m Matlab simulation of wireless image transmission based on QPSK modulation and demodulation, including modules such as spread spectrum despread equalization

i love c programming 2022-11-24 21:59:48 阅读数:108

matlabsimulationwirelessimagetransmission

Table of Contents

1. Algorithm description

2. Preview of simulation effect

3. MATLAB partial code preview

4.Complete MATLAB program


1. Algorithm description

In the field of wireless communication, software radio is known as another revolution after the transition from analog communication to digital communication, and it has a wide range of applications in both military and civilian applications.It is a new wireless communication technology based on a general-purpose programmable hardware platform, and realizes as many communication functions as possible with software, so that the improvement and upgrade of the system are very convenient, and it is easy to achieve compatibility between different communication systems.Modulation and demodulation are the basic components of the baseband processing of the entire digital communication system, and basically construct the overall performance framework of the digital communication system.Among them, QPSK modulation and demodulation is a modulation and demodulation method with better performance, easy to realize and widely used in practice.

Quadrature Phase Shift Keying (QPSK) is a digital modulation method.It is divided into absolute phase shift and relative phase shift.Because there is a phase ambiguity problem in the absolute phase shifting method, the relative phase shifting method DQPSK is mainly used in practice.It has been widely used in wireless communication and has become a very important mode of modulation and demodulation in modern communication.

Quadrature Phase Shift Keying (QPSK) is a digital modulation method.It is divided into absolute phase shift and relative phase shift.Because there is a phase ambiguity problem in the absolute phase shifting method, the relative phase shifting method DQPSK is mainly used in practice.QPSK is a quaternary phase modulation, which has good anti-noise characteristics and frequency band utilization, and is widely used in communication services such as satellite links and digital trunking.This topic establishes the following image transmission process by using QPSK:


Using QPSK modulation, while ensuring the efficiency of signal transmission and bit error performance.

General QPSK implementation, also indicates higher order PSK implementation.In the constellation diagram the sine and cosine waves are used to transmit the written notation in terms of:

This creates four phases π/4, 3π/4, 5π/4 and 7π/4 needed.

This results with the unit basis function in a two-dimensional signal space being used as the in-phase component of the signal and the second basis function of the quadrature component of the signal.

The spread spectrum communication is characterized by the fact that the bandwidth used to transmit information is much larger than the bandwidth of the information itself.In this information transmission method, the transmitter uses spread spectrum coding (usually a pseudo-random code) to perform spread spectrum modulation.At the receiving end, the same code is used for related synchronous reception, despreading and recovery of transmitted information data.

2. Simulation effect preview

The matlab2022a simulation results are as follows:

3. MATLAB partial code preview

% generate spread spectrum gold code% The user generates a gold coded = phase_shift+1;shift = [d,d+1,d+2];[MSeq1] = fMSeqGen([1 0 0 1 0 1]);[MSeq2] = fMSeqGen([1 0 1 1 1 1]);% Generate a GOLD sequence from two M sequencesGoldSeq1 = fGoldSeq(MSeq1,MSeq2,shift(1));GoldSeq1(find(GoldSeq1==0)) = -1;GoldSeq2 = fGoldSeq(MSeq1,MSeq2,shift(2));GoldSeq2(find(GoldSeq2==0)) = -1;GoldSeq3 = fGoldSeq(MSeq1,MSeq2,shift(3));GoldSeq3(find(GoldSeq3==0)) = -1;Goldseqs = [GoldSeq1 GoldSeq2 GoldSeq3];Gold_Num = length(GoldSeq1);J = [zeros(1,(2*Gold_Num-1)) 0;eye(2*Gold_Num-1) zeros((2*Gold_Num-1),1)];%Modulation initial parametersphi = phi_mod;% Define the signal-to-noise ratioSNR = 10;%Define the channel information of the three users, modify the channel parameters, and complete the function realization of task1,2,3%arrayArray_Position = [-4 0 0;-3 0 0;1 0 0;3 0 0;4 0 0];% channel estimateRec = func_Rec_get(Xmatrix,GoldSeq1);[DOAest,Delayest] = fChannelEstimation(Rec,GoldSeq1,Array_Position,3)R = func_Reciver(Rec,DOAest,Delayest,Beta_1,Array_Position,GoldSeq1,3);DeQPSK = fDSQPSKDemodulator(R,GoldSeq1,phi);% restore textKey = DeQPSK(1:end-2);C1 = reshape(Key,8,60);for i = 1:60WordAsic(i) = C1(1,i)*2^0 + C1(2,i)*2^1 + C1(3,i)*2^2 + C1(4,i)*2^3 +...C1(5,i)*2^4 + C1(6,i)*2^5 + C1(7,i)*2^6 + C1(8,i)*2^7;KK{i} = char(WordAsic(i));end01_063_m

4. Complete MATLAB program

Matlab source code description_I love C programming blog-CSDN blog

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