WLAN Interface Management on Mobile Devices
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Date
2008-08-15T17:57:39Z
Authors
Falaki, Mohammad Hossein
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
The number of smartphones in use is overwhelmingly increasing every year.
These devices rely on connectivity to the Internet for the majority of
their applications. The ever-increasing number of deployed 802.11 wireless
access points and the relatively high cost of other data services make the
case for opportunistic communication using free WiFi hot-spots. However,
this requires effective management of the WLAN interface, because by
design the energy cost of WLAN scanning and interface idle operation is
high and energy is a primary resource on mobile devices.
This thesis studies the WLAN interface management problem on mobile
devices. First, I consider the hypothetical scenario where future
knowledge of wireless connectivity opportunities is available, and present
a dynamic programming algorithm that finds the optimal schedule for the
interface. In the absence of future knowledge, I propose several heuristic
strategies for interface management, and use real-world user traces to
evaluate and compare their performance against the optimal algorithm.
Trace-based simulations show that simple static scanning with a suitable
interval value is very effective for delay-tolerant, background
applications. I attribute the good performance of static scanning to the
power-law distribution of the length of the WiFi opportunities of
mobile users, and provide guidelines for choosing the scanning interval
based on the statistical properties of the traces. I improve the
performance of static scanning, by 46% on average, using a local cache of
previous scan results that takes advantage of the location hints provided
by the set of visible GSM cell towers.
Description
Keywords
scanning, WLAN, smartphone, opportunistic