6.3 Reference interference level

05.053GPPRadio transmission and receptionTS

The reference interference performance (for cochannel, C/Ic, or adjacent channel, C/Ia) in terms of frame erasure, bit error or residual bit error rates (whichever appropriate) is specified in table 2, according to the type of channel and the propagation condition. The performance requirements for GSM 400 systems are as for GSM 900 in table 2, except that the GSM 400 MS speed is doubled from that of GSM 900, e.g. TU50 becomes TU100. The actual interference ratio is defined as the interference ratio for which this performance is met. The actual interference ratio shall be less than a specified limit, called the reference interference ratio. The reference interference ratio shall be, for BTS and all types of MS:

for cochannel interference

C/Ic

=

9 dB

for adjacent (200 kHz) interference

C/Ia1

=

‑9 dB

for adjacent (400 kHz) interference

C/Ia2

=

‑41 dB

for adjacent (600 kHz) interference

C/Ia3

=

‑49 dB

For GMSK modulated channels, packet switched and ECSD, and for 8-PSK modulated channels, packet switched and ECSD, the minimum interference ratio for which the reference performance for cochannel interference (C/Ic) shall be met is specified in table 2a, 2d and 2e (GMSK), 2b and 2c, 2d and 2e (8-PSK) respectively, according to the type of channel, the propagation condition and type of equipment. The performance requirements for GSM 400 systems are as for GSM 900 in table 2a, 2b, 2c, 2d and 2e except that the GSM 400 MS speed is doubled from that of GSM 900, e.g. U50 becomes TU100. The reference performance is the same as defined in subclause 6.2. For equipment supporting 8-PSK, the requirements apply for both GMSK and 8-PSK modulated interfering signals. The corresponding interference ratio for adjacent channel interference shall be:

Modulation of wanted signal

GMSK

8-PSK

for adjacent (200 kHz) interference

C/Ia1

=

C/Ic ‑ 18 dB

see table 2f, 2g, 2h and 2i

for adjacent (400 kHz) interference

C/Ia2

=

C/Ic ‑ 50 dB

C/Ic –50 dB

for adjacent (600 kHz) interference

C/Ia3

=

C/Ic ‑ 58 dB

C/Ic –58 dB

NOTE: The C/Ia3 figure is given for information purposes and will not require testing. It was calculated for the case of an equipment with an antenna connector, operating at output power levels of +33 dBm and below. Rejection of signals at 600 kHz is specified in subclause 5.1.

The values in tables 2f, 2g, 2h and 2i are also valid for GSM 400 with the exception that MS speed is doubled, e.g. TU50 becomes TU100.

These specifications apply for a wanted signal input level of 20 dB above the reference sensitivity level, and for a random, continuous, GSM‑modulated interfering signal. For packet switched, GMSK modulated channels the wanted input signal level shall be: -93 dBm + Ir + Corr, where:

Ir = the interference ratio according to table 2a
Corr = the correction factor for reference performance according to subclause 6.2.

For ECSD channels and 8-PSK modulated packet-switched channels, the wanted input signal level shall be: – 93 dBm + Ir + Corr, where:

Ir = the interference ratio according to table 2b and 2c for packets switched channels and table 2d and 2e for ECSD
Corr = the correction factor for reference performance according to subclause 6.2

In case of frequency hopping, the interference and the wanted signals shall have the same frequency hopping sequence. In any case the wanted and interfering signals shall be subject to the same propagation profiles (see annex C), independent on the two channels.

For a GSM 400 MS, a GSM 900 MS, a GSM 850, a DCS 1 800 MS and a PCS 1 900 MS the reference interference performance according to table 2 for co‑channel interference (C/Ic) shall be maintained for RA500/250/130 propagation conditions if the time of arrival of the wanted signal is periodically alternated by steps of 8µs in either direction. The period shall be 32 seconds (16 seconds with the early and 16 seconds with the late time of arrival alternately).

For pico-BTS, propagation conditions other than static and T15 are not specified and only the no FH case need be tested. The performance requirement for GSM 900, GSM 850, DCS 1 800, PCS 1900, MXM 850 and MXM 1900 pico-BTS with TI5 propagation condition is the same as theTU50 no FH (900MHz) performance requirement. The interference ratio at which this requirement shall be met is, for GMSK modulated wanted signals, 4dB above the interference ratio specified above in this sub-clause (in combination with Table 2a for packet service). For 8-PSK modulated wanted signals, the interference ratio for this requirement is 4 dB above the interference ratio specified above in this sub-clause (in combination with Table 2b, 2c, 2d and 2e for packet service). For adjacent channel interference propagation conditions other than TU50 need not be tested. There is an exception in the case of the pico-BTS in that the specified propagation condition is TI5 instead of TU50; the respective test for pico-BTS is described in the paragraph following the table below. If, in order to ease measurement, a TU50 (no FH) faded wanted signal, and a static adjacent channel interferer are used, the reference interference performance shall be:

GSM 850 & GSM 900

DCS 1 800 & PCS 1 900

TCH/FS (FER):

10,2 %

5,1 %

Class Ib (RBER):

0,72/ %

0,45/ %

Class II (RBER):

8,8 %

8,9 %

FACCH (FER):

17,1 %

6,1 %

For pico-BTS, adjacent channel and cochannel interference propagation conditions other than TI5 need not be tested. If, in order to ease adjacent channel measurements, a TI5 (no FH) faded wanted signal, and a static adjacent channel interferer are used, the interference performance shall be the same as that specified above for a TU50 no FH channel (900MHz). The interference ratio at which this performance shall be met is 4dB above the reference interference ratio specified above in this sub-clause.