rng('default'); % Reset the random number generator
simParameters = []; % Clear the simulation parameters
simParameters.NumFramesSim = 200; % 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 simulation parameters
% simParameters.UEDistance and simParameters.PacketPeriodicityUEs are
% array of length equal to NumUEs; and simParameters.PacketSizesUEs,
% properties of simParameters.RLCConfig, and simParameters.LCHConfig
% consists of number of rows equal to numUEs.
simParameters.NumUEs = 4;
% Number of logical channels in each UE. If you change the number of
% logical channels, ensure that the simulation parameters
% simParameters.PacketSizesUEs, properties of simParameters.RLCConfig, and
% simParameters.LCHConfig consists of number of columns equal to
% NumLogicalChannels.
simParameters.NumLogicalChannels = 3;
simParameters.UEDistance = [100; 250; 700; 750]; % Distance of UEs from gNB (in meters)

% Set the application traffic pattern for UEs. For example, the vector
% element value 10 at index 4 represents that for each of the logical
% channels of UE-4, a packet is generated every 10 ms
simParameters.PacketPeriodicityUEs = [30; 20; 30; 10]; % Periodicity at which UEs generate packets in logical channels (in ms)
% The N-by-P matrix represents the size of packet generated by
% the UE in each logical channel, where 'N' represents the number of UEs
% and 'P' represents the number of logical channels. For example, the value
% 1000 at index (4, 1) represents a packet of size 1000 bytes generated by
% UE-4 for logical channel ID 1
simParameters.PacketSizesUEs = [4000 6000 8000;
    500  8000 8000;
    12000 8000 4000;
    1000 8000 4000];

% RLC configuration
% Each property of RLCConfig must be an N-by-P matrix, where 'N' represents the number of UEs
% and 'P' represents the number of logical channels. A matrix element at position
% (i, j) corresponds to property value of a UE with RNTI value 'i' and logical channel ID 'j'.
% Sequence number (SN) field length (in bits) to be used by each UE for their logical channels
simParameters.RLCConfig.SNFieldLength = [6 6 12;
    6 6 12;
    6 12 6;
    6 6 12];
% Reassembly timer to be used by each UE for their logical channels
simParameters.RLCConfig.ReassemblyTimer = [5 10 15;
    5  5 10;
    5  5  5;
    5 10 15];
% Max number of service data units (SDUs) in the Tx buffer of each logical channel (to model Tx buffer overflow)
simParameters.RLCConfig.MaxTxBufferSDUs = [4 3 11;
    3 5 4;
    6 1 3;
    11 6 26];

% Logical channel (LCH) configuration
% Each property of LCHConfig must be an N-by-P matrix, where 'N' represents the number of UEs
% and 'P' represents the number of logical channels. A matrix element at position
% (i, j) corresponds to property value of a UE with RNTI value 'i' and logical channel ID 'j'.
% Mapping between logical channel and logical channel group (LCG) ID
simParameters.LCHConfig.LCGID = [1 3 2;
    1 2 2;
    1 2 3;
    5 1 2];
% Priority of each logical channel
simParameters.LCHConfig.Priority = [1 5 8;
    1 1 6;
    4 10 4;
    10 11 13];
% Prioritized bit rate (PBR) of each logical channel (in kilo bytes per second)
simParameters.LCHConfig.PBR = [8 16 32;
    8 128 32;
    8 16 32;
    8 16 32];
% Bucket size duration (BSD) of each logical channel (in ms)
simParameters.LCHConfig.BSD = [5 10 50;
    5 20 20;
    5 5 5;
    5 10 20];

