Presentation on theme: "Doc.: IEEE 802.18-07-0096r0 SubmissionFrank Whetten, Boeing Spectrum Alternatives for Aircraft Onboard Wireless Systems Date: 2007-11-13."— Presentation transcript:
doc.: IEEE r0 SubmissionFrank Whetten, Boeing Spectrum Alternatives for Aircraft Onboard Wireless Systems Date:
doc.: IEEE r0 SubmissionFrank Whetten, Boeing Lower frequencies propagate better –Less shadowing and better material penetration, signals will propagate throughout aircraft with low power –Require larger antennas Higher frequencies are more attenuated –More line of sight (LOS) propagation, shadowing and absorption become major factors –Very small antennas can be used, but more power required Desirable to have aviation spectrum near unlicensed bands –Can adapt COTS equipment to avionics use via firmware load –Leverage significant wireless industry investment into technology upgrades and improvements What Kind of Spectrum Do We Want? Filename.ppt | 2
doc.: IEEE r0 SubmissionFrank Whetten, Boeing Essentially all usable spectrum is already allocated to primary and secondary users around the world So how might we find spectrum? Two basic options: 1.Obtain new spectrum by taking it away from an incumbent user Resistance to getting more spectrum allocations will be high Maximum opportunity for new spectrum is above 30GHz 2.Reuse existing spectrum already allocated to aviation Aviation has a large number of dedicated frequency bands allocated in around the world Opportunities exist for more efficient use of existing aviation spectrum –MLS is not deployed, DSB-AM still in use Where Will the Spectrum Come From?
doc.: IEEE r0 SubmissionFrank Whetten, Boeing Best opportunity for new spectrum is above 30GHz: –Line of Sight (LOS) propagation –High absorption due to rain, snow, etc. in atmosphere Resulting intra-airplane usage might be appropriate for: –Very short distance, high-bandwidth applications –Very small devices, but with sufficient power availability Examples of suitable applications might include –LRU-LRU communications within an equipment rack, within the flight deck, or multiple sensors with a nearby data concentrator Examples of ill-suited applications could include –Extremely low-power devices attempting to communicate long distances or in a highly shadowed environment, such as along the length of the fuselage Obtaining New Spectrum
doc.: IEEE r0 SubmissionFrank Whetten, Boeing Existing aviation spectrum is largely below 10GHz –Consequently, the advantages of low frequencies apply Is it be possible to reuse existing spectrum? Many factors apply: –Particular classification of existing spectrum (in ITU terms) –Incumbent system characteristics –Bandwidth potentially available for reuse How can we reuse existing spectrum? Two basic possibilities: –Cognitive – the new systems can detect which parts of the frequency band the incumbent is using, and move elsewhere –Underlayment – the new systems operate at power levels below what the incumbent systems can detect (the UWB model) Reusing Existing Spectrum
doc.: IEEE r0 SubmissionFrank Whetten, Boeing Existing Aeronautical Allocations Avionics Receivers Freq Range (MHz) Allocation (Service) Limiting Footnotes ADF ARNS No limiting footnotes. Service Definition: Aeronautical Radionavigation - A radionavigation service intended for the benefit and for the safe operation of aircraft HF Voice HF Datalink 2-30 AM(R)S AM(OR)S No limiting footnotes. Service Definitions: Aeronautical Mobile (Route) Service – reserved for communications relating to safety and regularity of flight (Air Traffic Control) Aeronautical Mobile (Off-Route) Service - intended for communications, including those relating to flight coordination (Aeronautical Operational Control) Marker Beacon75ARNS The frequency 75 MHz is assigned to marker beacons. Administrations shall refrain from assigning frequencies close to the limits of the guardband to stations of other services which, because of their power or geographical position, might cause harmful interference or otherwise place a constraint on marker beacons. ILS Localizer VHF Data Broadcast VHF Omnirange (VOR) ARNS No AR limiting footnotes. AM(R) – (VHF Radio) allocation by footnote: 5.197A The band MHz may also be used by the aeronautical mobile (R) service on a primary basis, limited to systems that transmit navigational information in support of air navigation and surveillance functions in accordance with recognized international aviation standards. VHF Voice & Data Link AM(R)SNo limiting footnotes. ILS Glide Slope ARNS The use of the band MHz by the aeronautical radionavigation service is limited to Instrument Landing Systems (glide path). DME UAT Mode AC Transponder Mode S Transponder TCAS Interrogator GNSS L5/E ARNS The use of the band MHz by the aeronautical radionavigation service is reserved on a worldwide basis for the operation and development of airborne electronic aids to air navigation and any directly associated ground-based facilities. (WRC-2000)
