rng('default'); % Reset the random number generator
simParameters = []; % Clear simParameters variable
simParameters.NumFramesSim = 100; % Simulation time in terms of number of 10 ms frames

% Number of UEs in the simulation. UEs are assumed to have sequential radio
% network temporary identifiers (RNTIs) from 1 to NumUEs. If you change the
% number of UEs, ensure that the following simulation parameters are array
% of length equal to NumUEs: simParameters.UEDistance,
% simParameters.ULPacketPeriodicityUEs, simParameters.ULPacketSizesUEs,
% simParameters.DLPacketPeriodicityUEs, simParameters.DLPacketSizesUEs
simParameters.NumUEs = 4;
simParameters.UEDistance = [100; 150; 300; 400]; % Distance of UEs from gNB (in meters)

% Set the value of scheduling type to 0 (slot-based scheduling) or 1
% (symbol-based scheduling). If value is not set, the default value is 0
simParameters.SchedulingType = 1;

% Set the time-domain assignment in terms of symbol duration. If number of
% symbols (DL or UL) are not enough for this granularity then a smaller
% valid granularity is chosen. Applicable only for symbol-based scheduling.
% For slot-based scheduling, biggest possible granularity in a slot is
% chosen
simParameters.TTIGranularity = 4;

% Define the TDD DL-UL pattern. The reference subcarrier spacing used for
% calculating slot duration for the pattern is assumed to be same as actual
% subcarrier spacing used for transmission as defined by simParameters.SCS.
% Keep only the symbols intended for guard period during DLULPeriodicity
% with type (DL or UL) unspecified
simParameters.DLULPeriodicity = 5; % Duration of the DL-UL pattern in ms
simParameters.NumDLSlots = 2; % Number of consecutive full DL slots at the beginning of each DL-UL pattern
simParameters.NumDLSyms = 8; % Number of consecutive DL symbols in the beginning of the slot following the last full DL slot
simParameters.NumULSyms = 4; % Number of consecutive UL symbols in the end of the slot preceding the first full UL slot
simParameters.NumULSlots = 2; % Number of consecutive full UL slots at the end of each DL-UL pattern

% Mapping between distance from gNB (first column in meters) and maximum
% achievable UL CQI value (second column). For example, if a UE is 700
% meters away from the gNB, it can achieve a maximum CQI value of 8 as the
% distance falls within the [501, 1000] meters range, as per the mapping.
% Set the distance in increasing order and the maximum achievable CQI value
% in decreasing order
simParameters.CQIvsDistance = [
    200  15;
    300  12;
    500  10;
    1000  8;
    1200  7];

% Set the periodic UL and DL application traffic pattern for UEs
simParameters.ULPacketPeriodicityUEs = [20; 30; 20; 30]; % Periodicity (in ms) at which the UL packets are generated by UEs
simParameters.ULPacketSizesUEs = [4000; 6000; 5500; 4000]; % Size of the UL packets (in bytes) generated by UEs
simParameters.DLPacketPeriodicityUEs = [20; 15; 15; 20]; % Periodicity (in ms) at which the DL packets are generated for UEs at gNB
simParameters.DLPacketSizesUEs = [6000; 5000; 10000; 8000]; % Size of the DL packets generated (in bytes) for UEs at gNB

% Medium access control (MAC) configuration
simParameters.SchedulerStrategy = 'PF'; % Supported scheduling strategies: 'PF', 'RR' and 'BestCQI'
% PUSCH preparation time. gNB ensures that PUSCH assignment is received at
% UEs PUSCHPrepTime ahead of the transmission time
simParameters.PUSCHPrepTime = 200; % In microseconds
% Maximum RBs allotted to a UE for PUSCH and PDSCH transmissions (limit is
% applicable for new transmission assignments and not for the retransmissions)
simParameters.RBAllocationLimitUL = 15; % For PUSCH
simParameters.RBAllocationLimitDL = 15; % For PDSCH
simParameters.BSRPeriodicity = 1; % Buffer status report transmission periodicity (in ms)

simParameters.DMRSTypeAPosition = 2;
% PUSCH DM-RS configuration
simParameters.PUSCHDMRSAdditionalPosTypeB = 0;
simParameters.PUSCHDMRSAdditionalPosTypeA = 0;
simParameters.PUSCHDMRSConfigurationType = 1;
% PDSCH DM-RS configuration
simParameters.PDSCHDMRSAdditionalPosTypeB = 0;
simParameters.PDSCHDMRSAdditionalPosTypeA = 0;
simParameters.PDSCHDMRSConfigurationType = 1;

