Network Kernel Architectures and Implementation (01204423) ) Medium Access Control and WPAN Technologies Chaiporn Jaikaeo [email protected]Department of Computer Engineering Kasetsart University Materials taken from lecture slides by Karl and Willig
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Wireless Embedded Systems (0120442x) Medium Access Control
Wireless Embedded Systems (0120442x) Medium Access Control. Chaiporn Jaikaeo [email protected] Department of Computer Engineering Kasetsart University. Materials taken from lecture slides by Karl and Willig. Overview. Principal options and difficulties Contention-based protocols - PowerPoint PPT Presentation
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Overview Principal options and difficulties Contention-based protocols Schedule-based protocols Wireless Personal Area Networks
Technologies
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IEEE 802.15.4 IEEE standard for low-rate WPAN (LR-WPAN)
applications Low-to-medium bit rates Moderate delays without too strict requirements Low energy consumption
Physical layer 20 kbps over 1 channel @ 868-868.6 MHz 40 kbps over 10 channels @ 905 – 928 MHz 250 kbps over 16 channels @ 2.4 GHz
MAC protocol Single channel at any one time Combines contention-based and schedule-based
schemes Asymmetric: nodes can assume different roles
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868MHz / 915MHz PHY
2.4 GHz
868.3 MHz
Channel 0 Channels 1-10
Channels 11-26
2.4835 GHz
928 MHz902 MHz
5 MHz
2 MHz
2.4 GHz PHY
802.15.4 PHY Overview Operating frequency bands
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802.15.4 Device Classes Full function device (FFD)
Any topology Network coordinator capable Talks to any other device
Reduced function device (RFD) Limited to star topology Cannot become a network coordinator Talks only to a network coordinator Very simple implementation
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802.15.4 Network Topologies
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802.15.4 Beaconed Mode Superframe structure
GTS assigned to devices upon request
Active period Inactive period
Contention access period
Guaranteed time slots (GTS)
Beacon
802.15.4 GTS Data Transfer Device coordinator
If having allocated GTS, wake up and send
Otherwise, send during CAP Using slotted CSMA
Coordinator device If having allocated GTS,
wake up and receive Otherwise, see picture
Coordinator Device
Beacon
Data request
Acknowledgement
Data
Acknowledgement
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IEEE 802.15.4 Adopters ZigBee
Requires battery life of at least two years be certified
Applications: Industrial control, embedded sensing, home automation
ZigBee RF4CE (Radio Frequency for Consumer Electronics)
Nest (acquired by Google) Learning thermostats,
Smoke and CO alarms WiFi- and ZigBee-enabledhttps://nest.com
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Bluetooth Smart Formally Bluetooth Low Energy (BLE)
Part of Bluetooth 4.0 Specification Based on Nokia's Wibree technology First smartphones to support