Wake-up Radio Research Articles

Compact Wake-Up Module Design Based on an Energy-Harvesting Rectenna for Wireless Sensor Receivers

A new compact energy-harvesting module is proposed with compact design techniques. The rectifying circuit eliminates the band-pass filter and matching circuit, based on an active antenna concept and a direct matching technique. For exact circuit impedance, via holes are processed with precise fabrication techniques. The implemented circuit has achieved a circuit size reduction of 76.7%. The proposed system has been applied to a wireless wake-up receiver system with excellent operating performance.

Ultralong-Range RFID-Based Wake-Up Radios for Wireless Sensor Networks

This letter presents three different strategies for waking up wireless sensor network (WSN) motes via radio frequency identification (RFID). Based on our prior work on the design of augmented ultrahigh-frequency RFID tags and ultrasensitive RF energy harvesters, the proposed solutions significantly outperform state-of-art RFID wake-up radios (both broadcast based and ID based) for WSNs. In particular, improvements up to 4.2× and 7.8× have been achieved in terms of wake-up range and wake-up delay, respectively.

IEEE 802.11‐enabled wake‐up radio system: design and performance evaluation

Today, the vast majority of personal communication devices, such as laptops, smartphones, and logically wireless fidelity (Wi-Fi) access points feature IEEE 802.11 chipsets. In turn, wake-up radio (WuR) systems are used to reduce the significant energy waste that wireless devices cause during their idle communication mode. A novel WuR system is introduced that enables any IEEE 802.11-enabled device to be used as a WuR transmitter without requiring any hardware modification. The corresponding developed WuR receiver achieves a remarkably low power consumption of 10.8 μW and operates in the Wi-Fi 2.4 GHz band. By means of thorough physical tests, it is shown that the proposed IEEE 802.11-based WuR system enables important energy savings.

Evaluation of MAC Protocols with Wake-up Radio for Implantable Body Sensor Networks

The use of wireless communication in implantable medical devices is growing rapidly due to an increasing demand for sophisticated health-care. Recently, a new type of sensor network called Implantable Body Sensor Network (IBSN) has emerged. IBSN is a network of implantable medical sensors and devices which can communicate with each other or to a base station using radio-frequency (RF) link. Wireless communication in IBSN must be extremely reliable and energy-efñcient in order to provide a long-term safe operability. The underlying MAC protocol in an RF communication is an important feature which directly affects reliability and energy-efficiency. To overeóme the high power demand of wireless communication in IBSN, the concept of wake-up radio was introduced. Some MAC protocols that can make use of wake-up radio have been proposed. This paper analyzes three of the existing MAC protocols with the wake-up feature that are suitable for IBSN, and emphasizes their strengths and weaknesses. Simulations show that performance of MAC protocols with wake-up radio varíes with different access mechanisms. Finally, we present an overview of MAC protocols with wake-up radio and discuss their practicality in implantable medical sensor networks.

Energy Optimization in Wireless Sensor Network Using Sleep Mode Transceiver

Energy efficiency is a central challenge in sensor networks, and the radio is a major contributor to overall energy node consumption. These Wireless Sensor Networks have severe resource constrains and energy conservation is very essential. The aim of this project is to reduce the energy consumption in wireless sensor networks. This paper proposes adaptive radio low-power sleep modes based on current traffic conditions in the network. It provides an analytical model to conduct a comparative study of different MAC protocols (BMAC, TMAC, SMAC, DMAC) suitable for reduction of energy consumption in wireless environment. This technique exposes the energy trade-offs of different MAC protocols. It first introduces a comprehensive node energy model, which includes energy components for radio switching, transmission, reception, listening, and sleeping for determining the optimal sleep mode and MAC protocol to use for given traffic scenarios. The model is then used for evaluating the energy-related performance of our recently proposed RFID Impulse protocol enhanced with adaptive low-power modes, and comparing it against BMAC under varying data rates. The comparative analysis confirms that RFID Impulse with adaptive low power modes provides lower energy consumption than the BMAC and DMAC in low traffic scenario. The evaluation also yields the optimal settings of low-power modes on the basis of data rates for node platform, and provides guidelines and a simple algorithm for the selection of appropriate MAC protocol, low-power mode, traffic requirements of a sensor network application. Index Terms: RFID, wake-up radio, sleep mode, adaptive, energy efficiency, MAC protocols, routing protocols, energy model, sensor networks.