% PHY layer and channel configuration
% RB count for 5 MHz band with 15 kHz subcarrier spacing (SCS). The complete
% bandwidth is assumed to be allotted for PUSCH or PDSCH
simParameters.NumRBs = 25;
simParameters.SCS = 15; % kHz
simParameters.DLBandwidth = 5e6; % Hz
simParameters.ULBandwidth = 5e6; % Hz
simParameters.DLCarrierFreq = 2.595e9; % Hz
simParameters.ULCarrierFreq = 2.595e9; % Hz

% Configure parameters to update channel conditions for the UEs. Channel
% quality is periodically improved or deteriorated by CQIDelta every
% channelUpdatePeriodicity seconds for all RBs of a UE. Whether channel
% conditions for a particular UE improve or deteriorate is randomly
% determined: RB_CQI = RB_CQI +/- CQIDelta
simParameters.ChannelUpdatePeriodicity = 0.2; % In sec
simParameters.CQIDelta = 1;

% Logging and visualization configuration
% Flag to enable or disable runtime CQI visualization
simParameters.CQIVisualization = true;
% Flag to enable or disable run time visualization of RB assignment. If enabled,
% then for slot-based scheduling it updates every frame (10 ms) to show RB
% allocation to the UEs for different slots of the last frame. For
% symbol-based scheduling, it updates every slot to show RB allocation to
% the UEs over different symbols of the last slot
simParameters.RBVisualization = false;
% The output metrics plots are updated periodically NumMetricsSteps times within the
% simulation duration
simParameters.NumMetricsSteps = 20;
% MAT-files to write the logs into. They are used for post simulation analysis and visualization
simParameters.ParametersLogFile = 'simParameters'; % For logging the simulation parameters
simParameters.SimulationLogFile = 'simulationLogs'; % For logging the simulation logs

hNRSchedulingTDDValidateConfig(simParameters); % Validate the simulation configuration

simParameters.DuplexMode = 1; % TDD (example specific constant)
if simParameters.SchedulingType % Symbol-based scheduling
    simParameters.PUSCHMappingType = 'B';
    simParameters.PDSCHMappingType = 'B';
else % Slot-based scheduling
    simParameters.PUSCHMappingType = 'A';
    simParameters.PDSCHMappingType = 'A';
end
simParameters.NCellID = 1; % Physical cell ID
simParameters.GNBPosition = [0 0 0]; % Position of gNB in (x,y,z) coordinates
numLogicalChannels = 1; % Only 1 logical channel is assumed in each UE (Example specific constant)
slotDuration = 1/(simParameters.SCS/15); % Slot duration in ms
numSlotsFrame = 10/slotDuration; % Number of slots in 10 ms frame
numSlotsSim = simParameters.NumFramesSim * numSlotsFrame; % Simulation time in units of slot duration
numSymbolsSim = numSlotsSim * 14; % Simulation time in units of symbol duration
% Interval at which metrics visualization updates in terms of number of
% slots. Make sure that MetricsStepSize is an integer
simParameters.MetricsStepSize = ceil(numSlotsSim / simParameters.NumMetricsSteps);
if mod(numSlotsSim, simParameters.NumMetricsSteps) ~= 0
    % Update the NumMetricsSteps parameter if numSlotsSim is not
    % completely divisible by it
    simParameters.NumMetricsSteps = floor(numSlotsSim / simParameters.MetricsStepSize);
end

