ons while offering end users continuous, untethered, always-on access to the Internet and next-generation data services. IS-95 HDR is categorized as a 3G technology. cdmaOne offers numerous benefits to cellular operators and their subscribers, including capacity increases of 8 to 10 times that of an AMPS analog system and 4 to 5 times that of a GSM system; improved call quality, with better and more con- sistent sound compared to AMPS systems; simplified system planning through the use of the same frequency in every sector of every cell; enhanced privacy; improved coverage characteristics, allowing for the possibility of fewer cell sites; increased talk time for portables; and bandwidth-on-demand. Chapter 14 Wireless WANs Personal Digital Cellular (PDC) is a 2G standard developed and used exclusively in Japan. It was originally defined in April 1991 by the standards body that is today known as the Association of Radio Industries and Businesses (ARIB). At its peak, PDC had more than 80 million subscribers, but with Japan's aggressive deployment of 3G mobile networks, as of December 2005, the number of PDC subscribers had dropped by nearly half, to 45.86 million. PDC is based on TDMA and FDD schemes. It is the most spectrally efficient of the TDMA technologies, with six half-rate (or three full-rate) channels possible in a 25KHz frequency space, compared to three channels in a 30KHz space in IS-136 and eight channels in a 200KHz space for GSM. PDC can operate in two modes: full rate and half rate. Half-rate channels have reduced speech quality and data trans- mission rates but allow more channels to occupy the same bandwidth. Two voice codecs are supported, including a low-bit-rate 9.6Kbps codec for full-rate voice and a 5.6Kbps codec for half-rate voice. PDC is implemented in two frequency bands: the 800MHz band (specifically, 810MHz to 888MHz downlink and 893MHz to 958MHz uplink) and the 1,500MHz band (at 1,477MHz to 1,501MHz downlink and 1,429MHz to 1,453MHz uplink). The 1,500MHz band allows for the use of much 