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IEEE 802.11n – High Throughput
• Will enable new consumer, enterprise applications• Video distribution, more bandwidth for QoS applications,
greater range, throughput
• High Data rates (64-600Mbps)• A typical 2 transmitter MIMO device will support a 300Mbps data
rate when using 40MHz channel• 144Mbps data rate when using 20MHz channel
• Legacy mode support• Support for Legacy a/b/g, e.g. 802.11n AP and a/b/g STAs• Support for Mixed Mode e.g. 802.11n AP and a/b/g/n STAs
• Green Field 802.11n-only
New components in IEEE 802.11n
• PHY Enhancements, applicable to both 2.4GHz and 5GHz• The new PHY supports OFDM modulation with additional
coding methods, preambles, multiple streams and beam-forming
• Multiple Input Multiple Output (MIMO) Radio Technology With Spatial Multiplexing
• High throughput PHY – 40 MHz channels – Two adjacent 20 MHz channels are combined to create a single 40 MHz channel.
• MAC Enhancements• Two MAC aggregation methods are supported to efficiently
pack smaller packets into a single MPDU• Block Acknowledgement – A performance optimization in which
an IEEE 802.11 ACK frame need not follow every unicast frame and combined acknowledgements may be sent at a later point in time.
What is MIMO?
• Multiple Input Multiple Output (MIMO)• Transmit and Receive with multiple radios simultaneously in same spectrum
channelRadio
Radio
DSP
Bits
TX
Radio
Radio
Radio
DSP
Bits
Radio
RX
• Compare to traditional Single Input Single Output Radio (with optional receive diversity)
channelRadioDSPBits
TXRadio DSP Bits
RX
Spatial Division Multiplexing
Multiple independent data streams are sent between the transmit and receive antennas to deliver more bits in the specified bandwidth
Radio
Radio
DSP
More Bits
TX
Radio
Radio
Radio
DSP
More Bits
Radio
RX
• Cross-paths between antennas are automatically decoded by the receiver, assuming sufficient “richness” in the propagation environment
What Does this Mean to Education
• Pre-N Products will show up in your air– Effective air monitoring & WIDS tools
• Enterprise Draft-N products in 2007– Start pilots for high bandwidth apps– Draft-N clients start to show up in high-end laptops
• Mass adoption in 2008– Standard ratification expected in 1H’2008– Price-performance targets will be met for mass adoption– 802.11n clients will become ubiquitous
• What does this mean to you– Wireless becomes the ONLY connection from PRIMARY– Extending mobile security to legacy wired ports– New high performance 802.11a/b/g/n Access Points– Higher Performance Mobility Controllers
• Control and Data Plane Scaling Intelligence
Agenda
• Introduction to Aruba Networks• 802.11n• Smart Antennas• How Dartmouth Implemented Voice,
Video and Data over Wi-Fi
Smart Antennas for Wi-Fi Stability
Applies MIMO-diversity techniques to standard Wi-Fi
“Intuitive antennas” (continuous learning)
2 to 3X range and performance increase
Active interference rejection
Compatible with all 802.11 standards
Compact internal antenna array Capable of 63 unique antenna patterns
Increased range and better performance in any direction at any time
Expert control software constantly ranks optimum antenna patterns for each receiving device Six high-gain
directional antenna elements
Avoiding Interference with Smart Antennas
Family Room
Bedroom Home office
Kitchen
Interference fromneighboring network
BeamFlexPowered
Set Top Box
Ruckus AP
1
2
3
1
Microwave
2
What Interference Avoidance Looks Like
Ruckus 2900 AP to Off-the-Shelf 802.11g Client Off-the-shelf 802.11 AP to Off-the-Shelf 802.11g Client
Ruckus 2900 AP to Ruckus 2501 Client • 3-minute throughput measurements per test
• Microwave on after 1st minute for 1-minute
AP
Client
Microwave
30 ft
What About 802.11n?
Spatial multiplexing improves top line bandwidth Critical for HD streaming
(WMV-9 at 9-12 Mbps per stream)
Multiple signals increase chance of experiencing interference, decreases the chance of Wi-Fi stability
Streams take different paths making it harder to recover at receiving end
No predictability - at the mercy of wild signal scattering
No inherent QoS
Smart Wi-Fi technology sits on top of 802.11n fixing these problems
More Wi-Fi Capacity is Good but Not Good Enough
Giving 802.11n StabilityData Grade Performance
(@ 50 Percentile of Throughput Distribution)*
Video Grade Performance (@ 99.5 Percentile of Throughput
Distribution)*
Test Environment & Methodology
• 3,000 sq-ft, 2-story US Residential House
• UDP echo test
• 5,000 measurements taken per AP per location at 50ms intervals; measurements sorted by distribution to report the throughput at 50th and 99.5th percentiles
Test Date: May 08, 2006
5 ft, LOS
26 ft, 1
stucco wall
56 ft, 1 stucco
& 1 granite walls
41 ft, 2 stucco
& 2 exterior walls & bathroo
m
40 ft upstairs,
3 stucco
walls and 1 floor
5 ft, LOS
26 ft, 1
stucco wall
56 ft, 1 stucco
& 1 granite walls
41 ft, 2 stucco
& 2 exterior walls & bathroo
m
40 ft upstairs,
3 stucco
walls and 1 floor
Ruckus 2221AP & 2501 Adapter (Atheros 802.11b/g Chipset)
Netgear RangeMax 240 Router & PC Card (Airgo Gen3 MIMO Chipset)
Netgear RangeMax Next Gigabit Edition Router & PC Card (Marvell Draft-N Chipset)
MIMO, Draft-N
BeamFlex on Standard .11G
BeamFlex over .11N