Beamforming for broadcast signals in 5G lena

[Shadab]

Dear users,

I have a general question about the implementation of the broadcast signals in 5G lena. For example, according to the standards, I believe we can have 4-8 wide beams for SSBs in FR1 whereas upto 64 beams for in FR2. Is this how SSBs are currently generated in 5G lena? If yes, are the SSB beams are generated following some standard patterns?

Any insight will be appreciated. Thank you.

Best regards,

Shadab

[Kent Huns]

Hi Shadab,

SSB sweeping is only supported in initial access.

Please see below sources. And the settings are up to you.

helper/nr-helper.cc

void

NrHelper::AttachToMaxRsrpGnb(const Ptr<NetDevice>& ueDevice, const NetDeviceContainer& enbDevices)

{

    auto nrInitAssoc = m_initialAttachmentFactory.Create<NrInitialAssociation>();

    ueDevice->GetObject<NrUeNetDevice>()->SetInitAssoc(nrInitAssoc);

    nrInitAssoc->SetUeDevice(ueDevice);

    nrInitAssoc->SetGnbDevices(enbDevices);

    nrInitAssoc->SetColBeamAngles(m_initialParams.colAngles);

    nrInitAssoc->SetRowBeamAngles(m_initialParams.rowAngles);

    nrInitAssoc->FindAssociatedGnb();

    auto maxRsrpEnbDevice = nrInitAssoc->GetAssociatedGnb();

    AttachToGnb(ueDevice, maxRsrpEnbDevice);

}

model/nr-initial-association.h

model/nr-initial-association.cc

double

NrInitialAssociation::ComputeMaxRsrp(const Ptr<NetDevice>& gnbDevice, LocalSearchParams& lsps)

{

    auto& chParams = lsps.chParams;

    auto& mobility = lsps.mobility;

    auto& antennas = lsps.antennaArrays;

    uint8_t activePanelIndex = GetUeActivePanel();

    antennas.gnbArrayModel = ExtractGnbParameters(gnbDevice, lsps);

    auto gnbTxPower = DynamicCast<NrGnbNetDevice>(gnbDevice)->GetPhy(0)->GetTxPower();

    for (size_t k = 0; k < antennas.ueArrayModel.size(); k++)

    {

        for (size_t j = 0; j < m_rowBeamAngles.size(); j++)

        {

            for (size_t i = 0; i < m_colBeamAngles.size(); i++)

            {

                auto bf =

                    GenBeamforming(m_rowBeamAngles[j], m_colBeamAngles[i], antennas.gnbArrayModel);

                antennas.gnbArrayModel->SetBeamformingVector(bf);

                txParams->psd = Copy<SpectrumValue>(fakePsd);

                auto rxParam = chParams.spectrumPropModel->DoCalcRxPowerSpectralDensity(

                    txParams,

                    mobility.gnbMobility,

                    mobility.ueMobility,

                    antennas.gnbArrayModel,

                    antennas.ueArrayModel[k]);

                auto eng = gnbTxPower * ComputeRxPsd(rxParam);

                if (eng > lsps.maxPsdFound)

                {

                    lsps.maxPsdFound = eng;

                    bfAngles = {m_rowBeamAngles[j], m_colBeamAngles[i]};

                    activePanelIndex =

                        k; // active panel has to be update to K as better beam has found

                }

            }

        }

    }

    auto attenuation =

        chParams.pathLossModel->CalcRxPower(0, mobility.gnbMobility, mobility.ueMobility);

    m_bestBfVectors.push_back(bfAngles);

    return pow(10.0, attenuation / 10.0) * lsps.maxPsdFound;

}

[Mahboob, Shadab]

Hi Kent,

Thanks a lot for your reply. I will check them

Best regards,

Shadab

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From: 5g-len...@googlegroups.com <5g-len...@googlegroups.com> on behalf of Kent Huns <kent.sa...@gmail.com>
Sent: Wednesday, December 3, 2025 7:32:59 AM
To: 5G-LENA-users <5g-len...@googlegroups.com>
Subject: Re: Beamforming for broadcast signals in 5G lena

 

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