![LTE Simulation (Macros,Outdoor Small Cells)
•Antenna Pattern for Macro LTE BS
•3GPP-compliant system-level simulator.
•3GPP-defined macro, small-cell and indoor scenarios.
•Utilizes proportional-fair scheduler in both time and frequency domains.
•Detailed UL air interface modeling, UL MIMO, and receiver diversity.
•Non-ideal link adaptation with Hybrid ARQ.
•EESM link-to-system mapping.
•More precisely modeling Turbo decoder saturation.
•Updated SC-OFDMA SINR calculation with radar interference present.
•pilot symbols for Base Stations Interference Measurements.
13GPP TR 36.814 V9.0.0 (2010-03), “Further advancements for E-UTRA physical layer aspects”, Release 9.
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Parameters Value
Operating Frequency 3.5 GHz
Layout
Hexagonal macro cell grid,
clustered small cells
Mode TDD
Macro/Small Cells BS TX Power 46/30 dBm
UE Transmit (TX) Power 23 dBm
Macro-cell sites/cells 7/21 (3 cells per site)
Outdoor Small cells 84 (4 per macro cell)
Indoor UE ratio for Macro/Outdoor Small
cells
80% / 20%
Bandwidth for Macro / Small cells 20 MHz
BS Antenna Gain for Macro / Small cells 17/ 5 dBi
UE Antenna Gain 0 dBi
Macro Inter-site Distance (ISD) for Uma/Umi 500 m
Minimum UE-BS Distance for Uma/Umi 25 / 5 m
BS Antenna Downtilt for Macro 12 deg
BS Antenna for Small Cells Omni-directional
BS Antenna Height Uma/Umi/InH 25 ,10
UE Antenna Height 1.5m
UE Distribution for Macro / Small cells Uniform/Clustered
UE Mobility 3 km/h, uniform direction
BS/UE Noise Figure (NF) 5/9 dB
Thermal Noise -174 dBm/Hz
Service Profile Full buffer best effort
UEs per Cell for Macro / Small cells 10 / 30
Channel Model for Macro / Small cells UMa / Umi [1]](https://image.slidesharecdn.com/e2c6e60d-39cc-4fd1-a0ed-69578c1a3103-150318134741-conversion-gate01/85/RadarWCNC-7-320.jpg)
RadarWCNC
- 1. TED AND KARYN HUME CENTER FOR NATIONAL SECURITY AND TECHNOLOGY Radar Inband and Out-of-Band Interference into LTE Macro and Small Cell Uplinks in the 3.5 GHz Band Mo Ghorbanzadeh, Eugene Vistosky, Prakash Moorut, Weidong Yang, Charles Clancy 3/11/2015 http://www.hume.ictas.vt.edu UNCLASSIFIED//FOR OFFICIAL USE ONLY
- 2. Data Volume Challenges and Potential Solutions UNCLASSIFIED//FOR OFFICIAL USE ONLY • Mobile broadband spectrum is limited; more bandwidth needed. – Spectrum is scarce, expensive, & crowded. Certain portions are underutilized1. – Overprovisioning: NOT a solution (uneconomical and data hungry apps). – Dynamic spectrum access (DSA): part of a solution. • Results in spectrum efficiency and adaptability by using spectrum holes. – Spectrum is a congested environment. • Spectrum sharing: for example 3.5 GHz band - traditionally for radar and satellite systems. – Incumbents still may use the bands. So spectrum is a contested environment. • Spectrum auctions: for example 600 MHz band - traditionally Television White Space (TVWS). • Radio resource allocation (RRA) should be spectrum augmentative. 1Spectrum Occupancy Measurements of the 3550–3650 MHz Maritime Radar Band Near San Diego, California, NTIA TR-14-500, 2014.
