An array of a large number of LEDs will be widely used in future indoor illumination systems. In this paper, we investigate the problem of rendering uniform illumination by a regular LED array on the ceiling of a room. We first present two general results on the scaling property of the basic illumination pattern, i.e., the light pattern of a single LED, and… (More)
Light-emitting diodes (LEDs) will play a major role in future indoor illumination systems. In general, the generalized Lambertian pattern is widely used as the radiation pattern of a single LED. In this letter, we show that the illuminance distribution due to this Lambertian pattern, when projected onto a horizontal surface such as a floor, can be well… (More)
—Reducing the number of tag collisions is one of the most important issues in RFID systems, as collisions induce inefficiency. This paper presents a mechanism of grouping of tags via a bit mask, quick tag estimation by a pilot frame and near optimal binary tree-based collision resolution with a frame. Performance analysis and simulation results show that… (More)
Motivated by a recently introduced HIMMO key distribution scheme, we consider a modification of the noisy polynomial interpolation problem of recovering an unknown polynomial f (X) ∈ Z[X] from approximate values of the residues of f (t) mod-ulo a prime p at polynomially many points t taken from a short interval.
In this paper we introduce HIMMO as a truly practical and lightweight collusion-resistant key predistribution scheme. The scheme is reminiscent of Blundo et al's elegant key predistribution scheme, in which the master key is a symmetric bivariate polynomial over a finite field, and a unique common key is defined for every pair of nodes as the evaluation of… (More)
We consider a two polynomials analogue of the polynomial interpolation problem. Namely, we consider the Mixing Modular Operations (MMO) problem of recovering two polynomials <i>f</i> ∈ Z<sub><i>p</i></sub>[<i>x</i>] and <i>g</i> ∈ Z<sub><i>q</i></sub>[<i>x</i>] of known degree, where <i>p</i> and <i>q</i> are two (un)known positive integers,… (More)
This paper introduces a new key establishment scheme aiming at fully collusion-resistant identity-based symmetric-key agreement. In an identity-based pairwise key agreement scheme, a Trusted Third Party (TTP) manages the system and securely provides any node, e.g., Alice or Bob, with private keying materials. Alice can generate a pairwise key with Bob given… (More)
Motivated by a recently introduced HIMMO key predistribution scheme, we investigate the limits of various attacks on the polynomial interpolation problem with mixed modular operations and hidden moduli. We firstly review the classical attack and consider it in a quantum-setting. Then, we introduce new techniques for finding out the secret moduli and… (More)