Abstract: For the coverage enhancement problem in the scenario of direct-to-satellite service, this paper gives solutions from limited link aspect and wide coverage aspect, studying a series of key technologies including signal repetition transmission, multi-slot joint channel estimation, reference signal power increasing, high gain antenna, beam splitting, beam hopping, power allocation and service-based dynamic resource allocation. For each key technology, this paper analyzes from following three aspects: theoretical analysis, performance evaluation, impact on specification and optimization ideas. Studies show that repeated transmission can directly and effectively improve the link budget performance, but for time-domain resource-constrained scenarios, multi-slot joint channel estimation technology and reference signal power enhancement can provide limited link budget gain. System-level coverage enhancement relies on the beam management to flexibly schedule on-board resources from multiple dimensions to achieve wide-area coverage enhancement.