Showing papers by "Devendra Jalihal published in 2017"

Performance of p-Norm Detector in Cognitive Radio Networks with Cooperative Spectrum Sensing in Presence of Malicious Users

Abstract: A cognitive radio network (CRN) with a cooperative spectrum sensing scheme is considered. This CRN has a primary user and multiple secondary users, some of which are malicious secondary users (MSUs). Energy detection at each SU is performed using a -norm detector with , where corresponds to the standard energy detector. The MSUs are capable of perpetrating spectrum sensing data falsification (SSDF) attacks. At the fusion center (FC), an algorithm is used to suppress these MSUs which could be either an adaptive weighing algorithm or one of the following: Tietjen-Moore (TM) test or Peirce’s criterion. This is followed by computation of a test statistic (TS) which is a random variable. In this paper, we assume TS to have either a Gamma or a Gaussian distribution and calculate the threshold accordingly. We provide closed-form expressions of probability of false alarm and probability of miss-detection under both assumptions. We show that Gaussian assumption of TS is more suited in presence of an SSDF attack when compared with the Gamma assumption. We also compare the detection performance for various values of and show that along with the Gaussian assumption is the best amongst all the cases considered.

Optimal frame synchronization over a finite state Markov channel

Abstract: We study a problem of sequential frame detection over a finite state Markov channel (FSMC). We consider an asynchronous framework where a sync frame of length N symbols is transmitted uniformly over a large interval of known size A slots. In this setup, we study the scaling needed of the sync frame length N with the asynchronism interval length A for error-free frame synchronization. We study the problem when channel state information (CSI) is known at the transmitter and the receiver, and compute a synchronization threshold, α, that relates the average sync frame length N and A as N > log 2 (A)/α for asymptotic frame synchronization. Our discussion includes the description of a variable length and adaptive code word for FSMC that achieves the optimal delay performance.

A General Framework for Asynchronous Communication

Abstract: We study a problem of sequential frame detection in an asynchronous framework, where a single frame of length $N$ slots is transmitted uniformly in a large interval of known size $A$ slots. In this setup, we seek to characterize the scaling needed of $N$ and the channel (input) parameters for asynchronous optimal frame synchronization. We note that the framework permits a natural trade-off between $N$ and $\alpha $ , where $\alpha $ is the synchronization threshold of the channel (usually parameterized by the channel input). We present a general framework that permits this trade-off and then characterize the scaling needed of both $N$ and $\alpha $ as a function of the asynchronism period $A$ . Finally, we apply our results to the AWGN channel as an illustration.