- 3. • National Telecommunications and Information Administration (NTIA) identified existing 3.5 GHz Federal operations. – Radiolocation systems: Includes Dept. of Defense (DoD) ground-based (GB), shipborne (SB), & airborne (AB) surveillance/tracking radars. • High-power surveillance measure targets altitude, range, and bearing at ranges as great as 300 nmiles. • Air Force assisting pilots in formation flying, drop-zone training • Weapon control systems (e.g. data update communications to missiles, gunfire control) in 3400 – 3650 MHz, air defense in 3100 -3650 MHz. – Radionavigation systems: Includes Air Traffic Control (ATC), air marshalling, and short-range air-search radar systems. • Navy ship-borne radars operate in 21 channels throughout this band. • Frequency relocating the above may require new technology and significant redesign. • Radars increasingly operate over larger bandwidths to improve image resolutions as targets grow complex. – NTIA focused on geographic sharing leading to geographically-limited licensing. • Adjacent band radars must be considered as they may pose an interference to the deployment of 3.5 GHz wireless systems. – Potential interference from in-band and adjacent radars might significantly limit how much spectrum is fully usable. Background S- Band Radar Spectrum 3400 Band 42 TDD (3400-3600) Band 43 TDD (3600-3800) 3650 3600 3800 3550 The proposed CBS band 3700
- 4. Spectrum - Shared Operation • Spectrum: scarce, expensive. Government-held spectrum underused1. – Release spectrum to mobile broadband (1675-1710, 1755-1780, 3500-4400 MHz). – Spectrum sharing should avoid incumbent-entrant destructive interference. • Most government operation is radars. Increasingly use larger bandwidths as targets go complex. • Transmit high power pulses to space. Hitting object, pulse radiate omni. Echo reveals detection. • Add spectrum-additive measures to the RRA (use radar spectrum). – How destructive is sharing? Example 3.5 GHz band. • MNOs: all fine! Cellular technologies sustain. • Army: all bad! Exclusion zones from radar-WiMAX link budget reach 577 km. • Excludes more than 55% of US population. • Investment in the band unattractive. – Simulations needed. NTIA Fast Track Evaluation 1NTIA TR-14-500.
- 5. Radar Simulation • Radar parameters in the table are adopted from NTIA’s Fast Track Evaluation. •Radar radiates on LTE at 50, 100, 150, and 200 km away. • 83 dBm without antenna, and 83 + 45 = 128 dBm radiation. •360 deg horizontal scan. • Radar circulates at 30 rotation per minute (rpm). Horizontal scan time becomes 2 s. 360/0.81 = 445 beam positions for the search fence. Antenna dwell time becomes 2/445 = 4.5 ms. PRI = 0.5 ms gives 9 pulses during the dwell time. An BS under radiation is hit by 9 pulses. 4000 pulses (each 83 + 45 dBm) are radiated in a rotation of the antenna. •At distance R radar radiation diameter becomes: 1.5, 3.0, 4.5, 6.0 km radiation diameter when radar is 50, 100, 150, and 200 km away. Parameters Value Operating Frequency 3.5 GHz* Peak Power 83 dBm Antenna Gain 45 dBi Antenna Pattern Cosine Antenna Height 50 m Insertion Loss 2 dB Pulse Repetition Interval 0.5 ms Pulse-Width 78 µs Rotation Speed 30 rpm* Azimuth Beam-Width 0.81 deg* Elevation Beam-Width 0.81 deg* Azimuth Scan 360 deg RRd a 03.0)(tan2
- 6. Radar Simulation •Antenna back-lobe -50 dB vs. the main lobe. •Based on ITU-R M.1851 (mathematical model for radar antenna used in NTIA Fast Track Evaluation). dB G dB e dB dB 50 ) ||33.2 (log51.17 ) ) )sin(8.68 () 2 ( ) )sin(8.68 cos( ( 2 )( 3 2 3 2 3
- 7. LTE Simulation (Macros,Outdoor Small Cells) •Antenna Pattern for Macro LTE BS •3GPP-compliant system-level simulator. •3GPP-defined macro, small-cell and indoor scenarios. •Utilizes proportional-fair scheduler in both time and frequency domains. •Detailed UL air interface modeling, UL MIMO, and receiver diversity. •Non-ideal link adaptation with Hybrid ARQ. •EESM link-to-system mapping. •More precisely modeling Turbo decoder saturation. •Updated SC-OFDMA SINR calculation with radar interference present. •pilot symbols for Base Stations Interference Measurements. 13GPP TR 36.814 V9.0.0 (2010-03), “Further advancements for E-UTRA physical layer aspects”, Release 9. },{},,)(12min{)( 2 3 , EAiAG m dB tii ii }),()((min{ mEEAA AGGG Parameters Value Operating Frequency 3.5 GHz Layout Hexagonal macro cell grid, clustered small cells Mode TDD Macro/Small Cells BS TX Power 46/30 dBm UE Transmit (TX) Power 23 dBm Macro-cell sites/cells 7/21 (3 cells per site) Outdoor Small cells 84 (4 per macro cell) Indoor UE ratio for Macro/Outdoor Small cells 80% / 20% Bandwidth for Macro / Small cells 20 MHz BS Antenna Gain for Macro / Small cells 17/ 5 dBi UE Antenna Gain 0 dBi Macro Inter-site Distance (ISD) for Uma/Umi 500 m Minimum UE-BS Distance for Uma/Umi 25 / 5 m BS Antenna Downtilt for Macro 12 deg BS Antenna for Small Cells Omni-directional BS Antenna Height Uma/Umi/InH 25 ,10 UE Antenna Height 1.5m UE Distribution for Macro / Small cells Uniform/Clustered UE Mobility 3 km/h, uniform direction BS/UE Noise Figure (NF) 5/9 dB Thermal Noise -174 dBm/Hz Service Profile Full buffer best effort UEs per Cell for Macro / Small cells 10 / 30 Channel Model for Macro / Small cells UMa / Umi [1]
