Wireless sensor networks: performance analysis in indoor scenarios

We evaluate the performance of realistic wireless sensor networks in indoor scenarios. Most of the considered networks are formed by nodes using the Zigbee communication protocol. For comparison, we also analyze networks based on the proprietary standard Z-Wave. Two main groups of network scenarios are proposed: (i) scenarios with direct transmissions between the remote nodes and the network coordinator, and (ii) scenarios with routers, which relay the packets between the remote nodes and the coordinator. The sensor networks of interest are evaluated considering different performance metrics. In particular, we show how the received signal strength indication (RSSI) behaves in the considered scenarios. Then, the network behavior is characterized in terms of end-to-end delay and throughput. In order to confirm the experiments, analytical and simulation results are also derived

Analytical framework for Adaptive Compressive Sensing for Target Detection within Wireless Visual Sensor Networks

Wireless visual sensor networks (WVSNs) are composed of a large number of visual sensor nodes covering a specifc geographical region. This paper addresses the target detection problem within WVSNs where visual sensor nodes are left unattended for long-term deployment. As battery energy is a critical issue it is always challenging to maximize the network's lifetime. In order to reduce energy consumption, nodes undergo cycles of active-sleep periods that save their battery energy by switching sensor nodes ON and OFF, according to predefined duty cycles. Moreover, adaptive compressive sensing is expected to dynamically reduce the size of transmitted data through the wireless channel, saving communication bandwidth and consequently saving energy. This paper derives for the first time an analytical framework for selecting node's duty cycles and dynamically choosing the appropriate compression rates for the captured images and videos based on their sparsity nature. This reduces energy waste by reaching the maximum compression rate for each dataset without compromising the probability of detection. Experiments were conducted on different standard datasets resembling different scenes; indoor and outdoor, for single and multiple targets detection. Moreover, datasets were chosen with different sparsity levels to investigate the effect of sparsity on the compression rates. Results showed that by selecting duty cycles and dynamically choosing the appropriate compression rates, the desired performanc

Hybrid Zigbee-RFID Networks for Energy Saving and Lifetime Maximization

"Proc. of the 3rd International Workshop on Distributed Cooperative Laboratories" ("Instrumenting the Grid", INGRID 2008), Lacco Ameno, Island of Ischia, Italy, April 2008

Performance analysis of Zigbee wireless sensor networks with relaying

In wireless sensor networks, transmitting information from sensors to a far Access Point (AP), out of direct transmission range, might make the use of relaying crucial. The goal of this paper is to study the impact of relaying in Zigbee wireless sensor networks. In particular, we focus on Zigbee wireless sensor networks and analyze scenarios where the sensors transmit to an AP (or coordinator) (i) directly, (ii) through a relay node (or router), or (iii) through two relays. We study how the network performance (in terms of delay, transmission rate, and throughput) is influenced by the number of sensors, the traffic load, and the use of ACKnowledgment (ACK) messages. This performance analysis is carried out with simulations, analytical considerations, and experimental measurements. Our results show that the use of one or two relays, combined with the use of ACK messages (not efficiently managed by the upper layers of the network protocol stack), may cause a significant performance degradation. On the opposite, if ACK messages are not used, then the performance improves significantly. In addition, we also consider the impact of the network lifetime on the network transmission rate. 1

A multi-dimensional characterization of clustered Zigbee networks: performance trade-offs

In this paper, we characterize Zigbee networks composed by a set of source nodes which transmit to an access point (AP) either directly or through intermediate relay nodes. In the latter case, both uniform and non-uniform clustering configurations are considered. We evaluate the delay (between transmission and reception of data packets) as a function of the network transmission rate (relative to successful packet transmissions) and tolerable network death level (which will be properly defined). Our results show the existence of a characteristic multidimensional performance surface describing the behavior of a Zigbee network in terms of the three mentioned performance indicators. We heuristically derive a closed-form expression for the network performance surface, by interpolating it through the sum of bidimensional Gaussian surfaces

Clustered Zigbee networks with data fusion: characterization and performance analysis

In this paper, we analyze the performance of clustered Zigbee wireless sensor networks (WSNs) with data fusion. Performance indicators at both physical (probability of decision error) and network (network transmission rate, throughput, aggregate throughput, delay, and network lifetime) layers are considered. Data fusion is carried out at the access point (AP) and, in clustered configurations, also at the clusterheads, which act as intermediate fusion centers (FCs). The goal of this paper is to shed light on the joint impact of topology and data fusion on the network performance. The presented results, mainly obtained through Opnet-based simulations, show clearly that the operational point of a Zigbee WSN with data fusion lies over a characteristic multi-dimensional surface, whose shape remains the same regardless of the number of nodes in the network. The existence of this peculiar surface highlights fundamental performance trade-offs in Zigbee networks

Distributed Data Storage and Retrieval Schemes in RPL/IPv6-based networks

This chapter deals with distributed data storage and retrieval techniques in WSNs. The focus is on WSN systems for the Internet of Things (IoT), a new vision of the Internet aiming at pushing IP conne tivity into smart objects. The range of objects involved in the Internet of Things also encompasses Radio Frequency Identi ation (RFID) and Machine-to-Machine (M2M) systems, to cite a few. These technologies will be also described in detail