% Logical channel id (logical channel ID of data radio bearers starts from 4) 
simParameters.LCHConfig.LCID = 4;

% RLC entity direction. Value 0 represents DL only, 1
% represents UL only and 2 represents both UL and DL
% directions. Setting entity direction to have both UL and DL
simParameters.RLCConfig.EntityDir = 2;
% Construct information for RLC logger
lchInfo = repmat(struct('RNTI',[],'LCID',[],'EntityDir',[]), [simParameters.NumUEs 1]);
for idx = 1:simParameters.NumUEs
    lchInfo(idx).RNTI = idx;
    lchInfo(idx).LCID = simParameters.LCHConfig.LCID;
    lchInfo(idx).EntityDir = simParameters.RLCConfig.EntityDir;
end

% Create RLC channel configuration structure
rlcChannelConfigStruct.LCGID = 1; % Mapping between logical channel and logical channel group ID
rlcChannelConfigStruct.Priority = 1; % Priority of each logical channel
rlcChannelConfigStruct.PBR = 8; % Prioritized bitrate (PBR), in kilobytes per second, of each logical channel
rlcChannelConfigStruct.BSD = 10; % Bucket size duration (BSD), in ms, of each logical channel
rlcChannelConfigStruct.EntityType = simParameters.RLCConfig.EntityDir;
rlcChannelConfigStruct.LogicalChannelID = simParameters.LCHConfig.LCID;

% Maximum RLC SDU length (in bytes) as per 3GPP TS 38.323
simParameters.maxRLCSDULength = 9000;

% Calculate maximum achievable CQI value for the UEs based on their distance
% from the gNB
maxUECQIs = zeros(simParameters.NumUEs, 1); % To store the maximum achievable CQI value for UEs
for ueIdx = 1:simParameters.NumUEs
    % Based on the distance of the UE from gNB, find matching row in CQIvsDistance mapping
    matchingRowIdx = find(simParameters.CQIvsDistance(:, 1) > simParameters.UEDistance(ueIdx));
    if isempty(matchingRowIdx)
        maxUECQIs(ueIdx) = simParameters.CQIvsDistance(end, 2);
    else
        maxUECQIs(ueIdx) = simParameters.CQIvsDistance(matchingRowIdx(1), 2);
    end
end

% Define initial UL and DL channel quality as an N-by-P matrix,
% where 'N' is the number of UEs and 'P' is the number of RBs in the carrier
% bandwidth. The initial value of CQI for each RB, for each UE, is given
% randomly and is limited by the maximum achievable CQI value corresponding
% to the distance of the UE from gNB
simParameters.InitialChannelQualityUL = zeros(simParameters.NumUEs, simParameters.NumRBs); % To store current UL CQI values on the RBs for different UEs
simParameters.InitialChannelQualityDL = zeros(simParameters.NumUEs, simParameters.NumRBs); % To store current DL CQI values on the RBs for different UEs
for ueIdx = 1:simParameters.NumUEs
    % Assign random CQI values for the RBs, limited by the maximum achievable CQI value
    simParameters.InitialChannelQualityUL(ueIdx, :) = randi([1 maxUECQIs(ueIdx)], 1, simParameters.NumRBs);
    % Initially, DL and UL CQI values are assumed to be equal
    simParameters.InitialChannelQualityDL(ueIdx, :) = simParameters.InitialChannelQualityUL(ueIdx, :);
end

% Update periodicity of RB assignment visualization in terms of number of slots
if ~isfield(simParameters, 'SchedulingType') || simParameters.SchedulingType == 0 % If no scheduling type is specified or slot-based scheduling is specified
    rbAssignmentPlotPeriodicity = numSlotsFrame; % Update every frame (10 ms)
else % Symbol-based scheduling
    rbAssignmentPlotPeriodicity = 1; % Update every slot
end

simParameters.Position = simParameters.GNBPosition;
gNB = hNRGNB(simParameters); % Create the gNB node
% Create and add scheduler
switch(simParameters.SchedulerStrategy)
    case 'RR' % Round robin scheduler
        scheduler = hNRSchedulerRoundRobin(simParameters);
    case 'PF' % Proportional fair scheduler
        scheduler = hNRSchedulerProportionalFair(simParameters);
    case 'BestCQI' % Best CQI scheduler
        scheduler = hNRSchedulerBestCQI(simParameters);
end
addScheduler(gNB, scheduler); % Add scheduler to gNB

gNB.PhyEntity = hNRGNBPassThroughPhy(simParameters); % Add passthrough PHY
configurePhy(gNB, simParameters);
setPhyInterface(gNB); % Set the interface to PHY layer

