In this paper, we have examined various routing protocol of wireless body area network (WBAN), and find out the optimum protocol for its domain. The comparison of different routing protocols has been done on various performance measuring metrics and parameters. And we have also improved existing routing protocol with help of different parameter. During the last few decades, Wireless Body Area Networks (WBAN) have appeared into many applications such as medical, military, sports, entertainments, traversing and monitoring. Due to improvement in wireless technology small sensor nodes with less power, lightweight, interfering or non-interfering are deployed in, on or around the human body to monitor the health situation. Basically, WBAN work on three different Tier Architecture. Tier-1 as Intra-body Communication, and also called sensor nodes. Tier-2 as Inter-WBAN or Internet. Tier-3 as Extra-Body Area Network and also called the servers communication. In this each server like medical server communicate with in its own domain. Routing protocols play very significant role to improve the overall performance of the network in terms of throughput, path loss, residual energy, packet dropped, network lifetime and to improve the different quality of services (QoS) in WBAN. Routing in WBAN is categorized as Postural based, Temperature aware, Cross layer network-based, Clusters-based routing, QoSbasedrouting. These categories are further divided into various protocols. This paper also a review of some of the existing routing protocols of WBAN. Also, the comparison of SIMPLE (Stable Increased-throughput Multi-hop Protocol for Link Efficiency) and IEE-SIMPLE (Improved Energy Efficient-Stable Increased-throughput Multi-hop Protocol for Link Efficiency) protocol has been done by simulating in MATLAB.