It was previously shown that the number of array elements must exceed the number of sources for subspace-based steering vector estimation.This is clearly not practical for a wireless system since the number of mobile users is very large.To overcome the restriction

a blind adaptive technique based on subspace method to estimate steering vector of an antenna array is proposed.By summing the received signals of each element

the superposition of the signature waveforms of expected source is obtained.This superposition is also expressed by a group of bases of the signal subspace by subspace method.Since the superposition involves the steering vectors

the expected steering vector can be estimated without requiring the number of antenna elements being greater than that of data sources.Simulations demonstrate the effectiveness of the proposed algorithm.