KR102625779B1 - Method and apparatus for detecting narrowband random access channel - Google Patents

Abstract

A narrowband physical random access channel detection method and apparatus are provided. The base station receives the preamble, converts the received signal into a frequency domain signal, maps the subcarrier index to the frequency domain signal, extracts a plurality of sequences of the configuration index, and random accesses one sequence from the extracted sequences. Detected by channel signal. Then, IFFT (Inverse Fast Fourier Transform) is performed by reflecting only the subcarrier values according to the frequency hopping pattern of the sequence detected as a random access channel signal.

Description

Method and apparatus for detecting narrowband physical random access channel {Method and apparatus for detecting narrowband random access channel}

The present invention relates to channel detection, and more specifically, to a method and apparatus for detecting a narrowband physical random access channel in a narrowband Internet of things (IoT) system.

In a wireless communication system, PRACH (physical random access channel) is a physical channel for transmission of a random access preamble, which is the first step in the random access (RA) process in which a terminal requests connection establishment with a network. Channel). That is, the time-frequency resource through which the RA preamble is transmitted is called PRACH. The base station broadcasts system information indicating which time-frequency resources can be used for RA preamble transmission to all terminals. The RA preamble refers to the UE's RA request information transmitted to the network through PRACH. There are a total of 64 available RA preambles within one network, and how these 64 preambles can be generated is broadcast through system information.

During the random access process, the terminal selects a preamble and transmits it to the base station, and the base station transmits a response message such as preamble ID information indicating the received preamble and timing information (TA: Timing Advance) for adjusting the uplink timing. . The terminal then transmits a message containing RACH information such as uplink resource allocation information for message transmission and temporary terminal ID information (radio network temporary identify (T-RNTI)) to the base station.

Recently, research on the Internet of Things has become more active. The Internet of Things refers to a network infrastructure in which all objects, including humans, are connected to wired and wireless networks to organically collect and share information and cooperate with each other. Standardization is underway for narrow band (NB) IoT (Internet of things), a new wireless transmission technology to realize LPWA (Low Power Wide Area) networks. An effective method for detecting random access channels in such narrowband IoT systems is required.

The technical problem to be solved by the present invention is to provide a method and device that can effectively detect a preamble transmitted through a physical random access channel in a narrowband IoT system.

Additionally, the technical problem to be solved by the present invention is to provide a method and device for estimating the timing offset of a detected preamble sequence.

A method according to a feature of the present invention is a method for detecting a random access channel in a narrowband system, comprising: a base station receiving a preamble and converting the received signal into a frequency domain signal; mapping a subcarrier index to the frequency domain signal and extracting a sequence of a plurality of component indices; detecting one sequence as a random access channel signal from the extracted sequences; and performing IFFT (Inverse Fast Fourier Transform) by reflecting only subcarrier values according to the frequency hopping pattern of the sequence detected with the random access channel signal.

According to an embodiment of the present invention, a preamble sequence transmitted through a physical random access channel in a narrowband IoT system can be detected and a timing offset estimate of the detected preamble sequence can be provided.

In addition, it is possible to detect all sequences used in random access physical channels at once, and by setting the detection level for the average value of the entire sequence, the probability of false alarm and miss detection can be reduced.

In addition, by using only the subcarrier values actually used for the detected sequence and nulling all remaining subcarrier values to 0, noise other than the actual sequence is reflected in the timing estimation to prevent performance deterioration. You can.

Figure 1 is a diagram showing a random access preamble symbol group.
Figure 2 is a diagram showing a transmission and reception process for transmitting and receiving a random access preamble.
Figure 3 is a diagram showing the structure of a physical random access channel detection device according to an embodiment of the present invention.
Figure 4 is a diagram showing a CP section and FFT area according to an embodiment of the present invention.
Figure 5 is an exemplary diagram showing subcarrier demapping according to an embodiment of the present invention.
Figure 6 is an exemplary diagram showing power combining according to a frequency hopping pattern according to an embodiment of the present invention.
Figure 7 is a flowchart of a random access channel detection method for performing preamble sequence detection and timing estimation according to an embodiment of the present invention.
Figure 8 is a structural diagram of a random access channel detection device according to another embodiment of the present invention.

Below, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein.

In order to clearly explain the present invention in the drawings, parts that are not related to the description are omitted, and similar parts are given similar reference numerals throughout the specification.

