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Proposed Content of TSB 88.4
Section 7.2 Air-Ground-Air System
Modeling
Motorola Solutions – Sam Makhlouf
3/24/2015
Air-Ground-Air (AGA) Coverage
Modeling
AGA coverage modeling can be handled similarly to terrestrial coverage, but we will
recommend that some key differences should be considered
• Propagation models
– Airborne propagation models are needed for air-to-ground links
– These models typically assume essentially free-space path-loss but also capture effects due to
the curvature of the earth as distance increases (and a function of altitude)
– Since propagation to airborne devices is close to free-space, these devices “see” many sites
(interferers)
– Example airborne propagation model is ITU-R P.528-3
•
Antenna models (base station and device side)
– 3D models, already recommended in terrestrial coverage modeling, are especially important
for AGA
– Base station antenna orientation, for example tilted upward, should be modeled
– Beam-forming at the base station and/or device may also be considered and corresponding
link gains should be modeled
•
Link performance models
– Impact of AGA channels (due to, e.g. Doppler frequency) on link performance should be
modeled appropriately
– Includes impact on, e.g. random access, synchronization, control, and data physical channels
Air-Ground-Air (AGA) Coverage
Modeling (2)
Additional AGA considerations:
• The line-of-sight propagation typical of AGA makes high frequency bands
well suited for AGA
– Poorer propagation characteristics may actually be beneficial to mitigate
interference from distant sites
• TDD is well-suited for AGA as beam-forming works well with TDD (due to
UL/DL channel reciprocity)
• While AGA support can be deployed in the same spectrum as a terrestrial
system, dedicated AGA spectrum is highly recommended
– Same-spectrum deployment has technical challenges and compromised
performance
– See 3GPP RP-150506 “3GPP TSG RAN views regarding Mission Critical Air
Ground Air Communications” and CEPT ECC Report 214 “Broadband Direct-Airto-Ground Communications (DA2GC)”
• Interference-mitigation and suppression techniques are more important
and impactful for AGA performance and may be needed to meet system
performance criteria (whether deployed in dedicated or shared spectrum)