398 research outputs found
Performance Limits of Compressive Sensing Channel Estimation in Dense Cloud RAN
Towards reducing the training signaling overhead in large scale and dense
cloud radio access networks (CRAN), various approaches have been proposed based
on the channel sparsification assumption, namely, only a small subset of the
deployed remote radio heads (RRHs) are of significance to any user in the
system. Motivated by the potential of compressive sensing (CS) techniques in
this setting, this paper provides a rigorous description of the performance
limits of many practical CS algorithms by considering the performance of the,
so called, oracle estimator, which knows a priori which RRHs are of
significance but not their corresponding channel values. By using tools from
stochastic geometry, a closed form analytical expression of the oracle
estimator performance is obtained, averaged over distribution of RRH positions
and channel statistics. Apart from a bound on practical CS algorithms, the
analysis provides important design insights, e.g., on how the training sequence
length affects performance, and identifies the operational conditions where the
channel sparsification assumption is valid. It is shown that the latter is true
only in operational conditions with sufficiently large path loss exponents.Comment: 6 pages, two-column format; ICC 201
Exploiting Frequency and Spatial Dimensions in Small Cell Wireless Networks
This paper examines the efficiency of spatial and frequency dimensions in
serving multiple users in the downlink of a small cell wireless network with
randomly deployed access points. For this purpose, the stochastic geometry
framework is incorporated, taking into account the user distribution within
each cell and the effect of sharing the available system resources to multiple
users. An analysis of performance in terms of signal-to-interference-ratio and
achieved user rate is provided that holds under the class of non-cooperative
multiple access schemes. In order to obtain concrete results, two simple
instances of multiple access schemes are considered. It is shown that
performance depends critically on both the availability of frequency and/or
spatial dimensions as well as the way they are employed. In particular,
increasing the number of available frequency dimensions alone is beneficial for
users experiencing large interference, whereas increasing spatial dimensions
without employing frequency dimensions degrades performance. However, best
performance is achieved when both dimensions are combined in serving the users.Comment: IEEE WCNC '1
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