CN105049148B - A kind of LTE interference methods and system based on synchronizing signal - Google Patents

Abstract

The present invention discloses an LTE interference method and system based on a synchronization signal, which mainly includes two schemes: 1) It does not need to be synchronized with the base station, that is, the shielding system searches for frequency point information in the shielding area, and in the frequency point where LTE signals may exist Send one or more sets of PSS or SSS interference signals at a certain frequency at or near the point. 2) It is necessary to obtain the synchronization information of the base station, that is, search for the frequency point information of the base station in the shielded area, receive the PSS and SSS signals sent by the base station, synchronize the shielding system with the base station, and obtain the frame timing information and physical layer cell identification of the cell; According to the acquired physical layer cell identity, the shielding system generates one or more groups of PSS or SSS interference signals; the shielding system sends one or more groups of interference signals in a specific time-frequency range. The transmission power of the method and system provided by the invention is very low, has no influence on human health, does not affect the uplink channel at the same time, and has no interference to users in the non-shielding area.

Description

A kind of LTE interference method and system based on synchronization signal

technical field

The invention relates to an LTE interference method and system based on a synchronization signal, and belongs to the technical field of wireless mobile communication.

Background technique

In recent years, the problem of mobile phone leaks has become increasingly prominent. In some special occasions, such as confidential meeting rooms, government departments, and military departments, it is necessary to shield the mobile phone signal and cut off the communication between the mobile phone and the outside world to prevent information leakage; for example, in the examination room, the use of mobile phone signal jammers can effectively prevent candidates from using Cheating on wireless communication tools, etc. In order to ensure information security or meet some specific needs, mobile phone signal jammers have been widely used in daily work and life.

At present, there are many kinds of mobile phone signal jammers available on the market, with different transmission power, interference frequency bands, and coverage areas. The most common signal jammer is a power suppression jammer, which interferes with mobile phone signals by sending high-power white noise. This kind of interference technology is realized by reducing the signal-to-noise ratio of the signal received by the mobile phone. The equivalent isotropic radiation power of indoor jammers generally ranges from a dozen watts to tens of watts. In actual application scenarios, it does not meet the national "Electromagnetic Radiation Protection Regulations" and the industry's "Radiation Environmental Protection Management Guidelines - Electromagnetic Radiation Environment Impact Evaluation Methods and Standards”, long-term exposure to signal shielding environments will inevitably affect people’s health.

With the widespread deployment of LTE (Long Term Evolution, long-term evolution), LTE mobile phone signal jammers have received extensive attention. LTE mobile phone signal jamming systems are moving towards low transmission power, large interference range, good interference effect and no impact on the uplink. direction of the road.

Contents of the invention

In order to effectively reduce the impact of the jammer's transmission power on human health and increase the interference range and interference effect, the present invention provides an LTE interference method and system based on a synchronization signal. The method and system interfere with PSS (Primary Synchronization Signal , Primary Synchronization Signal) and SSS (Secondary Synchronization Signal, Secondary Synchronization Signal) as means, applicable to TD-LTE or LTE-FDD system, can play an ideal interference effect on terminals in RRC-CONNECTED or RRC-IDLE state.

The LTE synchronization signal includes a PSS signal and an SSS signal. The detection of the two signals can obtain time synchronization and frequency synchronization, and can also provide a physical layer cell identity for the terminal. In order to ensure communication, the terminal needs to synchronize with the base station through a synchronization signal, so interfering with the PSS signal and/or SSS signal can make the terminal unable to synchronize with the base station and obtain base station configuration information, and then cannot communicate, achieving the purpose of interference.

A method for interfering with LTE based on a synchronization signal, used in a system including a base station, a shielding system and a terminal, the specific implementation steps are as follows:

1) Obtain the frequency information of possible LTE signals in the base station in the target shielding area, and input it to the shielding system;

2) The shielding system generates one or more sets of interference signals that are the same as the synchronization signals sent by the base station according to the acquired frequency point information;

3) The shielding system sends interference signals to the terminal at specific time domain and frequency domain positions.

Further, the synchronization signal is a PSS signal and/or an SSS signal, and the interference signal is a PSS interference signal and/or an SSS interference signal.

