Envelope tracking might sound like a certified mail service, but it’s really a technology used to tame LTE’s normally power hungry ways. LTE is unique among cellular technologies in that its power levels rise and dip dramatically throughout the course of a transmission – think of an LTE signal like the wild crescendos and quiet interludes of classical music.

Envelope tracking closely matches the power fed into the radio with the power needed at given moment to transmit. The result is a highly efficient power supply that can reduce a phone’s power drain by as much as 25 percent over current 4G devices. Given the miserable battery life of first generation of LTE phones, a 25 percent improvement is nothing to scoff at, and once combined with other power-saving technologies such as integrated handset silicon as well as improved batteries, we’ll see phones that can go much longer between charges.

Quantance’s latest $12 million round is its Series D with all of its existing investors — TD Fund, Granite Ventures, InterWest Partners and DoCoMo Capital – chipping in. Quantance raised $30 million in its previous rounds, going all the way back to 2006, the last of which was an $11 million investment in 2011.

Related research and analysis from GigaOM Pro:
Subscriber content. Sign up for a free trial.

• Updated: Forecast: global mobile subscribers, 2010-2015
• The mobile backhaul market, 2011-2012: more innovation, greater competition
• Survey: How apps can solve photo management

Tests of MetroPCS’s new VoLTE service found that 4G calls drained twice as much as regular CDMA ones. At the time, however, Spirent Global Director of Insights Amit Malhotra predicted that VoLTE’s power efficiency would improve as both VoLTE network and handset technology progressed. Fast-forward four months and Malhotra’s prognostication appears to be coming true.

Spirent recently performed a new batch of tests using Metro’s newest generation VoLTE handset, the LG Spirit 4G, and found that the current drain from a VoLTE call had dropped by 35 percent compared to LG’s first-generation VoLTE smartphone, the Connect. Improving power efficiency by 35 percent is a tremendous number when it comes to cellular battery life, which tends to measure progress in tiny increments. But there is still one big qualification to that good news: 2G is still a more power-efficient technology.

With its latest generation handset, LG improved the overall radio performance of the phone by using an integrated CDMA-LTE radio, rather than the dual chips used in the older Connect (it also beefed up the Spirit with a much larger 2150 mAh battery). That resulted in an 18 percent current drain improvement for CDMA calls in addition to the improved performance in VoLTE. Even with its efficiency boost, VoLTE still ate up far more juice than a CDMA call on either the new Spirit or the old Connect.

Spirent’s tests concluded that the LG Spirit would support 875 minutes of talk time in CDMA mode, but only 575 minutes when solely making 4G calls. The Spirit’s bigger battery (with 38 percent more capacity than the Connect) gives the device a big boost in single-charge lifespan, but that 300-minute differential is still huge.

The bottom line is that while VoLTE’s battery drain is improving it still has a ways to go before it can match the power efficiency of 2G. CDMA and GSM technologies went through more than a decade of optimization to reach their current efficiency levels.  Hopefully VoLTE can close that gap in a much shorter interval. The big improvements LG and MetroPCS demonstrated in a single generation of handsets is a good sign that it can.

Correction: This post was updated at 11:30 AM, Tuesday, to correct a percentage. Spirent measured a 35 percent power drain improvement in VoLTE calls between the two generation of LG devices, not 33 percent.

Related research and analysis from GigaOM Pro:
Subscriber content. Sign up for a free trial.

• CES 2012: a recap and analysis
• Updated: Forecast: global mobile subscribers, 2010-2015
• Mobile 2012 and beyond

What’s interesting about Verizon’s approach is it isn’t making its recommendations based on how entertaining, useful or fun a particular app is. Instead a team of Verizon engineers is looking at each app’s impact on the phone’s battery life, its drain on a customer’s data plan and how loosely it plays with security and customer privacy.

