Punctured Space-Time Convolutional Codes for Adaptive Modulation Schemes

Space-time trellis codes for an M-PSK modulation scheme are usually represented using a generator matrix whose elements are integers between 0 and M. Another way of representing them is to use a conventional binary convolutional code. Space-time convolutional codes can achieve an error performance very close to that of the best conventional mod-M space-time codes. The advantage of the binary representation is that it is more flexible and allows an easy implementation of space-time codes for different modulation schemes or numbers of transmit antennas. Only the rate of the convolutional code needs to be changed using the puncturing technique to accommodate these different schemes. New codes that can yield a spectral efficiency of 1, 2 and 3 bits/s/Hz by varying the rate and the modulation scheme will be presented in this paper. Simulations results show that their error performance is close to that of the best known space-time codes with the same spectral efficiency.