SENSORNETS 2015 Abstracts


Area 1 - Sensor Networks Software and Architectures

Full Papers
Paper Nr: 14
Title:

RIOT OS Paves the Way for Implementation of High-performance MAC Protocols

Authors:

Kévin Roussel, Ye-Qiong Song and Olivier Zendra

Abstract: Implementing new, high-performance MAC protocols requires real-time features, to be able to synchronize correctly between different unrelated devices. Such features are highly desirable for operating wireless sensor networks (WSN) that are designed to be part of the Internet of Things (IoT). Unfortunately, the operating systems commonly used in this domain cannot provide such features. On the other hand, “bare-metal” development sacrifices portability, as well as the multitasking abilities needed to develop the rich applications that are useful in the domain of the Internet of Things. We describe in this paper how we helped solving these issues by contributing to the development of a port of RIOT OS on the MSP430 microcontroller, an architecture widely used in IoT-enabled motes. RIOT OS offers rich and advanced real-time features, especially the simultaneous use of as many hardware timers as the underlying platform (microcontroller) can offer. We then demonstrate the effectiveness of these features by presenting a new implementation, on RIOT OS, of S-CoSenS, an efficient MAC protocol that uses very low processing power and energy.

Paper Nr: 20
Title:

Resource-aware State Estimation in Visual Sensor Networks with Dynamic Clustering

Authors:

Melanie Schranz and Bernhard Rinner

Abstract: Generally, resource-awareness plays a key role in wireless sensor networks due the limited capabilities in processing, storage and communication. In this paper we present a resource-aware cooperative state estimation facilitated by a dynamic cluster-based protocol in a visual sensor network (VSN). The VSN consists of smart cameras, which process and analyze the captured data locally. We apply a state estimation algorithm to improve the tracking results of the cameras. To design a lightweight protocol, the final aggregation of the observations and state estimation are only performed by the cluster head. Our protocol is based on a marketbased approach in which the cluster head is elected based on the available resources and a visibility parameter of the object gained by the cluster members. We show in simulations that our approach reduces the costs for state estimation and communication as compared to a fully distributed approach. As resource-awareness is the focus of the cluster-based protocol we can accept a slight degradation of the accuracy on the object’s state estimation by a standard deviation of about 1.48 length units to the available ground truth.

Paper Nr: 33
Title:

Indoor Sensor Placement for Diverse Sensor-coverage Footprints

Authors:

Masoud Vatanpour Azghandi, Ioanis Nikolaidis and Eleni Stroulia

Abstract: Single occupant localization in an indoor environment can be accomplished by the deployment of, properly placed, motion sensors. In this paper, we address the problem of cost-efficient sensor placement for highquality indoor localization, taking into account sensors with diverse coverage footprints, and the occlusion effects due to obstructions typically found in indoor environments. The objective is the placement of the smallest number of sensors with the right combination of footprints. To address the problem, and motivated by the vast search space of possible placement and footprint combinations, we adopt an evolutionary technique. We demonstrate that our technique performs faster and/or produces more accurate results (depending on the application) when compared to previously proposed greedy methods. Furthermore, our technique is flexible in that adding new sensor footprints can be trivially accomplished.

Paper Nr: 56
Title:

Sense2Health - A Quantified Self Application for Monitoring Personal Exposure to Environmental Pollution

Authors:

Sara Hachem, Georgios Mathioudakis, Animesh Pathak, Valerie Issarny and Rajiv Bhatia

Abstract: Sense2Health is a Quantified Self application that monitors personal exposure to environment pollution and assesses its heath-related risks. The novelty of the application is that it requires little to no active involvement by users and unlike existing applications, it correlates the individual’s well-being to their environment as opposed to their physical activity alone. Consequently, when health and environment data are acquired, our application enables users to better identify behavior changes towards enhancing their health by enhancing their environments. Furthermore, Sense2Health is an open platform for integrating existing domain-specific sensing applications (environmental and health monitoring) focused on decreasing required specialized development efforts. We present in this paper the design of Sense2Health in addition to a proof-of-concept implementation for a noise-monitoring use case. Afterwards, we assess its performance while integrating it with a dedicated open source noise sensing application.

