Santhanakrishnan Anand

An Analytical Model for Primary User Emulation Attacks in Cognitive Radio Networks

In this paper, we study the denial-of-service (DoS) attack on secondary users in a cognitive radio network by primary user emulation (PUE). Most approaches in the literature on primary user emulation attacks (PUEA) discuss mechanisms to deal with the attacks but not analytical models. Simulation studies and results from test beds have been presented but no analytical model relating the various parameters that could cause a PUE attack has been proposed and studied. We propose an analytical approach based on Fentons approximation and Markov inequality and obtain a lower bound on the probability of a successful PUEA on a secondary user by a set of co-operating malicious users. We consider a fading wireless environment and discuss the various parameters that can affect the feasibility of a PUEA. We show that the probability of a successful PUEA increases with the distance between the primary transmitter and secondary users. This is the first analytical treatment to study the feasibility of a PUEA.

Detecting Primary User Emulation Attacks in Dynamic Spectrum Access Networks

In this paper, we present an analytical model as well as a practical mechanism to detect denial of service (DoS) attacks on secondary users in dynamic spectrum access (DSA) networks. In particular, we analyze primary user emulation attacks (PUEA) in cognitive radio networks without using any location information and therefore can do away with dedicated sensor networks. We present an analysis using Fentons approximation and Walds sequential probability ratio test (WSPRT) to detect PUEA. Simulation results demonstrate that it is possible to keep the probability of success of PUEA low, while still keeping the probability of missing the return of the primary low as well.

Mitigating primary user emulation attacks in dynamic spectrum access networks using hypothesis testing

We present a Neyman-Pearson composite hypothesis test (NPCHT) and a Walds sequential probability ratio test (WSPRT) to detect primary user emulation attacks (PUEA) in cognitive radio networks. Most approaches in the literature on PUEA assume the presence of underlying sensor networks for localization of the malicious nodes. There are no analytical studies available in the literature to study PUEA in the presence of multiple malicious users in fading wireless environments. We present an NPCHT and WSPRT based analysis to detect PUEA in fading wireless channels in the presence of multiple randomly located malicious users. We show that there is a range of network radii in which PUEA are most successful. Results also show that for the same desired threshold on the probability of missing the primary, WSPRT can achieve a probability of successful PUEA 50% less than that obtained by NPCHT.

Performance analysis of channelized cellular systems with dynamic channel allocation

We present an analytical model to compute the blocking probability in channelized cellular systems with dynamic channel allocation. We model the channel occupancy in a cell by a two-dimensional (2D) Markov chain, which can be solved to obtain the blocking probability in each cell. We apply our analytical model to linear highway systems with and without lognormal shadowing and then extend it to 2D cellular systems with lognormal shadowing. We show that, for linear highway systems, distributed dynamic channel-allocation schemes perform similarly to the centralized dynamic channel-allocation schemes in terms of blocking probability. However, for 2D cellular systems, the improvement in the performance is significant and the reduction in the blocking probability in systems with distributed dynamic channel allocation is by almost one order of magnitude, when compared to that in systems with centralized dynamic channel allocation. In practice, our analysis of linear highway systems is applicable to Digital European Cordless Telephony (DECT) and that of 2D cellular systems is applicable to global systems for mobile communications (GSM).

Performance analysis of IEEE 802.11 DCF with stochastic reward nets

In this paper, we present a performance study to evaluate the mean delay and the average system throughput of IEEE 802.11-based wireless local area networks (WLANs). We consider the distributed co-ordination function (DCF) mode of medium access control (MAC). Stochastic reward nets (SRNs) are used as a modelling formalism as it readily captures the synchronization between events in the DCF mode of access. We present a SRN-based analytical model to evaluate the mean delay and the average system throughput of the IEEE 802.11 DCF by considering an on–off traffic model and taking into account the freezing of the back-off counter due to channel capture by other stations. We also compute the mean delay suffered by a packet in the system using the SRN formulation and by modelling each station as an M/G/1 queue. We validate our analytical model by comparison with simulations. Copyright

