Forum Replies Created
23. January 2018 at 17:48 #9253
Hope you fine and well.
Please I have the following question:
What is the number of antenna system [N (no. of antenna at BS) x M (no. of antenna at UE)] in the LTE-A ? for the following releases:
1) Release 10
2) Release 11
3) Release 12
4) Release 13
5) Release 14
6) Release 15
7) Release 16
and what is the real system which is already used in the current 4G networks ?
Seerwan7. May 2017 at 18:34 #8034
Dear Stefan, in my question (1) above regarding the big size of H, I meant how the estimator e.g. MMSE estimator can estimate matrix like this size?.Does the estimator work on all antennas at a time or on each antenna? or how ?, please could you clarify that for me?. Many thanks.
Seerwan6. May 2017 at 23:32 #8030
Dear Stefan, Hope you are fine. I highly appreciate your help and to all the staff members of “Vienna simulator” and also special thanks for Prof. Markus Rupp.
Dear Stefan I have the following questions please:
1) Just I confused a bit about something regarding the size of channel matrix H, I took another example for instance 8 antennas at the base station and 4 antennas at the UE for BW 1.4 then I have calculated the size of H ( 72 x 14 x 8 x 4= 32256). So just I wonder how the simulator manage that big size of H(32256) in estimating the channel information ? does the simulator takes the matrix H for each antenna with its UEs separately and estimate matrix H or how can manage that?
2) The former example was for 1UE what is the change in the size of H if I use 2 or 3 UEs? does the size of H still same?
3) Can I consider the simulator works as a Macro cell or which cell type the simulator supports?
Seerwan1. May 2017 at 12:10 #7958
I highly appreciate your valuable feedback.
Stefan I have question about the mobility speed of the mobile user, why the throughput declines at high speeds?
Seerwan28. March 2017 at 17:30 #7852
Just to add a question… why 14 ??
I read that for normal CP it would be 7, and for extended 6, so, why 14.
Seerwan27. March 2017 at 14:01 #7838
Hope you are fine and I highly appreciate your valuable comments.
Stefan regarding the post above “Size of channel matrix H”. I want to see how the size of H in the channel model (Y=HX+n) increases with increasing the number of antennas for both BS and UE and sure with the bandwidth. So based on your comments the size for (4×2) antennas can be calculated as “size: number of subcarriers x number of OFDM symbols x number of receive antennas x number of spatial transmit layers, for example in my 4×2 case this could be 72x14x4x2 for 1.4 MHz of bandwidth”.
So does the size of H is (72x14x4x2= 8064)? does that mean the size of H (8064 x 8064)?
Please Stefan could you clarify more and what is the change when change when use bandwidth 20 MHz?
Many thanks for you time
Seerwan20. December 2016 at 15:12 #7107
Many thanks for your valuable comments and help. Stefan regarding the diversity in the transmission between the UE and enodeB. just I wonder for instance if there is just 1 antenna at the UE and 8 antennas at the enodeB, so in diversity mode how many antennas of the enodeB will be exploited by the UE. in other words, does the UE which has just 1 antenna receives data from (all the antennas) of the enodeB at a time? or there is like an equation or mathematical relation that the enodeB consider it to know how many streams of the same date can be sent over its antenna ports to this UE (e.g. because the UE has just 1 antennas so the enodeB should use for example 2 or 3 to send data instead of using all antennas?
Seerwan20. December 2016 at 0:21 #7093
May this new year full of health, peace and happiness for you.
Regarding your question above yes it is but the increase of throughput was with each SNR not just with very high SNR?.
I know that the throughput is calculated based on the received bits as you said in the last time. But if have just two streams how can the throughput increases?
Stefan also I wonder why the curve of throughput of cell with increasing the number of antennas at the enodb (at high SNR ) reaches to a saturation value quicker and continue on this value till the end?
Seerwan12. December 2016 at 22:16 #7010
I highly appreciate your help. Stefan please still I am confused from where this increase in TP came if I have just two streams in transmission between sender and receiver, please could you clarify more how the value of throughput increase with increasing the number of antennas at base station while the UE has fix no. of antennas. (note that the mode of transmission that used is mode 4). and where or in which file this happens in the simulator?
Many thanks Stefan.
Seerwan13. November 2016 at 23:13 #6643
I Highly appreciate your support and help.
– Regarding the Q2 above (although your answer is very perfect but please pardon me for my further questions on these points). Just for more clarification, you said that “The feedback values, namely CQI, RI and PMI are then calculated from this (estimated) channel matrix in the scheduler”, this is happen in the base station however, to best of my knowledge, In order to support dynamic adaptation, these three reports (CQI, PMI and RI) should be generated by the mobile terminal UE and then feeding them back to the base stations through the (channel matrix H) to aid with scheduling and link adaptation. I thing just instead of CQI the UE calculate the SINR, so the channel matrix that has been sent by the UE to the base station already include these information. I wonder if I am right or wrong?
– Regarding Q6 above,
The cell throughput = SUM ( all UEs throughput).
UE throughput (i) = B * log(1+SINR(i))
where,B is the bandwidth and the value of SINR is given in the simulator as vector of values (SNR_vec = linspace(0,30,8).
My question is the above equation of UE throughput is same the equation that is used in the simulator to find the UE throughput? and in which line of code is calculated? because I have difficulty to find it in simulationResultsUL.m . Many thanks
Seerwan9. November 2016 at 20:41 #6628
Many thanks for your valuable comments. Stefan Just regarding the Q3 above in reality what is the main source of this delay (in case there is a delay in the system), is it from the complexity of the channel estimator? or from the overhead in computations or from the communication link delay between the UE and eNodeB? or from the large number of pilot samples or from the scheduler? or there is anything else? Thank you very much.
Seerwan17. September 2016 at 21:46 #6145
Thank you for your concern. Could you let me know if it is possible to make all base stations called at a time, not sequentially.
Seerwan7. September 2016 at 0:35 #6072
First of all, I highly appreciate your comments and your valuable feedback. Yes, you can consider like what you have said. In fact, I want to do a study about the Co-relation between the base stations but in case when they are working at the same time (in parallel). Pleasssse Stefan, I want your help in this issue, and from where in the simulator should start to change the sequential to parallel? and which part of code should be modified and how? and how many files should have this modification?
Stefan, I am looking forward to your feedback. Thank you very much for your help and support.
Seerwan5. September 2016 at 14:46 #6040
Thanks for your feedback,
I understand from your reply that the programming was made sequential. however, is it possible to make the processing in parallel?, and how? i.e., all eNodeBs are processed at the same time ? just like the parfor with parallel pool.
Seerwan31. August 2016 at 19:18 #6022
Is the throughput of high SNR e.g (25db) same as the throughput of low SNR e.g.(1db)?
Thank you very much