CN111817814A - A 5G NR signal shielding method and system based on SSB - Google Patents

Abstract

The invention relates to a 5G NR signal shielding method and system based on SSB. The method comprises the following steps: collecting 5G NR wireless signals; acquiring a physical cell identifier by using a 5G NR wireless signal, and decoding a physical channel; generating an interference signal by using the physical cell identifier and the information obtained by decoding the physical channel; an interfering signal is transmitted to shield the 5G NR wireless signal. The system comprises a signal acquisition module, a baseband processing module and a signal transmitting module. The interference signal of the invention only aims at the downlink SSB signal, does not interfere the uplink and does not influence the normal use of the base station; the invention adopts a mode of synchronously reconstructing synchronous signals, only occupies a small amount of time-frequency resources, and has small transmitting power, no influence on body health and large effective interference distance compared with a pressing type interference method; the invention supports 5G NR multiple sub-carrier spacing configuration parameters.

Description

A 5G NR signal shielding method and system based on SSB

technical field

The invention relates to a 5G NR signal shielding method and system, which are applied to mobile terminal shielding and belong to the field of mobile communication.

Background technique

The mobile terminal shielding system can shield mobile terminals in a certain area and block their communication with the base station. At present, the 5G NR (NewRadio, which is a global 5G standard based on a new air interface design based on OFDM) system is being deployed on a large scale. In the future 5G era, the leakage problem of mobile terminals will become increasingly prominent. Information security protection in prisons, public security, government departments, confidential conference rooms and other anti-leakage places poses greater challenges.

The principle of the traditional suppression interference system is as follows: white noise signal is generated in the mobile communication frequency band, amplified by the power amplifier, and then sent to the air interface (that is, the air interface, which defines the wireless transmission specification between the base station and the mobile phone) to suppress the interference. . In order to achieve the effect of suppressing interference, the system often needs a high-gain power amplifier to increase the transmit power. This kind of system transmits power is very large, which is harmful to health and cannot meet the requirements of green environmental protection.

SUMMARY OF THE INVENTION

The present invention is oriented to the mobile terminal management and control requirements of high-security and leak-proof places, and provides a low-power, green shielding system and method for 5G NR mobile communication systems that do not damage physical health.

The technical scheme adopted in the present invention is as follows:

A 5G NR signal shielding method based on SSB, comprising the following steps:

Collect 5G NR wireless signals;

Use 5G NR wireless signals to obtain physical cell identifiers and perform physical channel decoding;

Using the physical cell identifier and the information obtained by decoding the physical channel to generate an interference signal;

Transmit interference signals to block 5G NR wireless signals.

Further, the collecting of 5G NR wireless signals includes: collecting wireless signals of all frequency bands of 5G NR in the environment, and performing down-conversion and analog-to-digital conversion processing.

Further, the obtaining the physical cell identifier by using the 5G NR wireless signal includes: searching for the primary synchronization signal PSS and the secondary synchronization signal SSS to obtain the physical cell identifier.

Further, the performing physical channel decoding includes: searching the PBCH DM-RS signal, determining the SSB index and field indication information, and obtaining field synchronization.

Further, generating the interference signal by using the physical cell identifier and the information obtained by decoding the physical channel includes:

Using the physical cell identifier, reconstruct the PSS sequence of the primary synchronization signal and the SSS sequence of the secondary synchronization signal;

Recreate the PBCH DMRS sequence by using the SSB index and the field indication information;

Combining the reconstructed primary synchronization signal PSS sequence, the reconstructed secondary synchronization signal SSS sequence and the reconstructed PBCH DMRS sequence to generate multiple reconstructed SSB sequences to form interference sequences;

The interference sequence is subjected to QPSK modulation and resource mapping to generate an interference signal.

Further, the resource mapping includes: the frequency domain position of the interference signal is consistent with the originally collected SSB signal, and the time domain position is different from the originally collected SSB signal by several OFDM symbols.

Further, the transmitting the interference signal includes: performing digital-to-analog conversion on the interference signal, up-converting and amplifying the signal, and then transmitting it to the air interface.

A 5G NR signal shielding system based on SSB using the above method, comprising:

Signal acquisition module, used to collect 5G NR wireless signals;

The baseband processing module is used to obtain the physical cell identifier by using the 5G NR wireless signal, and perform physical channel decoding to realize half-frame synchronization; use the physical cell identifier and the information obtained by decoding the physical channel to generate interference signals;

The signal transmission module is used to transmit interference signals to shield 5G NR wireless signals.

The beneficial effects of the present invention are as follows:

The present invention adopts the method of synchronously reconstructing the 5G specific physical layer signal, only needs to perform signal processing within the SSB signal bandwidth, and does not need to receive the entire frequency point bandwidth.

