Fig. 2 shows the symbol-error-rate (SER) performances of all
the schemes. It is observed that S1 is better than S2 and S3 is
better than S4 at all rates. Thus if we select the VNs from GR
rather than selecting randomly, the performance is improved
for both the optimized recoverable patterns in Table II and the
optimum distributions in [3] and [4]. It is also observed that