Coded pilot synchronization in wide band sub-THz communication systems

Sammanfattning

Future wireless communication systems operating in the sub-terahertz (sub-THz)frequency range (100–300 GHz) offer extremely large bandwidths, enabling ultrahigh data rates for next-generation applications such as wireless backhaul, chip-tochip communication, and sensing. However, carrier synchronization (CS) in suchsystems remains a major challenge due to large carrier frequency offsets (CFO), severe phase noise, and the impracticality of using ultra-high-speed analog-to-digitalconverters (ADCs) for wideband signal processing.This thesis proposes a low cost analog-digital hybrid synchronization method using a low-power pseudo-noise (PN) coded pilot that can be detected even at verylow power levels using matched filtering. A PN-coded pilot is embedded within thetransmitted signal (a single wideband signal) at power levels up to 30-50 dB belowthe data signal. At the receiver, the pilot is extracted using a narrowband filterand processed with a PN-based matched filter to achieve significant processing gain,enabling reliable detection using low-speed ADCs.A hybrid analog–digital phase-locked loop (PLL) architecture is proposed, wherecarrier frequency and phase estimates obtained from PN correlation are used tocontrol the local oscillator. The system is first validated through MATLAB simulations under realistic impairments, including large CFO and strong phase noise.Results demonstrate successful carrier recovery and reliable detection of pilot signals buried down to 30 dB below the data signal. The proposed approach is furtherimplemented on an FPGA platform to evaluate real-time performance and hardwarefeasibility.The results show that PN-coded pilot synchronization is a promising solution for enabling practical, low-complexity carrier recovery in ultra-wideband sub-THz systemswithout requiring high-speed data converters.