Sharif Digital Repository

In this paper, we consider a different strategy for Broadcast-Relay- Networks (BRN) with two relays. There are a transmitter, two relays and two receivers in this network. The message of the transmitter intended to the receivers, has both common and private parts. The relays partially cooperate with each other and with the transmitter to send the common part of the message. The private parts of the message are sent to the corresponding receiver by the cooperation of the corresponding relay. We propose an achievable rate region for this network. In the proof, we take advantage of regular encoding/sliding window decoding at relays and simultaneous backward decoding analysis at receivers. The... 

In this paper we consider the real, discrete time asymmetric Gaussian parallel relay network, the more realistic model than the symmetric one considered by Schein-Gallagar. We present achievable rates for this network that are superior rates to the Schein-Gallagar rates. The proposed methods are based on the superimposition technique used for the degraded broadcast channel and also cooperation of the relays to send as much as possible information to the receiver at the multiple access side  

In this paper an approach for blind source separation in bilinear (or linear quadratic) mixtures is presented. The proposed algorithm employs the same recurrent structure as [Hosseini and Deville, 2003) for separating these mixtures . However, instead of maximal likelihood, our algorithm is based on minimizing the mutual information of the outputs for recovering the independent components. Simulation results show the efficiency of the proposed algorithm. © 2009 IEEE  

In this paper, we propose an information-theoretic constructive scheme based on generalized block Markov encoding strategy for obtaining an achievable rate for multirelay networks. The coding scheme is based on partial decoding scheme where the relay decodes only part of the transmitted message. The proposed achievable rate is then used to establish the capacity of a class of semi-deterministic relay networks composed of semi-deterministic relay channels. It is shown that the proposed rate will include those of previously proposed rates based on decode-and-forward strategy in some special cases. ©2007 IEEE  

Analytical models exist for evaluating gossip-based information propagation. Up to now these models were developed only for fully connected networks. We provide analytical models for information propagation of a push-pull gossiping protocol in a wireless mesh network. The underlying topology is abstracted away by assuming that the wireless nodes are uniformly deployed. We compare our models with simulation results for different topologies  

One of non-cooperative illuminators recently considered for passive radar applications is the DVB-T (Digital Video Broadcasting - Terrestrial) station. The thumbtack ambiguity function of the DVB-T signal in addition to being stationary makes such signal a good candidate for such applications. However, certain ambiguities in its ambiguity function necessitates certain issues to be carefully considered when DVB-T signals are to be utilized. In this paper, after studying the origins of these ambiguities, we propose special processing schemes to resolve them  

One of the attractive opportunistic signals for passive radar applications is the DVB-T (Digital Video Broadcasting- Terrestrial) signal. The thumbtack ambiguity function of the DVB-T signal in addition to being stationary makes such signal a good candidate for such applications. In this paper we want to consider its feasibility for this application in more details. So we first examin this signal for the main parts of the the passive radar: Resolving ambiguities before evaluating CAF and direct path intereference rejection, and then consider its processing gain in detecting targets  

Chip multiprocessors (CMPs) issue write invalidations (WIs) to assure program correctness. In conventional snoop-based protocols, writers broadcast invalidations to all nodes as soon as possible. In this work we show that this approach, while protecting correctness, is inefficient due to two reasons. First, many of the invalidated blocks are not accessed after invalidation making the invalidation unnecessary. Second, among the invalidated blocks many are not accessed anytime soon, making immediate invalidation unnecessary. While invalidating the first group could be avoided altogether, the second group's invalidation could be delayed without any performance or correctness cost. Accordingly,... 

In this paper, an algorithm for ECG denoising and compression based on a sparse separable 2-dimensional transform for both complete and overcomplete dictionaries is studied. For overcomplete dictionary we have used the combination of two complete dictionaries. The experimental results obtained by the algorithm for both complete and overcomplete transforms are compared to soft thresholding (for denoising) and wavelet db9/7 (for compression). It is experimentally shown that the algorithm outperforms soft thresholding for about 4dB or more and also outperforms Extended Kalman Smoother filtering for about 2dB in higher input SNRs. The idea of the algorithm is also studied for ECG compression,... 

As semantic web grows, security concerns increase. One concern is controlling accesses to resources in this environment. In order to infer whether the access is allowed or not, different information of different entities including contextual information should be involved. From access control point of view, we divide the entities in semantic web into three categories: resources (objects), requesters (subjects), and environment (infrastructure, time, and location). In this paper, we present a semantic-based context-aware access control framework to be applied in semantic web, considered as a multi-domain environment. To handle context information in the framework, we propose a context... 

