Reconstruction of how components communicate with each other during system execution is crucial for debugging system-on-chip designs. However, limited observability is the major obstacle to the efficient and accurate reconstruction in the post-silicon validation stage. This paper addresses that problem by proposing several communication event selection methods guided by system-level communication protocols. Such methods are optimized for on-chip communication event tracing infrastructure to enhance observability. The effectiveness of these methods are demonstrated with experiments on a non-trivial multicore SoC prototype. The results show that with the proposed method, more comprehensive information on system internal execution can be inferred from traces under limited observability.