Throughout the specification and claims, when a part is said to 'include' a certain component, this means that it may further include other components rather than excluding other components, unless specifically stated to the contrary.

Throughout the specification, terminal refers to user equipment (UE), a mobile terminal (MT), a mobile station (MS), an advanced mobile station (AMS), and a high-reliability mobile station ( It may refer to high reliability mobile station (HR-MS), subscriber station (SS), portable subscriber station (PSS), access terminal (AT), etc., and may also refer to UE, MT, MS , may include all or part of the functions of AMS, HR-MS, SS, PSS, AT, etc.

In addition, the base station (BS) is an advanced base station (ABS), a high reliability base station (HR-BS), a node B, an evolved node B, eNodeB or eNB), access point (AP), radio access station (RAS), base transceiver station (BTS), mobile multihop relay (MMR)-BS, repeater that acts as a base station (relay station, RS), relay node (RN) that acts as a base station, advanced relay station (ARS) that acts as a base station, high reliability relay station (high reliability relay station) that acts as a base station , HR-RS), small base station [femto base station (femoto BS), home node B (HNB), home eNodeB (HeNB), pico base station (pico BS), metro base station (metro BS), micro base station ( micro BS), etc.] may refer to all or part of eNode, ABS, Node B, eNodeB, eNB, AP, RAS, BTS, MMR-BS, RS, RN, ARS, HR-RS, small base station, etc. It may also include the functions of

Hereinafter, a method and device for detecting a narrowband physical random access channel according to an embodiment of the present invention will be described.

Figure 1 is a diagram showing a random access preamble symbol group.

In a narrowband (NB) IoT (Internet of things) system, the narrowband physical random access channel, that is, NPRACH (Narrowband physical random access channel), is a physical channel through which the terminal transmits a random access preamble to access the network. am. NPRACH consists of four symbol groups, and each symbol group consists of a CP (Cyclic Prefix) and five symbols, as shown in Figure 1 attached. Here, CP has a length of 2048 Ts or 8192 Ts, and five symbols can have the same length of 8192 Ts. Here, Ts means a specific time unit. The preamble format can be divided into two formats depending on the CP length, and the corresponding information is provided from the L1 control parameter.

Table 1 below shows random access preamble parameters.

NPRACH's preamble transmission applies 3.75kHz subcarrier spacing and consists of single subcarrier transmission.

Each symbol group of NPRACH performs frequency hopping, and when transmitting the first preamble symbol group, the first subcarrier index is provided by L1 control, and the subcarriers of the remaining three preamble symbol groups by frequency hopping. The index is calculated according to Equation 1 below, and the remaining three preamble symbol groups are transmitted continuously.

내에서만 호핑하도록 패턴이 정해지며, i번째 심볼 그룹의 서브캐리어 위치

는 다음과 같다. NPRACH's preamble is

The pattern is set to hop only within the subcarrier location of the ith symbol group.

is as follows:

은 MAC(Media access control) 계층에서 선택된

값에 의해서 하기의 수학식 1과 같이, 정해진다. 이때,

은

중 하나의 값을 갖는다.First subcarrier location

is selected at the MAC (Media access control) layer.

The value is determined as shown in Equation 1 below. At this time,

silver

It has one value.

는 NPRACH에 할당된 첫 번째 서브캐리어의 주파수 위치이며, L1 제어 파라미터로 주어진다.

는 NPRACH에 할당된 서브캐리어 개수이며, 예를 들어, 12, 24, 36, 48 중 하나의 값을 가질 수 있으며, 이 역시 L1 제어 파라미터로 주어진다.

is the frequency position of the first subcarrier assigned to NPRACH, and is given as the L1 control parameter.

is the number of subcarriers allocated to NPRACH, and can have, for example, one of the following values: 12, 24, 36, or 48, which is also given as an L1 control parameter.

When repeated transmission occurs in NPRACH preamble transmission, f(t) must be obtained from Equation 1 above to obtain the subcarrier index of the first symbol group of repeated transmission. Here, the pseudo random sequence c(n) used is defined as a gold sequence of length 31, and the output sequence c(n) of length Mpn is defined as follows.

