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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.

emission mask

Spectrum Emission Mask, 3GPP TS 25.104 Fig. 6.2

Spurious_emissions_DL_to_UL

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

Spurious emission DL to UL
- 80 dBm
  See above
Max sensitivity degradation
- 121 dBm
  BS reference sensitivity
Min required isolation
 41 dB
  

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

Max Node B power
  43 dBm
  = 20W
Blocking level
- 40 dBm
  3GPP 25104 7.5.1
Min required isolation
 83 dB
  

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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