4,375 research outputs found
Energy-Efficient NOMA Enabled Heterogeneous Cloud Radio Access Networks
Heterogeneous cloud radio access networks (H-CRANs) are envisioned to be
promising in the fifth generation (5G) wireless networks. H-CRANs enable users
to enjoy diverse services with high energy efficiency, high spectral
efficiency, and low-cost operation, which are achieved by using cloud computing
and virtualization techniques. However, H-CRANs face many technical challenges
due to massive user connectivity, increasingly severe spectrum scarcity and
energy-constrained devices. These challenges may significantly decrease the
quality of service of users if not properly tackled. Non-orthogonal multiple
access (NOMA) schemes exploit non-orthogonal resources to provide services for
multiple users and are receiving increasing attention for their potential of
improving spectral and energy efficiency in 5G networks. In this article a
framework for energy-efficient NOMA H-CRANs is presented. The enabling
technologies for NOMA H-CRANs are surveyed. Challenges to implement these
technologies and open issues are discussed. This article also presents the
performance evaluation on energy efficiency of H-CRANs with NOMA.Comment: This work has been accepted by IEEE Network. Pages 18, Figure
Spectral Efficient and Energy Aware Clustering in Cellular Networks
The current and envisaged increase of cellular traffic poses new challenges
to Mobile Network Operators (MNO), who must densify their Radio Access Networks
(RAN) while maintaining low Capital Expenditure and Operational Expenditure to
ensure long-term sustainability. In this context, this paper analyses optimal
clustering solutions based on Device-to-Device (D2D) communications to mitigate
partially or completely the need for MNOs to carry out extremely dense RAN
deployments. Specifically, a low complexity algorithm that enables the creation
of spectral efficient clusters among users from different cells, denoted as
enhanced Clustering Optimization for Resources' Efficiency (eCORE) is
presented. Due to the imbalance between uplink and downlink traffic, a
complementary algorithm, known as Clustering algorithm for Load Balancing
(CaLB), is also proposed to create non-spectral efficient clusters when they
result in a capacity increase. Finally, in order to alleviate the energy
overconsumption suffered by cluster heads, the Clustering Energy Efficient
algorithm (CEEa) is also designed to manage the trade-off between the capacity
enhancement and the early battery drain of some users. Results show that the
proposed algorithms increase the network capacity and outperform existing
solutions, while, at the same time, CEEa is able to handle the cluster heads
energy overconsumption
Millimeter Wave Cellular Networks: A MAC Layer Perspective
The millimeter wave (mmWave) frequency band is seen as a key enabler of
multi-gigabit wireless access in future cellular networks. In order to overcome
the propagation challenges, mmWave systems use a large number of antenna
elements both at the base station and at the user equipment, which lead to high
directivity gains, fully-directional communications, and possible noise-limited
operations. The fundamental differences between mmWave networks and traditional
ones challenge the classical design constraints, objectives, and available
degrees of freedom. This paper addresses the implications that highly
directional communication has on the design of an efficient medium access
control (MAC) layer. The paper discusses key MAC layer issues, such as
synchronization, random access, handover, channelization, interference
management, scheduling, and association. The paper provides an integrated view
on MAC layer issues for cellular networks, identifies new challenges and
tradeoffs, and provides novel insights and solution approaches.Comment: 21 pages, 9 figures, 2 tables, to appear in IEEE Transactions on
Communication
Energy-Aware Wireless Relay Selection in Load-Coupled OFDMA Cellular Networks
We investigate transmission energy minimization via optimizing wireless relay
selection in orthogonal-frequency-division multiple access (OFDMA) networks. We
take into account the impact of the load of cells on transmission energy. We
prove the NP-hardness of the energy-aware wireless relay selection problem. To
tackle the computational complexity, a partial optimality condition is derived
for providing insights in respect of designing an effective and efficient
algorithm. Numerical results show that the resulting algorithm achieves high
energy performance.Comment: 4 pages, 2 figure
Study on Energy Consumption and Coverage of Hierarchical Cooperation of Small Cell Base Stations in Heterogeneous Networks
The demand for communication services in the era of intelligent terminals is
unprecedented and huge. To meet such development, modern wireless
communications must provide higher quality services with higher energy
efficiency in terms of system capacity and quality of service (QoS), which
could be achieved by the high-speed data rate, the wider coverage and the
higher band utilization. In this paper, we propose a way to offload users from
a macro base station(MBS) with a hierarchical distribution of small cell base
stations(SBS). The connection probability is the key indicator of the
implementation of the unload operation. Furthermore, we measure the service
performance of the system by finding the conditional probability-coverage
probability with the certain SNR threshold as the condition, that is, the
probability of obtaining the minimum communication quality when the different
base stations are connected to the user. Then, user-centered total energy
consumption of the system is respectively obtained when the macro base
station(MBS) and the small cell base stations(SBS) serve each of the users. The
simulation results show that the hierarchical SBS cooperation in heterogeneous
networks can provide a higher system total coverage probability for the system
with a lower overall system energy consumption than MBS.Comment: 6 pages, 7 figures, accepted by ICACT201
- …