design and synthesis of embedded systems virk virk@imm.dtu.dk kashif virk office 322.222 informatics...

Design and Synthesisof Embedded Systems

http://www.imm.dtu.dk/~virkvirk@imm.dtu.dk

Kashif VirkOffice 322.222

Informatics and Mathematical ModellingTechnical University of Denmark

Richard Petersens Plads, Building 321DK2800 Lyngby, Denmark

02202 Lecture 2 - Embedded Systems 2

Energy & Performance Considerations for Smart Dust

Smart Dust Mote

02202 Lecture 2 - Embedded Systems 3

Energy & Performance Considerations for Smart Dust

Energy Sources

1. Lithium Energy Cell

2. Thin-Film Vanadium Oxide + Molybdenum Oxide

3. Ultra Capacitor

4. Solar Cell

5. Low Energy Vibration

6. More Exotic Solutions ranging from radioactive materials to bio-chemical ones.

02202 Lecture 2 - Embedded Systems 4

Energy & Performance Considerations for Smart Dust

Component Sources of Power Consumption

Static Power – Leakage Current

Dynamic Power – Switching (Charging + Power Supply Short Circuiting) Current

02202 Lecture 2 - Embedded Systems 5

Energy & Performance Considerations for Smart Dust

Energy Consumption in the Computing Subsystem

Embedded Microprocessor

Random Logic

Ripple-Carry Adders

Accumulators

Registers & Register Banks

Static RAM

Buses

Instruction Set

02202 Lecture 2 - Embedded Systems 6

Energy & Performance Considerations for Smart Dust

Energy Consumption in the Sensing Subsystem

•Transducers

•Pre Amplifiers / Low Noise Amplifiers

•A/D Converters

02202 Lecture 2 - Embedded Systems 7

Energy & Performance Considerations for Smart Dust

Energy Consumption in the Communication Subsystem

RF Communication Block

Optical Communication Block

LN

A

FREQUENCYSYNTHESIZER

90 0

BANDPASSFILTER

VG

A+ DSPA/DCONVERTER

PN CODEGENERATOR

02202 Lecture 2 - Embedded Systems 8

Energy & Performance Considerations for Smart Dust

Anticipated Applications

Building Environment Monitoring

Earthquake Forecast

Vehicle Tracking

02202 Lecture 2 - Embedded Systems 9

Energy & Performance Considerations for Smart Dust

Ad Hoc NetworksAd hoc [Latin: For this (purpose only)] networks are not (necessarily) connected to any static infrastructure (like a cellular base station or a wired network). In ad hoc networks, the nodes are a part of the network only for the duration of a communications session or, in the case of mobile or portable devices, while in some close proximity to the rest of the network. They can be set up anywhere without any need for external static infrastructure [1]. Ad hoc networks consisting of mobile nodes are called Mobile Ad hoc NETworks (MANETs). Sensor Networks have many features similar to MANETs and are sometimes called Hybrid Ad hoc Networks.

Peer-to-Peer NetworksP2P networks are a class of ad hoc networks in which an overlay network is built on top of a physical network infrastructure with minimal or no central coordination. P2P networks are characterized by a group of nodes with the same type of interests connected over the same communication system. A P2P network is self-organized and self-administrative as the nodes discover their peers autonomously, and self-reconfiguring as the nodes seek new peers automatically as their current peers are temporarily or permanently disconnected from the network. Each peer has both a client and a server role [2].

02202 Lecture 2 - Embedded Systems 10

Design Considerations

Typical Design Considerations for Sensor Networks

Ad Hoc Deployment

– Un-Attended Operation

Un-Attended Operation

– Energy Scavenging (instead of occasional battery replacement at far off places)

– Self Organization (Autonomous Operation)

Self Organization

– Neighbor Discovery

– Topology Formation

02202 Lecture 2 - Embedded Systems 11

Typical Design Considerations for Sensor Networks ... contd.

Self Reconfiguration

– Due to network dynamics (node failures, node mobility, low connectivity)

Scalability

– Up (due to more nodes joining a network)

– Down (due to low connectivity, node failures, mobile nodes)

Mobility

– Mobile Node (e.g., ZebraNet, Twister - Movie)

– Mobile Phenomenon (e.g., Great Duck Island)

– Mobile Observer (e.g., Environment Monitoring for Toxic Emissions)

– Hybrid

Design Considerations

02202 Lecture 2 - Embedded Systems 13

Design Considerations

Typical Design Considerations for Sensor Networks ... contd.

Location-based Addressing

–Triangulation-based Localization

– Multilateration-based Localization

Network Architecture

– Hierarchical/Tiered Network

– Flat Network

02202 Lecture 2 - Embedded Systems 14

Design Considerations

Typical Design Considerations for Sensor Networks ... contd.

Resource Constraints

– Energy (Duty Cycled Electronics, Power-Aware Algorithms)

– Processing Constraints (Collaborative Signal Processing)

– Storage Constraints (Data Aggregation – Data Fusion – Beamforming)

– Bandwidth Constraints (In-Network Processing)

Power-Aware Algorithms

– Power-Aware MAC Protocols (TDMA, CSMA, Hybrid)

– Power-Aware Routing Protocols (LEACH, Directed Diffusion, Clustering)

02202 Lecture 2 - Embedded Systems 15

Design Considerations

How do we design these embedded systems?

Sensor Node Platform (Hardware)

Operating System (Task Scheduling, Dynamic Power

Management, Task Assignment, Task Mapping, Load

Balancing, etc.) & Networking Protocols (System

Software)

Programming Models & Languages

Virtual Machine

Middleware

Applications (Application Software)

Design Methodologies

02202 Lecture 2 - Embedded Systems 16

Power-Aware Design of Embedded Systems

Power-Aware vs. Low-Power Operation

Power-Aware Operation results in Graceful Performance/Quality of Service (QoS) Degradation

Low-Power Operation results in All-or-None Performance

02202 Lecture 2 - Embedded Systems 17

References

[1] Ad Hoc in Wireless Local Area Networks (WLAN) by Jani Kaartinen (Control Engineering Laboratory, Helsinki University of Technology, Helsinki, Finland)

[2] A Local Search Mechanism for Peer-to-Peer Networks by Vana Kalogeraki (Hewlett-Packard Labs, Palo Alto California, USA), Dimitrios Gunopulos (University of California Riverside, California, USA), and D. Zeinalipour-Yazti (University of California Riverside, California, USA), CIKM’02, November, 2002.