18,734 research outputs found
IMPACT: Investigation of Mobile-user Patterns Across University Campuses using WLAN Trace Analysis
We conduct the most comprehensive study of WLAN traces to date. Measurements
collected from four major university campuses are analyzed with the aim of
developing fundamental understanding of realistic user behavior in wireless
networks. Both individual user and inter-node (group) behaviors are
investigated and two classes of metrics are devised to capture the underlying
structure of such behaviors.
For individual user behavior we observe distinct patterns in which most users
are 'on' for a small fraction of the time, the number of access points visited
is very small and the overall on-line user mobility is quite low. We clearly
identify categories of heavy and light users. In general, users exhibit high
degree of similarity over days and weeks.
For group behavior, we define metrics for encounter patterns and friendship.
Surprisingly, we find that a user, on average, encounters less than 6% of the
network user population within a month, and that encounter and friendship
relations are highly asymmetric. We establish that number of encounters follows
a biPareto distribution, while friendship indexes follow an exponential
distribution. We capture the encounter graph using a small world model, the
characteristics of which reach steady state after only one day.
We hope for our study to have a great impact on realistic modeling of network
usage and mobility patterns in wireless networks.Comment: 16 pages, 31 figure
Offloading traffic hotspots using moving small cells
In this paper, the concept of moving small cells in mobile networks is
presented and evaluated taking into account the dynamics of the system. We
consider a small cell moving according to a Manhattan mobility model which is
the case when the small cell is deployed on the top of a bus following a
predefined trajectory in areas which are generally crowded. Taking into account
the distribution of user locations, we study the dynamic level considering a
queuing model composed of multi-class Processor Sharing queues. Macro and small
cells are assumed to be operating in the same bandwidth. Consequently, they are
coupled due to the mutual interferences generated by each cell to the other.
Our results show that deploying moving small cells could be an efficient
solution to offload traffic hotspots.Comment: This article is already published in IEEE ICC conference 2016, Kuala
Lumpur, Wireless networks symposiu
On the Minimization of Handover Decision Instability in Wireless Local Area Networks
This paper addresses handover decision instability which impacts negatively
on both user perception and network performances. To this aim, a new technique
called The HandOver Decision STAbility Technique (HODSTAT) is proposed for
horizontal handover in Wireless Local Area Networks (WLAN) based on IEEE
802.11standard. HODSTAT is based on a hysteresis margin analysis that, combined
with a utilitybased function, evaluates the need for the handover and
determines if the handover is needed or avoided. Indeed, if a Mobile Terminal
(MT) only transiently hands over to a better network, the gain from using this
new network may be diminished by the handover overhead and short usage
duration. The approach that we adopt throughout this article aims at reducing
the minimum handover occurrence that leads to the interruption of network
connectivity (this is due to the nature of handover in WLAN which is a break
before make which causes additional delay and packet loss). To this end, MT
rather performs a handover only if the connectivity of the current network is
threatened or if the performance of a neighboring network is really better
comparing the current one with a hysteresis margin. This hysteresis should make
a tradeoff between handover occurrence and the necessity to change the current
network of attachment. Our extensive simulation results show that our proposed
algorithm outperforms other decision stability approaches for handover decision
algorithm.Comment: 13 Pages, IJWM
Improved Handover Through Dual Connectivity in 5G mmWave Mobile Networks
The millimeter wave (mmWave) bands offer the possibility of orders of
magnitude greater throughput for fifth generation (5G) cellular systems.
However, since mmWave signals are highly susceptible to blockage, channel
quality on any one mmWave link can be extremely intermittent. This paper
implements a novel dual connectivity protocol that enables mobile user
equipment (UE) devices to maintain physical layer connections to 4G and 5G
cells simultaneously. A novel uplink control signaling system combined with a
local coordinator enables rapid path switching in the event of failures on any
one link. This paper provides the first comprehensive end-to-end evaluation of
handover mechanisms in mmWave cellular systems. The simulation framework
includes detailed measurement-based channel models to realistically capture
spatial dynamics of blocking events, as well as the full details of MAC, RLC
and transport protocols. Compared to conventional handover mechanisms, the
study reveals significant benefits of the proposed method under several
metrics.Comment: 16 pages, 13 figures, to appear on the 2017 IEEE JSAC Special Issue
on Millimeter Wave Communications for Future Mobile Network
- …