10 research outputs found
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A Dense Reference Network for Mass-Market Centimeter-Accurate Positioning
The quality of atmospheric corrections provided
by a dense reference network for centimeter-accurate carrierphase
differential GNSS (CDGNSS) positioning is investigated.
A dense reference network (less than 20 km inter-station distance)
offers significant benefits for mass-market users, enabling lowcost
(including single-frequency) CDGNSS positioning with rapid
integer ambiguity resolution. Precise positioning on a massmarket
platform would significantly influence the world economy,
ushering in a host of consumer-focused applications such as
globally-registered augmented and virtual reality and improved
all-weather safety and efficiency for intelligent transportation
systems, applications which have so far been hampered by the
several-meter-level errors in standard GNSS positioning. This
contribution examines CDGNSS integer ambiguity resolution
performance in terms of network correction uncertainty, and
network correction uncertainty, in turn, in terms of network
density. It considers the total error in network corrections: a
sum of ionospheric, tropospheric, and reference station multipath
components. The paper’s primary goal is to identify the network
density beyond which mass-market users would see no further
significant improvement in ambiguity resolution performance. It
finishes by describing development and deployment of a low-cost
dense reference network in Austin, Texas.Aerospace Engineering and Engineering Mechanic
Pairwise interaction processes for modeling cellular network topology
Abstract—In industry, cellular tower locations have primarily been modeled by a deterministic hexagonal grid. Since real deployments are rarely regular, the even spacing between nodes in the grid and constant Voronoi cell areas make the hexagonal grid unrealistic. In this paper we use tools from spatial statistics to show that a purely random node placement and a hexagonal grid distribution with the points perturbed also have unrealistic spatial relationships between nodes, and that pairwise interac-tions between nodes are necessary, and in most cases sufficient, for modeling spatial qualities of cellular networks. We detail the benefits of using pairwise point interactions in modeling both a coverage-centric tower deployment and a capacity-centric tower deployment. We propose using pairwise and saturated pairwise interaction point processes from the Gibbs process family of point processes: the Strauss Hardcore process for inhibitive point patterns and the Geyer Saturation process for clustered point patterns. Due to its relationship with the coverage areas, we also propose that the Voronoi cell area distribution can be used as a test statistic in general spatial modeling of cellular networks. I
LTE-ADVANCED AND 4G WIRELESS COMMUNICATIONS: PART 2 Heterogeneous Cellular Networks: From Theory to Practice
The proliferation of internet-connected mobile devices will continue to drive growth in data traffic in an exponential fashion, forcing network operators to dramatically increase the capacity of their networks. To do this cost-effectively, a paradigm shift in cellular network infrastructure deployment is occurring away from traditional (expensive) high-power tower-mounted base stations and towards heterogeneous elements. Examples of heterogeneous elements include microcells, picocells, femtocells, and distributed antenna systems (remote radio heads), which are distinguished by their transmit powers/coverage areas, physical size, backhaul, and propagation characteristics. This shift presents many opportunities for capacity improvement, and many new challenges to co-existence and network management. This article discusses new theoretical models for understanding the heterogeneous cellular networks of tomorrow, and the practical constraints and challenges that operators must tackle in order for these networks to reach their potential