Further, when the synchronization signal is a PSS signal and an SSS signal, the shielding system searches for the frequency point information of the base station in the target shielding area, receives the PSS signal and the SSS signal sent by the base station, and synchronizes the shielding system with the base station to obtain the cell The frame timing information and the physical layer cell identifier are used to generate one or more sets of PSS and SSS interference signals identical to the synchronization signal sent by the base station according to the obtained physical layer cell identifier information.

Further, from the perspective of the time domain, the interference signal sent by the shielding system and the synchronization signal sent by the base station are in the same OFDM (Orthogonal Frequency Division Multiplexing, Orthogonal Frequency Division Multiplexing) symbol (Symbol), by sending one or more groups Interference signal, so that there is a time length offset between the interference signal and the base station signal.

Further, the above time length offset includes a time offset ΔTpss of the PSS interference signal relative to the PSS signal sent by the base station, and a time offset ΔTsss of the SSS interference signal relative to the SSS signal sent by the base station.

Further, the above ΔTpss and ΔTsss are both smaller than the time length of one OFDM symbol.

Preferably, the above-mentioned ΔTpss and ΔTsss are dynamically changed, while satisfying that ΔTpss≠ΔTpss.

Further, the frequency domain position of the interference signal sent by the shielding system is the same as the frequency point of the synchronization signal sent by the base station, and the power of the interference signal sent by the shielding system received by the terminals in the target shielding area is not less than that of the synchronization signal sent by the base station power.

The present invention also provides a kind of LTE interference system based on synchronous signal, comprises following unit:

A base station information acquisition unit, configured to acquire frequency point information of the base station;

Interference signal generation unit: used to generate the same interference signal as the synchronization signal sent by the base station;

An interference signal sending unit: used to send an interference signal at a specific time-frequency domain position.

Further, the base station information acquisition unit also includes a frequency scanning unit and a receiving signal processing unit; the frequency scanning unit is used to search the frequency points of the base station in the shielded area; the receiving signal processing unit is used to realize the shielding system and The synchronization of the base station obtains the frame timing information of the cell and the cell identification information of the physical layer.

Wherein, in the case of cost saving, the frequency point information and the physical layer cell identification information may be obtained by other means without using the frequency scanning unit and the received signal processing unit, and input them to the shielding system. But the jamming signal generation unit and the sending unit are indispensable.

The interference method of the present invention can interfere with the PSS signal and the SSS signal alone, or combine them together. The present invention is not only applicable to a single-frequency single-cell system, but also applicable to communication systems of same-frequency multi-cell and multi-frequency multi-cell.

Invention advantages:

1. Compared with the power suppression shielding system, the interference method and system of the present invention have very low transmission power and will not affect human health.

2. Since the PSS and SSS signals used in the interference method of the present invention only occupy the bandwidth of 6 wireless resource blocks (ie 1.08 MHz), the bandwidth of the generated interference signal is very narrow, which facilitates cost reduction.

3. In the interference method of the present invention, the interference signal is sent in the downlink and the power of the interference signal is very low, so the performance of the uplink will not be affected.

4. After the initial synchronization between the shielding system and the base station is completed, synchronous tracking may not be performed or the time gap of synchronous tracking may be greatly increased, reducing the complexity of system design.

5. The interference method and shielding system described in the present invention have a large interference range and good interference effect.

Description of drawings

Fig. 1 is the realization flow chart in the embodiment 1 of the present invention;

Fig. 2 is the time-domain position diagram of the interference signal sent by the present invention;

FIG. 3 is a structural block diagram of an LTE interference system according to Embodiment 1 of the present invention;

FIG. 4 is a structural block diagram of an LTE interference system according to Embodiment 2 of the present invention.

Detailed ways

The implementation of the present invention is described below by examples. The implementation examples are carried out on the premise of the technical solution of the present invention, and the detailed implementation and specific operation process are given. It should be noted that, as long as there is no conflict, each embodiment and each feature in each embodiment of the present invention can be combined with each other, and the formed technical solutions are all within the protection scope of the present invention.

Embodiment one:

This embodiment is an implementation of the interference method proposed by the present invention, that is, combined use of PSS and SSS signals for interference, the shielding system needs to be synchronized with the base station, and the shielding system generates and transmits the same signal as the base station at a specific time-frequency domain position. Multiple groups of interference signals, the implementation process of this method will be described in detail below, and the implementation process is shown in FIG. 1 .

