ontinued to be the core focus of the research and development in 5G. However, it should not be forgotten that the proper design of network architecture and functionality along with ease of programmability/configurability have been equally important to 5G to ultimately achieve the goal of an integrated communication plat- form serving multiple vertical markets and diverse consumer applications. Network function virtualization (NFV) has been an underlying method to enable network operators to create network slices per end-user application or service requirements with guaranteed perfor- mance and quality corresponding to service level agreements. Both cloud and edge comput- ing components will be needed in these network slices to address varying performance and latency requirements. Each network slice will rely on enhanced LTE and/or NR access tech- nologies to provide reliable wireless link between the user terminals and the network. The comprehensive research and studies conducted on 5G in the past few years and the ongoing standards development efforts are revealing a number of key technologies that have helped achieve the ambitious system and service requirements as follows (see Fig. 2): New spectrum: Use of large blocks of spectrum in higher frequency bands and hetero- geneous carrier aggregation (particularly above 6 GHz and up to 100 GHz) in addition to unlicensed spectrum have made wider system bandwidths (up to 3.2 GHz) feasible, leading to higher peak data rates and network capacity. New waveforms and multiple access schemes: OFDM-based LTE air-interface may not be suitable for some use cases, and therefore a number of new waveform candidates and multiple access schemes have been studied. However, the complexity and practical limitations of some of those new candidates have convinced the 3GPP community to adopt OFDM with adaptive numerology which would allow configurable frame struc- tures and radio resource allocations depending on use case, available spectrum, and bandwidth without affecting backward com