WiFi Performance with Ixia IoT

As previously discussed, RF testing has always been a major unknown to some extent because environmental factors make it extremely difficult to tell exactly what is going on with the system. I don’t think it really needs to be said but previous reviews and any controversy regarding the quality of RF has always lead to a ring of confusion and back and forth with no clear-cut answers, at least in the public domain. The Transformer Prime and Pixel C reception issues have all been cases where I’ve seen a lot of confusion over whether a problem really existed in the hardware, software, or with the end user.

Most people really don’t have any understanding of how wireless transmission works, probably because it’s not really something you can see. As far as I know, no one is capable of seeing radio waves, even at high frequencies like 60 GHz. Of course, the problem is that for quite some time our testing was also not really ideal for seeing the quality of an RF implementation. While iPerf does provide some useful data, free space testing means that we’re dealing with channel conditions that inherently cannot be controlled. As a result, the only sensible test we could do with iPerf was focus on maximum throughput in the best conditions we could provide. The only thing that this can highlight is the upper bound of efficiency for WiFi due to the carrier sense multiple access scheme in most cases, and rarely detects a whole class of problems that affect user experience on WiFi.

In order to test these things we’ve moved to using a proper testing system that is actually used by at least a few OEMs today, namely Ixia IoT. While we discussed the possibilities for testing, at this time due to the RF isolation chamber used we are limited to AP simulation only, so we can’t properly simulate clients in the channel without restricting ourselves to a single spatial stream for both the AP and client. This wouldn’t be a very useful test if set up in this manner as most devices today that we’re testing have support for two spatial streams, and many routers have three or even four spatial streams at this point.

The first set of results we can talk about that will be of interest is rate vs range. This is a fairly simple test at a conceptual level, as it simply tries to see how well a device can maintain its performance in the face of reducing signal to noise ratio for a given modulation and coding scheme. This is a good high level test of how well a device can maintain a connection as reception degrades. In this test the HTC 10 had an initial RSSI of -28 dBm while the GS7 was at -21 dBm and the iPhone 6s at -22 dBm, which allows us to calculate the path loss and determine the RSSI as a function of the transmit power.

The results of this test are interesting to say the least. Off the bat, every device had different RSSIs measured, so this meant that everything had different levels of path loss. The HTC 10 seemed to have the most path loss, while the Galaxy S7 and iPhone 6s were functionally identical. However it looks like RSSI is really an insufficient metric here because while the iPhone 6s was able to reach maximum throughput using NSS 2 MCS 8, the HTC 10 and Galaxy S7 did its best at NSS 2 MCS 4 or 5. I suspect this may be just due to placement as device positioning strongly affects MIMO as receive-side spatial correlation reduces the gains that MIMO can provide. Regardless, the HTC 10 somehow manages to beat the Galaxy S7 through much of the curve, but for some reason suffers from a reduction in throughput at higher transmit power. It's worth mentioning though that this test doesn't allow for testing of antenna gain or similar tests. Given various levels of futzing about with the device positioning in the test chamber I'm fairly confident that the Galaxy S7 is consistently better with regard to path loss, so even if it doesn't perform as well at a given RSSI it tends to have a higher RSSI than the HTC 10 by about 5 dBm which is fairly significant. I'm hoping to get some true antenna efficiency measurements with 3D plots in the near future so we can really give some real data on everything relevant here but for now this test highlights fairly well how WiFi performance varies.

Finally, the other test that we can run at this time is the roaming latency test, which tests how well a device can hop from one access point to another as the received transmit power rises and falls. If you ever rely on WiFi to work as you walk around any building larger than a single apartment unit, you’re going to feel the effects of high roaming latency as VOIP calls or any real-time network application will either experience interruption or drop altogether if roaming is not implemented properly.

WiFi Roam Latency

Like the Galaxy S7, the HTC 10 really struggles with WiFi roaming as it seems almost universal that Android OEMs aren't really paying attention to anything that we don't test. The HTC 10 tended to not fail handover as often as the Galaxy S7 with only one failure out of 64 trials and fairly consistent latency around 110ms though. This is a bit of a surprise considering that the HTC 10 is generally considered in the broader discourse to have worse WiFi across the board compared to the Galaxy S7. Considering how much smaller HTC is this is really kind of strange to see. Just about anything will outperform the Pixel C though. Either way, HTC still should improve here, especially when considering how most schools and offices need good WiFi to make up for areas with cellular coverage gaps.

