Waveforms in 3G - Part II — Lesson 3

This lesson discusses the air interface properties in 3G and how they lay the foundation for multi-carrier systems essential for understanding 4G and 5G waveforms. The lesson also explains the transmitter structure, modulation part, channel, and receiver part. It delves into the concept of spread spectrum communication, direct sequence spread spectrum, and the design of codes. The lesson further explores the QPSK modulation, receiver structure, and the rake receiver architecture. It also discusses the method for allowing variable spreading factor and the concept of overloading. The lesson concludes with the introduction of fast power control and the outer loop slow control in the third generation system.

Video Highlights

00:18 - Introduction
03:28 - Pulse amplitude modulation and the class of non-Linear WCDMA and concept of variable spreading factor
04:17 - Explanation of how the original codes can be split to generate different code sets
16:33 - Concept of soft handover and the introduction of HARQ mechanism in 3G
24:29 - Fast transmit power control and the concept of outer loops slow TPC based modulation

Key Takeaways

- Spread spectrum communication and direct sequence spread spectrum are key concepts in understanding the waveform structure.
- The design of codes plays a crucial role in the modulation process.
- The QPSK modulation and receiver structure are integral parts of the air interface.
- The rake receiver architecture is used to capture multi-path signals.
- The method for allowing variable spreading factor provides flexibility in allowing different data rates.
- The Hybrid Automatic Repeat Request (HARQ) mechanism and fast power control are important mechanisms introduced in the third generation system.