1,940 research outputs found
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
Risk-Informed Interference Assessment for Shared Spectrum Bands: A Wi-Fi/LTE Coexistence Case Study
Interference evaluation is crucial when deciding whether and how wireless
technologies should operate. In this paper we demonstrate the benefit of
risk-informed interference assessment to aid spectrum regulators in making
decisions, and to readily convey engineering insight. Our contributions are: we
apply, for the first time, risk assessment to a problem of inter-technology
spectrum sharing, i.e. Wi-Fi/LTE in the 5 GHz unlicensed band, and we
demonstrate that this method comprehensively quantifies the interference
impact. We perform simulations with our newly publicly-available tool and we
consider throughput degradation and fairness metrics to assess the risk for
different network densities, numbers of channels, and deployment scenarios. Our
results show that no regulatory intervention is needed to ensure harmonious
technical Wi-Fi/LTE coexistence: for the typically large number of channels
available in the 5 GHz band, the risk for Wi-Fi from LTE is negligible,
rendering policy and engineering concerns largely moot. As an engineering
insight, Wi-Fi coexists better with itself in dense, but better with LTE, in
sparse deployments. Also, both main LTE-in-unlicensed variants coexist well
with Wi-Fi in general. For LTE intra-technology inter-operator coexistence,
both variants typically coexist well in the 5 GHz band, but for dense
deployments, implementing listen-before-talk causes less interference
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
Survey on wireless technology trade-offs for the industrial internet of things
Aside from vast deployment cost reduction, Industrial Wireless Sensor and Actuator Networks (IWSAN) introduce a new level of industrial connectivity. Wireless connection of sensors and actuators in industrial environments not only enables wireless monitoring and actuation, it also enables coordination of production stages, connecting mobile robots and autonomous transport vehicles, as well as localization and tracking of assets. All these opportunities already inspired the development of many wireless technologies in an effort to fully enable Industry 4.0. However, different technologies significantly differ in performance and capabilities, none being capable of supporting all industrial use cases. When designing a network solution, one must be aware of the capabilities and the trade-offs that prospective technologies have. This paper evaluates the technologies potentially suitable for IWSAN solutions covering an entire industrial site with limited infrastructure cost and discusses their trade-offs in an effort to provide information for choosing the most suitable technology for the use case of interest. The comparative discussion presented in this paper aims to enable engineers to choose the most suitable wireless technology for their specific IWSAN deployment
IEEE 802.11ax: challenges and requirements for future high efficiency wifi
The popularity of IEEE 802.11 based wireless local area networks (WLANs) has increased significantly in recent years because of their ability to provide increased mobility, flexibility, and ease of use, with reduced cost of installation and maintenance. This has resulted in massive WLAN deployment in geographically limited environments that encompass multiple overlapping basic service sets (OBSSs). In this article, we introduce IEEE 802.11ax, a new standard being developed by the IEEE 802.11 Working Group, which will enable efficient usage of spectrum along with an enhanced user experience. We expose advanced technological enhancements proposed to improve the efficiency within high density WLAN networks and explore the key challenges to the upcoming amendment.Peer ReviewedPostprint (author's final draft
Spectral Efficiency Improvements in HetNets by Exploiting Device-to-Device Communications
Next generation cellular networks require huge capacity, ubiquitous coverage and maximum energy efficiency. In order to meet these targets, Device-to-device (D2D) communication is being considered for future heterogeneous networks (HetNets). In this paper, we consider a three tier hierarchical HetNet by exploiting D2D communication in traditional HetNet. D2D communication is deployed within the HetNet where closely located mobile users are engaged in direct communication without routing the traffic through cellular access network. The proposed configuration mandates to reduce the interference offered by the resultant HetNet by reducing the transmitter-receiver distance and ensuring that the mobile users are transmitting with adaptive power subject to maintaining their desired link quality. In this context, we analyzed and compared the spectral efficiency improvements in hierarchical HetNet against traditional HetNet. Simulation results show that D2D communication offers much higher spectral efficiency as compared to traditional HetNet
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