Basically, Verizon is compiling a series of regularly updated recommendation lists. The first is a list of 20 apps available either for Android or iOS that Verizon claims deliver a “best in class” experience on smartphones and tablets. As you might expect, Verizon isn’t being entirely objective in its choices, but it never claimed to be. One of the apps is even Verizon’s own AppLuvr software, which recommends other apps based on what’s already installed on smartphones.

The second list applies a much more visible methodology, rating the top 25 free and top 25 paid apps in Google Play based on three criteria: security, battery consumption and data usage. The third set of reviews is essentially Verizon’s naughty list: 13 apps – all games – that will drain your battery or eat up your data plan at a rapid clip.

Verizon isn’t making any friends here among the game development shops. Enormously popular games like Halfbrick’s Fruit Ninja Free and OMGPOP’s Draw Something got bad marks because of their battery drain. Other apps like Facebook Messenger and eBay scored relatively high but were penalized because of their high data consumption.

That may come us a surprise to many users since Facebook and eBay wouldn’t appear to consume that much data, especially compared to streaming multimedia apps like Pandora and Netflix, which received the highest possible Verizon ratings. But what Verizon is likely highlighting here is the persistence of those two apps’ connections. While Facebook might consume only a tiny fraction of the data in a single hour than, say, a Netflix video stream, the social networking app is always running in the background – transmitting a constant stream of signaling traffic over the network and whittling away at your data plan.

Alcatel-Lucent recently analyzed the enormous impact Facebook has on mobile networks through that signaling traffic. On Nov. 15, the social networking giant updated its iOS and Android apps, precipitating a 60 percent boost in Facebook signal load on mobile networks, even though the number of new Facebook mobile users increased only 4 percent in the same time frame. Alcatel-Lucent now estimates that Facebook is responsible for more than 15 percent of all mobile signaling traffic and accounts for more than 20 percent of all network airtime.

Carriers have long implored developers to keep the constraints of mobile networks in mind and build more efficient apps. With these rankings Verizon could be upping that pressure, punishing developers who keep developing unnecessarily chatty software.

As you might expect, neither Facebook Messenger or the main Facebook app made Verizon’s list of “must have apps” (though eBay did). Verizon, however, named Facebook’s much more network-efficient Instagram photo-sharing app in its top 20. I doubt Facebook cares either way.

Any time a carrier produces a must-have list you should take it with a grain of salt, but I will give Verizon credit. It actually recommended Tango, an over-the-top voice, video and messaging app that competes directly with Verizon’s core voice and SMS services.

Related research and analysis from GigaOM Pro:
Subscriber content. Sign up for a free trial.

Metrico Wireless, a radio field testing company Spirent acquired in September, conducted voice trials on a commercial VoLTE-enabled network in two U.S. cities, comparing the power consumption of VoIP calls made over LTE against the power used by the same carrier’s CDMA systems. Spirent-Metrico didn’t name the carrier, but it’s not hard to guess.

MetroPCS is the only U.S. operator with a live VoLTE service and a commercially available handset. The 1540 milliamp hour (mAh)-battery on Metro’s sole VoLTE handset, the LG Connect 4G, also lines up with the battery capacity of the device Spirent tested.

The results of those tests should give carriers and consumers pause. The average power consumption for a 10-minute CDMA circuit-switched call was 680 milliwatts (mW) while the average consumption for a VoLTE call of the same duration was 1358 mW. That’s double the power drain. Spirent estimated that on a full charge, its test smartphone could support 502.6 minutes of talk time using CDMA only, but the same charge would only deliver 251.8 minutes of talk time using VoIP on the 4G network. And that’s with all other data communications turned off.

What it comes down to is that our old GSM and CDMA circuit-switched voice technologies — despite their limitations — have been optimized over the last two decadesto be energy efficient, Spirent Global Director of Insights Amit Malhotra told GigaOM in an email interview. It’s hard to replicate that kind of efficiency overnight in a generic data modem.

