the base station 20 may map the NSSS to a subframe of each frame that is different from the subframe to which the NPSS is mapped in units of frames. The mapping process will be described in detail below.

[0033] The user equipment 10 is a wireless communication device located at a fixed location or portable, and may represent various devices capable of receiving data and / or control information from / sending data and / or control information to the base station 20 by communicating with the base station 20. For example, the user equipment 10 may be referred to as terminal equipment, a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, or a handheld device.

[0034] The user equipment 10 includes a modem 120. The modem 120 may perform various functions related to a wireless interface between the base station 20 and the user equipment 10. For example, the modem 120 may perform modulation on a signal transmitted to the base station 20 and / or demodulation on a signal received from the base station 20, as well as communication functions such as encoding and decoding required for communication with the base station 20.

[0035] In an exemplary embodiment, the modem 120 includes a synchronization signal detector 130. The synchronization signal detector 130 may be a hardware block (e.g., a device) including an analog circuit and / or a digital circuit. Alternatively, the modem 120 may also include a processor, and the synchronization signal detector 130 may be a software block including instructions executed by the processor.

[0036] The synchronization signal detector 130 receives the wireless signal output from the base station 20 and detects the synchronization signal included in the wireless signal. In an exemplary embodiment, the synchronization signal detector 130 performs correlation calculation between a preset reference signal and each subframe included in the frame in units of frames. The synchronization signal detector 130 accumulates the correlation calculation results as first accumulated values ​​corresponding to each subframe, respectively, and determines whether a valid synchronization signal is detected based on the first accumulated values.

[0037] Based on the determination as to whether a valid synchronization signal is detected, the synchronization signal detector 130 may determine whether to resume the correlation calculation. In an exemplary embodiment, the synchronization signal detector 130 sets a maximum accumulation number for accumulating the correlation calculation result as a first accumulation value, and when a valid synchronization signal is detected, even if the accumulation number to which the correlation calculation result is accumulated as the first accumulation value is less than the maximum accumulation number, the valid synchronization signal is detected as a synchronization signal for cell search.

[0038] The synchronization signal detector 130 may compare the first accumulated value with the validity determination threshold to determine whether a valid synchronization signal is detected. In an exemplary embodiment, the synchronization signal detector 130 calculates the validity determination threshold based on the accumulated number of correlation calculation results accumulated as the first accumulated value, and determines whether a valid synchronization signal is detected based on a comparison result obtained using the validity determination threshold and the first accumulated value. For example, the synchronization signal detector 130 may derive a first value based on a peak value and a statistical value of the first accumulated value, and compare the first value with the validity determination threshold to determine whether a valid synchronization signal is detected.

[0039] In an exemplary embodiment, the synchronization signal detector 130 detects NPSS as a synchronization signal according to the above operation. For example, the user equipment 10 can find frame boundary information by using the detected NPSS. In addition, by using the detected NPSS, the user equipment 10 can also find frequency offset information to be reflected when detecting NSSS. In an exemplary embodiment, the synchronization signal detector 130 detects NSSS as a synchronization signal according to the above operation.

[0040] Figure 2 is a user equipment (eg, Figure 1 Block diagram of the structure of user equipment 10).

[0041] refer to Figure 2 , user equipment 10 includes an antenna 100, a radio frequency (RF) circuit 110, a modem 120, a processor 160, a memory 170, and a system interconnect 180 (e.g., a data bus). Each component included in user equipment 10 may be a hardware block including an analog circuit and / or a digital circuit or a software block including instructions executed by a processor.

[0042] The RF circuit 110 may receive a wireless signal transmitted from the base station 20 through the antenna 100. For example, the RF circuit 110 may convert a wireless signal in a frequency band of a high main frequency to a baseband, and may output the wireless signal to the modem 120. In other words, the RF circuit 110 may demodulate the received wireless signal so that the modem 120, the processor 160, or the memory 170 may process the signal. In addition, the RF circuit 110 may receive data from the modem 120 and may modulate the data, thereby transmitting the modulated data to the base station 20 through the antenna 100.

[0043] Processor 160 may include an intelligent hardware device, such as a central processing unit (CPU), a microcontroller, an application processor (AP), or a graphics processing unit (GPU). Memory 170 may include a volatile memory, such as a dynamic random access memory (DRAM) or a synchronous dynamic random access memory (SDRAM). In addition, memory 170 may include a non-volatile memory, such as an electrically erasable programmable read-only memory (EEPROM), a flash memory, a phase change random access memory (PRAM), a resistive random access memory (RRAM), a nano floating gate memory (NFGM), a polymer random access memory (PoRAM), a magnetic random access memory (MRAM), or a ferroelectric random access memory (FRAM).

[0044] The memory 170 may store software codes that are computer-readable and / or computer-executable and include instructions. For example, the memory 170 may store a signal processing algorithm for wireless signal processing.

[0045] System interconnect 180 may include a bus that applies a protocol having certain bus standards. For example, the Advanced Microcontroller Bus Architecture (AMBA) protocol developed by AdvancedRISC Machine (ARM) may be used as a bus standard. Advanced High Performance Bus (AHB), Advanced Peripheral Bus (APB), Advanced Extensible Interface (AXI), AXI4, or AXI Coherence Extension (ACE) may be included in each bus type of the AMBA protocol.

[0046] In an exemplary embodiment, the synchronization signal detector 130 detects NPSS and NSSS based on a wireless signal in which the occurrence of each of the NPSS and the NSSS received through the antenna 100 is defined at a preset time interval. The synchronization signal detector 130 includes an NPSS detector 140 and an NSSS detector 150. In an exemplary embodiment, the NPSS detector 140 performs NPSS correlation calculation between each subframe and the NPSS reference signal in units of frames, thereby calculating an NPSS correlation value. The NPSS detector 140 may accumulate the calculated NPSS correlation values ​​as first accumulated values ​​corresponding to the subframes, respectively.

[0047] The number of times the NPSS correlation value is accumulated as the first accumulated value may increase in units of frames. In an exemplary embodiment, the NPSS detector 140 sets a maximum accumulation number for the above-mentioned accumulation operation and performs the accumulation operation of accumulating the NPSS correlation value within a range less than or equal to the maximum accumulation number.