이고, Nc=1600이며, 첫번째 m-시퀀스는

로 초기화되며, 두번째 m-시퀀스는

으로 표현할 수 있다. 이때

로서 셀 고유 ID 값인

은 L1 제어 파라미터로 주어진다. here,

, Nc=1600, and the first m-sequence is

It is initialized with , and the second m-sequence is

It can be expressed as At this time

As the cell's unique ID value,

is given as the L1 control parameter.

Figure 2 is a diagram showing a transmission and reception process for transmitting and receiving a random access preamble.

As shown in Figure 2, for transmission of NPRACH, a random access preamble, a transmitter (e.g., terminal) generates a preamble symbol (S1), and uses an L1 controller (not shown) to transmit the preamble symbol group. ) maps the generated preamble symbol to the subcarrier corresponding to the subcarrier index input from ). Then, as described above, four consecutive preamble symbol groups are generated by mapping each preamble symbol to a subcarrier corresponding to a subcarrier index according to the subcarrier hopping pattern calculated according to Equation 1 (S2). In NPRACH transmission, the number of repetitions of these four preamble symbol groups can be up to 128, and when applying preamble symbol group repetition, the subcarrier index of the first symbol group repeated is pseudo-random hopping ( pseudo-random hopping is applied.

Inverse discrete fourier transform (IDFT) (e.g., 8192-IDFT) is performed on the generated preamble symbol group to generate a time-domain signal. Then, a CP (e.g., one of the two types of CP in Table 1) is inserted into the time domain signal (S3). Afterwards, four preamble symbol groups are transmitted continuously. And, depending on whether or not it is repeated, the preamble symbol group is transmitted the corresponding number of times.

The receiving end (e.g., base station) receives the signal transmitted in this way, removes the CP from the received signal, and performs DFT (e.g., 8192-DFT) to convert the time-domain signal into a frequency-domain signal. (S4). Subcarrier demapping is performed on the frequency domain signal to extract the frequency domain signal of the preamble sequence, that is, the preamble symbol group (S5). The maximum correlation is calculated from the extracted preamble symbol group, and the index and timing offset information of the transmitted preamble sequence are extracted by measuring the phase difference of the received symbols (S6).

When the terminal connects to the network through NPRACH, it randomly selects a random preamble sequence from among the NPRACH resources allocated during the NPRACH transmission period indicated in the system information and transmits the NPRACH signal, that is, the preamble, as described above. The base station receives preambles transmitted by one or more terminals, and since the maximum resource allocated to NPRACH is, for example, 48, it can detect up to 48 preamble sequences.

In an embodiment of the present invention, a preamble sequence transmitted using a frequency hopping technique is detected using a single tone in a narrowband IoT system, and the timing offset of the sequence is estimated.

Figure 3 is a diagram showing the structure of a physical random access channel detection device according to an embodiment of the present invention.

The physical random access channel detection device 10 according to an embodiment of the present invention includes an RF reception processing unit 11, a detection unit 12, and a control unit 13, and the detection unit 12 includes a sequence detection unit 121 and a timing Includes an offset estimation unit 122.

The RF reception processing unit 11 receives and processes signals through an antenna, for example, receives and processes signals from two reception antennas, Antenna 0 and Antenna 1. The RF reception processing unit 11 may be named an RF reception block (narrowband RF block, NBRFB) of the narrowband IoT system.

The detection unit 12 detects a random access sequence and estimates the initial uplink timing offset according to the signal provided from the RF reception processing unit 11. The detection unit 12 may be named a physical random access channel detection block (narrowband random access detection block, NBAB).

The output signal output from the detection unit 12 is transmitted to the control unit 13, and the control unit 13 receives the output signal for each sequence index. The control unit 13 may be named a narrowband IoT system control block (narrowband control block, NBCB).

The detection unit 12 receives the NPRACH configuration index used in the corresponding base station from the control unit 13, and determines the NPRACH format according to the CP length and the NPRACH transmission section from the signal provided from the RF reception processing unit 11. Transmission frame information and subcarrier information containing the preamble are extracted. Here, the NPRACH format can be known based on Table 1 depending on whether the CP length is 2048 or 8192. And the detection unit 12 receives NPRACH frequency offset information and cell ID information, which is RA channel band information used within one cell, and detects the random access sequence.

Specifically, in order to detect a random access sequence, that is, the NPRACH preamble sequence, the sequence detector 121 removes the CP length from the time domain signal of the signal received for each antenna and samples for performing FFT (Fast Fourier Transform). Save it. For example, save 8192 samples to perform an 8192-point FFT.

