Procedure to add dedicated Bandwidth part (BWP)

Contributed by 5G Testbed IISc

Developers: Abhijith A, Shruthi S

Terminology

Bandwidth part (BWP)

Bandwidth Part (BWP) is a set of contiguous Resource Blocks in the resource grid.

Parameters of a Bandwidth Part are communicated to UE using RRC parameters: BWP-Downlink and BWP-Uplink.

A UE can be configured with a set of 4 BWPs in uplink (UL) and downlink (DL) direction. But only 1 BWP can be active in UL and DL direction at a given time.

Procedure to run multiple dedicated BWPs

A maximum of 4 dedicated BWPs can be configured for a UE.

To configure multiple BWPs, add the following parameters to the gNB configuration file under "servingCellConfigDedicated":

Setup of the Configuration files

    firstActiveDownlinkBWP-Id = 1; #BWP-Id 
    defaultDownlinkBWP-Id = 1; #BWP-Id 
    firstActiveUplinkBWP-Id = 1; #BWP-Id

Each dedicated BWP must have:

    # BWP 1 Configuration 
    bwp-Id_1 = 1; 
    bwp1_locationAndBandwidth = 28908; // RBstart=33,L=106 
    # subcarrierSpacing 
    # 0=kHz15, 1=kHz30, 2=kHz60, 3=kHz120  
    bwp1_subcarrierSpacing = 1;

Find these parameters in this configuration file: "targets/PROJECTS/GENERIC-LTE-EPC/CONF/gnb.band78.tm1.106PRB.usrpn300.SCD.conf"

NOTE:

* For changing bandwidth, 'dl_carrierBandwidth' and 'ul_carrierBandwidth' must be modified according 
  to the bandwidth of the BWP
* Currently only 'firstActiveDownlinkBWP-Id' is used to configure both DL and UL BWPs

Testing gNB and UE in RF simulator

gNB command:

    sudo RFSIMULATOR=server ./nr-softmodem -O ../../../targets/PROJECTS/GENERIC-LTE-EPC/CONF/gnb.band78.tm1.106PRB.usrpn300.SCD.conf --rfsim --phy-test -d

UE command:

    sudo RFSIMULATOR=127.0.0.1 ./nr-uesoftmodem --rfsim --phy-test -d

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