1. Shield system search frequency point information

The shielding system searches for the frequency point information of the base station in the shielded area. During the frequency sweep process, for the searched frequency point, it judges whether the correlation peak value of the synchronization signal reaches the set frequency sweep threshold. If it is greater than or equal to the threshold value, the frequency point is considered valid; otherwise, the frequency point is an invalid frequency point, and the search for the next frequency point is continued.

2. The shielding system is synchronized with the base station

The shielding system receives the synchronization information (PSS and SSS signals) sent by the base station to synchronize the shielding system with the base station, and obtain the frame timing information and physical layer cell identity of the cell

3. The shielding system generates interference signals

Generate multiple sets of PSS and SSS interference signals identical to those of the base station according to the obtained physical layer cell identification information. The specific generation method is as follows:

The PSS signal uses the Zadoff-Chu sequence, the SSS signal uses the M sequence, and the physical layer cell identifier Numbered by PSS sequence and SSS serial number jointly decide, namely:

is the physical cell identity group (0~167), are intra-group identifiers (0, 1, 2), which together form 504 different physical layer cell identifiers.

The PSS sequence d(n) is a Zadoff-Chu sequence in the frequency domain, which is generated by formula (1):

Among them, n is any integer from 0 to 61, and u is the root index. The Zadoff-Chu root sequence index u is given in Table 1.

Table 1: Root index for generating PSS sequences

The SSS sequence is a sequence of length 62 obtained by cross-concatenating two M sequences of length 31, which is generated according to formula (2):

Wherein, c ₀ (n) and c ₁ (n) are scrambling code sequences depending on the main synchronization signal; and and are scrambling code sequences obtained from different m-sequences through different cyclic shifts respectively.

4. The shielding system sends interference signals

A shielding system transmits an interfering signal in a specific range of time and frequency domains. From the time domain point of view, near the symbol (Symbol) of the PSS and SSS signals sent by the base station, multiple sets of PSS and SSS interference signals are sent, so that there is a time length offset Δt between the interference signal and the base station signal; where the time length offset Δt The size of is dynamically changing and is less than the time length of one symbol. The time domain position of the transmitted interference signal is shown in Figure 2; from the frequency domain, the frequency point of the interference signal is the same as the frequency of the PSS and SSS signals sent by the base station. The point is the same; from the perspective of the power received by the mobile phone, the power of the synchronization signal sent by the shielding system received by the mobile phone in the target shielding area is not less than the power of the synchronization signal sent by the base station.

So far, Embodiment 1 of the interference solution proposed by the present invention is completed, and users in the target shielded area can be interfered.

Embodiment 1 of the present invention also provides an LTE interference system based on a synchronization signal. FIG. 3 shows a structural block diagram of the system. In this embodiment, the frequency scanning unit and the receiving signal unit form a base station information acquisition unit, each composed The functions of the unit are as follows:

Frequency scanning unit: as in step 1 in this embodiment, it is responsible for searching the frequency points of base stations in the shielded area;

Received signal processing unit: as in step 2 in this embodiment, the main function is to realize the synchronization between the shielding system and the base station, and to obtain synchronization information and physical layer cell identification

An interference signal generation unit: as in step 3 in this embodiment, it is used to generate the same PSS and SSS interference signals as the base station;

An interference signal sending unit: as in step 4 in this embodiment, it is mainly used to send an interference signal at a specific time-frequency domain position.

Embodiment two:

This embodiment is an implementation of the interference method proposed by the present invention, that is, the SSS signal is used alone for interference, the shielding system does not need to be synchronized with the base station, and the shielding system generates and transmits the same signal as the base station at a specific time-frequency domain position. For multiple groups of interference signals, the implementation process of this method will be described in detail below.

1. Obtain the frequency point information and physical layer cell identity of the base station

Use some software or tools to search the frequency point information and physical layer cell identity information of the base station in the shielded area, determine the frequency point information and physical layer cell identity information that may have LTE signals, and input them to the shielding system.

2. The shielding system generates and transmits interference signals

The shielding system generates multiple sets of SSS interference signals identical to those of the base station based on the acquired frequency point information and physical layer cell identification, and sends interference signals at or near the frequency point at a certain frequency. From the power received by the mobile phone, the power of the synchronization signal sent by the shielding system received by the mobile phone in the target shielding area is not less than the power of the synchronization signal sent by the base station.

