CPRI / DAS RADIOS (DISTRIBUTED ANTENNA SYSTEM)

Distributed Antenna System Backhaul Applications


What Is DAS?
DAS (Distributed Antenna System) is a network of spatially separated antenna nodes connected to a common source via a transport medium that provides wireless service within a geographic area or structure. DAS is used by mobile telecom operators which seek to expand the capacity and reach of 4G networks around the world. DAS is a critical part of their network and typically uses a fiber optic backhaul, however, operators are now deploying high capacity 70/80 GHz E-band radios to augment their networks, especially where the cost of laying fiber lines is too high, too complex, or impossible due to physical/geographic issues or rights of way issues. 

What Is CPRI?
CPRI (Common Public Radio Interface) is an evolving protocol currently at version 6.0. It defines the interface of base stations between the radio equipment controllers (REC) in the standard, to local or remote radios. The CPRI specification has been developed and refined by companies including Ericsson, Huawei, NEC, Alcatel-Lucent, and Nokia Siemens Networks.

What Base Station Architectures Are Utilized Today?
There are five basic Base Station architectures utilized in today's networks.

1. Legacy architecture, with all of the equipment located inside the BTS hut, with a coax connection to the top of the tower and a fiber/copper connection to the Mobile Switching Center (MSC).
2. Split architecture design, with the BaseBand Unit (BBU) located indoors and a Remote Radio Unit (RRU) located on the tower. 
3. All-outdoor, zero-footprint BTS, with all components located on the tower (i.e., multiple boxes on a tower that travel via a combination of coax to the antennas and fiber/copper to the MSC without a BTS hut in between.
4. Capacity Transfer System (i.e., wireless BTS repeater concept).
5. “Base Station Hoteling” approach, which uses a single BTS hut but connects to multiple towers.

What is Base Station Hoteling?
Base Station Hoteling, in a Radio Access Network (RAN), is the concept of moving the base station into a local data center and connecting to the remote radio head on a tower or building using fiber or radios via the CPRI protocol. This architecture can increase network capacity while reducing the equipment necessary at the tower or building site.

Why is Base Station Hoteling Beneficial?
In the past, the most frequently used type of Wireless Base Station deployment (cell site/location) has consisted of a Base Transceiver Station (BTS) located close to an antenna tower and antennas. The BTS connnects to the Mobile Switching Center (MSC), which directs hand-off betweeen cell towers/radios for mobile users. The "Hut" at the base of a typical tower or in a building (basement/dedicated area) houses the RF tranceivers, RF amplifiers, baseband processing unit, test and alarm unit, AC power supply, battery backup equipment, and backhaul transport unit (MSC connection). This equipment is usually installed in one or more rack enclosures and usually requires climate control and backup systems (including large batteries), all of which takes up a substantial amount of square footage in a building. This architecture is also subject to high signal and power loss issues in the cables running between the equipment location and the tower/radios. Tower Mounted Amplifiers (TMA) are often required to boost the RF signal, adding additional costs.

Base Station Hoteling addresses many of these negatives. A remote "Hotel" (location) can be used to control multiple tower/antenna sites. This approach can dramatically reduce costs and speed deployment of 4G network base stations, espciallly in dense metropolitan areas where demand for bandwidth is growing exponentially.

Benefits of Hoteling/Distributed BTS Architecture:

  • One Hut can be located remotely from multiple antenna sites. This reduces equipment costs and facility costs. A Hut can be located in a "lower rent" building of choice.
  • Lower power requirements ("green solution").
  • Reduced perimeter security expenses around towers, and less vulnerability to vandalism/theft.
  • Less equipment at a rooftop site may reduce or eliminate need for reinforced rooftops/stability enhancements.
  • Easier/less expense servicing critical components.



LightPointe CPRI / DAS Backhaul Solutions:
Please contact LightPointe for more information about CPRI/DAS radio solutions, which offer extremely low latency and are capable of up to 1.2288 Gbps.

In addition to telecom / mobile carrier applications, LightPointe's backhaul solutions are ideal for Data Centers, HDTV transmission (e.g., HD-SDI / High Definition Serial Digital Interface / SMPTE 292M), and other applications.



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