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Generate a Test Model

The LTE specifications define conformance test models for transmitter tests. These tests include transmit signal quality, output power dynamics, EVM for various modulation schemes, BS output power, and RS absolute accuracy. These different test models waveforms can be generated using functions in the LTE System Toolbox™ product.

E-UTRA Test Models

All E-UTRA test models (E-TMs), as defined in clause 6 of [1], use the following general parameters.

  • Single antenna port, 1 code word, 1 layer without any precoding

  • Duration is 10 subframes (10 ms)

  • Normal cyclic prefix

  • Virtual resource blocks of localized type

  • UE-specific reference signals are not used

The following physical channels and signals are generated.

  • Reference signals (CellRS)

  • Primary Synchronization signal (PSS)

  • Secondary Synchronization signal (SSS)

  • Physical broadcast channel (PBCH)

  • Physical control format indicator channel (PCFICH)

  • Physical hybrid ARQ indicator channel (PHICH)

  • Physical downlink control channel (PDCCH)

  • Physical downlink shared channel (PDSCH)

Test models are selected according to the required test case. In this example, the test model under consideration, E-TM1.1, is used to test the following criteria.

  • BS output power

  • Unwanted emissions

    • Occupied bandwidth

    • ACLR

    • Operating band unwanted emissions

    • Transmitter spurious emissions

  • Transmitter intermodulation

  • Reference signals absolute accuracy

Generate Test Model Waveform

This example shows how to generate a test model waveform, a time-domain (post-OFDM modulation) signal for a single antenna port and 10 subframes.

Specify, as a string, the test model number. In this example, generate test model 1.1. Test model 1.1 and other test models are defined in TS 36.141 [1], Section 6.

tm = '1.1';

Valid test model values are '1.1', '1.2', '2', '3.1', '3.2', and '3.3'.

Specify, as a string, the channel bandwidth. Select a non-standard bandwidth of 9 RB.

bw = '9RB';

Valid bandwidth values are '1.4MHz', '3MHz', '5MHz', '10MHz', '15MHz', '20MHz', '9RB', '11RB', '27RB', '45RB', '64RB', and '91RB'.

Generate the test model waveform.

[timeDomainSig,grid] = lteTestModelTool(tm,bw);

The channel model number and the bandwidth determine the physical channel and signal parameters, as specified in TS 36.141 [1]. The generated waveform, timeDomainSig, is a time-domain signal that has undergone OFDM modulation, cyclic prefix insertion, and windowing. The second output, grid, is a 2-dimensional array representing the resource grid spanning 10 subframes.

References

[1] 3GPP TS 36.141. “Base Station (BS) conformance testing.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA). URL: http://www.3gpp.org.

See Also

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