% Medium access control (MAC) configuration
% Set the scheduler run periodicity in terms of number of slots. Value must be
% less than the number of slots in a 10 ms frame
simParameters.SchedulerPeriodicity = 4;
simParameters.SchedulerStrategy = 'PF'; % Supported scheduling strategies: 'PF', 'RR' and 'BestCQI'
% Moving average weight parameter within the range [0, 1] calculates
% average data rate for a UE. The value is used in the PF scheduling strategy.
% Parameter value closer to 1 implies more weight on the instantaneous
% data rate. Parameter value closer to 0 implies more weight on the past
% data rate
% AverageDataRate = ((1 - MovingAvgDataRateWeight) * PastDataRate) + (MovingAvgDataRateWeight * InstantaneousDataRate)
simParameters.MovingAvgDataRateWeight = 0.5;
simParameters.BSRPeriodicity = 5; % In ms
simParameters.EnableHARQ = true; % Flag to enable or disable HARQ. If disabled, there are no retransmissions
simParameters.NumHARQ = 16; % Number of HARQ processes in each UE
% 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 in a slot for a PUSCH transmission (limit is
% applicable for new PUSCH assignments and not for the retransmissions)
simParameters.RBAllocationLimitUL = 15;

% PHY layer and channel configuration
% RB count for 5 MHz band with 15 kHz subcarrier spacing (SCS). The complete
% UL bandwidth is assumed to be allotted for PUSCH
simParameters.NumRBs = 25;
simParameters.SCS = 15; % kHz
simParameters.ULBandwidth = 5e6; % Hz
simParameters.ULCarrierFreq = 2.515e9; % Hz
% Set the RBG size configuration to 1 (configuration-1 RBG table) or 2
% (configuration-2 RBG table) as defined in 3GPP TS 38.214 Section
% 5.1.2.2.1
simParameters.RBGSizeConfig = 1;

% 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: RBCQI = RBCQI +/- CQIDelta
simParameters.ChannelUpdatePeriodicity = 0.5; % In sec
simParameters.CQIDelta = 1;
% 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 10 as the
% distance falls within the [501, 800] meters range, as per the mapping. Set
% the distance in increasing order and the achievable CQI value in decreasing
% order
simParameters.CQIvsDistance = [
    200  15;
    500  12;
    800  10;
    1000  8;
    1200  7];

% Logging and visualization configuration
% Flag to enable or disable run time 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.
simParameters.RBVisualization = true;

% The output metrics plots are updated NumMetricsSteps times during
% simulation
simParameters.NumMetricsSteps = 20;

% MAT-files used for post simulation visualization
simParameters.ParametersLogFile = 'simParameters'; % For logging the simulation parameters
simParameters.SimulationLogFile = 'simulationLogs'; % For logging the simulation logs

hNRULSchedulingValidateConfig(simParameters); % Validate the simulation configuration

simParameters.NCellID = 1; % Physical cell ID
simParameters.DLCarrierFreq = 2.635e9; % Hz
simParameters.DLBandwidth = 10e6; % Hz
simParameters.GNBPosition = [0 0 0]; % Position of gNB in (x,y,z) coordinates
% Slot duration for the selected SCS and number of slots in a 10 ms frame
slotDuration = 1/(simParameters.SCS/15); % Slot duration in ms
numSlotsFrame = 10/slotDuration; % Number of slots in 10 ms frame
numSlotsSim = simParameters.NumFramesSim * numSlotsFrame; % Number of slots in the simulation

% Packet periodicities of UEs in terms of number of slots
appPeriodicityUEsSlots = simParameters.PacketPeriodicityUEs ./ slotDuration;

% Maximum RLC SDU length (in bytes)
simParameters.maxRLCSDULength = 9000;

% RLC entity direction. Value 0 represents downlink only, 1
% represents UL only and 2 represents both UL and downlink
% directions. Setting entity direction to have only UL
simParameters.RLCConfig.EntityDir = ones(simParameters.NumUEs, simParameters.NumLogicalChannels);

% Logical channel id (logical channel ID of data radio bearers starts from 4) 
simParameters.LCHConfig.LCID = ones(simParameters.NumUEs, simParameters.NumLogicalChannels) .* (4:4+simParameters.NumLogicalChannels-1);

% Construct information for RLC logger
lchInfo = repmat(struct('LCID',[],'EntityDir',[]), [simParameters.NumUEs 1]);
for idx = 1:simParameters.NumUEs
    lchInfo(idx).LCID = simParameters.LCHConfig.LCID(idx, :);
    lchInfo(idx).EntityDir = simParameters.RLCConfig.EntityDir(idx, :);
end

