1,602,782 research outputs found
Wi-Fi Coexistence with Duty Cycled LTE-U
Coexistence of Wi-Fi and LTE-Unlicensed (LTE-U) technologies has drawn
significant concern in industry. In this paper, we investigate the Wi-Fi
performance in the presence of duty cycle based LTE-U transmission on the same
channel. More specifically, one LTE-U cell and one Wi-Fi basic service set
(BSS) coexist by allowing LTE-U devices transmit their signals only in
predetermined duty cycles. Wi-Fi stations, on the other hand, simply contend
the shared channel using the distributed coordination function (DCF) protocol
without cooperation with the LTE-U system or prior knowledge about the duty
cycle period or duty cycle of LTE-U transmission. We define the fairness of the
above scheme as the difference between Wi-Fi performance loss ratio
(considering a defined reference performance) and the LTE-U duty cycle (or
function of LTE-U duty cycle). Depending on the interference to noise ratio
(INR) being above or below -62dbm, we classify the LTE-U interference as strong
or weak and establish mathematical models accordingly. The average throughput
and average service time of Wi-Fi are both formulated as functions of Wi-Fi and
LTE-U system parameters using probability theory. Lastly, we use the Monte
Carlo analysis to demonstrate the fairness of Wi-Fi and LTE-U air time sharing
LTE in Unlicensed Bands is neither Friend nor Foe to Wi-Fi
Proponents of deploying LTE in the 5 GHz band for providing additional
cellular network capacity have claimed that LTE would be a better neighbour to
Wi-Fi in the unlicensed band, than Wi-Fi is to itself. On the other side of the
debate, the Wi-Fi community has objected that LTE would be highly detrimental
to Wi-Fi network performance. However, there is a lack of transparent and
systematic engineering evidence supporting the contradicting claims of the two
camps, which is essential for ascertaining whether regulatory intervention is
in fact required to protect the Wi-Fi incumbent from the new LTE entrant. To
this end, we present a comprehensive coexistence study of Wi-Fi and
LTE-in-unlicensed, surveying a large parameter space of coexistence mechanisms
and a range of representative network densities and deployment scenarios. Our
results show that, typically, harmonious coexistence between Wi-Fi and LTE is
ensured by the large number of 5 GHz channels. For the worst-case scenario of
forced co-channel operation, LTE is sometimes a better neighbour to Wi-Fi -
when effective node density is low - but sometimes worse - when density is
high. We find that distributed interference coordination is only necessary to
prevent a "tragedy of the commons" in regimes where interference is very
likely. We also show that in practice it does not make a difference to the
incumbent what kind of coexistence mechanism is added to LTE-in-unlicensed, as
long as one is in place. We therefore conclude that LTE is neither friend nor
foe to Wi-Fi in the unlicensed bands in general. We submit that the systematic
engineering analysis exemplified by our case study is a best-practice approach
for supporting evidence-based rulemaking by the regulator.Comment: accepted for publication in IEEE Acces
Coordinated Dynamic Spectrum Management of LTE-U and Wi-Fi Networks
This paper investigates the co-existence of Wi-Fi and LTE in emerging
unlicensed frequency bands which are intended to accommodate multiple radio
access technologies. Wi-Fi and LTE are the two most prominent access
technologies being deployed today, motivating further study of the inter-system
interference arising in such shared spectrum scenarios as well as possible
techniques for enabling improved co-existence. An analytical model for
evaluating the baseline performance of co-existing Wi-Fi and LTE is developed
and used to obtain baseline performance measures. The results show that both
Wi-Fi and LTE networks cause significant interference to each other and that
the degradation is dependent on a number of factors such as power levels and
physical topology. The model-based results are partially validated via
experimental evaluations using USRP based SDR platforms on the ORBIT testbed.
Further, inter-network coordination with logically centralized radio resource
management across Wi-Fi and LTE systems is proposed as a possible solution for
improved co-existence. Numerical results are presented showing significant
gains in both Wi-Fi and LTE performance with the proposed inter-network
coordination approach.Comment: Accepted paper at IEEE DySPAN 201
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