- 8. Macro Cells Layout -800 -600 -400 -200 0 200 400 600 800 -800 -600 -400 -200 0 200 400 600 800 Macro Cell Layout Macro Site Positions UE Positions•Macro/Small cell layout for 7 sites. •500 m ISD. m m -800 -600 -400 -200 0 200 400 600 800 -800 -600 -400 -200 0 200 400 600 800 Macro and Small Cell Layout Pico cell UE Macro cell
- 9. • In LoS, FSPL represents the loss radar signal undergoes. • In NLoS region, ITM model represents the loss. Propagation Models (radar-LTE path) LoSFSPLdB rrrfrL ,45.32)log(20)log(20)(, )(1.4 LTEradarLoS hhr Parameters Value Operation Mode Area Prediction Mode Small, Macro cells LTE/Radar Antenna Height 10, 25/50 m Dielectric Constant 15 Conductivity 0.005 S/m Refractivity 301 N-units Climate Continental Temperate Variability Mode Single Message Surface Refractivity 15 Sitting Criteria Random
- 10. • Signal-to-interference-to-noise ratio (SINR) of an LTE macro BS versus LTE symbol and subcarrier indices. Even when radar is present, SINR recovers until next pulse. Radar pulse is centered in the LTE band, so most energy is concentrated around subcarrier 300 (middle of the LTE channel). 78 µs wide pulses exceed the duration of the LTE symbol (71.4 µs). Energy is mostly concentrated in symbols 1 and 8, with some remaining pulse energy also present in symbols 2, 9 and 14. Simulation Results (Macro Cells)
- 11. Radar - LTE SimulationUNCLASSIFIED//FOR OFFICIAL USE ONLY UMa UMi Co-channel Out-of-Band
- 12. Radar - LTE SimulationUNCLASSIFIED//FOR OFFICIAL USE ONLY • The exclusion distances between radars and LTE in NTIA Fast Track Report are overly conservative. • Need to better characterize the propagation characteristics between radars and LTE. • Premature to lock in exclusion zones. • Resource allocation mechanisms should include spectrum sharing methods.
Editor's Notes
- #3: Cellular networks’ demand for more bandwidth from one hand and the scarcity and cost of the spectrum allocated for mobile broadband from the other hand puts forward a capacity challenge for mobile network operators. In response to the request for more bandwidth, overprovisioning is not a long term solution since it uneconomical and smart devices’ traffic intensive apps can easily consume up any additional capacity. However, radio spectrum is underutilized in its certain portions, so leveraging fine-grained resource allocation mechanisms which also use a dynamic spectrum access to the underutilzed portions can be part of a solution to the currently limited bandwidth assigned for mobile broadband. DSA leads to spectrum efficiency and adaptability by leveraging spectrum holes, which makes the spectrum a congested environment. In the realm of DSA, band incumbents still use the spectrum which makes it a contested environment.
- #5: As we mentioned before, a RRA framework should include for spectrum additive measures to be able to respond to the diverse needs of modern cellular system. Even though overprovisioning cannot address the capacity limitation problem of mobile broadband networks due to cost-uneffeciveness, assigning additional spectrum for mobile broadband purposes is a must. This notion is further motivated by severe underutilization of large portions of spectrum used by government and defense. Examples are 1675-1710, 1755-1780, and 3500-4400 MHz bands which was proposed by FCC as potentials for spectrum sharing. Such a proposition for the case of say 3.5 GHz band was harshly opposed by defense saying that cellular system operation is not feasible in the frequency and space vicinity of radars, which emit very strong pulses to the space. NTIA performed some link budget analyses and concluded exclusion zones up to 577 km before any cellular system can be deployed; this will exclude more than 55% of the US population and make investments in the 3.5 GHz band unattractive for MNOs. However, providing exclusion zones can only be valid in the light of precise simulations of the involved technologies as opposed to link budget analyses.
- #12: In this plots, we observe the LTE UL throughput when a cochannel radar is hitting the LTE system at 200, 150, 100, and 50 km away from the LTE. The brown bar represents the baseline, i.e. when no radar is present. On the right hand side, the same plots are illustrated for an out-of-band radar. The plots show that the least effect is for indoor small cells, and LTE sustains without any interference mitigation techniques adopted, and locking the exclusion zones would be premature.
- #13: In this plots, we observe the LTE UL throughput when a cochannel radar is hitting the LTE system at 200, 150, 100, and 50 km away from the LTE. The brown bar represents the baseline, i.e. when no radar is present. On the right hand side, the same plots are illustrated for an out-of-band radar. The plots show that the least effect is for indoor small cells, and LTE sustains without any interference mitigation techniques adopted, and locking the exclusion zones would be premature.