Figure 4 is a diagram showing a CP section and FFT area according to an embodiment of the present invention.

As shown in the attached FIG. 4, the received time domain signal consists of a CP section and 5 symbol sections (NPRACH symbol sections). When the NPRACH format is format 0, the CP has a length of 2048Ts, and in format 1, the CP has a length of 8192Ts. It has length. The CP section is removed from the received time domain signal, and the area (5 symbol sections) where FFT is performed is stored.

Thereafter, the sequence detector 121 converts the CP-removed time domain signal into a frequency domain signal by performing FFT processing (e.g., 8192-point FFT). At this time, the NPRACH symbol section is composed of 5×8192Ts, so combining can be performed after performing FFT on each 8192Ts time domain signal constituting the NPRACH symbol section. Alternatively, FFT may be performed after combining 5 symbols from the time domain signal.

Next, the detector 12 performs subcarrier demapping on the frequency domain signal obtained through FFT processing to extract the frequency domain signal of the preamble sequence, that is, the preamble symbol group.

Figure 5 is an exemplary diagram showing subcarrier demapping according to an embodiment of the present invention.

As illustrated in FIG. 5, the frequency domain signal obtained through FFT processing is mapped to a subcarrier index, and then, starting from the control parameter (nprachPRB) calculated from the NPRACH configuration index (PRBIndex) provided by the control unit 13. For example, 48 sequences are extracted.

Each of the 48 extracted sequences is combined. Specifically, the power of the corresponding sequence is obtained according to a frequency hopping pattern determined for each input slot and then combined. This is performed for four consecutive slots, and if there is repeated transmission, combining is performed for each frequency hopping pattern for four consecutive input slots per repetition number. The frequency hopping patterns for the 12 sequences are as follows.

Based on the frequency hopping pattern above, in the 12 sequences, the first sequence 0 calculates the cumulative sum of the powers of sequence 1 in the second slot, sequence 7 in the third slot, and sequence 6 in the fourth slot. The first sequence 1 calculates the cumulative sum of the powers of sequence 0 in the second slot, sequence 6 in the third slot, and sequence 7 in the fourth slot. In this way, based on the frequency hopping pattern, the cumulative sum of all powers during the four consecutive slot sections from the first 0 to 11 sequences is obtained.

If there is repeated transmission, the first sequence of the repeated transmission is determined by the cell ID parameter based on the gold sequence (31-gold sequence), so the sequence of the first input slot of the repeated transmission is obtained and the above math is performed based on this sequence. The cumulative sum is obtained according to the hopping pattern according to Equation 4, and the cumulative sum of all powers during four consecutive slot sections is obtained.

Figure 6 is an exemplary diagram showing power combining according to a frequency hopping pattern according to an embodiment of the present invention.

For example, if the first input slot of repeated transmission is 3, then according to the frequency hopping pattern {3, 2, 8, 9}, sequence number 2 is received in the second slot, sequence number 8 is entered in the third slot, and sequence number 9 is received in the fourth slot. Calculate the cumulative sum of the powers of this sequence.

Based on this method, the cumulative sum from the first sequence 0 to sequence 11, which was transmitted twice repeatedly, is as follows.

In this way, the cumulative sum of power for 12 sequences is calculated according to the frequency hopping pattern for sequences 0-11.

To set the detection level for detecting a sequence, the average value of the 12 sequences combined as described above (or the average value of a total of 48 preamble sequences, for example, the maximum resource allocated to NPRACH) is derived. Specifically, a specific position point (e.g., a point that is more than a set % (e.g., 40%) of the average value) of the average value of the final cumulative sum of the 12 sequences is set as the detection level, and a value greater than the detection level is set. A sequence with is detected as an NPRACH signal. The specific location point for the average can be set to a value that can increase the detection probability through simulation appropriate to the cell environment.

In setting the detection level, the detection level may be a specific position point for the average of the maximum and minimum values of the 12 combined sequences, or may be a specific position point for the average by sequentially selecting a plurality of maximum and minimum values. Alternatively, it may be a specific location point for the average of all 12 combined sequences.

Meanwhile, if there is no NPRACH signal, a false alarm may occur. A failure warning indicates, for example, that a preamble was detected but was incorrectly detected due to noise. For this purpose, the sequence with a value greater than N% (TBD) of the minimum value among the cumulative sum of 12 sequences is set to be the detection target.

