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A9.1.3 Derivation from a protection ratio

A9.1.3 Derivation from a protection ratio

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Last updated: Jan 10, 2018

This is the case for GSM, with regards to the 2 first adjacent channels.

In 3GPP TS 45 005  [21], Table 6.3-1 in section 6.3, protection ratios are specified in dB for a desensitisation DSTANDARD of 20 dB (see section 6.1).

  • Co-channel, [C/Ic]dB = C - Ic = 9 dB
  • First adjacent channel, [C/Ia1]dB = C - Ia1 = -9 dB
  • Second adjacent channel, [C/Ia2]dB= C - Ia2 = -41 dB

These are the “blocking protection ratios”.

The Blocking Response is given by the following equation:

Blocking Response    = IIB-STANDARD - IOOB-STANDARD    (Eq. 135)

= (C - IOOB-STANDARD) - (C - IIB-STANDARD)  (Eq. 136)

                               = (C - Ia) - (C - Ic)

IOOB-TARGET can then be derived from the following equation:

IOOB-TARGET = N + 10.log10[10^(DTARGET/10) - 1] + (C - Ic) - (C - Ia)   (Eq. 137)

IOOB-TARGET = N + I/NTARGET + (C - Ic) - (C - Ia)   (Eq. 138)