Property of the HomeRF Working Group Technical Overview This presentation is provided by the HomeRF Working Group. Direct questions or requests for softcopy to: [email protected], 503-291-2563 Or contact HomeRF Communications Chairman, Wayne Caswell ([email protected], 512-335-6073)
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Technical Overview
This presentation is provided by the HomeRF Working Group.Direct questions or requests for softcopy to:
[email protected], 503-291-2563Or contact HomeRF Communications Chairman, Wayne Caswell
HomeRF provides real-time media streaming to more nodes over a greater distance.
Dial-up / MP3 Audio
MPEG2 Video
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Attenuation: Signal Strength Diminishes through Materials
BU
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Wood and plaster Walls or Floors are OK. Even Brick.
Metal and thick rock block the RF signals.
The Higher the Frequency, the more signal loss.
5 GHz is worse than 2.4 GHz.
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Multi-path in Homes: More Absorption, Less Reflection
Signals can arrive at different times and cancel each other out.
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Technical Overview Topics
• Toll-quality Voice & Streaming Media
• Data Throughput, Range & Attenuation
• Security & Interference Immunity
• Power Consumption & Form Factor
• Cost
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is Secure and Reliable
• Frequency Hopping Spread SpectrumFrequency Hopping Spread Spectrum– Invented for the US Military to avoid jamming,
denial of service, and eavesdropping
• Performance with InterferencePerformance with Interference– Microwave ovens, cordless phones,
baby monitors, video senders, neighbors– High Density Apartments
• Security LayersSecurity Layers• Application Layer Security Option• 128-bit Encryption Option • Standardized Teach/Learn• 24-bit Network ID• Random Frequency Hopping• Spread-Spectrum• Digital
BU
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3 non-overlapping channels.
is Secure and Reliable
BEWARE: RF signals can penetrate walls
Access from car or
hilltop ???
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Interference:HomeRF hops around it
FHSS DSSS
TimeTime
Fre
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cy
IEEE 802.11b waits for Interference to go away
2.4 GHz
2.5 GHz
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p Spectral / Temporal Characteristics of Microwave Ovens
Frequency
PowerSpectralDensity
Used ISM band (75 MHz)
Average Power Spectrum(10 to 30 MHz)
Next
hop
clear
Next
hop
clear
Next
hop
clear
Next
hop
clear
Next
hop
clear
Active Interference Avoidance
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10 ms
Active data traffic
Hop BeaconfN Data 1 Ak1
Active calls
Dn5 Up5
Normal calls continue
Dn5 Up5Dn2 Up2
Data packet succeeds on retry
Ak2Data 2Hop BeaconfN+1
Control point allocatesretry of up/down 2
Data 2 Dn2 Up2
Latency is bounded to 10 ms even in the presence of interference
Active Interference Avoidance
Interference 1contacts fN
Dn2 Up2
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IEEE 802.11b
802.11b – DSSS using channel 3 (static frequency)
Source: Celerity Digital Broadband Test
2.4 2.5 GHz
Signal Strength
2.40 GHz
2.50 GHz
0 250 500 s
2.45 GHz
Frequency over Time
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Bluetooth™
Bluetooth Headset signal31.25 µs between pulse pairs125 µs between pulse sets
Source: Celerity Digital Broadband Test
2.4 2.5 GHz
Signal Strength
2.40 GHz
2.50 GHz
0 250 500 s
2.45 GHz
Frequency over Time
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2.4 GHz Cordless Phone
Multiple Channel Cordless TelephoneTransmit Receive on separate channelsChannel selection is arbitrary
Source: Celerity Digital Broadband Test
2.4 2.5 GHz
Signal Strength
2.40 GHz
2.50 GHz
0 250 500 s
2.45 GHz
Frequency over Time
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Coexistence within ISM band
WLAN 802.11bBluetooth™Cordless Telephone
Source: Celerity Digital Broadband Test
2.4 2.5 GHz
Signal Strength
2.40 GHz
2.50 GHz
0 250 500 s
2.45 GHz
Frequency over Time
802.11b politely waits for interference to go away – potentially a very long time with cordless phones.
Bluetooth interference, at 1600 hops/sec can also be severe.
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Technical Overview Topics
• Toll-quality Voice & Streaming Media
• Data Throughput, Range & Attenuation
• Security & Interference Immunity
• Power Consumption & Form Factor
• Cost
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p • Smallest WLAN form factor• 1.6 Mbps and full home coverage• < 10mW standby power draw• Full TCP/IP connectivity• Ideal for handheld Internet appliances,
personal imaging and audio devices
Specifications:Physical• Type II size, < 20 grams• 0 – 40 degree C operation• CE, EMC-EEC 89/336 CompliantElectrical• 3.3 V, 120mA Rc; 250mA Tx modes• 3mA standby mode
Simple Design: enables small form factor for embedded apps
Up
dat
e fo
r 2.
0?
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Hand Held Trends
• Larger, higher resolution Displays with more Colors
• More Performance, Less Cost
– e.g. Video streaming
• Better Text rendering
• Wireless (WAN, WLAN, PAN)
• PDA becomes Phone, MP3…
• Phone becomes PDA, MP3…
• Digital Imaging
• PocketPC gains some ground – Palm still has >70% share
With Microsoft ClearType, palm-sized devices can act as eBooks.
• Ideal for the Broadband (voice, data, entertainment)– Blends several technologies to enable Digital Convergence– Broadband data at Ethernet speeds “plus” toll-quality voice
and streaming media
• Designed and optimized for Households & SOHO:– Simplicity, Security/Privacy, Interference, Cost, Applications
• Smooth roadmap to 20 Mb/s and beyond – Multi-band support for 2.4 GHz and 5 GHz (802.11a)
• More information at www.HomeRF.org– Learning Center for W.Papers, Presentations, etc.