Impact of Primary User Emulation Attacks on Dynamic Spectrum Access Networks

Primary user emulation attack (PUEA) is a denial of service (DoS) attack unique to dynamic spectrum access (DSA) networks. While there have been studies in the literature to detect and mitigate PUEA, the impact of PUEA on the performance of secondary networks has seldom been studied. In this paper, we analyze how PUEA affects call dropping and delay in secondary networks carrying both real-time traffic and non-real-time traffic. Numerical results indicate that PUEA can increase the number of dropped calls by up to two orders of magnitude and can increase the mean delay by up to a factor larger than two. We then evaluate the performance of secondary networks that deploy the protocols which we proposed previously to mitigate PUEA. Our protocols reduce the number of dropped calls by up to one order of magnitude. Our protocols are also shown to exhibit almost the same delay performance as that of a system with no PUEA, for low malicious traffic load. When malicious traffic load is high, our protocols provide an improvement on the delay performance by up to 54%.

Robust Spectrum Decision Protocol against Primary User Emulation Attacks in Dynamic Spectrum Access Networks

We propose a spectrum decision protocol resilient to primary user emulation attacks (PUEA) in dynamic spectrum access networks. PUEA is a type of denial-of-service attack that can severely interfere with the spectrum sensing process and unfairly deprive legitimate secondary users of spectrum access. In this paper, we present a robust spectrum decision protocol that can mitigate PUEA using individual spectrum decisions made by secondary nodes in the network. In order to enable each secondary node to make an individual spectrum decision to detect PUEA, we first characterize the received power at good secondary user. This is done by using a flexible log-normal sum approximation. The received power thus characterized is used to determine the probability of successful PUEA on each secondary user, which is used to develop the proposed protocol. Simulation results demonstrate that the proposed protocol can significantly reduce the probability of successful PUEA under Byzantine attacks (i.e., when the malicious users intentionally provide false spectrum decisions), while still following the spectrum evacuation etiquette.

On the Secrecy Capacity of Fading Cognitive Wireless Networks

In this paper, we compute the primary exclusive region (PER) and the secrecy capacity at a primary receiver in a fading cognitive radio network. We consider Rayleigh fading and log-normal shadowing. We also study the effect of secrecy capacity on the PER. We show that log-normal shadowing and Rayleigh fading can degrade the PER by about 40% and the secrecy capacity by about 70%.

Performance analysis of voice/data cellular CDMA with SIR-based admission control

In this paper, we analyze the performance of a signal-to-interference ratio (SIR)-based admission control strategy on the uplink in cellular code-division multiple-access (CDMA) systems with voice and data traffic. Most studies in the current literature to estimate CDMA system capacity with both voice and data traffic do not take into account admission control based on SIR constraints. Here, we present an analytical approach to evaluate the outage probability for voice traffic, the average system throughput, and the mean delay for data traffic in a voice/data CDMA system, which employs an SIR-based admission control. We make two main approximations in the voice call outage analysis-one based on the central limit theorem (CLT) and the other based on the Fentons method. We apply the Fentons method approximation to compute the retransmission probability and the mean delay for data traffic, and the average system throughput. We show that for a voice-only system, a capacity improvement of about 30% is achieved with the SIR-based admission control as compared with the code availability-based admission control. For a mixed voice/data system with 10 Erlangs of voice traffic, an improvement of about 40% in the mean delay for data is shown to be achieved. Also, for a mean delay of 50 ms with 10 Erlangs of voice traffic, the data Erlang capacity improves by about 50%.

Performance Analysis of Dynamic Spectrum Access Networks under Primary User Emulation Attacks

Primary user emulation attack (PUEA) is a denial of service (DoS) attack unique to dynamic spectrum access (DSA) networks. While there have been studies in the literature to detect and mitigate PUEA, the impact of PUEA on the call blocking and call dropping probabilities of users in secondary networks has not been studied. We present the first analysis to study the impact of PUEA on the secondary users in terms of call blocking and call dropping. We propose a three dimensional continuous time Markov chain (3D-CTMC) to model the channel occupancy in DSA networks. We use the 3D-CTMC to determine the call blocking and call dropping probabilities for secondary users. We validate our analysis with simulations. Results indicate that while PUEA does not affect the call blocking probability, it can increase the call dropping probability of secondary users by more than one order of magnitude. We also evaluate the call dropping performance of some of our previously proposed protocols to mitigate PUEA. We show that our protocols can improve the call dropping performance by about 40% for high traffic loads of malicious users and can provide almost the same performance as that of a system with no PUEA, when the malicious user traffic is low.