Before revision:  Moreover, we find that the bounded delay region of Geometric Retransmission is the same as its stable throughput region; but that of Exponential Backoff is only a sub-set of its stable throughput region due to the capture effect, which causes large variances of the service time of input packets  .
After revision:  Moreover, we find that the bounded delay region of exponential backoff is only a sub-set of its stable throughput region due to the capture effect, which causes large variances of the service time of input packets .