Wireless Communication - Eight: Quadrature Amplitude Modulation

This is the eighth in a series of computer science lessons about wireless communication and digital signal processing. In these lessons you’ll learn about the nature of electromagnetic radiation, digital modulation and multiplexing techniques, and how to get the best out of mobile communication systems such as LTE, 5G and WiFi. In this particular lesson, you’ll learn about one of the most versatile modulation techniques, namely Quadrature Amplitude Modulation, or QAM for short. QAM is used in most high speed data transfer applications including WiFi, mobile phones, cable TV and fibre optic networks. QAM can achieve some of the highest possible data rates by combining amplitude modulation with phase modulation. You will learn how a 16-QAM signal is generated and that it makes use of 16 unique wave forms of varying amplitude and phase in order to encode 4 bits per symbol. You will also learn about higher orders of QAM such as 256-QAM and 1024-QAM which is employed by the WiFi 6 standard. The limitations QAM in terms of bandwidth and power requirements are also mentioned, particularly when it comes to higher orders of QAM.
Chapters:
00:00 Introduction
00:20 Applications of QAM
01:00 16-QAM wave forms
01:22 16-QAM line coding
04:07 QAM constellation diagram
05:05 Limitations of QAM
05:27 Higher orders of QAM
06:40 Adaptive wireless communication systems

[@Waccoon]

First time I heard about 256QAM, I thought to myself, "There's no way that could possibly work except by magic."
It's been 30 years since I went to college to study computer science, and after all these years it still feels like magic.

[@ComputerScienceLessons]

I must agree, when you look at the complexities, the mind boggles. I can't help but admire the people who developed all this technology. :)KD

[@lukehjo]

Awesome explanation, keep it up.

[@ComputerScienceLessons]

Thank you :)KD