NTT Super 3G

NTT “Super 3G”

Posted by samc on July 13th, 2007

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.

Comparison of 3G and ‘Super 3G’ SOURCE: Unstrung

	3G W-CDMA	3.5G HSPA (HSDPA/HSUPA)	3.9G ‘Super 3G’
Spectrum	3G spectrum*	3G spectrum*	3G spectrum*
Spectrum bandwidth	5MHz	5MHz	1.4, 3, 5, 10, 15, 20MHz
Radio access scheme	DS-CDMA	DS-CDMA	OFDMA (downlink), SC-FDMA (uplink)
Peak data rate (uplink)	384 Kbit/s	5.7 Mbit/s	80 Mbit/s
Peak data rate (downlink)	384 Kbit/s	14 Mbit/s	300 Mbit/s
Source: NTT DoCoMo * 2GHz band and additional spectrum for 3G DS-CDMA = Direct Sequence Code Division Multiple Access OFDMA = Orthogonal Frequency Division Multiple Access SC-FDMA = Single Carrier Frequency Division Multiple Access

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.

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.

DoCoMo seeks to develop Super 3G equipment and expects to complete development of Super 3G technology by 2009.

They’ll have competition from Mobile WiMAX, of course. The IEEE 802.16e standard is moving up to 1 Gbps using an evolution of the standard called 802.16m. 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.