Energy Savings via Harnessing Partial Packets in Body Area Networks

This work considers the incorporation, implications and potential energy savings of partial packet recovery schemes in Body Area Networks (BANs). Received packets which have not been fully corrected by the physical layer, called partial, are discarded by the vast majority of BAN protocols, as opposed to valid packets, which satisfy the error detection check and are propagated to higher layers. In typical networks using ARQ protocols, dropping partial packets results in retransmissions. However, because these packets contain useful information, partial packet recovery schemes have been proposed with demonstrated throughput and reliability benefits, targeting mostly wireless LANs. In order to quantify the potential energy benefits of harnessing partial packets in BANs, we use an experimental setup with four sensors mounted on a human body, transmitting information to a receiving node in a typical office environment. By precisely modeling the state transitions and energy consumption of sensors, we compare the efficiency of a baseline ARQ protocol against a scheme which leverages information in partial packets. Our results indicate that exploiting partial packets reduces on average the energy consumption of our sensors by 8--20%. The energy savings are pronounced in challenged channel conditions of high PER, where they can be up to 50%

Embracing corruption burstiness: Fast error recovery for ZigBee under wi-Fi interference

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.The ZigBee communication can be easily and severely interfered by Wi-Fi traffic. Error recovery, as an important means for ZigBee to survive Wi-Fi interference, has been extensively studied in recent years. The existing works add upfront redundancy to in-packet blocks for recovering a certain number of random corruptions. Therefore the bursty nature of ZigBee in-packet corruptions under Wi-Fi interference is often considered harmful, since some blocks are full of errors which cannot be recovered and some blocks have no errors but still requiring redundancy. As a result, they often use interleaving to reshape the bursty errors, before applying complex FEC codes to recover the re-shaped random distributed errors. In this paper, we take a different view that burstiness may be helpful. With burstiness, the in-packet corruptions are often consecutive and the requirement for error recovery is reduced as ”recovering any k consecutive errors” instead of ”recovering any random k errors”. This lowered requirement allows us to design far more efficient code than the existing FEC codes. Motivated by this implication, we exploit the corruption burstiness to design a simple yet effective error recovery code using XOR operations (called ZiXOR). ZiXOR uses XOR code and the delay is significantly reduced. More, ZiXOR uses RSSI-hinted approach to detect in packet corruptions without CRC, incurring almost no extra transmission overhead. The testbed evaluation results show that ZiXOR outperforms the state-of-the-art works in terms of the throughput (by 47%) and latency (by 22%)This work was supported by the National Natural Science Foundation of China (No. 61602095 and No. 61472360), the Fundamental Research Funds for the Central Universities (No. ZYGX2016KYQD098 and No. 2016FZA5010), National Key Technology R&D Program (Grant No. 2014BAK15B02), CCFIntel Young Faculty Researcher Program, CCF-Tencent Open Research Fund, China Ministry of Education—China Mobile Joint Project under Grant No. MCM20150401 and the EU FP7 CLIMBER project under Grant Agreement No. PIRSES-GA- 2012-318939. Wei Dong is the corresponding author

A Survey on WSN and MCN Convergence Networks, Journal of Telecommunications and Information Technology, 2020, nr 1

In this paper, we present a survey concerned with research focusing on the convergence of wireless sensor networks (WSN) and mobile cellular networks (MCN). The convergence of WSNs and MCNs may be a trigger stimulating new research dealing with such issues as architecture, protocols and air interfaces. The highlights and constraints of the phenomenon are discussed in this paper as well. The survey deals with convergence networks and with their smarty city applications. A few open research issues are also brought to the attention of researchers specializing in this fiel

Energy-aware network coding circuit and system design

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 73-78).Network Coding (NC) has been shown to provide several advantages in communication networks in terms of throughput, data robustness and security. However, its applicability to networks with resource constrained nodes, like Body Area Networks (BANs), has been questioned due to its complexity requirements. Proposed NC implementations are based on high-end CPUs and GPUs, consuming hundreds of Watts, without providing enough insight about its energy requirements. As more and more mobile devices, sensors and other low power systems are used in modern communication protocols, a highly efficient and optimized implementation of NC is required. In this work, an effort is made to bridge NC theory with ultra low power applications. For this reason, an energy-scalable, low power accelerator is designed in order to explore the minimum energy requirements of NC. Based on post-layout simulation results using a TSMC 65nm process, the proposed encoder consumes 22.15 uW at 0.4V, achieving a processing throughput of 80 MB/s. These numbers reveal that NC can indeed be incorporated into resource constrained networks with battery-operated or even energy scavenging nodes. Apart from the hardware design, a new partial packet recovery mechanism based on NC, called PPRNC, is proposed. PPRNC exploits information contained in partial packets, similarly to existing Hybrid-ARQ schemes, but with a PHY-agnostic approach. Minimization of the number of retransmitted packets saves transmission energy and results in higher total network throughput, making PPRNC an attractive candidate for energy constrained networks, such as BANs, as well as modern, high-speed wireless mesh networks. The proposed mechanism is analyzed and implemented using commercial development boards, validating its ability to extract information contained from partial packets.by Georgios Angelopoulos.S.M