[0048] The NPSS detector 140 may determine whether a valid NPSS is detected based on the first accumulated value. In an exemplary embodiment, even if the number of accumulations obtained when the NPSS-related values ​​calculated for the subframes of any frame are respectively accumulated as the first accumulated value is less than the maximum accumulated number, since a valid NPSS is detected based on the first accumulated value, the NPSS detection operation may be terminated. In other words, although the number of times the accumulation operation is performed is less than the maximum accumulated number, since a valid NPSS is detected based on the first accumulated value, the NPSS detector 140 may detect the valid NPSS as the NPSS for cell search. The NPSS detector 140 may obtain frame boundary information by using the detected NPSS. In addition, the NPSS detector 140 may also obtain frequency offset information to be reflected when detecting NSSS by using the detected NPSS.

[0049] The NSSS detector 150 may detect the NSSS based on the frame boundary information obtained by using the NPSS detector 140. For example, the NSSS detector 150 may predict the NSSS position based on the frame boundary information obtained by using the NPSS detector 140, and may perform NSSS correlation calculation between each subframe and the NSSS reference signal based on the predicted NSSS position, thereby calculating the NSSS correlation value. The NSSS detector 150 may respectively accumulate the calculated NSSS correlation values ​​as second accumulated values ​​respectively corresponding to the subframes.

[0050] The number of times the NSSS correlation value is accumulated as the second accumulated value may increase in units of frames. In an exemplary embodiment, the NSSS detector 150 sets a maximum accumulation number regarding the accumulation operation and performs the accumulation operation of accumulating the NSSS correlation value within a range less than or equal to the maximum accumulation number.

[0051] In an exemplary embodiment, the NSSS detector 150 determines whether a valid NSSS is detected based on the second accumulated value. In an exemplary embodiment, although the number of accumulations obtained when the NSSS-related values ​​calculated for the subframes of an arbitrary frame are respectively accumulated as the second accumulated value is less than the maximum accumulated number, since a valid NSSS is detected based on the second accumulated value, the NSSS detection operation can be terminated. In other words, although the number of times the accumulation operation is performed is less than the maximum accumulated number, since a valid NSSS is detected based on the second accumulated value, the NSSS detector 150 can detect the valid NSSS as the NSSS for cell search. The NSSS detector 150 can obtain cell ID information by using the detected NSSS.

[0052] Figure 3 is a diagram illustrating a wireless signal defining NPSS and NSSS according to an exemplary embodiment of the inventive concept.

[0053] refer to Figure 3 , the wireless signal WS output from the base station 20 includes frames FR_1 to FR_3, and each of the frames FR_1 to FR_3 includes subframes (e.g., subframes 0 to 9). In the wireless signal WS, the occurrence of each of the NPSS and the NSSS may be defined at a preset time interval. For example, the base station 20 may transmit the NPSS and the NSSS in a narrow band of the downlink system bandwidth.

[0054] In an exemplary embodiment, the NPSS is defined in subframe 5 of each of frames FR_1 to FR_3. In detail, each subframe may include symbols (e.g., symbols 0 to 13), and the NPSS may be defined in symbols 3 to 13 of subframe 5 of each of frames FR_1 to FR_3. For example, the NPSS may be transmitted by using adjacent OFDM symbols (e.g., adjacent OFDM symbols in subframe 5). In an exemplary embodiment, the NPSS is a sequence encoded in the base station 20 according to the Zadoff-Chu method.

[0055] In an exemplary embodiment, the NSSS is alternately defined in subframe 9 of each frame (e.g., frames FR_1 to FR_3). For example, the NSSS may be present in the first frame FR_1, not in the second frame FR_2, and in the third frame FR_3. In detail, the NSSS may be defined in symbols 3 to 13 of subframe 9 of each frame. For example, the NSSS may be transmitted by using adjacent OFDM symbols (e.g., adjacent OFDM symbols in subframe 9). In an exemplary embodiment, the NSSS may be a sequence encoded in the base station 20 according to at least one of the Zadoff-Chu method, the Hadamard method, and the phase rotation method.

[0056] Figure 4 is a flow chart of a method for operating a user equipment according to an exemplary embodiment of the present invention. Figure 4 Shows Figure 2 The present invention is a part of a cell search method of the user equipment 10.

[0057] refer to Figure 4In operation S10, the user equipment 10 receives a wireless signal WS including a frame through the antenna 100. For example, each frame included in the wireless signal WS may include a subframe, and a first synchronization signal may be defined in at least one of the subframes for cell search. For example, at least one of the NPSS and the NSSS may be defined as a first synchronization signal in at least one of the subframes. For example, the modem 120 may periodically sample the received wireless signal to retrieve data representing a frame of the wireless signal WS, divide the retrieved data into sections corresponding to each subframe, and store the sections in an internal buffer or memory 170 so that relevant calculations may be performed later on each section.

[0058] Next, in operation S20, the user equipment 10 performs a first correlation calculation between each subframe and the first reference signal in units of frames. The first reference signal may be preset in the synchronization signal detector 130 for the first correlation calculation. For example, the first correlation calculation may be performed on each of the above segments in the first frame with respect to a corresponding one of the first reference signals to generate a first correlation value associated with the first frame.

[0059] In operation S30, the user equipment 10 accumulates the first correlation calculation result as each first accumulated value. Each first accumulated value may correspond to each subframe of the frame, and may be a value for accumulating the correlation value obtained according to the first correlation calculation. For example, when the wireless signal WS is a wireless signal with a relatively weak electric field, the synchronization signal detector 130 may accumulate the correlation value, and thus distinguish the first synchronization signal from the noise. The first accumulated value may be generated by adding the first correlation value to the previous correlation value, respectively. However, when operation S20 is performed only once, the first accumulated value is the same as the first correlation value, and the previous correlation value may be set as the first correlation value.

[0060] In operation S40, the user equipment 10 determines whether a valid first synchronization signal is detected based on the first accumulated value. Based on the determination as to whether a valid first synchronization signal is detected, the user equipment 10 determines whether to restart the first correlation calculation performed in operation S20. For example, when a valid first synchronization signal is not detected, the user equipment 10 restarts operation S20.