The present invention reconstructs the interference sequence based on the received SSB signal, and at the same time can also generate interference signals for the remaining SSBs in the SS burst, so as to achieve effective interference to the 5G multiple beam signals.

The interference signal of the present invention only occupies a small amount of time-frequency resources, and compared with the suppression interference method, the transmission power is small, the physical health is not affected, and the effective interference distance is large.

The present invention supports 5G NR flexible parameter set, and is applicable to Sub-6GHz (below 6GHz) and millimeter wave frequency bands.

Description of drawings

Figure 1 is a flow chart of the steps of the SSB-based 5G NR signal masking method.

Figure 2 is a schematic diagram of the module structure of the SSB-based 5G NR signal shielding system.

Detailed ways

In order to make the above objects, features and advantages of the present invention more clearly understood, the present invention will be further described in detail below through specific embodiments and accompanying drawings.

In the present invention, SSB refers to a synchronization signal block (Synchronization Signal and PBCH block, SSB for short), which is composed of a primary synchronization signal PSS (Primary Synchronization Signals), a secondary synchronization signal SSS (Secondary Synchronization Signals), and a physical broadcast channel PBCH (Physical Broadcast Channel). .

The SSB-based 5G NR signal shielding method of the present invention, its step flow is shown in Figure 1, including: including: collecting 5G NR wireless signals; using 5G NR wireless signals to obtain physical cell identifiers, and performing physical channel decoding; using physical cells Identify and decode the physical channel information to generate interference signals; transmit interference signals to shield 5G NR wireless signals.

The SSB-based 5G NR signal shielding system of the present invention, as shown in FIG. 2 , includes a signal acquisition module, a baseband processing module, and a signal transmission module. The signal acquisition module is responsible for collecting 5G NR wireless signals in the air interface and sending them to the baseband processing module. The baseband processing module realizes the functions of physical cell identification acquisition, physical channel decoding, and generation of interference signals (or shielded signals). The signal transmission module mixes and amplifies the interference signal and transmits it to the air interface to implement interference.

1. Signal acquisition module

The signal acquisition module receives wireless signals in all frequency bands of 5G NR in the environment, and performs down-conversion and analog-to-digital conversion processing.

Among them, down-conversion refers to the spectrum shifting of the received signal to convert it into an intermediate frequency signal; analog-to-digital conversion refers to the conversion of an analog signal into a digital signal to facilitate subsequent signal processing.

2. Baseband processing module

The baseband processing module integrates the programmable logic array FPGA to complete the sampling and processing of the intermediate frequency signal. The module includes a physical cell identity acquisition unit, a decoding unit, and an interference signal generating unit.

及物理小区标识组号

因此，物理小区标识获取单元可通过搜索PSS及SSS来获取物理小区标识。The primary synchronization signal PSS and the secondary synchronization signal SSS signal respectively carry the ID within the physical cell ID group

and physical cell identification group number

Therefore, the physical cell identity acquisition unit can acquire the physical cell identity by searching the PSS and the SSS.

After the PSS and SSS signals are determined, a PBCH DM-RS (Demodulation Reference Signal, demodulation reference signal) signal needs to be further searched. In the time domain, the symbol position of the PSS, SSS and PBCH DM-RS can be determined according to the relative positions of the PSS, SSS and PBCH DM-RS. In the frequency domain, the frequency domain distribution of the PBCH DM-RS is related to the physical cell identity, and the frequency domain offset of the PBCH DM-RS can be determined by using the obtained physical cell identity information. The decoding unit obtains SSB index information and field indication information by searching the PBCH DM-RS signal, and obtains field synchronization.

The interference signal generating unit generates the interference signal according to the information obtained by the physical cell identifier obtaining unit and the decoding unit.

The specific implementation process of the baseband processing module generating the interference signal is as follows:

否则，继续搜索下一频点。1) Spectrum scanning, searching for the primary synchronization signal PSS to correlate the acquired signal with the local PSS sequence in sequence. There are 3 types of local PSS sequences. If the correlation peak between the acquired signal and the local PSS sequence i (0≤i≤2) is greater than the specified threshold, the SSB signal is successfully found, and the current frequency has a cell. The PSS sequence used in the cell is is the sequence i, and further solve

Otherwise, continue to search for the next frequency point.

2) Continue to search for the secondary synchronization signal SSS, and the SSS signal to be collected is correlated with the local SSS sequence in sequence. There are 336 local SSS sequences in total. If the correlation peak between the collected signal and the local SSS sequence j (0≤j≤335) is the largest, it is determined that the SSS sequence of the cell is the sequence j, and the solution is further solved.

已知PBCH DM-RS在SSB中的频域偏移

进一步确定PBCH DM-RS的频域位置。3) Calculate the 5G NR physical cell identity according to formula (1)

Known frequency domain offset of PBCH DM-RS in SSB

The frequency domain location of the PBCH DM-RS is further determined.

