The document summarizes a study comparing the battery life of the Samsung Galaxy S4 and S5 smartphones. Spirent Communications used their Quantum Battery Life Measurement System to test the phones under different usage scenarios like video streaming, web browsing, and multi-service tasks. The Galaxy S5 was found to have 37-60% better battery life than the S4 across all scenarios. Specifically, the S5 lasted over 50% longer than the S4 on average. The study concluded the S5 shows improvements in power optimization and battery life over its predecessor.

1. Praxis
8/201454

2. Battery Life
Competition
New smart phones usually have increased capabilities over
their predecessors. Does this decrease endurance? We deci-
ded to find out which phone has a longer battery life - an ol-
der 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 ty-
pical opinion of our con-
nect 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 situati-
on? Is there indeed reduced
battery life as phone displays
continue to get bigger and
include more and more fea-
tures and functions? Or are
manufacturers actually deve-
loping better batteries and/or
better power efficiency so
that each new phone genera-
tion runs longer? With the
question of „old versus new“
on the agenda, we were de-
lighted to get an offer from
mobile device user experi-
ence expert Spirent Com-
munications (see the box
on page 58) to examine and
compare the differences in
battery life between two
smartphones.
What could be more ap-
propriate than to compare
the Samsung Galaxy S4 with
its successor model, the S5?
Both phones are widely ac-
claimed, sell very well, offer
modern technical features
and include leading func-
tions. 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, ma-
king the comparison bet-
ween models easier. Three
typical scenarios were inves-
tigated. In the first case, the
Samsung competitors had to
stream a YouTube video.
This entailed a fairly cons-
tant connection with conti-
nual data transfer and placed
high demands on the proces-
sor and graphics card. A se-
cond and more dynamic case
which challenges the
T
Old versus new -
which phone runs
longer?
Fotos:©PeterFenyvesi(12)
55

3. The current drain (blue) and power consumption (green) differ markedly bet-
ween 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.
„balanced user“ (33% video
streaming, 33% surfing, and
33% multi service) or a „soci-
al media maven“ (10% video,
80% surfer, 10% multi ser-
vice) 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.
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 co-
verage situation is a crucial
factor.At low levels of recepti-
on (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
processor involved surfing the
web using the phone´s brow-
ser.
The third case incorporated a
multi-service voice and data
application. In this scenario, a
virtual user initiates a down-
load and after 20 seconds ma-
kes a phone call. This test
ends with the conclusion of
the call and the termination of
the download.
From Video Addict to Busi-
ness User
Streaming video, web brow-
sing and multi-service usage
represent three typical usage
scenarios for smartphones.
Consisting of varying types of
traffic from short bursts to
long continuous transmissi-
ons, each usage scenario
places different demands on
the phone´s processor, gra-
phics card and audio systems.
Moreover it is possible to de-
termine battery life for parti-
cular user types by applying
different weightings to each
base usage scenario. For ex-
ample, a „video addict“ could
be someone who spends a
high proportion (85%) of pho-
ne time streaming videos.
Other user types include a
protect against errors as well as
the repetition of lost data
For additional analysis of our video
test we use circular and rapidly rota-
ting symbols to detect missing, fro-
zen or impaired frames.
Surfing the web is
the number 1 batte-
ry life killer!
Praxis
56 8/2014

