© 2020 IEEE.Heterogeneous Network (HetNet) is an architecture that contributes significantly to offering high performance and better throughput in future networks. However, ensuring a seamless connection during users' mobility is a key challenge in HetNet. Meanwhile, securing stable wireless access with good Quality of Service (QoS) for mobile users has become more challenging due to the rapid growth of mobile data traffic. Therefore, ensuring seamless communication requires efficient mobility management techniques to be used in HetNet, especially with the inclusion of 5G networks. To the best of our knowledge, conventional techniques have been used in the previous technologies may not be capable to meet the requirements of future HetNets. Thus, this paper provides a brief overview of mobility management concepts and techniques used in 5G HetNets. It also discusses various handover solutions in order to highlight them for more investigations need in the next mobile communication systems. Meanwhile, this paper presents parts of the key challenges related o mobility management issues in 5G HetNets which need to be addressed in future mobile networks.