% Find maximum achievable CQI value for 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 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
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);
end

% 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

simParameters.Position = simParameters.GNBPosition;
gNB = hNRGNB(simParameters); % Create 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); % Create 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);
    simParameters.InitialChannelQualityDL = simParameters.InitialChannelQualityUL;
    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

    % Setup logical channels
    for lcIdx = 1:simParameters.NumLogicalChannels
        % Create RLC channel configuration structure
        rlcChannelConfigStruct.EntityType = simParameters.RLCConfig.EntityDir(ueIdx, lcIdx);
        rlcChannelConfigStruct.LogicalChannelID = simParameters.LCHConfig.LCID(ueIdx, lcIdx);
        rlcChannelConfigStruct.SeqNumFieldLength = simParameters.RLCConfig.SNFieldLength(ueIdx, lcIdx);
        rlcChannelConfigStruct.MaxTxBufferSDUs = simParameters.RLCConfig.MaxTxBufferSDUs(ueIdx, lcIdx);
        rlcChannelConfigStruct.ReassemblyTimer = simParameters.RLCConfig.ReassemblyTimer(ueIdx, lcIdx);
        rlcChannelConfigStruct.EntityType = simParameters.RLCConfig.EntityDir(ueIdx, lcIdx);
        rlcChannelConfigStruct.LCGID = simParameters.LCHConfig.LCGID(ueIdx, lcIdx);
        rlcChannelConfigStruct.Priority = simParameters.LCHConfig.Priority(ueIdx, lcIdx);
        rlcChannelConfigStruct.PBR = simParameters.LCHConfig.PBR(ueIdx, lcIdx);
        rlcChannelConfigStruct.BSD = simParameters.LCHConfig.BSD(ueIdx, lcIdx);
        
        % 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 UE nodes. Application data
        % is pumped to RLC layer as per the installed traffic pattern
        packetSize = simParameters.PacketSizesUEs(ueIdx, lcIdx);
        % Calculate the data rate (in kbps) of On-Off traffic pattern using
        % packet size (in bytes) and packet interval (in ms)
        dataRate = ceil(1000/simParameters.PacketPeriodicityUEs(ueIdx)) * packetSize * 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 packetSize > simParameters.maxRLCSDULength
            packetSize = 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
        app = networkTrafficOnOff('PacketSize', packetSize, 'GeneratePacket', true, ...
            'OnTime', simParameters.NumFramesSim/100, 'OffTime', 0, 'DataRate', dataRate);
        UEs{ueIdx}.addApplication(ueIdx, simParameters.LCHConfig.LCID(ueIdx, lcIdx), app);
    end
end

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

% To store the following UE metrics for each slot: throughput bytes
% transmitted, goodput bytes transmitted, and pending buffer amount bytes.
% The number of goodput bytes is calculated by excluding the retransmissions from the total
% transmissions
UESlotMetrics = zeros(simParameters.NumUEs, 3);

% To store the RLC statistics for each slot
ueRLCStats = cell(simParameters.NumUEs, 1);
gNBRLCStats = cell(simParameters.NumUEs, 1);

% To store current UL CQI values on the RBs for different UEs
uplinkChannelQuality = zeros(simParameters.NumUEs, simParameters.NumRBs);

% To store last received NDI values for UL HARQ processes
HARQProcessStatus = zeros(simParameters.NumUEs, simParameters.NumHARQ);

% Create an object for MAC scheduling information visualization and logging (UL direction is represented as 1)
simSchedulingLogger = hNRSchedulingLogger(simParameters, 1);

% Create an object for RLC visualization and logging (UL direction is represented as 1)
simRLCLogger = hNRRLCLogger(simParameters, lchInfo, 1);

symbolNum = 0;
% Run processing loop
for slotNum = 1:numSlotsSim
    
    % Run MAC and PHY layers of gNB
    run(gNB.MACEntity);
    run(gNB.PhyEntity);
    
