1

1. NTN Overview
& Channel Model
報告日期：2022/3/24
系級：通訊所二
學號：609430026
姓名：翁寬

2. CCU Comm.
Smart Antenna Lab
References
[1] I. Ali, N. Al-Dhahir, and J. Hershey, “Doppler
characterization for LEO satellites,” IEEE
Transactions on Communications, vol. 46, no. 3,
pp. 309-313, Mar. 1998.
[2] I. Ali, N. Al-Dhahir, and J. Hershey, “Predicting
the visibility of LEO satellites,” IEEE
Transactions on Aerospace and Electronic
Systems, vol. 35, no. 4, pp. 1183-1190, Oct.
1999.
2

3. CCU Comm.
Smart Antenna Lab
References
[3] 3GPP TR 38.811 v15.3.0, “Study on New
Radio (NR) to support non-terrestrial
networks (Release 15),” Jul. 2020.
3

4. CCU Comm.
Smart Antenna Lab
Roles for NTN in 5G System
 Foster the rollout of 5G service in un-served
area and upgrade the performance in
underserved area
 Reinforce the 5G service reliability and
ensure service availability
 Enable 5G network scalability
4

5. CCU Comm.
Smart Antenna Lab
5G Use Cases
 eMBB
 Multi-connectivity
 Fixed cell connectivity
 Mobile cell connectivity
 Network resilience
 mMTC
 Wide area IoT service
 Local area IoT service
 URLLC
5

6. CCU Comm.
Smart Antenna Lab
NTN Architecture
 NTN terminal
 VSAT
 3GPP class 3 UE
 Airborne platform
 Non-regenerative
 Regenerative
 Service link
 Inter-satellite/aerial
link
 Feeder link
 Gateway
6
NTN Terminal NTN Gateway
Airborne Platform Airborne Platform
Service Link Inter-satellite/aerial link Feeder Link

7. CCU Comm.
Smart Antenna Lab
NTN Architecture
7
NTN Gateway
Non-regenerative
UE gNB
A1 NGC Data Network
NTN Terminal
(3GPP class 3 UE)
Service Link Feeder Link
NTN Gateway
Regenerative
UE gNB
A2 NGC Data Network
NTN Terminal
(3GPP class 3 UE)
Service Link Feeder Link

8. CCU Comm.
Smart Antenna Lab
NTN Architecture
8
Regenerative
NGC
UE Relay Node
A4 gNB Data Network
NTN Terminal
(VSAT)
Service Link Feeder Link
NTN Gateway
NGC
UE Relay Node
A3 gNB Data Network
NTN Terminal
(VSAT)
Service Link Feeder Link
Non-regenerative NTN Gateway

9. CCU Comm.
Smart Antenna Lab
Airborne Vehicle
 Geostationary satellites (GEO)
 Non-geostationary satellites (NGEO)
 Low Earth orbiting satellite (LEO)
 Medium Earth orbiting satellite (MEO)
 Aerial
9
GEO NGEO Aerial
Altitude (km) 35786 600-1500
/ 7000-20000
8-50
Beam Footprint size
in diameter (km)
200-1000 100-500 5-200

10. 10
D1 D2 D3 D4 D5
Platform Orbit &
Altitude
GEO at
35786 km
GEO at
35786 km
Non-GEO
down to
600 km
Non-GEO
down to
600 km
Airborne vehicle
up to 20 km
Frequency
Band
Ka band
DL: 20 GHz
UL: 30 GHz
S band
DL :2 GHz
UL: 2 GHz
S band
DL: 2 GHz
UL: 2 GHz
Ka band
DL: 20 GHz
UL: 30 GHz
S band
below/above
6 GHz
Beam Pattern Earth fixed
beams
Earth fixed
beams
Moving
beams
Earth fixed
beams
Earth fixed beams
Duplexing FDD FDD FDD FDD FDD
Channel Bandwidth
(DL+UL)
Up to
2*800 MHz
Up to
2*20 MHz
Up to
2*20 MHz
Up to
2*800 MHz
Up to
2*800 MHz in mobile
2*20 MHz in fixed use
NTN Architecture A3 A1 A2 A4 A2
NTN Terminal
Distribution
100%
outdoor
100%
outdoor
100%
outdoor
100%
outdoor
Indoor
& outdoor
NTN
Terminal Speed
Up to
1000 km/hr
Up to
1000 km/hr
Up to
1000 km/hr
Up to
1000 km/hr
Up to
500 km/hr
Main Rationales Indirect
access via
relay node
Direct
access
Direct
access
Indirect
access via
relay node
Direct access
NTN Terminal Type VSAT 3GPP
class 3 UE
3GPP
class 3 UE
VSAT 3GPP class 3 UE
& VSAT

