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EP-4738734-A1 - METHOD AND APPARATUS FOR JAMMING DETECTION IN POWER LINE COMMUNICATIONS

EP4738734A1EP 4738734 A1EP4738734 A1EP 4738734A1EP-4738734-A1

Abstract

A method and a system for detecting jamming in a power line communication network, the system comprising a legitimate transmitter A, which sends messages to a legitimate receiver B and a jamming device which injects artificial malicious signals/noise into the transmission between A and B, generating DoS attacks; the method comprising the steps of estimating the transmitted samples to compare the noise free communication versus the jammed one; calculating the BER of a series of samples and plotting BER vs added noise power values curves; and analysing these curves to detect the presence of jamming and related channel characteristics.

Inventors

  • OMRI, AYMEN
  • HERNÁNDEZ FERNÁNDEZ, Javier

Assignees

  • Iberdrola, S.A.

Dates

Publication Date
20260506
Application Date
20241031

Claims (12)

  1. A communication method for jamming detection which comprises the steps of: - establishing a communication between a transmitter ( A ) and a receiver ( B ); - estimating, in a first transmitted symbol ( n = 0), a complex channel gain ( h ^ k , 0 A − B ) between A and B, defined by: h ^ k , 0 A − B = h k , 0 A − B + e k , 0 A − B wherein e k , 0 A − B is defined as: e k , 0 A − B = n k , 0 B x k , 0 A − B being n k , 0 B the complex noise sample; - sending a transmitted sample ( x k , n A − B ) adding an added noise signal ( W l B ), comprising a set of values of amplitude represented by I; - obtaining a received sample (( y k , n A − B ); - determining a detected sample ( x ^ k , n A − B ) from the received sample ( y k , n A − B ) and the estimated complex channel gain ( h ^ k , 0 A − B ) using channel equalization; - determine a reference BER curve without jamming between the transmitted sample ( x k , n A − B ) and the detected sample ( x ^ k , n A − B ) for multiple values of amplitude of the added noise signal; - testing a transmitted signal for jamming detection by: • sending a testing transmitted sample ( x k , n A − B ) adding the added noise signal ( W l B ); • obtaining a testing detected sample ( x ^ k , n A − B ) • determine a testing BER curve between the transmitted sample and the testing detected sample for each value of amplitude of the added noise signal; • compare the reference BER curve with the testing BER curve: ∘ if both match, there is no jamming; and ∘ if both are different, there is jamming.
  2. The method according to claim 1, wherein the communication established is a power line communication.
  3. The method according to claim 1, wherein the symbols are transmitted using an OFDM scheme.
  4. The method according to claim 1, wherein 4-QAM Modulation is used.
  5. The method according to claim 1, further comprising a step of calculating a signal-to-jamming-plus-noise ratio (SJNR) by: γ k , n = P A H k , n A − B P J H k , n J − B z k , n J − B + N k , n B wherein, with a null added noise signal ( W l B ): y k , n A − B = P A h k , n A − B x k , n A − B + P J h k , n J − B z k , n J − B + N k , n B and N sc is a number of subcarriers with index k, N symb is a number of symbols transmitted with index n, P A is a transmit signal power of A; P J is a jamming signal power, h k , n X − B is a channel gain of the link, X -B, X ∈ {A,J }, H k , n X − B is a squared magnitude value of the channel gain h k , n x − B , X ∈ { A,J }, N k , n B , is the environment additive noise received at B, and z k , n J − B is the jamming signal.
  6. The method according to claim 1, wherein the PLC channels are assumed to be Rayleigh fade channels and H ¯ k , n X − B defined by: H ¯ k , n X − B f k d X − S = exp − 2 a 0 + a 1 f k a 2 d X − B wherein, f k is the frequency of the subcarrier k, d X-B is the distance between X, X ∈ {A, J } and B, a 0 , a 1 and a 2 are attenuation parameters of the PLC signal related to the PLC environment under consideration.
  7. The method according to claim 1, wherein the reference BER curve is linear when the added noise signal ( W l B ) is between 40 dBµV and 120 dBµV.
  8. The method according to claim 7, wherein the testing BER curve, wherein there is jamming, is constant when the added noise signal ( W l B ) is less than an attenuated jamming signal power P J H ¯ k , n J − A .
  9. The method according to claim 8, wherein the attenuated jamming signal power P J H ¯ k , n J − A is obtained as the intersection between an asymptotic line coincident with the constant value of the testing BER curve and the reference BER curve.
  10. The method according to claim 7, wherein the constant value of the testing BER curve decreases when the distance between the jamming attack and the receiver (B) increases.
  11. The method according to claim 7, wherein the testing BER curve, wherein there is a variable jamming, is variable and no linear when the added noise signal ( W l B ) is between 40 dBµV and 120 dBµV.
  12. A communication system for detecting jamming comprising: - a transmitter (A); - a receiver (B); - a communication network between the transmitter (A) and the receiver (B); and - a processing unit configured to carry out the steps of the method according to claims 1 to 11 to detect a jamming device (J) connected to the same communication network and configured to produce DoS attacks by the injection of an artificial signal or noise in the communication network.

