Thesis Defense: Intelligent Network Selection and Energy Reduction for Mobile Devices

Speaker: Shuo Deng , CSAIL

Date: Thursday, April 30, 2015

Time: 2:00 PM to 4:00 PM Note: all times are in the Eastern Time Zone

Refreshments: 1:45 PM

Public: Yes

Location: 32-D463

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Host: Hari Balakrishnan, MIT - CSAIL

Contact: Sheila M. Marian, 617-253-1996, sheila@csail.mit.edu

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Reminders to: seminars@csail.mit.edu

Reminder Subject: TALK: Intelligent Network Selection and Energy Reduction for Mobile Devices

Abstract: The popularity of mobile devices has stimulated rapid progress in both Wi-Fi and cellular
technologies. Before LTE was widely deployed, Wi-Fi speeds dominated cellular network
speeds. But that is no longer true today: in a study we conducted with a crowd-sourced
measurement tool used by over 1,000 users in 16 countries, we found that 40% of the
time LTE outperforms Wi-Fi, and 75% of the time, the difference between LTE and Wi-Fi
throughput is higher than 1 Mbits/s.

Thus, instead of the currently popular “always prefer Wi-Fi” policy, we argue that mo-
bile devices should use the best available combination of networks: Wi-Fi, LTE or both.
Selecting the best network combination, however, is a challenging problem because: 1)
network conditions vary with both location and time, 2) many network transfers are short,
which means that the decision must be made with low overhead, and, 3) the best choice is
not only determined by best network performance, but also constrained by practical factors
such as monetary cost and battery life.

In this talk, we present Delphi, a software controller for network selection on mobile
devices. Delphi makes intelligent network selection decisions according to current network
conditions, monetary cost concerns, as well as battery-life considerations. Our experiments
show that Delphi reduces application network transfer time by 46% for Web browsing and
by 49% for video streaming, compared with Android’s default policy of always using Wi-Fi
when it is available. Delphi can also be configured to achieve high throughput while
being battery-efficient: in this configuration, it achieves 1.9x the throughput of Android’s
default policy while only consuming 6% more energy.

Delphi improves performance, but uses the cellular network more extensively than the
status quo, consuming more energy than before. To address this problem, we develop a
general method to reduce the energy consumption of cellular interfaces on mobile devices.
The key idea is to use the statistics of data transfers to determine the best times at which
to put the radio in different power states. These techniques not only make Delphi more
useful in practice, but can be deployed independently without Delphi, to improve energy
efficiency for any cellular network enabled devices. Experiments show that our techniques
reduces energy consumption by 15% - 60% across various traffic patterns.

Thesis Committee: Hari Balakrishnan, Dina Katabi, Sam Madden

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This event is not part of a series.

Created by Sheila M. Marian Email at Monday, April 27, 2015 at 1:47 PM.