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Technical Overview
This presentation is provided by the HomeRF Working Group.Direct questions or requests for softcopy to:
Info@homerf.org, 503-291-2563Or contact HomeRF Communications Chairman, Wayne Caswell
(wayne.caswell@icm.siemens.com, 512-335-6073)
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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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HomeRF Node Types
Laptop(A-node)
asynchronous
Cordless Handset(I-node)
isochronous
Internet Appliance(SA-node)
Audio Headset(S-node)streaming
Broadband Internet
Control Point(CP Class 1)
Wired network
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OSI 7-Layer Network Stack Model
7. Application
6. Presentation
5. Session
4. Transport
3. Network
2. Data Link (MAC)
1. Physical (PHY)
HomeRF Specification uses, references, or “maps into” existing network layers.
{HomeRF Specification modifies existing technology
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Network Layer View
Existing Upper Layers
TCP UDP
IPDECT
HomeRF MAC Layer
HomeRF PHY Layer
CSMA/CAPriorityCSMA TDMA
“Ethernet”Data Path
StreamingMedia Path
Toll-QualityVoice Path
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HomeRF Specification Basics
Contention-based “Wireless Ethernet” Reserved time TDMA
MAC Layer
Beacon
HomeRF Frame
Plus priority access and time reservation
Plus re-transmission option
PHY Layer
0.8, 1.6, 5, 10 Mbps data rates
2.4 GHz FH
Constant envelope FSK modulation
Conventional synthesizer
BACKUP
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MAC Layer Basics
time
Data Networking
Bulk of time is allocated to data networking
1 2Priority Streams
Within data networking time, streaming media sessions get priority access
Voice Calls
Reserved time period based on number of active voice calls
Hop Re-Transmit
If voice packets fail, they can be re-transmitted at the start of the next frequency
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20 ms
fN+5 Data#8Hop
Ack#8
Data#10 Ack#10
Data#9 Ack#9
20 ms
fN Data#1Hop
Ack#1
Data#2 Ack#2
Data#3 Ack#3
All asynchronous traffic
fN+1 Dn#1
Up#1
Data#4BHop
Ack#4
10 ms
Beacon is added for Isochronous traffic and frame length is reduced to 10ms
fN+3 Up#3
Up#1
Data#6BHop
Ack#6
Dn#3
Dn#1
Second call is added
BHop
10 ms
Dn#1
Up#1
Data#5 Ack#5fN+2
BHop
Dn#3
Up#3
Data#7 Ack#7
First call ends. Frame reordered.fN+4
Superframes and Subframes
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Bandwidth Requirements
Application Speed RequiredText 300 bpsTelephone (QoS, Latency) 8 – 64 KbpsColor Image 25 – 2,500 K bytesDigital Photo 1,000 – 10,000 K bytesDigital Music (QoS) 128 – 700 KbpsVideo Conferencing 384 – 2,000 KbpsMPEG-4 SDTV VoD (QoS, jitter) 250 – 750 KbpsMPEG-4 HDTV VoD 720p (QoS, jitter) 4,500 KbpsMPEG-2 HDTV 1080i (QoS, jitter) 20,000 Kbps
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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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Wideband Frequency Hopping
f1 MHz
Base Channel
5 MHz Superchannel
75 1 MHz channels for 1.6 Mbps data and all voice communications
15 5 MHz channels for 5 and 10 Mbps data modes
HomeRF improves performance of 802.11 FHEnabled by FCC rule change in August 2000, ETSI rule change in December 2001
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0’ 85’ 130’ 150’
RANGE: Signal Strength Diminishes with Distance
Throughput
~5 Mbps
~2.5 Mbps
~0.4-0.8 Mbps
0.8-1.6 Mbps
5 Mbps
AdvertisedRange
150’Advertised Data Rate: 10 Mbps
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Performance over Distance
Broadband/ MPG 4 Video
0
1
2
3
4
5
6
10' 20' 30' 40' 50' 60' 70' 80' 90' 100' 110' 120' 130' 140' 150'
No
min
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(Mb
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Source: Practical and Theoretical Calculations
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
ILD
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WA
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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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WA
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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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IEEE 802.11b waits for Interference to go away
2.4 GHz
2.5 GHz
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Frequency
PowerSpectralDensity
Used ISM band (75 MHz)
Average Power Spectrum(10 to 30 MHz)
Next
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Next
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Next
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Next
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Next
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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
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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.
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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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Cost Roadmap parallels DECT
• DECT is a leading indicator for HomeRF– 6 generations of architecture evolution– HomeRF comes in well down the learning curve
• Complexity is similar– HomeRF Baseband ROM/Flash about 2X DECT– Radio will reuse Bluetooth/DECT Low-IF IP
• HomeRF BOM cost will approach DECT at same volumes– Basic HomeRF functionality (voice + 10Mbps)– Additional SW & HW depends on product features
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Cost Synergies
• Easy compatibility with OpenAir– HomeRF and OpenAir share a common PHY
(dual MAC client devices available now)– OpenAir has over 1M devices from over 20
different vendors already deployed in the field
• Multi-mode client devices with Bluetooth– HomeRF and Bluetooth have similar PHY
(multi-MAC client devices, such as a PCMCIA or Compact Flash card, are feasible and expected in 2002)
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Cost Synergies, cont.
• Multi-mode / Multi-band clients– PCS / GSM phones– 802.11b / .11g (DSSS / OFDM)– 802.11b / Bluetooth (DSSS / FHSS)– 802.11b / .11a (2.4 / 5 GHz)– WLAN / WAN (for mobile workers)– Easy to include support for HomeRF
• Adds much needed Flexibility– Automatically sense and adapt to networks
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Bottom Side
IntegratedBaseband
RFIC
Flash
Simple Design: enables Inexpensive 2-chip solutions
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Summary
• 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.
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Wireless Choices for the Broadband Internet home
- Advantage ~ - Adequate X - DisadvantageLegend:
X ~
X ~
Roaming Outside the Home ~ ~ ~
ATTRIBUTE HomeRF Bluetooth 802.11b
Cost
Security
Interference Immunity
Toll-Quality Voice Support
Streaming Media Support
Data Throughput
Range
Power Consumption
Form Factor
Network Topology
~ X
~ X
~
X
X
X ~
X ~
~ ~
~
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