990 research outputs found
LTE and Wi-Fi Coexistence in Unlicensed Spectrum with Application to Smart Grid: A Review
Long Term Evolution (LTE) is expanding its utilization in unlicensed band by
deploying LTE Unlicensed (LTEU) and Licensed Assisted Access LTE (LTE-LAA)
technology. Smart Grid can take the advantages of unlicensed bands for
achieving two-way communication between smart meters and utility data centers
by using LTE-U/LTE-LAA. However, both schemes must co-exist with the incumbent
Wi-Fi system. In this paper, several co-existence schemes of Wi-Fi and LTE
technology is comprehensively reviewed. The challenges of deploying LTE and
Wi-Fi in the same band are clearly addressed based on the papers reviewed.
Solution procedures and techniques to resolve the challenging issues are
discussed in a short manner. The performance of various network architectures
such as listenbefore- talk (LBT) based LTE, carrier sense multiple access with
collision avoidance (CSMA/CA) based Wi-Fi is briefly compared. Finally, an
attempt is made to implement these proposed LTEWi- Fi models in smart grid
technology.Comment: submitted in 2018 IEEE PES T&
Survey of Spectrum Sharing for Inter-Technology Coexistence
Increasing capacity demands in emerging wireless technologies are expected to
be met by network densification and spectrum bands open to multiple
technologies. These will, in turn, increase the level of interference and also
result in more complex inter-technology interactions, which will need to be
managed through spectrum sharing mechanisms. Consequently, novel spectrum
sharing mechanisms should be designed to allow spectrum access for multiple
technologies, while efficiently utilizing the spectrum resources overall.
Importantly, it is not trivial to design such efficient mechanisms, not only
due to technical aspects, but also due to regulatory and business model
constraints. In this survey we address spectrum sharing mechanisms for wireless
inter-technology coexistence by means of a technology circle that incorporates
in a unified, system-level view the technical and non-technical aspects. We
thus systematically explore the spectrum sharing design space consisting of
parameters at different layers. Using this framework, we present a literature
review on inter-technology coexistence with a focus on wireless technologies
with equal spectrum access rights, i.e. (i) primary/primary, (ii)
secondary/secondary, and (iii) technologies operating in a spectrum commons.
Moreover, we reflect on our literature review to identify possible spectrum
sharing design solutions and performance evaluation approaches useful for
future coexistence cases. Finally, we discuss spectrum sharing design
challenges and suggest future research directions
ORLA/OLAA: Orthogonal Coexistence of LAA and WiFi in Unlicensed Spectrum
Future mobile networks will exploit unlicensed spectrum to boost capacity and
meet growing user demands cost-effectively. The 3GPP has recently defined a
Licensed-Assisted Access (LAA) scheme to enable global Unlicensed LTE (U-LTE)
deployment, aiming at () ensuring fair coexistence with incumbent WiFi
networks, i.e., impacting on their performance no more than another WiFi
device, and () achieving superior airtime efficiency as compared to WiFi.
In this paper we show the standardized LAA fails to simultaneously fulfill
these objectives, and design an alternative orthogonal (collision-free)
listen-before-talk coexistence paradigm that provides a substantial improvement
in performance, yet imposes no penalty on existing WiFi networks. We derive two
LAA optimal transmission policies, ORLA and OLAA, that maximize LAA throughput
in both asynchronous and synchronous (i.e., with alignment to licensed anchor
frame boundaries) modes of operation, respectively. We present a comprehensive
performance evaluation through which we demonstrate that, when aggregating
packets, IEEE 802.11ac WiFi can be more efficient than 3GPP LAA, whereas our
proposals can attain 100% higher throughput, without harming WiFi. We further
show that long U-LTE frames incur up to 92% throughput losses on WiFi when
using 3GPP LAA, whilst ORLA/OLAA sustain 200% gains at no cost, even in the
presence of non-saturated WiFi and/or in multi-rate scenarios.Comment: 14 pages, 7 figures, submitted to IEEE/ACM Transactions on Networkin
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