doc.: IEEE r0 SubmissionFrank Whetten, Boeing Existing Aeronautical Allocations Avionics Receivers Freq Range (MHz) Allocation (Service) Limiting Footnotes AMS(R)S SATCOM No Allocation Footnote Only 5.357A In the bands MHz and MHz, priority shall be given to accommodating the spectrum requirements of the aeronautical mobile-satellite (R) service providing transmission of messages with priority 1 to 6 in Article 44. Aeronautical mobile- satellite (R) service communications with priority 1 to 6 in Article 44 shall have priority access and immediate availability, by pre-emption if necessary, over all other mobile-satellite communications operating within a network. GNSS/ GPS ARNSNo Limiting Footnotes Radio Altimeter ARNS Use of the band MHz by the aeronautical radionavigation service is reserved exclusively for radio altimeters installed on board aircraft and for the associated transponders on the ground. However, passive sensing in the Earth exploration-satellite and space research services may be authorized in this band on a secondary basis (no protection is provided by the radio altimeters). MLS MLS Extension Band ARNS The band MHz is to be used for the operation of the international standard system (microwave landing system) for precision approach and landing. The requirements of this system shall take precedence over other uses of this band Additional allocation: The bands MHz and MHz are also allocated to the aeronautical mobile-satellite (R) service on a primary basis, subject to agreement obtained under No Weather Radar ARNS The use of the band MHz by the aeronautical radionavigation service is limited to airborne radars and associated airborne beacons. Weather Radar No Allocation - Footnote Only The use of the band MHz by the aeronautical radionavigation service is limited to airborne weather radars and ground-based radars. In addition, ground-based radar beacons in the aeronautical radionavigation service are permitted in the band MHz on condition that harmful interference is not caused to the maritime radionavigation service. In the band MHz, ground-based radars used for meteorological purposes have priority over other radiolocation devices.
doc.: IEEE r0 SubmissionFrank Whetten, Boeing What is Cognitive Radio, and what does it have to do with reality? –Cognitive radio is the concept of a coexisting system detecting another system, and moving out of the way –Regulatory authorities world-wide are looking at cognitive as an answer to the shortage of good spectrum –IEEE a/n operation in 5GHz band using DFS is an early implementation of cognitive capability Thus, to reuse existing avionics spectrum the new systems would: –Need to know where the incumbent system is operating, and –Operate around it or under it How? –Announcements (via a systems bus, beacon, etc.) –Detection of emissions (proven, but difficult) Cognitive Approaches
doc.: IEEE r0 SubmissionFrank Whetten, Boeing What is underlayment, and what does it have to do with reality? –Underlaying an existing spectrum allocation relies upon operating a new system in such a way that the existing system is not interfered with in a harmful way (FAA/FCC nomenclature) –Again, a major push by regulators looking for ways to gain more utility from over-desired spectrum Thus, to reuse existing avionics spectrum, the new systems would: –Operate at power levels which would not interfere with the input receivers of incumbent systems How? Two factors: –Output power, directionality, and gain of new system –Interference path loss (IPL) between new system and the incumbent receiving antenna Underlayment Approaches
doc.: IEEE r0 SubmissionFrank Whetten, Boeing Shannons Law –The theoretical maximum bit-rate through any noise-limited channel is –where C=channel capacity in bits, B=channel bandwidth in Hz, and is numeric signal-to-noise ratio Shannons law can be modified by MIMO technology to –Where (H) is a bunch of channel and path correlation factors, and N is the number of MIMO channels How Much Bandwidth is Available?
doc.: IEEE r0 SubmissionFrank Whetten, Boeing How Close to Shannon Are We?
doc.: IEEE r0 SubmissionFrank Whetten, Boeing Underlaying Existing Systems
doc.: IEEE r0 SubmissionFrank Whetten, Boeing Two approaches to obtain dedicated and protected spectrum for intra-airplane use –Pursue a new aviation allocation through international treaties organizations –Develop methodology to re-use existing spectrum in a safe and efficient manner A new allocation –Would likely be challenging to obtain spectrum below 10GHz, due to strong competition for spectrum resources –Would likely take several cycles of the World Radio Conference to approve Reusing existing allocations –Significant engineering challenges in ensuring that multiple communications systems can use the same spectrum without harmful interference –Regulatory challenges pertaining to avoiding being limited by the current regulatory language and footnotes on existing bands Conclusions