7.1 Static Layer 1 receiver functions (nominal error ratios)

11.213GPPBase Station System (BSS) equipment specificationRadio aspectsRelease 1999TS

7.1.1 Test Purpose

The static Layer 1 receiver functions verified in these tests are the RF parts, the multiplexing and multiple access functions, any existing equalizer, the deciphering functions, the de‑interleaving and the channel decoding on the receive side. The performance of the receiver at the maximum specified input level is also verified.

Nominal error ratios (Bit Error Ratio ‑ BER) are measured at a logical reference point that represents the performance before channel decoding. This measurement can be performed for TCH/FS, using unprotected class II bits extracted after channel decoding, but before any extrapolation. Therefore, the results obtained are representative of the logical reference point before channel decoding. The test can also be performed on the uncoded bits extracted before any channel decoding of a PDTCH channel.

If the BTS supports SFH, this test also verifies the TCH/FS performance in frequency hopping under interference conditions. In this case, the Frame Erasure Ratio (FER) for TCH/FS is used as the performance criteria.

The Random access performance at high input levels is verified by measuring the Frame Erasure Ratio for RACH.

7.1.2 Test Case

GMSK modulation

1) For BER measurements, if Slow Frequency Hopping (SFH) is supported by the BSS, the BSS shall be hopping over the maximum range and number of ARFCNs possible for the test environment and which are available in the BSS configuration. If SFH is not supported, the test shall be performed for the radio frequency channels B, M and T. In both cases the tests shall be repeated until all the RF equipment in the BSS configuration is tested on all specified carrier frequencies.

If test is performed with TCH/FS a test signal with normal TCH/FS modulation originating from the BSSTE shall be applied to the BSS receiver input. The unprotected class II bits obtained from the BSS receiver after channel decoding and before any extrapolation shall be compared with the unprotected class II bits originating from the BSSTE.

If test is not performed with TCH/FS a test signal with normal PDTCH modulation originating from the BSSTE shall be applied to the BSS receiver input. The uncoded data bits obtained from the BSS receiver shall be compared with the bits originating from the BSSTE.

NOTE: Uncoded data bits refer to the encrypted bits of a burst, extracted by the receiver without any signal processing improvement from encoding/decoding of the signal.

The test shall be performed at the following power levels of test signal:

a) A lower limit (20 dB above the reference sensitivity level of the BSS under test), as specified in table 12, for static propagation conditions.

b) ‑40 dBm, for static propagation conditions.

  1. ‑15 dBm for GSM 400, GSM900, GSM850 and MXM 850 and ‑23 dBm for DCS1800, PCS 1900 and MXM 1900, for static propagation conditions only.

d) -5 dBm for GSM900, GSM850 and MXM 850 pico-BTS and -14 dBm for DCS1800, PCS 1900 and MXM 1900 pico-BTS, for static propagation conditions only.

e) A lower limit (20 dB above the reference sensitivity level of the BSS under test), as specified in table 12, for EQ50 propagation conditions, except for GSM 400 where EQ100 applies step e) does not apply to pico-BTS).

f) -40dBm, for EQ50 propagation conditions, except for GSM 400 where EQ100 applies step f) does not apply to pico-BTS).

2) For RACH, the test shall be performed for the radio frequency channels B, M and T. A test signal consisting of RACH bursts originating from the BSSTE shall be applied to the BSS receiver input. The proportion of RACH bursts at the input to the receiver which are not correctly identified by the BSS shall be measured.

The test shall be performed at the following power levels of test signal:

a) A lower limit (20 dB above the reference sensitivity level of the BSS under test), as specified in table 12, for static propagation conditions.

b) ‑40 dBm, for static propagation conditions.

c) ‑15 dBm for GSM 400, GSM900, GSM850 and MXM 850 and ‑23 dBm for DCS1800, PCS 1900 and MXM 1900 for static propagation conditions.

3) For TCH/FS FER measurements in frequency hopping under interference conditions, two signals are connected to the BSS receiver input via a combining network. The wanted signal with an RF level given in table 12 shall be cyclically frequency hopping on four carrier frequencies under static conditions. The interfering signal shall be a random continuous, GMSK-modulated signal on only one of the carriers at a level 10 dB higher than the wanted signal.

The test shall be performed with the hopping frequencies centered around RF channel M.