Short Papers
Paper Nr: 10
Title:

Solving Sensor Void Problem in Uncontrolled Mobile Sensor Networks - Development of Mobile Sensor Database Systems

Authors:

Soo Seok Park, Chong Sok Lim and Soon J. Hyun

Abstract: Due to the random movement of sensor nodes in uncontrolled mobile sensor networks, the distribution of sensor nodes may not be uniform over the area of network coverage. Querying a target space in which mobile sensors are unavailable at the time of the data request will lead to no return of the result. In this paper, this problem is referred to as sensor void problem, which leads to difficulties in data management and application design activities. We address the sensor void problem and offer solutions with a location-aware time-constrained query processing strategy. The key idea of the proposed strategy is to allow mobile sensor nodes to keep track of time validity and target location matching checks for the execution of the queries received from the base station. Programmers can specify a certain degree of time sensitivity in their queries according to their applications’ semantics. We implemented the proposed mobile query processing scheme into our previously developed sensor database system. A performance evaluation shows how the proposed query processing strategy effectively handles the sensor void problem with various parameters of an uncontrolled mobile sensor network.

Paper Nr: 24
Title:

A Multi-stage Graph Approach for Efficient Clustering in Self-Organized Wireless Sensor Networks

Authors:

Abhishek Karpate and Hesham Ali

Abstract: With the rapid increase in applications utilizing the current advancements of wireless sensor networks, a number of problems related to self-organization, energy-awareness and network organizations have attracted many researchers in the field. Various groups have proposed grouping the sensors into clusters and design communication routes in two levels as a way to improve communication cost and better organize networks of large sensors. In this paper, we propose a new approach to cluster wireless sensors and identify cluster heads using multi-stage graph algorithms. The approach takes advantage of the optimally associated with finding matching solutions in multi-stage graph networks. The proposed solution is designed to accommodate networks with different sizes and levels of density. We tested the algorithm using different types of networks and measure the quality of the key parameters as compared to those obtained by traditional greedy heuristics. Obtained results show that the multi-stage graph approach produces better network organization and better cluster head selection which leads to be more efficient self-organized networks.

Paper Nr: 31
Title:

Study of Timing Properties on Data Collection and Query Processing Techniques in Wireless Sensor Networks

Authors:

Abderrahmen Belfkih, Bruno Sadeg, Claude Duvallet and Laurent Amanton

Abstract: The real-time aspect is an important factor for Wireless Sensor Network (WSN) applications, which demand a timely data delivery, to reflect the current state of the environment. However, most existing works in the field of sensor networks are only interested in data processing and energy consumption, to improve the lifetime of WSN. Extensive researches have been done on data processing in WSN. Some works have been interested in improving data collection methods, and others have focused on various query processing techniques. In recent years, the query processing using abstract database technology like Cougar and TinyDB have shown efficient results in many researches. This paper presents a study of timing properties through two data processing techniques forWSN. The first is based on a warehousing approach, in which data are collected and stored on a remote database. The second is based on query processing using an abstract database like TinyDB. This study has allowed us to identify some factors which enhance the respect of temporal constraints.

Paper Nr: 55
Title:

Time-variant Adaptive Passive Time Reversal Equaliser and a Perspective for Environmental Focusing Method

Authors:

Lussac P. Maia, António Silva and Sérgio M. Jesus

Abstract: High digital data throughput in Underwater Acoustic Communications (UAComm) is a challenging subject, specially in shallow water where the channel is a wave-guide causing multipath propagation and where Doppler effect usually occurs due to relative source-receiver motion jointly to ocean dynamics. The source and receiver sensors can be used for telemetry in point-to-point underwater communications or as nodes of an underwater acoustic network within the scope of oceanic research observatory or offshore activities. However, channel tracking is required for reliable digital underwater communications between the sensors, which is a hard task due to the complicated propagation of acoustic waves in the ocean. Equalisation is often required to perform a compensation method aiming to overcome the inter-symbol interference (ISI) caused by multipath propagation. The motivation of this work is to propose a compensation method deploying the adaptive passive time-reversal (ApTR) equaliser, aiming to perform ISI mitigation jointly to Doppler compensation in time-variant channels. The benefit given by ApTR processing would be the performance improvement in underwater communications between an active sensor and a vertical line array of receiver sensors, relying in well-succeed time-variant channel impulse response estimation. Furthermore, this position paper discusses the perspective of use an environmental focusing method for channel estimation within the ApTR equaliser, based on the idea that a set of oceanic acoustic physical parameters – which are generally estimated in low-frequency matched field processing problems like geoacoustic assessment, ocean tomography and source localization – could be conveniently used for channel compensation in high frequency underwater communications using a carefully chosen search space of replicas. The results are two fold: in one hand the equalisation shall improve the UAComm system, and in the other hand, the best match of channel parameters consequently yields a refined local environmental assessment.

