Appearing in 1st IEEE International Workshop on Sensor Net Protocols and Applications (SNPA). Anchorage, Alaska, USA. May 11, 2003. RMST: Reliable Data Transport in Sensor Networks Fred Stann, John Heidemann Abstract – Reliable data transport in wireless sensor networks is a multifaceted problem influenced by the physical, MAC, network, and transport layers. Because sensor networks are subject to strict resource constraints and are deployed by single organizations, they encourage revisiting traditional layering and are less bound by standardized placement of services such as reliability. This paper presents analysis and experiments resulting in specific recommendations for implementing reliable data transport in sensor nets. To explore reliability at the transport layer, we present RMST (Reliable Multi- Segment Transport), a new transport layer for Directed Diffusion. RMST provides guaranteed delivery and fragmentation/reassembly for applications that require them. RMST is a selective NACK-based protocol that can be configured for in-network caching and repair. Second, these energy constraints, plus relatively low wireless bandwidths, make in-network processing both feasible and desirable [3]. Third, because nodes in sensor networks are usually collaborating towards a common task, rather than representing independent users, optimization of the shared network focuses on throughput rather than fairness. Finally, because sensor networks are often deployed by a single organization with inexpensive hardware, there is less need for interoperability with existing standards. For all of these reasons, sensor networks provide an environment that encourages rethinking the structure of traditional communications protocols. The main contribution is an evaluation of the placement of reliability for data transport at different levels of the protocol stack. We consider implementing reliability in the MAC, transport layer, application, and combinations of these. We conclude that reliability is important at the MAC layer and the transport layer. MAC-level reliability is important not just to provide hop-by-hop error recovery for the transport layer, but also because it is needed for route discovery and maintenance. (This conclusion differs from previous studies in reliability for sensor nets that did not simulate routing. [4]) Second, we have developed RMST (Reliable Multi-Segment Transport), a new transport layer, in order to understand the role of in- network processing for reliable data transfer. RMST benefits from diffusion routing, adding minimal additional control traffic. RMST guarantees delivery, even when multiple hops exhibit very high error rates. 1 Introduction Wireless sensor networks provide an economical, fully distributed, sensing and computing solution for environments where conventional networks are impractical. This paper explores the design decisions related to providing reliable data transport in sensor nets. The reliable data transport problem in sensor nets is multi-faceted. The emphasis on energy conservation in sensor nets implies that poor paths should not be artificially bolstered via mechanisms such as MAC layer ARQ during route discovery and path selection [1]. Path maintenance, on the other hand, benefits from well- engineered recovery either at the MAC layer or the transport layer, or both. Recovery should not be costly however, since many applications in sensor nets are impervious to occasional packet loss, relying on the regular delivery of coarse-grained event descriptions. Other applications require loss detection and repair. These aspects of reliable data transport include the provision of guaranteed delivery and fragmentation/ reassembly of data entities larger than the network MTU. Sensor networks have different constraints than traditional wired nets. First, energy constraints are paramount in sensor networks since nodes can often not be recharged, so any wasted energy shortens their useful lifetime [2]. This work was supported by DARPA under grant DABT63-99-1-0011 as part of the SCAADS project, and was also made possible in part due to support from Intel Corporation and Xerox Corporation. Fred Stann and John Heidemann are with USC/Information Sciences Institute, 4676 Admiralty Way, Marina Del Rey, CA, USA E-mail: fstann@usc.edu, johnh@isi.edu. 2 Architectural Choices There are a number of key areas to consider when engineering reliability for sensor nets. Many current sensor networks exhibit high loss rates compared to wired networks (2% to 30% to immediate neighbors)[1,5,6]. While error detection and correction at the physical layer are important, approaches at the MAC layer and higher adapt well to the very wide range of loss rates seen in sensor networks and are the focus of this paper. MAC layer protocols can ameliorate PHY layer unreliability, and transport layers can guarantee delivery. An important question for this paper is the trade off between implementation of reliability at the MAC layer (i.e. hop to hop) vs. the Transport layer, which has traditionally been concerned with end-to-end reliability. Because sensor net applications are distributed, we also considered implementing reliability at the application layer. Our goal is to minimize the cost of repair in terms of transmission.

RMST: Reliable Data Transport in Sensor Networks

https://orca.cf.ac.uk/88855/1/Metering_final-version.pdf

Building energy metering and environmental monitoring – A state-of-the-art review and directions for future research

Power-line communications (PLC) have proven to be susceptible to the next-generation power transmission/distribution systems with end-to-end communication capability, considered as a revolutionary and evolutionary regime of existing power grids More importantly, with recent advancements in PLC technological regulation, standardization and certification have spurred a lot of interest in the field of advanced communication and control technologies for heterogeneous networks These advancements are expected to greatly enhance efficiency and reliability of future power systems with renewable energy resources, as well as distributed intelligence and demand response (DR) programs As various national and international organizations have started to draw PLC regulations, standards and technologies for countries, these standards intend to determine important criteria such as bandwidth, modulation types, channel coding schemes, operating frequency and electromagnetic capability limits from fixed indoor/outdoor applications to smart grid (SG) applications Depending on the worldwide PLC regulation, standardization and technological developments, security schemes built around them can become interoperable from a standard point of view, but still have incompatible configurations or different maturity levels, or include non-standardized PLC functions Moreover, the PLC based systems/solutions for renewable energy integration, are also surveyed in terms of distributed-power system (DPS) and distributed energy resources (DERs) units monitoring/controlling and management purposes Thus, a particular section is dedicated to PLC based systems/solutions utilization of renewable energy sources (RESs) in SG covering all aspects of a monotype and hybrid energy plants Finally, the survey is carried on by reviewing the most recent and comprehensive articles to highlight the importance of PLC in a logical way in the smart grid for readers

