Network

The International Telecommunications Union (ITU) is currently working on a 4G cellular standard, to be released in a couple years. The technology would enable IP-based voice, data, and streaming multimedia at higher speeds. ITU-R (Radiocommunication Sector) is expected to require the technology, which it calls ITU-Advanced, to support data rates of at least 100 Mb/s, and use OFDMA, a multiuser version of OFDM. All 4G technologies will be IP-based and packet switched; whereas current 3G families — including WCDMA, HSDPA, CDMA2000, and EVDO — were built by optimising voice communications.

There are currently three candidates to be considered as 4G standards. They are the LTE (long-term evolution), UMB (ultramobile broadband), and WiMAX II (IEEE 802.16.m). Other candidates could also be submitted until 2009. Then the ITU-R will start working on detailed specifications.

LTE was developed by 3GPP (the GSM group, mainly Ericsson), while UMB was proposed by 3GPP (the CDMA 2000 group, mainly Qualcomm), and WiMAX II by WiMAX Forum (mainly Intel). The table above compares some aspects of the candidates. All transmissions use OFDMA, except uplink part of the LTE, which uses single-carrier FDMA to improve power efficiency. UMB promises to reach data rate up to 288 Mb/s (with 20 MHz band), while the LTE noted 250 Mb/s. WiMAX II promises to break 1 Gb/s barrier in stationary mode.

Industry observers speculate that ultimately, 4G could end up as a combination of different approaches. Worse :), different carriers could simply deploy the technology of their choice, regardless of standardisation. And, still, 4G adoption may not occur until the standards process plays out and vendors have begun recovering their investments in 3G and 3.5G technology.