“The disadvantage in battery life of VoLTE compared to circuit-switched voice is driven by a few different factors,” Malhotra said. “One is the more strenuous exercise of the device, including conversion of voice to packet data, transmission and receipt over the data network, and reconversion back to voice. Another is the use of less power-efficient components such as data modems versus voice transceivers.”

If this proves to be typical for VoLTE handsets, it will be a big problem. The battery life of the first generation of LTE smartphones was atrocious, and handset vendors have tried to address the problem by slapping fat 3000+ mAh power cells onto their phones. Some carriers are already reluctant to embrace VoLTE since they can still squeeze plenty of life out of their 2G and 3G voice services. If VoLTE proves to be a battery killer, they will be even less inclined to move mobile voice into the IP age.

There is some good news in Spirent’s findings though. It found LTE performed better than CDMA when the phone is used to make simultaneous voice and data calls. When the phone was in 4G-only mode — i.e., using only the LTE network for both VoIP and data — it performed slightly more efficiently than when the 2G radio was used for voice while the 4G radio transmitted data, Spirent discovered. That makes sense since powering two radios simultaneously could take an enormous toll on battery life.

That would seem to indicate that if you tend to talk and consume data at the same time, then VoLTE is a more efficient technology. That’s true, but only to the tiniest degree. The study found that both in both scenarios the hyperactivity of the device drained tremendous amount of energy. Battery life estimates dropped below 120 minutes in both cases. No matter which radios you use, talking and surfing consumes a tremendous amount of power.

Malhotra, however, said LTE power efficiency is bound to improve as both data modem technology and network coverage gets better. Today’s LTE networks have limited footprints, forcing phones to continuously check for signals. Eventually the data modems in our handsets will be optimized for VoIP calling.

“These issues will be mitigated over time, especially as components continue to become more power efficient, and devices do not need to switch between different modes of voice call processing,” Malhotra said.

Related research and analysis from GigaOM Pro:
Subscriber content. Sign up for a free trial.

• CES 2012: a recap and analysis
• Updated: Forecast: global mobile subscribers, 2010-2015
• Mobile 2012 and beyond

The Quantance chip

Quantance’s LTE power boosting technology is now out of the labs and on its way to device manufacturers, the San Mateo, Calif., power supply startup said on Tuesday. It has begun shipping samples of its qBoost chips to handset makers and radio silicon vendors, but most significantly it claims to have landed its first customer.

CEO and co-founder Vikas Vinayak wouldn’t name the customer or any details of the deal, citing confidentiality agreements, but he said the commitment allows Quantance to begin ramping up production this year.

Quantance utilizes a technology called envelope tracking to overcome one of LTE’s biggest limitations, it’s high peak-to-average ratio, which sucks down battery power and limits talk and surf time on your smartphone. LTE is unique among radio interfaces in that it’s power levels rise and dip dramatically throughout a transmission, compared to less schizophrenic 3G and 2G technologies. Jeremy Hendy, a VP at competing power supply vendor Nujira, had an apt analogy: You can think of 3G and 2G technologies as heavy metal music – pretty much consistently loud – while LTE is like classical music with long moments of quiet punctuated with wild crescendos.

The end result is that LTE device amplifiers need to maintain a constant flow of power to account for those peaks even if most of the time the transmission requires far less energy, which is one of the biggest reasons LTE devices have such miserable battery life. What envelope tracking technologies do is wrap the transmission in the power equivalent of a latex bondage suit, constantly matching the wattage put out by the amp to the power required for the transmission.

Quantance claims its envelop tracking technology stands out due to its speed, switching between low and high power modes 100 times faster than its competitors’ chips. That allows Quantance to not only improve the battery efficiency – and thus battery life – of LTE handsets and tablets, but also optimize the LTE transmission, meaning more capacity and a more persistent link to the tower.

