Mobile Data traffics are expected to increase annually by 25.2%1 between 2020 and 2027. With such an increase in data traffics, mobile operators cannot solely rely on conventional radios to carry that much traffics. To address the issue effectively, a powerful radio is required. It is called Massive Multi-Input Multi-Output (MIMO) radio. Massive MIMO has been playing a critical role in 4G and 5G networks for many years, and expected to increase its influence even more. Let us look at where Massive MIMO came from and where it is going.
Before Massive MIMO, there was MIMO. In 1993, two researchers proposed the use of spatial multiplexing, a wireless protocol to send multiple streams of data between transmitters and receivers to enhance throughput or functionality. This laid the foundation for MIMO. In 2010, industry experts start to write about Massive MIMO (though some of them originally called it ‘large-scale antennas systems’).
The word “Massive” in “Massive MIMO” does not refer to the physical size of the antenna, but to the number of elements. As the frequency is increased, there is a reduction in the spacing between the antenna elements, thus shrinking the size of the antenna.
Massive MIMO radio has many small antennas, which are used to serve multiple devices simultaneously. These tightly located antennas generate narrow beams which can be precisely focused. These tight beams strengthen the received power and reduce interference, increasing throughput significantly.
Here are some of the advances made in Massive MIMO:
Transmit and Receive
MIMO antennas are designated by the number of transmit and receive antennas used. 2T2R, for example, refers to a system with two antennas for transmitting and two antennas for receiving data, doubling capacity, or 4T4R, which refers to four of each, quadrupling capacity. 4T2R refers to four transmit antennas with only two receiving.
The most common Massive MIMO antenna sizes today are 32T32R and 64T64R. Although larger is generally better, larger can mean heavier and more demanding of power, so there are tradeoffs.