11. CCU Comm.
Smart Antenna Lab
NTN Channel
 Delay
 Propagation delay
 Differential delay
 Line of sight (LoS)
 Doppler shift
 Common part
 Differential part
 Fast fading
11

12. CCU Comm.
Smart Antenna Lab
Propagation Delay
 One way propagation delay
 Two way propagation delay (round trip time)
12
NTN Gateway
Non-regenerative
UE gNB
NTN Gateway
Regenerative
UE gNB NGC

13. CCU Comm.
Smart Antenna Lab
Differential Delay
 The difference of propagation delay
between two point in the footprint.
(i.e. the edge and the center)
13
radius

14. CCU Comm.
Smart Antenna Lab
Doppler Shift
 Caused by the relative motion between
NTN terminal and satellite.
 Includes common part and differential part.
14
_ _
( ) ( ) ( )
d d common d differential
f t f t f t
 

15. 15
M
P
M
N
0
( ) ( )
v
t t
 

( )
v
t

0
( )
t

P
O
y
x
z
S: satellite’s location at
time
S’: satellite’s location
at time when at the
maximum elevation angle
N
M
t
v
t
( )
t

( )
t

( )
t

h
P
N
S
( )
s t
e
R
cos( ( ))
e
R t

sin( ( ))
e
R t


16. CCU Comm.
Smart Antenna Lab
Satellite Visibility Time
16
𝑅𝑒: radius of the Earth
𝑓𝑐: carrier frequency
𝑟: distance from center of the
Earth to the satellite, 𝑟 = 𝑅𝑒 + ℎ
𝜃𝑀𝐴𝑋: maximum elevation angle
𝜃𝑀𝐼𝑁: minimum elevation angle
𝜔𝐹 𝑡 :angular velocity of the satellite
in the ECF
1
1
0
1
cos(cos [ cos( )] )
2
( ) 2 cos ( )
( ) (cos [ cos( )] )
e
MIN MIN
MAX v
e
F
MAX MAX
R
r
t t
R
t cos
r
 
 
  




   

1
0 0
0
cos[ ( )]
( ) ( ) ( ) ( ) cos ( )
cos[ ( )]
v
v v F
t
t t t t t
t

  


   

17. CCU Comm.
Smart Antenna Lab
Common Part
 Assumption
 UE is fixed.
 Angular velocity of the Earth and the satellite
are constant.
 The satellite orbit inclination are not taken into
consideration.
17
(t) cos( )
F s E s
i
   
  
𝜔𝐹 𝑡 : angular velocity of the satellite
in the ECF
𝜔𝑠: angular velocity of the satellite
i: satellite orbit inclination
𝜔𝐸:angular velocity of the Earth

18. CCU Comm.
Smart Antenna Lab
18
Common Part
𝑅𝑒: radius of the Earth
𝑓𝑐: carrier frequency
𝑟: distance from center of the
Earth to the satellite, 𝑟 = 𝑅𝑒 + ℎ
𝜃𝑚𝑎𝑥: maximum elevation angle
𝜔𝐹 𝑡 :angular velocity of the satellite
in the ECF
𝜔𝑠: angular velocity of the satellite
1
( ) cos{cos [ cos( )] }
e
MAX MAX MAX
R
r
   

 
_
0
2 2
0
2 2
( ) ( )
sin[ ( ) ( )] ( ) ( )
2 cos[ ( ) ( )] ( )
sin[ ] ( )
2 cos[ ] ( )
c
d common
c e MAX F
e e MAX
c e F MAX F
e e F MAX
c e
f
f t s t
c
f R r t t t
c R r R r t t
f R r t
c R r R r t
f R r
c
    
   
   
  


 

  


 


2 2
sin[ ] ( )
2 cos[ ] ( )
s MAX s
e e s MAX
t
R r R r t
   
  
 

19. CCU Comm.
Smart Antenna Lab
Differential Doppler Shift
19
D/2
1
3
4
C 2
y
z
x
 Assume that footprints are circle.
D: diameter of the footprint

