112 research outputs found
UxNB-Enabled Cell-Free Massive MIMO with HAPS-Assisted Sub-THz Backhauling
In this paper, we propose a cell-free scheme for unmanned aerial vehicle
(UAV) base stations (BSs) to manage the severe intercell interference between
terrestrial users and UAV-BSs of neighboring cells. Since the cell-free scheme
requires enormous bandwidth for backhauling, we propose to use the
sub-terahertz (sub-THz) band for the backhaul links between UAV-BSs and central
processing unit (CPU). Also, because the sub-THz band requires a reliable
line-of-sight link, we propose to use a high altitude platform station (HAPS)
as a CPU. At the first time-slot of the proposed scheme, users send their
messages to UAVs at the sub-6 GHz band. The UAVs then apply match-filtering and
power allocation. At the second time-slot, at each UAV, orthogonal resource
blocks are allocated for each user at the sub-THz band, and the signals are
sent to the HAPS after analog beamforming. In the HAPS receiver, after analog
beamforming, the message of each user is decoded. We formulate an optimization
problem that maximizes the minimum signal-to-interference-plus-noise ratio of
users by finding the optimum allocated power as well as the optimum locations
of UAVs. Simulation results demonstrate the superiority of the proposed scheme
compared with aerial cellular and terrestrial cell-free baseline schemes.Comment: 32 pages, 13 figure
Full-Duplex Wireless for 6G: Progress Brings New Opportunities and Challenges
The use of in-band full-duplex (FD) enables nodes to simultaneously transmit
and receive on the same frequency band, which challenges the traditional
assumption in wireless network design. The full-duplex capability enhances
spectral efficiency and decreases latency, which are two key drivers pushing
the performance expectations of next-generation mobile networks. In less than
ten years, in-band FD has advanced from being demonstrated in research labs to
being implemented in standards and products, presenting new opportunities to
utilize its foundational concepts. Some of the most significant opportunities
include using FD to enable wireless networks to sense the physical environment,
integrate sensing and communication applications, develop integrated access and
backhaul solutions, and work with smart signal propagation environments powered
by reconfigurable intelligent surfaces. However, these new opportunities also
come with new challenges for large-scale commercial deployment of FD
technology, such as managing self-interference, combating cross-link
interference in multi-cell networks, and coexistence of dynamic time division
duplex, subband FD and FD networks.Comment: 21 pages, 15 figures, accepted to an IEEE Journa
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
D3.2 First performance results for multi -node/multi -antenna transmission technologies
This deliverable describes the current results of the multi-node/multi-antenna technologies
investigated within METIS and analyses the interactions within and outside Work Package 3.
Furthermore, it identifies the most promising technologies based on the current state of
obtained results. This document provides a brief overview of the results in its first part. The second part, namely the Appendix, further details the results, describes the simulation
alignment efforts conducted in the Work Package and the interaction of the Test Cases. The
results described here show that the investigations conducted in Work Package 3
are maturing resulting in valuable innovative solutions for future 5G systems.Fantini. R.; Santos, A.; De Carvalho, E.; Rajatheva, N.; Popovski, P.; Baracca, P.; Aziz, D.... (2014). D3.2 First performance results for multi -node/multi -antenna transmission technologies. http://hdl.handle.net/10251/7675
D 3. 3 Final performance results and consolidated view on the most promising multi -node/multi -antenna transmission technologies
This document provides the most recent updates on the technical contributions and research
challenges focused in WP3. Each Technology Component (TeC) has been evaluated
under possible uniform assessment framework of WP3 which is based on the simulation guidelines
of WP6. The performance assessment is supported by the simulation results which are in their
mature and stable state. An update on the Most Promising Technology Approaches (MPTAs)
and their associated TeCs is the main focus of this document. Based on the input of all the TeCs in WP3, a consolidated view of WP3 on the role of multinode/multi-antenna transmission
technologies in 5G systems has also been provided. This consolidated view is further
supported in this document by the presentation of the impact of MPTAs on METIS scenarios
and the addressed METIS goals.Aziz, D.; Baracca, P.; De Carvalho, E.; Fantini, R.; Rajatheva, N.; Popovski, P.; Sørensen, JH.... (2015). D 3. 3 Final performance results and consolidated view on the most promising multi -node/multi -antenna transmission technologies. http://hdl.handle.net/10251/7675
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