NTT DoCoMo announced today that this month it began testing an experimental Super 3G system for mobile communications. DoCoMo hopes to achieve a downlink transmission rate of 300Mbps over cellular links using multiple antennas.

According to Wikipedia, the Long Term Evolution project is not a standard, but it will result in the new evolved release 8 of the UMTS standard, used by many 3G carriers (such as AT&T). “Super 3G” is an interim step before true “4G”, which is expected to arrive in about 5 years. “4G” is expected to provide 100Mbps/mobile and 1 Gbps (fixed) using OFDM.

NTT’s Super 3G flavor of LTE features a different approach than 3G’s, High-Speed Downlink Packet Access (HSDPA), with up to 14.4 Mbit/s down, and High-Speed Uplink Packet Access (HSUPA), with faster up-link speeds up to 5.76 Mbit/s. Both have evolved from 3G’s W-CDMA technology.

DoCoMo uses MIMO and OFDM modulation to increase speeds. They will begin with an indoor experiment using one transmitting and one receiving antenna, then expand the experiment to examine downlink transmission by employing up to four Multiple-Input Multiple-Output (MIMO) antennas for both the base station (transmission side) and mobile station (receiving side).

The goal is to achieve a downlink transmission speed of 300Mbps. The “handover function” — switching of the connection between two base stations will also be tested.

DoCoMo apparently believes Super 3G will allow the company to make LTE (long-term evolution) the transition technology to 4G. Super 3G can use the same radio spectrum band as current 3G services but it is fundamentally different technology.

3G Today and the CDMA Development Group promote CDMA evolution (i.e. EVDO rather than HSDPA). While CdmaOne (IS-95) and CDMA2000 utilize 2 x 1.25 MHz radio channels, future Qualcomm-backed CDMA evolution includes 1xEV-DO Rev. B and Ultra Mobile Broadband (UMB), which will enable operators to aggregate up to 15, 1.25 MHz channels in 20 MHz of spectrum.

GSM coalitions like 3GPP and 3G Americas have their own spin on 4G evolution (pdf). They plan to move from HSDPA to LTE (in 2-3 years), then on to “4G” (in 5 years).

DoCoMo hopes to complete the development of Super 3G technology — their spin on LTE — by 2009. They would like to sell Super 3G equipment and leverage that towards LTE.

MIMO is the basis for Mobile WiMAX, LTE and UMB. LTE uses OFDM in the downlink with variable channel widths and up to 2048 subcarriers (similar to Mobile WiMAX). For the Uplink, a new radio transmission scheme, called SC-FDMA, is designed to keep the peak to average power ratio as low as possible.

But Mobile WiMAX is already a standard and may have 8 million subscribers by 2010. Senza-Fili Consulting projects 54 million WiMAX subscribers by 2012, with growth driven by emerging markets. By 2012, 61% of WiMAX subscribers will use the technology for mobile access. A third of them will also use WiMAX as a fixed-access technology.

The IEEE 802.16e standard body is now developing a faster standard called 802.16m. It will deliver up to 100Mbps (mobile) and 1 Gbps (fixed). Upwardly mobile. The IEEE 802.16 submitted the OFDMA air interface, called IP-OFDM, for inclusion as the sixth IMT-2000 terrestrial radio interface as an ITU standard.

WiMAX Forum says a mid-sized city with a population of 1.75 million covering 1,500 km2 area (pdf) could start with low complexity base stations this year, then switch to more advanced base station antenna systems (with beamforming) in later years to match customer growth.

Mobile WiMAX proponents say it’s faster, cheaper and upwardly mobile. Right now.

What if they’re right?

Related DailyWireless articles include, Ericsson Pulls Plug on WiMAX, WiMAX 802.16m: 1Gbps, Mobile WiMAX - The Next Iridium?, Carriers Test “Real” 4G, Will Consumers Prefer WiMAX?, and Civil War in 4G.

Posted by Sam Churchill on Friday, July 13th, 2007 at 1:15 pm.