On the Energy Efficiency of LT Codes in Proactive Wireless Sensor Networks

This paper presents an in-depth analysis on the energy efficiency of Luby Transform (LT) codes with Frequency Shift Keying (FSK) modulation in a Wireless Sensor Network (WSN) over Rayleigh fading channels with pathloss. We describe a proactive system model according to a flexible duty-cycling mechanism utilized in practical sensor apparatus. The present analysis is based on realistic parameters including the effect of channel bandwidth used in the IEEE 802.15.4 standard, active mode duration and computation energy. A comprehensive analysis, supported by some simulation studies on the probability mass function of the LT code rate and coding gain, shows that among uncoded FSK and various classical channel coding schemes, the optimized LT coded FSK is the most energy-efficient scheme for distance d greater than the pre-determined threshold level d_T , where the optimization is performed over coding and modulation parameters. In addition, although the optimized uncoded FSK outperforms coded schemes for d < d_T , the energy gap between LT coded and uncoded FSK is negligible for d < d_T compared to the other coded schemes. These results come from the flexibility of the LT code to adjust its rate to suit instantaneous channel conditions, and suggest that LT codes are beneficial in practical low-power WSNs with dynamic position sensor nodes.Comment: accepted for publication in IEEE Transactions on Signal Processin

Recent advances in wireless sensor networks with environmental energy harvesting

Shu, L.; Liao, W.; Lloret, J.; Wang, L. (2016). Recent advances in wireless sensor networks with environmental energy harvesting. International Journal of Sensor Networks. 21(4):205-207. http://hdl.handle.net/10251/18736720520721

Airborne Wireless Sensor Networks for Airplane Monitoring System

In traditional airplane monitoring system (AMS), data sensed from strain, vibration, ultrasound of structures or temperature, and humidity in cabin environment are transmitted to central data repository via wires. However, drawbacks still exist in wired AMS such as expensive installation and maintenance, and complicated wired connections. In recent years, accumulating interest has been drawn to performing AMS via airborne wireless sensor network (AWSN) system with the advantages of flexibility, low cost, and easy deployment. In this review, we present an overview of AMS and AWSN and demonstrate the requirements of AWSN for AMS particularly. Furthermore, existing wireless hardware prototypes and network communication schemes of AWSN are investigated according to these requirements. This paper will improve the understanding of how the AWSN design under AMS acquires sensor data accurately and carries out network communication efficiently, providing insights into prognostics and health management (PHM) for AMS in future

Cross-layer network lifetime optimization considering transmit and signal processing power in WSNs

Maintaining high energy efficiency is essential for increasing the lifetime of wireless sensor networks (WSNs), where the battery of the sensor nodes cannot be routinely replaced. Nevertheless, the energy budget of the WSN strictly relies on the communication parameters, where the choice of both the transmit power as well as of the modulation and coding schemes (MCSs) plays a significant role in maximizing the network lifetime (NL). In this paper, we optimize the NL of WNSs by analysing the impact of the physical layer parameters as well as of the signal processing power (SPP) P_sp on the NL. We characterize the underlying trade-offs between the NL and bit error ratio (BER) performance for a predetermined set of target signal-to-interference-plus-noise ratio (SINR) values and for different MCSs using periodic transmit-time slot (TS) scheduling in interference-limited WSNs. For a per-link target BER requirement (PLBR) of 10^?3, our results demonstrate that a ’continuous-time’ NL in the range of 0.58?4.99 years is achieved depending on the MCSs, channel configurations, and SPP

Application framework for wireless sensor networks [thesis]

Wireless Sensor Networks (WSNs) are based on innovative technologies that had revolutionized the methods in which we interact with the environment; i.e., through sensing the physical (e.g., fire motion, contact) and chemical (e.g., molecular concentration) properties of the natural surroundings. The hardware in which utilized by WSNs is rapidly evolving into sophisticated platforms that seamlessly integrate with different vendors and protocols (plug-n-play). In this thesis, we propose a WSN framework which provides assistance with monitoring environmental conditions; we focus on three main applications which include: a. Air-quality monitoring, b. Gas-leak detection, and c. Fire sensing. The framework involves four specifications: 1. Over the air programming (OTAP), 2. Network interconnections, 3. Sensors manageability, and 4. Alarm signaling. Their aim is to enhance the internetwork relations between the WSNs and the outside-world (i.e., main users, clients, or audience); by creating a medium in which devices efficiently communicate, independent of location or infrastructure (e.g., Internet), in order to exchange data among networked-objects and their users. Therefore, we propose a WSN-over-IP architecture which provides several renowned services of the Internet; the major functionalities include: live-data streaming (real-time), e-mailing, cloud storage (external servers), and network technologies (e.g., LAN or WLAN). WSNs themselves operate independently of the Internet; i.e., their operation involve unique protocols and specific hardware requirements which are incompatible with common network platforms (e.g., within home network infrastructure). Hybrid technologies are those which support multiple data-communication protocols within a single device; their main capabilities involve seamless integration and interoperability of different hardware vendors. We propose an overall architecture based on hybrid communication technology in which data is transmitted using three types of protocols: 802.11 (Wi-Fi), 802.15.4 and Digimesh (WSN)

A wireless reference node to provide self-calibration capability to wireless sensors networks

Wireless sensors networks (WSNs) are constantly expanding their application field, from simple two-state measurements (e.g., on/off, proximity detection, etc.) to distributed many-parameter measurements. Commercial WSNs offer a wide range of functions and performance with sensors sometimes achieving accuracy comparable with desktop instrumentation. However, the advantage of using such sensors for in-situ monitoring is often offset by the need of partially dismantling the network at the time of periodic network nodes calibration. As a result, new reference standards suitable for automatic and in-situ calibration of such sensors networks are needed in order to reduce the calibration cost, the inherent inefficiency and the logistic problems of a laboratory calibration, further exploiting the communication capabilities of a WSN. This work discusses the development of a wireless reference node (WRN) for the measuring of environment quantity such as air temperature (T) and relative humidity (RH). The module was developed for accurate measurements of additional environmentrelated quantities whose principle is based on a capacitive sensing mechanism (e.g. pressure, air-flow, moisture, etc…). The WRN performance was investigated in the temperature range from 0 °C to 40 °C and in the relative humidity range from 10 %rh to about 90 %rh for its potential use as a transfer standard for automatic in-situ calibrations. Some of novelties here reported were patented and are now available to upgrade a basic WSN with an automatic in-situ calibration capability