Connect Magazine Report

Praxis
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8/2014
Battery Life
Competition
New smart phones usually have increased capabilities over
their predecessors. Does this decrease endurance? We decided to find out which phone has a longer battery life - an older model like a Samsung Galaxy S4 or the newer S5 model.
he annoying thing
about smartphones is
that each newer generation
has less battery life than its
predecessor.“ This is the typical opinion of our connect readers. And „Now
that smartphones can do
just about everything, it´s
time manufacturers start
improving the battery life.
Smartphones should last
for at least a week before
recharging, like in the old
days!“
So what is the true situation? Is there indeed reduced
battery life as phone displays
continue to get bigger and
include more and more features and functions? Or are
manufacturers actually developing better batteries and/or
better power efficiency so
that each new phone generation runs longer? With the
question of „old versus new“
on the agenda, we were delighted to get an offer from
mobile device user experience expert Spirent Communications (see the box
on page 58) to examine and
compare the differences in
battery life between two
Old versus new which phone runs
longer?
smartphones.
What could be more appropriate than to compare
the Samsung Galaxy S4 with
its successor model, the S5?
Both phones are widely acclaimed, sell very well, offer
modern technical features
and include leading functions. According to connect
testing, both phones are well
engineered so it is not likely
that one of them has a design
failure due to a bad day at
the production line.
Sophisticated Measurement
Methods
Spirent´s Quantum Battery
Life Measurement System
was chosen as the basis for
analysis (see box on page
57). Quantum can determine
the power consumption and
hence the battery life under a
variety of conditions, making the comparison between models easier. Three
typical scenarios were investigated. In the first case, the
Samsung competitors had to
stream a YouTube video.
This entailed a fairly constant connection with continual data transfer and placed
high demands on the processor and graphics card. A second and more dynamic case
which challenges the
Fotos: © Peter Fenyvesi (12)
T
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Praxis
processor involved surfing the
web using the phone´s browser.
The third case incorporated a
multi-service voice and data
application. In this scenario, a
virtual user initiates a download and after 20 seconds ma-
Surfing the web is
the number 1 battery life killer!
scenarios for smartphones.
Consisting of varying types of
traffic from short bursts to
long continuous transmissions, each usage scenario
places different demands on
the phone´s processor, graphics card and audio systems.
Moreover it is possible to determine battery life for particular user types by applying
different weightings to each
base usage scenario. For example, a „video addict“ could
be someone who spends a
high proportion (85%) of phone time streaming videos.
Other user types include a
„balanced user“ (33% video
streaming, 33% surfing, and
33% multi service) or a „social media maven“ (10% video,
80% surfer, 10% multi service) or perhaps a „business
user“ with 5%, 20%, 75%
phone usage. With these
weighted modes of usage it´s
possible to predict battery life
for each user type based on a
realistic set of assumptions.
protect against errors as well as
the repetition of lost data
From Video Addict to Business User
Streaming video, web browsing and multi-service usage
represent three typical usage
Coverage is a cruical factor
Apart from general operation
of a smartphone, there are also
several marginal factors which
affect power consumption.
Most experts agree that the coverage situation is a crucial
factor. At low levels of reception (from -100 to -85 dBm)
smartphones have to transmit
with full capacity. They will
require more time to receive
data due to increased coding to
The current drain (blue) and power consumption (green) differ markedly between the Galaxy S4 (lighter-colored curve) and the S5 (darker-colored curve).
Several recordings are necessary to get a reliable estimate of the mean.
Differences in coverage (poor, fair and good) are unmistakable.
The differences in battery life (measured in hours) between Galaxy S5 (dark
blue) and S4 (light blue) for different user scenarios is higher than expected.
The difference between the Galaxy S5 (dark blue) and its predecessor S4
(light blue) are less apparent in 4G mode than in 3G mode.
kes a phone call. This test
ends with the conclusion of
the call and the termination of
the download.
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For additional analysis of our video
test we use circular and rapidly rotating symbols to detect missing, frozen or impaired frames.
