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TRANSCRIPT
Wireless Common Sense
Shifting the Collection of Prejudices
Robert J. Berger Internet Bandwidth Development Consulting
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Common senseis the collection of
prejudices acquired by age eighteen- Albert Einstein
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Tech You Grew Up with Shapes your Prejudices of Wireless Tech Capabilities
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Tech You Grew Up with Shapes your Prejudices of Wireless Tech Capabilities
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Claude Shannon’s Communications
Theory Shows us the Reality beyond our prejudices
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C=W log (1+S/N)
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Shannon’s Theory
where; C=channel capacity (bits/second)
C=W log (1+S/N)
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Shannon’s Theory
where; C=channel capacity (bits/second)W=Bandwidth (How much Spectrum we are using)
C=W log (1+S/N)
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Shannon’s Theory
where; C=channel capacity (bits/second)W=Bandwidth (How much Spectrum we are using)
S=signal power, and N=noise power
C=W log (1+S/N)
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Propagation Characteristics & Path Loss
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Propagation Characteristics & Path Loss
• Determines how much of the signal power gets to the receiver
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Propagation Characteristics & Path Loss
• Determines how much of the signal power gets to the receiver
• The higher the frequency- the less easily the signal propagates
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Propagation Characteristics & Path Loss
• Determines how much of the signal power gets to the receiver
• The higher the frequency- the less easily the signal propagates
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Propagation Characteristics & Path Loss
• Determines how much of the signal power gets to the receiver
• The higher the frequency- the less easily the signal propagates- The more buildings, trees, hills the
more attenuation
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Propagation Characteristics & Path Loss
• Determines how much of the signal power gets to the receiver
• The higher the frequency- the less easily the signal propagates- The more buildings, trees, hills the
more attenuation
• Physical Reality is such a Drag!!
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Radio & TV: Broadcast HIGH POWER & low frequency
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Radio & TV: Broadcast HIGH POWER & low frequencyMEGA WATTS of Power!!!
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Radio & TV: Broadcast HIGH POWER & low frequencyMEGA WATTS of Power!!!
Spectrum in the 80 - 800 MHz range
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Radio & TV: Broadcast HIGH POWER & low frequencyMEGA WATTS of Power!!!
Spectrum in the 80 - 800 MHz range
50Khz - 6Mhz Channel Bandwidth
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Radio & TV: Broadcast HIGH POWER & low frequencyMEGA WATTS of Power!!!
Spectrum in the 80 - 800 MHz range
50Khz - 6Mhz Channel Bandwidth
Gets Large Channel Capacity via Power and Significant Spectrum
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Tech from the 1930’s
Very simple analog modulationUses spectrum inefficiently
Receiver has difficulty rejecting noise
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Cell Phones: Tiny Channel Capacity
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Cell Phones: Tiny Channel Capacity
Low Signal Power & Advanced Modulation
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Cell Phones: Tiny Channel Capacity
Low Signal Power & Advanced Modulation
800 - 1900Mhz a bit more difficult propagation, but still good
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Cell Phones: Tiny Channel Capacity
Low Signal Power & Advanced Modulation
800 - 1900Mhz a bit more difficult propagation, but still good
But only requires 4kbps Channel Capacity
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Cell Phones: Tiny Channel Capacity
Low Signal Power & Advanced Modulation
800 - 1900Mhz a bit more difficult propagation, but still good
But only requires 4kbps Channel Capacity
High speed data phones will have less coverage or need more basestations
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Past Experience Does Not Apply to WiFi
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Past Experience Does Not Apply to WiFi
Uses Unlicensed Spectrum2.4Ghz & 5 - 6Ghz, Very Low Power
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Past Experience Does Not Apply to WiFi
Uses Unlicensed Spectrum2.4Ghz & 5 - 6Ghz, Very Low Power
Rapid comidification & evolution -Very low cost & advanced modulation
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Past Experience Does Not Apply to WiFi
Uses Unlicensed Spectrum2.4Ghz & 5 - 6Ghz, Very Low Power
Rapid comidification & evolution -Very low cost & advanced modulation
