641 research outputs found
Downlink and Uplink Decoupling: a Disruptive Architectural Design for 5G Networks
Cell association in cellular networks has traditionally been based on the
downlink received signal power only, despite the fact that up and downlink
transmission powers and interference levels differed significantly. This
approach was adequate in homogeneous networks with macro base stations all
having similar transmission power levels. However, with the growth of
heterogeneous networks where there is a big disparity in the transmit power of
the different base station types, this approach is highly inefficient. In this
paper, we study the notion of Downlink and Uplink Decoupling (DUDe) where the
downlink cell association is based on the downlink received power while the
uplink is based on the pathloss. We present the motivation and assess the gains
of this 5G design approach with simulations that are based on Vodafone's LTE
field trial network in a dense urban area, employing a high resolution
ray-tracing pathloss prediction and realistic traffic maps based on live
network measurements.Comment: 6 pages, 7 figures, conference paper, submitted to IEEE GLOBECOM 201
A Data-Aided Channel Estimation Scheme for Decoupled Systems in Heterogeneous Networks
Uplink/downlink (UL/DL) decoupling promises more flexible cell association
and higher throughput in heterogeneous networks (HetNets), however, it hampers
the acquisition of DL channel state information (CSI) in time-division-duplex
(TDD) systems due to different base stations (BSs) connected in UL/DL. In this
paper, we propose a novel data-aided (DA) channel estimation scheme to address
this problem by utilizing decoded UL data to exploit CSI from received UL data
signal in decoupled HetNets where a massive multiple-input multiple-output BS
and dense small cell BSs are deployed. We analytically estimate BER performance
of UL decoded data, which are used to derive an approximated normalized mean
square error (NMSE) expression of the DA minimum mean square error (MMSE)
estimator. Compared with the conventional least square (LS) and MMSE, it is
shown that NMSE performances of all estimators are determined by their
signal-to-noise ratio (SNR)-like terms and there is an increment consisting of
UL data power, UL data length and BER values in the SNR-like term of DA method,
which suggests DA method outperforms the conventional ones in any scenarios.
Higher UL data power, longer UL data length and better BER performance lead to
more accurate estimated channels with DA method. Numerical results verify that
the analytical BER and NMSE results are close to the simulated ones and a
remarkable gain in both NMSE and DL rate can be achieved by DA method in
multiple scenarios with different modulations
Leveraging Decoupling in Enabling Energy Aware D2D Communications
Downlink/Uplink decoupling (DUDe) in LTE net-
works has caught the attention of researchers as it provides
better
uplink SINR and reduced power consumption per device due to
decoupled connection of a device with the Macro (in downlink
)
and a small cell (in uplink). These characteristics of DUDe c
an
be exploited to encourage more D2D communications in the
network. This paper first proposes a model to estimate decoup
ling
region within which a device is allowed to perform DUDe. Then
,
it formulates an equation to calculate the total power saved
by devices due to decoupling. Finally, the extra area due to
decoupling which can be used to enable D2D pairs is calculate
d.
Simulation results are shown based on different simulation
scenarios for different objectives for better understandi
ng the
idea proposed
Tractable Resource Management with Uplink Decoupled Millimeter-Wave Overlay in Ultra-Dense Cellular Networks
The forthcoming 5G cellular network is expected to overlay millimeter-wave
(mmW) transmissions with the incumbent micro-wave ({\mu}W) architecture. The
overall mm-{\mu}W resource management should therefore harmonize with each
other. This paper aims at maximizing the overall downlink (DL) rate with a
minimum uplink (UL) rate constraint, and concludes: mmW tends to focus more on
DL transmissions while {\mu}W has high priority for complementing UL, under
time-division duplex (TDD) mmW operations. Such UL dedication of {\mu}W results
from the limited use of mmW UL bandwidth due to excessive power consumption
and/or high peak-to-average power ratio (PAPR) at mobile users. To further
relieve this UL bottleneck, we propose mmW UL decoupling that allows each
legacy {\mu}W base station (BS) to receive mmW signals. Its impact on mm-{\mu}W
resource management is provided in a tractable way by virtue of a novel
closed-form mm-{\mu}W spectral efficiency (SE) derivation. In an ultra-dense
cellular network (UDN), our derivation verifies mmW (or {\mu}W) SE is a
logarithmic function of BS-to-user density ratio. This strikingly simple yet
practically valid analysis is enabled by exploiting stochastic geometry in
conjunction with real three dimensional (3D) building blockage statistics in
Seoul, Korea.Comment: to appear in IEEE Transactions on Wireless Communications (17 pages,
11 figures, 1 table
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