【PDF下载】3GPP LTE 物理层标准的概念与技术的详细说明-2.pdfVIP

Chapter 2: Key Technologies of the LTE Physical Layer Objective Some of your questions that will be answered during this session… s ? What is OFDM and how does it differ from OFDMA? ? How does IFFT relate to OFDM? ? What is a cyclic prefix, why can it differ in duration and what is it used for? ? How MIMO is applied in order to multiply the throughput compared to systems with a single antenna? © INACON GmbH 1999 - 2009. All rights reserved. Reproduction and/or unauthorized use of this material is prohibited - 89 and will be prosecuted to the full extent of German and international laws. Version Number 2.030 2.1 Introduction OFDM Technology 2.1.1 Impact of Orthogonality in the Frequency Domain – 3 Steps The objectives of this section are to provide a 3D-view of sine waves and to pave the way to understand orthogonality. Image Description ? The image illustrates 3 different sine waves on 3 different frequencies. ? The image provides two different perspectives: in the upper left part (cylinder) the image presents the time domain while in the lower right part the frequency domain is highlighted. In the OFDM-terminology, the 3 different frequencies are usually called subcarriers or tones. Provided their carrier frequency is different not modulated carriers can always be perfectly separated. Room for your Notes • Abbreviations of this Section: OFDM Orthogonal Frequency Division Multiplexing © INACON GmbH 1999 - 2009. All rights reserved. Reproduction and/or unauthorized use of this material is prohibited - 91 and will be prosecuted to the full extent of German and int