Developed “Bottoms Up” like the Internet, not from Carriers or
Broadcasters
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Unlicensed Wireless Constraints
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Unlicensed Wireless Constraints
Original Spectrum considered “Junk Spectrum”2.4Ghz is absorption frequency of water5 - 6 Ghz propagates about 1/2 as well
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Unlicensed Wireless Constraints
Original Spectrum considered “Junk Spectrum”2.4Ghz is absorption frequency of water5 - 6 Ghz propagates about 1/2 as well
Can’t interfere, but must accept interference
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Unlicensed Wireless Constraints
Original Spectrum considered “Junk Spectrum”2.4Ghz is absorption frequency of water5 - 6 Ghz propagates about 1/2 as well
Can’t interfere, but must accept interference
Very low power, but lots of spectrumVery low power, but lots of spectrum
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Unlicensed Wireless Constraints
Original Spectrum considered “Junk Spectrum”2.4Ghz is absorption frequency of water5 - 6 Ghz propagates about 1/2 as well
Can’t interfere, but must accept interference
Very low power, but lots of spectrum
Very short distance with high bandwidth
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Average WiFi Link Budget
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Average WiFi Link Budget
AP to Client limited by weakest linkAvg clients’ Signal Power: 15dBmAvg AP Sensitivity 1Mbps: -94dBm
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Average WiFi Link Budget
AP to Client limited by weakest linkAvg clients’ Signal Power: 15dBmAvg AP Sensitivity 1Mbps: -94dBmLink Budget avg client to AP:
signal power + xmit antenna gain - free space path loss + receiv antenna gain - receive
sensitivity = Margin
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Average WiFi Link Budget
AP to Client limited by weakest linkAvg clients’ Signal Power: 15dBmAvg AP Sensitivity 1Mbps: -94dBmLink Budget avg client to AP:
signal power + xmit antenna gain - free space path loss + receiv antenna gain - receive
sensitivity = Margin15dBm + 2dB - (-84) + 7dB - (-94dBM) =
34 dBm Margin at 150 Meters
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Link Margin
150
125
100 75 50 25
24 2628
3134
40
35 3739
4245
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1 Mbps 11 Mbps
Meters
Link
Mar
gin
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Link MarginThe Free Space Loss calculations are optimistic
150
125
100 75 50 25
24 2628
3134
40
35 3739
4245
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1 Mbps 11 Mbps
Meters
Link
Mar
gin
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Link MarginThe Free Space Loss calculations are optimistic
Realistic distance of a laptop to an AP is ~30m in the open
150
125
100 75 50 25
24 2628
3134
40
35 3739
4245
51
1 Mbps 11 Mbps
Meters
Link
Mar
gin
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Link MarginThe Free Space Loss calculations are optimistic
Realistic distance of a laptop to an AP is ~30m in the open
At 150 Meters, One good tree will knock out your link 15
012
510
0 75 50 25
24 2628
3134
40
35 3739
4245
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1 Mbps 11 Mbps
Meters
Link
Mar
gin
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Real World Constraints
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Real World ConstraintsWiFi originally designed for indoor LAN
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Real World ConstraintsWiFi originally designed for indoor LAN
WiFi CSMA does not handle large numbers of clients accessing an AP
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Real World ConstraintsWiFi originally designed for indoor LAN
WiFi CSMA does not handle large numbers of clients accessing an AP
Nearby clients and APs not associated to an SSID can cause contention
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Real World ConstraintsWiFi originally designed for indoor LAN
WiFi CSMA does not handle large numbers of clients accessing an AP
Nearby clients and APs not associated to an SSID can cause contention
Asymmetrical Power causes client misbehavior
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Real World ConstraintsWiFi originally designed for indoor LAN
WiFi CSMA does not handle large numbers of clients accessing an AP
Nearby clients and APs not associated to an SSID can cause contention
Asymmetrical Power causes client misbehavior
Obstructions: One Tree: 20dB One Wall: 10dB
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WiFi has to Evolve Around Limitations
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WiFi has to Evolve Around Limitations
802.11 Phy has already evolved from 1Mbps to 802.11n with 125Mpbs
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WiFi has to Evolve Around Limitations
802.11 Phy has already evolved from 1Mbps to 802.11n with 125Mpbs
Distance not really improved (but more bandwidth for same short distance)
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WiFi has to Evolve Around Limitations
802.11 Phy has already evolved from 1Mbps to 802.11n with 125Mpbs
