Sharif Digital Repository

In this paper we evaluate the performance of Energy Management and Building Automation Systems in smart environment using wireless sensor network. We describe some aspects of smart grid and then explain the related communication models of smart meters and building management or energy management systems in a smart home. We propose three models, then we compare these models and we select a model for our test bed. We implement the selected model in real environment using wireless sensor network. We analyse network delay to find out whether wireless sensor network is useful or not. With proposed model, we can save up to 57% in energy cost. Also, we develop In- home display to inform customers... 

The problem of extracting low-dimensional structure from high-dimensional data arises in many applications such as machine learning, statistical pattern recognition, wireless sensor networks, and data compression. If the data is restricted to a lower dimensional subspace, then simple algorithms using linear projections can find the subspace and consequently estimate its dimensionality. However, if the data lies on a low-dimensional but nonlinear space (e.g., manifolds), then its structure may be highly nonlinear and, hence, linear methods are doomed to fail. In this paper, we introduce a new technique for dimensionality reduction based on point-wise operators. More precisely, let $ {bf A} n... 

In this paper, after reviewing the basic structure for implementing WSN in smart grid, we would give a case study for implementation of such a structure in a smart home. It will be shown that using new generation cellular network structure, gives a basic improvement the infrastructure needed for gathering the information and taking a real time monitoring and control of a simplified model of a smart grid executed as a smart home. We will take the advantage of computer simulations to show the reliability of this method and finally, we will analyze the advantages of using this proposed structure in a smart grid. [1, 4]  

One of the most concerning problems in Smart Grids is the lack of a proper data acquisition system with high security, desired flexibility and required network capacity. These demands prove the vital role of communications in conjunction with smart girds. In this paper, Wireless Sensor Networks are proposed as a compatible choice for satisfying these requirements. However, Wireless Sensor Networks utilized for smart grids necessitate some specifications. We will study these specifications and suggest viable manipulations in the architecture of sensor nodes and network topology. Furthermore, after analyzing the properties of various communication systems, an appropriate choice is included in... 

Wireless sensor networks (WSNs) are composed of hundreds or thousands of small nodes, which work together and associate with a specific task or tasks to do. It is expected that wireless sensor networks will be used widely in many applications in the near future. One of the most important issues in WSNs is localisation. There are crucial problems over network localisation such as security attacks (internal or external), energy efficiency, and accuracy, which impact performance and energy-consuming of wireless sensor networks. The main source of these problems is network topology. A long-thin network topology (LTNT) in wireless sensor can produce errors in network localisation due to special... 

Two important objectives in wireless sensor networks are reliability and reducing energy consumption. Hence, overcoming energy constraints and utilizing error control schemes such as Automatic Repeat Request (ARQ) and Forward Error Correction (FEC) are necessary to improve the energy efficiency and reliability. However, these two concerns are at odds, so there is a trade-off between them. Considering this point, the impact of various error control schemes on these objectives and the trade-off between them has been considered in Bluetooth networks recently. However, all these works consider ideal assumptions (e.g., perfect error detection) only. This work evaluates the energy-efficiency of... 

Wireless Sensor Networks (WSNs) are prone to faults due to battery depletion of nodes. A node failure can disturb routing as it plays a key role in transferring sensed data to the end users. This paper presents a Fault-Tolerant and Energy-Aware Mechanism (FTEAM), which prolongs the lifetime of WSNs. This mechanism can be applied to cluster-based WSN protocols. The main idea behind the FTEAM is to identify overlapped nodes and configure the most powerful ones to the sleep mode to save their energy for the purpose of replacing a failed Cluster Head (CH) with them. FTEAM not only provides fault tolerant sensor nodes, but also tackles the problem of emerging dead area in the network. Our... 

Energy constraint is the most critical problem in wireless sensor networks (WSNs). To address this issue, clustering has been introduced as an efficient way for routing. However, the available clustering algorithms do not efficiently consider the geographical information of nodes in cluster-head election. This leads to uneven distribution of cluster-heads and unbalanced cluster sizes that brings about uneven energy dissipation in clusters. In this paper, an Efficient Distributed Cluster-head Election technique for Load balancing (EDCEL) is proposed. The main criterion of the algorithm, dispersal of cluster-heads, is achieved by increasing the Euclidian distance between cluster-heads.... 

Wireless sensor networking remains one of the most exciting and challenging research domains of our time. Sensor nodes are arranged in the clusters and relay nodes could have been used as cluster head with more power, but this method has a Low Speed for networks with many sensors. In another method Storage and forwarding nodes are used to transfer the data from sensors to the base station. In this method, the data might have been failed due to the damage of the storage node. In this article, a hybrid method has been used to improve the network quality, which in that network, in addition to the forwarding and storage nodes, there is also cluster head. The purpose of this article is to solve... 

