Apple has a reputation for tight supply chain management and demanding rigorous quality control, but the company may have a modem problem on its hands. Previously, Apple has tapped both Samsung and TSMC to build its SoCs, but stuck with the same Qualcomm modem for all its hardware. With the iPhone 7, Apple adopted an Intel modem for its AT&T and T-Mobile variants, while the factory-unlocked devices, Sprint, and Verizon hardware all use Qualcomm’s modem silicon (MDM9645M if you want to get technical).
According to an analysis performed by Cellular Insights, both devices perform equally well if you have a strong signal, but the Intel modem (XMM7360, pictured at top) drops off significantly as signal strength weakens. Cellular Insights tested multiple LTE bands (Band 4, 7, and 12) in a 4×2 MIMO configuration. The graph below is from Band 4, which Cellular Insights describes as the most common band for North America LTE deployments.
RSRP is a measure of LTE signal strength and is expected to range from ~-75dBm when measured directly on top of a cellular base site to -120dBm at the edge of coverage. What we see here is that the Intel modem can’t sustain the same throughput as the Qualcomm device, particularly at the -105dBm threshold. At -115dBm, the gap between the Intel and Qualcomm modems is roughly 2x — meaning the Qualcomm device is sustaining about twice the network throughput on the same signal strength.
Cellular Insights also compared the two devices against the Galaxy S7 Edge, the iPhone 6s, the LG G5, and the Nexus 5X.
First of all, kudos to Samsung; the S7 Edge does extremely well in all cases. The Intel XMM7360, in contrast, is the worst overall performer of the lot — though the 6s doesn’t exactly distinguish itself well, either. That might explain why Apple was willing to work with Intel in the first place, but the Intel XMM7360 doesn’t keep up with Qualcomm’s MDM9645M.
It would be interesting to see a battery life comparison between Intel and Qualcomm devices and it’s possible that Apple could improve the Intel modem’s performance via a software update. If you really care about LTE performance on an iPhone or live in an area with marginal LTE coverage, the factory-unlocked version of the device is definitely your best bet — right now, the Intel modem isn’t performing where it ought to be.
Winning the iPhone 7 was a huge victory for Intel’s beleaguered modem division, but that victory was predicated on the idea that the Intel and Qualcomm modems would offer equal performance. So far, that doesn’t seem to be the case. It’s not clear how much this impacts the iPhone 7’s range, network timeouts, or other issues that might arise in areas where cellular connectivity is weak, but the general implication is that the Qualcomm modem offers better performance and possibly better range when operating in low-signal areas.