# Energy Storage Overflow-Aware Data Delivery Scheme for Energy Harvesting Wireless Sensor Networks
## 2 Related Work  
In EH-WSNs, the nodes scavenge energy from ambient energy sources, such as solar, thermal, wind, vibration [1], or radio frequency [2; 3] sources. With advances in energy-harvesting techniques, it becomes feasible to build a sustainable EH-WSN capable of harvesting energy from the environment to support long-term applications [4]. To describe the EH-WSN applications effectively in simulation environment, SensEH [5] is presented to provide a unified framework that fills the gap between simulation and deployment in the EH-WSN.  
As in any network, data delivery is the key task in the EH-WSN. An optimal data-gathering algorithm for dynamic sensing and routing (DoSR) was proposed [6] to jointly optimize data sensing and data transmission while guaranteeing fairness for the EH-WSN. The routing algorithm with competitive ratio was proposed in [7], which involves the factors of energy consumption, available energy, and energy harvesting rate. The opportunistic routing mechanism was presented in [8] deals with unpredictable duty cycle and wireless channel unreliability by using wireless broadcast nature. The epidemic routing mechanism was applied in the EH-WSN to address the uncertainty of sensors' availability and dynamic network topology [9]. A mobile collector was applied to collect data from designated sensors and balance energy consumption in a solar-powered network [10]. A mobile sink was adopted to improve data collection rate [11]. A fair and high throughput data collection scheme was proposed for the EH-WSN [12], which computes the optimal lexicographic rate assignment under the constraint of no node running out of energy. To support multihop data gathering in the EH-WSN, relay node placement algorithms were proposed [13], which consider network connectivity and survivability. A coding scheme was applied in gathering data for a multihop EH-WSN [14]. The energy-harvesting-aware routing algorithm (EHARA) [15] is proposed to improve the lifetime of sensor nodes as well as the quality-of-service (QoS) under variable energy availability conditions. The online algorithm called optimal scheduling algorithm (OSCAR) proposed in [16] makes decisions on system state, energy harvesting, and data transmission with mobile energy harvested sensing devices so as to achieve close-to-optimal transmission utility performance. The FDEHSN protocol presented in [17] considered the application that the source forwards data to the destination via an energy-harvesting two-antenna relay node. The scenario of an energy-harvesting transmitter sending messages to two users over parallel and fading Gaussian broadcast channels was studied in [18]. As a viable solution to saving energy, compressive sensing is used in [19], which can improve the lifetime of the device in WSNs. The above surveyed data schemes share the same shortcoming that they do not take ESO into account. There are a few data delivery schemes that consider ESO. Route selection schemes that consider network energy wastage due to overcharge of finite-capacity batterieswere proposed in [20] and [21], in which the cost associated with the packet transmission energy consumption and the energy wastage due to battery overcharge is minimized [20] and the wastage due to overcharging of a finite battery is predicted [21]. Although these schemes take ESO into account, they exhibit the problem of uneven energy consumption because they let the source node deliver all data to the destination over a predetermined route. This causes the nodes participating in data delivery to consume much more energy than those not participating in data delivery. The uneven energy consumption problem is considerably alleviated in the proposed EAMP because multiple disjoint paths are used in delivering packets, which differs from the existing ESO-aware data delivery schemes.