Power Consumption of Integrated Low-Power Receivers

With the advent of Internet of Things (IoT) it has become clear that radio-frequency (RF) designers have to be aware of power constraints, e.g., in the design of simplistic ultra-low power receivers often used as wake-up radios (WuRs). The objective of this work, one of the first systematic studies of power bounds for RF-systems, is to provide an overview and intuitive feel for how power consumption and sensitivity relates for low-power receivers. This was done by setting up basic circuit schematics for different radio receiver architectures to find analytical expressions for their output signal-to-noise ratio including power consumption, bandwidth, sensitivity, and carrier frequency. The analytical expressions and optimizations of the circuits give us relations between dc-energy-per-bit and receiver sensitivity, which can be compared to recent published low-power receivers. The parameter set used in the analysis is meant to reflect typical values for an integrated 90 nm complementary metal-oxide-semiconductor fabrication processes, and typical small sized RF lumped components.

Performance Evaluation and Comparative Analysis of SubCarrier Modulation Wake-up Radio Systems for Energy-Efficient Wireless Sensor Networks

Energy-efficient communication is one of the main concerns of wireless sensor networks nowadays. A commonly employed approach for achieving energy efficiency has been the use of duty-cycled operation of the radio, where the node's transceiver is turned off and on regularly, listening to the radio channel for possible incoming communication during its on-state. Nonetheless, such a paradigm performs poorly for scenarios of low or bursty traffic because of unnecessary activations of the radio transceiver. As an alternative technology, Wake-up Radio (WuR) systems present a promising energy-efficient network operation, where target devices are only activated in an on-demand fashion by means of a special radio signal and a WuR receiver. In this paper, we analyze a novel wake-up radio approach that integrates both data communication and wake-up functionalities into one platform, providing a reconfigurable radio operation. Through physical experiments, we characterize the delay, current consumption and overall operational range performance of this approach under different transmit power levels. We also present an actual single-hop WuR application scenario, as well as demonstrate the first true multi-hop capabilities of a WuR platform and simulate its performance in a multi-hop scenario. Finally, by thorough qualitative comparisons to the most relevant WuR proposals in the literature, we state that the proposed WuR system stands out as a strong candidate for any application requiring energy-efficient wireless sensor node communications.

Design, development, and performance evaluation of a low-cost, low-power wake-up radio system for wireless sensor networks

Energy-efficient operation is a challenge for wireless sensor networks (WSNs). A common method employed for this purpose is duty-cycled operation, which extends battery lifetime yet incurs several types of energy wastes and challenges. A promising alternative to duty-cycled operation is the use of wake-up radio (WuR), where the main microcontroller unit (MCU) and transceiver, that is, the two most energy-consuming elements, are kept in energy-saving mode until a special signal from another node is received by an attached, secondary, ultra-low power receiver. Next, this so-called wake-up receiver generates an interrupt to activate the receiver node's MCU and, consequently, the main radio. This article presents a complete wake-up radio design that targets simplicity in design for the monetary cost and flexibility concerns, along with a good operation range and very low power consumption. Both the transmitter (WuTx) and the receiver (WuRx) designs are presented with the accompanying physical experiments for several design alternatives. Detailed analysis of the end system is provided in terms of both operational distance (more than 10 m) and current consumption (less than 1 μA). As a reference, a commercial WuR system is analyzed and compared to the presented system by expressing the trade-offs and advantages of both systems.

Passive wake-up radios: From devices to applications

Energy efficiency is one of the most important criteria in the design of a wireless sensor network. Sensor nodes are usually battery-powered and thus have very limited lifetime. In this paper, we introduce a novel passive wake-up radio device named WISP-Mote that uses a passive RFID tag as a wake-up receiver for a traditional sensor node. We characterize the WISP-Mote with field tests in different operating environments and present the wake-up probabilities based on the distance between the wake-up transmitter and receiver. We then perform simulations to compare the performance of a network with WISP-Motes and with duty-cycling of the sensor nodes, using the wake-up probabilities measured in our field tests. Additionally, potential applications that can benefit from WISP-Motes are discussed, and the advantages of using WISP-Motes are identified by simulation results based on these application scenarios. Results show that the wake-up radio sensor networks have great potential over duty-cycling approaches for energy efficiency, while providing similar latency and packet delivery performances.

Wake-up radio architecture utilizing passive down conversion mixing

This letter describes a low-energy wake-up radio that is based on passive down conversion. The receiver activates when it receives two closely located frequencies that are down converted in the passive mixer. The down converted signal is applied to a low-frequency wake-up IC that provides an identification code and wakes up an active radio for further communication. This letter derives an expression for the voltage sensitivity of the mixer and verifies the concept experimentally at 2.45 GHz. The wake-up radio consumes 6.8 μA at 3 V. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1038–1041, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27493

A 4.4-$\mu$W Wake-Up Receiver Using Ultrasound Data

In wireless sensor nodes, using a wake-up receiver to duty-cycle the main receiver significantly reduces the overall power consumption of the node, as long as the power consumption of the always-ON wake-up receiver is very low. We demonstrate line-of-sight ultrasound data communications for ultra-low power wireless wake-up in sensor networks. The 65-nm CMOS 0.6-V receiver prototype achieves a BER of better than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> measured for a 250-bps free-space 8.6-m link in an indoor environment while dissipating only 4.4 μ W and requiring only - 18 dBm electrical power to be delivered to the transmit transducer.