[0061] For example, after operation S20 is performed on the first frame and no valid first synchronization signal is detected, operation S20 may be performed on the second frame to generate a second correlation value. For example, the second frame will be divided into segments corresponding to its respective subframes to correlate these segments with the reference signal to generate a second correlation value. Then, operation S30 will result in the previous correlation value (i.e., the first correlation value) being added to the second correlation value to generate an updated cumulative value. For example, the correlation value associated with the first subframe of the first frame will be added to the correlation value associated with the first subframe of the second frame, the correlation value associated with the second subframe of the first frame will be added to the correlation value associated with the second subframe of the second frame, and the like. Then, operation S40 will be performed on the updated cumulative value to determine whether a valid first synchronization signal is detected.

[0062] In an exemplary embodiment, the user equipment 10 sets a maximum accumulation number and performs the accumulation operation in operation S30 within the maximum accumulation number. In other words, when a valid first synchronization signal is not detected in operation S40, the user equipment 10 may repeatedly perform operations S20 and S30 within the maximum accumulation number.

[0063] In an exemplary embodiment, when the number of times the accumulation operation in operation S30 is performed is less than the maximum accumulation number, and when a valid first synchronization signal is detected in operation S40, the user equipment 10 detects the valid first synchronization signal as the first synchronization signal for cell search, and can perform cell search based on the detected first synchronization signal. In other words, because a valid first synchronization signal is detected, the user equipment 10 can detect the first synchronization signal for cell search without additionally performing operations S20 and S30 even if the number of times the accumulation operation in operation S30 is performed is less than the maximum accumulation number. For example, if the maximum accumulation number is 3 and the system is able to detect a valid first synchronization signal from the first two frames, it is not necessary to perform operations S20 and S30 on the third frame.

[0064] As described above, according to at least one embodiment of the inventive concept, during cell search, the user equipment 10 can adaptively change the number of times the accumulation operation is performed, and then can operate. Therefore, the user equipment 10 can reduce the time period spent searching for cells and the amount of power consumed. For example, instead of always performing a fixed number of correlation calculations and accumulations, these steps can be performed only until a sufficiently effective synchronization signal has been identified.

[0065] Figure 5 is a block diagram of the structure of an NPSS detector according to an exemplary embodiment of the inventive concept. For example, Figure 5 Shows Figure 2 Detailed structure of the NPSS detector 140 .

[0066] refer to Figure 5 , the NPSS detector 140 includes a synchronous filter 141, an input buffer 142, a downsampler 143, an NPSS correlator 144 (e.g., an analog circuit, a digital circuit, or software), an NPSS combiner 145 (e.g., an analog circuit, a digital circuit, or software), and an NPSS controller 146 (e.g., a control circuit). The synchronous filter 141 can remove or control signals other than the desired received signal (e.g., the synchronization signal) in the frequency band from the wireless signal WS. For example, the synchronous filter 141 can include a low-pass filter. For example, the synchronous filter 141 can filter out undesired frequency components from the wireless signal WS.

[0067] The input buffer 142 may buffer the signal filtered by the synchronous filter 141. In an exemplary embodiment, the input buffer 142 samples the signal filtered by the synchronous filter 141 at a specific sampling rate and stores the sampled signal.

[0068] The downsampler 143 may downsample the signal stored in the input buffer 142 at a specific sampling rate. For example, the downsampler 143 may perform 1 / 8 downsampling on the signal stored in the input buffer 142 to generate a downsampled signal, and may output the downsampled signal to the NPSS correlator 144. However, this is merely an example, as the downsampling rate may vary. For example, the downsampler 143 may perform 1 / 4 downsampling, 1 / 10 downsampling, etc. For example, the number of downsampled signals may correspond to the number of subframes.

[0069] The NPSS correlator 144 may perform NPSS correlation calculations on the down-sampled signals and the pre-set NPSS reference signal P_ref. For example, the NPSS correlator 144 may perform NPSS correlation calculations between each subframe and the NPSS reference signal P_ref in units of frames, and may output NPSS correlation values ​​P_cor. In an exemplary embodiment, the NPSS correlator 144 performs NPSS correlation calculations between each subframe and the NPSS reference signal P_ref according to at least one of full correlation, symbol-based correlation, and differential correlation. For example, the NPSS correlator 144 may perform NPSS correlation calculations on one of the down-sampled signals and a corresponding one of the NPSS reference signal P_ref to generate an NPSS correlation value, and repeat the process for each down-sampled signal to generate an NPSS correlation value P_cor.

[0070] The NPSS combiner 145 may accumulate the NPSS correlation value P_cor as a first accumulated value P_ac, and may output the first accumulated value P_ac to the NPSS controller 146. In an exemplary embodiment, a determination as to whether to perform an accumulation operation in the NPSS combiner 145 may be made according to a maximum accumulation number P_max under the control of the NPSS controller 146. In other words, the NPSS combiner 145 may accumulate the NPSS correlation value P_cor as the first accumulated value P_ac a number of times less than the maximum accumulation number P_max.

[0071] For example, each first accumulated value P_ac corresponds to each subframe, and can be used to repeatedly accumulate each NPSS related value. In an exemplary embodiment, when a valid NPSS is not detected based on the first accumulated value P_ac, and when the number of accumulations is less than the maximum accumulation number P_max, the operation of the NPSS correlator 144 and the operation of the NPSS combiner 145 can be restarted under the control of the NPSS controller 146.

[0072] For example, the NPSS correlator 144 performs correlation calculation according to the full correlation, and then the NPSS combiner 145 performs accumulation operation, and the operation of the NPSS correlator 144 and the operation of the NPSS combiner 145 can be expressed by the following [Equation 1].

[0073] [Equation 1]

[0074]

[0075] In [Equation 1], r c (t) can represent the cth accumulated wireless signal, N sym (m-1) can represent the (m-1)th symbol value, and z m M may represent the NPSS reference signal corresponding to the mth symbol. In addition, C may represent the maximum accumulation quantity.

[0076] As another example, the NPSS correlator 144 performs correlation calculation according to symbol-based correlation, and then the NPSS combiner 145 performs accumulation operation, and the operation of the NPSS correlator 144 and the operation of the NPSS combiner 145 can be expressed by the following [Equation 2].

[0077] [Equation 2]

[0078]

[0079] As another example, the NPSS correlator 144 performs correlation calculation according to differential correlation and then the NPSS combiner 145 performs accumulation operation, and the operation of the NPSS correlator 144 and the operation of the NPSS combiner 145 can be represented by the following [Equation 3].

