5G Heterogeneous network is characterized with small cells in close proximity with one another which in most cases are active even at low traffic load periods. Such scenarios lead to unnecessary large energy consumption and co-frequency interference. This large energy consumption and interference in 5G heterogeneous networks have been an issue widely discussed in several technical literature. Different and attractive techniques on energy management have been investigated and proposed. All these have been in seeking ways of minimizing or reducing energy consumption in mobile networks. In this study the on/off and sleep-mode schemes as energy management techniques have been reviewed with the major aim of identifying weak areas of both techniques and suggesting ways which will be useful for further research works in the future. In doing so recent literature on the subject matter were consulted. The on/off and sleep-mode schemes involve switching processes which result to loss of data and information during change of state. Quality of service issues arising from incomplete or proper switching process and unnecessary delay perceived by the users were observed as major concern for both schemes. For further work, amongst other suggestions, it is suggested that the time needed between system switching command and switching operations be considered as an important factor in eliminating switching problems which will positively affect the overall quality of service.