Visitors listen to the introduction of the mobile broadband technology of Huawei Technologies Co., Ltd. during the 4G Expo in Chicago, the United States, Oct. 19, 2010. The three-day expo kicked off here on Tuesday with the participation of some 150 top 4G companies from around the world. [Xinhua]

An exhibitor shows an electricity meter using 4G communication technology during the 4G Expo in Chicago, the United States, Oct. 19, 2010.  [Xinhua]