Power-line communications for smart grid: Progress, challenges, opportunities and status

A ZigBee-based monitoring and protection system for building electrical safety

Intelligent homes’ technologies to optimize the energy performance for the net zero energy home

To achieve better sound quality and to improve data reception, digital radio mondiale (DRM) offers a worldwide initiative to bring analog amplitude modulation (AM) radio into the digital era. DRM systems use coded orthogonal frequency division multiplexing (COFDM) modulation with a multilevel coding scheme to get high resistance to the multipath padding and interference. The bandwidth of a DRM passband signal is less than 20 kHz and the number of carriers used in orthogonal frequency division multiplexing (OFDM) modulation is relatively small. For this reason, DRM systems use non-power-of-two Fast Fourier Transforms (FFT) for OFDM demodulation, such processing gives way to more speed and power consumption in critical paths in DRM receivers. In this paper, we propose a mixed radix-2n and prime factor FFT algorithm for portable DRM receivers. Using the proposed architecture, we can reduce the processing time and energy consumption compared to conventional digital signal processor (DSP) based DRM receivers.

Design of a mixed prime factor FFT for portable digital radio mondiale receiver

Power line communications provide a convenient and cost-effective solution for data transmission, because power mains are the most popular and widely distributed medium in the world However, the time-variant and unpredictable channel environment for communication poses a major challenge In this regard, we propose a robust power line modem based on adaptively signal detection techniques for networked home appliances The modulation scheme used in this research is a chirped spread spectrum with a separate matched filter based on an adaptive threshold decision technique In addition, we propose an adaptive retransmission technique based on flexible carrier frequency selection using a ram based look-up table (LUT) for improving carrier sense multiple access with collision avoidance (CSMA/CA) media access protocol The proposed power line transceiver is realized in 035 mum CMOS technology and verified with networked various consumer electronic devices The results show that the proposed power line communication modem is well qualified as a communication device for home automation 

A Power Line Communication Modem Based on Adaptively Received Signal Detection for Networked Home Appliances

This paper propose the design of PHY simulator for WBAN system in IEEE 802.15.6. Recently, WBAN system is most popular system in wireless communication. According to the technical requirement of the WBAN task group, many companies and research institutes have proposed physical layer architectures to provide fundamental technologies for the WBAN communication systems. Since there are various service scenarios for in-body or on-body applications, the physical layer proposals include UWB as well as narrowband techniques. The implemented WBAN PHY simulator (in this paper) is designed fixed point that is specified PPDU structure and modulation method in WBAN TG6. In the WBAN PHY case, the modulations method is changed by frequency band and data rate. After implementation of simulator, we are going to design WBAN for hardware implementation. We are supposed to implement architecture of a chip that has mixed mode, PSK and FSK in MICS baseband for WBAN. WBAN simulator is designed by using MATLAB.

Narrowband Physical Layer Design for WBAN System

This paper proposes the design and VLSI implement of high efficient Context-based Adaptive Variable Length Coding (CAVLC) encoder which adopted a modified Variable Length Coding (VLC) look up table technique and parallel processing. The proposed CAVLC encoder used upper and under buffer as input buffer to perform zigzag scanning with both way ordering. Because of this, the proposed CAVLC encoder can be read and write concurrently. Moreover, we design the CAVLC encoder procedure with parallel processing which uses two generators for information signals and control signals to operate CAVLC modules such as a coeff_token (TotalCeff and TrailingOnes) module, a level module, a total_zeros module, and a run_before module. The proposed CAVLC is prototyped in Verilog-HDL, implemented and synthesized with megnachip 0.18 µm CMOS tech. The synthesis result shows that the gate count is about 12K with the clock constraint of 140Mhz. The proposed CAVLC encoder is suitable for real-time video applications.

Implementation of High Efficient CAVLC Encoder for H.264/AVC

This paper presents a novel low-cost high-performance CAVLC decoder for H.264/AVC. The proposed CAVLC decoder generates the length of coeff_token and total_zeros symbols with simple arithmetic operation. So, it can be implemented with reduced look-up table. And we propose multi-symbol run_before decoder which has enhanced throughput. It can decode more than 2.5 symbols in a cycle if there are run_before symbols to be decoded. The hardware cost is about 12K gates when synthesized at 125MHz.

Kyu-Yeul Wang

Papers

Design of a mixed prime factor FFT for portable digital radio mondiale receiver

A Power Line Communication Modem Based on Adaptively Received Signal Detection for Networked Home Appliances

Narrowband Physical Layer Design for WBAN System

Implementation of High Efficient CAVLC Encoder for H.264/AVC

A Novel Low-Cost High-Throughput CAVLC Decoder for H.264/AVC