By tracking all 12 sequences according to the frequency hopping pattern, it is possible to detect all sequences used in NPRACH at once, and by setting the detection level for the average value of the entire sequence, the probability of failure warning and miss detection can be significantly lowered. You can.

The timing offset estimation unit 122 estimates the timing offset of the detected sequence as described above. For this purpose, an IFFT (Inverse FFT) process is performed on the sequence detected with the NPRACH signal. Among the 12 sequences, N-point IFFT is performed with the values of the received subcarrier positions for the sequence detected as the NPRACH signal, that is, the random access received signal, by the procedure described above.

If IFFT is performed based on the values of all 12 sequences for timing estimation, noise other than the actual sequence is reflected in the timing estimation, degrading performance. Therefore, only the four subcarrier values corresponding to the frequency hopping of the sequence detected by the sequence detection procedure are reflected, all others are nulled to 0, and IFFT is performed.

For example, assuming that sequence number 3 was detected as a random access received signal and was transmitted as a single, the frequency hopping pattern PRACH_SC_HOPPING[12][4] ={{0, 1, 7, 6}, {1, 0, 6, 7}, {2, 3, 9, 8}, {3, 2, 8, 9}, {4, 5, 11, 10}, {5, 4, 10, 11}, {6, 7, 1, 0}, {7, 6, 0, 1}, {8, 9, 3, 2}, {9, 8, 2, 3}, {10, 11, 5, 4}, {11, 10, 4, 5} }, only the values of subcarriers 3, 2, 8, and 9 are reflected, the values of the remaining subcarriers are nulled to 0, and IFFT is performed.

As another example, assuming that sequence 0 is detected as a random access reception signal and transmitted twice repeatedly, only the values of subcarriers 0 - 1 - 7 - 6 - 3 - 2 - 8 - 9 are reflected and the values of the remaining subcarriers are reflected. The value is nulled to 0 and then IFFT is performed. In this process, if subcarriers are overlapped due to repeated transmission, the subcarrier value divided by the number of overlapping subcarriers (overlap count), that is, the normalized subcarrier value, is reflected for IFFT.

As a result of performing IFFT by reflecting only the subcarrier value corresponding to the frequency hopping of the detected sequence and nulling all the rest to 0, each power is measured, and an index with the maximum power among the measured powers is used. is determined as the timing estimate. The timing estimate thus determined is reported to L1.

By using only the subcarrier values actually used for the detected sequence, nulling all remaining subcarrier values to 0, and then performing IFFT, it is possible to prevent noise other than the actual sequence from being reflected in the timing estimation, thereby degrading performance. there is.

Figure 7 is a flowchart of a random access channel detection method for performing preamble sequence detection and timing estimation according to an embodiment of the present invention.

The base station receives the preamble, which is the NPRACH signal, from the terminal during the NPRACH transmission period, removes the CP from the received signal, and performs FFT (S100).

Subcarrier demapping is performed on the FFT-processed signal to extract a preamble symbol group (S110). As described above, the frequency domain signal obtained through FFT processing is mapped to a subcarrier index, a number of sequences are extracted from the NPRACH configuration index (PRBIndex), and power combining of the extracted sequences is performed for each frequency hopping pattern. Do it (S120).

The average value of the combined sequences is derived, a detection level is set based on this (S130), and a sequence with a value greater than the detection level is detected using the NPRACH signal (S140).

Afterwards, a timing offset estimation procedure is performed. Specifically, an IFFT process is performed on the sequence detected with the NPRACH signal (S150). At this time, only the subcarrier value corresponding to the frequency hopping of the sequence detected by the sequence detection procedure is reflected, all others are nulled to 0, and IFFT is performed.

For the result of performing the IFFT, each power is measured (S160), and the subcarrier index with the maximum power among the measured powers is determined as the timing estimate (S170). This timing offset estimation procedure (S150 to S170) can be performed for each detected sequence.

Figure 8 is a structural diagram of a random access channel detection device according to another embodiment of the present invention.

As shown in the attached FIG. 8, the random access channel detection device 100 according to an embodiment of the present invention includes a processor 110, a memory 120, and a transceiver 130.

The processor 110 may be configured to implement the methods described in FIGS. 3 to 7 above.

