Battery Life Competition

Transcription

1 Praxis 54 8/2014

2 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 or the newer S5 model. T 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 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 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) 55

3 Praxis Surfing the web is the number 1 battery life killer! 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 makes a phone call. This test ends with the conclusion of the call and the termination of the download. From Video Addict to Business User Streaming video, web browsing and multi-service usage represent three typical usage 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. 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 protect against errors as well as the repetition of lost data For additional analysis of our video test we use circular and rapidly rotating symbols to detect missing, frozen or impaired frames. The current drain (blue) and power consumption (green) differ markedly between the (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 (dark blue) and S4 (light blue) for different user scenarios is higher than expected. The difference between the (dark blue) and its predecessor S4 (light blue) are less apparent in 4G mode than in 3G mode. 56 8/2014

4 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. 57

5 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 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 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). 58 8/2014

6 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. Key Account Manager Rösch (right) showing connect s reporter, Theiss the server room where various testing is done. Clear Result: The Lasts Longer! The 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 not only provides longer battery life, but there were noticeably smaller fluctuations between measurements which indicate a higher standard of optimization. Should anyone comparing the results wonder why connect s laboratory testing using a manual method of phone life measurement gave Spirent s Project Engineer and specialist for the Quantum system, Joao Cardoso, performing a typical application test in office for connect s investigation. higher figures than Spirent s, they should consider the fact that during connect s testing, short spaces of time were additionally taken into accounting for users to supposedly read their displays. Regardless of the method of phone life measurement, the offers roughly 50% better battery life than the S4. This is a clear confirmation not only for connect s test lab but also for our faith in technological advancement. Bernd Theiss Measurement Results User-TypE Balanced Video-Addict Social-Media-Maven Business-User Smartphone 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% 59