The LTE interference system based on the synchronization signal in this embodiment, as shown in FIG. 4 , since it does not need to be synchronized with the base station, the received signal processing unit can be omitted accordingly.

So far, the second embodiment of the interference scheme based on the present invention has been completed, and the users in the target shielded area can be shielded from interference.

The description of the present invention has been presented for purposes of illustration and description, but not exhaustive or limited to the invention in the form disclosed. Apparently, those skilled in the art can make various changes and modifications to the examples of the present invention without departing from the spirit and principle of the present invention. The embodiment was chosen and described in order to better explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention and design various embodiments with various modifications as are suited to the particular use.

Claims (5)

1. A method for LTE interference based on a synchronization signal, applicable to a system comprising a base station, a shielding system and a terminal, wherein the synchronization signal is a PSS signal and/or an SSS signal, and the interference signal is a PSS interference signal and/or an SSS interference signal, the steps are as follows: 1) Obtain the frequency information of possible LTE signals in the base station in the target shielding area, and input it to the shielding system; 2) The shielding system generates one or more sets of interference signals that are the same as the synchronization signals sent by the base station according to the acquired frequency point information; 3) The shielding system sends an interference signal to the terminal at the set time domain and frequency domain position. From the time domain, the interference signal sent by the shielding system is within the same OFDM symbol as the synchronization signal sent by the base station. By sending one or more Group interference signals, so that there is a time length offset between the interference signal and the base station signal, and the time length offset includes the time offset ΔTpss of the PSS interference signal relative to the PSS signal sent by the base station, the SSS interference signal relative to the SSS signal sent by the base station The time offset of the signal is ΔTsss, the ΔTpss and ΔTsss are both smaller than the time length of one OFDM symbol, the ΔTpss and ΔTsss are dynamically changed, and ΔTpss≠ΔTsss is satisfied at the same time. 2. the LTE interference method based on synchronous signal as claimed in claim 1, is characterized in that, when described synchronous signal is PSS signal and SSS signal, described shielding system searches the frequency point information of base station in target shielding area, Receive the PSS signal and SSS signal sent by the base station to synchronize the shielding system with the base station, obtain the frame timing information and physical layer cell identification of the cell, and generate one or more sets of synchronization signals sent by the base station according to the obtained physical layer cell identification information Same PSS and SSS interfering signals. 3. The LTE interference method based on synchronization signals as claimed in claim 1, wherein the frequency domain position of the interference signal sent by the shielding system is the same as the frequency point of the synchronization signal sent by the base station, and the frequency points in the target shielding area The power received by the terminal from the interference signal sent by the shielding system is not less than the power received by the terminal from the synchronization signal sent by the base station. 4. A kind of LTE interference system based on synchronization signal, described synchronization signal is PSS signal and/or SSS signal, and described interference signal is PSS interference signal and/or SSS interference signal, and described LTE interference system based on synchronization signal comprises The following units: A base station information acquisition unit, configured to acquire frequency point information of the base station; Interference signal generation unit: used to generate the same interference signal as the synchronization signal sent by the base station; Interference signal sending unit: used to send interference signals at specific time-frequency domain positions. From the time domain point of view, the interference signal sent by the shielding system and the synchronization signal sent by the base station are in the same OFDM symbol. By sending one or more groups of interference signals signal, so that there is a time length offset between the interference signal and the base station signal, and the time length offset includes the time offset ΔTpss of the PSS interference signal relative to the PSS signal sent by the base station, and the time offset ΔTpss of the SSS interference signal relative to the SSS signal sent by the base station. The time offset ΔTsss, the ΔTpss and ΔTsss are both less than the time length of one OFDM symbol, the ΔTpss and ΔTsss are dynamically changing, and ΔTpss≠ΔTsss is satisfied at the same time. 5. the LTE interference system based on synchronous signal as claimed in claim 4, is characterized in that, described base station information acquisition unit comprises frequency scanning unit and received signal processing unit again; Described frequency scanning unit is used for shielding area The frequency point of the base station is searched; the received signal processing unit is used to realize the synchronization between the shielding system and the base station, and obtain frame timing information and physical layer cell identification information of the cell.