Implications of Spectrum Management for the Air Force. Paul J Kolodzy, PhD Kolodzy Consulting, LLC

Transcription

1 Implications of Spectrum Management for the Air Force Paul J Kolodzy, PhD Kolodzy Consulting, LLC

2 Studies of the RF Spectrum DoD Defense Science Board, Army Science Board US Gov t FCC (SPTF), WH/DoC Non-Gov t CSIS, Toffler, CSTB, NRC Common Theme: Technology continues to increase both the uses of the RF Spectrum as well as the capacity to more intensively use the RF Spectrum Coordination/Cooperation both administratively and technically is needed to improve capacity Technology is challenging current spectrum management and spectrum policy paradigms

3 Multi-Disciplinary Not just in Words transaction highest and costs best use OOBE auctions Structure Programming Computer Scientists Policy Makers LNA db child processes Intermods dynamic range Provability Ontologies Electrical Engineers, Computer Scientists, Communications Engineers, Lawyers, Policy Makers, Economists, Physicists, Material Scientists, Pontificators Electical Engineers Economists

4 Summary Technology for Dynamic Use of the RF Spectrum continues to improve (DoD and Commercial); Use of RF Spectrum continues to increase and the need for more intensive use of RF is necessary to meet future needs; USAF needs to address fundamental characteristics of RF Spectrum needs and uses More Exploitation of Networking, Smart Antennas, Multi-mode (RF/non-RF) Technologies More Intensive Use through Time-Frequency-Space Sharing with Federal & non-federal Users

5 Technology Update Software Defined Radios next Generation Communications (XG) Cognitive Radios Policy Radios XG / Dynamic Spectrum Access Technology has been demonstrated for both military and commercial applications MANET Networking has been demonstrated successfully with smaller (<50 node) networks Extensions to High Density Networks on-going at DARPA Power Amplifier / Filter Technology has lagged Multiple Programs at DARPA and other DoD Laboratories Optical Networking for Tactical Backhaul TRL-6 Project at DARPA

6 Layer-3 3 Interoperability DARPA - NCRS

7 Commercial Technology Enablers Smart Antennas Orthogonal Frequency Division Multiple Access (OFDMA) time frequency Adaptive Modulation 256 QAM 64 QAM 16 QAM QPSK BPSK Technology Enablers Smart Antennas Increases Wireless Performance Adaptive Modulation Exploits Stronger Signals for Increased Capacity OFDMA More Efficient Resource Utilization

8 The New Challenge FDD (Commercial) TDD (DoD( DoD) Uplink Downlink ~30 to 300 MHz Block 1 Block 2 Block 1 Block 2 Uplink/ Downlink AWS-3-43 dbw -43 dbw -43 dbw Base Base Interference FDD Downlink TDD Uplink Mobile Mobile Interference FDD Downlink TDD Uplink Mismatch between Commercial Technology (commonly FDD) and DoD Technology (commonly TDD) requires better technology development to make more compatible

9 The Computer Science View of Interference Avoidance QPSK Interference Spectrum Shaped 128 kbps 0-10 Tx Spectrum Power Spectrum Magnitude (db) Frequency (Hz) x 10 6 Rcv Spectrum Power Spectrum Magnitude (db) Frequency (Hz) x Normal 3 Survive 2 Survive Transmission Number Power Spectrum Magnitude (db) Frequency (Hz) x Normal 3 Survive 2 Survive Transmission Number

10 Regulatory Rules Band 1 Band 2 Band 3 Out-of-Band Emissions (OOBE) OOBE Intermodulation Distortion (IMD) f 1 f 2 2f 2- f 1 Interference Level Dependent Upon Emitted signal levels Frequency separation between signals Transmit and receive filtering Desired signal level at victim receiver Near-Far Scenario