4. 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.
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.
Spirent used its Quantum System for all measurements.
METHOD OF MEASUREMENT
The sophistication requi-
red to take realistic mea-
surements of smartphone
power consumption can
be seen in the numerous
mobile applications and
services controlled by the
Quantum Mobile Soft-
ware. This special soft-
ware must first be ins-
talled on the smartphone
under investigation to
enable remote control of
the device.
Simulating User Activity
The Quantum Mobile soft-
ware runs in the back-
ground emulating the ac-
tivity of a normal user.
Using this approach, the
user scenario being tested
can be set to run automa-
tically on the smartphone.
For example, in the web
browsing test the browser
window could be opened
and a particular web
address entered, with ad-
ditional defined actions
once the web page had
loaded. The important
point is that the software
itself places minimal de-
mands on the phone´s re-
sources so as not to influ-
ence measurement re-
sults significantly. Just as
important are the stan-
dard settings of the
smartphone, since options
such as display brightness
and GPS functions etc.
can affect power con-
sumption.
Besides the smartphone,
a notebook with the Quan-
tum Desktop Software to
run the test scenarios is
used. This software moni-
tors and coordinates the
measurement process
and creates the reports.
The Quantum Interface,
between the smartphone
and notebook, is respon-
sible not only for the pow-
er supply but also for
measuring supply voltage
and current drain. It´s im-
portant 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 pre-
cise 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 Quan-
tum Cloud. In order to re-
cord power consumption
during a phone conversa-
tion, it is necessary to ha-
ve a connecting number
to automatically receive
the call. Also uploading
and downloading requires
a server connection which
ideally should not be de-
pendent 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 disrup-
tions at the other end of
the line.
57

5. Praxis
58 8/2014
packages, both of which incre-
ase 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 Spi-
rent investigated three user
scenarios, using two smart
phones with two mobile pho-
ne transmission standards un-
der three different supply situ-
ations. Using received signal
measurement analysis, three
locations in the vicinity of
Munich were selected to pro-
vide the different coverage
situations. Apart from the ex-
ternal factors there were also
internal factors affecting mea-
surements such as settings for
display brightness. Both pho-
nes were set for normal
Spirent Communications is a worldwide acclaimed
telecommunication testing enterprise.
Spirent Communications
Originally founded in 1936 in London as Goodlife Electric Sup-
plies 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 com-
pany 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.
lighting conditions. Also the
WLAN adapter was switched
on but remained disconnec-
ted.
Optimum Chip Components
for Better Video Streaming
GPS was the only function
during testing that was disab-
led. This is not normally the
case with smartphones but
since GPS tracking occurs
sporadically and requires lar-
ge amounts of power, it would
have meant doing several in-
volved measurement sets in
order to make the effect negli-
gible. Fifteen repetitions of
each single measurement we-
re sufficient to get a 95% sta-
tistically acceptable confi-
dence 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
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 de-
mand on the batteries. The
multi-service scenario seems
to take advantage of a swit-
ched off display during phone
conversations while with vi-
deo streaming it appears that a
large portion of the video co-
Does LTE Really Con-
sume More Power?
Apparently Not!
Spirent expert Joao Cardoso (left) and Manfred Rösch (right) discuss the
measurement results together with connect’s reporter, Bernd Theiss (middle).

6. 59
ding is now performed by
specially optimized chip
components. That saves a lot
of power when compared to
the computation task perfor-
med 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 back-
ground. The same measure-
ments made with 3G gave
negligible differences com-
pared 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 provi-
des longer battery life, but
there were noticeably smaller
fluctuations between measu-
rements which indicate a hig-
her standard of optimization.
Should anyone comparing
the results wonder why
connect´s laboratory testing
using a manual method of
phone life measurement gave
higher figures than
Spirent´s, they should
consider the fact that
during connect´s tes-
ting, short spaces of
time were additio-
nally taken into ac-
counting for users to
supposedly read their
displays.
Regardless of the method
of phone life measurement,
the Galaxy S5 offers roughly
50% better battery life than
the S4. This is a clear confir-
mation not only for connect´s
test lab but also for our faith
in technological advance-
ment.
Bernd Theiss
Key Account Manager Rösch (right) showing
connect’s reporter, Theiss the server room
where various testing is done.
Spirent’s Project Engineer and specialist for the Quantum system,
Joao Cardoso, performing a typical application test in office for
connect’s investigation.
User-TypE Balanced Video-Addict Social-Media-Maven Business-User
Smartphone
Samsung
Galaxy S4
Samsung
Galaxy S5
Samsung
Galaxy S4
Samsung
Galaxy S5
Samsung
Galaxy S4
Samsung
Galaxy S5
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
Battery Performance 4G
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
Total Battery Performance 4:12 6:24 4:39 7:03 3:21 4:45 4:21 7:00
Advantage S5 52% 52% 42% 61%
Measurement Results