Unveiling 5G wireless networks: emerging research advances, prospects, and challenges [Guest Editorial]

To cope with the high traffic volume demands spurred by the proliferation and penetration of 4G services, significant improvements to wireless access techniques have been made. Notable examples are massive multiple-input multiple-output (MIMO), coordinated multipoint (CoMP) transmission and reception, and D2D (device-to-device) incorporated in 3G and 4G specifications. Furthermore, to boost network coverage and capacity, mobile operators have also been increasingly deploying heterogeneous networks (HetNets), consisting of micro-, pico-, and small/femtocells. However, despite these advances in core wireless technologies, Third Generation Partnership Project (3GPP) mobile networks are still challenged to handle the ever increasing mobile traffic, particularly due to the use of specific-purpose networking equipment that can neither dynamically scale with mobile traffic nor easily be upgraded with new functions.