[0080] [Equation 3]

[0081]

[0082]

[0083] The NPSS controller 146 may determine whether a valid NPSS is detected based on the first accumulated value P_ac. In an example embodiment, the NPSS controller 146 may output a control signal P_con for controlling the NPSS correlator 144 based on the maximum accumulated number P_max and the determination as to whether a valid NPSS is detected.

[0084] For example, when a valid NPSS is detected based on the first accumulated value P_ac, even if the accumulated number is less than the maximum accumulated number P_max, the NPSS controller 146 may detect the NPSS as the NPSS for cell search and may output NPSS related information P_inf. For example, the NPSS related information P_inf may include frame boundary information and frequency offset information.

[0085] For example, when a valid NPSS is not detected based on the first accumulated value P_ac, and when the accumulated number is less than the maximum accumulated number P_max, the NPSS controller 146 may output a control signal P_con to operate the NPSS correlator 144. Therefore, when a valid NPSS is not detected from a specific frame, the NPSS controller 146 may restart the operation of the NPSS correlator 144 and the operation of the NPSS combiner 145 for the next frame.

[0086] Figure 6 is a flow chart of the operation of the NPSS detector according to an exemplary embodiment of the inventive concept. For example, Figure 6 Shows Figure 5 Partial operation of the NPSS detector 140 .

[0087] refer to Figure 6 In operation S100, the NPSS detector 140 sets a maximum accumulation number P_max and initializes an accumulation count. For example, the accumulation count may be a variable for counting the number of times the NPSS combiner 145 performs an accumulation operation.

[0088] In operation S110, the NPSS detector 140 performs NPSS correlation calculation between each subframe and the NPSS reference signal P_ref in units of frames, and accumulates the NPSS correlation calculation result as a first accumulated value P_ac, thereby increasing the accumulated count. The NPSS correlation calculation may be performed by the NPSS correlator 144 based on the NPSS reference signal P_ref, and the accumulation operation may be performed by the NPSS combiner 145 based on the NPSS correlation value P_cor. For example, the NPSS correlation calculation may be performed by the NPSS correlator 144 on the subframes of the first frame and the NPSS reference signal P_ref to generate the NPSS correlation value P_cor, and since this is the first time, the NPSS combiner 145 sets the first accumulated value P_ac to the NPSS correlation value P_cor, and increases the accumulated count to 1.

[0089] In operation S120, the NPSS detector 140 determines whether a valid NPSS is detected based on the first accumulated value P_ac. In addition, based on the determination as to whether a valid NPSS is detected, the NPSS detector 140 may determine whether to restart the NPSS-related calculation and accumulation operations.

[0090] For example, in operation S130, when a valid NPSS is not detected, the NPSS detector 140 determines whether the current accumulated count is equal to or greater than the maximum accumulated number P_max. When the current accumulated count is equal to or greater than the maximum accumulated number P_max, the NPSS detector 140 terminates the NPSS detection operation. Otherwise, when the current accumulated count is less than the maximum accumulated number P_max, the NPSS detector 140 restarts to operation S110. For example, if a valid NPSS has not been detected from the accumulated value generated from the first frame and the current accumulated count is less than the maximum accumulated number, the NPSS correlator 144 may perform NPSS correlation calculation on the subframe of the second frame and the NPSS reference signal P_ref to generate a new NPSS correlation value. Since this is the second time, the NPSS combiner 145 will add the previous accumulated value to the new NPSS correlation value to generate a new accumulated value, and the accumulated count will increase to 2.

[0091] For example, in operation S140, when a valid NPSS is detected, the NPSS detector 140 detects the valid NPSS as the NPSS for cell search and obtains NPSS-related information P_inf. The NPSS-related information P_inf may include information on which the NSSS detection operation of the synchronization signal detector 130 is based.

[0092] Figure 7 is a conceptual diagram illustrating a first accumulated value and effective NPSS detection according to an exemplary embodiment of the inventive concept.

[0093] refer to Figure 7 , the NPSS related value is accumulated N times in units of frame FR (where N is a positive integer equal to or greater than 2). For example, NPSS may be defined in subframe 5, and the NPSS detector 140 may determine whether a valid NPSS is detected by comparing the first accumulated value with the validity determination threshold NPSS_TH.

[0094] In an exemplary embodiment, the NPSS detector 140 derives the first value based on a peak value of the first accumulated value in each accumulated count and a statistical value about the first accumulated value. In an exemplary embodiment, the NPSS detector 140 compares the first value with a validity determination threshold NPSS_TH and determines whether a valid NPSS is detected based on the comparison.

[0095] For example, the statistical value of the first accumulated value may be the minimum value in the first accumulated value, and the first value may be the ratio of the peak value to the minimum value. As another example, the statistical value of the first accumulated value may be the average value of the first accumulated value, and the first value may be the ratio of the peak value to the average value.

[0096] In an exemplary embodiment, the NPSS detector 140 determines whether a valid NPSS is detected in response to a state that the position of the peak of the first accumulated value is maintained the same or similarly during a specific accumulated count period. In other words, when the position of the peak of the first accumulated value is maintained the same or similarly during a preset threshold accumulated number, the NPSS detector 140 can determine the position of the peak as the position where the NPSS is defined. For example, if the preset threshold accumulated number is 2, and the position of the peak is the fourth subframe during the first accumulated period, the fifth subframe during the second accumulated period, and then the fifth subframe again during the third accumulated period, it can be concluded that the NPSS is defined in the fifth subframe.

[0097] Figure 8 is a flowchart of an operation of a NPSS detector according to an exemplary embodiment of the inventive concept.

[0098] refer to Figure 8, in operation S200, the NPSS detector 140 sets a maximum accumulation number P_max and initializes an accumulation count. Next, in operation S210, the NPSS detector 140 initializes a determination count. For example, the determination count may be a variable set to perform a valid NPSS detection operation after performing the NPSS-related calculation and accumulation operation at least twice. In other words, the NPSS detector 140 may perform the NPSS-related calculation and accumulation operation M times (where M is a positive integer equal to or greater than 2) continuously, and may determine whether a valid NPSS is detected based on the output first accumulation value. M may vary. For example, based on the determination as to whether a valid NPSS is detected, the value of M may be adaptively changed.

