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Index codes reduce the number of bits broadcast by a wireless transmitter to a number of receivers with different demands and with side information. It is known that the problem of finding optimal linear index codes is NP-hard. We investigate the performance of different heuristics based on rank minimization and matrix completion methods for constructing linear index codes over the reals. As a summary...
The question of under what condition some side information for index coding can be removed without affecting the capacity region is studied, which was originally posed by Tahmasbi, Shahrasbi, and Gohari. To answer this question, the notion of unicycle for the side information graph is introduced and it is shown that any edge that belongs to a unicycle is critical, namely, it cannot be removed without...
Blocks-based programming environments offer an alternative program representation to textual source code that simplifies the considerations of syntax for novices. This position paper raises the question of whether additional affordances related to transparency of data, transparency of semantics, and liveness of execution can be consistently added to these environments to obtain some significant advantages...
We derive an exponentially decaying upper-bound on the unnormalized amount of information leaked to the wire-tapper in Wyner's wire-tap channel setting. We characterize the exponent of the bound as a function of the randomness used by the encoder. This exponent matches that of the recent work of Hayashi [12] which is, to the best of our knowledge, the best exponent that exists in the literature. Our...
In network coding theory, when wiretapping attacks occur, secure network coding is introduced to prevent information from being leaked to adversaries. In practical network communications, secure constraints vary with time. How to effectively deal with information transmission and information security simultaneously under different security-levels is introduced in this paper as variable-security-level...
For implementation of a fast arithmetic algorithm and efficient hardware realization, signed digit representation is crucial. Redundant binary (RB) and 2's complement number representation is the most widely used technique for representation signed digit number. The drawbacks of RB technique include multi valued logic as well as need of unconventional hardware blocks. Though 2's complement notation...
Alice aims at transmitting Bob a message to be kept secret from Eve, with the assistance of relays operating in a decode-and-forward fashion. Each link between node couples comprises a set of parallel channels. Both Alice and relays knows all legitimate channel gains, while they only have a statistical knowledge of the channels to Eve. By fixing a secrecy outage probability per channel, we optimize...
A method for constructing LDPC codes is presented based on a (14, 8) extended Hamming code which is formed via column splitting of the (7, 4) Hamming code. With this code and hybrid construction, it is effortless to generate an LDPC code by mapping the (14, 8) extended Hamming code to components of the parity-check matrix of the LDPC code. Simulation results show that the capacity of hybrid construction...
We analyze the impact of user cooperation in the two-way relay channel (TWRC) by letting each user send a quantized version of its received signal in addition to its own message. The proposed scheme is based on quantize-forward (QF) and partial decode-forward (PDF) relaying with sliding window decoding at the relay, and QF relaying with backward decodings at each user. For Gaussian channels, examples...
In this paper, we propose a new rateless code based on overlapped generations. This proposed scheme works very well especially in a broadcast scenario, where channels with different characteristics are involved in the system. In the proposed scheme, we allow the adjacent generations to overlap. Our main focus is on the design of rateless codes to make any receiver able to recover all the source file...
Tunstall proposed an efficient algorithm for constructing the optimal dictionary of any particular size to obtain a variable-to-fixed code. More accurately, the algorithm constructs the optimal uniquely parsable dictionary. In fact, Savari showed that, if one allows herself to consider plurally parsable dictionaries, better codes may be constructed. Savari found a class of plurally parsable dictionaries...
In this paper a new compression scheme has been formulated based on jointly delta modulation with biasing and Run Length Encoding technique for Direct Normalized Solar Irradiance data. The key features of this Compression Algorithm (Delta Modulation with Biasing and Run Length Encoding techniques viz. DMBRLE) are: it requires less memory as it belongs to direct compression method and its lossless...
Recently sparse coding have been highly successful in image classification mainly due to its capability of incorporating the sparsity of image representation. In this paper, we propose an improved sparse coding model based on linear spatial pyramid matching(SPM) and Scale Invariant Feature Transform (SIFT) descriptors. The novelty is the simultaneous non-convex and non-negative characters added to...
We consider a 2-user Gaussian Multiple-Access Wiretap channel (GMAC-WT), with the Eavesdropper (E) having access to signal from only one (say, T2) of the two transmitters. We characterize the capacity region of this channel approximately within. 5 bits, where the approximation is in terms of only T1's rate or the sum-rate depending on the relative strength of the eavesdropper's channel. However, the...
Wireless sensor networks (WSN) provide attractive solutions for data exchange in a variety of applications from military surveillance to medical and environmental monitoring. The commonality in all such applications is that the data collected in some nodes of the network is needed at some other nodes, for instance in a data collector node. The nodes are typically limited in terms of power, memory,...
The proliferation of Web-based learning objects makes finding and evaluating online resources problematic. While established Learning Analytics methods use Web interaction to evaluate learner engagement, there is uncertainty regarding the appropriateness of these measures. In this paper we propose a method for evaluating pedagogical activity in Web-based comments using a pedagogical framework, and...
In this paper the approach is to embed coding techniques into neural networks in order to increase their performance as associative memories in the presence of partial erasures. The motivation comes from the recent works by Gripon and Berrou, which benefit from error correcting codes in neural networks schemes like Hopfield neural networks. The construction introduced stores messages as cliques of...
Consider the following scenario: A data storage service provider provides an erasure code based distributed storage system (DSS). For the same data, the service provider gives several options: an (ni, ki) erasure code based DSS for i = 1,2, …, m. The service provider charges differently for different options (say dollar Pi for an (ni, ki) erasure code based DSS for the data B of size |B|). A client...
Suppose that a data storage service provider implements a functional MSR code based distributed storage system (DSS). Consider a scenario where the service provider has implemented an (n1; k1;B; d1; t1) functional MSR code based DSS, where B is the file that is stored. At a later point of time, due to certain considerations (such as storage cost, download bandwidth to repair failed nodes etc.), the...
The energy used to transmit a single bit of data between the devices in sensor networks is equal to the energy for performing hundreds of instructions in those devices. Thus the reduction of the data necessary to transmit, while keeping the same functionality of the employed algorithms is a formidable and challenging scientific task. We describe an algorithm called Small Set of Allowed Coefficients...
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