2,628 research outputs found
5GNOW: Challenging the LTE Design Paradigms of Orthogonality and Synchronicity
LTE and LTE-Advanced have been optimized to deliver high bandwidth pipes to
wireless users. The transport mechanisms have been tailored to maximize single
cell performance by enforcing strict synchronism and orthogonality within a
single cell and within a single contiguous frequency band. Various emerging
trends reveal major shortcomings of those design criteria: 1) The fraction of
machine-type-communications (MTC) is growing fast. Transmissions of this kind
are suffering from the bulky procedures necessary to ensure strict synchronism.
2) Collaborative schemes have been introduced to boost capacity and coverage
(CoMP), and wireless networks are becoming more and more heterogeneous
following the non-uniform distribution of users. Tremendous efforts must be
spent to collect the gains and to manage such systems under the premise of
strict synchronism and orthogonality. 3) The advent of the Digital Agenda and
the introduction of carrier aggregation are forcing the transmission systems to
deal with fragmented spectrum. 5GNOW is an European research project supported
by the European Commission within FP7 ICT Call 8. It will question the design
targets of LTE and LTE-Advanced having these shortcomings in mind and the
obedience to strict synchronism and orthogonality will be challenged. It will
develop new PHY and MAC layer concepts being better suited to meet the upcoming
needs with respect to service variety and heterogeneous transmission setups.
Wireless transmission networks following the outcomes of 5GNOW will be better
suited to meet the manifoldness of services, device classes and transmission
setups present in envisioned future scenarios like smart cities. The
integration of systems relying heavily on MTC into the communication network
will be eased. The per-user experience will be more uniform and satisfying. To
ensure this 5GNOW will contribute to upcoming 5G standardization.Comment: Submitted to Workshop on Mobile and Wireless Communication Systems
for 2020 and beyond (at IEEE VTC 2013, Spring
Improved Handover Through Dual Connectivity in 5G mmWave Mobile Networks
The millimeter wave (mmWave) bands offer the possibility of orders of
magnitude greater throughput for fifth generation (5G) cellular systems.
However, since mmWave signals are highly susceptible to blockage, channel
quality on any one mmWave link can be extremely intermittent. This paper
implements a novel dual connectivity protocol that enables mobile user
equipment (UE) devices to maintain physical layer connections to 4G and 5G
cells simultaneously. A novel uplink control signaling system combined with a
local coordinator enables rapid path switching in the event of failures on any
one link. This paper provides the first comprehensive end-to-end evaluation of
handover mechanisms in mmWave cellular systems. The simulation framework
includes detailed measurement-based channel models to realistically capture
spatial dynamics of blocking events, as well as the full details of MAC, RLC
and transport protocols. Compared to conventional handover mechanisms, the
study reveals significant benefits of the proposed method under several
metrics.Comment: 16 pages, 13 figures, to appear on the 2017 IEEE JSAC Special Issue
on Millimeter Wave Communications for Future Mobile Network
An Efficient Uplink Multi-Connectivity Scheme for 5G mmWave Control Plane Applications
The millimeter wave (mmWave) frequencies offer the potential of orders of
magnitude increases in capacity for next-generation cellular systems. However,
links in mmWave networks are susceptible to blockage and may suffer from rapid
variations in quality. Connectivity to multiple cells - at mmWave and/or
traditional frequencies - is considered essential for robust communication. One
of the challenges in supporting multi-connectivity in mmWaves is the
requirement for the network to track the direction of each link in addition to
its power and timing. To address this challenge, we implement a novel uplink
measurement system that, with the joint help of a local coordinator operating
in the legacy band, guarantees continuous monitoring of the channel propagation
conditions and allows for the design of efficient control plane applications,
including handover, beam tracking and initial access. We show that an
uplink-based multi-connectivity approach enables less consuming, better
performing, faster and more stable cell selection and scheduling decisions with
respect to a traditional downlink-based standalone scheme. Moreover, we argue
that the presented framework guarantees (i) efficient tracking of the user in
the presence of the channel dynamics expected at mmWaves, and (ii) fast
reaction to situations in which the primary propagation path is blocked or not
available.Comment: Submitted for publication in IEEE Transactions on Wireless
Communications (TWC
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