Paper reading assignment
By Girish Bangalore Ramesh, SJSU:010120240

Wireless sensor networks are used to acquire the physical data from the sensors. Wireless network devices have to be authenticated and there location has to be to clearly tracked. Earlier to distinguish between the physical locations, spatial uncorrelation property of the channels was used. The broadcast nature of the wireless medium is vulnerable to Sybil attacks. The researchers have found out a new attack against the existing systems. The main idea of this attack is to create a virtual multipath channel which cannot be detected and the receiver is made to believe that is has the same characteristics as that of specified channel chosen by the receiver. The administrator …show more content…
The responses from the impulses are estimated by analyzing the training sequence. Virtual multipath is created by applying the original signal to some sort of change in phase and amplitude and later add them up to get the aggregated fake signal. The hacker introduces a second transmitter at the receiver to confuse the target. At the receiver end the received symbols is represented by y=h*x+n. Here convolution operation takes place, convolution is the method a compare to impulses, here we add ‘n’ as it is noise. The most challenging part for the attacker is to obtain weights, initially the length of Xa is L+M-1, which gets changed as Va which will be L+(L+M-1). To defend against these attacks the receiver uses two different training sequence to estimate the impulse and sends two training sequence, for which the attacker has to solve both the weights w1 and w2. These weights do not necessarily help the same channel estimation. Thus there will be a change of estimated responses and at the helper can indicate the existence of threats caused from the virtual multipath attack. The parameters dhelp is measured against the threshold the helper activity is used to find if any attack