4) Search the PBCH DM-RS signal, and the collected DM-RS signal is correlated with the local DM-RS sequence in turn. The DM-RS sequence of the SSB is the sequence k. The DM-RS signal carries SSB index i _SSB and field indication n _hf information, SSB index i _SSB indicates the index value of the current SSB in an SS burst set, field indication n _hf indicates the field where the SSB is located, and 0 indicates the SSB In the first field, 1 means that the SSB is in the second field. For frequency bands below 6GHz, the current SSB index i _SSB and half frame indication n _hf information can be determined. For frequency bands above 6GHz, only the lower 3-bit information of the current SSB index i _SSB can be determined. At this time, it is necessary to further decode the PBCH to obtain the MIB (master information block), determine the upper 3 bits of the SSB index i _SSB .

5) According to the above-mentioned information obtained in steps 1) and 2), the primary synchronization signal PSS sequence d _PSS (n) is reconstructed with reference to formula (2), and the secondary synchronization signal SSS sequence d _SSS (n) is reconstructed with reference to formula (3);

d _PSS (n)=1-2x(m) (2)

where x(m) is a sequence of m, expressed as:

x(i+7)=(x(i+4)+x(i))mod2

where the initialization sequence of x(i) is,

[x(6) x(5) x(4) x(3) x(2) x(1) x(0)]=[1 1 1 0 1 1 0]

d _SSS (n)=[1-2x ₀ ((n+m ₀ )mod127)][1-2x ₁ ((n+m ₁ )mod127)] (3)

0≤n≤127

Among them, x ₀ (n) and x ₁ (n) are m sequences respectively, which are expressed as

x ₀ (i+7)=(x ₀ (i+4)+x ₀ (i))mod2

x ₁ (i+7)=(x ₁ (i+1)+x ₁ (i))mod2

where the initialization sequence of x ₀ (i) is,

[x ₀ (6) x ₀ (5) x ₀ (4) x ₀ (3) x ₀ (2) x ₀ (1) x ₀ (0)]=[0 0 0 0 0 0 1]

where the initialization sequence of x ₁ (i) is,

[x ₁ (6) x ₁ (5) x ₁ (4) x ₁ (3) x ₁ (2) x ₁ (1) x ₁ (0)]=[0 0 0 0 0 0 1]

6) According to the above information obtained in step 4), refer to formula (4) to reconstruct the PBCH DMRS sequence, which is represented by r(m). Since 5G transmits different SSBs on multiple beams in the form of time division multiplexing, the currently parsed SSB is only one of the SS bursts. It is necessary to calculate the remaining SSBs in the SS burst through the time domain position of the current SSB and the index i _SSB . position, while recreating all PBCH DMRS of the SS burst.

Among them, c(n) is a pseudo-random sequence, which is generated by 2 m sequences of length 31:

c(n)=(x ₁ (n+N _c )+x ₂ (n+N _c ))mod2,N _c =1600

x ₁ (n+31)=(x ₁ (n+3)+x ₁ (n))mod2

x ₂ (n+31)=(x ₂ (n+3)+x ₂ (n+2)+x ₂ (n+1)+x ₂ (n))mod2

The initialization seed for c(n) is:

The initialization sequence of the x ₁ (n) sequence is:

x ₁ (0)=1, x ₁ (n)=0, n=1,...,30

where x ₂ (n) sequence initialization sequence should satisfy the following conditions:

7) Using the combination of the reconstructed primary synchronization signal PSS sequence, the reconstructed secondary synchronization signal SSS sequence and the reconstructed PBCH DMRS sequence in step 5), multiple reconstructed SSB sequences are generated to form an interference sequence.

8) Perform QPSK (Quadrature Phase Shift Keying) modulation and resource mapping on the interference sequence to generate an interference signal (or shielded signal). The SSB signals differ by several OFDM (Orthogonal Frequency Division Multiplexing) symbols.

3. Signal transmitter module

The signal transmitting module performs digital-to-analog conversion on the above-mentioned interference signal, and transmits it to the air interface after up-conversion and amplification.

Among them, analog-to-digital conversion refers to converting a digital signal into an analog signal; up-conversion refers to moving the spectrum to the radio frequency; amplification refers to amplifying the power of a wireless signal.

The specific embodiments of the present invention disclosed above and the accompanying drawings are intended to help understand the content of the present invention and implement them accordingly. Those skilled in the art can understand that various replacements can be made without departing from the spirit and scope of the present invention. , variations and modifications are possible. The present invention should not be limited to the contents disclosed in the embodiments of the present specification and the accompanying drawings, and the protection scope of the present invention is subject to the scope defined by the claims.