Posters
Paper Nr: 27
Title:

Efficient Power Consumption Strategies for Stationary Sensors Connected to GSM Network

Authors:

Gabor Paller, Péter Szármes and Gábor Élő

Abstract: The number of large sensor systems are rapidly growing nowadays in many fields. Well-designed Big Data solutions are able to manage the enormous data flow and create real business benefits. One dynamically growing application area is precision farming. It requires robust and energy-efficient sensors, because the devices are placed outdoors, often in harsh conditions, and there is no power outlet in the middle of a corn field. Power efficiency is one of the major themes of the Internet of Things (IoT). According to the IoT vision, embedded sensors send their data to processing units (either located near to the sensor or on some intermediate gateway device or in the cloud) using heterogeneous transport networks. Some sensors employ short-range network like Bluetooth and some gateway device like a tablet. Other sensors directly connect to wide-area networks like cellular networks. This paper will analyse different communication patterns accomplished over GSM network from the viewpoint of the energy consumption of the sensor device with the assumption that the sensor is stationary. The measurements were done using two different GSM modems designed for embedded systems to ensure that the results represent a wider picture and not some implementation property of a particular GSM modem. Recommendations are given about the strategies applications should follow in order to minimize the energy consumption of their GSM subsystems.

Paper Nr: 30
Title:

An Adaptive Pre-detection Based RFID Tag Anti-collision Scheme

Authors:

Chiu-Kuo Liang and Yuan-Cheng Chien

Abstract: One of the research areas in RFID systems is a tag anti-collision protocol; how to reduce identification time with a given number of tags in the field of an RFID reader. There are two types of tag anti-collision protocols for RFID systems: tree based algorithms and slotted aloha based algorithms. Many anti-collision algorithms have been proposed in recent years, especially in tree based protocols. However, there still have challenges on enhancing the system throughput and stability due to the underlying technologies had faced different limitation in system performance when network density is high. Particularly, the tree based protocols had faced the long identification delay. Recently, a Hybrid Hyper Query Tree (H2QT) protocol, which is a tree based approach, was proposed and aiming to speedup tag identification in large scale RFID systems. The main idea of H2QT is to track the tag response and try to predict the distribution of tag IDs in order to reduce collisions. In this paper, we propose a pre-detection tree based algorithm, called the Adaptive Pre-Detection Based Query Tree algorithm (APDBQT), to avoid those unnecessary queries. Our proposed APDBQT protocol can reduce not only the collisions but the idle cycles as well by using pre-detection mechanism. The simulation results show that our proposed technique provides superior performance in high density environments. It is shown that the APDBQT is effective in terms of increasing system throughput and minimizing identification delay.

Paper Nr: 48
Title:

Social-based Forwarding of Messages in Sensor Networks

Authors:

Basim Mahmood, Marcello Tomasini and Ronaldo Menezes

Abstract: As we adopt the Internet of Things (IoT), the boundaries between sensor and social networks are likely to disappear. However, to this date, the use of social networks in the design of wireless sensor network protocols has not received much attention. In this paper, we focus on the concept of information dissemination in a framework where sensors are carried by people who are part of a social network. We propose two social-based forwarding approaches for what has been called Social Network of Sensors (SNoS). To this end, we exploit two important characteristics of ties in social networks, namely strong ties and weak ties. The former is used to achieve rapid dissemination to nearby sensors while the latter aims at dissemination to faraway sensors.

Paper Nr: 52
Title:

The Automagic Box of Beauty - A Prototypical Smart Device as Use Case Example for User-centered Decision Support via the Hub-of-all-Things

Authors:

Helen Oliver

Abstract: In this position paper we present the Automagic Box of Beauty, a prototype smart cabinet which enables the user to track their rate of consumption of toiletries. By transmitting product consumption data from the box to the Hub-of-all-Things (HAT), a platform for personal data that is fully owned and controlled by the individual, we open the potential for decision support for the user that hitherto has only been available at the enterprise level. By returning ownership of personal data to the individual, the HAT enables horizontal integration of information that has until now been held in vertical silos. We show how, by contextualizing the product consumption data with data from a variety of other sensors and sources, the system will support individual users in making decisions – in this use case example, decisions about replenishment and selection of the products in the box.