We introduce a new communication model consisting of two interfering broadcast channels with one cognitive transmitter, who knows the message transmitted by the other non-cognitive transmitter, in a non-causal manner. An achievable rate region is derived for this model. The region is computed based on the Marton region for the general broadcast channel and its extension by Steinberg to the broadcast channel with the states known at the transmitter. By using the region evaluated, an achievable rate for the Gaussian broadcast channel is derived. © 2008 IEEE  

Agile Software Development is regarded as an effective and efficient approach, mainly due to its ability to accommodate rapidly changing requirements, and to cope with modern software development challenges. There is therefore a strong tendency to use agile software development methodologies where applicable; however, the sheer number of existing agile methodologies and their variants hinders the selection of an appropriate agile methodology or method chunk. Methodology evaluation tools address this problem through providing detailed evaluations, yet no comprehensive evaluation framework is available for agile methodologies. We introduce the Comprehensive Evaluation Framework for Agile... 

In this paper, we propose a new concept of relaying named parallel relaying to obtain a new achievable rate for relay networks. The proposed encoding scheme is based on partial decoding, where the relay decodes only part of the transmitted message. The superiority of our proposed method to the previous ones is that, it can be applied to the relay networks with general structure, not necessarily with feed-forward structure. The proposed achievable rate is also used to establish the capacity of a class of semi-deterministic relay network which is a generalization of Aref network. © 2008 IEEE  

In this paper, we introduce a generalization of the Multiple-Access-Relay- Channel (MARC) called Multiple-Access-Relay-Network (MARN). In the proposed network, there are many transmitters, many relays and one receiver. The MARC model was first introduced by Kramer and consists of many transmitters, one receiver and only one relay.We also define semi-deterministic MARN, in which the output of the link between each transmitter and each relay is a deterministic function of the transmitter's input. We first obtain an achievable rate region for MARN by considering Partial Decode-and-Forward (PDF) strategy at the relays. Then we show that in semi-deterministic MARN, the proposed achievable rate... 

We define partial cognitive relay channel as a twotransmitter, two-receiver interference channel with a relay node such that one of the transmitters is a cognitive transmitter. As a more feasible assumption we assume that the cognitive transmitter has non-causally access to a part of the other transmitter's encoded message. The cognitive radio transmitter transmits simultaneously over the same channel instead of waiting for an idle channel which is traditional for a cognitive radio. We calculate the achievable rate region for partial cognitive relay channel based on the combination of partial decode-compress and forward for the relay, rate-splitting and Gel'fand and Pinsker coding. Numerical... 

Agile Software Development is regarded as an effective and efficient approach, mainly due to its ability to accommodate rapidly changing requirements, and to cope with modern software development challenges. There is therefore a strong tendency to use agile software development methodologies where applicable; however, the sheer number of existing agile methodologies and their variants hinders the selection of an appropriate agile methodology or method chunk. Methodology evaluation tools address this problem through providing detailed evaluations, yet no comprehensive evaluation framework is available for agile methodologies. We introduce the Comprehensive Evaluation Framework for Agile... 

Recently, great attention was intended toward overcomplete dictionaries and the sparse representations they can provide. In a wide variety of signal processing problems, sparsity serves a crucial property leading to high performance. Decomposition of a given signal over two or more dictionaries with sparse coefficients is investigated in this paper. This kind of decomposition is useful in many applications such as inpainting, denoising, demosaicing, speech source separation, high-quality zooming and so on. This paper addresses a novel technique of such a decomposition and investigates this idea through inpainting of images which is the process of reconstructing lost or deteriorated parts of... 

Magnetic Nanoparticle Hyperthermia is a new auxiliary technique for cancer treatment, in which the temperature of tumor cells is elevated and maintained to a therapeutic level. Up to now a few researches have been done for Microwave Magnetic Hyperthermia. The authors have studied behavior of MNPs in Microwave field for hyperthermia application. The frequency and power of produced field was 915MHz and 25 Watts. © 2009 Springer-Verlag  

Nowadays, wireless sensor networks are known as a new challenge in network science. New features of these networks have made it impossible to use the traditional routing protocols. The most important challenge of these networks is the limited energy of nodes. In this paper, we will introduce MEHR as a multi-hop location-unaware hierarchical routing protocol to decrease the energy consumption in nodes, and to increase the network lifetime, we also apply MEHR to reach to a scalable routing. We will introduce a new factor to select candidate nodes and to send intra-cluster messages. We will use place-advertisement messages of sink, and a limiting parameter and also overhearing concept to create... 

In this paper, we present a new generalization of the well-known Compress-and-Forward strategy for relay networks. We propose an offset decoding at destination, where destination considers an ordered partition of relays and decodes information of any partition with the help of information from prior partitions. We show that when we do not partition the set of relays, our result improves the result of Kramer, et al. A geometrical method is utilized to unify results of different ordered partitioning. Also, the unified result has a celebrated source-channel coding separation interpretation. © 2008 IEEE