As part of Sprints Next Generation Network (NGN) upgrades, Sprint has been actively deploying antenna setups that have a total of 4 individual 800 MHz antenna ports.
It was first discovered with the 16 port triband antennas which had four 800 MHz ports, four 1900 MHz ports, and eight 2.5 GHz ports. Subsequently, 10 port dual band 800 MHz and 2.5 GHz antennas also began to appear shortly after in deployments alongside Network Vision era 6 port 800/1900 MHz antennas bringing the total amount of 800 MHz ports in use to four per sector.
And for what reason one might ask?
It's for 2 Transmit and 4 Receive (2Tx4Rx) diversity for 800 MHz at the cell site.
Deploying such an antenna setup enables the eNB to maintain a stronger connection to UE which results in improved LTE data speeds and coverage as the device uplink is almost always the first to fail. This serves as a huge plus in terms of supporting Voice of LTE (VoLTE) as ubiquitous LTE coverage is essential for Sprint as there is no legacy voice fallback.
With the these new 8 port dual band antennas, Sprint can now provide more consistent 800 MHz service than two individual antennas provided in the 10 port dual band antenna configuration provided and removed the extraneous 2.5 GHz hardware from the 16 port triband antenna where it is no longer needed. These new antennas will now stand alone next to 2.5 GHz Massive-MIMO antennas or older 2.5 GHz RRH and antenna configurations. Both highly optimized in what they do best.
Nokia - Alcatel-Lucent
2x50w 800 MHz RRH + 1.9 GHz 4x45 RRH + 2.5 GHz 8x20 RRH
800 MHz RRH-C4 + 1.9 GHz RRH-P4 + 2.5 GHz 8x20 RRH-V3/B8