## 2 Literature Survey  
The multi-tier WBAN architecture had introduced many challenges in allocating the frequency, including the time required for calculating and allocating frequency. CR when combined with WBAN in a hospital environment has a large potential to solve the channel interference and spectrum insufficiency problem during allocation to the MDs. This work discusses some of the alternative implementations of CR in allocating the spectrum to the OP-BNC over a hospital environment during increased BNC users and provides a better solution for the dynamic channel allocation. In the channel allocation work, [8] proposed how CR is more efficient and safely used in the transmission of a WBAN signal. Figure 3: WBAN and Ultra-Wide Band (UWB) Spectrum. A Multiband Orthogonal Frequency-Division Multiplexing (MB-OFDM) UWB for communication with the OP-BNC is considered as a more efficient spectrum allocation method, but they have not proposed any idea for CR in the Data link layer. The work [10] explored the usage of CR over the existing various types of communication frequency and proved that the existing bands are not the most efficient of the CR through its results. The work [11] proposed an energy-efficient WBAN system for channel selection in CR, where a Particle Swarm Optimization algorithm is proposed in the channel selection. In this model, they had improved the model and increased the lifetime of the system in Tier-2 communication. The model had not proposed any particular on the routing protocol. The disadvantages in the models in the literature outlined above motivated our proposed EFOP algorithm. In the work proposed by [12], the global routing protocol that uses the Dijkstra algorithm is applied in WBAN. In this design, balancing the energy consumption across the network substantially increased the network lifetime of the devices. This also increases the energy per bit transmitter by the system. The network maintenance is reduced, and as a balanced energy consumption mode is used, all the batteries are served at the same time at less frequent times. The result of the proposed model is an average increase in network lifetime of up to 40% and an average increase of 0.4 db in energy per bit. In the proposed work, no reference work on global routing in WBAN is proposed with any reference in the parameter settings, and also, there is not much discussion on the latency. Other than this, the proposed work adds value to the WBAN working environment. Another work proposed [13] an optimal design for WBAN with a data routing and relay positioning problem to increase the network lifetime. The author combined a linear programming model and an energy-aware WBAN model that minimized the energy consumed and installation cost. The work also discussed both cost and energy issues, producing a novel effective model. This model is based on relay nodes, optimal relay nodes, and optimal traffic routing. This work has a combination of two models, and it is a novel approach solution for energy saving. It is a relatively good working model with all its parameter settings. In the proposed work [14], the author proposed an original optimization algorithm that exploits linear relations to guide randomized variables that are implemented in real time. It had been deployed with 30 nodes and operated with a minimum distance of 0.3 m with calculation of its path loss. The system is made to run at various data rates, and the output is measured from it. The proposed work also addressed the traffic uncertainty in the design of WBAN with a single path routing. It is a fast solution algorithm with better quality and lower gaps. This model utilizes the Ant Colony Optimization (ACO), which is a metaheurestic inspired algorithm for the improvement in the energy efficiency of the system. Through the implementation of the ACO in the proposed model, a faster process is also obtained in the given process. A software agent-based disease analysis and machine learning-based data analysis are implemented.