In theory, the third-generation (3G) broadband, packet-based transmission of text, digitized voice, video, and multimedia can offer a consistent set of services to mobile computer and phone users at data rates up to 2 Mbps (megabits per second), no matter where they are located in the world. However, in the real situations, the data rates may be lower than the theoretical standards.

Therefore, the basic requirement to 3G by ITU is that it must provide both voice communication and multi-media data services in an indoor, outdoor low-speed and high-speed moving environment at a data rate of 2Mbps, 384Kbps, and 144Kbps, respectively, with high service quality, high frequency efficiency and low cost. The detailed requirements include:

• Usability on all popular modes (cellular telephone, e-mail, paging, fax, video 　　conference, and Web browsing)
  
• High speed data transmission (upwards of 2 Mbps)
  
• Routing flexibility (repeater, satellite, LAN)
  
• Operation at approximately 2 GHz transmit and receive frequencies
  
• Roaming capability worldwide