A Low-Power Wakeup Radio for Application in WSN-Based Indoor Location Systems

This paper presents a low-power wakeup radio (WUR) for application in indoor location systems. The presented radio has a better performance than the state-of-the-art radios, since it has low-power consumption, only 10 μW and it is perfectly integrated into a wireless sensor network based on ZigBee, which is used for location purposes. This performance was achieved due to an optimised radio frequency design of the WUR, which was embedded with a low-cost/low-power processor, and due to an enhanced control algorithm. Moreover, a software defined radio approach has been used to implement the WUR protocol. The WUR was designed and integrated in an existing WSN-based indoor location system which was originally based on a periodic sleep-wake up duty-cycled protocol. In the WUR protocol the location sensor is kept in deep sleep mode until it receives an external wake-up order. According to estimates, with this scheme, the battery lifetime can be increased from 200 days (using conventional duty-cycle protocol) up to almost 8000 days (sensor waken-up few times per day).

Energy Efficient MAC Protocol for Low-Energy Critical Infrastructure Monitoring Networks Using Wakeup Radio

Critical infrastructure monitoring applications are rapidly increasing. Application requirements include reliable data transfer, energy efficiency, and long deployment lifetime. These applications must also be able to operate in an extremely low-cost communication environment in order to be attractive to potential users. A low rate wireless personal area network can help control and manage the operations of such applications. In this paper, we present a medium access control (MAC) protocol for low-energy critical infrastructure monitoring (LECIM) applications. The proposed MAC protocol is based on a framed slotted aloha multiple access schemes. For downlink communication, we use a wakeup radio approach to avoid complex bookkeeping associated with the traditional MAC protocols. Analytical expressions for power consumption and delay are derived to analyze and compare the performance of our proposed protocol with the existing well-known T-MAC, B-MAC, X-MAC, ZigBee, and WiseMAC protocols. It is shown that our proposed protocol outperforms all the other protocols in terms of power consumption and delay.

A power efficient MAC protocol for wireless body area networks

Abstract Applications of wearable and implanted wireless sensor devices are hot research area. A specialized field called the body area networks (BAN) has emerged to support this area. Managing and controlling such a network is a challenging task. An efficient media access control (MAC) protocol to handle proper management of media access can considerably improve the performance of such a network. Power consumption and delay are major concerns for MAC protocols in a BAN. Low cost wakeup radio module attached with sensor devices can help reduce power consumption and prolong the network lifetime by reducing idle state power consumption and increasing sleep time of a BAN node. In this article, we propose a new MAC protocol for BAN using out of band (on-demand) wakeup radio through a centralized and coordinated external wakeup mechanism. We have compared our method against some existing MAC protocols. Our method is found to be efficient in terms of power consumption and delay.

Nano-Power Wireless Wake-Up Receiver With Serial Peripheral Interface

We designed, implemented, tested and measured an ultra low power Wake Up Receiver (WUR), intended for use in Wireless Body Area Networks (WBAN). Gaussian On-Off Keying (GOOK) and Pulse Width Modulation (PWM) are used to modulate and encode, respectively, the preamble signal. The receiver incorporates a decoder to enable Serial Peripheral Interface (SPI). WUR was also comprehensively tested for power consumption and robustness to RF interference from wireless devices commonly found in the vicinity of persons utilising WBAN technology. Our results and comparative evaluation demonstrate that the achieved listening power of 270nW for the Wake Up Receiver is significantly lower power consumption than for the other state-of-the-art. The proposed preamble detection scheme can significantly reduce false wake ups due to other wireless devices in a WBAN. Additionally, SPI significantly reduces the overall power consumption for packet reception and decoding.

A Simulation Study of TaMAC Protocol using Network Simulator 2

A Wireless Body Area Network (WBAN) is expected to play a significant role in future healthcare system. It interconnects low-cost and intelligent sensor nodes in, on, or around a human body to serve a variety of medical applications. It can be used to diagnose and treat patients with chronic diseases such as hypertensions, diabetes, and cardiovascular diseases. The lightweight sensor nodes integrated in WBAN require low-power operation, which can be achieved using different optimization techniques. We introduce a Traffic-adaptive MAC protocol (TaMAC) for WBAN that supports dual wakeup mechanisms for normal, emergency, and on-demand traffic. In this letter, the TaMAC protocol is simulated using a well-known Network Simulator 2 (NS-2). The problem of multiple emergency nodes is solved using both wakeup radio and CSMA/CA protocol. The power consumption, delay, and throughput performance are closely compared with beacon-enabled IEEE 802.15.4 MAC protocol using extensive simulations.

