## 1 Introduction
The focus of this paper was to put forward an intelligent opportunistic routing protocol so that the consumption of resources particularly during communication could be optimized, because the  
Figure 1: Sensor node architecture with application in e-healthcare. alleyway taken to transmit a data packet from a source node to the target node is determined by the routing protocol. Routing is a complex task in WSN because it is different from designing a routing protocol in traditional networks. In WSN, the important concern is to create an energy-efficient routing strategy to route packet from source to destination, because the nodes in the WSN are always energy-constrained. The problem of energy consumption while routing is managed with the use of a special type of routing protocol known as the Opportunistic Routing Protocol. The opportunistic routing (OR) is also known as any path routing that has gained huge importance in the recent years of research in WSN [8]. This protocol exploits the basic feature of wireless networks, i.e., broadcast transmission of data. The earlier routing strategies consider this property of broadcasting as a disadvantage, as it induces interference. The focal notion behind OR is to take the benefit of spreading the behavior of the wireless networks such that broadcast from one node can be listened by numerous nodes. Rather than selecting the next forwarder node in advance, the OR chooses the next forwarder node robustly at the time of data transmission. It was shown that OR gives better performance results than traditional routing. In OR, the best opportunities are searched to transmit the data packets from source to destination [9]. The hop-by-hop communication pattern is used in the OR even when there is no source-to-destination linked route. The OR protocols proposed in recent times by different researchers are still belligerent with concerns pertaining to energy efficiency and the reliable delivery of data packets. The proposed OR routing protocol given in this paper was specifically meant for WSN, by taking into account the problems that surface during the selection of relay candidates and execution of coordination protocol. The proposed protocol intelligently selects the relay candidates from the forwarder list by using a machine learning technique to achieve energy efficiency. The potential relay node selection is a multi-class with multiple feature-based probabilistic problems, where the inherent selection of relay node is dependent upon each node's characteristics. The selection of a node with various characteristics for a node is a supervised multiclass non-linearly separable problem. In this paper, the relay node selection algorithm is given using [PERSON]'s machine learning model. The organization of this paper is as follows. Section 2 presents the related work in the literature regarding OR and protocols. The various types of routing protocols are given in Section 3. Section 4 describes OR with examples, followed by the proposed intelligent OR algorithm for forwarder node selection in Section 5. Section 6 depicts the simulation results of the proposed protocol by showing latency, network lifetime, throughput, and energy efficiency. Section 7 presents a proposed framework for integration IoT with WSN for e-healthcare. This architecture can be useful in many e-healthcare applications. Section 8 presents the conclusion and future.