Samsung Galaxy S7, the first 4×4 MIMO smartphone

Samsung’s six month old flagship, the Galaxy S7 and S7 Edge, has just become a first of it’s kind LTE smartphone. T-Mobile users recently received the September Over-The-Air (OTA) update which appeared to be a routine security patch with some enhancements to Samsung Cloud backup, but it included a hidden gem. The OTA update also included a baseband firmware (G935TUVU4APIA) update which enables 4-Way Receive Diversity, as well as the ability to process four independent spatial streams, 4×4 MIMO. This milestone carries a significant weight in the world of mobile telephony and crowns the Samsung Galaxy S7 as the first commercially available 4×4 MIMO smartphone!

Device is powered by Qualcomm’s Snapdragon 820 processor with X12 integrated modem, the only solution on the market to support Higher Order MIMO/Modulation. The OTA update provides a unique opportunity for T-Mobile subscribers, given they get the privilege to experience the first 4×4 MIMO commercial LTE network in the real world. Note that an additional network enhancement, higher order modulation (Downlink 256 QAM, Uplink 64 QAM), hasn’t been enabled on the GS7/e with this OTA update. We intend to fully test the GS7/e in the coming weeks when another OTA should drop, but we wanted to share some preliminary findings with this initial OTA update.

We are delighted to continue our collaboration with Rohde & Schwarz (R&S), a global leader in test and measurement equipment. Rohde & Schwarz has provided the CMWflexx test equipment, TS7124 RF Shielded Box equipped with Vivaldi antennas ensuring high reproducibility of OTA MIMO measurements, and their invaluable engineering support. Cellular Insights takes full responsibility for the analysis, findings, and opinions in this report.

For this quick test, we have placed a Samsung Galaxy S7 Edge (S7e) into the R&S TS7124 RF Shielded Box, took our time to find the sweet spot inside the shielded box, and radiated a single 20MHz Band 4 LTE component carrier using R&S CMW500 Radio Communication Tester. As the device attaches to the eNb it reports its capability back to the network. The Galaxy S7 Edge with the latest OTA update reveals 4×4 MIMO capability on two unique Primary Component Carriers (PCC), LTE Band 4 and Band 2. It is also important to note that the X12 modem can process up to six spatial streams when leveraging 3-way carrier aggregation and 2×2 MIMO, but only four spatial streams (one component carrier) when attached to a 4×4 MIMO capable basestation. We observed this exact tradeoff in the field when attaching to live T-Mobile’s sites that once served our S7e unit with 3-way carrier aggregation before the latest OTA update. In situations where Band 4 isn’t the PCC (Band 12) Carrier Aggregation is still used, as all component carriers will use 2×2 MIMO. But improved signal robustness and improved data rates offered by 4×4 MIMO translate to a much better end user experience, while at the same time it allows operators to use spectrum more efficiently. Radiated OTA MIMO testing methodology gives us the entire view of the modem and antenna & front end performance on any commercial device.

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As portrayed in the above table, we observed peak data rates of 299Mbps starting at -80dBm. The throughput remaining unchanged until -96dBm where the 16 dBm decrease in power caused the speeds to drop ever so slightly to 296Mbps. At -98dBm data rates finally dropped to 274Mbps and then between -99dBm and -102dBm throughput stayed at approximately 257Mbps.

Between -110dBm and -114dBm, where most devices typically begin to struggle, the Galaxy S7 Edge managed to achieve over 100Mbps. This is where Qualcomm’s X12 modem really gets to shine, working in sync with RF360 Front End, closed loop antenna tuner, antenna switch diversity (ASDiv), and the new diversified antenna design. Even at -120dBm, where most devices would generally fail and lose a connection, we’ve observed 63Mbps on Galaxy S7 Edge. At -130dBm, 11Mbps was achieved using QPSK scheme, and the lowest TBSI. 

Designing a device with four highly efficient antennas in a small form factor is not an easy task. The main challenge is achieving high isolation between the antennas and low correlation of the received spatial streams, and with this preliminary test it is very apparent that Samsung has done a remarkable job. It becomes even more impressive if we remember that the Galaxy S7 and S7 Edge global launch happened in March, and over the past six months we haven’t seen a single 4×4 MIMO smartphone from any other OEM other than Sony (XZ Japanese variant). We will follow up with a full performance study on the Samsung Galaxy S7 Edge using multiple fading profiles, frequency bands, and 3-way carrier aggregation, but this preliminary test suggests that we potentially have the best performing LTE smartphone on the market.

Stay tuned: “Tale of a phone with two personalities…”