1 Introduction
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An airborne communication network is proposed consisting of OTFS modulation, MIMO systems, and directed links between mobile nodes to jointly cope with the high Doppler shifts induced by extreme relative speeds of above 1200 m/s (4320 km/h).
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A comprehensive performance assessment of OTFS modulation in a high Doppler airborne communication network is conducted in terms of BER.
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The impact of physical layer parameters such as carrier frequency, Mach number, and bandwidth; the role of the number of delay-Doppler bins used for OTFS modulation; the effect of the channel environment; and the benefits of MIMO systems on the performance is revealed.
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The simulation results illustrate that OTFS modulation may not only be considered as a promising technique for high Doppler scenarios in LTE-based 5G and B5G terrestrial broadcasting networks but also for very high mobility scenarios including UAVs, airborne based network components, and satellites.
2 Related work
3 High doppler airborne communication network
4 OTFS modulation
4.1 OTFS Transmitter
4.2 OTFS receiver
5 System model
5.1 Transmitter and receiver processing chains
5.2 Two-Ray model
5.3 Delay-doppler and time-frequency grids
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Time and frequency sampling intervalswhere \(B=M{\varDelta } f\) is the bandwidth.$$\begin{aligned} T = \frac{1}{{\varDelta } f}&\text \;{and}&{\varDelta } f = \frac{B}{M} \end{aligned}$$(14)
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Delay and Doppler sampling intervalswhere \({\varDelta } \tau\) denotes the delay resolution, \({\varDelta } \nu\) is the Doppler resolution, and NT is the packet duration comprising of N symbols of duration T.$$\begin{aligned} {\varDelta } \tau = \frac{1}{M{\varDelta } f}&\text { and }&{\varDelta } \nu = \frac{1}{NT} = \frac{{\varDelta } f}{N} \end{aligned}$$(15)
6 Numerical results
Physical Layer | ||
Carrier frequency |
\(f_c\)
| 13 GHz, 18 GHz |
Mach number |
\(\mathcal {M}\)
| 0.5, 0.75, 1, 1.25, 1.5, 2, 3, 4 |
Bandwidth |
B
| 1 MHz, 5 MHz |
Modulation | Type | 4QAM |
Number of Delay-Doppler Bins Used for OTFS Modulation | ||
Delay bins |
M
| 4, 8, 16, 32 |
Doppler bins |
N
| 4, 8, 16, 32 |
MIMO-OTFS | ||
MIMO |
\(N_T\times N_R\)
| \(1\times 2\), \(2\times 1\), \(2\times 2\) |
\(1\times 3\), \(3\times 1\), \(3\times 3\) | ||
Channel | ||
Two-ray model | Path 1 | Relative delay (\(\mu s\)): 0 |
Relative power (dB): 0 | ||
Path 2 | Relative delay (\(\mu s\)): 2, 6 | |
Relative power (dB): \(-3\), \(-6\) | ||
Angle of arrival \(\theta\): 15\(^{\circ }\), 45\(^{\circ }\) |