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Synchronisation issues with the No-OS LTE transmission

Question asked by on Jun 23, 2016
Latest reply on Jun 27, 2016 by larsc


you know us working on a project for LTE transmission and reception using Zynq boards and your FMCOMMS5 boards. Let me explain the procedure that we followed so far, for which we had communications previously:

a) We tested the No-OS example of yours, where the sine wave is transmitted. The Tx/Rx was considered successful although a matter of phase synchronization was evident.

b) We implemented a No-OS example using an LTE waveform, where the received LTE waveform was confirmed with a lower dB value depending on the gain at the receiver. However, synchronisation issues can not be figured out in this case.

To this end, we need to measure the BER of the LTE baseband. We have implemented  our own LTE baseband DL (in C code) that we can run on the processor of the Zynq board, that has already been tested (on a PC) in terms of BER for different values of SNR, and it is correct.

This implementation is deployed with a loopback communication in the FMCOMMS5, where we already tested the a) and b) examples mentioned above.

The issue is that the measured BER is totally wrong, almost 0.5, and it seems that we have synchronisation issues or something else that is related to the fact that the Rx Frame is not compared with the right element (i.e. the first with first one, and so on) of the Tx Frame. This might be a synchronisation issue that was obvious for the sine wave transmission, where the sinusoid signal at I and Q exposed phase shift with the original ones.

Unless, it is something else that we can not identify.

Please advice.