Context Modeling

Cognitive radio has the ability to sense the environment and adapt its behavior to optimize communication features, such as quality of service in the presence of interference and noise. In physical layer to achieve this goal, different phases of sensing, channel estimation, and configuration selection are necessary. The sensing part measures the interference level, recognize the spectrum holes, and send this information to channel estimator. In the next step, channel state information (CSI) is used for data detection and also sent to the transmitter through a limited feedback. CSI feedback consists of achievable rate, SNR value, modulation or coding schemes (MCS). Feedback link improves the system performance in the cost of complexity and delay. In this paper, we present and compare different feedback schemes for cognitive radio and study the channel capacity when an imperfect feedback link is corrupted by noise and delay.

Abstract— A computational parallel approach for 3D ray-tracing techniques in the radio propagation prediction is presented. This approach considers that the main tasks in a 3D ray-tracing technique can be evaluated in an independent and/or parallel way. The workload distribution ...

Binary image compression is desirable for a wide range of applications, such as digital libraries, map archives, fingerprint databases, facsimile, etc. In this paper, we present a new highly efficient algorithm for lossless binary image compression. The proposed algorithm introduces a new method, direct redundancy elimination, to efficiently exploit the two-dimensional redundancy of an image, as well as a novel

Abstract-We describe a sequential universal data compression procedure for binary tree sources that performs the “double mixture.” Using a context tree, this method weights in an ef-ficient recursive way the coding distributions corresponding to all bounded memory tree sources, and ...

The idea of ubiquitous learning is to create a network of devices, people and situation that allows learning experiences to play out. This idea is attractive but it is not easily implemented. The GlobalEdu is a ubiquitous learning architecture integrated in ISAM, a software architecture that manages a large-scale pervasive environment. This paper presents a context-aware model implemented in GlobalEdu. Especially, we present the context management educational service and its interface with a pedagogical agent. A scenario application will be present too

For pragmatic information fusion system design and analysis, the user (commander or operator/analyst) needs information in a timely manner to conduct actionable intelligence. With the development of complex information fusion systems, the user still provides valuable inputs to the information fusion system in contextual reasoning and situation understanding. In this paper, we describe the Cognitive Observe-Orient-Decide-Act (C-OODA) model as a method of user and team analysis in the context of the Data Fusion Information Group (DFIG) Information Fusion Model. From the DFIG model [as an update to the Joint Directors of the Lab (JDL) model], we look at Level 5 Fusion of “user refinement” in the context of timely decision making. Using control theory, we present an example of user timeliness assessment in an information fusion decision making model analysis. We model the information input delays in reaching a decision and the action output delays in executing the decision. The C-OODA c...