Quantance presented at GigaOM’s Mobilize conference last year, winning the awards for audience and judges’ favorites among 10 new startups at the conference’s Launchpad event. The company closed on an $11 million round of funding in September from the TD Fund, Granite Ventures, InterWest Partners and DOCOMO Capital.

Related research and analysis from GigaOM Pro:
Subscriber content. Sign up for a free trial.

• LTE-Advanced: what it is and isn’t
• Why tomorrow’s iPad will need a battery breakthrough
• LTE changes everything; LTE changes nothing

The San Diego-based wireless silicon vendor on Monday said it has acquired Summit Microelectronics for an undisclosed amount. Summit makes programmable chipsets designed to optimize power performance in portable electronics and networking infrastructure.

Based out of Sunnyvale, Calif., the company was formed in 1997 and was backed by August Capital, Bessemer Venture Partners, HLM Management, Norwest Venture Partners, Pequot Capital and Spinnaker Ventures. Summit has 50 employees, all of whom are joining Qualcomm’s ranks in its CDMA Technologies division, which is responsible for making the company’s core radio modems and Snapdragon application processors.

Battery technologies simply haven’t kept up with the power demands of smartphones, which has led manufacturers like Motorola and Nokia to stick larger and larger lithium-ion packs in their handsets to keep them running. Qualcomm didn’t explain exactly how it will integrate Summit’s technology into its chipsets, saying only the acquisition “enhances the competitiveness of Qualcomm’s chipset solutions and enables us to provide our customers with industry leading power management and charging performance.”

Related research and analysis from GigaOM Pro:
Subscriber content. Sign up for a free trial.

• CES 2012: a recap and analysis
• Analyzing the wearable computing market
• How to manage the signaling storm in 2013

I realized this after a training run on the roads yesterday. I ran a 7.25 miles in leisurely 61 minutes with my smartphone. When I left the house, I had a fully charged battery. At the completion of my run, the battery was down to 90 percent, so I used one-tenth of the battery in that hour. But with all of the sensors and functions going, I think the handset ran harder than I did.

During the run, I used a mobile application to monitor my pace, distance and location; the app was constantly updated by the phone’s sensors. Which ones? The GPS and Bluetooth radios were constantly feeding the app with key data. That includes my heart rate, which was tracked by low-power Bluetooth 4.0 chest strap. I also listened to music the entire time, with the volume level around 60 percent. Oh, and of course the cellular radio was active for voice and data, although I did turn off the Wi-Fi radio.

Think about that for a second. Between mobile apps, radios, sensors and even occasional screen wakes to see my progress, my phone was able to do a fair number of functions for the entire hour, using one-tenth of the battery capacity.

When I think back to the pre-smartphone days, I remember my PDA devices quickly drained the battery. Some of these had large screens — I bought one of the first color Pocket PCs a dozen years ago — perhaps a Wi-Fi radio and few other sensors or radios. And yet, I might have gotten two full days of battery life at that time, but generally had to charge my devices each night. That’s essentially no different that today.

But what is different is the number of sensors, features and functions found in the devices of today. We can do so much more on a single charge.

Instead of major battery advances, hardware makers have implemented highly integrated chips, such as silicon with 3G, 4G, Bluetooth, Wi-Fi and even FM radio support on a single chip, for example. Plus that Wi-Fi radio pulls double-duty: It’s now a gateway to share a mobile broadband connection with your other devices.

Display technology has improved too, using less power to backlight the screen even as we move to high-definition resolution. And software is far more optimized to work with the chips that power our phones and tablets. The processors on our chips are also smarter, ramping up in power as needed, but slowing down or offloading instructions for smaller or less-intensive tasks, which saves on power.

Sure, I’m just like everyone else and want to see a device that lasts for days on a charge. But I’ll happily take a handset that adds more radios or sensors without a major battery hit too. If I can get more “bang per watt” out of my mobile gadgets, I’m happy.

Related research and analysis from GigaOM Pro:
Subscriber content. Sign up for a free trial.

