Cooperative communication in near field magnetic induction communication systems

University of Technology, Sydney. Faculty of Engineering and Information Technology.Near-Field Magnetic Induction Communication (NFMIC) is a relatively new technology which has been proposed for short-range applications such as body-area networks. Since it uses a rapidly-decaying magnetic near-field instead of an electromagnetic wave as the signal transmission mechanism, it is ideal for situations in which limited transmission range is actually an advantage, such as where minimising internetwork interference or avoiding location disclosure are considered important. To date, little work has been done on multihop techniques specifically designed for NFMIC systems. Most existing applications, such as Radio Frequency Identification (RFID) and Near Field Communication (NFC) are strictly point-to-point. However, when each network node only needs to transmit occasionally, multihop relaying techniques have the potential to significantly reduce power consumption and overall levels of magnetic field egress. Cooperative retransmission strategies, where network nodes that are neither a transmission source nor sink can participate in relaying of frames at the physical layer, have been proposed as a solution for range-extension of conventional electromagnetic/radiofrequency networks. This thesis aims to propose, analyse and simulate a variety of strategies for cooperative relaying which are appropriate for the specific needs of multihop NFMIC networks. A link budget model for NFMIC is firstly developed and thoroughly analysed, for a variety of non-ideal channel conditions. Three relaying strategies are then proposed and evaluated using the link-budget model under a variety of channel conditions, varying from near-ideal to the pathological case, and a wide variety of source, destination and relay node placement configurations. Simulation results are used to identify the key factors which govern the performance of each technique and the conditions under which throughput can be maximised. A new link metric, which accurately captures these factors, is proposed and its benefits demonstrated through simulation. Finally, a number of opportunities for future study are identified

Multihop relay techniques for communication range extension in near-field magnetic induction communication systems

In this paper, multihop relaying in RF-based com munications and near field magnetic induction communication (NFMIC) is discussed. Three multihop relay strategies for NFMIC are proposed: Non Line of Sight Magnetic Induction Relay (NLoS-MI Relay), Non Line of Sight Master/Assistant Magnetic Induction Relay1 (NLoS-MAMI Relay1) and Non Line of Sight Master/Assistant Magnetic Induction Relay2 (NLoSMAMI Relay2). In the first approach only one node contributes to the communication, while in the other two techniques (which are based on a master-assistant strategy), two relaying nodes are employed. This paper shows that these three techniques can be used to overcome the problem of dead spots within a body area network and extend the communication range without increasing the transmission power and the antenna size or decreasing receiver sensitivity. The impact of the separation distance between the nodes on the achievable RSS and channel data rate is evaluated for the three techniques. It is demonstrated that the technique which is most effective depends on the specific network topology. Optimum selection of nodes as relay master and assistant based on the location of the nodes is discussed. The paper also studies the impact of the quality factor on achievable data rate. It is shown that to obtain the highest data rate, the optimum quality factor needs to be determined for each proposed cooperative communication method. © 2013 ACADEMY PUBLISHER

Low Power Wake-up Signaling for Dense Sensor Networks

In wireless sensor networks, nodes are required to reduce their idle listening time in order to minimize energy consumption and increase their lifetime. The idle listening time is decreased by making the nodes remain in sleep mode and wake up only when they are required to sense or transmit information about an event. This strategy requires the source node to send a wake-up signal before it transmits data to the network. This wake-up signal requires energy and the objective of this work is to lower this signal\u27s energy consumption.;In order to achieve this, this work uses Near Field Magnetic Induction Communication technology (NFMIC) that can communicate wirelessly over short distances using low power. Using this technology, the wake-up signal will be magnetic field lines rather than an RF signal. When a source node wants to wake up its neighbors, it generates magnetic field lines disseminating as bubbles. These lines resonate across the receiver coils of neighboring nodes, thus interrupting the sleeping nodes and waking them. This idea was implemented on a node using three different NFMIC systems. Each system had different combinations of TX and RX coils and communicated using different transmitted power. The most efficient setup was determined based on the wakeup energy efficiency. Finally, this work presents the effect of obstacles on NFMIC systems by testing them on one of our NFMIC systems. As a result of this test, the various obstacles were classified into three categories based on their attenuation effect

Channel Characterisation and Link Budget of MIMO Configuration in Near Field Magnetic Communication

Traditional radio communication has gained significantly from using multiple input and multiple output (MIMO) architecture in the system. Many wireless applications, such as wireless LAN and cellular network, have adopted this technology to improve their system performance. However, the effect of MIMO systems has not been investigated in the case of inductive near field short range communications. The purpose of this paper is to explore a new method for increasing the magnetic communication range using MIMO. Three system models includingMISO, SIMO and MIMO are proposed to characterize the number of transmitters and receivers to the link. These models have helped to extend not only the range but also the communication channel in NFMIC

Enhancing the efficiency of electricity utilization through home energy management systems within the smart grid framework

The concept behind smart grids is the aggregation of “intelligence” into the grid, whether through communication systems technologies that allow broadcast/data reception in real-time, or through monitoring and systems control in an autonomous way. With respect to the technological advancements, in recent years there has been a significant increment in devices and new strategies for the implementation of smart buildings/homes, due to the growing awareness of society in relation to environmental concerns and higher energy costs, so that energy efficiency improvements can provide real gains within modern society. In this perspective, the end-users are seen as active players with the ability to manage their energy resources, for example, microproduction units, domestic loads, electric vehicles and their participation in demand response events. This thesis is focused on identifying application areas where such technologies could bring benefits for their applicability, such as the case of wireless networks, considering the positive and negative points of each protocol available in the market. Moreover, this thesis provides an evaluation of dynamic prices of electricity and peak power, using as an example a system with electric vehicles and energy storage, supported by mixed-integer linear programming, within residential energy management. This thesis will also develop a power measuring prototype designed to process and determine the main electrical measurements and quantify the electrical load connected to a low voltage alternating current system. Finally, two cases studies are proposed regarding the application of model predictive control and thermal regulation for domestic applications with cooling requirements, allowing to minimize energy consumption, considering the restrictions of demand, load and acclimatization in the system

NFMIC cooperative communication methods for body area networks

To achieve higher data rate or to extend the coverage range of a wireless communication system, cooperative relay has been seen as a promising solution. This concept has been integrated in many traditional wireless communication networks. However, it has not been extensively examined for near field magnetic induction communication (NFMIC) systems. This paper ims to apply cooperative relay to NFMIC in a sense that is applicable to body area networking, since NFMIC is stated to be a suitable physical layer for body area networks. We have shown that using idle NFMIC nodes as relaying terminals, the system performance will be enhanced, as compared to a point to point communication system. In this context we have proposed three relaying methods to enhance the data rate and the received signal power in a personal area network. The relaying strategies are denoted as MI-Relay, MAMI Relay1 and MAMI Relay2. In this paper, using theoretical studies and simulation results, we have compared the performance of the three strategies and we have shown that higher data rates can be achieved through MAMI Relay1. However, we have discussed that the separation distance between relaying nodes and the source or destination can be a key factor for relay node selection. © 2012 ACADEMY PUBLISHER