CHAPTER 1: ERICSSON W-CDMA
BBU/RRU SYSTEM
Overview of RBS3402/3418/3518 BBU/RRU Product Offering
Like all other wireless base station equipment OEMs, Ericsson offers a baseband unit
(BBU)/remote radio unit (RRU) BTS architecture in additional to traditional macrocell
BTS cabinets.
The Main Unit (MU) BBU is a 4U height 19” rack mounted system that is capable of
supporting up to six RRUs (in a 6x1 configuration). A standard configuration would
be three RRUs and a Main Unit. Currently, Ericsson manufactures four different
frequency versions of its W-CDMA RRU product:
850MHz (Band V)
1900MHz (Band II)
2100/1700MHz (Band IV)
2100MHz (Band I)
Exhibit 1: Ericsson RBS3000 W-CDMA NodeB System
Source: Ericsson, EJL Wireless Research LLC (November 2010)
Exhibit 2: Ericsson RRU 22IV40 System Block Diagram
Source: EJL Wireless Research LLC (November 2010)
Exhibit 3: RRU Protection Circuit PCB Component Diagram, Top View
Source: EJL Wireless Research LLC (November 2010)
The protection circuit for the RRU uses a single sided PCB that is 1.6mm thick. The
Ericsson P/N for the PCB assembly is 128 2311/1 R1C and the board is called the
Combined SPD. There are two 6-pin connectors [Component ID 5] for the input and
output of the circuit. The connector on the left in the diagram is the input while the
connector on the right is the output. There are five 90V surge arrestors [Component
ID 4] from EPCOS AG and three rectifiers [Component ID 3] from Fairchild
Semiconductor that form the basis of the over voltage protection circuit.