Secure and efficient data extraction for ubiquitous computing applications

Ubiquitous computing creates a world where computers have blended seamlessly into our physical environment. In this world, a computer is no longer a monitor-and-keyboard setup, but everyday objects such as our clothing and furniture. Unlike current computer systems, most ubiquitous computing systems are built using small, embedded devices with limited computational, storage and communication abilities. A common requirement for many ubiquitous computing applications is to utilize the data from these small devices to perform more complex tasks. For critical applications such as healthcare or medical related applications, there is a need to ensure that only authorized users have timely access to the data found in the small device. In this dissertation, we study the problem of how to securely and efficiently extract data from small devices.;Our research considers two categories of small devices that are commonly used in ubiquitous computing, battery powered sensors and battery free RFID tags. Sensors are more powerful devices equipped with storage and sensing capabilities that are limited by battery power, whereas tags are less powerful devices with limited functionalities, but have the advantage of being operable without battery power. We also consider two types of data access patterns, local and remote access. In local data access, the application will query the tag or the sensor directly for the data, while in remote access, the data is already aggregated at a remote location and the application will query the remote location for the necessary information, The difference between local and remote access is that in local access, the tag or sensor only needs to authenticate the application before releasing the data, but in remote access, the small device may have to perform additional processing to ensure that the data remains secure after being collected. In this dissertation, we present secure and efficient local data access solutions for a single RFID tag, multiple RFID tags, and a single sensor, and remote data access solutions for both RFID tag and sensor

Practical packet combining for use with cooperative and non-cooperative ARQ schemes in wireless sensor networks

Although it is envisaged that advances in technology will follow a "Moores Law" trend for many years to come, one of the aims of Wireless Sensor Networks (WSNs) is to reduce the size of the nodes as much as possible. The issue of limited resources on current devices may therefore not improve much with future designs as a result. There is a pressing need, therefore, for simple, efficient protocols and algorithms that can maximise the use of available resources in an energy efficient manner. In this thesis an improved packet combining scheme useful on low power, resource-constrained sensor networks is developed. The algorithm is applicable in areas where currently only more complex combining approaches are used. These include cooperative communications and hybrid-ARQ schemes which have been shown to be of major benefit for wireless communications. Using the packet combining scheme developed in this thesis more than an 85% reduction in energy costs are possible over previous, similar approaches. Both simulated and practical experiments are developed in which the algorithm is shown to offer up to approximately 2.5 dB reduction in the required Signal-to-Noise ratio (SNR) for a particular Packet Error Rate (PER). This is a welcome result as complex schemes, such as maximal-ratio combining, are not implementable on many of the resource constrained devices under consideration. A motivational side study on the transitional region is also carried out in this thesis. This region has been shown to be somewhat of a problem for WSNs. It is characterised by variable packet reception rate caused by a combination of fading and manufacturing variances in the radio receivers. Experiments are carried out to determine whether or not a spread-spectrum architecture has any effect on the size of this region, as has been suggested in previous work. It is shown that, for the particular setup tested, the transitional region still has significant extent even when employing a spread-spectrum architecture. This result further motivates the need for the packet combining scheme developed as it is precisely in zones such as the transitional region that packet combining will be of most benefit

Synchronous Transmissions in Low-Power Wireless: A Survey of Communication Protocols and Network Services

Low-power wireless communication is a central building block of Cyber-physical Systems and the Internet of Things. Conventional low-power wireless protocols make avoiding packet collisions a cornerstone design choice. The concept of synchronous transmissions challenges this view. As collisions are not necessarily destructive, under specific circumstances, commodity low-power wireless radios are often able to receive useful information even in the presence of superimposed signals from different transmitters. We survey the growing number of protocols that exploit synchronous transmissions for higher robustness and efficiency as well as unprecedented functionality and versatility compared to conventional designs. The illustration of protocols based on synchronous transmissions is cast in a conceptional framework we establish, with the goal of highlighting differences and similarities among the proposed solutions. We conclude the paper with a discussion on open research questions in this field.Comment: Submitted to ACM Computing Survey

The SoftPHY Abstraction: from Packets to Symbols in Wireless Network Design

At ever-increasing rates, we are using wireless systems to communicatewith others and retrieve content of interest to us. Current wirelesstechnologies such as WiFi or Zigbee use forward error correction todrive bit error rates down when there are few interferingtransmissions. However, as more of us use wireless networks toretrieve increasingly rich content, interference increases inunpredictable ways. This results in errored bits, degradedthroughput, and eventually, an unusable network. We observe that thisis the result of higher layers working at the packet granularity,whereas they would benefit from a shift in perspective from wholepackets to individual symbols.From real-world experiments on a 31-node testbed of Zigbee andsoftware-defined radios, we find that often, not all of the bitsin corrupted packets share fate. Thus, today's wireless protocolsretransmit packets where only a small number of the constituent bitsin a packet are in error, wasting network resources. In thisdissertation, we will describe a physical layer that passesinformation about its confidence in each decoded symbol up to higherlayers. These SoftPHY hints have many applications, one ofwhich, more efficient link-layer retransmissions, we will describe indetail. PP-ARQ is a link-layer reliable retransmission protocolthat allows a receiver to compactly encode a request forretransmission of only the bits in a packet that are likely in error.Our experimental results show that PP-ARQ increases aggregate networkthroughput by a factor of approximately 2x under variousconditions. Finally, we will place our contributions in the contextof related work and discuss other uses of SoftPHY throughout thewireless networking stack