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