• Sector RoadMap: Social customer service in 2013
• Analyzing the wearable computing market
• Updated: Forecast: global mobile subscribers, 2010-2015

The good news is that handset makers and network vendors are doing plenty to boost the power efficiency of LTE devices, but the bad news is that as 4G technologies evolve, making our phone and tablet connections even faster, their radios will continue to voraciously eat up batteries. The question is can the former trend keep up with the latter.

Why your next LTE phone will be better

The first generation of LTE devices are unquestionable the most sophisticated smartphones and tablets we’ve seen to date in terms of processing power, screen-resolution and OS software. But the approach most vendors were forced to take to the radio was hardly delicate. In most cases an LTE chip was shoehorned into the device, which is hardly a formula for long battery life.

There’s a lot of work that silicon vendors are doing to squeeze better power performance out of those phones. Components that are today separated in the bowels of the phone such as the applications processor and baseband will be combined, allowing them to share power resources. The world’s largest radio chip vendor Qualcomm has released its first integrated Snapdragon processor and LTE radio modem, and according to Qualcomm product management VP Raj Talluri, we’ll see many devices supporting that next-gen chip at Mobile World Congress next week.

Texas Instruments is developing radio chips that require the device to lean less and less on a smartphone’s powerful applications processor to perform basic tasks, such as initiate NFC payments or perform quick GPS-location checks. The longer the apps processor remains dormant the less drain the phone will have on the battery.

Optimizing the network will also be a big source of power savings. As operators move their voice services onto LTE and build out both the coverage and density of their networks, they can offer LTE-only phones (Verizon is targeting its first such device for 2013). The fewer active radios there are sucking at the battery, the longer our phones will sustain charges.

As operators build denser networks, shrinking the size of LTE cells, phones won’t have to boost their transmit power as much to link to the tower. And as coverage improves, phones will stay within LTE’s warm embrace for longer intervals, eliminating the need to constantly negotiate between an operator’s multiple networks.

The tug-of-war in the handset

The big question is whether all of those tweaks and technologies will be enough. Power drain will be an ongoing problem for handset designers and their efforts are complicated by the fact that radios are becoming fundamentally less power efficient even as they become more bandwidth efficient. ABI Research analyst Jim Mielke summed up this way: “The bottom line is the higher the data rate and higher spectral efficiency, the higher the computing requirements — and thus power drain.”

That means future technologies like LTE-Advanced, which promises speeds as high 1 Gbps, will be ravenously hungry for power. Older generation technologies won’t be immune either. As T-Mobile moves to 84 Mbps HSPA+, it will add dual antennas to its devices, which suck down power just like their LTE brethren.

Mielke said some of that power drain is offset by the simple efficiency of its ultra-fast LTE modem  — the faster a device can download a video or file, the sooner it can shut down the data session and de-activate the radio. Theoretically faster download speeds and the LTE radio’s inherent power inefficiency should cancel each other out, but that’s assuming that consumers use LTE phones the same way they use 3G ones. It’s no coincidence that the newest smartphones don’t just have 4G radios, but also larger higher-definition screens and multi-core processors. LTE’s speeds allow the mobile public to do so much more with their handsets, and the tendency is take advantage of that raw power to stream more video, surf more Web pages and download more files – that is until data caps kick in.

Vendors like Motorola are combating the problem by sacrificing design for fatter batteries, as it did with the new Razr Maxx. The short term solution is for device makers to devote more device cost and space to the phone’s lithium-ion footprint. But ultimately battery technology is going to have to improve if the handset industry is going to keep up with advancements in radio technology.

Related research and analysis from GigaOM Pro:
Subscriber content. Sign up for a free trial.

