About Walking model – SLvsLL

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    a) To understand the “SLvsLL” walking model, any reference on “SLvsLL” walking model as what it is and how it is derived will be helpful. can this be shared please?

    b) When SLvsLL model is enabled, the new position is same to all UEs irrespective of the UE’s original position.
    The new position is derived from “obj.distances = 10.^(PL/20)*299792458/(4*pi*2e9);” which is static value defined as part of the walking model object.

    In the straight walk model, the new position is determined w.r.to the current position.
    Is the returning of same value n SLvsLL an error? or am i missing something?

    c) When should we choose SLvsLL model?

    Requesting help with suitable replies.

    Best Regards
    Manikantan Srinivasan
    CSE Department
    IIT-Madras, Chennai, India.


    Dear Mani,

    The walking model SLvsLL defines a UE walking in a straight line. It was created with the purpose of comparing our link-level with the system-level simulator, and using very specific scenarios, as you can see from the values there.

    With the SLvsLL waling model, after defining the distances vector for the positions we want to move the UE along this stright line, it generates the new position by counting the number of elements of the distance vector. It doesn’t return the same value.

    If you are getting the same position, then the UE is not moving, please check the parameter LTE_config.keep_UEs_still = true/false; (true: UE doesn’t move).



    Dear Fjolla


    Thank you for the clarification on SLvsLL (System level vs Link level) it helps.

    I will recheck the values, ensuring the parameter LTE_config.keep_UEs_still is set to true.

    May be i was bit unclear, For a given UE, at different instances, it gives a different value, however when for a bunch of UEs, i.e. (20 UEs per eNB) are associated with the SLvsLL model all UEs were assigned the same value (new position). I will recheck it again and share my observations.

    Can you kindly confirm if the straight walking model is the applicable model to use for UE mobility (when more than one UE is enabled at an eNB) related study, and SLvsLL is a special scenario not to be used in a generic way.

    Thanks again
    Best regards

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