20. CCU Comm.
Smart Antenna Lab
Differential Doppler Shift
20
 Assumption
 Maximum elevation angle is 90 degree.
 The satellite is moving along y-z plane.
s

x
y
z
e
R
𝑑(𝑡)
𝑅𝑒
ℎ
𝜃(𝑡)
𝑅𝑒
𝜔𝑠𝑡
h: height of the satellite
𝑑 𝑡 : distance vector between the
satellite and UE
𝜃(𝑡): elevation angle
𝜔𝑠: angular velocity of the satellite
𝑅𝑒: radius of the Earth

21. CCU Comm.
Smart Antenna Lab
21
Differential Doppler Shift
h: height of the satellite
𝑑 𝑡 : distance vector between the
satellite and UE
𝜃(𝑡): elevation angle
2 2 2
2 2
( ) sin( ( ))
cos( )
( ) [ ( )cos( ( ))] [ ( ) sin( ( )) ]
= ( ) 2 ( ) sin( ( ))
e
s
e e
e e
R d t t
t
r
R h d t t d t t R
d t R R d t t


 



   
 
2 2
_ 2 2
2
2 2
2
2 2 2
2
sin ( )
( )
2 cos( )
2 2 ( ) sin( ( )) ( ) sin ( ( ))
2 2 ( ) sin( ( ))
( ) ( ) sin ( ( ))
( )
c s e s
d common
e e s
e e
c s e
e e
c s e
f R r t
f t
c R r R r t
R h h R d t t d t t
f R
c R h h R d t t
d t d t t
f R
c d t
 

 





 
 
  


 



cos( ( ))
c s e
f R
t
c




𝑅𝑒
ℎ
𝜃(𝑡)
𝑅𝑒
𝜔𝑠𝑡

22. CCU Comm.
Smart Antenna Lab
Differential Doppler Shift
22
𝛼1(𝑡) 𝛼𝑐(𝑡)
1 c
y
z
2 2
1 1
1 1
( ( ) cos( ( )) ) ( ( ) cos( ( )))
2
( ) cos( ( ) sin( )
c c
s
D
d t t d t t
d t t r t
 
 
 

2 2
1
2 2 2
sin( )
cos( ( ))
2 cos( )
sin( )
2
cos( ( ))
2 cos( ) ( ) sin( )
2
s
c
e e s
s
e e s s
r t
t
R r R r t
D
r t
t
D
R r R r t Dr t





 
 
 


   
_ 1
( ) [cos( ( )) cos( ( ))]
y c s e
d differential c
f R
f t t t
c

 

  

23. CCU Comm.
Smart Antenna Lab
Differential Doppler Shift
23
y
z
x
_ _ , _ , 3
( ) ( , ) ( , )
x
d differential d common MAX c d common MAX user
f t f t f t
 
  
1
, , 3
2
90 , tan ( )
MAX c MAX user
h
D
  
 
1
2 2
2 2 1
2
(tan ( ))
sin( ) 1
( )
2
2 cos( ) 2 cos( ) (tan ( ))
c s e s
e e s
e e s
h
f R r t D
c h
R r R r t R r R r t
D

 
  



 
   

24. CCU Comm.
Smart Antenna Lab
Simulation Results
24

25. CCU Comm.
Smart Antenna Lab
Simulation Results
25

26. CCU Comm.
Smart Antenna Lab
26
Simulation Results
Δ𝑓𝑑
𝑦
𝑡 Δ𝑓𝑑
𝑥
𝑡

27. 27
D1 D2 D3 D4 D5
Platform Orbit &
Altitude
GEO at
35786 km
GEO at
35786 km
Non-GEO
down to
600 km
Non-GEO
down to
600 km
Airborne
vehicle up to
20 km
Frequency
Band
Ka band
DL:20GHz
UL:30GHz
S band
DL:2GHz
UL:2GHz
S band
DL:2GHz
UL:2GHz
Ka band
DL:20GHz
UL:30GHz
S band
below/above
6GHz
Max One Way
Propagation
Delay (ms)
272.37 272.37 14.204 14.204 1.526
Max Differential
Delay (ms)
16 16 4.44 4.44 0.697
Max Doppler
Shift (kHz)
+/- 18.51
@20GHz
+/- 27.76
@30GHz
+/- 1.851 +/- 48 +/- 480
@20GHz
+/- 720
@30GHz
+/- 0.1
@2GHz
Percentage of
Max Doppler
Shift in Carrier
Frequency (‰)
0.001 0.001 0.024 0.024 0.00005
Max Doppler
Variation (kHz/s)
Negligible Negligible 0.544 5.44
@20GHz
8.16
@30GHz
Negligible