The capacity region of an asynchronous system with two sources and two receivers is analyzed. The capacity region is first derived for a general discrete memoryless channel. The result is then applied to a random acce...
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ISBN:
(纸本)142440505X
The capacity region of an asynchronous system with two sources and two receivers is analyzed. The capacity region is first derived for a general discrete memoryless channel. The result is then applied to a random access system in which sources may either transmit information-bearing symbols or idle (empty) symbols in each time slot. The capacity region for this random access system is compared to the corresponding queueing stability region and it is demonstrated that the two regions do not coincide. This comparison is the primary contribution of our work; our result is a deviation from all previous results on the relation between information-theoretic capacity and queueing stability for random access systems
This paper compares the performance of parametric and non-parametric sequential change detection algorithms for detecting in-band wormholes in wireless ad hoc networks. The algorithms considered are the non-parametric...
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This paper compares the performance of parametric and non-parametric sequential change detection algorithms for detecting in-band wormholes in wireless ad hoc networks. The algorithms considered are the non-parametric cumulative sum (NP-CUSUM) and the repeated sequential probability ratio test (R-SPRT). Theoretical performance of the two is compared using metrics that take into account the algorithms' repeated nature, and the advantage of the parametric method is illustrated. On the other hand, connections between the parametric and non-parametric methods are made in the proposed worst case adversary model, where the non-parametric method is shown to be more robust to attack strategy changes. Experimental evaluation of wormhole detection schemes based on the two algorithms is presented. This work has implications for both the theoretical understanding and practical design of wormhole detection schemes based on parametric and nonparametric change detection algorithms.
In this paper, we identify the security and privacy issues specific to wireless health monitoring devices and describe solutions for protecting wireless communications against side channel attacks and in particular tr...
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In this paper, we identify the security and privacy issues specific to wireless health monitoring devices and describe solutions for protecting wireless communications against side channel attacks and in particular traffic analysis attacks. This process takes place by means of data obfuscation and modifications of communication protocol architectures in order to limit exposed information of system architecture to potential attackers. Initial network simulations of the proposed methods show the feasibility of these methods.
We consider secret key (SK) generation by two terminals, each of which observes an i.i.d. source which is correlated with the other; the two sources are jointly Gaussian with known distribution. The terminals are then...
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ISBN:
(纸本)9781424422562
We consider secret key (SK) generation by two terminals, each of which observes an i.i.d. source which is correlated with the other; the two sources are jointly Gaussian with known distribution. The terminals are then allowed to communicate with each other, possibly interactively in many rounds and without rate restrictions, over a noiseless two-way public channel. Randomization is permitted at each terminal. The goal is for the terminals to generate a SK comprising discrete common randomness which is concealed from an eavesdropper that has access to the public interterminal communication. We establish that this maximum rate of SK generation, i.e., SK capacity, is, as expected, the per-symbol mutual information I of the correlated sources. Our main technical contribution is a new scheme for achieving SK capacity using structured codes. In our scheme, vector quantization at rate R nats/source symbol of the source at terminal 1 is performed by employing nested lattice codes with dithering. Then, a SK is generated by the terminals from the quantized random sequence at terminal 1 and the (unquantized) Gaussian source at terminal 2, using both lossy and lossless data compression techniques. Our algorithm, using a rate-R lattice quantizer, achieves a maximum SK rate of 1/2 log 1/(e -2I +(1-e -2I )e -2R ), which tends to the SK capacity I with increasing R. Thus, our result also specifies the associated tradeoff between quantization rate R and the maximum achievable SK rate. This tradeoff is shown to be optimum among a certain restricted class of schemes for SK generation that involve quantization at rate R of a Gaussian source at one terminal.
We address the problem of non-cooperative random access of two nodes randomly transmitting packets to a single common receiver. We assume infinite buffer capacities and consider a general multi-packet reception channe...
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We address the problem of non-cooperative random access of two nodes randomly transmitting packets to a single common receiver. We assume infinite buffer capacities and consider a general multi-packet reception channel that allows packet captures in the presence of multiple simultaneous transmissions. For separate cases of saturated or possibly emptying packet queues, we specify the random access transmission strategies in cooperative and non-cooperative equilibrium to optimize the achievable or stable throughput rates, transmission energy and delay costs. We follow a game-theoretic approach to compare the non-cooperative performance of selfish nodes with full cooperation in random or scheduled access. Finally, we present extensions to random access with each packet addressed to multiple receivers
In this paper, we consider a two-step decentralized control problem with two agents which are not co-located. The first agent is located at the source of a disturbance, it can measure the disturbance with high accurac...
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ISBN:
(纸本)1424401704;9781424401703
In this paper, we consider a two-step decentralized control problem with two agents which are not co-located. The first agent is located at the source of a disturbance, it can measure the disturbance with high accuracy and it can perform local actuation, while communicating with the second agent via a Gaussian channel with a prescribed signal to noise ratio. What remains of the disturbance, after the control action of the first agent, will hit the second agent after a fixed delay. The second agent has noisy measurements as well as the information conveyed through the communication channel to decide on the best strategy to reduce the effects of the remaining disturbance. The control design paradigm is to minimize a quadratic cost combining the control power of the first agent and the final effect of the disturbance at the second agent. Such a framework can be viewed as an extension of the well known Witsenhausen's counter-example which did not include a communication channel. In the absence of a channel, Hans Witsenhausen has shown, by means of an example, that nonlinear strategies outperform the best linear strategy. This result is not obvious because the framework is linear and Gaussian, and the cost is quadratic. In this paper, we give an example illustrating that Witsenhausen's conclusion holds for our framework where a communication channel is present. We provide numerical results showing that, for a large range of the signal to noise ratio at the channel, nonlinear strategies strongly out-perform the best linear strategies
A set of terminals that observe correlated data seek to compute functions of the data using interactive public communication. At the same time it is required that this communication, observed by an eavesdropper, does ...
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ISBN:
(纸本)9781467325790
A set of terminals that observe correlated data seek to compute functions of the data using interactive public communication. At the same time it is required that this communication, observed by an eavesdropper, does not reveal the value of a private function of the data. In general, the private function and the functions computed by the terminals can be all different. We show that a class of functions are securely computable if and only if the conditional entropy of data given the value of private function is greater than the least rate of interactive communication required for an appropriately chosen multiterminal source coding task. A single-letter formula is provided for this rate in special cases.
In this paper, we study the problem of joint scheduling and rate control in wireless networks, when each transmitter has a finite amount of data traffic to deliver to its corresponding receiver. Our objective is to mi...
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In this paper, we study the problem of joint scheduling and rate control in wireless networks, when each transmitter has a finite amount of data traffic to deliver to its corresponding receiver. Our objective is to minimize the time required to deliver the total data traffic. The scheduling decisions take into account the constraints of the physical layer through the well-known physical interference model. First, we consider a time-slotted system. We provide an optimal solution through a graph-theoretic model, where the minimum-length scheduling problem is formulated as finding a shortest path on a single source directed acyclic graph. Next, due to the complexity of the discrete time problem, we simplify it in two dimensions: (i) we map it to a continuous time problem, and (ii) we restrict the set of feasible scheduling and rate control decisions that can be employed. We finally obtain an optimal scheduling and rate control policy of this simplified problem.
A microwave synthetic aperture radar (SAR) exploits coherent target-return processing to achieve an along-track spatial resolution better than its antenna's difFraction limit. It also uses its range resolution cap...
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