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.
