Co-location, Isolations
Spurious emissions are emissions, which are caused by unwanted transmitter effects such as harmonics emission, parasitic emission, intermodulation products and frequency conversion products, but exclude out of band emissions. This is measured at the base station RF output port.
Spectrum Emission Mask, 3GPP TS 25.104 Fig. 6.2
Spurious emissions limits for protection of the BS receiver
The table above corresponds to -80 dBm / 3.84MHz spurious emission requirements from UMTS DL to UMTS UL.
EXAMPLE
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Spurious emission DL to UL
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- 80 dBm
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See above
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Max sensitivity degradation
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- 121 dBm
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BS reference sensitivity
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Min required isolation
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41 dB
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UMTS FDD isolation requirement due to spurious emissions
Note: Check with your vendor, they will quote a lower figure
The receiver blocking characteristics is a measure of the receiver ability to receive a wanted signal at its assigned channel frequency in the presence of an unwanted interferer on frequencies other than those of the adjacent channels.
EXAMPLE
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Max Node B power
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43 dBm
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= 20W
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Blocking level
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- 40 dBm
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3GPP 25104 7.5.1
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Min required isolation
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83 dB
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UMTS FDD - FDD isolation requirement due to receiver blocking
Note: Check with your vendor, they will quote a lower figure
The transmit intermodulation performance is a measure of the capability of the transmitter to inhibit the generation of signals in its non linear elements caused by presence of the wanted signal and an interfering signal reaching the transmitter via the antenna. The transmit intermodulation level shall not exceed the out of band emission or the spurious emission requirements.
Summary: Co-location and isolation related issues
Co-location issues; base station receivers; spurious emission and blocking
Co-existence issues; mobile phone receivers; spurious emission and blocking
Intermodulation issues
All wireless systems need to be considered
Vendor equipment specification far better that 3GPP specifications
Solution considerations
Equipment specifications
Horisontal antenna separation
Vertical antenna separation
Additional filtering
Antenna beamwidth
Antenna bearing
Frequency coordination with other carriers
Smart designs for common antenna systems
Further reading: 3GPP TS 25.104, GSM 05.05, ITU-R SM.329-9
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