# A Source Anonymity-Based Lightweight Secure AODV Protocol for Fog-Based MANET
## 2 Related Works
### Improving Transmission Performance  
As a distance vector routing protocol for MANET, AODV protocol permits intermediate nodes to reply, allowing the source node to quickly obtain routing in order to effectively reduce the number of broadcasts. Since nodes only store on-demand routing, this scheme can reduce the memory requirements and unnecessary duplications. However, because of periodically broadcast packets, a certain energy consumption and network bandwidth have to be considered. Due to the existence of stale routing, AODV protocol requires a relatively long latency to establish routes. Currently, the improvements of transmission performance in AODV mainly involve the following aspects: the energy efficiency, reducing the network congestion, improving the throughput, load balancing, and so on. [PERSON] and [PERSON] proposed Resilient AODV (RAODV) protocol [19]. In the route discovery phase, RAODV differed from AODV. RAODV protocol established as many routes as possible, whereas AODV only established one routing path from a source node to the destination node. Thus, when the primary route broke, the node could immediately adopt an alternative route without further route search. If there was no possible alternative route, the node would transmit the route break information backward to instruct the previous node on the reverse route to select an alternative one until an alternative route was found. The RAODV protocol could effectively reduce the number of route rediscovery procedures, the Packet Loss Rate (PLR), and the transmission latency, especially in sparse MANET. [PERSON] et al. presented an optimized protocol, B-AODV [20], to solve the shortage of routing finding and routing repair in AODV protocol. There were two steps in B-AODV. Firstly, \(BRREQ\) (B-AODV \(RREQ\)) was used to replace of \(RREQ\) in order to reduce the time of route finding. Secondly, optimizing the two hops record in control messages and route table could improve the rate of routing repair and reduce the time required to find a route. Additionally, it improves the function of the Ad Hoc network. [PERSON] and [PERSON] introduced an Improved AODV (I-AODV) protocol [21]. In the I-AODV protocol, the location and energy level of the nodes were considered, and the route discovery area was restricted based on the source and destination location. The nodes lying in this region were taken into account as route nodes. One hop communication took place when the two nodes were located in the communicating range of each other. If the communicating nodes were far away each other, then according to the distance between the selected intermediate node and destination node, the energy for the intermediate nodes was greater than the threshold energy, and the intermediate nodes were re-selected. This scheme could increase the lifetime of the path. In addition, [PERSON] et al. evaluated the energy consumption and control response of the AODV protocol in WSANs for building-temperature control [22]. [PERSON] et al. evaluated and contracted the MAC/network/energy performance of MPH, AODV, DSR, and ZTR Routing Protocols in WSN [23]. For addressing the congestion issue in MANET, [PERSON] and [PERSON] analyzed the performance of AODV and GPSR (Greedy Perimeter Stateless Routing) protocols in a VANET in multi-scenarios under different traffic conditions with respect to the Packet Delivery Ratio (PDR) and average End-to-End Delay (E2 ED) [24]. They found that AODV performed better with respect to PDR and GPSR outperformed AODV with respect to E2 ED. Moreover, the performance of both the routing protocols varied from one scenario to another and between traffic types. The performance of both AODV and GPSR was improved by using IEEE 802.11p instead of IEEE 802.11. In improving the throughput, [PERSON] proposed an extended AODV (AODV+) protocol [25], which allowed mobile nodes to communicate using the Internet. The AODV+ protocol had the ability to establish gateways, which support Vehicle-to-Infrastructure (V2I) communication.