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remote radio head (RRH)

A Remote Radio Head (RRH), also known as a Remote Radio Unit (RRU), is essentially a compact, remote radio transceiver that is physically separated from the base station and is used in older 3G and 4G networks. Modern 5G networks utilize a newer functional split model where the RU (Radio Unit) is the closest thing to an RRU.


The RRH performs several key functions within a cellular network:


  1. RF Processing: It handles all RF functionality, including transmitting and receiving functions, filtering, and amplification[4].
  2. Signal Conversion: The RRH contains analog-to-digital (ADC) and digital-to-analog (DAC) converters, as well as up/down converters, to facilitate the conversion of radio signals to electrical signals and vice versa[1][4].
  3. Signal Transmission: In the transmitter section, the RRH converts digital signals to RF, amplifies them to the desired power level, and then the connected antenna radiates the RF signal into the air[5].
  4. Signal Reception: In the receiver section, the RRH receives the desired band of signal from the antenna, amplifies it, and converts the RF signal back to a digital signal in the receiver chain[5].
  5. Monitoring and Control: Advanced monitoring and control features allow operators to optimize performance from a remote, centralized location[4].


Components and Connectivity

  1. Base Band Unit (BBU): The RRH is connected to the BBU via fiber optic cable, which is preferred due to its lower loss and cost-effectiveness compared to RF coaxial cable[5].
  2. Antenna System: The RRH is usually mounted near the antenna to reduce transmission line losses[4].
  3. Common Public Radio Interface (CPRI): This standardized protocol is used for communication between the BBU and RRH[4].


Citations:

[1] https://en.wikipedia.org/wiki/Remote_radio_head

[2] https://www.telecomhall.net/t/what-is-the-different-types-of-rrh-and-their-functions/22593

[3] http://ieeexplore.ieee.org/document/6663274/

[4] https://www.everythingrf.com/community/what-is-a-remote-radio-head

[5] https://www.techplayon.com/rrh-remote-radio-head-connected-bbu-base-band-unit/

[6] https://www.researchgate.net/publication/353956272_Remote_Radio_Head_Scheduling_in_LTE-Advanced_Networks

[7] https://www.radiall.com/insights/what-is-rru-in-telecom

[8] https://www.rohm.com/solution/industry/infrastructure/base-station-remote-radio-head

[9] https://telecompedia.net/enodeb/

[10] https://www.cablefree.net/wirelesstechnology/4glte/remote-radio-head/

[11] https://www.linkedin.com/pulse/enodeb-same-bbu-samuel-olabisi

[12] https://www.cables-unlimited.com/glossary/remote-radio-head-rrh-or-remote-radio-unit-rru/

[13] http://www.eitc.org/research-opportunities/5g-and-beyond-mobile-wireless-technology/5g-and-beyond-technology-roadmap/the-fusion-of-fronthaul-and-backhaul/fronthaul/remote-radio-head-systems

[14] https://youtube.com/watch?v=n4X_FrXScrM

[15] https://www.sharetechnote.com/html/RF_Handbook_RRH.html

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