CH7.zip_codes mimo_mimo_mohinder jankiraman_space_space time

This demo is to acquaint the reader with the rudiments of coded OFDM (COFDM). The schematic as shown here is the one that is used as the basis for the PHY layer of IEEE 802.11a. as discussed in Chapter 8. Simulink lends itself to "real time" visualization of an OFDM system. A more elaborate simulink model is given in Chapter 8 for an IEEE 802.11a system. Type "simulink" at the MATLAB command line. This will open up the Simulink Library Browser. Using the File/Open command, open the COFDM model. Then use the Simulink/Start command to run the model. The user is encouraged to examine the channel parameters by double clicking the "Multipath Rayleigh Fading" block. This will open up the channel parameters. Note that the delay and the gain parameters are two element arrays, i.e.they define two paths in the channel.This signifies a narrow band channel(usually a two path array).The receiver spectrum will rise and fall together. In fact if we make the delay and the gain parameters into a single element array, i.e. just a single number signifying only one path,viz. the direct path (zero values for both delay and gain),the narrowband behavior becomes even more evident. Now increase these to a higher number of elements(paths) to simulate a wideband channel.The spectrum at the receiver will not rise and fall together. This simulates a wideband channel behavior. This model has been tested on MATLAB version 6.0 and above with SIMULINK with Communication and DSP blockset options.