• The big theme of MWC: How to live in a connected world
• LTE changes everything; LTE changes nothing
• How to manage the signaling storm in 2013

Why is LTE so greedy? For starters, the radio in your LTE device is doing a lot more than it ever did in your old 3G handset. The radio is the single biggest source of power drain in any device apart from the LED screen, but unlike the display, the radio is always on. And LTE is particularly hungry. The next time your new Galaxy Nexus or HTC Vivid conks out right after lunch, here are five reasons why:

• Your phone has rabbit ears. All LTE devices sold today use a technology called MIMO, which doesn’t just send or receive a single signal, but rather multiple parallel transmissions. Today’s devices support two such paths – future devices will support more — which means each phone has two antennas, each of which requires its own power amplifier. It’s not quite as bad as the running two phones off of a single battery, but you get the idea.

• Look at all those networks! Verizon Wireless and MetroPCS 4G phones aren’t just maintaining two LTE links, they’re running an additional radio to boot. Devices from these carriers have to remain in constant contact with both the CDMA network – to receive phone calls and texts – and the LTE network.

• LTE devices are co-dependent. Your screen may be dark, but your phone is constantly pining for the network. That means its periodically scans the airwaves around it to determine which tower it should tether itself to. The more networks there are to choose from the more scans it must make. With the typical operator sporting some combination of GSM, HSPA, CDMA and EV-DO systems — often multiple version of each in different frequency bands — there are a lot of other networks for an LTE device to flip between.

• Is that a tower on the horizon? Operators haven’t built out their new LTE footprints densely yet. With cells spaced much further apart, devices have to reach further – and thus boost their transmission power — to latch onto a tower. And since there are still plenty of coverage holes in these networks, phones are dropping in and out of LTE coverage quite often, initiating new rounds of scans and taxing the battery further.

• This ain’t no FM radio. There is a reason each generation of wireless technology is faster and more efficient than its predecessors. RF engineers are finding more and better ways to wrestle more bits into a radio wave. But, the more complex the waveform, the more computing power phone processors use up modulating and demodulating that radio wave. The 64-state quadrature amplitude modulation (QAM) and orthogonal frequency division multiplexing (OFDM) techniques used in LTE are as complicated as they sound. Consequently, the faster and more spectrally efficient networks become, the more power phones will consume trying to make sense of their signals.

So are we doomed forever to a life of constantly reaching for our battery chargers? On Monday, we’ll explore what handset makers and network suppliers are doing to improve LTE battery life, but also how they may be fighting a losing battle.

Tesla coil image courtesy of Flickr user caseyyee

Related research and analysis from GigaOM Pro:
Subscriber content. Sign up for a free trial.

• Mobile 2012 and beyond
• 12 tech leaders’ resolutions for 2012
• Mobile Q4: The scramble for spectrum continues

According to Northwestern’s Professor Harold Kung, the longer-lasting batteries take advantage of two new processes. First, the number of lithium-ion atoms in the battery’s electrode are boosted by using silicon in place of carbon between sheets of graphene in the battery. It sounds complicated, but the gist is this: Silicon works 24 times more efficiently with lithium ions compared to carbon, which is used in traditional batteries.

Second, the research team scored the graphine sheets with microscopic holes, allowing the lithium ions to travel faster within the battery. These techniques improve both the recharge time and density of lithium ions, which equates to longer-lasting batteries with fast recharge times, perhaps as little as 15 minutes. Kung explains the process as having “[T]he best of both worlds. We have much higher energy density because of the silicon, and the sandwiching reduces the capacity loss caused by the silicon expanding and contracting.”

Battery science hasn’t changed all that much as our addiction to go mobile has risen, so the new research is promising. Part of the problem is that technology cycles for components used in smartphones, tablets and laptops are increasing in speed. Hardware is getting faster and more capable while also shrinking in size. But the extra room gained inside devices is often used for more components and features, not bigger batteries that just make the devices heavier — not a desirable aspect.

Related research and analysis from GigaOM Pro:
Subscriber content. Sign up for a free trial.

• Sector RoadMap: Social customer service in 2013
• The next generation of battery technology
• Analyzing the wearable computing market