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Dynamic Reuse Partitioning Within Cells Based on
Local Channel and Arrival Rate Fluctuations.
Mathias Johansson,
Dirac Research AB
IEEE Transactions on Vehicular Technology,
Vol. 57, no. 2, March 2008., pp. 1155-1165.
© IEEE
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Outline:
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Consider two base stations of a cellular wireless system
that are opposite to each other in a traditional
hexagonal cell pattern with 60 degree sectors.
If both
base stations use the same transmission bandwidth,
there will be a considerable interference for users
near the cell borders, whereas users close to either
of the base stations will experience little, if any,
interference from the other base station.
At some point, the interference levels become too
high for the border users, and it would be better
to set aside a certain part of the bandwidth for transmitting
to these users using only one base station
(or both, employing macrodiversity).
That way, total system throughput would increase.
The main problem that we will treat here lies in
identifying the right amount of bandwidth to use
for each transmission mode and dynamically adapting
this amount according to the actual demand for
capacity and supply thereof
(which indirectly measures the interference levels)
in different areas of the sector.
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Abstract:
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It is possible to improve the spectral efficiency of cellular
systems by dynamically repartitioning the available
band-width between different interfering and
noninterfering subareas within and among sectors.
Here, we investigate the problem of maximizing the
expected system throughput in a two-sector area by
dynamic bandwidth partitioning between two
transmission modes:
- using bandwidth in the low-interference
area near either of the base stations and
- using bandwidth for macrodiversity or
single-base station transmission to avoid interference.
Mode 2 is typically useful for giving users near the
cell border higher bit rates.
The suggested solution
adapts the bandwidth partitioning to reflect local
transmission capacities and bandwidth demands.
Thus, it automatically decides on whether both
trans-mission modes should be used and how much
bandwidth should be used in each mode.
The solution requires only limited knowledge of
the future arrival rates and channel qualities and
uses probability theory to find a robust bandwidth
partitioning.
Finally, we discuss access control
and when to switch a user between the transmission
modes to achieve high spectral efficiency and some
minimum average quality of service.
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Related publications:
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PhD Thesis
by Mathias Johansson
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IEEE Trans. IT paper
on resource allocation under uncertainty using
the maximum entropy principle.
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Source:
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Pdf (249K)
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