Networks, and its full potential is still a long way to reach. Network operators and manufacturers are preparing to release new 5G end-users services and products. Each service must be performant to meet the need of users. Network Slicing (NS) is now one of the most popular 5G technologies in the research community. For network softwarization, Network Slicing affords flexibility and scalability with embedded Quality of Experience (QoE) and Quality of Services (QoS) features. In this paper, we explore the latest developments in related research fields. We summarize the 3GPP network slicing evolution, the Radio Access Network, and Core Network architectures.We describe background concepts correlated with inter-slice and intra-slice, as well as their management and
orchestration architectures. We extend our discussion to the taxonomy of NGWN resource allocation via a deep comparison of the optimization algorithms. Finally, we enrich our study
by including open issues and some recommendations for the future.