Remote Radio Unit | RRU
Radio Remote Unit(RRU) is the distributed and
integrated frequency unit that connects to an operators network with the
User Equipment's (UE's) like Cell Phone and mobile devices.
The logical term "distributed and integrated" is
because traditionally the radio architecture for cellular system is
based on a single-standalone system(Base Stations) usually installed
indoor but now, the cellular architecture is divided.
So now the BTS(Base Transceiver Station) is the integration of
various radio unit like BBU and RRU. Despite installing only in indoor ,
radio units are now installed in the tower below the Antenna.
The RRU is connected to the base station via the fiber optic link
which is bi-directional link. The optical interface link is also known
as CPRI(Common Public Radio Interface). CPRI is a interface protocol
developed by combination of major telecom equipment's manufacturing
company.
The RRU helps to reduce the coaxial feed line losses, increase
system efficiency and provide high level of flexibility in cellular site
construction. Undoubtedly, this helps in upgrading to new equipment's
and devices more easily.
RRU Functions:
1) Acts as a transceiver: transmit and receive the user signals to the base station and vice-versa.
2) Provides back to back support and connectivity between user equipment's like power, delay,etc.
3) Control and process the EM signals received from the Antenna via Jumper(Hollow Guide).
4) Provide interface between two physical link: Optical and EM(Electromagnetic).
5) Provide Controlling support of the Auxiliary
equipment's like RCU (Remote Control Unit) for electrical tilt
adjustment generally known as RET(Remote Electrical Tilt).
6) Generate and sends the different signals like VSWR, RET, ACT,etc.
RRU Hardware Description:
1) CPRI Port: There is 2 port generally named as
CPRI0 and CPRI1. However there may be 1's in some model. The name at
suffix may vary. Its function is to connect to BBU.
2) RF Port: We say it as a Jumper port. The number
of jumper port may vary with model and company's architecture. At least
there is 2 jumper port, one of which is for Tx and another for Tx/Rx.
The RF port is connected to the Antenna via Jumper Cable.
3) RET Port: There is at least one RET port for
connection to RCU. The connector is mostly DB9 in Huawei and may vary
with other company's. RCU is connected to the Antenna. RET cable
connects the RCU and RRU.
4) Power Supply Port: There is one port for
powering the RRU. Mostly blue and black. Blue is for negative (-) and
black is for zero(0). Generally all RRU operates in -48V.
5) Ground Port: There is two OT port for the
grounding. The ground cable: mostly copper wire, one end is connected to
RRU and another end into Bus Bar near by RRU. Thus it provides the
surge and high voltage protection of RRU and thus keeping safe from
natural weather and climates.
Finally be informed that there are
RRU for band 900
RRU for band 1800
RRU for band 2100
and depending on planning you could operate any bant to work in dual band
If you want PDF for Huawei RRUs i will send it to u
BR
