[1] Xian Univ Posts & Telecommun, Coll Commun & Informat Engn, Xian 710000, Peoples R China
[2] Nanjing Univ Aeronaut & Astronaut, Coll Elect & Informat Engn, Nanjing 210000, Peoples R China
[3] Nanjing Univ Aeronaut & Astronaut, Key Lab Dynam Cognit Systm Electromagnet Spectrum, Nanjing 210000, Peoples R China
[4] Utah State Univ, Dept Elect & Comp Engn, Logan, UT 84322 USA