Paper Nr: 53
Title:

Evaluation of a Fault-tolerant WSN Routing Algorithm Based on Link Quality

Authors:

Unai Burgos, Iratxe Soraluze and Alberto Lafuente

Abstract: In this paper we propose a fault-tolerant routing algorithm for WSN. Our approach is based on link quality as the main criteria to build an initial routing tree, although additional criteria, such as node reachability and path diversity, are also considered. The routing tree is built using only local information (two-hop neighbourhood). This information is also used to reconfigure locally the routing tree when a fault is detected. The routing algorithm has been implemented using the OMNeT++ simulator and a preliminary performance evaluation has been carried out. Results show that our algorithm reach comparable delivery rates than a standard flooding algorithm, being much more efficient.

Area 2 - Wireless Information Networks

Full Papers
Paper Nr: 5
Title:

Refracted Acoustic Communications in Wireless Underwater Sensor Networks with Mobility

Authors:

S. Blouin, M. Barbeau and E. Kranakis

Abstract: Routing is a fundamental function of any wireless network. For battery-powered underwater sensors using acoustic waves, routing is even more challenging due to an ever changing and communication-opaque ocean. Herein, we propose a shallow-water routing scheme that adapts to a unique physical phenomena of the medium. In particular, the proposed routing exploits downward and upward refractions for underwater networks comprising mobile nodes. Solutions for node-to-node links are developed before extending the concept to network routing. In particular, necessary and sufficient conditions guaranteeing the existence of a single-hop link through acoustic refraction are derived. Simulations convey results followed by concluding remarks.

Paper Nr: 23
Title:

Using a Token Approach for the MAC Layer of Linear Sensor Networks - Impact of the Redundancy on the Throughput

Authors:

El Hadji Malick Ndoye, Frédérique Jacquet, Michel Misson and Ibrahima Niang

Abstract: Wireless Sensor Networks (WSNs) consist of a large number of sensor nodes deployed in a wide area for monitoring applications. For some of these applications, as pipeline or road monitoring, wireless sensor nodes have to be deployed in a linear manner. We refer to these WSNs as Linear Sensor Networks (LSNs). Due to specificity of LSNs, MAC protocol designed for WSNs, as contention or TDMA based protocols, are often not suitable. Furthermore, wireless node deployment can provide a certain form of redundancy to prevent link or node failures. In this paper, we propose a token based MAC protocol for linear sensor networks in order to improve the network performance. We evaluate the effect of the redundancy on the number of packets delivered to the sink. We show that the redundancy induces a significant improvement both on the delivered traffic and on the FIFO queue size of the nodes.

Paper Nr: 36
Title:

Protecting Informative Messages over Burst Error Channels in Chain-based Wireless Sensor Networks

Authors:

Zahra Taghikhaki, Nirvana Meratnia and Paul Havinga

Abstract: Regardless of the application, the way that data and information are disseminated is an important aspect in Wireless Sensor Networks (WSNs). The wireless data dissemination protocol should often guarantee a minimum reliability requirement. In this regard and to well-balance the energy and reliability, the more important packets should be protected by more powerful error control codes than the less important ones. This information-aware capability allows a system to deliver critical information with high reliability but potentially at a higher resource cost. In this paper, we first find and evaluate the factors that may influence the importance level of a packet and then design an error control approach by adaptively selecting codes for each individual links which experience long-term-fading and for each individual packet at run-time instead of applying network-wide settings prior to deployment. Moreover, we target the poor-explored chain-based topology that is of interest for many applications (e.g. monitoring bridge, tunnel, etc.). Simulation results validate the superiority of our approach compared with a number of Reed-Solomon-based error control approaches.

Short Papers
Paper Nr: 25
Title:

A Proposal for Network Coding with the IEEE 802.15.6 Standard

Authors:

Xiaomeng Shi and Muriel Médard

Abstract: We examine the Medium Access Control sublayer of the IEEE 802.15.6 Wireless Body Area Network (WBAN) standard, and propose minor modifications to the standard so that linear random network coding can be included to help improve energy efficiency and throughput of WBANs compatible with the standard. Both generation-based and sliding window approaches are possible, and a group-block acknowledgment scheme can be implemented by modifying block acknowledgment control type frames. Discussions on potential energy and throughput advantages of network coding are provided.

