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5 6 9 , 6 5 9
another knowledge site

LTE (So we choose ...) - 7

So we choose ... [Under LTE]
» E-UTRA, general description - 36.201, Rel 8 «

Before we start start studying HSPA, HSPA+, and LTE radio access, let us note down the choices made by 3GPP.

For LTE

We already noted in last article that for LTE, OFDM was chosen for downlink and DFTS-OFDM (SC-FDMA) was chosen for uplink. Both FDD and TDD configurations are supported. Bandwidth support for LTE ranges from 1 MHz to 20 MHz (which is 4 times of 3G BW of 5 MHz). Individual sub-carrier bandwidth is 15 kHz (12 sub-carriers) or 7.5 kHz (24 sub-carriers).

Following radio access techniques are used in LTE: channel quality based adaptation, Fast HARQ with soft combining, MIMO. Rel 5 3G feature HSDPA use (flexible) shared channel transmission to yield higher data rates under WCDMA limitations. Similar technique is used in LTE too.

For 3G+

Rel 5 introduced HSDPA and Rel 6 introduced HSUPA, collectively called HSPA. HSPA use (flexible) shared channel transmission, channel quality based adaptation, Fast HARQ with soft combining. Rel 7 introduced MIMO to further improve overall capacity.

In following articles, we will cover these in more details in following order:

3G+
- HSDPA
- HSUPA
- HSPA+ (MIMO)

LTE
- OFDM
- DFTS-OFDM (SC-FDMA)

References: 3G Evolution: HSPA and LTE by Dahlman, Parkvall, Sköld, and Beming, LTE - From Theory to Practice, Edited by Sesia, Toufik, and Baker, and Release 5, 6, 7 and 8 documents at 3gpp.

Copyright © Samir Amberkar 2010-11§

Diversity - 3 « LTE Index » 3G till Rel 6 - HSDPA