Distance not really improved (but more bandwidth for same short distance)
Contention by nearby nodes not addressed yet (802.11s may, Proprietary extensions today)
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WiFi Recapitulates Ethernet Evolution
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WiFi Recapitulates Ethernet Evolution
Originally Considered a “Toy”
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WiFi Recapitulates Ethernet Evolution
Originally Considered a “Toy”
Started out as LAN evolved to MAN
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WiFi Recapitulates Ethernet Evolution
Originally Considered a “Toy”
Started out as LAN evolved to MAN
“Good Enough” and much less expensive
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WiFi Recapitulates Ethernet Evolution
Originally Considered a “Toy”
Started out as LAN evolved to MAN
“Good Enough” and much less expensive
Designed by NetHeads, not BellHeads
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WiFi Recapitulates Ethernet Evolution
Originally Considered a “Toy”
Started out as LAN evolved to MAN
“Good Enough” and much less expensive
Designed by NetHeads, not BellHeads
Continually pushed beyond original limitations, first by proprietary extensions,
that migrate to standards
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WiFi Recapitulates Ethernet Evolution
Still at the Hub & Bridge
Stage Compared toEthernet Evolution
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Mesh: Ideal Architecture for Unlicensed Bands
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Mesh: Ideal Architecture for Unlicensed Bands
• Take advantage of
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Mesh: Ideal Architecture for Unlicensed Bands
• Take advantage of- Limited range
150
125
100 75 50 25
24 26 2831
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4035 37 39
4245
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Mesh: Ideal Architecture for Unlicensed Bands
• Take advantage of- Limited range- Low Cost
components
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Mesh: Ideal Architecture for Unlicensed Bands
• Take advantage of- Limited range- Low Cost
components- Good amount of
Spectrum
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Mesh: Ideal Architecture for Unlicensed Bands
• Take advantage of- Limited range- Low Cost
components- Good amount of
Spectrum- Millions of Nodes
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Not Yet Near the Ideal
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Not Yet Near the IdealSome use 2.4Ghz for backhaul & access!
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Not Yet Near the IdealSome use 2.4Ghz for backhaul & access!
Uses standard 802.11 CSMA protocol
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Not Yet Near the IdealSome use 2.4Ghz for backhaul & access!
Uses standard 802.11 CSMA protocol
Gives great demo: Works great unloaded
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Not Yet Near the IdealSome use 2.4Ghz for backhaul & access!
Uses standard 802.11 CSMA protocol
Gives great demo: Works great unloaded
As usage grows, contention is multiplied & becomes unusable
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Not Yet Near the IdealSome use 2.4Ghz for backhaul & access!
Uses standard 802.11 CSMA protocol
Gives great demo: Works great unloaded
As usage grows, contention is multiplied & becomes unusable
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Today’s Best Practices for Mesh
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Today’s Best Practices for Mesh
Use different bands for Mesh & Access
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Today’s Best Practices for Mesh
Use different bands for Mesh & Access
Coordinate transmissions & directional antennas
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Today’s Best Practices for Mesh
Use different bands for Mesh & Access
Coordinate transmissions & directional antennas
Multiple Mesh Radios pluses and minuses
Features
Wireless! High-performance, multi-node and
multi-radio mesh architecture.! Low latency and high throughput
across multiple wireless hops.! Up to six radios per node
(upgradeable).! Full duplex mesh.
System! All nodes auto-discover and self-
configure.! Self-tuning and self-healing mesh
for network optimization.! User definable QoS with voice,
video and data prioritization.! Up to 16 BSSIDs per radio.! Multiple SSIDs (per network and
per node) and VLAN tagging, withconfigurable security parameterson a per-SSID basis.
! Session persistence for roaming,path optimization or failover.
! Manager/One® Web interfaceprovides a full suite of intuitivemanagement tools at the network,node, and radio levels.
! Additional remote managementoptions include SNMP, CLI overTelnet or SSH, HTTP/HTTPS,DHCP, and BOOTP.
! Seamless interoperability with theStrix Access/One® Indoor WirelessSystem (IWS) and Edge WirelessSystem (EWS).
Security! Supports all industry standard
security protocols.! RADIUS, WPA, EAP-MD5, EAP-
TLS, PEAP-TTLS authentication.! 802.11i with AES, WEP and TKIP
encryption.! MAC address Access Control Lists
on a per SSID basis.! Full VPN support.
