Since the modulated symbols are visualized to be in frequency domain, it is converted to time-domain using IDFT. OFDM signal is a composite signal that contains information from subchannels. % ref -ideal constellation points that could be used by IQ detector % d - data symbols to be modulated drawn from the set % M - modulation order, For BPSK M=2, QPSK M=4, 256-QAM M=256 etc., Modulation_mapper.m: Implementing the modulation mapper for MPSK and MQAM function =modulation_mapper(MOD_TYPE,M,d)
#OFDM MATLAB OPTISYSTEM FULL#
Please refer the book Wireless communication systems using Matlab – for full Matlab code It is built over the mpsk_modulator.m and mqam_modulator.m functions given in sections 5.3.2 and 5.3.3 of chapter 5 (Refer the book Wireless communication systems using Matlab). The function supports MPSK modulation for and MQAM modulation that has square constellation. The following generic function implements the modulation mapper (constellation mapping) shown in the Figure 1. The components of the orthogonal subchannels in the frequency domain are converted to time domain using IDFT operation.įigure 1: Discrete-time simulation model for OFDM transmission and reception At this juncture, the modulated symbols on the parallel streams can be visualized as coming from different orthogonal subchannels in the frequency domain. Since this is a baseband discrete-time model, where the signals are represented at symbol sampling instants, the information symbol on each parallel stream is assumed to be modulating a single orthogonal carrier. The data symbol in each subchannel is modulated using the chosen modulation technique such as MPSK or MQAM. For convenience, the information stream is already represented as a symbol from the set. The transmission begins by converting the source information stream into parallel subchannels. The size of inverse discrete Fourier transform (IDFT) and discrete Fourier transform (DFT) need to be set accordingly. The number of subchannels is typically set to powers of 2, such as. The basic parameter to describe an OFDM system is to specify the number of subchannels ( ) required to send the data. The schematic diagram of a simplified cyclic-prefixed OFDM (CP-OFDM) data transmission system is shown in Figure 1. Wireless Communication Systems in Matlab (second edition), ISBN: 979-8648350779 available in ebook (PDF) format and Paperback (hardcopy) format.ĭiscrete-time implementation of baseband CP-OFDM.Simulate M-QPSK / M-QAM based cyclic prefixed OFDM over AWGN channel. Goal: Simulate discrete-time cyclic-prefixed OFDM communication system.