# Fuzzy Logic-Based Geographic Routing Protocol for Dynamic Wireless Sensor Networks
## 2 Related Studies  
In dynamic wireless sensor networks, the high routing overhead problem, routing void problem, and inaccuracy location problem occur frequently for geographic routing protocols. Hence, the data forwarding mode and location prediction algorithm of geographic routing have become research hotspots. Thus, in this paper, the fuzzy logic-based geographic routing protocol and location-fault-tolerant geographic routing scheme will be introduced.  
A typical geographic routing protocol, greedy perimeter stateless routing (GPSR) is proposed in [7]. The greedy forwarding mode and peripheral forwarding mode are adopted in the GPSR protocol. In the greedy forwarding mode, the neighbor node nearest to the destination node is selected as the next forwarding node. However, the routing void problem occurs in a sparse network. The peripheral forwarding mode can solve this problem, based on planarization and right-hand rules.  
Some improved data-forwarding strategies are also proposed. In Reference [10], a new GPSR protocol based on angle and distance (GPSR-AD) is proposed. In the GPSR-AD protocol, the distance and angle are considered in selecting the next forwarding node, which can effectively reduce the number of routing hops. [PERSON] et al. put forward an improved greedy forwarding strategy based on fuzzy logic control [11]. The new scheme can actively choose the next forwarding node in order to reduce the end-to-end delay, stabilize the queue length, and improve transmitting efficiency. A congestion-aware forwarder selection method for greedy forwarding mode is proposed in Reference [12]. The energy consumption and end-to-end delay can be reduced by combining multiple performance metrics, including energy consumption, forwarding direction, and congestion level of a potential forwarder. To solve the routing failure, [PERSON] and [PERSON] [13] proposed a geographic routing scheme that can provide reliable and efficient routes by computing the range of azimuth angles that it can cover.  
There are many existing studies that explore location prediction-based and location-fault-tolerant geographic routing protocol [14; 15; 16; 17]. Based on the autoregressive integrated moving average (ARIMA) prediction model [18], the optimal path for data transmission can be selected to reduce the routing reconstruction overhead [14; 15]. In Reference [16], [PERSON] proposes an efficient geographic routing scheme based on location prediction and energy saving (LPESGR). Based on the prediction distance of signal transmission, the routing void problem can be solved by a new power real-time adjustment scheme. The LPESGR protocol can effectively reduce network energy consumption and improve the success rate of data transmission. To resolve the location inaccuracies problem, [PERSON] et al. proposed a novel location-fault-tolerant geographic routing (LGR) [17] scheme based on the combination of position-based clustering and geographic routing technologies.  
Although studies on data forwarding strategies and the node location prediction algorithm can reduce the number of hops and the forwarding delay to some extent, existing strategies tend to increase the extra routing overhead to obtain the location information of destination nodes through the location service algorithm. Especially in dynamic wireless sensor networks, the location information of destination nodes should be acquired in a timely and accurate manner, which would inevitably increase the routing overhead.