OWS 3600 SERIES
DELIVERS INDUSTRYÊÂS HIGHEST THROUGHPUT,LOWEST LATENCY ACROSS MULTIPLE HOPS
The award winning Access/One® Outdoor Wireless System (OWS) 3600 is theindustry’s highest highest throughput, lowest latency modular multi-radio meshnetworking system. Utilizing Strix DMATM, the Access/One OWS delivers multi-radio, multi-RF and multi-channel capabilities usingadvanced algorithms to deliver high throughput overmultiple hops from the core to the edge of the network.The OWS intelligently self-tunes, self-configures andself-heals to optimize the overall performance andavailability. The OWS architecture makes 802.11 a fullduplex technology, moving traffic more efficientlythrough the network and utilizing different RFfrequencies and channels for network connectivity andclient access. RF Channels are selected dynamically,making the network more resilient to interference thanstandard mesh networks. Working closely together,these features deliver higher throughput and lowerlatency across multiple hops, supporting real timevoice, video, and data applications. The OWS scales
efficientlyand econ-omicallyminimizing the number of wiredtermination points required in thenetwork, greatly reduces deploymentand operating costs and the Total Costof Ownership (TCO). Extendedoperating temperature ranges andflexible mounting options make theOWS suitable for all types of
deployment scenarios. All OWS nodes can be centrally managed managed usingthe Manager/One® secure Web interface, or the carrier grade SNMP basedmanagement tools. Enhanced features including Virtual/Strix, Priority/One andRogue/One support deployments of mixed use networks where varying securityschemes are implemented based on user type and different levels of priority canbe assigned to the various network traffic. Access/One Network OWS is an idealsolution for carriers, service providers, municipalities, public safety, federalgovernment applications and more.
OWS is the most secure meshnetworking systemavailable, with
the tools to authenticate users,encrypt wireless traffic, andmonitor network activity all
provided as standard features.Secure private networks canoperate in tandem with open
public access networks—with dataintegrity guaranteed.
Strix Systems, Inc.26610 Agoura Road,Calabasas, CA 91302 USA
1-877-STRIXSYS (787-4979) Toll FreeWeb Site: www.strixsystems.com
www.strixsystems.com
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Today’s Best Practices for Mesh
Use different bands for Mesh & Access
Coordinate transmissions & directional antennas
Multiple Mesh Radios pluses and minuses
Multiple tiers of Wireless backhaul
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Today’s Best Practices for Mesh
Use different bands for Mesh & Access
Coordinate transmissions & directional antennas
Multiple Mesh Radios pluses and minuses
Multiple tiers of Wireless backhaul
Expect < 1Mbps delivered19
State of Muni-Wireless(US Centric View)
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State of Muni-Wireless(US Centric View)
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State of Muni-Wireless(US Centric View)
First phase build-outs
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State of Muni-Wireless(US Centric View)
First phase build-outs
Significant Learning Curve
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State of Muni-Wireless(US Centric View)
First phase build-outs
Significant Learning Curve
First Generation Equipment
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State of Muni-Wireless(US Centric View)
First phase build-outs
Significant Learning Curve
First Generation Equipment
Be prepared for negative Hype CyclePeople’s expectations too high
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State of Muni-Wireless(US Centric View)
First phase build-outs
Significant Learning Curve
First Generation Equipment
Be prepared for negative Hype CyclePeople’s expectations too high
Its still very early
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WiMax?
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WiMax?If WiFi recapitulates
the evolution of Ethernet;WiMax recapitulates the
evolution of all of Ethernet’s competitors
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WiMax?
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WiMax?No real advantage when comparing unlicensed
WiMax & WiFi
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WiMax?No real advantage when comparing unlicensed
WiMax & WiFi
Licensed WiMax can be useful(ATM was useful for some things too)
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WiMax?No real advantage when comparing unlicensed
WiMax & WiFi
Licensed WiMax can be useful(ATM was useful for some things too)
Getting a License can be difficult & Expensive
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WiMax?No real advantage when comparing unlicensed
WiMax & WiFi
Licensed WiMax can be useful(ATM was useful for some things too)
Getting a License can be difficult & Expensive
Very good for feeding WiFi Mesh
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WiMax?
Beware of Hype
Very few deployments of “real” WiMax
No deployments of Mobile WiMax
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Wireless Tech of the Future
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Wireless Tech of the Future
• Ultrawideband- Ultra Short Range- 2 to 3 x bandwidth
over 802.11n
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Wireless Tech of the Future
• Ultrawideband- Ultra Short Range- 2 to 3 x bandwidth
over 802.11n
• 60 - 70 Ghz- Extreme Bandwidth &
Directionality
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Wireless Tech of the Future
• Ultrawideband- Ultra Short Range- 2 to 3 x bandwidth
over 802.11n
• 60 - 70 Ghz- Extreme Bandwidth &
Directionality
• Super Mesh- 802.11s evolution?- Short Range is good- More Bandwidth!
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Wireless Tech of the Future
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Wireless Tech of the Future
No Silver Bullets on the Horizon
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Wireless Common Sense
Shifting the Collection of Prejudices
Robert J. Berger Internet Bandwidth Development Consulting
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