[0099] To make the determination, in operation S220, the NPSS detector 140 may perform NPSS correlation calculation between each subframe and the NPSS reference signal P_ref in units of frames, and accumulate the NPSS correlation calculation result as a first accumulated value P_ac, thereby increasing the accumulated count and the determination count, respectively. Then, in operation S230, the NPSS detector 140 may determine whether the determination count is greater than M.

[0100] When it is determined that the count is less than or equal to M, the NPSS detector 140 performs operation S220 again. In operation S240 , when it is determined that the count is greater than M, the NPSS detector 140 determines whether a valid NPSS is detected.

[0101] For example, in operation S260, when a valid NPSS is detected, the NPSS detector 140 may detect the valid NPSS as the NPSS for cell search, and may obtain NPSS-related information P_inf. Otherwise, in operation S250, when a valid NPSS is not detected, the NPSS detector 140 determines whether the current cumulative count is equal to or greater than the maximum cumulative number P_max. When the current cumulative count is equal to or greater than the maximum cumulative number P_max, the NPSS detector 140 terminates the NPSS detection operation, and when the current cumulative count is less than the maximum cumulative number P_max, the NPSS detector 140 restarts operation S210.

[0102] Fig. 9 is a flowchart of an operation of a NPSS detector according to an exemplary embodiment of the inventive concept.

[0103] refer to Fig. 9, in operation S300, the NPSS detector 140 sets a maximum accumulation number P_max and initializes an accumulation count. Then, in operation S310, the NPSS detector 140 performs NPSS correlation calculation between each subframe and the NPSS reference signal P_ref in units of frames, and accumulates the NPSS correlation calculation result as a first accumulation value P_ac, thereby increasing the accumulation count. In operation S320, the NPSS detector 140 determines whether a valid NPSS is detected based on the first accumulation value P_ac. When a valid NPSS is detected, the NPSS detector 140 may detect the valid NPSS as the NPSS for cell search, and may obtain NPSS-related information P_inf.

[0104] In operation S330, when a valid NPSS is not detected, the NPSS detector 140 determines whether the current accumulation count is equal to or greater than the maximum accumulation number P_max. When the current accumulation count is equal to or greater than the maximum accumulation number P_max, the NPSS detector 140 terminates the NPSS detection operation.

[0105] In operation S340, when the current accumulated count is less than the maximum accumulated number P_max, the NPSS detector 140 adjusts the validity determination threshold on which the valid NPSS detection is based. In an exemplary embodiment, the NPSS detector 140 adjusts the validity determination threshold based on the accumulated count. For example, as the accumulated count increases, the NPSS detector 140 may set the size of the validity determination threshold to be smaller. For example, if a valid NPSS has not been detected and the accumulated count has become equal to the maximum accumulated number, the validity determination threshold may be reduced to increase the chance of finding a valid NPSS. For example, the adjustment of the validity determination threshold may be performed by the NPSS controller 146 based on the accumulated count.

[0106] In an exemplary embodiment, the NPSS detector 140 adjusts the validity determination threshold based on a false alarm rate when a valid first synchronization signal is detected. In an exemplary embodiment, the NPSS detector 140 adjusts the validity determination threshold based on channel information for receiving wireless signals.

[0107] Fig.10 is a conceptual diagram illustrating a first accumulated value and effective NPSS detection according to an exemplary embodiment of the inventive concept.

[0108] refer to Fig.10 As the accumulated count increases, the validity determination threshold may change. For example, the NPSS detector 140 may set a first validity determination threshold NPSS_TH1 when the accumulated count is 1, a second validity determination threshold NPSS_TH2 when the accumulated count is 2, and an Nth validity determination threshold NPSS_THN when the accumulated count is N.

[0109] In an exemplary embodiment, the second validity determination threshold NPSS_TH2 is less than or equal to the first validity determination threshold NPSS_TH1, and the Nth validity determination threshold NPSS_THN is less than or equal to the second validity determination threshold NPSS_TH2. In other words, as the accumulated count increases, the NPSS detector 140 may adaptively reduce the validity determination threshold.

[0110] In the present embodiment, it is described that the validity determination threshold value changes in each accumulated count. However, this is merely an example, as the embodiments of the inventive concept are not limited thereto. For example, after the accumulated count increases by a certain number equal to or greater than 2, the NPSS detector 140 may adaptively reduce the validity determination threshold value.

[0111] Fig.11 is a block diagram of the structure of an NSSS detector according to an exemplary embodiment of the inventive concept. For example, Fig.11 Shows Figure 2 Detailed structure of the NSSS detector 150.

[0112] refer to Fig.11 , the NSSS detector 150 includes a synchronous filter 158, an input buffer 151, a downsampler 152, a compensator 153, a fast Fourier transform (FFT) converter 154, a NSSS correlator 155, a NSSS combiner 156, and a NSSS controller 157. The synchronous filter 158 can remove or control signals in the frequency band other than the signal desired to be received from the input wireless signal WS. For example, the synchronous filter 158 can include a low-pass filter. For example, the synchronous filter 158 can filter out certain frequency components from the input wireless signal WS. The input buffer 151 can predict the NSSS position based on the NPSS-related information P_inf (e.g., frame boundary information) output from the NPSS detector 140 for the signal filtered by the synchronous filter 158. In an exemplary embodiment, the input buffer 151 samples the signal filtered by the synchronous filter 158 at a specific sampling rate and stores the sampled signal.

[0113] The downsampler 152 may downsample the signal stored in the input buffer 151 at a specific sampling rate. For example, the downsampler 152 may perform 1 / 8 downsampling on the signal stored in the input buffer 151, and may output the downsampled signal to the compensator 153. However, this is merely an example, as the downsampling rate may vary.

[0114] The compensator 153 may compensate the down-sampled signal based on the NPSS-related information P_inf output from the NPSS detector 140. For example, the NPSS-related information P_inf may include frequency offset information, and the compensator 153 may perform a compensation operation on the down-sampled signal based on the frequency offset information. The FFT converter 154 may convert the signal in the time domain output from the compensator 153 into a signal in the frequency domain based on FFT calculation.

[0115] The NSSS correlator 155 may perform NSSS correlation calculations on the FFT-converted signal and the preset NSSS reference signal S_ref. For example, the NSSS correlator 155 may perform NSSS correlation calculations between each of the candidate subframes predicted as the NSSS position based on NSSS detection and the NSSS reference signal S_ref in units of frames, thereby outputting an NSSS correlation value S_cor. For example, the NSSS correlator 155 may perform NSSS correlation calculations between each subframe and the NSSS reference signal S_ref based on full correlation.

