Apple's iPhone 7 and iPhone 7 Plus come with one of two cellular modems, Qualcomm's MDM9645M modem or Intel's XMM7360 modem, depending upon the associated mobile carrier.
In ideal conditions, the two modems perform equally well. But research firm Cellular Insights claims that at the edge of cell coverage areas, where signal strength falls off, the iPhone 7 model with the Intel modem is less capable.
The iPhone 7 (A1660) and iPhone 7 Plus (A1661) sport the Qualcomm modem. Variant models, the iPhone 7 (A1778) and iPhone 7 Plus (A1784), come with the Intel modem. For US customers, Sprint and Verizon offer the Qualcomm-powered iPhone. AT&T and T‑Mobile US sell the Intel-equipped version, which won't work on the CDMA networks operated by Sprint or Verizon.
The Qualcomm modem supports a wider set of protocols, making it usable on any of the big four carrier networks in the US. So unlocked iPhone 7 models purchased for Sprint or Verizon in the US can be used with the networks operated by AT&T or T‑Mobile US. Apple provides information about where its various iPhone 7 models are available on its website.
Cellular Insights tested the LTE performance of the two modems across three bands, Band 12 (10MHz), Band 4 (20MHz), and Band 7 (20MHz) in 4×2 MIMO configuration using Transmission Mode 4.
According to the firm's report, iPhone 7 models with the Intel modem exhibited 30 per cent worse LTE performance on average than their Qualcomm-equipped counterparts when conditions were not ideal.
With a strong wireless signal, the two variants kept pace. But at lower signal strengths, differences start to emerge. At -95dBM, the Intel modem required an adjustment of its Transport Block Size because the Block Error Rate exceeded 2 per cent. With a signal measured at -105dBm, the Block Error Rate reached 20 per cent. And at -108dBm, it went to "a whopping 75 per cent."
High error rates mean low LTE performance.
"In all tests, the iPhone 7 Plus with the Qualcomm modem had a significant performance edge over the iPhone 7 Plus with the Intel modem," the report concludes.
Apple's dual sourcing strategy reflects a desire to avoid having to waste space or money by having a large, expensive component so jammed with circuits that it will work with any telecom infrastructure, according to Fast Company. It also provides a defense against dependence on a single component supplier and price negotiation leverage.
But the cost of this strategy if electronic components exhibit such varied performance may be customer satisfaction.
Neither Apple nor Intel responded to requests for comment. ®