Description

OBJECT OF THE INVENTION The present invention relates to power line communication, particularly, to a method and apparatus for jamming detection in communications systems. Thus, it is an object of the invention a method and apparatus for jamming detection in power line communications that allows the detection of the jamming signals by analyzing a bit error rate (BER) variation. BACKGROUND ART In the initial stages, power lines were designed to transfer electricity in the 50-60 Hz frequency range from a limited number of generators, or sources, to many sinks, or consumers. It is a known fact that some of the strongest buildings ever constructed are electricity transmission towers and lines. Although PLC technology has historically had very few uses, there is now a chance that it may be widely acknowledged as an alternative mean of data transfer. The need to deliver digital phone, video, and Internet data within the home is growing as broadband connectivity inevitably becomes available. Although installing specialty wiring across communities and homes is one possibility, it is costly and time-consuming. Along with many other advantages, PLC technology makes it possible to employ the widely used power distribution infrastructure currently in place to give high-speed networking capabilities. Due to this PLC is a cost-efficient communication solution that supports a wide range of applications, such as data transmissions, home automation, smart metering, grid monitoring, and vehicular communications. However, one of the main challenges this technology faces is that PLC are susceptible to malicious attacks from illegitimate parties physically that are connected to the same power line network, such as Denial of Service (DoS) attacks. This may have strong negative impacts such as the interruption of the communications or altering the functioning of the connected devices. Considering this phenomenon, one of the challenges that PLC research faces is to develop strategies to study this kind of attacks to try to anticipate them if possible and solve them as soon as possible to reduce their impact. Currently, in the literature a few studies have been published regarding the study of the effects of jamming attacks on PLC systems, evaluating the Probability Density Function (PDF) of the instantaneous Signal-to-Jamming-plus-Noise Ratio (SJNR) and the instantaneous Signal-to-Noise Ratio (SNR). In other works, attacks simulations are performed by injection of Additive White Gaussian Noise (AWGN) to develop detection techniques based in Cumulative Sum (CUSUM) or even artificial intelligence approaches such as implementation of neural networks. In the patent ES2605105T3, a method for reducing jamming in communication line or network based in the procedure automatically detects the interferences analyzing parameters such as the SNR or the BER. However, these procedures analyzing the instantaneous value of the BER lack accuracy, because an increase in this parameter can be caused by other reasons other than jamming attacks, such as channel attenuation or the presence of additive noise. Considering this, proposing an efficient solution to detect jamming attacks in an accurate way is of high importance. DESCRIPTION OF THE INVENTION The invention consists of a system and method for jamming detection for communications systems, preferably power line communication systems. The system consists of a power line communication scenario in which there is a legitimate transmitter (A) which is sending messages to a legitimate receptor (B), using Nsc subcarriers in the presence of a potential malicious interference device (J) connected to that same communication network. This jammer J has the capability of producing DoS attacks by using a malicious interference method which implies the injection of an artificial signal or noise in the transmission link between A and B. The power line communication method, which could use 4-QAM Modulation, starts with establishing a power line communication between a transmitter (A) and a receiver (B) using Nsc subcarriers. Thus, the received signal at B can be expressed as follows: yk,nA−B=PAhk,nA−Bxk,nA−B+PJhk,nJ−Bzk,nJ−B+nk,nB wherein Nsc is the number of subcarriers with index k, Nsymb is a number of symbols transmitted represented as n, xk,nA−B is a transmitted sample, zk,nJ−B is a jamming signal, PA is a transmit signal power of A, PJ is a jamming signal power, hk,nX−B is a channel gain of the link, X -B, X ∈ {A, J }, and nk,nB is the additive noise received at B. Then, in the method of the invention for each subcarrier k, a complex channel gain ( h^k,0A−B) is estimated in a first transmitted symbol (n = 0). In such a case, the estimated complex channel gain ( h^k,0A−B) between A and B would be defined by: h^k,0A−B=hk,0A−B+ek,0A−B wherein ek,0A−B is defined as: ek,0A−B=nk,0Bxk,0A−B being nk,0B the environment additive noise received at 8 during the channel estimation performed on a first symbol (n = 0). A