6,609 research outputs found
2D Time-frequency interference modelling using stochastic geometry for performance evaluation in Low-Power Wide-Area Networks
In wireless networks, interferences between trans- missions are modelled
either in time or frequency domain. In this article, we jointly analyze
interferences in the time- frequency domain using a stochastic geometry model
assuming the total time-frequency resources to be a two-dimensional plane and
transmissions from Internet of Things (IoT) devices time- frequency patterns on
this plane. To evaluate the interference, we quantify the overlap between the
information packets: provided that the overlap is not too strong, the packets
are not necessarily lost due to capture effect. This flexible model can be used
for multiple medium access scenarios and is especially adapted to the random
time-frequency access schemes used in Low-Power Wide-Area Networks (LPWANs). By
characterizing the outage probability and throughput, our approach permits to
evaluate the performance of two representative LPWA technologies
Sigfox{\textsuperscript \textregistered} and LoRaWA{\textsuperscript
\textregistered}
Achieving Max-Min Throughput in LoRa Networks
With growing popularity, LoRa networks are pivotally enabling Long Range
connectivity to low-cost and power-constrained user equipments (UEs). Due to
its wide coverage area, a critical issue is to effectively allocate wireless
resources to support potentially massive UEs in the cell while resolving the
prominent near-far fairness problem for cell-edge UEs, which is challenging to
address due to the lack of tractable analytical model for the LoRa network and
its practical requirement for low-complexity and low-overhead design. To
achieve massive connectivity with fairness, we investigate the problem of
maximizing the minimum throughput of all UEs in the LoRa network, by jointly
designing high-level policies of spreading factor (SF) allocation, power
control, and duty cycle adjustment based only on average channel statistics and
spatial UE distribution. By leveraging on the Poisson rain model along with
tailored modifications to our considered LoRa network, we are able to account
for channel fading, aggregate interference and accurate packet overlapping, and
still obtain a tractable and yet accurate closed-form formula for the packet
success probability and hence throughput. We further propose an iterative
balancing (IB) method to allocate the SFs in the cell such that the overall
max-min throughput can be achieved within the considered time period and cell
area. Numerical results show that the proposed scheme with optimized design
greatly alleviates the near-far fairness issue, and significantly improves the
cell-edge throughput.Comment: 6 pages, 4 figures, published in Proc. International Conference on
Computing, Networking and Communications (ICNC), 2020. This paper proposes
stochastic-geometry based analytical framework for a single-cell LoRa
network, with joint optimization to achieve max-min throughput for the users.
Extended journal version for large-scale multi-cell LoRa network:
arXiv:2008.0743
Grant-free Radio Access IoT Networks: Scalability Analysis in Coexistence Scenarios
IoT networks with grant-free radio access, like SigFox and LoRa, offer
low-cost durable communications over unlicensed band. These networks are
becoming more and more popular due to the ever-increasing need for ultra
durable, in terms of battery lifetime, IoT networks. Most studies evaluate the
system performance assuming single radio access technology deployment. In this
paper, we study the impact of coexisting competing radio access technologies on
the system performance. Considering \mathpzc K technologies, defined by time
and frequency activity factors, bandwidth, and power, which share a set of
radio resources, we derive closed-form expressions for the successful
transmission probability, expected battery lifetime, and experienced delay as a
function of distance to the serving access point. Our analytical model, which
is validated by simulation results, provides a tool to evaluate the coexistence
scenarios and analyze how introduction of a new coexisting technology may
degrade the system performance in terms of success probability and battery
lifetime. We further investigate solutions in which this destructive effect
could be compensated, e.g., by densifying the network to a certain extent and
utilizing joint reception
Analysis of LoRaWAN Uplink with Multiple Demodulating Paths and Capture Effect
Low power wide area networks (LPWANs), such as the ones based on the LoRaWAN
protocol, are seen as enablers of large number of IoT applications and
services. In this work, we assess the scalability of LoRaWAN by analyzing the
frame success probability (FSP) of a LoRa frame while taking into account the
capture effect and the number of parallel demodulation paths of the receiving
gateway. We have based our model on the commonly used {SX1301 gateway chipset},
which is capable of demodulating {up to} eight frames simultaneously; however,
the results of the model can be generalized to architectures with arbitrary
number of demodulation paths. We have also introduced and investigated {three}
policies for Spreading Factor (SF) allocation. Each policy is evaluated in
terms of coverage {probability}, {FSP}, and {throughput}. The overall
conclusion is that the presence of multiple demodulation paths introduces a
significant change in the analysis and performance of the LoRa random access
schemes
Modeling Heterogeneous Network Interference Using Poisson Point Processes
Cellular systems are becoming more heterogeneous with the introduction of low
power nodes including femtocells, relays, and distributed antennas.
Unfortunately, the resulting interference environment is also becoming more
complicated, making evaluation of different communication strategies
challenging in both analysis and simulation. Leveraging recent applications of
stochastic geometry to analyze cellular systems, this paper proposes to analyze
downlink performance in a fixed-size cell, which is inscribed within a weighted
Voronoi cell in a Poisson field of interferers. A nearest out-of-cell
interferer, out-of-cell interferers outside a guard region, and cross-tier
interference are included in the interference calculations. Bounding the
interference power as a function of distance from the cell center, the total
interference is characterized through its Laplace transform. An equivalent
marked process is proposed for the out-of-cell interference under additional
assumptions. To facilitate simplified calculations, the interference
distribution is approximated using the Gamma distribution with second order
moment matching. The Gamma approximation simplifies calculation of the success
probability and average rate, incorporates small-scale and large-scale fading,
and works with co-tier and cross-tier interference. Simulations show that the
proposed model provides a flexible way to characterize outage probability and
rate as a function of the distance to the cell edge.Comment: Submitted to the IEEE Transactions on Signal Processing, July 2012,
Revised December 201
State-of-the-art assessment of 5G mmWave communications
Deliverable D2.1 del proyecto 5GWirelessMain objective of the European 5Gwireless project, which is part of the H2020 Marie Slodowska-
Curie ITN (Innovative Training Networks) program resides in the training and involvement of young
researchers in the elaboration of future mobile communication networks, focusing on innovative
wireless technologies, heterogeneous network architectures, new topologies (including ultra-dense
deployments), and appropriate tools. The present Document D2.1 is the first deliverable of Work-
Package 2 (WP2) that is specifically devoted to the modeling of the millimeter-wave (mmWave)
propagation channels, and development of appropriate mmWave beamforming and signal
processing techniques. Deliver D2.1 gives a state-of-the-art on the mmWave channel measurement,
characterization and modeling; existing antenna array technologies, channel estimation and
precoding algorithms; proposed deployment and networking techniques; some performance
studies; as well as a review on the evaluation and analysis toolsPostprint (published version
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