EECS 373 Design of Microprocessor-Based Systems Mark Alitawi Sarah Spitzer Kaiyu Yan University of...
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Transcript of EECS 373 Design of Microprocessor-Based Systems Mark Alitawi Sarah Spitzer Kaiyu Yan University of...
EECS 373Design of Microprocessor-Based Systems
Mark Alitawi Sarah Spitzer Kaiyu YanUniversity of Michigan
RadiosNovember 27, 2012
• What are radioso How do they work?
• Fundamental characteristicso Design tradeoffs
• Common radio standards/protocolso Where characteristics fall under (above)
• Applicationso Choosing a specific type of radio
Outline
• A device that enables wireless transmission of signalso Electromagnetic wave o Transmitter sends signal to Receiver
What are Radios?
• Modulationo Properties of Fourier
transformso Analog/Digitalo Frequency vs Amplitude vs.
Phase, etc.
How Radios Work - Transmitting
• Envelope Detectiono Detect carrier freq.
• Filters
• Demodulation
How Radios Work - Receiving
• Antenna picks up modulated radio waves
• Tuner filters out specific frequency ranges
• Amplitude variations detected with demodulation
• Amplifier strengthens the clipped signal and sends it through the speaker
How Radios Work – Receiving (AM Radio Example)
• Why so many protocols?
• Types/Advantages/Disadvantageso Short vs. long distanceo high vs. low power/energyo high vs. low speeds
• Physical Constraintso Feasibility
Radio Characteristics
• Bluetooth
• Zigbee/802.15.4
• ANT
• WiFi
Common Radio Protocols
• Radio band: 2.4-2.48 GHz
• Average 1 Mbps - Up to 3 Mbps
• Supports point-to-point and point-to-multipointo Creates personal area networks (PANs/Piconets)o Connects up to 8 devices simultaneously
• Minimal interference between deviceso Devices alter frequencies arbitrarily after
packet exchanges -up to 1600 times/second - frequency hopping
• 3 classes of Bluetooth
Bluetooth
• Wireless communication between deviceso Mobile phones, laptops, cameras, gaming
controllers, computer peripherals, etc
• Short range sensor transmission
• Share multimedia - pictures, video, music
• A2DP - Advanced Audio Distribution Profileo Stream audio wirelessly
Bluetooth Applications
• Zigbee is built on top of 802.15.4
• Radio bands: 868MHz in Europe, 915MHz in US and Australia. 2.4GHz else worldwide.
• Low data-rate - 250 kbps, low power – Up to 1000 days
• Transmits over longer distances through mesh networks
Zigbee/802.15.4
• Wireless environmental sensorso Temperature, pressure, sound, luminous
intensity
• Medical deviceso Glucose meters, heart monitors
• Household automationo Security/temperature controllerso Smoke/motion detectors
Zigbee/802.15.4 Applications
• Radio band: 2.4GHz
• Periodic transfers of small amounts of sensor info between - burst messaging
• High efficiencyo Low overhead, minimal wakeup time
• Minimizes interference by using Direct-Sequence Spread Spectrum (DSSS).
• Limited to sensor applicationso Short range - Highly reliable up to 3mo Limited speed - 1 Mbpso Low power - Transceiver batteries last up to 3
years
ANT
• Sensors that are updated on the order of secondso Performance monitoring, medical, heart rateo Humidity, temperatureo Speed/distance traveled monitors
ANT Applications
• Dual Bands: 2.4GHz and 5GHz
• 802.11a/b/g/no Cost vs Speed vs Interference tradeoff
• Roaming
• Global standard
• High speedo Up to 300 Mbps
• High power consumption o Concern for mobile devices
• Rangeo Up to 100m
WiFi
WiFi – example (802.11g)
• Internet/Networkso Businesseso Schoolso Home
• Examples: Computers, phones, XBox, Airplay
WiFi Applications
Protocol Comparisons
Bluetooth Zigbee/802.15.4 ANT WiFi
Speed Moderate Low Moderate High
Range Moderate - High High Low High
Power Consumption
Low - Moderate Low Low High
Protocol Comparisons
Questions?
Comments?
Discussion?