  Parameter recovering of channel codes is important in applications such as
cognitive radio. The main task for that of a turbo code is to recover the
interleaver. The existing optimal algorithm recovers interleaver parameters
incrementally one by one. This algorithm continues till the end even if it has
failed in the halfway. And there would be lots of wasted computation, as well
as incorrectly recovered parameters that will badly deteriorate turbo decoding
performance. To address such drawbacks, this paper proposes an early stopping
method for the algorithm. Thresholds needed for the method are set through
theoretical analysis. Simulations show that the proposed method is able to stop
the algorithm in time after it has failed, while no significant degradation in
the correct recovering probability is observed.
