8T8R vs 64T64R | Difference between 8T8R and 64T64R Massive MIMO antenna

This page compares conventional 8T8R antenna vs 64T64R massive MIMO antenna and mentions difference between 8T8R and 64T64R Massive MIMO antenna types.

What is Massive MIMO ?

Massive MIMO refers to system having multiple antenna elements in the form of active antenna array used to transmit multiple data streams in the desired direction. It helps to increase system capacity, data throughput and coverage.

Massive MIMO is also called as mMIMO. It employs beamforming to direct energy in the desired user direction to mitigate interference from other users.

There are two types (SU-MIMO and MU-MIMO) based on number of users served by Base Station or eNB. In SU-MIMO, all the streams of antenna array are focused on single user. In MU-MIMO, multiple streams are focused on multi users. Each of these streams of MU-MIMO antenna system provide radiated energy to more than one users simultaneously. Massive MIMO uses MU-MIMO in which multiple radio transceiver units are combined with anetnna elements on single active unit.

Conventional 8T8R Antenna

• Each column uses 8 antenna elements to create vertically fixed direction pattern.
• The eight columns, each used with a single transceiver for signal transmission, are designed for horizontal beamforming only.
• 8T8R refers to 8 transmit and 8 receive antenna elements i.e. 16 total antenna elements.

64T64R Massive MIMO Antenna

• 64T64R refers to 64 Transmit and 64 receive antenna elements i.e. 128 total antenna elements. (Row x Column x polarization equals 8 x 8 x 2).
• Maximum number of layers (Lm) supported are 16.
• It has 64 RF Transceiver units, each mapped to two antenna elements. Both uses different polarizations to transmit different unique data streams. Both the polarizations are at 90 degree to each other referred as cross polarization.
• All 128 antenna elements create antenna pattern, with array design enabling both vertical and horizontal beamforming.
• The addition of vertical dimension, with per antenna element adjustments, turns a column of antennas into antenna array allowing many more layers and much finer adjustments.
• Both FDD and TDD are used with massive MIMO. TDD operates on same frequency on downlink (DL) and uplink (UL). FDD operates on different frequencies for DL and UL. TDD is better than FDD due to channel reciprocity. With FDD, feedback overhead increases with antenna elements.