# A Survey of Routing Protocols in WBAN for Healthcare Applications
## 4 Prospects for WBAN and Suggestions for Routing Design
### Prospects for Future Routing Design  
In the future routing design, we can put aside the existing methods to explore and innovate in new areas. In essence, WBAN is a special application of WSN and also a branch of WSN, so it is natural to learn from the relevant energy efficiency technology of WSN, and then optimize and innovate, according to the particularity of WBAN. Since the development of WSN, there are many energy efficiency routing designs and the technologies are mature and perfect. Learning from the relevant technologies in WSN can greatly promote the rapid development of WBAN. For the energy efficiency routing design, we can draw on following methods and ideas. * Cluster-based approach: At present, there are many technologies about energy efficiency design in WSN, and the cluster-based routing is the hottest research. This method is no longer restricted to the improvement of traditional methods, but integrates various intelligent theories and algorithms. For example, [PERSON] et al. [43] proposed a hybrid routing algorithm, which combines ANT colony optimization algorithm and minimum hop routing, to find the optimal path, with the minimum energy consumption and the fastest speed. This method not only improves the ANT colony algorithm, but also optimizes and innovates the minimum hop routing, and it has a great improvement in energy efficiency and delay. [PERSON] et al. [44] proposed an efficient routing algorithm, the process of CH selection is formulated as a single-objective optimization problem to find optimal set of CHs to form, one-hop clusters, in order to balance energy consumption, enhance stability, and scalability, using gravitational search algorithm (GSA). This protocol solved the problem of energy hole, coverage hole, and balanced the network energy consumption. In addition to the above methods, there are many other similar intelligent methods [45; 46; 47; 48; 49], such as distributed artificial ANT colony algorithm, circular random firefly algorithm, particle swarm optimization algorithm, and so on. However, at present, the intelligent methods in WBAN is limited [50; 51; 52; 53; 54], and there is a lot of space for research in the future. We cannot copy the method of WSN completely, but should consider the Qos requirement of WBAN and improve it properly. In routing design, we should also consider the minimum hops, the lowest delay, the temperature of the nodes, and the movement of the limbs. Only suitable for WBAN is the real reference. * Data aggregation method: It is also an energy efficiency design from the source. Data aggregation can effectively reduce redundant data transmission and node energy consumption, and improve the energy utilization of nodes. Although there is no large-scale research on data aggregation technology for WBAN, data aggregation method is a really good way to save energy. Therefore, we can reference the data aggregation method from WSN [55; 56], which need more scholars to study and explore in the future. * Mobile sink-based routing. In recent years, the use of mobile sink has drawn enormous attention for data collection in WSNs, so there are many relevant research studies on this area [57; 58; 59; 60]. For example, [PERSON] et al. [59] proposed a mobile sink (MS)-based inter- and intra-cluster routing algorithms, which is a routing strategy specially designed for the problem of energy hole and coverage hole. The algorithm controls the sojourn position and stay time of mobile sink, effectively solving the above two problems. [PERSON] et al. [60] proposed a dynamic path planning, based on mobile sink for emergency traffic, this protocol considers the priority of data, as well as the emergency traffic perception and estimation, to dynamically adjust the routing and ensure the reliability of data transmission. Therefore, the application of mobile sink in WSN indeed solves many bottleneck problems, such as \"energy hole\" and \"coverage hole\".