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CPRI Fronthaul Solutions

CPRI over CWDM Fronthaul to Cell Towers

This C-RAN application example illustrates how to transport four Common Public Radio Interface (CPRI) channels over one fiber fronthaul link using Coarse Wavelength Division Multiplexing (CWDM).

Omnitron’s iConverter CWDM/X MultiplexersCWDM/AD Add+Drop Multiplexers and xFF Transponders enable CWDM connectivity in a C-RAN over a fronthaul fiber link between Base Band Units (BBU) and Remote Radio Heads (RRH) located at two different cell towers.

The BBU is located at a BBU hotel or at a Central Office location. The fiber ports on line cards in the BBU support standard 1310 wavelengths.  Fiber patch cables connect the BBU line cards to iConverter xFF transponders installed in a high-density 19-Module Chassis.  The four xFF transponders convert the fiber with standard wavelengths to CWDM wavelengths (channels) with Small Form Pluggable (SFP) transceivers.  Standard wavelength SFPs and CWDM wavelength SFPs are installed in each of the xFF transponders.  The CWDM SFPs support specific wavelengths to enable connectivity to the matching channel ports on the iConverter CWDM/X multiplexer with fiber patch cables (shown in different colors to represent the CWDM wavelengths).  Omnitron’s CWDM transceivers have color-coded latch handles for easy identification. The CWDM/X multiplexes the wavelengths that transport the four CPRI channels over the CWDM Common Fiber Line (fronthaul).

CPRI Fronthaul

At the first cell tower, a 5-Module Chassis with a two-channel CWDM/AD Add+Drop Multiplexer and xFF Transponders is deployed. The CWDM/AD Add+Drop Multiplexer filters out the 1550nm and 1570nm CWDM channels to connect the CPRI data to the Remote Radio Heads in the cell tower. Fiber patch cables (shown in purple and green to represent the CWDM wavelengths) connect the channel ports on the iConverter CWDM/AD multiplexer to iConverter xFF Transponders that convert the fiber with CWDM wavelengths back to standard 1310 wavelengths. The standard wavelength fiber connects to the two Remote Radio Heads at the cell tower.

The 1510nm and 1530nm CWDM channels pass through the Add+Drop MUX and travel over the CWDM Common Line to the second cell tower.

At the second cell tower, another 5-Module Chassis with a two-channel CWDM/AD Add+Drop Multiplexer and xFF Transponders is deployed. The CWDM/AD Add+Drop Multiplexer filters out the 1510nm and 1530nm CWDM channels to connect the CPRI data to the Remote Radio Heads at the cell tower.

NOTES:

  • The two channels dropped off at each tower can be for different services. One channel can transport 3G, and the other channel can transport 4G/LTE to the tower.
  • Up to eight CWDM channels can be transported over a single-fiber CWDM fronthaul link (or sixteen channels over dual fiber) using iConverter CWDM/X multiplexers.
  • Remote Radio Heads support multiple fiber ports, enabling Wireless Carriers to connect multiple channels to each RRH at the tower.
  • For rural applications where coverage is more important than capacity, iConverter 2-Module Chassis can be deployed at each tower with a one-channel CWDM/AD add drop multiplexer and an xFF transponder to drop off one CPRI channel.

 

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