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BANC – Bro adband Access Network Coordination. A practical solution to the critical problem of interference in the unlicensed spectrum bands. Graham Barnes, CEO NextWeb, Inc. Overview. Critical Problem of Interference in Unlicensed Bands with a Multi-Operator Environment
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BANC – Broadband Access Network Coordination A practical solution to the critical problem of interference in the unlicensed spectrum bands Graham Barnes, CEO NextWeb, Inc.
Overview • Critical Problem of Interference in Unlicensed Bands with a Multi-Operator Environment • There are Successful Interference Countermeasures • Unlicensed does NOT mean Uncoordinated • Unlicensed does NOT mean Unreliable • Unlicensed does NOT mean Uninvolved
Why is Interference Getting Worse – Not Better? • Weren’t technology improvements supposed to eliminate interference? • Spread spectrum • Adaptive modulation • Multi-carrier techniques • New frequency bands • More payload • More users / operators • Lower cost equipment • Unrealistic expectations?
Why is a Frequency Management Program Important? • Even if you don’t have interference problems today – you will! • Private parties deploying campus systems • School districts and cities deploying unlicensed WANs • New wireless ISPs entering the market • Investor confidence
Frequency Management Program Tools • Terrain Map-based Engineering Plans • Open Disclosure of NextWeb Network • Interference Countermeasures • Knowledge of Channel Plans from Major Vendors • Spectrum Analyzer Surveys to Monitor and Identify Use • Active Participation in Coordination • Joint, Controlled Interference Resolution
Terrain Map-Based Engineering • Anticipated coverage expectations
Terrain Map-Based Engineering • Not all problems are due to interference
Interference Countermeasures • Directional antennas • Narrow Channels • Short paths • Max C/I • Vendor technology • Good contracts
What does not work? • More transmitter power • Adjacent channels • Complaints from other operators • Self interference • Uncontrolled rooftops • Interference protection language in contracts • Seeing other WISPs as “the competition” instead of partners • Telco/cable monopolies are “the competition” • Blind faith in the claims of the vendors’ marketing departments
Sample Channel Plans from Major Vendors • 5.8 GHz • ISM • UNII
Sample 5.8 GHz Spectrum Nearby Axxcelera Nearby Trango Axxcelera Unknown Axxcelera Trango w/Unknown Trango Unknown
Active Participation in Coordination Cellular 5.8 GHz PTP 5.8 GHz PMP 5.8 GHz PMP Cellular Cellular 5.8 GHz PMP One corner of shared base station
Opposite Corner of Same Building Cellular Axxcelera 5.8 GHz PMP 23 GHz 18 GHz 11 GHz 18 GHz 5.3/5.8 GHz PTP
SU SU SU SU SU SU SU SU SU SU Joint, Controlled Interference Resolution SU SU SU SU AP SU SU AP Initial Status: Three different fixed wireless providers (red, green and blue), built out their unlicensed networks in the same area, over time. By careful selection of frequency channels, all three operators are able to provide reliable interference-free connections from their access points (APs) to their customers’ subscriber units (SUs). SU SU AP AP SU SU SU SU SU AP
SU SU SU SU SU SU SU SU SU SU Joint, Controlled Interference Resolution SU SU SU SU AP SU SU AP SU Enter a rogue interferer: A new unlicensed link (yellow) is turned on, causing interference to one of the green operator’s subscribers resulting in significant bit or frame losses. The areas of influence of the new link’s transmitters are shown as yellow circles. SU AP AP SU SU SU SU SU AP
SU SU SU SU SU SU SU SU SU SU Joint, Controlled Interference Resolution SU SU SU SU AP SU SU Typical scenario: The green operator sees interference, but the red and blue operator does not. However, the green operator attempts to switch his AP to a new channel to avoid the interference. The new channel now causes interference to red and blue operators who must also change channels, if possible. AP SU SU AP AP SU SU SU SU SU AP
SU SU SU SU SU SU SU SU SU SU Joint, Controlled Interference Resolution SU SU SU SU AP SU With BANC pre-coordination: Thegreen operator sends out a group message to make sure no BANC member has made a change. As no member made an uncoordinated change, thegreen operator concludes that a new private link is causing interference. Thegreen operator lets the BANC group know of the proposed channel change of his AP. BANC group helps coordinate to find a good channel solution so no NEW interference problem occurs. SU AP SU SU AP AP SU SU SU SU SU AP
www.wbanc.com • Why should I join? • Protect revenues and predictable performance • High cost of interference • Cannot afford a glitch: churn; time • Hard to identify and resolve a case of interference on your own • What are the rules? • No fees • New members welcomed • Neutral exchange of information by web and e-mail (yahoo groups) • Survey first before turning on transmitter • Pre-coordinate prior to installing or changing freq
BANC policies • Declaration • Subsequent operators must use due dilligence to determine and avoid existing spectrum in use • Those who disrupt existing operations are offered the opportunity to correct before civil legal action • Protocols • Scan spectrum first before operating • Advise other operators of tests by e-mail in advance • Send out warning and seek consultation when attempting to correct cases of interference
Growth of BANC • Reach out to encourage participation • Other WISPs • Other users of outdoor unlicensed equipment • Vendors • FCC / DoD • Multiple regional BANC groups • All linked to central web site • Find out if there is a BANC group in your region • Seek participation nationally • Learn from best practices • Occasional meetings hosted by participants, rotating basis
Future of Unlicensed Broadband • Regulators love unlicensed • Responsive to the needs of industry • Deregulation aids tight budgets • We must push for more spectrum and more flexibility • Technology to the rescue! • Cognitive radio – when? • The “list”: always-on, non-LOS, increased range, blg penetration, high throughput, VoIP quality, $300 CPE • Potential Explosive Growth • Economy rebounds • NextGen equipment ships • Financial markets wake up to potential