||In a wireless sensor network (WSN), nodes transmit their sensing data to the remote sink via single-hop or multi-hop communications. Therefore, the sensors close to the sink consume more energy, because they are responsible for forwarding data from other nodes. Therefore, energy consumption of sensors is not uniform, and there will exist energy holes in the network. Recently, many research effort show that using a mobile data collector can efficiently deal with the energy hole problem and extend network lifetime. How to efficiently schedule the traveling path of the mobile data collector is NP-hard and significantly affects system performance. This problem thus attracts research attention. However, existing schemes usually assume that each sensor generates the same amount of sensing data, and there is no limitation on the buffer size. These assumptions are not practical. When they become invalid, existing schemes may force some sensors to drop packets due to buffer overflow.|
Based on the above consideration, this paper proposes two path scheduling methods for the mobile data collectors, called rendezvous planning for reliable data gathering algorithm (RP-RDGA) and rendezvous planning for reliable data gathering with tour improvement algorithm (RP-RDGTIA). RP-RDGA selects a subset of sensors to be rendezvous point(RPs). Non-RP sensors forward their data to nearby RPs and the mobile data collector will visit each RP to gather data. The selection of RPs considers not only the amount of energy consumed by sensors due to multi-hop communications, but also the buffer capacity of RPs. In this way, we can extend network lifetime and prevent RPs form dropping packets, On the other hand, RP-RDGTIA further improves RP-RDGA by shortening the traveling path. Through simulation, we demonstrate that our proposed algorithms incur almost no packet loss at RPs, and has much less computation overhead than other methods.