University of Electro-Communications

About: University of Electro-Communications is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Laser & Robot. The organization has 8041 authors who have published 16950 publications receiving 235832 citations. The organization is also known as: UEC & Denki-Tsūshin Daigaku.

Statistical inference under multiterminal data compression

Abstract: This paper presents a survey of the literature on the information-theoretic problems of statistical inference under multiterminal data compression with rate constraints. Significant emphasis is put on problems: (1) multiterminal hypothesis testing, (2) multiterminal parameter estimation and (3) multiterminal pattern classification, in either case of positive rates or zero rates. In addition, the paper includes three new results, i.e., the converse theorems for all problems of multiterminal hypothesis testing, multiterminal parameter estimation, and multiterminal pattern classification at the zero rate.

Ballistic thermal conductance of a graphene sheet

Abstract: We derive a formula to calculate the ballistic thermal conductance of a two-dimensional system directly from the dispersion relations of phonons and electrons. We apply the method to a graphene and investigate both the temperature and the Fermi energy dependences of the ballistic thermal conductance. The ballistic thermal conductance per unit length of a graphene becomes isotropic from the threefold rotational symmetry. In the intrinsic graphene where the Fermi energy crosses the Dirac point, the thermal conductance of electrons increases in proportion to ${T}^{2}$ with temperature, while the phonon conductance increases in proportion to ${T}^{1.5}$ due to the quadratic dispersion relation of the out-of-plane acoustic mode and prevails over the electron-derived conductance irrespective of temperature. As the Fermi energy is moved from the Dirac point for the gated graphenes, the thermal conductance of electrons increases monotonically and the temperature dependence changes from a ${T}^{2}$ dependence in the intrinsic graphene to a $T$-linear one at low temperatures. The electron thermal conductance of the gated graphenes dominates over the phonon contribution at low temperatures.

Two-user communication channels

Abstract: A discrete memoryless channel with two inputs and two outputs, called a two-user channel, is studied under the communication situation where only separate messages are allowed to be sent between two source-user pairs. An outer bound to the capacity region is obtained by a method similar to that used by the author for the broadcast channel. Two extreme cases of two-user channels are discussed: separate channels and incompatible channels. Degraded two-user channels are introduced and studied in detail; in particular, an achievable region is obtained by combining two regions that correspond to the two different modes of transmission. This idea is extended to the general two-user channel where an achievable region for the general channel is obtained by random coding arguments.

Accountable-subgroup multisignatures: extended abstract

Abstract: Formal models and security proofs are especially important for multisignatures: in contrast to threshold signatures, no precise definitions were ever provided for such schemes, and some proposals were subsequently broken.In this paper, we formalize and implement a variant of multi-signature schemes, Accountable-Subgroup Multisignatures (ASM). In essence, ASM schemes enable any subgroup, S, of a given group, G, of potential signers, to sign efficiently a message M so that the signature provably reveals the identities of the signers in S to any verifier.Specifically, we provide:The first formal model of security for multisignature schemes that explicitly includes key generation (without relying on trusted third parties);A protocol, based on Schnorr's signature scheme [33], that is both provable and efficient:Only three rounds of communication are required per signature.The signing time per signer is the same as for the single-signer Schnorr scheme, regardless of the number of signers.The verification time is only slightly greater than that for the single-signer Schnorr scheme.The signature length is the same as for the single signer Schnorr scheme, regardless of the number of signers.Our proof of security relies on random oracles and the hardness of the Discrete Log Problem.