The application of ultra-wideband (UWB) technology to low-cost short-range communications presents unique challenges to the communications engineer. The impact of the US FCC’s regulations and the characteristics of the low-power UWB propagation channels are explored, and their effects on UWB hardware design are illustrated. This tutorial introduction includes references to more detailed explorations of the subject.

Abstract—In this paper, we study the performance of the IEEE 802.11 MAC protocol under a range of jammers that covers both channel-oblivious and channel-aware jamming. We study two channel-oblivious jammers: a periodic jammer that jams deterministically at a specified rate, and a memoryless jammer whose signals arrive according to a Poisson process. We also develop new models for channel-aware jamming, including a reactive jammer that only jams non-colliding transmissions and an omniscient jammer that optimally adjusts its strategy according to current states of the participating nodes. Our study comprises of a theoretical analysis of the saturation throughput of 802.11 under jamming, an extensive simulation study, and a testbed to conduct real world experimentation of jamming IEEE 802.11 using GNU Radio and USRP platform. In our theoretical analysis, we use a discrete-time Markov chain analysis to derive formulae for the saturation throughput of IEEE 802.11 under memoryless, reactive and omniscient jamming. One of our key results is a characterization of optimal omniscient jamming that establishes a lower bound on the saturation throughput of 802.11 under arbitrary jammer attacks. We validate the theoretical analysis by means of Qualnet simulations. Finally, we measure the real-world performance of periodic and memoryless jammers using our GNU radio jammer prototype.

Abstract — In this paper, we address the problem of countering the control channel jamming in wireless communication systems. Targeting control traffic on a system like GSM (e.g., BCCH channel) leads to smart attacks that are four orders of magnitude more efficient than blind jamming. We propose several schemes based on coding theory and its applications that can counter both external and internal attackers (traitors). We introduce a T-(traitor) resilient scheme that requires less than control information retransmissions and guarantees delivery of control information against any coalition of traitors. The proposed scheme also allows the identification of the traitors. I.

On the base of the estimator variance analysis we present a classification for a number digital chaos communication schemes and conventional spread spectrum techniques, which allows the qualitative comparison of the behaviour of the systems under the presence of additive white Gaussian noise on the channel. The classification results in a ranking and shows that the conventional stored-reference technique outperforms all analyzed chaotic schemes, which reach at most the characteristics of transmitted-reference techniques. 1 1. INTRODUCTION In recent years a steadily growing interest in chaos for cryptography and communications can be observed in research. In this paper we will focus on the communication aspect, i.e. the influence of properties of non-ideal channels on several chaos communication schemes. After first attempts to use synchronized chaos, which where affected already by slight noise disturbances, correlation-based methods were proposed in literature, working also in noisy...

In this paper new binary sequence families F k of period 2 n −1 are constructed for even n and any k with gcd(k, n) = 2 if n/2 is odd or gcd(k, n) = 1 if n/2 is even. The distribution of their correlation values is completely determined. These families have maximum correlation 2 n/2+1 + 1 and family size 2 3n/2 +2 n/2 for odd n/2 or 2 3n/2 +2 n/2 −1 for even n/2. The construction of the large set of Kasami sequences which is exactly the F k with k = n/2 + 1 is generalized.

The aim of this paper is to propose an adaptive method for suppressing wideband interferences in spread spectrum (SS) communications. The proposed method is based on the time--frequency representation of the received signal from which the parameters of an adaptive time-varying interference excision filter are estimated. The approach is based on the generalized Wigner--Hough transform as an effective way to estimate the instantaneous frequency of parametric signals embedded in noise. The performance of the proposed approach is evaluated in the presence of linear and sinusoidal FM interferences plus white Gaussian noise in terms of SNR improvement factor and bit error rate (BER).

Abstract. In this paper, for an even integer n ≥ 4 and any positive integer k with gcd(n/2, k) = gcd(n/2 − k,2k) = d being odd, a class of p-ary codes C k is defined and their weight distribution is completely determined, where p is an odd prime. As an application, a class of nonbinary sequence families is constructed from these codes, and the correlation distribution is also determined. 1.

This paper presents a simple local medium access control protocol, called Jade, for multi-hop wireless networks with a single channel that is provably robust against adaptive adversarial jamming. The wireless network is modeled as a unit disk graph on a set of nodes distributed arbitrarily in the plane. In addition to these nodes, there are adversarial jammers that know the protocol and its entire history and that are allowed to jam the wireless channel at any node for an arbitrary (1 − ɛ)-fraction of the time steps, where 0 <ɛ<1 is an arbitrary constant. We assume that the nodes cannot distinguish between jammed transmissions and collisions of regular messages. Nevertheless, we show that Jade achieves an asymptotically optimal throughput if there is a sufficiently dense distribution of nodes.

In this paper we study the distribution properties of d-FCSR sequences. These sequences have ecient generators and have several good statistical properties. We show that for d = 2 the number of occurrences of an xed size subsequence diers from the average number of occurrences by at most a small constant times the square root of the average.

Frequency-hopping (FH) spread-spectrum techniques employ sequences with Hamming correlation properties meeting suitable criteria. In this correspondence novel families of FH sequences having optimal auto- and cross-correlation properties with respect to the well-known Lempel-Greenberger bound are developed through combinatorial product type constructions. This provides us new optimal families of FH sequences with widely available values of fundamental parameters. A similar construction technique is also applied to one of combinatorial designs, called difference systems of sets, leading to comma-free codes with reasonable redundancy. 1