297,664 research outputs found
Interference Management in Heterogeneous Networks with Blind Transmitters
Future multi-tier communication networks will require enhanced network
capacity and reduced overhead. In the absence of Channel State Information
(CSI) at the transmitters, Blind Interference Alignment (BIA) and Topological
Interference Management (TIM) can achieve optimal Degrees of Freedom (DoF),
minimising network's overhead. In addition, Non-Orthogonal Multiple Access
(NOMA) can increase the sum rate of the network, compared to orthogonal radio
access techniques currently adopted by 4G networks. Our contribution is two
interference management schemes, BIA and a hybrid TIM-NOMA scheme, employed in
heterogeneous networks by applying user-pairing and Kronecker Product
representation. BIA manages inter- and intra-cell interference by antenna
selection and appropriate message scheduling. The hybrid scheme manages
intra-cell interference based on NOMA and inter-cell interference based on TIM.
We show that both schemes achieve at least double the rate of TDMA. The hybrid
scheme always outperforms TDMA and BIA in terms of Degrees of Freedom (DoF).
Comparing the two proposed schemes, BIA achieves more DoF than TDMA under
certain restrictions, and provides better Bit-Error-Rate (BER) and sum rate
performance to macrocell users, whereas the hybrid scheme improves the
performance of femtocell users.Comment: 30 pages, 18 figure
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
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