Page 31 - EURECOM - RA2011GB

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it. “But this can only work if the network is not
overloaded and if bandwidth is sufficient”, under-
lines Professor Gesbert.
And enhancing performance!
EURECOM’s second approach is the complete
opposite of the first one: that is to use interference
rather than avoid it. This solution is unique and in
total contrastwithwhat isdone today. “Theunderly-
ing idea is to combine the antennas of various cells
by leveraging our knowledge in multi-cell systems
(MIMO)”, explains David Gesbert. But rather than
improve the signal quality by adding emitting and
receivingantennas, theARTIST4Gsolutionconsists
of optimizing the operation of existing antennas in
neighboring cells.
There isactuallynoantennabeingadded,whichis
the reasonwhy the technique has beennamed “vir-
tual MIMO”. With this technique, a mobile located
close toacellwill not be subject to interference from
the neighboring cell but will rather benefit from the
second antenna to manage part of the signal and
improve the quality of the cellular communication.
EURECOM researchers needed to optimize the
P. de Kerret, D. Gesbert
The Multiplexing Gain of the Network
MIMO Channel With Distributed CSI
Submitted to the IEEE Transactions on
Information, Theory, Aug. 2011.
R. Zakhour, D. Gesbert
Optimized data sharing in multicell
MIMO with finite backhaul capacity
in IEEE Transactions on Signal Processing,
Dec. 2011.
D. Gesbert, M. Kountouris
Rate Scaling Laws in Multicell
Networks under Distributed Power
Control and User Scheduling
in IEEE Trans. On Information Theory, Jan. 2011.
H. J. Bang, D. Gesbert, P. Orten
On the rate gap between multi and
single cell processing under
opportunistic scheduling
in IEEE Trans. on Signal Processing, Jan. 2012.
Maps showing the quality of service and the improvement due to technical ARTIST4G
existingalgorithms but theyalsohad to solve a criti-
cal issue: find themoment at which amobile signal
must be transmitted over both antennas to avoid
jeopardizingthequalityof theservice forotherusers.
To do this, the main cell had to be able to share the
information from the mobile signal with the neigh-
boring station. The difficultywas todevelopdistrib-
uted transmission methods in order to reduce the
quantity of information to be transmitted.
Akey part of these concepts and those developed
by the project partnerswas testedat the endof 2011.
Theconclusionsof theArtist4Gproject areexpected
in2012. Theyshouldundoubtedlyhavegreat impact
on the 4G standards.
Head of Mobile
Communications Dept.
MOBILE communications
Cell edge users obtain
only fraction of
average throughput
Conventional LTE system
System with ARTIST4G
techniques (e.g. interference
System with ARTIST4G techniques
(e.g. advanced relaying)
Cell edge users
experience strongly
Base station
14.2 Mbps
1,8 Mbps
Better user experience
Better user experience
Better user experience
Relay mode locations
2011annual report