2,588 research outputs found
On the Delay of Geographical Caching Methods in Two-Tiered Heterogeneous Networks
We consider a hierarchical network that consists of mobile users, a
two-tiered cellular network (namely small cells and macro cells) and central
routers, each of which follows a Poisson point process (PPP). In this scenario,
small cells with limited-capacity backhaul are able to cache content under a
given set of randomized caching policies and storage constraints. Moreover, we
consider three different content popularity models, namely fixed content
popularity, distance-dependent and load-dependent, in order to model the
spatio-temporal behavior of users' content request patterns. We derive
expressions for the average delay of users assuming perfect knowledge of
content popularity distributions and randomized caching policies. Although the
trend of the average delay for all three content popularity models is
essentially identical, our results show that the overall performance of
cached-enabled heterogeneous networks can be substantially improved, especially
under the load-dependent content popularity model.Comment: to be presented at IEEE SPAWC'2016, Edinburgh, U
Fundamentals of Inter-cell Overhead Signaling in Heterogeneous Cellular Networks
Heterogeneous base stations (e.g. picocells, microcells, femtocells and
distributed antennas) will become increasingly essential for cellular network
capacity and coverage. Up until now, little basic research has been done on the
fundamentals of managing so much infrastructure -- much of it unplanned --
together with the carefully planned macro-cellular network. Inter-cell
coordination is in principle an effective way of ensuring different
infrastructure components behave in a way that increases, rather than
decreases, the key quality of service (QoS) metrics. The success of such
coordination depends heavily on how the overhead is shared, and the rate and
delay of the overhead sharing. We develop a novel framework to quantify
overhead signaling for inter-cell coordination, which is usually ignored in
traditional 1-tier networks, and assumes even more importance in multi-tier
heterogeneous cellular networks (HCNs). We derive the overhead quality contour
for general K-tier HCNs -- the achievable set of overhead packet rate, size,
delay and outage probability -- in closed-form expressions or computable
integrals under general assumptions on overhead arrivals and different overhead
signaling methods (backhaul and/or wireless). The overhead quality contour is
further simplified for two widely used models of overhead arrivals: Poisson and
deterministic arrival process. This framework can be used in the design and
evaluation of any inter-cell coordination scheme. It also provides design
insights on backhaul and wireless overhead channels to handle specific overhead
signaling requirements.Comment: 21 pages, 9 figure
Analysis and Optimization of Cellular Network with Burst Traffic
In this paper, we analyze the performance of cellular networks and study the
optimal base station (BS) density to reduce the network power consumption. In
contrast to previous works with similar purpose, we consider Poisson traffic
for users' traffic model. In such situation, each BS can be viewed as M/G/1
queuing model. Based on theory of stochastic geometry, we analyze users'
signal-to-interference-plus-noise-ratio (SINR) and obtain the average
transmission time of each packet. While most of the previous works on SINR
analysis in academia considered full buffer traffic, our analysis provides a
basic framework to estimate the performance of cellular networks with burst
traffic. We find that the users' SINR depends on the average transmission
probability of BSs, which is defined by a nonlinear equation. As it is
difficult to obtain the closed-form solution, we solve this nonlinear equation
by bisection method. Besides, we formulate the optimization problem to minimize
the area power consumption. An iteration algorithm is proposed to derive the
local optimal BS density, and the numerical result shows that the proposed
algorithm can converge to the global optimal BS density. At the end, the impact
of BS density on users' SINR and average packet delay will be discussed.Comment: This paper has been withdrawn by the author due to missuse of queue
model in Section Fou
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