14,251 research outputs found
Modeling Cellular Networks in Fading Environments with Dominant Specular Components
Stochastic geometry (SG) has been widely accepted as a fundamental tool for
modeling and analyzing cellular networks. However, the fading models used with
SG analysis are mainly confined to the simplistic Rayleigh fading, which is
extended to the Nakagami-m fading in some special cases. However, neither the
Rayleigh nor the Nakagami-m accounts for dominant specular components (DSCs)
which may appear in realistic fading channels. In this paper, we present a
tractable model for cellular networks with generalized two-ray (GTR) fading
channel. The GTR fading explicitly accounts for two DSCs in addition to the
diffuse components and offers high flexibility to capture diverse fading
channels that appear in realistic outdoor/indoor wireless communication
scenarios. It also encompasses the famous Rayleigh and Rician fading as special
cases. To this end, the prominent effect of DSCs is highlighted in terms of
average spectral efficiency.Comment: IEEE ICC1
On Modeling Heterogeneous Wireless Networks Using Non-Poisson Point Processes
Future wireless networks are required to support 1000 times higher data rate,
than the current LTE standard. In order to meet the ever increasing demand, it
is inevitable that, future wireless networks will have to develop seamless
interconnection between multiple technologies. A manifestation of this idea is
the collaboration among different types of network tiers such as macro and
small cells, leading to the so-called heterogeneous networks (HetNets).
Researchers have used stochastic geometry to analyze such networks and
understand their real potential. Unsurprisingly, it has been revealed that
interference has a detrimental effect on performance, especially if not modeled
properly. Interference can be correlated in space and/or time, which has been
overlooked in the past. For instance, it is normally assumed that the nodes are
located completely independent of each other and follow a homogeneous Poisson
point process (PPP), which is not necessarily true in real networks since the
node locations are spatially dependent. In addition, the interference
correlation created by correlated stochastic processes has mostly been ignored.
To this end, we take a different approach in modeling the interference where we
use non-PPP, as well as we study the impact of spatial and temporal correlation
on the performance of HetNets. To illustrate the impact of correlation on
performance, we consider three case studies from real-life scenarios.
Specifically, we use massive multiple-input multiple-output (MIMO) to
understand the impact of spatial correlation; we use the random medium access
protocol to examine the temporal correlation; and we use cooperative relay
networks to illustrate the spatial-temporal correlation. We present several
numerical examples through which we demonstrate the impact of various
correlation types on the performance of HetNets.Comment: Submitted to IEEE Communications Magazin
Efficient Sum-of-Sinusoids based Spatial Consistency for the 3GPP New-Radio Channel Model
Spatial consistency was proposed in the 3GPP TR 38.901 channel model to
ensure that closely spaced mobile terminals have similar channels. Future
extensions of this model might incorporate mobility at both ends of the link.
This requires that all random variables in the model must be correlated in 3
(single-mobility) and up to 6 spatial dimensions (dual-mobility). Existing
filtering methods cannot be used due to the large requirements of memory and
computing time. The sum-of-sinusoids model promises to be an efficient
solution. To use it in the 3GPP channel model, we extended the existing model
to a higher number of spatial dimensions and propose a new method to calculate
the sinusoid coefficients in order to control the shape of the autocorrelation
function. The proposed method shows good results for 2, 3, and 6 dimensions and
achieves a four times better approximation accuracy compared to the existing
model. This provides a very efficient implementation of the 3GPP proposal and
enables the simulation of many communication scenarios that were thought to be
impossible to realize with geometry-based stochastic channel models
Resilience to time-correlated noise in quantum computation
Fault-tolerant quantum computation techniques rely on weakly correlated
noise. Here I show that it is enough to assume weak spatial correlations: time
correlations can take any form. In particular, single-shot error correction
techniques exhibit a noise threshold for quantum memories under spatially local
stochastic noise.Comment: 16 pages, v3: as accepted in journa
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