Smartphone manufactures are advertising their new products by showing us high quality pictures, high performance processor and screen with beautiful colors. Sometimes they mention also about battery life time or resistance to damage and scratches. However, they never mention about Internet connection performance and features supported by mobile data modem.
This is very annoying, because you do not know if your new great smartphone will use the super fast LTE network of your carrier in 100%. How does it look nowadays? The LTE technology provides up to 150 Mbps downlink speed in 20 MHz cells when MIMO 2×2 transmission mode is used. MIMO 2×2 is supported by every LTE capable smartphone and cell tower. It means, that the base station uses two streams to transmit data to you and your smartphone uses two antennas in order to receive these streams. The same technology is used in home WiFi networks, where routers have two antennas.
Samsung Galaxy Note 7 will probably support MIMO 4×4 transmission mode for LTE cellular data.
In this mode, the cellular tower use 4 antennas to transmit 4 data streams and the smartphone uses also 4 antennas to receive these streams. The situation is the same as in case of WiFi networks. The MIMO 4×4 provides up to two times higher throughput than the MIMO 2×2 transmission mode. It means, that the mobile carrier is able to provide up to 300 Mbps downlink speed using a single 20 MHz cell. Nowadays, 300 Mbps transmission speed is also supported by e.g. Samsung Galaxy S7, but it requires using two 20 MHz cells with at the same time. This situation is very rare in the field, because you would have to have very good reception from two towers operating at different frequency bands.
Service menu of Galaxy Note 7 N930T has 4RxD Test mode option.
The photo has been taken in T-Mobile shop. As you can see, US version of Samsung Galaxy Note 7 is able to receive 4 data streams, but this feature is currently disable. It looks that Samsung has decided to use the full potential of Qualcomm X12 LTE modem. Therefore, the MIMO 4×4 mode in Galaxy Note 7 can be enabled by T-Mobile via OTA update. They have to only finish trial pilots of this functionality. However, this functionality was not confirmed by Samsung or any certification organization. It also was not confirmed if Samsung Galaxy Note 4 has 4 reception antennas, but I bet that someone will check this soon.