Chapter 3Digital Wireless Communications
The next three chapters describe the principles of radio transmission and reception in LTE. Here, we begin by reviewing the radio transmission techniques that LTE has inherited from 2G and 3G communication systems. The chapter covers the principles of modulation and demodulation, describes how these principles are applied to a mobile cellular network and shows how the received signal can be degraded by noise, fading and inter-symbol interference. It then discusses the techniques that are used to minimize the number of errors in the received signal, notably forward error correction, re-transmissions and hybrid automatic repeat request. For some detailed accounts of the material covered in this chapter, see for example References [1–6].
These three chapters contain more mathematics than the others in this book, but it has been kept reasonably lightweight to ensure that the material is accessible to those without a mathematical background. Some of the more detailed aspects have been ring-fenced into individual sections, which readers can skip without detracting from their overall appreciation of the subject.
3.1 Radio Transmission and Reception
3.1.1 Carrier Signal
A key part of any radio communication system is the creation and transmission of a radio wave, also known as a carrier signal. Mathematically, we can express the carrier signal as follows:
Here, a is the amplitude of the radio wave, f is its frequency and φ is its initial ...
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