[0116] The NSSS combiner 156 may accumulate the NSSS correlation value S_cor as a second accumulated value S_ac, and may output the second accumulated value S_ac to the NSSS controller 157. In an exemplary embodiment, a determination as to whether an accumulation operation is performed by the NSSS combiner 156 is made according to the maximum accumulation number S_max under the control of the NSSS controller 157. In other words, the NSSS combiner 156 may accumulate the NSSS correlation value S_cor as the second accumulated value S_ac a number of times less than the maximum accumulation number S_max.

[0117] For example, each second accumulated value S_ac may correspond to each subframe, and may be used to repeatedly accumulate each NSSS correlation value S_cor.

[0118] In an exemplary embodiment, when a valid NSSS is not detected based on the second accumulated value S_ac and when the accumulated number is less than the maximum accumulated number S_max, the operation of the NSSS correlator 155 and the operation of the NSSS combiner 156 are restarted under the control of the NSSS controller 157 .

[0119] For example, after the NSSS correlator 155 performs correlation calculation according to full correlation and the NSSS combiner 156 performs accumulation operation, the operation of the NSSS correlator 155 and the operation of the NSSS combiner 156 can be represented by the following [Equation 4].

[0120] [Equation 4]

[0121]

[0122] In [Equation 4], The FFT of a wireless signal may represent, for example, 11 segments of symbol data, each segment of symbol data including 12 subcarriers. For example, n may represent a signal indicating 504 cell IDs, and (u, q) may represent 132 Zadoff indices and 4 Hadamard matrix indices, respectively. f When the frame index is 10ms, include And a signal indicating four frame boundary indexes of 20ms can be represented.

[0123] The NSSS controller 157 may determine whether a valid NSSS is detected based on the second accumulated value S_ac. In an exemplary embodiment, the NSSS controller 157 outputs a control signal S_con for controlling the NSSS correlator 155 based on the maximum accumulated number S_max and the determination as to whether a valid NSSS is detected.

[0124] For example, when a valid NSSS is detected based on the second accumulated value S_ac, even if the accumulated number is less than the maximum accumulated number S_max, the NSSS controller 157 may detect the valid NSSS as the NSSS for cell search and may output NSSS related information S_inf. For example, the NSSS related information S_inf may include cell ID information and / or frequency boundary information (e.g., 80ms boundary information).

[0125] For example, when a valid NSSS is not detected based on the second accumulated value S_ac, and when the accumulated number is less than the maximum accumulated number S_max, the NSSS controller 157 may output a control signal S_con to drive the NSSS correlator 155. When a valid NSSS is not detected from a specific frame, the NSSS controller 157 may restart the operation of the NSSS correlator 155 and the operation of the NSSS combiner 156 for the next frame.

[0126] Fig.12 is a flow chart of the operation of the NSSS detector according to an exemplary embodiment of the inventive concept. Fig.12 Shows Fig.11 Part of the operation of the NSSS detector 150.

[0127] refer to Fig.12 In operation 400, the NSSS detector 150 sets the maximum accumulation number S_max and initializes the accumulation count. For example, the accumulation count may be a variable for counting the number of times the NSSS combiner 156 performs an accumulation operation.

[0128] In operation S410, the NSSS detector 150 performs NSSS correlation calculations between each subframe and the NSSS reference signal S_ref in units of frames, and accumulates the NSSS correlation calculation results as a second accumulated value S_ac, thereby increasing the accumulated count. The NSSS correlation calculation may be performed by the NSSS correlator 155 based on the NSSS reference signal S_ref, and the accumulation operation may be performed by the NSSS combiner 156 based on the NSSS correlation value S_cor. For example, when the NSSS detector 150 performs NSSS correlation calculations between each subframe of the first frame and the NSSS reference signal S_ref to generate a second correlation value, since this is the first time, the second accumulated value S_ac is set to the second correlation value. For example, when the NSSS detector 150 next performs NSSS correlation calculations between each subframe of the second frame and the NSSS reference signal S_ref to generate a new second correlation value, since this is the second time, the new second correlation values ​​are added to the previous second accumulated values ​​to generate a new second accumulated value.

[0129] In operation S420, the NSSS detector 150 determines whether a valid NSSS is detected based on the second accumulated value S_ac. In addition, the NSSS detector 150 may determine whether to restart the NSSS-related calculation and accumulation operation based on the determination as to whether a valid NSSS is detected.

[0130] In an exemplary embodiment, the NSSS detector 150 derives the second value based on the peak value of the second accumulated value in each accumulated count and the statistical value about the second accumulated value. The NSSS detector 150 may compare the second value with the validity determination threshold to determine whether a valid NSSS is detected. In detail, the operation of the NSSS detector 150 may be similar to that of the reference numeral 140. Figure 7 The operation of the NPSS detector 140 is described.

[0131] For example, in operation S430, when a valid NSSS is not detected, the NSSS detector 150 determines whether the current accumulated count is equal to or greater than the maximum accumulated number S_max. When the current accumulated count is equal to or greater than the maximum accumulated number S_max, the NSSS detector 150 terminates the NSSS detection operation. Otherwise, when the current accumulated count is less than the maximum accumulated number S_max, the NSSS detector 150 restarts to operation S410.

[0132] In operation S440, for example, when a valid NSSS is detected, the NSSS detector 150 detects the valid NSSS as the NSSS for cell search and may obtain NSSS-related information S_inf. For example, the NSSS-related information S_inf may include cell ID information.

[0133] Fig.13 is a flowchart of an operation of a NSSS detector according to an exemplary embodiment of the inventive concept.

[0134] refer to Fig.13 , in operation S400a, the NSSS detector 150 sets the maximum accumulation number S_max and initializes the accumulation count. Then, in operation S410a, the NSSS detector 150 performs NSSS correlation calculation between each subframe and the NSSS reference signal S_ref, and accumulates the NSSS correlation calculation result as a second accumulation value S_ac, thereby increasing the accumulation count. Next, in operation S420a, the NSSS detector 150 determines whether a valid NSSS is detected based on the second accumulation value S_ac. When a valid NSSS is detected, the NSSS detector 150 can detect the valid NSSS as the NSSS for cell search, and can obtain NSSS-related information S_inf.

