Topic
Communication channel
About: Communication channel is a research topic. Over the lifetime, 137411 publications have been published within this topic receiving 1715077 citations. The topic is also known as: communication channel & communications channel.
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TL;DR: The physical configuration and the protocol of Fasnet are described and channel utilization for the condition of continuously queued sources is given and Mechanisms to control the access of various traffic types are described.
Abstract: Fasnet is an implicit token-passing, local-area network aimed at supporting high data rates and carrying a wide mix of traffic (data, voice, video, and facsimile). Transmission is unidirectional with stations attaching to the medium passively via directional couplers. A link consists of two lines, one to carry traffic in each direction. Unidirectional transmission provides the potential for efficient operation at high data rates, while the passive medium provides the potential for high reliability. We describe the physical configuration and the protocol and give channel utilization for the condition of continuously queued sources. Mechanisms to control the access of various traffic types are described. Finally, the interconnection of multiple Fasnets is studied for one particular configuration, a ring.
241 citations
TL;DR: 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.
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.
240 citations
TL;DR: This work proves that the mutual information is a concave function of a matrix which itself is a quadratic function of the precoder matrix, and proposes a parameterized iterative algorithm for finding optimal linear precoders to achieve the global maximum of the mutual Information.
Abstract: We study the design optimization of linear precoders for maximizing the mutual information between finite alphabet input and the corresponding output over complex-valued vector channels. This mutual information is a nonlinear and non-concave function of the precoder parameters, posing a major obstacle to precoder design optimization. Our work presents three main contributions: First, we prove that the mutual information is a concave function of a matrix which itself is a quadratic function of the precoder matrix. Second, we propose a parameterized iterative algorithm for finding optimal linear precoders to achieve the global maximum of the mutual information. The proposed iterative algorithm is numerically robust, computationally efficient, and globally convergent. Third, we demonstrate that maximizing the mutual information between a discrete constellation input and the corresponding output of a vector channel not only provides the highest practically achievable rate but also serves as an excellent criterion for minimizing the coded bit error rate. Our numerical examples show that the proposed algorithm achieves mutual information very close to the channel capacity for channel coding rate under 0.75, and also exhibits a large gain over existing linear precoding and/or power allocation algorithms. Moreover, our examples show that certain existing methods are susceptible to being trapped at locally optimal precoders.
240 citations
Patent•
15 Oct 2003TL;DR: In this paper, the authors selectively blank a neurological channel of a medical device system (100) in the treatment of a nervous system disorder, in order to improve the performance of the system.
Abstract: Apparatuses and methods selectively blank a neurological channel of a medical device system (100) in the treatment of a nervous system disorder.
240 citations
27 Apr 1987
TL;DR: This paper establishes a connection between Shannon's theory of communication and information flow models, such as the Goguen-Meseguer model, that view a reference monitor as a state-transition automaton that takes the channel associated with a machine and a compromise policy as a measure of covert channel information rate.
Abstract: Techniques for detecting covert channels are based on information flow models This paper establishes a connection between Shannon's theory of communication and information flow models, such as the Goguen-Meseguer model, that view a reference monitor as a state-transition automaton The channel associated with a machine and a compromise policy is defined, and the capacity of that channel is taken as a measure of covert channel information rate
239 citations