The fifth generation (5G) of cellular networks is expected to provide a wide variety of high rate multimedia services, with speeds of 300 Mbps and 60 Mbps in the downlink and uplink, respectively, at 95% of locations and times . The 5G communication platform is seen as a global unified standard with seamless connectivity across existing standards: high speed packet access, Long-Term Evolution-Advanced (LTE-A), and wireless fidelity (WiFi). Some of the emerging features and trends of 5G networks are:
- multi-tier dense heterogeneous networks [2, 3]
- device-to-device (D2D) and machine-to-machine (M2M) communications [3, 4]
- densification of the heterogeneous base stations (e.g., extensive use of relays and small cells) 
- cloud-based radio access network 
- integrated use of multiple radio access technologies 
- wireless network virtualization 
- massive and 3D MIMO [3, 7]
- millimeter waves 
- full duplex  communications.
Conventional 3G systems are single-tier and based on code division multiple access (CDMA) technology. In CDMA systems, all network nodes use the same frequency resource and are distinguished from each other by different pseudo-random spreading codes, which are not exactly orthogonal. Therefore, interference among the nodes is closely related to transmit power. Through efficient power control and spreading schemes ...