A Communication Monitor for Wireless Sensor Networks Based on Software Defined Radio

Link quality estimation of reliability-crucial wireless sensor networks (WSNs) is often limited by the observability and testability of single-chip radio transceivers. The estimation is often based on collection of packer-level statistics, including packet reception rate, or vendor-specific registers, such as CC2420's Received Signal Strength Indicator (RSSI) and Link Quality Indicator (LQI). The speed or accuracy of such metrics limits the performance of reliability mechanisms built in wireless sensor networks. To improve link quality estimation in WSNs, we designed a powerful wireless communication monitor based on Software Defined Radio (SDR). We studied the relations between three implemented link quality metrics and packet reception rate under different channel conditions. Based on a comparison of the metrics' relative advantages, we proposed using a combination of them for fast and accurate estimation of a sensor network link

A Channel-Aware Adaptive Modem for Underwater Acoustic Communications

Acoustic underwater channels are very challenging, because of limited bandwidth, long propagation delays, extended multipath, severe attenuation, rapid time variation and large Doppler shifts. A plethora of underwater communication techniques have been developed for dealing with such a complexity, mostly tailoring specific applications scenarios which can not be considered as one-size-fits-all solutions. Indeed, the design of environment-specific solutions is especially critical for modulations with high spectral efficiency, which are very sensitive to channel characteristics. In this paper, we design and implement a software-defined modem able to dynamically estimate the acoustic channel conditions, tune the parameters of a OFDM modulator as a function of the environment, or switch to a more robust JANUS/FSK modulator in case of harsh propagation conditions. The temporal variability of the channel behavior is summarized in terms of maximum delay spread and Doppler spread. We present a very efficient solution for deriving these parameters and discuss the limit conditions under which the OFDM modulator can work. In such scenarios, we also calibrate the prefix length and the number of sub-carriers for limiting the inter-symbol interference and signal distortions due to the Doppler effect. We validate our estimation and adaptation techniques by using both a custom-made simulator for time-varying underwater channels and the well-known Watermark simulator, as well as real in field experiments. Our results show that, for many practical cases, a dynamic adjustment of the prefix length and number of sub-carriers may enable the utilization of OFDM modulations in underwater communications, while in harsher environments JANUS can be used as a fall-back modulation

A channel aware adaptive modem for underwater acoustic communications

Acoustic underwater channels are very challenging, because of limited bandwidth, long propagation delays, extended multipath, severe attenuation, rapid time variation and large Doppler shifts. A plethora of underwater communication techniques have been developed for dealing with such a complexity, mostly tailoring specific applications scenarios which can not be considered as one-size-fits-all solutions. Indeed, the design of environment-specific solutions is especially critical for modulations with high spectral efficiency, which are very sensitive to channel characteristics. In this paper, we design and implement a software-defined modem able to dynamically estimate the acoustic channel conditions, tune the parameters of a OFDM modulator as a function of the environment, or switch to a more robust JANUS/FSK modulator in case of harsh propagation conditions. The temporal variability of the channel behavior is summarized in terms of maximum delay spread and Doppler spread. We present a very efficient solution for deriving these parameters and discuss the limit conditions under which the OFDM modulator can work. In such scenarios, we also calibrate the prefix length and the number of sub-carriers for limiting the inter-symbol interference and signal distortions due to the Doppler effect. We validate our estimation and adaptation techniques by using both a custom-made simulator for time-varying underwater channels and the well-known Watermark simulator, as well as real in field experiments. Our results show that, for many practical cases, a dynamic adjustment of the prefix length and number of sub-carriers may enable the utilization of OFDM modulations in underwater communications, while in harsher environments JANUS can be used as a fall-back modulation

Interference diagnosis in wireless systems by using NI USRP

In both industrial and domestic environments, there will be a large increase of wireless communication systems. The density of wireless devices and need of additional bandwidth is expanding which is increasing the wireless interference. Interference emerges from unintended radiators is the main cause of degrading the Electromagnetic Compatibility and wireless communication performance in near field region and far field region and decrease the robustness and reliability. This paper presents methods of detection and removal of interference to improve EMC performance and wireless communication. We used NI USRP equipment for the diagnosis and provided the solutions to remove interference. The presented methods of interference diagnosis can efficiently optimize the performance of any wireless network

Proceedings of the Second International Mobile Satellite Conference (IMSC 1990)

Presented here are the proceedings of the Second International Mobile Satellite Conference (IMSC), held June 17-20, 1990 in Ottawa, Canada. Topics covered include future mobile satellite communications concepts, aeronautical applications, modulation and coding, propagation and experimental systems, mobile terminal equipment, network architecture and control, regulatory and policy considerations, vehicle antennas, and speech compression

State-of-the-art in Power Line Communications: from the Applications to the Medium

In recent decades, power line communication has attracted considerable attention from the research community and industry, as well as from regulatory and standardization bodies. In this article we provide an overview of both narrowband and broadband systems, covering potential applications, regulatory and standardization efforts and recent research advancements in channel characterization, physical layer performance, medium access and higher layer specifications and evaluations. We also identify areas of current and further study that will enable the continued success of power line communication technology.Comment: 19 pages, 12 figures. Accepted for publication, IEEE Journal on Selected Areas in Communications. Special Issue on Power Line Communications and its Integration with the Networking Ecosystem. 201

Power communications over the last kilometre

This thesis examines traditional methods of transmitting and receiving information over the last kilometre into homes and light industrial premises. As a direct result of the deregulation of electricity with the Electrical Deregulation Act of July 1989 [1] and the proliferation of large scale integration electronic devices such as microprocessors the need to transmit more data to and from such premises became urgent. The last kilometre problem of getting information to and from the customer’s premises to the node or data concentrator for connection to the available services, such as the internet, applies to any supplier from those that need to transfer large amounts of date such as on demand high definition television to those wishing to read utility meters remotely. Two competing techniques for transmitting small amounts of data at low data rates over the last kilometre between domestic and light commercial sites to the utility substation are investigated in this thesis. These techniques are narrow band VHF radio and low frequency power line carrier. A literature survey investigates the traditional methods of delivery information and the use of home networks and the latest research in power line carrier and broadband power line. The basis of radio propagation is presented including Maxwell’s equations. Two sets of trials are presented; the first set investigates a low frequency power line technology broadcast alarm system designed to inform residents living in higher risks areas around industrial sites such as oil refineries and chemical factories of important information and any alarm condition. The second set of trials, the radio trial, at 184 MHz, involved reading 2,500 domestic and light industrial electricity meters every 30 minutes during two week long periods. ConclusionBoth the radio meter reading system and low data rate power systems are viable in getting low data rate information to and from domestic and commercial properties. Both systems may be retrofitted quickly and cheaply depending on the data rates and amount of data to be transmitted. The radio meter system benefited from careful site surveys including monitoring of potential radio interference; the power line carrier system also benefited from site surveys and monitoring of line disturbance and line impedance