% Create the set of UE nodes
UEs = cell(simParameters.NumUEs, 1);
for ueIdx = 1:simParameters.NumUEs
    simParameters.Position = [simParameters.UEDistance(ueIdx) 0 0]; % Position of UE
    UEs{ueIdx} = hNRUE(simParameters, ueIdx);
    UEs{ueIdx}.PhyEntity = hNRUEPassThroughPhy(simParameters, ueIdx); % Add passthrough PHY
    configurePhy(UEs{ueIdx}, simParameters);
    setPhyInterface(UEs{ueIdx}); % Set the interface to PHY layer

    % Initialize the UL CQI values at gNB
    updateChannelQuality(gNB, simParameters.InitialChannelQualityUL(ueIdx, :), 1, ueIdx); % 1 for UL
    % Initialize the DL CQI values at gNB and UE. The DL CQI values
    % help gNB in scheduling, and UE in packet error probability estimation
    updateChannelQuality(gNB, simParameters.InitialChannelQualityDL(ueIdx, :), 0, ueIdx); % 0 for DL
    updateChannelQuality(UEs{ueIdx}, simParameters.InitialChannelQualityDL(ueIdx, :));

    % Setup logical channel at gNB for the UE
    configureLogicalChannel(gNB, ueIdx, rlcChannelConfigStruct);
    % Setup logical channel at UE
    configureLogicalChannel(UEs{ueIdx}, ueIdx, rlcChannelConfigStruct);

    % Add data traffic pattern generators to gNB and UE nodes
    ulPacketSize = simParameters.ULPacketSizesUEs(ueIdx);
    % Calculate the data rate (in kbps) of On-Off traffic pattern using
    % packet size (in bytes) and packet interval (in ms)
    ulDataRate = ceil(1000/simParameters.ULPacketPeriodicityUEs(ueIdx)) * ulPacketSize * 8e-3;
    % Limit the size of the generated application packet to the maximum RLC
    % SDU size. The maximum supported RLC SDU size is 9000 bytes
    if ulPacketSize > simParameters.maxRLCSDULength
        ulPacketSize = simParameters.maxRLCSDULength;
    end
    % Create an object for On-Off network traffic pattern and add it to the
    % specified UE. This object generates the uplink (UL) data traffic on the UE
    ulApp = networkTrafficOnOff('PacketSize', ulPacketSize, 'GeneratePacket', true, ...
        'OnTime', simParameters.NumFramesSim/100, 'OffTime', 0, 'DataRate', ulDataRate);
    UEs{ueIdx}.addApplication(ueIdx, simParameters.LCHConfig.LCID, ulApp);

    dlPacketSize = simParameters.DLPacketSizesUEs(ueIdx);
    dlDataRate = ceil(1000/simParameters.DLPacketPeriodicityUEs(ueIdx)) * dlPacketSize * 8e-3;
    if dlPacketSize > simParameters.maxRLCSDULength
        dlPacketSize = simParameters.maxRLCSDULength;
    end
    % Create an object for On-Off network traffic pattern for the specified
    % UE and add it to the gNB. This object generates the downlink (DL) data
    % traffic on the gNB for the UE
    dlApp = networkTrafficOnOff('PacketSize', dlPacketSize, 'GeneratePacket', true, ...
        'OnTime', simParameters.NumFramesSim/100, 'OffTime', 0, 'DataRate', dlDataRate);
    gNB.addApplication(ueIdx, simParameters.LCHConfig.LCID, dlApp);

end

% Setup the UL and DL packet distribution mechanism
simParameters.MaxReceivers = simParameters.NumUEs;
% Create DL packet distribution object
dlPacketDistributionObj = hNRPacketDistribution(simParameters, 0); % 0 for DL
% Create UL packet distribution object
ulPacketDistributionObj = hNRPacketDistribution(simParameters, 1); % 1 for UL
hNRSetUpPacketDistribution(simParameters, gNB, UEs, dlPacketDistributionObj, ulPacketDistributionObj);