[0135] In operation S430a, when a valid NSSS is not detected, the NSSS detector 150 determines whether the current accumulation count is equal to or greater than the maximum accumulation number S_max. When the current accumulation count is equal to or greater than the maximum accumulation number S_max, the NSSS detector 150 terminates the NSSS detection operation.

[0136] In operation S440a, when the current accumulated count is less than the maximum accumulated count S_max, the NSSS detector 150 adjusts the validity determination threshold on which the detection of the valid NSSS is based. In an exemplary embodiment, the NSSS detector 150 adjusts the validity determination threshold based on the accumulated count. For example, as the accumulated count increases, the NSSS detector 150 may set the size of the validity determination threshold to be smaller. For example, the adjustment of the validity determination threshold may be performed by the NSSS controller 157 based on the accumulated count.

[0137] In operation S450a, when a valid NSSS is detected or the current accumulation count is equal to or greater than the maximum accumulation number S_max, the NSSS detector 150 obtains NSSS-related information.

[0138] Fig.14 is a flowchart of an operation of the NSSS detector 150 according to an exemplary embodiment of the inventive concept.

[0139] refer to Fig.14In operation S500, the NSSS detector 150 sets a maximum accumulation number S_max and initializes an accumulation count. Then, in operation S510, the NSSS detector 150 performs NSSS correlation calculation between each subframe and the NSSS reference signal S_ref, and accumulates the NSSS correlation calculation result as a second accumulation value S_ac, thereby increasing the accumulation count.

[0140] In operation S520, the NSSS detector 150 determines whether the current cumulative count is equal to or greater than the maximum cumulative number S_max. When the current cumulative count is less than the maximum cumulative number S_max, the NSSS detector 150 restarts operation S510. Otherwise, in operation S530, when the current cumulative count is equal to or greater than the maximum cumulative number S_max, the NSSS detector 150 detects NSSS based on a second cumulative value corresponding to the cumulative count, and NSSS-related information can be obtained. Therefore, when NPSS is detected by adaptively changing the cumulative number and then NSSS is detected based on the detected NPSS, NSSS can be detected when the cumulative count becomes equal to the maximum cumulative number.

[0141] Fig.15 is a block diagram of a communication device according to an exemplary embodiment of the inventive concept.

[0142] refer to Fig.15 , the wireless communication device 1000 as an example of a communication device may include an application specific integrated circuit (ASIC) 1010, an application specific instruction set processor (ASIP) 1030, a memory 1050, a main processor 1070, and a main memory 1090. At least two of the ASIC 1010, the ASIP 1030, and the main processor 1070 may communicate with each other. In addition, at least two of the ASIC 1010, the ASIP 1030, the memory 1050, the main processor 1070, and the main memory 1090 may be embedded in one chip.

[0143] ASIP 1030 may be an integrated circuit customized for a specific purpose, supporting an instruction set dedicated to a specific application, and executing instructions in the instruction set. Memory 1050 may communicate with ASIP 1030 and may store instructions executed by ASIP 1030 as a non-transitory storage medium. Memory 1050 may include any type of memory accessible to ASIP 1030, such as random access memory (RAM), read-only memory (ROM), tape, disk, optical disk, volatile memory, non-volatile memory, or a combination thereof. ASIP 1030 or main processor 1070 may execute a series of instructions stored in main memory 1090 to detect NPSS and NSSS from wireless signals, and search for cells based on the detected NPSS and NSSS, as described in reference. Figures 1 to 14 described.

[0144] The main processor 1070 may execute instructions to control the wireless communication device 1000. For example, the main processor 1070 may control the ASIC 1010 or the ASIP 1030, and may process data received via a wireless communication network or a user's input to the wireless communication device 1000. The main memory 1090 may communicate with the main processor 1070, and may store instructions executable by the main processor 1070 as a non-transitory storage medium.

[0145] While the inventive concept has been particularly shown and described with reference to exemplary 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 inventive concept.

Claims

1. A method of operating a wireless communication device, the method comprising: receiving a wireless signal comprising a plurality of frames, wherein each frame of the plurality of frames comprises a plurality of subframes, and a current frame is initially a first frame of the plurality of frames; a) performing a correlation calculation between each subframe of the current frame and a corresponding one of a plurality of reference signals to generate a plurality of current correlation values; b) accumulating the current correlation value with the previous correlation value respectively to generate current accumulated values ​​corresponding to the multiple subframes of the current frame respectively; c) deriving a first value based on a peak value of the current accumulated value and a statistical value of the current accumulated value, and comparing the first value with a validity determination threshold adjusted according to the number of times step b) is performed; determining whether a valid synchronization signal is detected based on the comparison result; and The next frame of the plurality of frames is set as a new current frame, the current correlation value is set as a new previous correlation value, and a determination is made whether to restart to step a) based on a determination as to whether a valid synchronization signal is detected.

2. The method according to claim 1 further comprising setting a maximum accumulation quantity for performing the accumulation, in, Determining whether to restart to step a) includes: When the number of times the accumulation is performed is less than the maximum accumulation number and when the valid synchronization signal is not detected, restarting to step a); and When the number of times the accumulation is performed is less than the maximum accumulation number and when the valid synchronization signal is detected, a cell for wireless communication is identified based on the valid synchronization signal.

3. The method according to claim 1, wherein: The statistical value is the minimum value among the current accumulated values, and The first value is a ratio of a peak value to a minimum value.

4. The method according to claim 1, wherein: The statistical value is the average value of the current accumulated value, and The first value is a ratio of peak value to average value.

5. The method according to claim 1, further comprising: The validity determination threshold is adjusted based on a false alarm rate when the valid synchronization signal is detected.

6. The method according to claim 1, further comprising: The validity determination threshold is adjusted based on channel information used to receive the wireless signal.

7. The method according to claim 1, wherein: The plurality of reference signals are narrow primary synchronization signals, and Determining whether a valid synchronization signal is detected includes determining whether a valid narrow primary synchronization signal is detected from the current accumulated value.

8. The method according to claim 1, wherein: The plurality of reference signals are narrow secondary synchronization signals, and Determining whether a valid synchronization signal is detected includes determining whether a valid narrow secondary synchronization signal is detected from the current accumulated value.

