389 research outputs found
Improving Macrocell - Small Cell Coexistence through Adaptive Interference Draining
The deployment of underlay small base stations (SBSs) is expected to
significantly boost the spectrum efficiency and the coverage of next-generation
cellular networks. However, the coexistence of SBSs underlaid to an existing
macro-cellular network faces important challenges, notably in terms of spectrum
sharing and interference management. In this paper, we propose a novel
game-theoretic model that enables the SBSs to optimize their transmission rates
by making decisions on the resource occupation jointly in the frequency and
spatial domains. This procedure, known as interference draining, is performed
among cooperative SBSs and allows to drastically reduce the interference
experienced by both macro- and small cell users. At the macrocell side, we
consider a modified water-filling policy for the power allocation that allows
each macrocell user (MUE) to focus the transmissions on the degrees of freedom
over which the MUE experiences the best channel and interference conditions.
This approach not only represents an effective way to decrease the received
interference at the MUEs but also grants the SBSs tier additional transmission
opportunities and allows for a more agile interference management. Simulation
results show that the proposed approach yields significant gains at both
macrocell and small cell tiers, in terms of average achievable rate per user,
reaching up to 37%, relative to the non-cooperative case, for a network with
150 MUEs and 200 SBSs
Spectrum Sharing Opportunities of Full-Duplex Systems using Improper Gaussian Signaling
Sharing the licensed spectrum of full-duplex (FD) primary users (PU) brings
strict limitations on the underlay cognitive radio operation. Particularly, the
self interference may overwhelm the PU receiver and limit the opportunity of
secondary users (SU) to access the spectrum. Improper Gaussian signaling (IGS)
has demonstrated its superiority in improving the performance of interference
channel systems. Throughout this paper, we assume a FD PU pair that uses proper
Gaussian signaling (PGS), and a half-duplex SU pair that uses IGS. The
objective is to maximize the SU instantaneous achievable rate while meeting the
PU quality-of-service. To this end, we propose a simplified algorithm that
optimizes the SU signal parameters, i.e, the transmit power and the circularity
coefficient, which is a measure of the degree of impropriety of the SU signal,
to achieve the design objective. Numerical results show the merits of adopting
IGS compared with PGS for the SU especially with the existence of week PU
direct channels and/or strong SU interference channels
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