User's Manual

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D-620616-0-20 Rev C CONFIDENTIAL
Fusion Wideband Installation Procedures
800/850 MHz Isolation Requirements
When deploying any RF system, give special attention to preventing receiver block-
ing or desensitization by out-of-band transmitters. Typically, sharp filters in the
receiver front-end will reduce the interfering transmitters to tolerable levels. In select
cases, the interferers may occupy a frequency band that is directly adjacent to the
receiving band and cannot be adequately rejected by filtering. The only recourse in
these situations is to provide sufficient isolation by physically separating the interfer-
ing transmitters and receivers.
iDEN occupies spectrum at both 800 MHz and 900 MHz (Tx:851–869/Rx:806–824
and Tx:935–941 /Rx:896–902), while the Cellular A and B carriers share a single 850
MHz block (Tx:869–894/Rx:824–849). The combination of these frequency bands,
800/900 MHz iDEN and 850 MHz Cellular, result in uplink (BTS receive) bands that
are adjacent to downlink (BTS transmit) bands. Figure 7-19 depicts these nearly con-
tiguous bands, with arrows indicating the interfering downlink and receiving uplink
bands.
Figure 7-19 800/850 MHz Spectrum
Installation of an in-building distributed antenna system (DAS) to provide coverage
for both 800/900 MHz iDEN and 850 MHz Cellular must account for these down-
link-to-uplink interference issues and provide adequate isolation.
ADC offers the following guidelines toward achieving the proper amount of isolation
when deploying ADC Fusion DAS products.
Figure 7-20 Fusion Wideband 800/850/1900 MHz RAU Antenna Placement
Guideline
850
850
896-902
>d
Band 1
800 MHz
Band 2/3
850/1900 MHz