16 and 64 QAM LabVIEW

Introduction In this lab, we aim at analyzing the BER for PSK in AWGN channel on LabVIEW. And achieve two kinds of basic QAM which are 16 QAM and 64 QAM. After that, we recorded the BER of each PSK with different SNR. By analysis data, we can find that when the SNR increased, the BER decreased. Then we use USRP to simulate these programs. Before we do this experiment, we need to know some theoretical knowledge. Like, the principle of 16 QAM and 64 QAM. So in this report, I’d like to make a brief introduction of them. Principle of QAM Quadrature Amplitude Modulation, QAM utilises both amplitude and phase components to provide a form of modulation that is able to provide high levels of spectrum usage efficiency. Figure 1 The concept of QAM It has been used for some analogue transmissions including AM stereo transmissions, but it is for data applications where it has come into its own. It is able to provide a highly effective form of modulation for data and as such it is used in everything from cellular phones to Wi-Fi and almost every other form of high speed data communications system. When QAM was used for digital transmission for radio communications applications is able to carry higher data rates than ordinary amplitude modulated schemes and phase modulated schemes. Basic signals exhibit only two positions which allow the transfer of either a 0 or 1. Using QAM there are many different points that can be used, each having defined values of phase and amplitude. This is known as a constellation diagram. The different positions are assigned different values, and in this way a single signal is able to transfer data at a much higher rate. Figure 2 Constellation diagram for a 16QAM signal showing the location of the different points As shown above, the constellation points are typically arranged in a square grid with equal horizontal and vertical spacing. Although data is binary the most common forms of QAM, although not all, are where constellation can form a square with the number of points equal to a power of 2 i.e. 4, 16, 64 . . .., i.e. 16QAM, 64QAM, etc. By using higher order modulation formats, i.e. more points on the constellation, i