    % Run MAC and PHY layers of UEs
    for ueIdx = 1:simParameters.NumUEs
        % Read the last received NDI flags for HARQ processes for
        % logging (Reading it before it gets overwritten by run function of MAC)
        HARQProcessStatus(ueIdx, :) = getLastNDIFlagHarq(UEs{ueIdx}.MACEntity, 1); % 1 for UL
        run(UEs{ueIdx}.MACEntity); 
        run(UEs{ueIdx}.PhyEntity);
    end
    
    % RLC logging
    for ueIdx = 1:simParameters.NumUEs % For all UEs
        % Get RLC statistics
        ueRLCStats{ueIdx} = getRLCStatistics(UEs{ueIdx}, ueIdx);
        gNBRLCStats{ueIdx} = getRLCStatistics(gNB, ueIdx);
    end
    logRLCStats(simRLCLogger, ueRLCStats, gNBRLCStats); % Update RLC statistics logs
    
    % MAC logging
    % Read UL assignments done by gNB MAC scheduler at current time.
    % Resource assignments returned by a scheduler is empty, if UL
    % scheduler was not scheduled to run at the current time or no
    % resources got scheduled
    resourceAssignmentsUL = getCurrentSchedulingAssignments(gNB.MACEntity);
    for ueIdx = 1:simParameters.NumUEs
        % Read the UL channel quality at gNB for each of the UEs for logging
        uplinkChannelQuality(ueIdx,:) = getChannelQuality(gNB, 1, ueIdx); % 1 for UL
        % Read throughput and goodput bytes transmitted for this UE in the
        % current TTI for logging
        [UESlotMetrics(ueIdx, 1), UESlotMetrics(ueIdx, 2)] = getTTIBytes(UEs{ueIdx});
        UESlotMetrics(ueIdx, 3) = getBufferStatus(UEs{ueIdx}); % Read pending buffer (in bytes) on UE
    end
    % Update scheduling logs based on the current slot run of UEs and gNB.
    % Logs are updated in each slot, RB grid visualizations are updated
    % every frame, and metrics plots are updated every metricsStepSize
    % slots
    logScheduling(simSchedulingLogger, symbolNum + 1, resourceAssignmentsUL, UESlotMetrics, uplinkChannelQuality, HARQProcessStatus, 1);
    
    % Visualization
    % If RB Visualization flag is set, update the RB assignment grid at the
    % last slot of each frame
    if simParameters.RBVisualization && mod(slotNum, numSlotsFrame) == 0
        plotRBGrids(simSchedulingLogger);
    end
    % If CQI Visualization flag is set, update the CQI grid at the last
    % slot of each frame
    if simParameters.CQIVisualization && mod(slotNum, numSlotsFrame) == 0
        plotCQIRBGrids(simSchedulingLogger);
    end
    % Plot MAC scheduling performance, RLC throughput metrics at every metricsStepSize slots
    if mod(slotNum, simParameters.MetricsStepSize) == 0
        plotMetrics(simSchedulingLogger);
        plotMetrics(simRLCLogger);
    end
    
    tickGranularity = 14; % Number of symbols in a slot
    % 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
    
    % Symbol number in the simulation
    symbolNum = symbolNum + tickGranularity;
end

% Read the logs and save them in MAT-files
simulationLogs = cell(1, 1);
simulationLogs{1} = struct('ULTimeStepLogs',[], 'SchedulingAssignmentLogs',[] ,'RLCLogs',[]);
[~, simulationLogs{1}.ULTimeStepLogs] = getSchedulingLogs(simSchedulingLogger); % UL time step scheduling logs
simulationLogs{1}.SchedulingAssignmentLogs = getGrantLogs(simSchedulingLogger); % Scheduling assignments log
simulationLogs{1}.RLCLogs = getRLCLogs(simRLCLogger); % RLC statistics logs
save(simParameters.SimulationLogFile, 'simulationLogs'); % Save simulation logs in a MAT-file
save(simParameters.ParametersLogFile, 'simParameters'); % Save simulation parameters in a MAT-file