Blocking performance estimate for multi-mode receivers

[merit_ww]

Hi,

I confronted with a question like this：

For a dedicated multi-mode receivers (GSM/UMTS).

How the blocking performance would be like if both the wanted signal for GSM and UMTS are degraded by 3dB from it's minimum sensitivity.

The interference signal would be same .

What scenario could endure a larger inteference? GSM ? or Umts ?

Thanks

 

[RCinFLA]

If the interference signal is the same the GSM would be more vulerable then the WCDMA due to its narrow bandwidth and GMSK signalling so the UMTS would have inferior blocking performance if it reacted with the same 3 db degradation.

 

[merit_ww]

So you mean UMTS is worse than GSM in this scenario blocking performance ?

I got a result that UMTS can have better blocking performance than GSM :

The same receiver : both GSM/UMTS absolute sensitivity degrade by 3dB.

 

[vfone]

Have to be careful when compare blocking of GSM and UMTS, because they use not only different test bandwidths, but also different blocking levels (for both, inband and outband).
Also the absolute value of the desired signal (RFSENS +3dB) is different in GSM and UMTS.

 

[merit_ww]

Yes,vfone
Thank you .

In my scenario, I want to check whether there's an estimate method to verify :

Assume: The same MSR receivers ,with GSM minimum sensitivity -104dBm/200kHz, and UMTS sensitivity -115dBm.

So, estimate the blocking performance ,with GSM wanted signal -104+3=-101dBm, and UMTS wanted signal -115+3=-112dBm.

irrespective of LO phase, which would endure a larger jammer level?

Thanks

Have to be careful when compare blocking of GSM and UMTS, because they use not only different test bandwidths, but also different blocking levels (for both, inband and outband).
Also the absolute value of the desired signal (RFSENS +3dB) is different in GSM and UMTS.

 

[vfone]

First of all for blocking test RFSENS+3dB in GSM is -99dBm (in 200kHz BW) and in WCDMA is -103.7dBm (in 3.84MHz BW).

There is an equation to find the receiver Blocking Level function of SNR, BW, and Interferer Phase Noise at particular offset.
BlockingLevel[dBm] = (RFSENS+3dB)[dBm] - SNR[dB] - 10*LOG(BW)[Hz] - InterfererPhaseNoise@Offset[dBc/Hz]

In this equation if you keep constant the Interferer Phase Noise and change only the SNR and BW (which are different in GSM and WCDMA) you will see that wider BW (WCDMA case) support lower blocking level, when GSM (narrow BW) support stronger interferer with the same phase noise.
Meantime, lower SNR (WCDMA case) support stronger blocking interferer compare to GSM (higher SNR) which support lower blocking level with the same phase noise.

Also keep in mind there are different blocking requirements, some of them CW interferer, some modulated interferer. For modulated ones you get in top of the phase noise issue, an adjacent channel like issue.

 

[D.A.(Tony)Stewart]

is this any help? https://books.google.ca/books?id=iF...AHL9fX2CA&ved=0CB4Q6AEwAA#v=onepage&q&f=false

 

[zhlc3]

First of all for blocking test RFSENS+3dB in GSM is -99dBm (in 200kHz BW) and in WCDMA is -103.7dBm (in 3.84MHz BW).

There is an equation to find the receiver Blocking Level function of SNR, BW, and Interferer Phase Noise at particular offset.
BlockingLevel[dBm] = (RFSENS+3dB)[dBm] - SNR[dB] - 10*LOG(BW)[Hz] - InterfererPhaseNoise@Offset[dBc/Hz]

In this equation if you keep constant the Interferer Phase Noise and change only the SNR and BW (which are different in GSM and WCDMA) you will see that wider BW (WCDMA case) support lower blocking level, when GSM (narrow BW) support stronger interferer with the same phase noise.
Meantime, lower SNR (WCDMA case) support stronger blocking interferer compare to GSM (higher SNR) which support lower blocking level with the same phase noise.

Also keep in mind there are different blocking requirements, some of them CW interferer, some modulated interferer. For modulated ones you get in top of the phase noise issue, an adjacent channel like issue.

is there any quantization analysis on the Rx blocking and desensitization?