發送短信

數:

提供者:

CAPTCHA:

   _____    ______               ___     _    _   
  / ___//  /_   _//   ____      / _ \\  | \  / || 
  \___ \\   -| ||-   |    \\   / //\ \\ |  \/  || 
  /    //   _| ||_   | [] ||  |  ___  ||| .  . || 
 /____//   /_____//  |  __//  |_||  |_|||_|\/|_|| 
`-----`    `-----`   |_|`-`   `-`   `-` `-`  `-`  
                     `-`

Please enter what you see:

發送短信 : Where am I? Characterizing and improving the localization performance of off-the-shelf mobile devices through cooperation