Claims (10)

1. a 5G NR signal shielding method based on SSB, is characterized in that, comprises the following steps: Collect 5G NR wireless signals; Use 5G NR wireless signals to obtain physical cell identifiers and perform physical channel decoding; Using the physical cell identifier and the information obtained by decoding the physical channel to generate an interference signal; Transmit interference signals to block 5G NR wireless signals. 2 . The method according to claim 1 , wherein the collecting of 5G NR wireless signals comprises: collecting wireless signals of all frequency bands of 5G NR in the environment, and performing down-conversion and analog-to-digital conversion processing. 3 . 3 . The method according to claim 1 , wherein the obtaining the physical cell identifier by using the 5G NR wireless signal comprises: searching for the primary synchronization signal PSS and the secondary synchronization signal SSS to obtain the physical cell identifier. 4 . 4 . The method according to claim 1 , wherein the performing physical channel decoding comprises: searching for a PBCH DM-RS signal, determining an SSB index and field indication information, and obtaining field synchronization. 5 . 5. The method according to claim 4, wherein the generating an interference signal by using the physical cell identifier and the information obtained by decoding the physical channel comprises: Using the physical cell identifier, reconstruct the PSS sequence of the primary synchronization signal and the SSS sequence of the secondary synchronization signal; Recreate the PBCH DMRS sequence by using the SSB index and the field indication information; Combining the reconstructed primary synchronization signal PSS sequence, the reconstructed secondary synchronization signal SSS sequence and the reconstructed PBCH DMRS sequence to generate multiple reconstructed SSB sequences to form interference sequences; The interference sequence is subjected to QPSK modulation and resource mapping to generate an interference signal. 6. method according to claim 5 is characterized in that, adopts following formula to reconstruct primary synchronization signal PSS sequence d _PSS (n) and secondary synchronization signal SSS sequence d _SSS (n): d _PSS (n)=1-2x(m), where x(m) is a sequence of m, expressed as:

x(i+7)=(x(i+4)+x(i))mod2, where the initialization sequence of x(i) is: [x(6) x(5) x(4) x(3) x(2) x(1) x(0)]=[1 1 1 0 1 1 0]; d _SSS (n)=[1-2x ₀ ((n+m ₀ )mod 127)][1-2x ₁ ((n+m ₁ )mod 127)],

0≤n≤127, in,

The identification within the physical cell identification group carried by the primary synchronization signal PSS;

The physical cell identification group number carried by the SSS signal of the secondary synchronization signal

Among them, x ₀ (n) and x ₁ (n) are m sequences respectively, which are expressed as: x ₀ (i+7)=(x ₀ (i+4)+x ₀ (i))mod2, x ₁ (i+7)=(x ₁ (i+1)+x ₁ (i))mod2, where the initialization sequence of x ₀ (i) is: [x ₀ (6) x ₀ (5) x ₀ (4) x ₀ (3) x ₀ (2) x ₀ (1) x ₀ (0)]=[0 0 0 0 0 0 1], where the initialization sequence of x ₁ (i) is: [x ₁ (6) x ₁ (5) x ₁ (4) x ₁ (3) x ₁ (2) x ₁ (1) x ₁ (0)] = [0 0 0 0 0 0 1]. 7. method according to claim 5, is characterized in that, adopts following formula to reconstruct PBCH DMRS sequence r(m):

Among them, c(n) is a pseudo-random sequence, which is generated by 2 m sequences of length 31: c(n)=(x ₁ (n+N _c )+x ₂ (n+N _c ))mod2, N _c =1600, x ₁ (n+31)=(x ₁ (n+3)+x ₁ (n))mod2, x ₂ (n+31)=(x ₂ (n+3)+x ₂ (n+2)+x ₂ (n+1)+x ₂ (n))mod2, The initialization seed for c(n) is:

The initialization sequence of the x ₁ (n) sequence is: x ₁ (0)=1, x ₁ (n)=0, n=1, . . . , 30, where x ₂ (n) sequence initialization sequence should satisfy the following conditions:

8. The method according to claim 5, wherein the resource mapping comprises: the frequency domain position of the interference signal is consistent with the originally collected SSB signal, and the time domain position is different from the originally collected SSB signal by several OFDM symbols . 9 . The method according to claim 1 , wherein the transmitting the interference signal comprises: performing digital-to-analog conversion on the interference signal, and then transmitting the interference signal to the air interface after up-conversion and amplification. 10 . 10. A 5G NR signal shielding system based on SSB using the method according to any one of claims 1 to 9, characterized in that, comprising: Signal acquisition module, used to collect 5G NR wireless signals; The baseband processing module is used to obtain the physical cell identifier by using the 5G NR wireless signal, and perform physical channel decoding to realize half-frame synchronization; use the physical cell identifier and the information obtained by decoding the physical channel to generate interference signals; The signal transmission module is used to transmit interference signals to shield 5G NR wireless signals.

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