Propose a clustering-based routing protocol for mobility assistant（ CMA） wireless sensor networks（ WSNs）. Moving radius of the mobile sink is determined by application delay requirements and energy consumption in initial phase of networks

and the network is clustered according to certain sink motion trail. Select a number of common nodes as the Rendezvous point（ RP） within communication range of sink

finally sink gathers cache data of the RP node as well as clusters head within its one-hop range. Simulation results show that compared with several existing routing protocols

CMA effectively prolongs network lifetime in the condition of meeting delay requirements.