How to keep UEs stable when add femtocells

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  • #7496
    suzy
    Participant

    Dear all,
    I am confused with how to keep the number of users stable when adding femtocells. I am running the LTE_sim_main_launcher_demo_femtocells file to analyse the impact of femtocells distribution on LTE network. However, each time I add femtocells, the total number of UEs would be changed. For example, if there should be 50 UEs assigned to one macrocell and 5 UEs assigned to one Femtocell, when a femtocell is added to one macrocell, the total UEs in this macrocell would become 65, which make the impact of femtocells insignificant. I don’t know what causes it and could you please give me some help? The version I use is v1.8r1375.

    And this is the code:
    `
    LTE_config.compact_results_file = false;
    LTE_config.keep_UEs_still = true;

    % Femto specific
    LTE_config.femtocells_config.spatial_distribution = ‘homogenous density’;
    LTE_config.femtocells_config.macroscopic_pathloss_model = ‘TS36942’;
    LTE_config.femtocells_config.macroscopic_pathloss_model_settings.environment = ‘urban’;

    LTE_config.femtocells_config.mode = ‘CSG’;
    LTE_config.femtocells_config.macroscopic_pathloss_model_settings.wall_loss = 20;
    LTE_config.femtocells_config.macroscopic_pathloss_model_settings.penetration_loss = LTE_config.femtocells_config.macroscopic_pathloss_model_settings.wall_loss; % Desired signal experiences penetration loss

    Thanks for your time and consideration.
    Regards,
    Suzy

    #7522
    FX6300
    Participant

    There are 3 sectors in each site.
    Let’s say 5 MUE in each sector and 2 FC in each sector and 1 FUE in each FC.
    Therefore, you have 3 x 5 = 15 MUEs, 3 x 2 x 1 = 6 FUEs, a total of 21 UEs.

    If you add a new FC, the total number of UEs will definitely increase.
    Let’s say 3 FC in each sector and 1 FUE in each FC.
    3 x 5 = 15 MUEs and 3 x 3 x 1 = 9 FUEs, a total of 24 UEs.

    #7526

    Hi Suzy,

    the default UE creation is “constant UEs per cell” which means that when you add femto cells, you also increase the number of UEs.

    You can change this with the parameter LTE_config.UE_distribution (by setting it to “constant UEs per ROI” for example). You can find the generating functions in +spatial_distributions.

    Best regards,
    Martin

    #7553
    suzy
    Participant

    Dear Martin,

    Thanks for your reply. But I still have difficulty in changing the parameter LTE_config.UE_distribution, I don’t know how to change it to ‘constant UEs per ROI’. I have tried several times, but the parameter I set were always wrong. So could you give me some suggestions? Many thanks.

    Regards,
    Suzy

    #7555
    suzy
    Participant

    Hi,

    I have known how to change the parameter, but when I use ‘constant UEs per ROI’, it exists error and cannot work. So how can I solve it?

    The error shows:
    Reference to non-existent field ‘nUEs’
    Error in LTE_init_generate_users_and_add_schedulers (line 24)
    UE_spatial_distribution =
    spatial_distributions.constantElementsPerRoiSpatialDistribution(networkPathlossMap,
    LTE_config.nUEs);
    Error in LTE_sim_main (line 66)
    [UEs, extra_UE_cache_info] =
    LTE_init_generate_users_and_add_schedulers(LTE_config,sites,eNodeBs,networkPathlossMap,CQI_mapper,BLER_curves,networkClock);
    Error in LTE_sim_main_launcher_demo_femtocells (line 51)
    output_results_file = LTE_sim_main(LTE_config);

    Many thanks for your kindly help.

    Regards,
    Suzy

    #7586

    Hi Suzy,

    since the launcher file for femto cells is not made for using “constant UEs per ROI”, you have to specify the number of UEs manually by assigning LTE_config.nUEs a value that corresponds to the number of users you want to create.

    Best regards,
    Martin

    #7652
    suzy
    Participant

    Hi Martin,
    Many thanks to your reply, and the number of UEs in per ROI is stable now. But I still confused about how to define the number of UEs per Femtocell. I have tried use the parameter “LTE_config.UE_per_femtocell”, but it seems useless. So, is it means if I use ‘constant UEs per ROI’, the number of UEs per femtocell could only be decided by default value?

    Regards,
    Suzy

    #7668

    Hi Suzy,

    Defining number of UEs constant per ROI makes the number of UEs independent of the number of femtocells.

    I suggest you have a look at the functions that place UEs in your scenario. You can find them in the folder +spatial_distributions. You might have to build your own function for for UE generation and include it in LTE_init_generate_users_and_add_schedulers as option for UE_distribution.

    Please let me know if you have any further questions regarding this issue.

    Best regards,
    Martin

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