High sensitivity wake-up radio using spreading codes: design, evaluation, and applications

Most of the published wake-up radios propose low energy design at the expense of reduced radio range, which means that they require an increased deployment density of sensor networks. In this article, we introduce a design of a high sensitivity 916.5 MHz wake-up radio using low data rate and forward error correction (FEC). It improves the sensitivity, up to -122 dBm at a data rate 370 bit/s. It achieves up to 13 dB of coding gain with symbol error rate (SER) 10-2, and up to 4 times the range of the data radio, rendering it more suitable to sensor networks. Our design can receive wake-up signal reliably from any IEEE 802.15.4 transmitter and achieves a low packet error rate (PER) 0.0159 at SNR 4 dB. Furthermore, our design encodes the node ID into a wake-up signal to avoid waking up the undesired nodes.

Effect of Hash Function on Performance of Low Power Wake up Receiver for Wireless Sensor Network

Next generation network will consist of different types of wireless networks like WSN, Wi-Fi, WiMAX, UMTS, LTE and etc. Wireless Sensor Network (WSN) finds unique and special application as compared to the said networks because sensors are deployed in a very secret, awkward and hostile environment like battle field etc. Various wireless sensor nodes are interconnected and form a Wireless Sensor Network. Sensor nodes once deployed in a region, can’t be repaired thus the power system deployed in the nodes becomes a major key issue i.e. how long its battery life can be utilised. Another major issue of WSN is to have a more secured network which is a function of hash keys. Increase usage of hash key means enhanced security but at the cost of power and area. Sensor systems must utilize the minimal possible energy while operating over secured and wide range of operating scenarios. In this paper, we have proposed a novel ID matching mechanism that uses a Bloom filter to realize wake-up wireless communication. Paper uses hash function for uniquely recognizing particular sensor- node- cluster among all clusters. Paper also shows the effect of number of hash functions on performance of wireless sensor node. The design and implementation of a wireless wake-up receiver module simulation reveals that proposed model consume 724nW dynamic power and with bloom filter, the proposed model consumes dynamic power 85% less than the consumption cited in “Takiguchi” model [1] . Dynamic power is further reduced by 10% when parallel processing is implemented. Finally paper provides a novel approach to save the dynamic power and subsequently increases the battery life of wireless sensor node and network as a whole.

An Ultra Low-power and Traffic-adaptive Medium Access Control Protocol for Wireless Body Area Network

Wireless Body Area Network (WBAN) consists of low-power, miniaturized, and autonomous wireless sensor nodes that enable physicians to remotely monitor vital signs of patients and provide real-time feedback with medical diagnosis and consultations. It is the most reliable and cheaper way to take care of patients suffering from chronic diseases such as asthma, diabetes and cardiovascular diseases. Some of the most important attributes of WBAN is low-power consumption and delay. This can be achieved by introducing flexible duty cycling techniques on the energy constraint sensor nodes. Stated otherwise, low duty cycle nodes should not receive frequent synchronization and control packets if they have no data to send/receive. In this paper, we introduce a Traffic-adaptive MAC protocol (TaMAC) by taking into account the traffic information of the sensor nodes. The protocol dynamically adjusts the duty cycle of the sensor nodes according to their traffic-patterns, thus solving the idle listening and overhearing problems. The traffic-patterns of all sensor nodes are organized and maintained by the coordinator. The TaMAC protocol is supported by a wakeup radio that is used to accommodate emergency and on-demand events in a reliable manner. The wakeup radio uses a separate control channel along with the data channel and therefore it has considerably low power consumption requirements. Analytical expressions are derived to analyze and compare the performance of the TaMAC protocol with the well-known beacon-enabled IEEE 802.15.4 MAC, WiseMAC, and SMAC protocols. The analytical derivations are further validated by simulation results. It is shown that the TaMAC protocol outperforms all other protocols in terms of power consumption and delay.

Impulse-Based Scheme for Crystal-Less ULP Radios

This study describes a method of implementing a fully integrated ultra-low-power (ULP) radio for wireless sensor networks (WSNs). This is achieved using an ad hoc modulation scheme (impulse radio), with a bandwidth of 17.7 MHz in the 2.4 GHz-ISM band and a specific medium access control (MAC) protocol, based on a duty-cycled wake-up radio and a crystal-less clock generator. It is shown that the total average power consumption is expected to be less than 100 ¿W with a clock generator inaccuracy of only 1%.