8-PSK modulation

1) If Slow Frequency Hopping (SFH) is supported by the BSS, the BSS shall be hopping over the maximum range and number of ARFCNs possible for the test environment and which are available in the BSS configuration. If SFH is not supported, the test shall be performed for the radio frequency channels B, M and T. In either cases the tests shall be repeated until all the RF equipment in the BSS configuration is tested on all specified carrier frequencies.

A test signal with normal modulation originating from the BSSTE shall be applied to the BSS receiver input. The uncoded data bits obtained from the BSS receiver shall be compared with the bits originating from the BSSTE.

NOTE: Uncoded data bits refer to the encrypted bits of a burst, extracted by the receiver without any signal processing improvement from encoding/decoding of the signal.

The test shall be performed at the following power levels of test signal:

  1. A lower limit level, as specified in table 12, for static propagation conditions.
  2. –40dBm, for static propagation conditions.
  3. The maximum limit as specified in table 12, for static propagation conditions.
  4. Step a and b shall be repeated with the frequency of the input 8-PSK modulated signal randomly offset, by +-0,1 ppm (except +-0,2 ppm for GSM400), on a burst-by-burst basis. For each burst, the sign of the frequency offset is chosen according to a 511-bit pseudo-random sequence, defined in ITU-T recommendation O.153.

Table 12: Limit of RF input for testing of Static Layer 1 receiver functions

BTS Type

Lower Limit

GMSK and 8-PSK

Maximum Limit

8-PSK

GSM 400/GSM850/GSM900/DCS1800/PCS 1900/MXM 850/MXM 1900 BTS

‑84 dBm

-26 dBm

GSM900/GSM850/MXM 850 micro‑BTS M1

‑77 dBm

-24 dBm

GSM900/GSM850/MXM 850 micro‑BTS M2

‑72 dBm

-19 dBm

GSM900/GSM850/MXM 850 micro‑BTS M3

‑67 dBm

-14 dBm

GSM900/GSM850/MXM 850 pico‑BTS P1

-68 dBm

-16 dBm

DCS1800/PCS 1900/ MXM 1900 micro‑BTS M1

‑82 dBm

-24 dBm

DCS1800/PCS 1900/ MXM 1900 micro‑BTS M2

‑77 dBm

-19 dBm

DCS1800/PCS 1900/ MXM 1900 micro‑BTS M3

‑72 dBm

-14 dBm

DCS1800/PCS 1900/ MXM 1900 pico-BTS P1

-75 dBm

-17 dBm

7.1.3 Essential conformance

This test need not be performed.

7.1.4 Complete conformance

Test Environment:

Normal: For GMSK BER measurements, each TRX shall be tested.

For RACH, the TRX supporting the BCCH shall be tested.

For 8-PSK modulation, each TRX shall be tested. Any 8-PSK modulated channel type can be used.

Extreme Temperature: For GMSK BER measurements, one TRX shall be tested on one timeslot, for static propagation conditions only.

For RACH, the TRX supporting the BCCH shall be tested.

For TCH/FS FER measurements, the test need not be performed.

For 8-PSK modulation, one TRX shall be tested on one timeslot, for static propagation conditions only. Any 8-PSK modulated channel type can be used.

Vibration: For GMSK BER measurements, one TRX shall be tested on one timeslot, for static propagation conditions only.

For TCH/FS FER measurements in frequency hopping under interference conditions and for RACH, the test need not be performed.

For 8-PSK modulation, one TRX shall be tested on one timeslot, for static propagation conditions only. Any 8-PSK modulated channel type can be used.

Conformance Requirement

The bit error ratio of the unprotected bits (TCH/FS, Class II or uncoded PDTCH bits) shall not exceed:

Static propagation conditions BER 10‑4 For input levels up to ‑40 dBm

Static propagation conditions BER 10‑3 For input levels > ‑40 dBm

EQ50 (except for GSM400, where EQ100 applies) propagation conditions BER 3 %

The FER of TCH/FS under interfering conditions shall not exceed 5 %.

The frame erasure ratio of the RACH shall not exceed 0.5%.

The bit error ratio of uncoded data bits in 8-PSK channels shall not exceed:

Static propagation conditions (steps a, b and d) BER 10‑4 for input levels up to 40 dBm.

Static propagation conditions (step c) BER 10‑3 for input levels > ‑40 dBm.

7.1.5 Requirement Reference

GSM 05.05 (EN 300 910) [22] subclause 6.1, subclause 6.5 and subclause 6.6.