【MIMO 从入门到精通】[P9]【What is beamforming in 5G NR】

前言：

   本篇主要转载

  【Optimization Hassle - Q & A [Interviews]】 What is beamforming in 5G NR

      Beamforming 仿真工具数学原理:

      Welcome to Arraytool’s Documentation! — Arraytool v0.0.0 documentation

https://github.com/zinka/arraytool

https://en.wikipedia.org/wiki/Phased_array

https://en.wikipedia.org/wiki/Radiation_pattern

目录：

1.  what is beamforming in 5G
2.  what  is factors that effect beamforming performance
3.  SRS & UCI 
4. what is 3D or FD beamforming
5. what are types of beamforming?
6. what is transmission mode(TM) in beamforming?

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一   what is beamforming in 5G

A radar antenna focuses transmitted energy in a narrow（狭窄）, conical-shaped beam（圆锥形的波束） (see Figure 1). The angular width of the radar beam is defined as that region of transmitted energy that is bounded by one-half (-3 dB) the maximum power. Around 80% of the energy is contained within the main beam（主波束）, with the sidelobes(旁瓣） generally being more than 1000 times less intense in a high quality antenna (unlike in the p-theta graph)

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 二  what  is factors that effect beamforming performance

 

N  = number of elements

Ge = element gain

Gt = antenna gain

Pt = total transmitter power

Pe = Power of per element

Tn = noise temperature

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三  SRS & UCI 

NR上行物理信号包括探测参考信号（Sounding Reference Signal，SRS）

上行控制信息（Uplink Control information，UCI）,用于向基站报告UE的状态，如HARQ接收的状态、信道状态信息等。

 

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四  what is 3D or FD beamforming

Answer:

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3D beamforming refers to use of mMIMO for steering beams both in the horizontal

(Azimuth 方位角) dimention and vertical垂直(elevation 高度) dimentions

if we  have a contol in beams in both vertical & horizental domain，

so we have 3D or  Full-mMiMo beamforming

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五   what are types of beamforming?

    Answer:

    ----------------------------------------------------------

     Beamforming types are 3 and they are:

     1  Digital beamforming:

        each antenna branch have seperate TRX  .

     so  if for example, we have 32 Antenna-element, so we have to implement 32TRX

    --can transmit  multiple antenna pattern (beams) simulanously

     --used for low frequency band as limited antenna element is required as TRX needed

per antenna branch

   - high power comsumption and high cost

2  Analog beamforming:

  - all antenna branch have only single TRX so if for ex,we have 32 antenna-element
  so we have to implement only one TRX
  - can transmit only one antenna patterns(beams) at a time in specific direction
  -used for high frequency band as no limitation in number of TRX(only one) as in digital 
  beamforming.
  -low power consumption and low cost

3  Hybrid beamforming:

  -combines the digital beamforming and analog beamforming
  - the number of TRXs and RF Chains in the beamforming antenna are in 
  general lower than the number of antennas
  
  - The motivation for hybrid beamforming is to minimize the number of RF chains,
  which will reduce  energy consumption and design complexity , making it more general
  cost-effective

 

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 六  what is transmission mode(TM) in beamforming?

      Answer:

      --------

      when enabling beamforming in mMIMO ,we have switch to three types of transmission

mode TM and there are:

        TM7:

         Use  single-stream beamforming(one code-word) Rank as diversity mode without spatial

multiplexing

           use antenna port number-S

    TM8:

          Use dual-stream  beamforming(two-code-wod)rankd2 as spatial-multiplexing MIMO.

use antenna port 7&8

    TM9:

      use 8 streams beamforming  as 8T8R MIMO.

use antenna port 7,8,9,10,11,12,13,14

 

 Beamforming