5G today: Modulation technique alternatives

Cellular wireless or mobile communications have seen four generations of technological developments. Today, technologists are proposing a Fifth Generation (5G) for around 2020. Most consider this time to be when the infrastructure will need to be renewed. Together with this observation, it is usually argued that, the new generation technology should possess a number of features. There is no consensus on what these new features should be. Some argue that we are facing a new generation of devices that will have continuous Internet connectivity, and consequently there will be more machine to-machine or machine-type communications. It is argued that machine-type communication will require very low latency. Others argue that the demand for services will increase by about three orders of magnitude and the new technology should be designed to support this tremendous increase, perhaps handling each order of magnitude by means of a different approach. In this paper, we discuss the modulation techniques proposed for 5G and their justification.