low RI with 2x2CLSM

Viewing 6 posts - 1 through 6 (of 6 total)
  • Author
    Posts
  • #7711
    Naser
    Participant

    Dear Fjolla,

    When I run 1×1 system, it show av. cell throughput of let say (22)Mbps,with rank 1=100%.

    then when i run 2x2CLSM,it almsot double the TP(44)Mbps, but with rank1=99.95%, and only 0.05% for ranks 2 !

    could you please clarify why rank2 has low percentage while the TP is still doubled(which normal in 2×2).

    regards,
    Naser

    #7751

    Dear Naser,

    could you please specify, which launcher file you are using? Otherwise we can’t reproduce your results.

    Best regards,
    Martin

    #7849
    Naser
    Participant

    Dear Martin,
    I ve used ” LTE_sim_main_launcher_demo_RRH”, RRH is disabled though.

    My question is that when we use 2×2, we see double the throughput (TP) compared with 1×1, which is normal.
    but should we expect to see high value on Rank 2 ?

    Thanks,
    Naser

    #8090

    Dear Nasser,

    about the rank, this is correct. Only for very good channel conditions, there will be an improvement when using two streams in a 2×2 setup.

    Why you see the increase in throughput comes from a higher SINR when using the transmit and receive antennas for diversity.

    You can also check this by looking at the average CQI. It will be significantly higher for a 2×2 setup than for a 1×1 setup.

    Best regards,
    Martin

    #8091
    Naser
    Participant

    Dear Martin,

    Thanks for your email, the improvement is non negotiable, as 2×2 MIMO has higher SINR (channel condition).
    My question is: why in MIMO, still we has very low rank 2 (% 0.01), and dominant rank 1 of (% 99.9)?
    when we expect to have higher rank 2 in RI matrix (UE trace) ?

    #8094

    Hi Naser,

    as I said: you can use a higher CQI, since you have an SINR improvement due to diversity. Using your 2×2 antennas for spatial multiplexing is only the right choice for very good channel conditions. Therefore it is only chosen in a few cases.

    In essence: Even when not transmitting over 2 streams, you improve your througput through higher SINR and therefore higher CQI.

    You can also check the improvement in throughput and average CQI when using a 2×1 or 1×2 antenna setup. The RI is constant one, but the SINR is improved.

    Best regards,
    Martin

Viewing 6 posts - 1 through 6 (of 6 total)
  • You must be logged in to reply to this topic.