Power Control for Commercial Satellites Using Radar Data March 1-3, 2005 Russell Fang March 1-3, 2005 GSAW2005 rf-1
Purpose of Power Control Compensate for up- and down- link margin losses due to rain fades, particularly at Kaand/or Ku- band Minimize the required total aggregate satellite RF power (EIRP) to achieve the downlink availability for terminals in each beam, by dynamically distributing satellite EIRP in response to changes of weather condition in each beam Mitigate impairments caused by co-channel, cross-pol, and adjacent channel interference in a multi-beam Ka-/Ku- band system March 1-3, 2005 GSAW2005 rf-2
Downlink Power Control March 1-3, 2005 GSAW2005 rf-3
Downlink Power Control Concept Weather Radar Vendor Satellite NEXRAD Data Payload Parameter Adjustment Beacon & Traffic Signals Atmosphere NOCC Radar & Beacon Hybrid Algorithm ST Reports NOCC Messages ST Estimate Link Compare to Thresholds March 1-3, 2005 GSAW2005 rf-4
Signal Quality Downlink Channel Condition as a Function of Time Time T max Cell power increase Cell power decrease T min Channel is degrading Channel is improving : response time, a function of round trip propagation delay and processing time March 1-3, 2005 GSAW2005 rf-5
Hybrid Downlink Power Control Radar Vendors NOC DLPC Beacon Measurement ST n 1 ST ST Beacon Algorithm ST n 2 ST ST Beacon Algorithm Radar Data Radar Prediction Beacon Prediction Beacon Prediction Hybrid Algorithm No Data Clear Sky At Risk In No Data Old or Default Value Clear Sky At Risk In Radar Prediction Clear At Sky Risk Clear Sky Clear Sky Clear Sky Clear Sky At Risk At Risk At Risk At Risk In In In In In Payload Parameters Change ST n k ST ST Beacon Algorithm March 1-3, 2005 GSAW2005 rf-6
Radar Pixel Classification Rules WeatherState ( MG ) n : Clear Sky, At Risk,, dbz ( MG ) 15 dbz dbz n ( MG ) < 15 ( MG ) n n 20 < 20 March 1-3, 2005 GSAW2005 rf-7
Cell Weather Classification Rules If (ClearSky)% > (100% - (AreaThreshold)%) Clear Else If ()% > (AreaThreshold)% Else If ( ()% + (AtRisk)% ) > (AreaThreshold)% ) & ( ()% + (NoData)% < (AreaThreshold)% ) At Risk Otherwise Insufficient Data March 1-3, 2005 GSAW2005 rf-8
10 2 CONUS Statistics For a 15 dbz AtRisk Threshold, 20 dbz Threshold, and a 4% Spatial Threshold Confidence Level 50% 84.1% % of time that %CONUS Exceeds weather condition 10 1 10 0 10-1 10-2 AtRis k 97.7% Ra in + AtRis k 99.87% 10-3 0 5 10 15 20 25 30 35 40 % of CONUS Microce lls in We a the r Condition March 1-3, 2005 GSAW2005 rf-9
A Snapshot of Classified CONUS Weather Classified Weather at Each PSA Classified Weather at Each Cell E levation, deg 2 1 0-1 Clear Sky At-Ris k Elevation, deg 2 1 0-1 -2-2 Clear Sky At-Ris k -4-3 -2-1 0 1 2 3 4 5 Azimuth, deg -4-3 -2-1 0 1 2 3 4 5 Azimuth, deg March 1-3, 2005 GSAW2005 rf-10
CONUS Weather Map & Desired Directivity Profile Weather Map Desired Directivity Profile 40 2 P S A Dire c tivity, db 35 30 Elevation, deg 1 0-1 25 2 1 0 Elevation, deg -1-2 -4-2 0 2 Azimuth, deg 4-2 Clear Sky At-Ris k -4-3 -2-1 0 1 2 3 4 5 Azimuth, deg March 1-3, 2005 GSAW2005 rf-11
Resultant Downlink EIRP Plots for a CONUS Shaped Beam 3-D View Top View 2 60 1 EIRP, dbw 50 40 30 Elevation, deg 0-1 20 2 1 0 Elevation, deg -1-2 -4-2 0 2 Azimuth, deg 4-2 -4-3 -2-1 0 1 2 3 4 5 Azimuth, deg March 1-3, 2005 GSAW2005 rf-12
Pencil Beam DLPC Simulation March 1-3, 2005 GSAW2005 rf-13
ST Simulation Model Interference, C / I Pointing Error SINR Measurement Error Beacon EIRP Variation SINR Computation SINR Measurement 0.5 db Gaseous Attenuation Short-Term Filter Downlink Fade Noise Floor Change SINR Linearizer Downlink Channel ST Long-Term Filter BDLPC Algorithm March 1-3, 2005 GSAW2005 rf-14 Delta SNR
Radar & Beacon DLPC Simulation Results (1) Year : 2002, Microcell : 263, Clusters : 1000, STs / Cluster : 1 March 1-3, 2005 GSAW2005 rf-15
Radar & Beacon DLPC Simulation Results (2) Year : 2002, Microcell : 263, Clusters : 1000, STs / Cluster : 1 March 1-3, 2005 GSAW2005 rf-16
Uplink Power Control March 1-3, 2005 GSAW2005 rf-17
ULPC - Objective Set ST s uplink transmit power above the noise and interference level to achieve the target PLR, without overpowering other (faded) STs, in an environment where The downlink (D/L) fade cannot perfectly predict the uplink (U/L) fade. The ST transmitter power varies with frequency and from unit to unit. The interference may vary much more rapidly than the round trip control loop delay. The satellite antenna C/N varies with time. The downlink beacon C/N varies with time. March 1-3, 2005 GSAW2005 rf-18
ULPC Simulation Environment (1) Antenna Patterns ULPC Status Packets U/L Transmit Statistics Collection Weather Model Traffic Generator ST Model March 1-3, 2005 GSAW2005 rf-19
ULPC Simulation Environment (2) All STs assumed to be operated in 512K mode only The following parameters are modeled ST transmit chain (PA, power setting error, pointing error, etc). Beacon variation, beacon measurement error and beacon noise floor variation Satellite received C/N variation and C/N measurement error ULPC status packet loss and delays and RS failures External interference Assumed traffic model Severe CONUS weather mix with clear-sky/mix/rain condition ratio of 50/25/25% March 1-3, 2005 GSAW2005 rf-20
Ring Definition of UL Cells March 1-3, 2005 GSAW2005 rf-21
Mean PLR versus U/L Fade PLR threshold = 10-5 March 1-3, 2005 GSAW2005 rf-22
Concluding Remarks The hybrid radar- and beacon- mode DLPC offers a reliable means to dynamically deliver satellite power to users in accordance to weather condition Radar- mode DLPC method can be readily applied to some bent-pipe satellites for oneway broadcast transmission Beacon- based closed- loop ULPC can be effectively used not only to compensate for UL fades, but also to mitigate the effects of CCI, XPI and ACI. This method can be readily adapted for VSAT applications as well. March 1-3, 2005 GSAW2005 rf-23