1. MCA
ECC PT1
Meeting

2. Antenna Base station antenna down tilt
Preconditions are defined in ECC Report 093 (2008/05) in chapter 6.4 Terrestrial antennas assumed in the studies
Chapter describes the Down Tilt Angle = 0 degrees for MCL (Minimum Coupling Loss) calculations for scenario 1 and 2
Chapter describes the Down Tilt Angle = 2 degrees for SEAMCAT calculations
Base station horizontal antenna pattern
For MCL and SEAMCAT calculations a three sector cell with uniform gain in the horizontal plane is used (equals omni-directional within opening angle of 120 degrees in horizontal plane)
Feeder Loss
Defined in the ECC reports 187 as well
Newer BTS/NodeB/eNodeB use more often “Remote Radio Heads” where the feeder loss is ~0dB (especially at higher frequency bands)
Body Loss
Description of “Human body shielding effect“ is done in chapter of ECC Report 093 with application on the interference scenarios

3. Antenna 2 Preconditions of antenna parameters
ECC Report 093 (2008/05) based on ITU-R F (2000/05) antenna radiation pattern
ECC Report 187 (2013/01) based on ITU-R F (2012/03) antenna radiation pattern
Latest recommended antenna radiation pattern ITU-R F (2014/02) with refining more real antenna pattern (especially side lobes)
The 3dB beamwidth in the elevation plane is derived with the same formula (for ITU-R F.1336 – 1, -3 and -4) in case of involving sectoral antennas with a 3dB beamwidth less than about 120° in both the azimuth plane and the elevation plane!
Application of three 120° sectoral antennas as in ECC report 093 is still valid but not the absolut worst case!
Typical antennas used in ITU BS have a 3dB beamwidth of 90° or 65° in azimuth plane => the 3dB beamwidth in elevation gets higher (main lobe is greater) and therefore the antenna gain for the sidlobes increases too!
Worsening parameters NOT taken into account
Worst case angle calculation for MCL based on ITU-R F leads to higher antenna gain at worst case angle and therefore to higher margin in the link budget calculation
Reflections on the ground plane are not takin into account anyway
Typical antennas with 3dB beamwidth of 90° or 65° in azimuth plane

4. Real Network Handover Statistics Aircraft-based

5. Additional Topics User can use manual network search
E.g. Users in border regions have manual mode permanently switched on.
User may disable roaming

6. Interference - 1
Differences between the onboard UE and UE at the ground
Moves with very high speed
Doppler Shift
Network algorithms are designed for ground UE -> Timing advance and equalization
High above the surface -> LOS to cells in a big area
Can receive cells in huge distances

7. Interference – 2 Additional load to the ground network
Same signalling protocols as for UE at ground
Handover
Cell reselection / tracking area update
Random Access Channel and MME affected
Difference is the speed of the aircraft
Every onboard UE will perform HO every 10s -> or cell reselection for data users
Frequent Tracking Area Updates for idle mode UE

8. Interference – 3 Additional load to the ground network
Random Access Procedure
Adjacent cells use different Acess Preamble sets
Onboard UE is received by distant ground eNB
Some of them would have the same AP set
RACH has no destination address, only AP number
Phantom RACH
eNB answers all RACH in its AP set range
One RACH request is answered by dozens of eNB

9. Interference – 4
Interference to the cell where the onboard UE is connected
Inter Carrier Interference (ICI)
Doppler Shift
Frequency offset creates interference to adjacent ressource blocks
Inter SymbolInterference (ISI)
Timing advance of the ground cell is designed for ground UE
Due to the high speed of the aircraft theTA of onboard UE doesn‘t follow the rapid change in distance

10. Interference – 5 Interference to the other cells
Interference avoidance by
Different frequencies in adjacent cells (GSM)
Different scrambling code in adjacent cells (UMTS)
Far away cells
Can have the same frequency / scrambling code
Interference to other connections

11. Interference – 6 Interference canellation (IC) in uplink
IC detects one or more strong interferers
Known Reference Symbols (RS)
Subtracts the detected interferer from the signal
RS needs to be different in adjacent cells for IC
Far away cells
Could have the same RS
IC can‘t detect these interferers
Doppler shift
Generates some noise to the RS
IC detects wrong channel for the interferer
IC subtracts wrong signal (could even make things worse)

12. Timer HPPLMN Timer HPPLMN Re-Connect to Home Network
Examples: O2-DE: 6min, Vodafone-DE: 30min
Differentiated SIM/UE world
Only configurable via HomeNetwork