Software UX: HTC Sense Latency with Google WALT and Misc.
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  • MobiusPizza - Tuesday, September 20, 2016 - link

    These results are probably not a surprise if you’ve been following our recent coverage but it’s still worth noting how the use of eMMC 5.1 is not guaranteed to be a huge impediment, although I would say this is probably the last generation where it’s acceptable to ship eMMC in a flagship device as the eMMC spec doesn’t seem to be progressing much further and UFS/NVMe solutions really seem to be the way forward as far as the industry is concerned.


    Gosh that sentence is quite a mouthful
  • asfletch - Tuesday, September 20, 2016 - link

    Agreed. Also re the content - is it surprising to anyone else that UFS solutions don't have a clearer advantage over eMMC? I mean my 2014 Note 4 gets about 19/7 on Random Read/Write with the same Androbench settings. According to these charts, that's better than the current Note 7. Also the HTC 10 here on test beats all of the UFS phones handily for Sequential Write speed.

    What's up with that? Is it the benchmark?
  • Guitahero - Tuesday, September 20, 2016 - link

    What happened with the deep audio analysis from anandtech?
  • JKJK - Tuesday, September 20, 2016 - link

    Indeed! I miss them too!
  • winjay - Tuesday, September 20, 2016 - link

    "for its size I don’t believe there’s another Snapdragon 820 device with better battery life."

    Sony usually does wonders with battery life. Have you checked Xperia XA battery life?
  • Vagabondjonez - Tuesday, September 20, 2016 - link

    with a 2k display he probably meant
  • winjay - Tuesday, September 20, 2016 - link

    Also this phone is said to have an amazing DAC. How is the audio output?
  • Ro_Ja - Tuesday, September 20, 2016 - link

    The front looks like a Samsung Galaxy.
  • amosbatto - Wednesday, September 21, 2016 - link

    This review (and every other review I have ever read) doesn't cover the most important issue, which is the longevity of the phone. Here are the issues which I suggest that a review should cover:

    1. We all know that the battery will die after 2 years. Every phone which has a replaceable battery should automatically get a higher rating, just because it will probably last longer than one which doesn't. If a phone has a sealed case, the reviewer should try to open the case and give readers an idea how hard it will be to replace the battery. If the case is glued together, if the battery is glued to the case or if it is impossible to buy replacement batteries on the internet, then the review should let us know.

    2. Reviews should emphasize the amount of storage space a phone has and how expandable the phone is, because this has a big impact on how long the phone will last. If a phone is limited to 32 gigabytes of storage, then the phone will probably not last more than 2 years, because people tend to buy new phones once they run out of space. Trying to decide what apps to uninstall, what music to remove, what photos to delete, etc. is such a painful process, that many people simply buy a new phone. Reviews should really knock phones which don't have a MicroSD slot to expand storage and I would love to see some benchmarking on the difference in speed between the internal NAND and a normal MicroSD.

    Frankly, I wish that smartphone manufacturers would offer us phones with two MicroSD slots, where one is used to expand the storage for apps on the phone and the second is the memory that we can remove to transfer files to our PC.

    Another thing that reviews should cover is how hard is it insert and extract a MicroSD card. On my HTC Sensation from 2011, it was very easy to pop the MicroSD card in and out of the computer, but it can't be done without a special tool on my Moto X Pure Edition. Not a single review ever covers how hard it is to insert and extract the MicroSD card, but this is essential information for people like me who intend to keep their phones for many years.

    3. Every review should mention how good the manufacturer is about offering security updates and OS upgrades to its phones, which are essential for extending the life of the phone. HTC has an excellent track record of offering fast updates when a new version of Android is released, whereas Samsung does not. Every review comparing an HTC phone to a Samsung phone should mention this difference, because it will influence the buying decisions of people who care about the longevity of their phones.

    4. Another way to extend the life of a phone is to install an OS that doesn't come from the manufacturer. If the manufacturer stops offering upgrades, then we have the freedom to install CyanogenMod or another mod to get the new features in the latest version of Android. No review ever covers how hard it is to unlock the bootloader and install a mod in the phone, but this is essential information for a phone buyer who wants to be able to keep upgrading the phone. Does the manufacturer offer for free the code to unlock the bootloader and does it have a policy of voiding the warranty if a mod is installed? Five years ago when I bought my Sensation, HTC had the best mod policies in the industry, but I have no idea who is best today and this review didn't mention it.

