Hardware-Efficient Joint Blind Clock Recovery and CMA Equalization for Sub-THz Communications

This paper presents a joint clock recovery (CR) andequalization architecture for high-speed sub-terahertz (sub-THz)wireless links, combining theoretical analysis and experimentalvalidation. The proposed Baud-spaced digital receiver integratesa constant modulus algorithm (CMA) equalizer with a blindtiming error detector (TED) derived directly from the CMAimpulse response, enabling reliable symbol timing synchronization without decision-directed feedback or pilot symbols. Atheoretical interpretation is provided, showing that the proposedTED is related to the minimization of timing-induced intersymbol interference (ISI) and can be viewed as a gradient-basedcorrection embedded within the CMA adaptation. The stabilityand convergence behavior of the coupled CR–equalization loopare discussed, highlighting the trade-off between adaptationspeed and residual timing jitter. Experimental validation isconducted over a 140 GHz wireless testbed using 16-QAMmodulation across a 10 GHz bandwidth. Results demonstrateimproved bit error rate (BER), error vector magnitude (EVM),and residual ISI suppression compared to conventional blindTEDs, including Gardner and blind Mueller & Muller schemes, ¨while maintaining low computational complexity. The proposedarchitecture is particularly pertinent for next-generation spaceborne communication systems, in which wideband sub-THz linksare anticipated to be crucial for supporting ultra-high-data-rateinter-satellite and deep-space communications, despite stringentsynchronization constraints.