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IEEE 802.15. Wireless Personal Area Networks Wireless networks classified into four broad...
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Transcript of IEEE 802.15. Wireless Personal Area Networks Wireless networks classified into four broad...
IEEE 802.15
Wireless Personal Area Networks• Wireless networks classified into four broad categories:
– Wireless personal area network (WPAN): Hand-held and portable devices; slow to moderate transmission speeds.
– Wireless local area network (WLAN): i.e., IEEE 802.11a/b/g
– Wireless metropolitan area network (WMAN): Range up to 50 kilometers
– Wireless wide area network (WWAN): Connects networks in different geographical areas
Wireless Personal Area Networks (continued)
Wireless Personal Area Networks (continued)
Point-to-point transmission
Wireless Personal Area Networks (continued)
Point-to-multipoint transmission
Wireless Personal Area Networks
• WPANs encompass technology designed for portable devices– PDAs, cell phones, tablet or laptop computers– Low transmission speeds
• Three main categories:– IEEE 802.15 standards– Radio frequency ID (RFID)– IrDA
WPANs: IEEE 802.15.1 (Bluetooth)
• Bluetooth uses short-range RF transmissions– Users can connect wirelessly to wide range of computing
and telecommunications devices– Rapid and ad hoc connections between devices
• 802.15.1 adapted and expanded from Bluetooth– Designed for area of about 10 meters– Rate of transmission below 1 Mbps
• Two types of 802.15.1 network topologies– Piconet– Scatternet
WPANs: IEEE 802.15.1 (continued)
• Piconet: When two 802.15.1 devices come within range, automatically connect– Master: Controls wireless traffic– Slave: Takes commands from master– Piconet has one master and at least one slave
• Active slave: Connected to piconet and sending transmissions
• Parked slave: Connected but not actively participating
WPANs: IEEE 802.15.1 (continued)
Piconet
WPANs: IEEE 802.15.1 (continued)
• Devices in piconet can be in one of five modes:– Standby: Waiting to join a piconet– Inquire: Device looking for devices to connect to– Page: Master device asking to connect to specific slave– Connected: Active slave or master – Park/Hold: Part of piconet but in low-power state
• Scatternet: Group of piconets in which connections exist between different piconets
• 802.15.1 uses FHSS
WPANs: IEEE 802.15.1 (continued)
Scatternet
WPANs: IEEE 802.15.3
• Created in response to limitations of 802.15.1– High-rate WPANs
• Two main applications:– Video and audio distribution for home entertainment
systems• High-speed digital video transfer • Home theater• PC to LCD projector• Interactive video gaming
– High speed data transfer
WPANs: IEEE 802.15.3 (continued)
• Differences between 802.15.3 and 802.15.1– Quality of Service (QoS)– Security– High data rates– Spectrum utilization
IEEE 802.15.3 security modes
WPANs: IEEE 802.15.3 (continued)
• 802.15.3a: Will support data transfers up to 110 Mbps between max of 245 devices at 10 meters– Ultrawideband (UWB)– Intended to compete with USB 2.0 and FireWire
• IEEE 802.15.3b task group working on improving implementation and interoperability of 802.15.3
• IEEE 802.15.3c task group developing alternative physical layer standard that could increase speeds up to 2 Gbps
WPANs: IEEE 802.15.4
• Sometimes preferable to have low-speed, low-power wireless devices– Size can be dramatically reduced
• IEEE 802.15.4 standard addresses requirements for RF transmissions requiring low power consumption and cost
IEEE 802.15.4 data rates and frequencies
WPANs: IEEE 802.15.4 (continued)
• ZigBee Alliance: Industry consortium that promotes 802.15.4 standard
ZigBee and IEEE 802.15.4
WPANs: Radio Frequency ID (RFID)
RFID tag
WPANs: Radio Frequency ID (continued)
• Passive RFID tags: No power supply– Can be very small– Limited amount of information transmitted
• Active RFID tags: Must have power source– Longer ranges/larger memories than passive tags
RFID tags
WPANs: IrDA
• Infrared Data Association• IrDA specifications include standards for physical
devices and network protocols they use to communicate
• Devices communicate using infrared light-emitting diodes– Recessed into device– Many design considerations affect IrDA performance
WPANs: IrDA (continued)
• IrDA drawbacks:– Designed to work like standard serial port on a personal
computer, which is seldom used today– Cannot send and receive simultaneously– Strong ambient light can negatively impact transmissions– Angle and distance limitation between communicating
devices