1,857 research outputs found
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
Hybrid Spectrum Sharing in mmWave Cellular Networks
While spectrum at millimeter wave (mmWave) frequencies is less scarce than at
traditional frequencies below 6 GHz, still it is not unlimited, in particular
if we consider the requirements from other services using the same band and the
need to license mmWave bands to multiple mobile operators. Therefore, an
efficient spectrum access scheme is critical to harvest the maximum benefit
from emerging mmWave technologies. In this paper, we introduce a new hybrid
spectrum access scheme for mmWave networks, where data is aggregated through
two mmWave carriers with different characteristics. In particular, we consider
the case of a hybrid spectrum scheme between a mmWave band with exclusive
access and a mmWave band where spectrum is pooled between multiple operators.
To the best of our knowledge, this is the first study proposing hybrid spectrum
access for mmWave networks and providing a quantitative assessment of its
benefits. Our results show that this approach provides major advantages with
respect to traditional fully licensed or fully unlicensed spectrum access
schemes, though further work is needed to achieve a more complete understanding
of both technical and non technical implications
Understanding Noise and Interference Regimes in 5G Millimeter-Wave Cellular Networks
With the severe spectrum shortage in conventional cellular bands,
millimeter-wave (mmWave) frequencies have been attracting growing attention for
next-generation micro- and picocellular wireless networks. A fundamental and
open question is whether mmWave cellular networks are likely to be noise- or
interference-limited. Identifying in which regime a network is operating is
critical for the design of MAC and physical-layer procedures and to provide
insights on how transmissions across cells should be coordinated to cope with
interference. This work uses the latest measurement-based statistical channel
models to accurately assess the Interference-to-Noise Ratio (INR) in a wide
range of deployment scenarios. In addition to cell density, we also study
antenna array size and antenna patterns, whose effects are critical in the
mmWave regime. The channel models also account for blockage, line-of-sight and
non-line-of-sight regimes as well as local scattering, that significantly
affect the level of spatial isolation
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