Remote Radio Head in 5G NR | 5G RRH manufacturers
This page describes 5G remote radio head (5G RRH) basics and functions of its internal modules. It mentions vendors or manufacturers of 5G RRH (Remote Radio Head) units.
Remote Radio Head (RRH) architecture consists of baseband unit (BBU) and remote radio unit(RRU). Both BBU and RRU are connected using fiber optic cables to transport digital data and control information. Initially Common Public Radio Interface (CPRI) has been developed as interface protocol in RRH deployment especially in 4G LTE and 5G networks. The CPRI interface carries digital baseband signals including data, control and synchronization information over optic fiber cables at high data rates. Later enhanced CPRI (eCPRI) has been developed to meet low latency and high data rate requirements of 5G NR (New Radio) signals.
What is 5G RRH ?
In 5G New Radio network, Remote Radio Head (RRH) plats vital role in providing wireless coverage and capacity.
RRH specifications vary as per equipment manufacturer, deployment scenario and telecom network operator.
In general, common specifications or features of 5G RRH are as follows.
• Frequency bands and Bandwidth including sub-6 GHz and mmwave frequencies.
• RRH should support multiple antennas to enable MIMO transmission and reception.
• RRH should support digital beamforming.
• RRH should be capable of operating in TDD and FDD modes as per specific deployment scenario.
• RRH should support eCPRI interface between baseband and radio units.
• RRH should be capable of transmitting required power to ensure adequate coverage.
• RRH should be designed to minimize processing and transmission delays so that required latency can be achieved.
• RRH can be monitored and controlled remotely.
• RRH should be energy efficient to maintain overall network performance.
• RRH should be compact in size and should withstand all environment conditions during outdoor usage.
• RRH should work with 48V DC power supply.
The figure-1 depicts typical cellular base station using RRH technology. As shown radio units (i.e. RE) are installed close to the RF antennas and BBU (Baseband Units) are installed at some distance from radio part. Both radio front end (RFE) and BBU are connected using fiber optic cables.
5G Remote Radio Head modules
REC part of RRH consists of ADC/DAC, RF up/down converter, Power Amplifier (PA), Low Noise Amplifier (LNA) and RF duplexer/switch. RE part consists of PHY layer modules as defined in eCPRI and 5G NR specifications. Let us understand functions of these modules. PA, LNA and RF duplexer/switch are together known as RF Front end. Both BBU and Radio end part are connected via fiber optic cables. The information fields (data, sync, control & management) are transmitted using CPRI/eCPRI format.
As shown in the block diagram of RRH (Remote Radio Head), transmit chain performs following functions.
• Information to be transmitted is passed through Physical layer modules such as
LDPC encoding, scrambling, modulation etc. Refer eCPRI and 3GPP specifications for layer-1 blocks of 5G NR.
• The modulated baseband signal is converted to optical form as per eCPRI format and transmitted using fiber optic cables.
• The optical signal is converted back to electrical form at the radio end (RE part) of RRH.
• The digital signal is converted to analog form using DAC (Digital to Analog Converter).
• The analog signal is up converted to RF (Radio Frequency) level using RF mixer and LO (Local Oscillator).
• The up converted RF signal is amplified to desired power level using PA (Power Amplifier).
• The amplified RF signal is transmitted into the air using antenna or antenna array as per requirements.
The receiver chain performs reverse functions of that performed by transmit chain. It passes RF signal through LNA (Low Noise Amplifier), RF down converter (using mixer and LO) and ADC (Analog to Digital Converter). The analog electrical signal is converted to optical form and transmitted via fiber optic cables to BBU (Baseband Unit). At baseband unit, physical layer blocks (demodulation, descrambling, LDPC decoding etc.) get back the information.
RF duplexer or switch is used to share the same antenna between transmit and receive portions. For FDD topology, RF duplexer is used to separate transmit and receive frequency bands. For TDD topology, RF switch is used for separation of transmit and receive time slots.
5G RRH Manufacturers or Vendors
Following table mentions 5G RRH manufacturers or vendors.
| 5G Remote Radio Head Manufacturers | Description with features |
|---|---|
| Ericsson | AIR 6488 unit is an antenna integrated radio unit. It supports 64Tx/64Rx Time Division Duplex (TDD) Advanced Antenna System (AAS) for 5G NR network deployment. It supports eCPRI interface between baseband and itself (AIR). Optical cables are used for traffic and timing signals between AIR radio unit and baseband unit. Visit ericsson.com for more products. |
| Nokia | Airscale system module supports 2G, 3G, 4G and 5G deployments. The company has many solutions which include AirScale baseband, Airscale massive MIMO radios, Airscale mmWave radios and so on. Visit nokia.com for more solutions on 5G NR and other standards. |
| Samsung | Company develops baseband module which supports both LTE and 5G network features. Company offers many products including Massive MIMO radio from single band to multi band with various antenna configurations such as 64T64R and 32T32R. Visit samsung.com for more products and solutions for 4G, 5G and 6G etc. |
| Huewei | The company develops solutions for various cellular technologies including 2G, 3G, 4G and 5G NR. The company offers multi-band RRU (Remote Radio Unit), BBU (Baseband Unit), RF antennas and 5G AAU (Active Antenna Unit). One such product is RRU5818 which supports 2T, 4T, 8T MIMO configurations and different frequency bands. Multiple RRUs can be interfaced with single BBU 5900. Visit huawei.com for more information on other products and solutions. |
| WIRELESS EXCELLENCE LIMITED UK | The company offers Remote Radio Head (RRH) for CPRI and 4G LTE and 5G networks. Visit cablefree.net for more products and solutions. |
Remote Radio Head (RRH) Related Links
• Article on RRH basics and its interfaces
• Benefits and limitations of RRH