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LTE UE RF Conformance Tests

This page describes LTE UE RF Conformance Tests. These tests have been divided into following sub-categories.
•  RF Transmitter tests
•  RF Receiver tests
•  RF performance tests

LTE Transmitter and receiver tests are defined in 3GPP TS 36.521. These transmitter tests are very useful in LTE device testing. LTE transmitter tests are divided into power measurements(transmit power and output power dynamics), signal quality measurements(frequency error and modulation tests(EVM,carrier leakage,spectral flatness) and spectrum measurements(spurious emissions, ACLR, spectrum emission mask,occupied bandwidth). The test cases for this LTE conformance tests are mentioned below along with the specification limit specified in the standard 3GPP TS 36.521.

RF Transmitter part tests for LTE UE

Test Case Specification/Limit
UE Maximum output power Measured as the mean power in one sub-frame , +23 dBm with +/- 2 dB tolerance for LTE UE power class-3 devices for E-UTRA band 1 to 40 (Ref: section 6.2.2)
Maximum power reduction(MPR) This test applies to all types of E-UTRA UE release 8 and forward. For UE Power Class 3, the allowed MPR values for the maximum output power is as follows.
For QPSK for difference bandwidths(1.4,3,5,10,15,20) MPR is <= 1dB
For 16QAM for above bandwidths there are two limits i.e. <=1 dB and <=2 dB as per RBs allocated. (Ref.section: 6.2.3)
Power control Power control helps to limit the interference level and is useful to compensate the channel fading. There are three different specifications in this test case viz. Power control absolute power tolerance (+/-9 dB under normal conditions and +/-12 dB under extreme conditions) , power control relative power tolerance and Aggregate power control tolerance. (Ref. section: 6.3.5)
Minimum output power Measured as the mean power in one sub-frame (i.e. 1ms) -40 dBm for difference channel bandwidths(1.4/3/5/10/15/20 MHz) ,(Ref. section:6.3.2)
Transmit OFF Power The LTE UE Transmit OFF power is defined as the mean power when the transmitter is OFF. During frame measurements gaps, the UE is not considered to be OFF. The transmitter is considered to be OFF when the UE is not allowed to transmit or during periods when the UE is not transmitting a LTE subframe. It is -48.5 dBm for various channel BW/measurement BW combinations. (1.4MHz/1.08MHz, 3MHz/2.7MHz, 5MHz/4.5MHz, 10MHz/9MHz, 15MHz/13.5MHz, 20MHz/18MHz )
(section: 6.3.3)
Frequency error +/- 0.1 ppm observed over a period of one time slot (0.5 ms) compared to the carrier frequency received from the LTE eNodeB or base station. (section:6.5.1)
Min. Transmit Error Vector Magnitude(EVM) - It should not exceed values listed below.
For BPSK/QPSK: 17.5 dB (Average level), 17.5 dB(Ref.signal EVM level)
For 16QAM: 12.5 dB(Average level), 12.5 dB (Ref.signal EVM level)
EVM measurements are evaluated for 10 consecutive uplink sub-frames for the average EVM case,and 60 consecutive sub-frames for the reference signal EVM case.
(section: 6.5.2).
Occupied Bandwidth It is defined as the bandwidth containing 99% of the total integrated mean power of the transmitted spectrum on the assigned channel. Occupied bandwidth is the most fundamental LTE spectral emissions measurement. It should be less than values for different channel BWs as follows. 1.4MHz (for 1.4MHz channel BW),3MHz (for 3MHz channel BW), 5, 10, 15, 20 MHz. (section:6.6.1)
Spectrum Emission Mask The spectrum emission mask defines maximum power that the transmitter can emit in a defined bandwidth at a range of frequency offsets from the center channel. Frequency offsets ranging from 1 MHz to 25 MHz from the band edge is used for this LTE device testing. It uses a measurement bandwidth of 1 MHz. The spectrum emission values have been defined for different channel bandwidths (1.4/3/5/10/15/20 MHz). Close in measurements need to be measured with 30 KHz measurement BW. (section: 6.6.2.1)
ACLR (Adjacent channel leakage power ratio) This test case is used to verify that UE transmitter does not cause unacceptable interference to adjacent channels in terms of Adjacent Channel Leakage power Ratio(ACLR).
E-UTRA ACLR = (power in the center E-UTRA channel)/(power in an adjacent E-UTRA channel)

The ACLR value is 30 dB for different channel BW/measurement BW combinations (1.4 MHz /1.08 MHz, 3 MHz/2.7 MHz, 5/4.5, 10/9, 15/13.5, 20 MHz/18 MHz ) .
(section:6.6.2.3)
Transmitter spurious emissions spurious emission limits for various frequency ranges and measurement bandwidths are as follows:
For ( 9KHz<=f<150KHz and 1 KHz ) is -36 dBm
For ( 150KHz<=f<30 MHz and 10 KHz ) is -36 dBm
For ( 30 MHz<=f<1000 KHz and 100 KHz ) is -36 dBm
For ( 1GHz<=f<12.75 GHz and 1 MHz ) is -30 dBm
(section: 6.6.3.1 )
Transmit intermodulation The transmit intermodulation performance is a measure of the capability of the transmitter to inhibit the generation of signals in its non linear elements caused by presence of the wanted signal and an interfering signal reaching the transmitter via the antenna. The UE intermodulation attenuation is defined by the ratio of the mean power of the wanted signal to the mean power of the intermodulation product when an interfering CW signal is added at a level below the wanted signal at each of the transmitter antenna port with the other antenna port(s) if any is terminated.

