CmWave and Sub-THz: Key Radio Enablers and Complementary Spectrum for 6G

Sixth-generation (6G) networks are poised to revolutionize communication by exploring alternative spectrum options, aiming to capitalize on strengths while mitigating limitations in current fifth-generation (5G) spectrum. This paper explores the potential opportunities and emerging trends for cmWave and sub-THz spectra as key radio enablers. We pose and answer three key questions regarding motivation of additional spectrum to explore the strategic implementation and benefits of cmWave and sub-THz spectra. We also show using case studies how these complementary spectrum bands will enable new applications in 6G, such as integrated sensing and communication (ISAC), holographic surfaces and space-air-ground integrated networks. Numerical simulations reveal that the ISAC performance of cmWave and sub-THz spectra outperforms that of existing 5G spectrum, including sub-6 GHz and mmWave. Additionally, we discuss the importance of these complementary bands over conventional bands to enable extended ultra reliable and low-latency communications with better rate-latency-reliability trade-off. Finally, ongoing standardization endeavours, challenges and promising directions are elucidated for these complementary spectrum bands.