% Create an object for MAC (UL & DL) scheduling information visualization and logging
simSchedulingLogger = hNRSchedulingLogger(simParameters);
% Create an object for RLC layer metrics logging
simRLCLogger = hNRRLCLogger(simParameters, lchInfo);

% Create visualization object for RLC and MAC metrics
visualizer = hNRMetricsVisualizer(simParameters, 'RLCLogger', simRLCLogger, 'LCHInfo', lchInfo, 'MACLogger', simSchedulingLogger);

slotNum = 0;
tickGranularity = 1;
% Execute all the symbols in the simulation
for symbolNum = 1 : tickGranularity : numSymbolsSim
    symbolType = currentSymbolType(gNB); % Get current symbol type: DL/UL/Guard
    if mod(symbolNum - 1, 14) == 0
        slotNum = slotNum + 1;
    end
    
    % Run MAC and PHY layers of gNB
    run(gNB);
    
    % Run MAC and PHY layers of UEs
    for ueIdx = 1:simParameters.NumUEs
        run(UEs{ueIdx});
    end
    
    % RLC logging (only at slot boundary)
    if mod(symbolNum - 1, 14) == 0 %
        logCellRLCStats(simRLCLogger, gNB, UEs);
    end
    
    % MAC logging
    logCellSchedulingStats(simSchedulingLogger, symbolNum, gNB, UEs);
    
    % Visualization
    % Check slot boundary
    if symbolNum > 1 && ((simParameters.SchedulingType == 1 && mod(symbolNum, 14) == 0) || (simParameters.SchedulingType == 0 && mod(symbolNum-1, 14) == 0))
        % RB assignment visualization (if enabled)
        if simParameters.RBVisualization
            if mod(slotNum, rbAssignmentPlotPeriodicity) == 0
                % Plot at slot boundary, if the update periodicity is reached
                plotRBGrids(simSchedulingLogger);
            end
        end
        % CQI grid visualization (if enabled)
        if simParameters.CQIVisualization
            if mod(slotNum, numSlotsFrame) == 0 % Plot at frame boundary
                plotCQIRBGrids(simSchedulingLogger);
            end
        end
        % Plot scheduler metrics and RLC metrics visualization at slot
        % boundary, if the update periodicity is reached
        if mod(slotNum, simParameters.MetricsStepSize) == 0
            plotMetrics(visualizer, slotNum);
        end
    end
    
    % Advance timer ticks for gNB and UEs by 'tickGranularity' symbols
    advanceTimer(gNB, tickGranularity);
    for ueIdx = 1:simParameters.NumUEs % For all UEs
        advanceTimer(UEs{ueIdx}, tickGranularity);
    end
end

% Read the logs and write them to MAT-files
% Get the logs
simulationLogs = cell(1,1);
logInfo = struct('TimeStepLogs',[], 'SchedulingAssignmentLogs',[] ,'RLCLogs',[]);
[logInfo.TimeStepLogs] = getSchedulingLogs(simSchedulingLogger);
logInfo.SchedulingAssignmentLogs = getGrantLogs(simSchedulingLogger); % Scheduling assignments log
logInfo.RLCLogs = getRLCLogs(simRLCLogger); % RLC statistics logs
simulationLogs{1} = logInfo;

save(simParameters.SimulationLogFile, 'simulationLogs'); % Save simulation logs in a MAT-file
save(simParameters.ParametersLogFile, 'simParameters'); % Save simulation parameters in a MAT-file