7.2 Erroneous Frame Indication Performance

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

7.2.1 Test Purpose

In GSM 05.03 (EN 300 909) [20] a Cyclic Redundancy Check (CRC) is defined for detection of erroneous Layer 2 frames or speech frames. For speech channels also additional error detecting capabilities using some soft information are needed due to DTX operation when no useful signal is transmitted to the receiver. This test verifies the reliability of the overall Bad Frame Indication (BFI) presented to the speech decoder and the Frame Erasure Indication (FEI) used on control channels.

7.2.2 Test Case

1) A test signal consisting of continuous GSM modulation of a pseudo random bit stream without mid‑amble, and at a level specified in table 13, shall be applied to the receiver antenna connector, on the same frequency as the TRX under test.

One TRX shall be configured to support a BCCH. The detection by the BSS of error‑free RACH bursts (FEI=0) shall be monitored by the BSSTE. If both GPRS is supported by the BSS and a PBCCH can be configured, then the detection by the BSS of error-free PRACH bursts (FEI=0) shall be monitored by the BSS.

Table 13: Test Signal input level for testing of Erroneous Frame Indication performance

BTS Type

Test signal Input Level

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

‑84 dBm

GSM900/GSM850/MXM 850 micro‑BTS M1

‑77 dBm

GSM900/GSM850/MXM 850 micro‑BTS M2

‑72 dBm

GSM900/GSM850/MXM 850 micro‑BTS M3

‑67 dBm

GSM900/GSM850/MXM 850 pico-BTS P1

-68 dBm

DCS1800/PCS 1900/ MXM 1900 micro‑BTS M1

‑82 dBm

DCS1800/PCS 1900/ MXM 1900 micro‑BTS M2

‑77 dBm

DCS1800/PCS 1900/ MXM 1900 micro‑BTS M3

‑72 dBm

DCS1800/PCS 1900/ MXM 1900 pico-BTS P1

-75 dBm

2) Step 1 shall be repeated without any RF input on the TRX under test, with the receiver antenna connector terminated with 50W.

3) Step 1 shall be repeated with one timeslot on one TRX configured for TCH/FS, TCH/HS, TCH/EFS, TCH/AxS and for FACCH. The Bad Frame Indication (BFI) shall be monitored by the BSSTE.

  1. Step 3 shall be repeated without any RF input on the TRX under test, with the receiver antenna connector terminated with 50W.
  2. The test shall be repeated with one timeslot on one TRX configured for TCH/FS, TCH/HS, TCH/EFS and TCH/AxS, when DTX is activated with SID frames and SACCH frames received at a level specified in table 13 and with no transmission at the other bursts of the TCH. The Bad Frame Indication (BFI) shall be monitored by the BSSTE.

7.2.3 Essential conformance

This test need not be performed.

7.2.4 Complete conformance

Test Environment:

Normal.

Conformance requirement

In steps 1 and 2, less than 0.02 % of the frames shall be detected as error free (FEI=0).

In steps 3, 4 and 5, less than 1 undetected bad speech frame (i.e. detected as BFI=0) shall occur on average in a period of 60 s.

7.2.5 Requirement reference

GSM 05.05 (EN 300 910) [22] subclause 6.4.