Wireless sensor networks are tiny devices with limited computation and energy capacities. For such devices, data transmission is a very energy-consuming operation. It thus becomes essential to increase the lifetime of a WSN by minimizing the number of bits sent by each device. One well known approach is to aggregate sensor data. Data aggregation is used to eliminate redundancy and minimize the number of transmissions in order to save energy. Most energy efficient aggregation protocols have focused on cluster-based structure approaches. In this paper, we investigate the efficiency of data aggregation by focusing on two aspects of the problem: first how to improve cluster-based routing... 

Error control is an important mechanism for providing robust multimedia communication in wireless sensor networks. Although there have been several research works in analysis of error control mechanisms in wireless multimedia networks and wireless sensor networks, but none of them are directly applicable to the wireless multimedia sensor networks (WMSNs) which has resource and performance constraints of WSNs as well as QoS requirements of multimedia communications. In this paper, we comprehensively evaluate the performance of several error control mechanisms in WMSNs. The results of our analysis provide an extensive comparison between automatic repeat request (ARQ), forward error correction... 

Power and bandwidth constraints are two major challenges in wireless sensor networks. Since a considerable amount of energy in sensor networks is consumed for data transmission, compression techniques may prolong the life of such networks. Moreover, with fewer bits to transmit, the network can cope better with the problem of inadequate bandwidth. In this paper, we consider an image sensor network and propose a paradigm based on the principles of Distributed Source Coding (DSC) for efficient compression. Our method relies on high correlation between the sensor nodes. The algorithm consists of two phases: the Training Phase and the Main Phase. In the Training Phase an aggregation node or a... 

Multimedia multicast with two servers based on the mul- titerminal source coding is studied in some previous researches. Due to the possibility of providing an approach for practical code design for more than two correlated sources in IMTSC/CEO setup, in this paper, the framework of Slepian-Wolf coded quantization is extended and a practical code design is presented for IMTSC/CEO with the number of encoders greater than two. Then the multicast system based on the IMTSC/CEO is applied to the cases with three, four and five servers. Since the underlying code design approach for the IMTSC/CEO problem has the capability of applying to an arbitrary number of active encoders, the proposed MMBMSC... 

The aim of this paper is introducing coding scheme that can potentially achieve the sum rate-distortion bound of Gaussian IMTSC/CEO problem with arbitrary number of encoders. No previous work has been reported on code design for the IMTSC/CEO problem with the number of encoders greater than two. In this paper the framework of Slepian-Wolf coded quantization is extended to the case with the number of encoders greater than two. On the other hand, we apply the approach to the case of unequal levels of the observation noise at the encoders. Encoding process consists of trellis coded quantization (TCQ) and LDPC codes. The proposed framework can be easily used for any number of active encoders... 

The reliability of wireless sensor networks (WSNs) depends on both sensing coverage and reliable transmission of collected data provided by the target cluster of sensors in the proximity of the phenomenon to the observer. In this paper, we establish a probabilistic fundamental quantitative notion for performance-critical applications on reliable information transfer and propose a new analytical model to calculate the coverage-oriented reliability of cluster-based WSNs. Here, the packet loss probability is modeled as a function of two main parameters. The first is the probability of link failure when the node's buffer at the end point of the link is full (discarding the packet) or when the... 

This letter proposes a sparse diffusion algorithm for 1-bit compressed sensing (CS) in wireless sensor networks, and the algorithm is inherently robust against impulsive noise. The approach exploits the diffusion strategy from distributed learning in the 1-bit CS framework. To estimate a common sparse vector cooperatively from only the sign of measurements, a steepest descent method that minimizes the suitable global and local convex cost functions is used. A diffusion strategy is suggested for distributive learning of the sparse vector. A new application of the proposed algorithm to sparse channel estimation is also introduced. The proposed sparse diffusion algorithm is compared with both... 

Wireless Sensor Network (WSN) should be capable of fulfilling its mission, in a timely manner and without loss of important information. In this paper, we propose a new analytical model for calculating RRT (Reliable Real-Time) degree in multihop WSNs, where RRT degree describes the percentage of real-time data that the network can reliably deliver on time from any source to its destination. Also, packet loss probability is modeled as a function of the probability of link failure when the buffer is full and the probability of node failure when node's energy is depleted. Most of the network properties are considered as random variables and a queuing theory based model is derived. In this... 

In this paper, we study the downlink of cooperative Direct-Sequence Code Division Multiple Access (DS-CDMA), where a set of Mobile Terminals (MT) are cooperating with the purpose of improving their downlink communications reliability with the Base Station (BS). In order to achieve the spatial diversity, a new cooperation scenario is proposed. Afterward, in addition to multiuser precoding, Maximum Ratio Combining (MRC) according to the Maximum Signal to Noise Ratio (MSNR) criterion at the destination is investigated. Then, the optimal transmission power control strategy under a fixed total power constraint is illustrated and analyzed. Compared with equal transmission power assignment where BS...