design and synthesis of embedded systems virk [email protected] kashif virk office 322.222 informatics...
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Design and Synthesisof Embedded Systems
http://www.imm.dtu.dk/[email protected]
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.