METHOD OF MEASUREMENT
Spirent used its Quantum System for all measurements.
The sophistication required to take realistic measurements of smartphone
power consumption can
be seen in the numerous
mobile applications and
services controlled by the
Quantum Mobile Software. This special software must first be installed on the smartphone
under investigation to
enable remote control of
the device.
Simulating User Activity
The Quantum Mobile software runs in the background emulating the activity of a normal user.
Using this approach, the
user scenario being tested
can be set to run automatically on the smartphone.
For example, in the web
browsing test the browser
window could be opened
and a particular web
address entered, with additional defined actions
once the web page had
loaded. The important
point is that the software
itself places minimal demands on the phone´s resources so as not to influence measurement results significantly. Just as
important are the standard settings of the
smartphone, since options
such as display brightness
and GPS functions etc.
can affect power consumption.
Besides the smartphone,
a notebook with the Quantum Desktop Software to
run the test scenarios is
used. This software monitors and coordinates the
measurement process
and creates the reports.
The Quantum Interface,
between the smartphone
and notebook, is responsible not only for the power supply but also for
measuring supply voltage
and current drain. It´s important that the Quantum
Interface is able to make
several thousand readings
per second because some
smartphone components
are capable of shutting off
within milliseconds. A precise measurement system
must gather this precise
information as well as the
peak consumption values
for short bursts of power.
The Other End in the
Cloud
Part of the service testing
set up is the other end of
the connection, the Quantum Cloud. In order to record power consumption
during a phone conversation, it is necessary to have a connecting number
to automatically receive
the call. Also uploading
and downloading requires
a server connection which
ideally should not be dependent on some arbitrary
platform, but should be
within the control of the
end user. This way it´s
possible to avoid false
readings due to disruptions at the other end of
the line.
The Quantum Battery Life Measurement System consists of a two channel
measurement probe (below) coupled to desktop software to measure power
consumption and control the data transfers with Quantum Cloud acting as a
server.
The Quantum System simultaneously captures the current flow between the
batteries and the supply port for a maximum of two smart phones. Up to
25,000 measurements per second for each device are possible.
Although the individual test scenarios run automatically once started, a
specialist is still required to set up and initiate the measurement process.
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Praxis
Spirent Communications
Spirent Communications is a worldwide acclaimed
telecommunication testing enterprise.
Originally founded in 1936 in London as Goodlife Electric Supplies and later changing its name to Spirent Communications
the company achieved an annual turnover of over 400 million
USD with around 1,500 employees by the year 2013. The company generates its turnover from three main business fields.
First, accounting for almost 50% of their turnover is the field of
Networks and Applications, which concentrates on the areas of
Ethernet, central data and cloud computing, applications and
security, test optimization and wireless infrastructure. Secondly,
Wireless & Service Experience includes everything to do with
terminal equipment, channel simulation, navigation and service
quality. And finally, there is the field of Service Assurance in
which testing of networks, network operations and customer
satisfaction are the main focus of attention.
packages, both of which increase power consumption.
The question of whether 3G
or 4G reception consumes
more power is not clear and
this was therefore examined
separately. The experts at Spirent investigated three user
scenarios, using two smart
phones with two mobile phone transmission standards under three different supply situations. Using received signal
measurement analysis, three
locations in the vicinity of
Munich were selected to provide the different coverage
situations. Apart from the external factors there were also
internal factors affecting measurements such as settings for
display brightness. Both phones were set for normal
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8/2014
lighting conditions. Also the
WLAN adapter was switched
on but remained disconnected.
Optimum Chip Components
for Better Video Streaming
GPS was the only function
during testing that was disabled. This is not normally the
case with smartphones but
since GPS tracking occurs
sporadically and requires large amounts of power, it would
have meant doing several involved measurement sets in
order to make the effect negligible. Fifteen repetitions of
each single measurement were sufficient to get a 95% statistically acceptable confidence interval. The results of
the study are therefore quite
reliable.
