WiFi Performance

On most tablets, WiFi performance is perhaps one of the most crucial parts of the experience as WiFi is often the primary method of connectivity. Without working WiFi, a tablet is basically useless as the only alternative is either cellular (which is quite rare on most tablets) or Ethernet over USB-OTG, which destroys most of the value of a mobile device.

In the case of the Nexus 9, we see that HTC has fitted this device with a BCM4354 WiFi module to enable two spatial stream 802.11ac. Interestingly, there is some evidence to suggest that HTC has also adopted Cypress Semiconductor’s CapSense controller to enable antenna tuning for the WiFi antennas. However, it’s probable that this solution is only for HTC devices without a Qualcomm Gobi modem as we’ve seen the use of the QFE15xx antenna tuner in previous HTC products. In order to test how the Nexus 9’s WiFi solution performs, we turn to iperf on Android to test throughput across the network, and utilize Asus’ RT-AC68U router to ensure that the device under test will be able to reach maximum performance.

WiFi Performance - UDP

The Nexus 9's WiFi solution performs about as well as one might expect from a BCM4354 solution. For the most part I haven't noticed any reception issues, even when touching/detuning the WiFi antennas.

GNSS

While most of the GNSS solutions that we’ve looked at this year use Qualcomm’s GPSOne/IZat due to the presence of a Qualcomm Gobi Modem, the same isn’t true for the Nexus 9. Instead, Broadcom’s BCM4752 is used here. While this shouldn’t have a massive impact on the speed with which first lock is acquired, in practice Qualcomm’s solution is noticeably faster here as the modem can often provide data to make for a hot fix. At any rate, the Nexus 9 does perform acceptably in this regard. I don’t see any major issues with location performance, although it does seem that the GPS tends to report lower accuracy levels than the Qualcomm solutions that I'm used to. Other than this, the GNSS solution is quite usable.

Misc

While we don't have a proper audio quality test yet, it's clear that the audio codec used is the same Realtek RT5677 codec that we saw in the SHIELD Tablet. Outside of the code, we also see an RT5506 2.55V amp on the 3.5mm jack, along with two NXP TFA9895 amps on the speakers, which are quite good due to their front-facing placement. In practice I don't really see much issue with loudness or quality here, as the speakers can get even louder than the M8 in some situations. We also see a Broadcom BCM2079x NFC chip, which means HCE is fully supported out of the box. Interestingly, the VCM controller is exposed to the OS and is said to be a Texas Instruments DRV201 chip.

 

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  • AbRASiON - Thursday, February 5, 2015 - link

    LCD, not OLED? Blacks being grey? Nope :/
  • blzd - Friday, February 6, 2015 - link

    I'd actually rather grey blacks then the loss of detail in black areas. Pure black is nice, but not when it comes at the expense of shadow details.
  • techn0mage - Thursday, February 5, 2015 - link

    I agree that late is better than never. Rather than discuss things that can't be changed, I felt the following points were worth raising:

    Is there any Nexus 6 data in the benchmark charts? I didn't see any. The N6 and N9 were released roughly around the same point in time, and like the N5 and N7 they are high-profile devices in the Android landscape, so it would have been nice to have them in the charts to make comparisons. Please correct me if I've overlooked anything.

    The Denver deep dive, while certainly relevant to Nexus 9 and good AT content on any day, was probably a good candidate for having its own article. I believe it is fair to say the Denver content is -less- time sensitive than the overall review. Hopefully the review was not held back by the decision to include the "DDD" content - and to be clear right now I have no reason to believe it was.
  • WndlB - Thursday, February 5, 2015 - link

    Particularly in this kind of full-dress review of high-end devices, could you start covering the delivered sound, the DAC chips and headphone jack?

    Via A-B comparisons, I'm finding some real differences and, as people go to more high-quuality audiio streams (plus video sound), this is becoming a differentiator of significance. Thanks.
  • JoshHo - Tuesday, February 10, 2015 - link

    We could do subjective opinion, but properly testing 3.5mm output requires significant investment in test equipment.
  • name99 - Thursday, February 5, 2015 - link

    I know this isn't exactly a Nexus9 questions, but how can your battery life results for iPad Air2 be so inconsistent?
    We are given 10.18 hrs for "display a white image" and 13.63 hrs for "display video". For an OLED display this is possible, but not for a LED-backlit display unless you are running the video at a "base-level" brightness of much lower than the 200 nits of the "display a white image", and what's the point of that? Surely the relevance of the "display a white image" is to show how long the display+battery lasts under normal usage conditions, not when being used as a flashlight?

    My point is --- I am guessing that the "display a white image" test utilizes some app that prevents the screen from going black. Do you have confidence that that app (and in particular whatever tickling of the OS that is done to prevent sleep) is doing this in the energy optimal way, on both iOS and Android?
  • JoshHo - Tuesday, February 10, 2015 - link

    I don't believe there was any real background CPU usage. To my knowledge the difference is that Apple enables dynamic contrast in movies.
  • easp - Thursday, February 5, 2015 - link

    "The successor to the Nexus 7 was even more incredible, as it pushed hardware that was equal to or better than most tablets on the market at a lower price. However, as with most of these low cost Nexus devices not everything was perfect as corners still had to be cut in order to hit these low price points."

    So, hardware that was equal or better, except it wasn't? This is a situation where being more specific would help. My guess, when you said equal or better you were referring to certain specifications, certain obvious specifications like core count, RAM, and maybe screen resolution?
  • mkygod - Friday, February 6, 2015 - link

    Owned a Nexus 9 for almost 3 months. I purchased three actually to see if backlight bleed was any better, but nope; so I ended up returning them a couple weeks ago. The bleeding was pretty bad; worse than any LCD device i've ever used and definitely worse than the Nexus 5 and Nexus 7. And it would've been okay if it had uniform bleeding like the Nexus 5, but it had blotches of bright spots all along the edges which is even more distracting. I found the reflectivity with the screen a non-factor in my exclusively indoor use. It's a shame because the Nexus 9 is an otherwise damn good tablet. What's also disappointing, as the review points out, is if you want a high-end tablet around this size, your only options are the 9 and the Tab S. It seems like a lot of really good Android tablets are in the 8" size, such as the Shield and new Dell Venue, with more manufacturers on the horizon making tablets in this size.
  • MartinT - Friday, February 6, 2015 - link

    I wonder what level of load penalty is incurred by having to ship in optimized code from main memory. Is there any prefetching going on to preposition code segments in lower level caches ahead of being called?

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