  Block sparsity is an important parameter in many algorithms to successfully
recover block sparse signals under the framework of compressive sensing.
However, it is often unknown and needs to be estimated. Recently there emerges
a few research work about how to estimate block sparsity of real-valued
signals, while there is, to the best of our knowledge, no investigation that
has been conducted for complex-valued signals. In this paper, we propose a new
method to estimate the block sparsity of complex-valued signal. Its statistical
properties are obtained and verified by simulations. In addition, we
demonstrate the importance of accurately estimating the block sparsity in
signal recovery through a sensitivity analysis.