Posters
Paper Nr: 54
Title:

Tunable Transmission Power to Improve 2D RSSI Based Localization Algorithm

Authors:

D. Polese, L. Pazzini, A. Minotti, L. Maiolo and A. Pecora

Abstract: Radio frequency wireless technology is surely one of the most used technologies in indoor localization. RF-signals have been utilized in several ways to estimate the distances among the anchor nodes and the mobile nodes and, probably the methods based on the measure of the Received Signal Strength (RSS) are the most explored ones. RSS depends on the transmission medium and environment and this affects also the distance measurement performances. To mitigate the external influences, transmission parameters, as for example the transmission channel and transmission power, can be tuned. To this purpose, in this work the influence of the power transmission on the localization algorithm performance is investigated. In particular a method to select the power transmission that allows the best localization performance is presented. The results show that the localization performance depend on the transmission power. Moreover, a method to establish the best power transmission for the specific environment is presented and tested.

Area 3 - Data Manipulation

Short Papers
Paper Nr: 21
Title:

Prediction-aided Radio-interferometric Object Tracking

Authors:

Gergely Zachár and Gyula Simon

Abstract: In this paper a novel robust radio-interferometric object tracking method is proposed. The system contains fixed infrastructure transmitter nodes generating interference signals, the phases of which are measured by the tracked receivers and other fixed infrastructure nodes. From the measured phase values a confidence map is computed, which is used to generate the track of the moving receivers. The proposed method enhances the track estimation by an adaptive evaluation method of the confidence map, and also provides more robust estimation by allowing bad or missing measurements, which are tolerated by predictions extracted from the evolution of the confidence map in time. The performance of the proposed system is illustrated by real measurements.

Paper Nr: 41
Title:

A New Kernel for Outlier Detection in WSNs Minimizing MISE

Authors:

Rohit Jain, C. P. Gupta and Seema Sharma

Abstract: In sensor network, data generated by various sensors deployed at different locations need to be analyzed in order to identify interesting events correspond to outliers. The presence of outliers may distort contained information. To ensure that the information is correctly extracted, it is necessary to identify the outliers and isolate them during knowledge extraction phase. In this paper, we propose a novel unsupervised algorithm for detecting outliers based on density by coupling two principles: first, kernel density estimation and second assigning an outlier score to each object. A new kernel function building a smoother version of density estimate is proposed. An outlier score is assigned to each object by comparing local density estimate of each object to its neighbors. The two steps provide a framework for outlier detection that can be easily applied to discover new or unusual types of outliers. Experiments performed on synthetic and real datasets suggest that the proposed approach can detect outliers precisely and achieve high recall rates which in turn demonstrate the potency of the proposed approach.

Paper Nr: 51
Title:

Sensor-data Analytics in Cyber Physical Systems - From Husserl to Data Mining

Authors:

Paul O'Leary, Matthew Harker and Chrostoph Gugg

Abstract: This position paper proposes a discussion of the need for a solid philosophical basis for mining sensor-data based on phenomenology. Additionally it is proposed that, when considering cyber physical systems, the solution of inverse problems is a prerequisite if the results are to have physical meaning. A prototype lexical analysis tool for sensor-data is presented and its application to knowledge discovery in large mechatronic systems is demonstrated.

Area 4 - Obstacles

Full Papers
Paper Nr: 50
Title:

Research on Payload Aggregation of Packets in WSNs

Authors:

Ákos Milánkovich, Gergely Ill, Károly Lendvai, Sándor Imre and Sándor Szabó

Abstract: Creating wireless sensor networks requires a different approach than traditional communication networks because energy efficiency plays a key role in sensor networks, which consist of devices without external power. The amount of energy used determines the lifetime of these devices. In most cases data packets are less sensitive to delay, thus can be aggregated, making it possible to gather more useful information reducing the energy required to transmit information. This article discusses the energy efficiency of different Forward Error Correction algorithms and presents a method to calculate the optimal amount of aggregation of the data packets in terms of power consumption, while taking into account the Bit Error Rate characteristics of the wireless channel. The contribution of this paper is a general method to improve the energy efficiency of wireless sensor networks by using the optimal amount of aggregation in case of different FEC codes and channel characteristics. The presented results can be applied to any packet-based wireless protocol.

