2,401 research outputs found
Spectrum Sharing in mmWave Cellular Networks via Cell Association, Coordination, and Beamforming
This paper investigates the extent to which spectrum sharing in mmWave
networks with multiple cellular operators is a viable alternative to
traditional dedicated spectrum allocation. Specifically, we develop a general
mathematical framework by which to characterize the performance gain that can
be obtained when spectrum sharing is used, as a function of the underlying
beamforming, operator coordination, bandwidth, and infrastructure sharing
scenarios. The framework is based on joint beamforming and cell association
optimization, with the objective of maximizing the long-term throughput of the
users. Our asymptotic and non-asymptotic performance analyses reveal five key
points: (1) spectrum sharing with light on-demand intra- and inter-operator
coordination is feasible, especially at higher mmWave frequencies (for example,
73 GHz), (2) directional communications at the user equipment substantially
alleviate the potential disadvantages of spectrum sharing (such as higher
multiuser interference), (3) large numbers of antenna elements can reduce the
need for coordination and simplify the implementation of spectrum sharing, (4)
while inter-operator coordination can be neglected in the large-antenna regime,
intra-operator coordination can still bring gains by balancing the network
load, and (5) critical control signals among base stations, operators, and user
equipment should be protected from the adverse effects of spectrum sharing, for
example by means of exclusive resource allocation. The results of this paper,
and their extensions obtained by relaxing some ideal assumptions, can provide
important insights for future standardization and spectrum policy.Comment: 15 pages. To appear in IEEE JSAC Special Issue on Spectrum Sharing
and Aggregation for Future Wireless Network
Resource Allocation for Outdoor-to-Indoor Multicarrier Transmission with Shared UE-side Distributed Antenna Systems
In this paper, we study the resource allocation algorithm design for downlink
multicarrier transmission with a shared user equipment (UE)-side distributed
antenna system (SUDAS) which utilizes both licensed and unlicensed frequency
bands for improving the system throughput. The joint UE selection and
transceiver processing matrix design is formulated as a non-convex optimization
problem for the maximization of the end-to-end system throughput (bits/s). In
order to obtain a tractable resource allocation algorithm, we first show that
the optimal transmitter precoding and receiver post-processing matrices jointly
diagonalize the end-to-end communication channel. Subsequently, the
optimization problem is converted to a scalar optimization problem for multiple
parallel channels, which is solved by using an asymptotically optimal iterative
algorithm. Simulation results illustrate that the proposed resource allocation
algorithm for the SUDAS achieves an excellent system performance and provides a
spatial multiplexing gain for single-antenna UEs.Comment: accepted for publication at the IEEE Vehicular Technology Conference
(VTC) Spring, Glasgow, Scotland, UK, May 201
Energy-Efficient Multi-View Video Transmission with View Synthesis-Enabled Multicast
Multi-view videos (MVVs) provide immersive viewing experience, at the cost of
heavy load to wireless networks. Except for further improving viewing
experience, view synthesis can create multicast opportunities for efficient
transmission of MVVs in multiuser wireless networks, which has not been
recognized in existing literature. In this paper, we would like to exploit view
synthesis-enabled multicast opportunities for energy-efficient MVV transmission
in a multiuser wireless network. Specifically, we first establish a
mathematical model to characterize the impact of view synthesis on multicast
opportunities and energy consumption. Then, we consider the optimization of
view selection, transmission time and power allocation to minimize the weighted
sum energy consumption for view transmission and synthesis, which is a
challenging mixed discrete-continuous optimization problem. We propose an
algorithm to obtain an optimal solution with reduced computational complexity
by exploiting optimality properties. To further reduce computational
complexity, we also propose two low-complexity algorithms to obtain two
suboptimal solutions, based on continuous relaxation and Difference of Convex
(DC) programming, respectively. Finally, numerical results demonstrate the
advantage of the proposed solutions.Comment: 22 pages, 6 figures, to be published in GLOBECOM 201
Power Allocation and Scheduling for SWIPT Systems with Non-linear Energy Harvesting Model
In this paper, we design a resource allocation algorithm for multiuser
simultaneous wireless information and power transfer systems for a realistic
non-linear energy harvesting (EH) model. In particular, the algorithm design is
formulated as a non-convex optimization problem for the maximization of the
long-term average total harvested power at EH receivers subject to quality of
service requirements for information decoding receivers. To obtain a tractable
solution, we transform the corresponding non-convex sum-of-ratios objective
function into an equivalent objective function in parametric subtractive form.
This leads to a computationally efficient iterative resource allocation
algorithm. Numerical results reveal a significant performance gain that can be
achieved if the resource allocation algorithm design is based on the non-linear
EH model instead of the traditional linear model.Comment: Accepted for presentation at the IEEE ICC 201
5G green cellular networks considering power allocation schemes
It is important to assess the effect of transmit power allocation schemes on
the energy consumption on random cellular networks. The energy efficiency of 5G
green cellular networks with average and water-filling power allocation schemes
is studied in this paper. Based on the proposed interference and achievable
rate model, an energy efficiency model is proposed for MIMO random cellular
networks. Furthermore, the energy efficiency with average and water-filling
power allocation schemes are presented, respectively. Numerical results
indicate that the maximum limits of energy efficiency are always there for MIMO
random cellular networks with different intensity ratios of mobile stations
(MSs) to base stations (BSs) and channel conditions. Compared with the average
power allocation scheme, the water-filling scheme is shown to improve the
energy efficiency of MIMO random cellular networks when channel state
information (CSI) is attainable for both transmitters and receivers.Comment: 14 pages, 7 figure
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