r&s®smw-九游官网下载
- 概览
- features & benefits
the lte harq feedback and uplink timing adjustment tests in line with the lte standard requires simulation of a signal scenario as shown below:
- lte closed-loop base station test
the recommended test setup for lte harq feedback and uplink timing adjustment tests with the r&s®smw200a is as follows:
- lte closed-loop base station test setup with the r&s®smw200a
the two r&s®smw200a baseband generators simulate the two ue signals with the appropriate fixed reference channels (frcs) by using the r&s®smw-k55 lte option. as defined in the test specification, one of the two ues is faded in accordance with the lte moving propagation fading profiles (ts 36.141, annex b4). this is accomplished with fading simulator options 2x r&s®smw-b14 r&s®smw-k74. the relevant lte fading profiles are available as predefined settings. the faded ue1 signal and the nonfaded ue2 signal are then fed to the awgn generators. after awgn is applied, the resulting signals are added up pairwise in the i/q stream mapper of the r&s®smw200a. finally the rf output signals are fed to the two rx ports of the base station. the base station uses receive diversity and recovers both ue signals (ue1 and ue2). depending on the signals received, the base station then changes the timing of ue1 relative to ue2 and sends the harq feedback (ack/nack) commands to both ues. the base station under test can use these commands to control the channel coding configuration (i.e. the redundancy version) of the transmitted pusch packets in realtime.
the behavior of the r&s®smw200a vector signal generator is similar to that of the harq entity/harq processes of real user equipment (in accordance with 3gpp ts 36.321). using adjustment/timing advance commands, the base station under test can request time shifts of the uplink signal generated by the signal generator and thus cause a delay or advance of the uplink signal in realtime (in accordance with 3gpp ts 36.213). timing adjustment commands and harq feedback are transmitted from the base station under test to the signal generator via a special serial feedback line. for harq feedback tests only, a simplified binary feedback line can be used instead.
- realtime feedback configuration panel.