9. A cell search method for a wireless communication device, comprising: receiving a wireless signal in which occurrences of each of a narrow primary synchronization signal and a narrow secondary synchronization signal are defined at preset time intervals; Setting a first maximum accumulation number for an operation of accumulating narrow primary synchronization signal correlation values, wherein the wireless signal includes a first frame and a second frame, and the first frame and the second frame include a plurality of subframes respectively; calculating a first narrow primary synchronization signal correlation value by performing a narrow primary synchronization signal correlation calculation between each subframe of the first frame and a corresponding one of a plurality of narrow primary synchronization signal reference signals; Accumulating the first narrow primary synchronization signal correlation value with previous narrow primary synchronization signal correlation values ​​respectively to generate a first accumulated value; determining whether a valid narrow primary synchronization signal is detected based on the first accumulated value; and When a first accumulation amount obtained when respectively accumulating the first narrow primary synchronization signal related values ​​to generate the first accumulation value is less than the first maximum accumulation amount, frame boundary information is obtained from the valid narrow primary synchronization signal when the valid narrow primary synchronization signal is detected.

10. The cell search method according to claim 9, further comprising: calculating a second narrow primary synchronization signal correlation value by performing a narrow primary synchronization signal correlation calculation between each subframe of the second frame and a corresponding one of the narrow primary synchronization signal reference signals when the valid narrow primary synchronization signal is not detected; and The second narrow primary synchronization signal correlation value is accumulated together with the first narrow primary synchronization signal correlation value to generate a new first accumulated value.

11. The cell search method according to claim 9, wherein: Determining whether a valid narrow master sync signal is detected includes: deriving a first validity determination threshold based on the first accumulated quantity; and Whether the valid narrow primary synchronization signal is detected is determined based on a comparison between the first accumulated value and the first validity determination threshold.

12. The cell search method according to claim 9, further comprising: Predicting a position of the narrow secondary synchronization signal based on the frame boundary information; calculating a first narrow secondary synchronization signal correlation value by performing a narrow secondary synchronization signal correlation calculation between each subframe of the first frame and a corresponding one of a plurality of narrow secondary synchronization signal reference signals based on the predicted position; and Accumulating the first narrow secondary synchronization signal correlation value with previous narrow secondary synchronization signal correlation values ​​respectively to generate a second accumulated value; and The narrow secondary synchronization signal is detected based on the second accumulated value.

13. The cell search method according to claim 12, further comprising: setting a second maximum accumulation number for accumulating the first narrow secondary synchronization signal correlation value to generate the second accumulation value, Wherein, detecting the narrow secondary synchronization signal includes: determining whether a valid narrow secondary synchronization signal is detected based on the second accumulated value; and When a second accumulated number obtained by respectively accumulating the first narrow secondary synchronization signal related values ​​to generate the second accumulated value is less than the second maximum accumulated number, cell ID information is obtained from the valid narrow secondary synchronization signal when the valid narrow secondary synchronization signal is detected.

14. The cell search method according to claim 13, wherein: Determining whether a valid narrow secondary synchronization signal is detected includes: deriving a second validity determination threshold based on the second accumulated quantity; and Whether the valid narrow secondary synchronization signal is detected is determined based on a comparison between the second accumulated value and the second validity determination threshold.

15. A wireless communication device, comprising: an antenna receiving a wireless signal including a plurality of frames in which occurrences of each of a narrow primary synchronization signal and a narrow secondary synchronization signal are defined at preset time intervals, wherein each of the plurality of frames includes a plurality of subframes; a narrow primary synchronization signal correlator configured to output a narrow primary synchronization signal correlation value by performing a correlation calculation on each of the plurality of subframes of a current frame of the plurality of frames with a corresponding one of a plurality of narrow primary synchronization signal reference signals to perform a narrow primary synchronization signal correlation calculation on the current frame; a narrow primary synchronization signal combiner configured to accumulate the narrow primary synchronization signal correlation values ​​respectively to generate first accumulated values ​​respectively corresponding to the plurality of subframes of the current frame; and a narrow primary synchronization signal controller configured to determine whether a valid narrow primary synchronization signal is detected based on the first accumulated value, and output a control signal for controlling the narrow primary synchronization signal correlator based on the determination as to whether a valid narrow primary synchronization signal is detected, Wherein, the narrow master synchronization signal controller is further configured as: Receiving a preset first maximum cumulative quantity; and When the narrow primary synchronization signal combiner performs the accumulation a number of times less than the first maximum accumulation number, frame boundary information is obtained from the valid narrow primary synchronization signal when the valid narrow primary synchronization signal is detected.

16. The wireless communication device according to claim 15, wherein: The narrow primary synchronization signal controller is further configured to control the narrow primary synchronization signal correlator to perform a narrow primary synchronization signal correlation calculation on a next frame of the plurality of frames because the valid narrow primary synchronization signal is not detected.

17. The wireless communication device according to claim 15, wherein: The narrow master synchronization signal controller is further configured to calculate a validity determination threshold based on the number of times, and perform a comparison using the first accumulated value and the validity determination threshold to determine whether the valid narrow master synchronization signal is detected.

18. The wireless communication device according to claim 15, further comprising: an input buffer configured to predict a position of the narrow secondary synchronization signal based on the frame boundary information; a narrow secondary synchronization signal correlator configured to output a narrow secondary synchronization signal correlation value by performing a narrow secondary synchronization signal correlation calculation based on the predicted position, a plurality of subframes of the current frame, and a plurality of narrow secondary synchronization signal reference signals; a narrow secondary synchronization signal combiner configured to accumulate the narrow secondary synchronization signal related values ​​respectively to generate second accumulated values ​​respectively corresponding to a plurality of subframes of the current frame; and A narrow secondary synchronization signal controller is configured to determine whether a valid narrow secondary synchronization signal is detected based on the second accumulated value, and output a control signal for controlling the narrow secondary synchronization signal correlator based on the determination as to whether a valid narrow secondary synchronization signal is detected.

19. The wireless communication device according to claim 18, wherein: The narrow auxiliary synchronization signal controller is further configured to: Receiving a preset second maximum cumulative quantity; When the narrow secondary synchronization signal combiner performs the accumulation a number of times less than the second maximum accumulation number, cell ID information is obtained from the valid narrow secondary synchronization signal when the valid narrow secondary synchronization signal is detected.

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