</title> </titles> <publication_date> <month>05</month> <year>2007</year> </publication_date> <pages> <first_page>1089</first_page> <last_page>1089</last_page> </pages> <publisher_item> <item_number item_number_type='arNumber'>4200931</item_number> </publisher_item> <doi_data> <doi>10.1109/TCOMM.2007.896145</doi> <resource>http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?a