H.2 E-OTD LMU Requirements
3GPP45.005GSM/EDGE Radio transmission and receptionTS
An E-OTD Location Measurement Unit (LMU) is a unit that makes accurate observed time difference measurements of signals from BTSs. Specifically, the LMU shall be capable of measuring the Time-of-Arrival of bursts transmitted from a BTS on a periodic and predictable basis. The measurement results are used by the system for determining location of a MS. This clause defines the requirements to be put on the receiver of an LMU deployed in the GSM System. Requirements are defined for the E-OTD measurement accuracy of the LMU.
H.2.1 LMU Characteristics
In this clause, the requirements are given in terms of power levels at the antenna connector of the E-OTD LMU. Equipment with an integral antenna may be taken into account in a similar manner as described in Chapter 5 of 3GPP TS 45.005.
H.2.1.1 Blocking characteristics
This subclause defines E-OTD LMU receiver blocking requirements. The reference sensitivity performance as specified in table H.2-2 shall be met when the following signals are simultaneously input to the LMU.
– A neighbour BCCH carrier as described in H.2.2.1 at frequeny fo, 11 dB above the reference sensitivity level as specified in Table H.2-1.
– A continuous static sine wave signal as described in Section 5.1 of 3GPP TS 45.005. For GSM 400 and GSM 900, the requirements for "other MS" shall be used. For GSM 700, GSM 850, DCS 1800 and PCS 1900, the requirements for "MS" shall be used.
The exceptions listed in Section 5.1 of 3GPP TS 45.005 apply also for the E-OTD LMU requirements.
H.2.1.2 AM suppression characteristics
This subclause defines AM suppression requirements. The reference sensitivity performance as specified in Table H.2-2 shall be met when the following signals are simultaneously input to the LMU.
– A neighbour BCCH carrier as described in subclause H.2.2.1 at frequency fo, 11 dB above the reference sensitivity level as specified in table H.2-1.
– A single frequency signal as described in subclause 5.2 of 3GPP TS 45.005. The requirements for "MS" shall be used.
H.2.1.3 Intermodulation characteristics
This subclause defines intermodulation requirements. The reference sensitivity performance as specified in Table H.2-2 shall be met when the following signals are simultaneously input to the LMU.
– A neighbour BCCH carrier as described in subclause H.2.2.1 at frequency f0, 11 dB above the reference sensitivity level as specified in table H.2-1.
– A continuous static sine wave signal and any 148-bit subsequence of the 511-bits pseudo-random sequence in CCITT Recommendation O.153, as described in subclause 5.3 of 3GPP TS 45.005.
H.2.2 Sensitivity and Interference Performance
This clause specifies the required E-OTD measurement accuracy of the LMU with and without interference. The requirements are given in terms of E-OTD measurement error (in microseconds), as function of the carrier and interference input power levels, at the antenna connector of the receiver. Equipment with an integral antenna may be taken into account in a similar manner as described in clause 5 of 3GPP TS 45.005.
The power level, under multipath fading condition, is the mean power of the sum of the individual paths.
H.2.2.1 Sensitivity Performance
With the following configuration and propagation conditions, the LMU shall meet the requirements of 90% RMS E-OTD error defined in table H.2-2.
– The E-OTD LMU receives a reference BCCH carrier with a power level of 28 dB above the reference sensitivity level defined in table H.2-1.
– The E-OTD measurements (relative to the reference BCCH carrier) are done on a neighbour BCCH carrier at power levels relative to the reference sensitivity level defined in Table H.2-1. The measurement power levels are given in Table H.2-2.
– The network requests an E-OTD measurement by commanding the LMU to report the E-OTD measurement with shortest possible reporting period (see 3GPP TS 44.071 Annex A).
– The measurement performance shall also be achieved with the reference BCCH and the neighbour BCCH carriers having 8-PSK, QPSK, 16-QAM or 32-QAM modulated bursts. 8-PSK, QPSK, 16-QAM and 32-QAM modulation and the 8-PSK, QPSK, 16-QAM and 32-QAM normal bursts are defined in 3GPP TS 45.004 clause 3 and 3GPP TS 45.002 subclause 5.2.3, respectively.
– The measurement accuracy of the LMU is defined as the root-mean-square (RMS) value of 90% of the measurements that result in the least E-OTD error. As an example, if {x1..xN}is a set of the absolute square E-OTD measurement errors for N trials, sorted in ascending order, the RMS of 90% is defined as:
RMS90 = sqrt( sum(x1..xM)/M )
– where M is the largest integer such that M < 0,9 N. For the test, N > 250 trials is recommended . The channels shall be static, i.e. at a constant signal level throughout the measurements.
Table H.2-1: Reference Sensitivity Level
|
Signal strength at antenna connector |
|
|
GSM 400, GSM850, GSM 900, DCS 1800, PCS 1900 |
-110 dBm |
Table H.2-2: Sensitivity performance
(RMS90 of E-OTD error in microseconds)
|
Minimum neighbour carrier signal strength relatively to E-OTD LMU reference sensitivity level (Table H.2–1) |
Static channel |
|
0 dB |
0.3 s |
|
20 dB |
0.1 s |
H.2.2.2 Interference Performance
This clause defines E-OTD measurement accuracy (in microseconds) for specified carrier-to-interference ratios of the neighbor BCCH carrier. The reference BCCH carrier is as defined in subclause H.2.2.1. The neighbour BCCH carrier shall be as defined in H.2.2.1 and shall be set to a level 28 dB above the reference sensitivity level defined in table H.2-1. The C/I requirements shall be met for an interference signal which is co-channel, adjacent channel (200 kHz offset), and alternate channel (400 kHz offset) to the desired neighbour BCCH carrier as shown in table H.2-3.
– The interference signal consists of a random, continuous GMSK modulated signal.
Table H.2-3: Interference performance
(RMS90 of E-OTD error in microseconds)
|
Interference type |
Static channel |
Minimum carrier to Interference Level (dB) |
|
Co-channel |
0.3 s |
0 dB |
|
0.1 s |
10 dB |
|
|
Adjacent channel |
0.5 s |
-18 dB |
|
0.2 s |
-8 dB |
|
|
Adjacent channel |
0.1 s |
-41dB |
H.2.2.3 Multipath Performance
This clause defines E-OTD measurement accuracy under multipath conditions. The test setup is as under subclause H.2.2.1 (sensitivity performance) with the following changes:
– Each burst of the neighbour BCCH carrier propagates through the TU multipath channel specified in annex C of 3GPP TS 45.005. The reference carrier remains static.
The performance requirements are specified in table H.2-4.
Table H.2-4: Multipath performance
(RMS90 of E-OTD error in microseconds)
|
Minimum neighbour carrier signal strength relative to reference sensitivity (Table H.2-1) |
TU3 |
|
0 dB |
1,5 s |
Annex I (normative):
E-OTD Mobile Station Requirements