It's Getting Hot In Here, So....

It's Getting Hot In Here, So....

Our analysis of 5G mmWave thermal behavior with leading modems and smartphones

07/09/2023 | 21 pages

In this Signals Flash! we provide some results from a study that we did in collaboration with Rohde & Schwarz, which looks at the thermal characteristics associated with the baseband modems from some of today’s 5G smartphones. As always, unlike our subscription-based Signals Ahead reports, you may forward this Signals Flash! report to whomever you want.

More is Less. Although 5G mmWave phones tend to get hotter faster with more component carriers (CCs) and with higher MCS allocations, the subsequent higher data speeds more than offset the rate of increase in the temperature. Case in point, with one smartphone we tested, the temperature delta after downloading 1GB of data was 7.8x higher when downloading at ~72 Mbps (1CC and MCS 5) than at ~2,100 Mbps (8CC and MCS 16), even though the latter configuration increased the modem temperature 3.6x faster than the 72 Mbps scenario.

Results May Vary. Just like the diet plans advertised on TV, there are performance differences across smartphones. For the same MCS and number of component carriers, we documented up to a 2-3x difference across the phones in the rate the temperature increased. Further, there was up to an 18° C delta in the maximum temperature the smartphones reached before shutting down the 5G radio.

Differing Strategies.  Although we don’t specifically analyze this point in this report, we observed differences in how smartphones dealt with thermal issues. Some smartphones “go for broke” until the phone thermals, while other smartphones back off on 5G data throughput / number of concurrent component carriers when the temperature rises too much.