BW channel (Uplink): 20 MHz
Interference signal frequency offset: 20 MHz, 40 MHz
Interference CW signal level: -40dBc
Intermodulation product: -35dBc
Measurement bandwidth: 18 MHz
Refer Table 6.7.3-1 in section:6.7 for other channel BWs


RF receiver part tests for LTE UE conformance

These receiver tests are very useful in LTE device testing. The receiver test cases for these LTE UE conformance tests are mentioned below.

Test Case 3GPP TS 36.521 description
Reference sensitivity level There are different levels specified for various E-UTRA bands for different channel BWs and duplex modes(FDD/TDD) as specified in the standard. For example: For EUTRA band 44, TDD mode: -100.2 dBm (3 MHz) , -98(5 MHz), -95(10 MHz), -93.2(15 MHz), -92 dBm (20 MHz)
( section 7.3)
Maximum input level The minimum conformance requirements for maximum input level necessitates that the receiver be able to achieve at least 95% of the maximum throughput in the presence of signal powers up to -25 dBm (for various channel BWs) .
(section: 7.4)
Adjacent channel selectivity LTE receiver Adjacent Channel Selectivity(ACS) for different transmission BWs are as follows.
ACS is 33 dB (for 1.4/3/5/10 MHz), 30 dB for 15 MHz and 27 dB for 20 MHz.
(section 7.5)
In-band blocking The blocking characteristic is a measure of the receiver's ability to appropriately demodulate LTE signals in the presence of a wide range of interference signals. In-band blocking is a metric of receiver performance in the presence of unwanted interfering signal falling into the UE receive band, or into the first 15 MHz below or above the UE receive band.
(section 7.6.1)
Out-of-band blocking The LTE receiver out-of-band band blocking characteristics are designed as a metric to evaluate receiver performance in the presence of higher power out-of band signals. Unlike the in-band blocking characteristics that use a modulated signal, the out-of-band interfering signal is a continuous wave (CW) signal.
(section 7.6.2)
Narrow band blocking Narrowband blocking is a metric of the LTE receiver's ability achieve minimum throughout in the presence of an unwanted narrow band interferer at a frequency offset that is less than the channel spacing. Similar to the out-ofband blocking characteristics, the narrowband blocking measurement requires a test configuration that uses both a vector signal generator and a CW signal generator.
(section 7.6.3)
Spurious response Narrowband blocking is a metric of the LTE receiver's ability achieve minimum throughout in the presence of an unwanted narrow band interferer at a frequency offset that is less than the channel spacing. Similar to the out-ofband blocking characteristics, the narrowband blocking measurement requires a test configuration that uses both a vector signal generator and a CW signal generator.
(section 7.7)
Wide Band Intermodulation Receiver intermodulation characteristics is a metric that describes the linearity of the receiver's front end. A receiver's resilience to intermodulation distortion is determined by injecting two interference signals in addition to a reference downlink LTE signal to the receiver. The frequency spacing of the two interfering signals is chosen such that they produce a third-order distortion product that directly interferes with the reference downlink signal.
(section 7.8.1)
Narrow Band intermodulation section 7.8.2
Spurious emissions Unlike most receiver measurements, which define a receiver's ability to achieve a specified throughput under a range of signal conditions, the spurious emissions measurement is designed to characterize the receive port's radiated emissions.
(section 7.9)

Performance conformance tests

The performance requirements for the various LTE physical channels under different configurations is specified in the 3GPP TS 36.521 document in section-8. These performance tests are used for LTE UE conformance tesing.

Test Case Standard reference/Description
PDSCH single antenna port performance 8.2.1.1(LTE,FDD)
8.2.2.1(LTE,TDD)
PDSCH Transmit diversity performance 8.2.1.2(LTE,FDD)
8.2.2.2(LTE,TDD)
PDSCH Open Loop spatial multiplexing performance 8.2.1.3(LTE,FDD)
8.2.2.3(LTE,TDD)
PDSCH closed loop spatial multiplexing performance 8.2.1.4(LTE,FDD)
8.2.2.4(LTE,TDD)
MU-MIMO 8.2.2.5
Control channel performance D-BCH PCH 8.2.2.6
Demodulation of PDSCH(User-Specific reference symbols) 8.3
PCFICH/PDCCH single antenna port performance 8.4.1.1(LTE,FDD)
8.4.2.1(LTE,TDD)
PCFICH/PDCCH transmit diversity performance 8.4.1.2 (LTE,FDD)
8.4.2.2(LTE,TDD)
Demodulation of PHICH 8.5
Demoduation of PBCH 8.6

               

LTE RELATED LINKS

Difference between SC-FDMA and OFDMA
LTE Cyclic Delay Diversity
LTE eNodeB Physical Layer Measurements
LTE EPC Network Inerfaces
LTE UE Physical Layer Measurements

RF and Wireless Terminologies


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