 This topic has 7 replies, 4 voices, and was last updated 5 years, 6 months ago by ramdharma.

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24. February 2016 at 9:56 #4135xingtongParticipant
Hi,all
When I run the same LTE_sim_main_luancher_*.m with different trace_version(v1 & v2),
I found the wideband_SINR value of the UE are quite different at same TTI.(PS:SNR_avg_preequal values are same)
v1: the wideband_SINR value ranges from 0dB ~ 20dB
calculation mode:
obj.wideband_SINR = 10*log10(sum(RX_total(:))/(sum(interf_power_all_RB(:))+thermal_noise_watts_per_half_RB*nSC));
v2(runtime precoding): the wideband_SINR value ranges from 20dB ~ 0dB
calculation mode:
obj.wideband_SINR = 10*log10(sum(reshape(RX_total_half_RB_layers_UE/avg_pathloss_linear_0/avg_shadow_fading_linear_0,1,[])) /…
(sum(reshape(RX_W_half_RB_i_UE./avg_pathloss_lin_i_calc(pathloss_idxs)./avg_pathloss_shadow_i_calc(pathloss_idxs),1,[]))…
+noise_W_half_RB*numel(RX_total_half_RB_layers_UE)));
Why are the values so different?Could you help me understand it?
PS: You can find the above code in +network_elements/UE.mBest regards,
XingTong26. February 2016 at 9:41 #4165Martin TaranetzMemberDear XingTong,
we also experienced this behaviour. As far as I remember, this was a bug with the scale [linear or logarithmic] of the path loss and the shadowing. Please set breakpoints at the calculation of RX_total and interf_power_all_RB in v1, and avg_pathloss_linear_0, avg_shadow_fading_linear_0, avg_pathloss_lin_i_calc, avg_pathloss_shadow_i_calc in v2, and check whether they are in linear or dB scale.
Best regards,
Martin.27. February 2016 at 9:16 #4172xingtongParticipantHi,Dear Martin Taranetz
Thank you for your attention.I did as you told me.I find these variables are in linear scale which seems to be right.But with your kind guidance,I found avg_pathloss_lin_i_calc(pathloss_idxs) in v2 was wrong because pathloss_idxs were all the same.That is to say, different interference suffers the same passloss.Then I paid attention to pathloss_idxs.Its calculation is shown as follows.
——————–before———————–% With this calculation, size(RX_W_half_RB_i_UE,3) is 1 which must be unreasonable. pathloss_idxs = zeros(size(RX_W_half_RB_i_UE)); for i_=1:size(RX_W_half_RB_i_UE,3) pathloss_idxs(:,:, i_ ,<strong>:</strong>) = i_; end
——————–later————————
pathloss_idxs = zeros(size(RX_W_half_RB_i_UE)); for i_=1:size(RX_W_half_RB_i_UE,4) pathloss_idxs(:,:,:,i_) = i_; end
————————————————
With later calculation,the wideband_SINR value of the UE becomes normal.Best regards,
Xing.6. April 2016 at 13:28 #4426ramdharmaParticipantHi, I want to work with BCQI algorithm, where I would like to use Highest CQI is 8, that is instead of that 115, i want to run the values between 18, so, is it possible, if yes, tell me the ways
7. April 2016 at 13:26 #4452Fjolla AdemajMemberDear XingTong,
For calculation of the wideband_SINR in v2 trace there was a bug in the code. The right expression is:
obj.wideband_SINR = 10*log10(sum(reshape(RX_total_half_RB_layers_UE./avg_pathloss_linear_0./avg_shadow_fading_linear_0,1,[])) /…
(sum(reshape(RX_W_half_RB_i_UE./10^(2)./avg_pathloss_lin_i_calc(pathloss_idxs)./avg_pathloss_shadow_i_calc(pathloss_idxs),1,[]))…
+noise_W_half_RB*numel(RX_total_half_RB_layers_UE)));Regarding the pathloss indexing you should use the ‘later’ calculation as:
% Indexing matrix for the pathlosses for wideband SINR calculation
pathloss_idxs = zeros(size(RX_W_half_RB_i_UE));
for i_=1:size(RX_W_half_RB_i_UE,4)
pathloss_idxs(:,:,:,i_, 🙂 = i_;
endNote that the pathloss maps are generated per site and not per sector, this leads to the same pathloss value for three sectors, that is why interfering eNodeB sectors of the same site have the same pathloss.
Best regards,
Fjolla.10. April 2016 at 3:46 #4476xingtongParticipantDear Fjolla Ademaj,
I wonder why RX_W_half_RB_i_UE should divide 10^(2),can you explain it?Best regards,
Xing.10. April 2016 at 7:59 #4477xingtongParticipantDear Fjolla Ademaj,
I wonder why RX_W_half_RB_i_UE should divide 10^(2),can you explain it?Best regards,
Xing.15. April 2016 at 13:07 #4497ramdharmaParticipantHi.. I would like to know how bcqi assigns the RB to the user. What are all the requirements the user should posses?
is enb chooses the received feedback or CQI sent of users. I have confusion with this. So, Kindly help me to get over this.
even in Prop fair also i have the same problem….. 
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