    Another piece of essential information is how standard the hardware is and how likely mods will be developed for the phone. For example, the SoC on the HTC 10 is a standard Qualcomm Snapdragon 820, so it is highly likely that mods will be made for this phone, whereas it is highly unlikely that mods will ever be created for a custom SoC made by Huawei, Samsung or Apple. Yes, that custom SoC probably processes a couple milliseconds faster, but frankly most people will never notice the difference.

    5. Another way to extend the life of a phone is to turn it into a PC. I frankly don't see the point of buying a flagship phone like the HTC 10 which costs $600, but I might consider it if I know that it can be used as a low cost PC. Kudos to this review for at least mentioning that the HTC 10 supports Slimline and Android 7, but it doesn't explain why that is important. The phone has the necessary hardware and software to be hooked up to a monitor and bluetooth keyboard and mouse, so it can be used as a PC with multiple windows and a mouse pointer. I would have loved to read a review about how well this works with the HTC 10.

    Reviewers spend an inordinate amount of time covering differences in processing speed and other minutiae which most people will never notice when using a phone, but they don't provide the most essential information to help people choose phones with long lifespans. Part of the reason is that reviewers are the type of people who get a new phone every year, so they don't worry about the battery wearing out. However, I think a more important factor is that fact that sites like AnandTech rely on advertising from the same manufacturers who they are reviewing. Manufacturers of smartphones and other electronic devices promote planned obsolescence as a way to increase their sales. A reviewer who dwells too much on the fact that a phone is designed to be thrown away after two years probably won't get much advertising and is unlikely to get free samples to review.

    Apple has always had some of the worst policies in the industry in terms of planned obsolescence, but within the last 5 years the entire phone industry has started to copy Apple in designing sealed black boxes which are difficult to open and even harder to fix. Yet, I have not seen a single review of the iPhone 7 or any of the other recent smartphones which even mentions how hard it is to fix the phone or even replace the battery. If the reviewers don't mention it, then consumers won't think to check and the phone industry will conclude that consumers don't want fixable and modifiable phones, so they will offer more and more Apple-like devices.

    Extending the life of smartphones is not just a way to save consumers money. One of the biggest ecological problems on the planet is the fact that 1.5 billion smartphones will be manufactured this year and most of them will be junked within 2 years. More smartphones are manufactured today than all the other ICT devices combined (servers, routers, desktop and notebook PCs, tablets, gaming consoles, cameras, televisions and advanced wearables). The amount of energy, metals and other vital resources which are wasted every year in making throwaway devices is astounding. If we estimate that the average smartphone and its charger weighs 150 grams, that means we are generating 225,000 metric tons of eventual e-waste every year, which is toxic and needs special treatment.

    Even more alarming is the amount of greenhouse gas emissions being generated to manufacture all these smartphones. Apple estimates that 83.6 kg of CO2-equivalent were emitted to manufacture and transport its iPhone 6 to point of sale, whereas using an iPhone for a year emits 3.5 kg CO2-e and recycling it at the end of its life emits 1.0 kg CO2-e. Of course, Apple didn't include all the energy to operate the cell towers, internet servers and routers, etc. that are used by an iPhone, but manufacturing a smartphone clearly has far more environmental impact than using it, so the best way to lower the environmental impact is to make the phone last as long as possible in order to avoid manufacturing a new phone.

    Apple does not explain how it calculates its emissions, but it is highly likely that Apple did not include the SF6 which was emitted in manufacturing its screens or all the other types of greenhouse gases which often get overlooked. It also probably doesn't include in its emissions all the advanced processing to make the ultrapure chemicals, water and gases which are used in silicon and flat screen fabs. Today's crop of smartphones probably have an even higher environmental impact, considering that they are using larger screens, more memory and more processing cores than the iPhone 6, which had a 4.7in screen, 1 GB of RAM and 2 processing cores. Now-a-days, 5-6in screens, 2-4GB of RAM and 4-8 processing cores are the norm, so we can conservatively estimate that manufacturing today's smartphone will emit 100 kg CO2-e. For the 1.5 billion smartphones produced in 2016, that means 150,000 metric tons of CO2-e.
  • Allan_Hundeboll - Wednesday, September 21, 2016 - link

    You def. have a point

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