# A Smart Collaborative Routing Protocol for Reliable Data Diffusion in IoT Scenarios
## 2 Related Work
### Routing Protocols Based on Hierarchy  
For the routing protocols based on hierarchy, the network is divided into multiple clusters. Each cluster owns a CH node to control the communication of nodes. The data is transmitted to the gateway node through the aggregated convergence, which reduces the communication traffic and saves network energy. [PERSON] and [PERSON] [24] proposed an improved clustering algorithm based on the fuzzy logic, which maximized the life-cycle of the network. An effective CH node selection can drastically reduce energy consumption and extend the network life-cycle. Therefore, the proposed algorithm separated the network into clusters on the basis of energy level, distant from CH and crowdedness. If the scale of the cluster was greater than the threshold value, the cluster was divided into sub-clusters. Then the CH was selected based on the fuzzy logic method. In [25], a novel WSN framework was presented to process the collected sensory data. The authors made use of the Low Energy Adaptive Clustering Hierarchy (LEACH) protocol to improve the performances of the system (i.e., reducing packets quantity and transmission delay). The traffic monitoring, prediction, filtering, compression and decompression were incorporated in the proposed framework. Moreover, the technologies of encryption and decryption were applied in WSN. [PERSON] et al. [26] proposed a four-level clustering hierarchy protocol FL-LEACH based on the three-level protocol (TL-LEACH). A Location based Topology Control (LTC) was used to manage the operation of the active nodes in the sensing field, which minimized the intra term of the expended energy. The proposed protocol had the advantages in reducing required energy of the topology and balancing the energy of nodes. In [27], the authors comprehensively discussed and compared the state-of-the-art successors of LEACH protocol. More than 60 related protocols were analyzed, then divided into single-hop and multi-hop communications. The performances of them were compared based on nine different parameters (energy efficiency, overhead, scalability complexity, and so on). Furthermore, the strong and weak points of each protocol were introduced in detail. [PERSON] and [PERSON] [28] presented an improved multi-hop technique based on LEACH protocol, i.e., IMHT-LEACH protocol. The traditional MHT-LEACH protocol distributed all the CHs into two levels, while the IMHT-LEACH protocol divided the CHs into more levels. The simulation results revealed that the proposed protocol obviated the drawbacks of the MHT-LEACH, prolonged the network life-cycle, improved the stability and increased the throughput in WSN. [PERSON] and [PERSON] [29] systematically discussed the working principle of the LEACH protocol by using Omnet++ simulator. The authors first introduced some related transmission protocols, then the working principle of LEACH protocol (i.e., set-up phase and steady-state phase) was analyzed in detail. This protocol was tested in message flow and energy consumption through Omnet++. The results illustrated that the LEACH protocol optimized the energy consumption. In [30], the authors focused on the hierarchic routing protocols, i.e., CTP (Collect Tree Protocol) and LEACH. Both protocols were generally applied in the SHM (Structural Health Monitoring) system to detect the damages of the civil structures. The performances of CTP and LEACH protocols were analyzed based on the cooja simulator. The results showed that the distance of nodes in both CTP and LEACH could affect the performances of SHM systems. [PERSON] et al. [31] analyzed recent researches in LEACH protocol and various improved routing protocols comprehensively, and had the advantagesand disadvantages of them discussed in detail. The evaluation of various LEACH protocols was given in the forms of clustering, aggregation of data, type of mobility and type of scalability. In [32], a novel routing protocol was presented in WSN by combing the LEACH protocol and a heuristic method, which lowered the energy consumption.