Robust Symbol Timing Synchronization for Initial Access under LEO Satellite Channel

Area of Science:

• Satellite Communications Engineering
• Digital Signal Processing
• Telecommunications Systems

Background:

• The Digital Video Broadcasting-Return Channel via Satellite 2nd generation (DVB-RCS2) system is crucial for satellite communication, particularly in Low Earth Orbit (LEO) environments.
• Current symbol timing synchronization schemes, often using Non-Data-Aided (NDA) methods, face accuracy limitations with short packets and significant Doppler shifts during initial access.
• These limitations are prominent in Time Division Multiple Access (TDMA) packet demodulators, impacting User Terminal (UT) to Gateway (GW) communication.

Purpose of the Study:

• To propose a robust symbol timing synchronization scheme specifically for the return link initial access in DVB-RCS2 LEO satellite systems.
• To address the accuracy degradation issues associated with short packet lengths and Doppler errors in conventional synchronization methods.
• To develop an improved algorithm for the Gateway (GW) to enhance the reliability of initial access from User Terminals (UTs).

Main Methods:

• Development of a novel symbol timing synchronization algorithm tailored for the GW in LEO satellite communication.
• Focus on Non-Data-Aided (NDA) approaches to avoid reliance on preamble, pilot, or postamble symbols for fine synchronization.
• Computer simulations were employed to validate the performance and advantages of the proposed algorithm.

Main Results:

• The proposed algorithm demonstrates improved estimation accuracy compared to conventional schemes, particularly for short packets during initial access.
• The novel synchronization method effectively mitigates the impact of large Doppler errors inherent in LEO satellite channels.
• Simulation results confirm the practical advantages and robustness of the developed symbol timing synchronization scheme.

Conclusions:

• The novel symbol timing synchronization algorithm offers a significant improvement for DVB-RCS2 LEO satellite return link initial access.
• The scheme effectively overcomes the limitations of existing methods concerning short packet lengths and Doppler frequency shifts.
• This advancement contributes to more reliable and accurate communication in LEO satellite networks, especially during the critical initial access phase.