Posters
Paper Nr: 28
Title:

Key Establishment and Trustful Communication for the Internet of Things

Authors:

Davi Resner and Antônio Augusto Fröhlich

Abstract: This work describes a practical solution for the problem of cryptographic key establishment and secure communication in the context of the Internet of Things, in which computational efficiency is a fundamental requirement. A symmetric-key establishment protocol based on AES, Poly1305-AES, time synchronization, Elliptic Curve Diffie-Hellman and sensor IDs is proposed to achieve data confidentiality, authentication, integrity and prevention from replay attacks. Such a protocol was implemented in the EPOS operating system in the form of a network layer that transparently provides trustfulness. Tests were executed on the EPOSMoteII platform and the analysis of the results shows that the implementation is adequate to be used in the scenario of embedded systems with low processing power.

Area 5 - Applications and Uses

Full Papers
Paper Nr: 7
Title:

Classification of Air Quality Inside Car Cabin using Sensor System

Authors:

Andrzej Szczurek and Monika Maciejewska

Abstract: Daily practice, but also research, show that poor indoor air quality (IAQ) is a serious problem in many vehicles. In this work we present an approach to the evaluation of air quality in car cabin. It consists in IAQ classification. We focussed on defining classes in a way which may be useful for improving air quality during a trip. In order to assure the provision of objective information, IAQ classes are specified with reference to measurable parameters of indoor air. The parameters: temperature, relative humidity, CO2 concentration and VOC content indicator are considered jointly. Class assignment is realized on a software level, based on the measurement data provided by the sensor module located inside car cabin. The final announcement received by the driver refers to the class of indoor air. It informs about: thermal conditions, air humidity and air freshness. These components correspond to the capabilities of air handling system in the car and they were included in the message to provide hints for improving air quality. The information is delivered in real time. We believe, the implementation of the presented approach will contribute to the improvement of car microenvironment upon driving.

Paper Nr: 16
Title:

A Personalized Rehabilitation System based on Wireless Motion Capture Sensors

Authors:

Pedro Macedo, José Afonso and Ricardo Simões

Abstract: We live in an aging society, an issue that will be exacerbated in the coming decades, due to low birth rates and increasing life expectancy. With the decline in physical and cognitive functions with age, it is of the utmost importance to maintain regular physical activity, in order to preserve an individual’s mobility, motor capabilities and coordination. Within this context, this paper describes the development of a wireless sensor network and its application in a human motion capture system based on wearable inertial and magnetic sensors. The goal is to enable, through continuous real-time monitoring, the creation of a personalized home-based rehabilitation system for the elderly population and/or injured people. Within this system, the user can benefit from an assisted mode, in which their movements can be compared to a reference motion model of the same movements, resulting in visual feedback alerts given by the application. This motion model can be created previously, in a ‘learning phase’, under supervision of a caregiver.

Short Papers
Paper Nr: 6
Title:

AIRWISE - An Airborne Wireless Sensor Network for Ambient Air Pollution Monitoring

Authors:

Orestis Evangelatos and José D. P. Rolim

Abstract: Over the last decades with the rapid growth of industrial zones, manufacturing plants and the substantial urbanization, environmental pollution has become a crucial health, environmental and safety concern. In particular, due to the increased emissions of various pollutants caused mainly by human sources, the air pollution problem is elevated in such extent where significant measures need to be taken. Towards the identification and the qualification of that problem, we present in this paper an airborne wireless sensor network system for automated monitoring and measuring of the ambient air pollution. Our proposed system is comprised of a pollution-aware wireless sensor network and unmanned aerial vehicles (UAVs). It is designed for monitoring the pollutants and gases of the ambient air in three-dimensional spaces without the human intervention. In regards to the general architecture of our system, we came up with two schemes and algorithms for an autonomous monitoring of a three-dimensional area of interest. To demonstrate our solution, we deployed the system and we conducted experiments in a real environment measuring air pollutants such as: NH3, CH4, CO2, O2 along with the temperature, relative humidity and atmospheric pressure. Lastly, we experimentally evaluated and analyzed the two proposed schemes.