Tuesday, 27 October 2015

LTE-Advanced introduction

1、LTE-Advanced (LTE-A) in 3GPP Release 10
 ITU has defined schedule for IMT-Advanced (IMT-A) with submission deadline October 2009
1st technical 3GPP workshop in April 2008
Until end of 2008 the clear focus was on LTE Release 8
The same multiple access to be used also in LTE-Advanced as in LTE
3GPP during 2009 to work with the LTE-Advanced study item, no specifications available until end of 2010 (technical report in 2009), specification to be frozen approximately 06/2011
 2、Requirements for LTE-Advanced
 The ITU-R has defined the requirements for a technology to quality as IMT-Advanced technology
Data rates required:
Local area data rate up to 1 Gbps and wide area 100 Mbps
For the capacity both 3GPP and ITU have defined requirements
3GPP has in some cases slightly different requirements that ITU-R
Analysis (in 3GPP study item) has shown that requirements can be met, but needs some technologies which at this time are more for meeting the requirements than market needs
􀂃 For example downlink 8 antenna transmission only included to fullfill ITU-R requirements
􀂃 Highest cases with capacity requirement up to 3 bits/Hz/cell
Also larger bandwidths and frequency band aggregation needed
 3、Bandwidth Extension
High peak data rate of 1 Gbps in downlink and 500 Mbps in uplink can be achieved with bandwidth extension from 20 MHz up to 100 MHz.
Backwards compatibility requirements with Release 8 LTE is achieved with carrier aggregation
We combine N Release 8 component carriers, together to form N x LTE bandwidth, for example 5 x 20 MHz = 100 MHz etc.
LTE terminals receive/transmit on one component carrier, whereas LTE Advanced terminals may receive/transmit on multiple component carriers simultaneously to reach the higher bandwidths.
4、Coordinated Multipoint Transmission (CoMP)
       Other-cell interference traditionally degrades the cellular system capacity. It is beneficial to isolate the cells by a wall.
The target in CoMP is to turn the other cell interference into useful signal. In that case, it is beneficial to “tear down the wall”.
But, practical challenges remain as many studies assume e.g. ideal signal estimation and/or ideal connection between sites (no delay, infinite bandwidth.
 5、Relays (RN=Relay Node)
 Main focus is on single-hop relays.
Main assumption self-backhauled base stations but alternatives are still being discussed.
Each relay looks like an independent cell, backhaul provided by an in-band connection to the serving base station.
6、LTE-Advanced Push Performance
 LTE-Advanced includes a toolbox of solutions improving radio performance
1。Multiple component carriers on the same or different spectrum
2。Including more transmit and receive antennas in downlink and in uplink,
() without increasing the number of antennas
3。Coordinated multipoint transmission
4。Optimized usage of local and wide area cells
    5。Decoding and encoding relay – similar to self backhauled base station

Budi Prasetyo

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