High Rate Wireless Personal Area Networks

Wireless Communications
Chapter 6
High Rate Wireless Personal Area
Networks
Wireless# Guide to Wireless Communications 2
Objectives
•
Define a high rate wireless personal area network (HR
WPAN)
•
List the different HR WPAN standards and their
applications
•
Explain how WiMedia and UWB work
•
Outline the issues facing WPAN technologies
•
Describe the security features of each HR WPAN
technology
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High Rate WPAN Standards
•
IEEE is currently working on two standards
–
IEEE 802.15.3 and 802.15.5
•
IEEE 802.15.3 standard
–
Defines the specifications for HR WPANs supporting
speeds of 11, 22, 33, and up to 55 Mbps
•

In the 2.4 GHz ISM band
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802.15.3 High Rate WPANs
•
IEEE standard defines the MAC and PHY layers
•
WiMedia Alliance
–
Formed to support the development of any necessary
higher-layer protocols
•
And software specifications for 802.15.3
•
Potential applications
–
Connecting digital cameras to printers and kiosks
–
Connecting laptops to multimedia projectors and sound
systems
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802.15.3 High Rate WPANs
(continued)
•
Application characteristics
–
Require high throughput
–
Transceiver should be low-power
–
Cost should be low

–
Require quality-of-service (QOS) capabilities
–
Connections should be simple and automatic
–
Devices should be able to connect to multiple other
devices
–
Security features should be included
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WiMedia Protocol Stack
•
WiMedia group defined two different architectures
–
For the upper layers of the protocol stack
–
One is used for multimedia audio/visual applications
and the other for data transfer applications
•
The lower two layers of the stack (MAC and PHY)
–
Are implemented in hardware
•
802.15.3 PHY layer
–
Converts data bits into a modulated RF signal
–
802.15.3 standard uses the ISM 2.4 GHz band
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WiMedia Protocol Stack (continued)

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WiMedia Protocol Stack (continued)
•
802.15.3 PHY layer (continued)
–
Supports two different channel plans
•
A coexistence channel plan
•
A high-density channel plan
–
Channels are limited to 15 MHz bandwidth
–
IEEE 802.15.3 standard specifies five data rates
•
11 Mbps, 22 Mbps, 33 Mbps, 44 Mbps, and 55 Mbps
–
Trellis code modulation (TCM)
•
Encodes the digital signal so single bit errors can be
detected and corrected
–
Also called error correction (FEC)
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WiMedia Protocol Stack (continued)
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WiMedia Protocol Stack (continued)
•
Modulation
–

See Table 6-2 for modulation techniques
–
Enhancements
•
Passive scanning
•
Dynamic channel selection
•
Ability to request channel quality information
•
Link quality and received signal strength indication
•
Transmit power control
•
An 802.11 coexistence channel plan
•
Lower transmit power
•
Neighbor piconet capability
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WiMedia Protocol Stack (continued)
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802.15.3 Network Topology
•
Piconet coordinator (PNC)
–
Role assumed by the first device in the area
–
Provides all of the basic communications timing in a
piconet

–
PNC sends a beacon
•
The piconet is peer-to-peer
–
Devices can transmit data directly to each other
•
The PNC is also responsible for managing QoS
•
Devices can form a dependent piconet
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802.15.3 Network Topology (continued)
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802.15.3 Network Topology (continued)
•
Types of dependent piconets
–
Child piconets
•
Useful for extending the coverage of a piconet
–
Neighbor piconets
•
Allow coexistence with other piconets in the same area
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802.15.3 Network Topology (continued)
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802.15.3 Network Topology (continued)
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Additional MAC Layer Functionality

•
The IEEE 802.15.3 MAC layer functionality
–
Connection time (association) is fast
–
Devices associated with the piconet can use a short,
one-octet device ID
–
Devices can obtain information about the capabilities of
other devices
–
Peer-to-peer (ad hoc) networking
–
Data transport with QoS
–
Security
–
Efficient data transfer using superframes
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Additional MAC Layer Functionality
(continued)