Cross-Layer Jamming Detection and Mitigation in Wireless Broadcast Networks


Wireless communication systems are often susceptible to the jamming attack where adversaries attempt to overpower transmitted signals by injecting a high level of noise. Jamming is difficult to mitigate in broadcast networks because transmitting and receiving are inherently symmetric operations: A user that possesses the key to decode a transmission can also use that key to jam the transmission. We describe a code tree system that provides input to the physical layer and helps the physical layer circumvent jammers. In our system, the transmitter has more information than any proper subset of receivers. Each receiver cooperates with the transmitter to detect any jamming that affects that receiver. In the resulting system, each benign user is guaranteed to eliminate the impact of the attacker after some finite number of losses with arbitrarily high probability. We show that any system that relies on only using spreading code, and no other physical factors, to mitigate jamming must use at least j+1 codes, where j is the number of jammers. We then propose an optimized scheme that is power-efficient: Each transmission is sent on at most 2j+1codes simultaneously.


Existing System


In existing approaches a particular coding scheme, the BBC code, such that when used with indelible marks, an energy-limited jammer cannot interfere with the message transmission indefinitely. Another system proposed the uncoordinated frequency-hopping protocol, in which the transmitter seeks to finish its transmission before a jammer can find out on which frequency band the signal was transmitted. Follow-up studies have sought to extend the concept to other spreading techniques and to incorporate variable length of spreading code for faster decoding.



In the uncoordinated frequency-hopping scheme, the authors relied on the assumption that a jammer cannot timely detect the frequency band on which a packet of multiple bits is transmitted.

The effectiveness of jamming and the difficulty of differentiating jamming from congestion have previously been discussed, but no solutions were proposed to traverse the jammed area.

Proposed System

In this project, we present a scheme that allows a receiver to detect jamming by observing that a secondary message is received without the primary message. We then present a keying scheme that allows the transmitter to cooperate with the receiver to isolate the set of jammers from the set of benign users. Finally, we develop a technique called tree remerging to optimize our keying scheme so that a transmitter can group benign receivers together and let that group share one spreading code, thereby providing satisfactory quality of service to the receivers without requiring higher total transmission power.



Our approach is different from these schemes in that any transmitter–receiver pair in our proposed jamming mitigation technique shares prior-agreed keys and spreading codes.

Our protocol does not require regular feedback from receivers. however, our broadcast transmitter does need to be able to receive jamming report from receivers occasionally.

Our protocol adopts time-varying spreading codes in order to prevent attackers from learning a spreading code by correlating messages over time












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