A method for wireless communication at a user equipment (UE) and related apparatus are provided. In the method, the UE transmits, to a network entity, a buffer status reporting (BSR) in response to a BSR triggering condition from multiple BSR triggering conditions being met. Each of the multiple BSR triggering conditions is associated with a Protocol Data Unit (PDU) set including a group of PDUs. The UE further communicates with the network entity based on the BSR. The method provides multiple BSR triggering conditions based on various scenarios in data transmission. It allows the BSR information to be readily available to the network and enables an efficient resource allocation.