The bottom left bar graph
on page 56 points out how the
current drain between the two
models for different scenarios
compares with each other.
Although both smartphones
have almost identical OLED
Does LTE Really Consume More Power?
Apparently Not!
displays and batteries (S4: 5
inch and 2600 mAh; S5: 5.1
inch and 2800 mAh) there is a
marked difference in current
drain between the two. To the
satisfaction of those believers
in technological advancement
who are eager for noticeable
improvements in battery life,
here´s evidence that the S5 is
better than the S4. Amazingly
the graph shows that surfing
the web places the highest demand on the batteries. The
multi-service scenario seems
to take advantage of a switched off display during phone
conversations while with video streaming it appears that a
large portion of the video co-
Spirent expert Joao Cardoso (left) and Manfred Rösch (right) discuss the
measurement results together with connect’s reporter, Bernd Theiss (middle).
ding is now performed by
specially optimized chip
components. That saves a lot
of power when compared to
the computation task performed by a general purpose
processor.
Clear Result: The Galaxy S5
Lasts Longer!
The Galaxy S5 has between
37% and 60% better battery
life than the S4. The Galaxy
S5 has up to 40% less battery
life when web browsing as
compared to video streaming
or voice calling with data
transfers running in the background. The same measurements made with 3G gave
negligible differences compared with 4G. Although the
S4 lost a little battery life, the
S5 gained slightly in two of
the three categories. This can
be seen from the bottom right
bar graph on page 56. Overall
the Galaxy S5 not only provides longer battery life, but
there were noticeably smaller
fluctuations between measurements which indicate a hig-
Spirent’s Project Engineer and specialist for the Quantum system,
Joao Cardoso, performing a typical application test in office for
connect’s investigation.
mation not only for connect´s
test lab but also for our faith
in technological advancement.
higher figures than
Spirent´s, they should
consider the fact that
during connect´s testing, short spaces of
time were additioKey Account Manager Rösch (right) showing
connect’s reporter, Theiss the server room
nally taken into acwhere various testing is done.
counting for users to
supposedly read their
her standard of optimization. displays.
Regardless of the method
Should anyone comparing
the results wonder why of phone life measurement,
connect´s laboratory testing the Galaxy S5 offers roughly
using a manual method of 50% better battery life than
phone life measurement gave the S4. This is a clear confir-
Bernd Theiss
Measurement Results
User-TypE
Balanced
Samsung
Galaxy S4
Smartphone
Video-Addict
Samsung
Galaxy S5
Samsung
Galaxy S4
Samsung
Galaxy S5
Social-Media-Maven
Samsung
Galaxy S4
Samsung
Galaxy S5
Business-User
Samsung
Galaxy S4
Samsung
Galaxy S5
Weighting
Videostreaming
33,3%
85%
10%
5%
Webbrowsing
33,3%
10%
80%
20%
Multi-Service
33,3%
5%
10%
75%
Battery Performance 3G
Videostreaming(h)
1:36
2:36
4:00
6:30
0:30
0:48
0:12
0:24
Webbrowsing
(h)
1:00
1:18
0:18
0:24
2:18
3:06
0:36
0:48
Multi-Service
(h)
1:30
2:42
0:12
0:24
0:30
0:48
3:30
6:00
Total
(h)
4:06
6:36
4:30
7:18
3:18
4:42
4:18
7:12
Videostreaming(h)
1:42
2:18
4:18
6:00
0:30
0:42
0:18
0:24
Webbrowsing(h)
1:00
1:24
0:18
0:24
2:24
3:18
0:36
0:48
Multi-Service
(h)
1:36
2:30
0:12
0:24
0:30
0:48
3:30
5:36
Total (h)
4:18
6:12
4:48
6:48
3:24
4:48
4:24
6:48
4:12
6:24
4:39
7:03
3:21
4:45
4:21
7:00
Battery Performance 4G
Total Battery Performance
Advantage S5
52%
52%
42%
61%
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