The memory 120 is connected to the processor 110 and stores various information related to the operation of the processor 110. The memory 120 may store instructions to be executed by the processor 110 or may load instructions from a storage device (not shown) and temporarily store them.

The processor 110 may execute instructions stored or loaded in the memory 120. The processor 110 may be configured to perform the function of the detection unit of FIG. 3.

The processor 110 and the memory 120 are connected to each other through a bus (not shown), and an input/output interface (not shown) may also be connected to the bus.

The transceiver unit 130 may be configured to perform the function of the RF reception processor of FIG. 3.

The embodiments of the present invention are not implemented only through the devices and/or methods described above, but can be implemented through programs for realizing functions corresponding to the configuration of the embodiments of the present invention, recording media on which the programs are recorded, etc. This implementation can be easily implemented by an expert in the technical field to which the present invention belongs based on the description of the embodiments described above.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of the present invention by operators using the basic concept of the present invention defined in the following claims are also possible. It falls within the scope of rights.

Claims (10)

A method for detecting a random access channel in a narrowband system, comprising:
A base station receiving a preamble and converting the received signal into a frequency domain signal;
mapping a subcarrier index to the frequency domain signal and extracting a plurality of sequences from the frequency domain signal based on the configuration index;
detecting one sequence as a random access channel signal from the plurality of extracted sequences; and
Performing IFFT (Inverse Fast Fourier Transform) by reflecting only subcarrier values according to the frequency hopping pattern of the sequence detected with the random access channel signal.
Detection method including. According to paragraph 1,
The step of detecting with the random access channel signal is,
A detection method, wherein a sequence having a value greater than a detection level from the plurality of sequences is detected as a random access channel signal, and the detection level is set based on the power of the plurality of sequences, According to paragraph 2,
The step of detecting with the random access channel signal is,
Obtaining a cumulative sum based on power for each of the plurality of sequences; and
Setting the detection level based on the cumulative sums obtained for each sequence
Detection method, including, According to paragraph 3,
The step of obtaining the cumulative sum is,
A detection method, for each of the plurality of sequences, obtaining the powers of a subcarrier corresponding to a frequency hopping pattern in each of a plurality of consecutive slot sections, and summing the obtained powers to obtain the cumulative sum; According to paragraph 3,
The detection level is set based on the average of the maximum and minimum values of cumulative sums obtained based on the power of the plurality of sequences, or is set based on the average of a plurality of maximum values and a plurality of minimum values among the cumulative sums. , or a detection method set based on the average of the cumulative sums. According to paragraph 1,
The step of performing the IFFT is,
Among the subcarriers of the sequence detected by the random access channel signal, only the subcarrier values according to the frequency hopping pattern are reflected, the values of the remaining subcarriers are nulled to 0, and then the IFFT is performed, Detection method. According to paragraph 1,
After performing the IFFT,
Measuring power for each subcarrier based on the result of performing the IFFT, and determining the index of the subcarrier with the maximum power among the measured powers as a timing estimate.
A detection method further comprising: A device for detecting a random access channel in a narrowband system, comprising:
Transmitter and receiver; and
processor
Including,
The processor converts a signal received through the transceiver into a frequency domain signal;
mapping a subcarrier index to the frequency domain signal and extracting a plurality of sequences from the frequency domain signal based on the configuration index;
detecting one sequence as a random access channel signal from the plurality of extracted sequences; and
A detection device configured to perform an operation of performing IFFT (Inverse Fast Fourier Transform) by reflecting only subcarrier values according to the frequency hopping pattern of the sequence detected with the random access channel signal. According to clause 8,
When performing a detection operation using the random access channel signal, the processor is configured to detect a sequence having a value greater than a detection level from the plurality of sequences as a random access channel signal,
The processor is further configured to obtain a cumulative sum based on power for each of the plurality of sequences and set the detection level based on the cumulative sums obtained for each sequence, a detection device; According to clause 9,
When obtaining the cumulative sum, the processor acquires the powers of subcarriers corresponding to the frequency hopping pattern in each of a plurality of consecutive slot sections for each of the plurality of sequences, and adds the obtained powers to the cumulative sum. It is configured to obtain,
The detection level is set based on the average of the maximum and minimum values of cumulative sums obtained based on the power of the plurality of sequences, or is set based on the average of a plurality of maximum values and a plurality of minimum values among the cumulative sums. , or a detection device set based on the average of the cumulative sums.

Images