11 The Radio Engineering View of Interference Cumulative Energy in Receiver Filter Increases Noise Floor, Reducing Detection Distance Combination of multi-band operation and high spectrum use can create significant challenges High dynamic range vs. low-power consumption Current technology is challenged to allow sensitive reception in the presence of strong signals and densely occupied spectrum Signal Environment ~20 dbm Increase in Noise Floor Receiver Output ~88% Reduction in Spectrum Availability DARPA Tuner Utilization Study, PR #8587, Shared Spectrum Company Results Shown for Ultra High Quality LNA 10dB Gain, IIP3 = 50dBm, 10W consumption

12 Open Spectrum/Channel Use Intermodulation Distortion (IMD) Signal Power = -70dBm, Gain 10 db, Amplifiers IP3 = -7 dbm Input Power Level per 1.25 MHz OFDM= -40dBm -90 IIP3=-7 dbm dbm -90 Total Input Receiver Output without Total Output Base Output Additional Signal Present dbm Signal Power = -70dBm, Gain 10 db, Amplifiers IP3 = -7 dbm Input Power Level per 1.25 MHz OFDM= -31dBm Total Input Total Output Base Output Interference dbm IMD -110 Power (dbm) per Hz Degradation Power (dbm) per Hz Frequency (MHz) AWS Signal 1 New Signal AWS Signal Frequency (MHz) AWS Signal 1 New Signal AWS Signal 2 Insertion of Signal May Create Out of Band Interference Appears proper when viewed as white space Actual result is a reduction in SNR, resulting in potentially harmful interference This is why Carrier Colocate Transmitters!

13 DSA for Interference Avoidance?! Radio that Can Estimate the Interference Environment, Can Search for Spectral Regions that Do Not Create Interference for the Radio Interference-Free Zones? Dynamic Interference Avoidance Radio Systems combine the understanding of both the RF environment and the Radio RF characteristics

14 Dynamic Interference Avoidance Signal Power = -50dBm, Gain 10 db, Amplifiers IP3 = -7 dbm Input Power Level per 1.25 MHz OFDM= -31dBm Signal Power = -50dBm, Gain 10 db, Amplifiers IP3 = -7 dbm Input Power Level per 1.25 MHz OFDM= -31dBm Total Input Total Output Base Output Total Input Total Output Base Output Power (dbm) per Hz -100 Power (dbm) per Hz Frequency (MHz) Frequency (MHz) Signal Power = -50dBm, Gain 10 db, Amplifiers IP3 = -7 dbm Signal Power = -50dBm, Gain 10 db, Amplifiers IP3 = -7 dbm Input Power Level per 1.25 MHz OFDM= -31dBm Input Power Level per 1.25 MHz OFDM= -31dBm Total Input Total Input Total Output Total Output Base Output Base Output Power (dbm) per Hz -100 Power (dbm) per Hz Frequency (MHz) Frequency (MHz) NG Radios that are Aware of Interference Effects Can Adapt to Mitigate Effects

15 Where s the Action? circa 2007 TV Whitespaces Upper 700 MHz BRS UNII 3.5 GHz

16 US Spectrum Allocations (Government, Non-Government, Shared) 22% 42% 35% Spectrum from 322-3,100 MHz: NTIA regulates 22% FCC regulates 35% Shared NTIA/FCC regulates 42% Frequency Agility and Wideband and Ultra-Wideband Devices, creates Challenges at the Interfaces between the Different Allocations

17 Spectral Utilization High Peak-to-Average Ratio utilization in some bands provide impetus for new thinking in RF Spectrum sharing Technology to provide insight into utilization is prevalent

18 RF Spectrum Sharing Time-Frequency Frequency-Space-Angle-etcetc Demonstrations of Directionality Orthogonality for RF Spectrum Sharing have been Successful (Northpoint)

19 Summary Technology for Dynamic Use of the RF Spectrum continues to improve (DoD and Commercial); Use of RF Spectrum continues to increase and the need for more intensive use of RF is necessary to meet future needs; USAF needs to address fundamental characteristics of RF Spectrum needs and uses More Exploitation of Networking, Smart Antennas, Multi-mode (RF/non-RF) Technologies More Intensive Use through Time-Frequency-Space Sharing with Federal & non-federal Users