function pathloss_dB = PathLoss_Hotspot_Floors(frequency_GHz,distance_m, number_floors, environment)
% Give the pathloss between UE and BS located in the same building and
% differents floors.
% Propagation model extracted from IUT-R P.1238-8 (July 2015)
%
%%%%%%%%%%%%%%%%%%%%%
% ----------------------
%   INPUT parameters  
% ----------------------
% *frequency_GHz: emission frequency (GHz)
% *distance_m: distance between transmitter Tx et receiver Rx (m) 
%              Right if distance_m > 1m
% *number_floors: Number of floors between BS and UE
% *environment: Explain what is the environment. 
%               Possible values: 'Residential', 'Office', 'Commercial', 'Factory', 'Corridor'
%               PLEASE RESPECT THE SYNTAX
% 
% ----------------------
%   OUTPUT parameters  
% ----------------------
% *pathloss_dB
%
% ----------------------
%   FUNCTIONS used  
% ----------------------
% *interpolation.m
%
% ----------------------
%   COMMENTS 
% ----------------------
% *For the 'Residential' environment, it can be separated into two environments: "House" and "Apartment".
%  In this case, Power_loss_coefficient and floor_penetration may changed.
%  Not implemented yet.
% 
% *To calculate power_loss_coefficient (N), we used linear interpolation or
%  extrapolation if the given frequency is not in the tables.
%  Extrapolation function not implemented yet.
%
% * A lot of particularities are described in the IUT-R P.1238-8 original document.
%   Refer to it, if you have some uncertainties.
% 
% 
%
%
%%%%%%%%%%%%%%%%%%%%%
 frequency_MHz = frequency_GHz*10^3;
CST_EPSILON=0.01;
% BLOC 1: DETERMINE POWER LOSS COEFFICIENT = N
% Create Power Loss Coefficients (N) table from IUT-R P.1238-8.
%            Input: frequency_GHz, environment
%            Output: power_loss_N
% Structures in Matlab are used to create 2 tables (frequencyGHz and N) for each environment. 

switch(environment)
    case 'Residential'
       power_loss_coefficient.Residential.frequencyGHz=[1.9 2.4 5.2];
       power_loss_coefficient.Residential.N=[28 28 30];
       
          for i=1:1:length(power_loss_coefficient.Residential.frequencyGHz)
            if frequency_GHz==power_loss_coefficient.Residential.frequencyGHz(i)
                power_loss_N = power_loss_coefficient.Residential.N(i);
            else if frequency_GHz < 5.2 && frequency_GHz > 1.9 %use Linear Interpolation
                    power_loss_N = interpolation(frequency_GHz, power_loss_coefficient.Residential.frequencyGHz);
                 else
                    % use Linear Extrapolation, not implemented yet...
                    disp('ERROR_Residential: Linear Extrapolation not implemented yet')
                    pathloss_dB=0;
                    return
                end
            end
          end
       
    case 'Office'
        power_loss_coefficient.Office.frequencyGHz=[0.9 1.25 1.9 2.1 2.4 3.5 2.625 4 5.2 5.8 60 70];
        power_loss_coefficient.Office.N=[33 32 30 25.5 30 27 44 28 31 24 22 22];
        
         for i=1:1:length(power_loss_coefficient.Office.frequencyGHz)
            if frequency_GHz==power_loss_coefficient.Office.frequencyGHz(i)
                power_loss_N = power_loss_coefficient.Office.N(i);
            else if frequency_GHz < 70 && frequency_GHz > 0.9 %use Linear Interpolation
                    power_loss_N = interpolation(frequency_GHz, power_loss_coefficient.Office.frequencyGHz);
                 else
                    % use Linear Extrapolation, not implemented yet...
                    disp('ERROR_Office: Linear Extrapolation not implemented yet')
                    pathloss_dB=0;
                    return
                end
            end
          end
        
    case 'Commercial'
        power_loss_coefficient.Commercial.frequencyGHz=[0.9 1.25 1.9 2.1 4 27.6 17];
        power_loss_coefficient.Commercial.N=[20 22 22 20 22 27.6 17];
        
         for i=1:1:length(power_loss_coefficient.Commercial.frequencyGHz)
            if frequency_GHz==power_loss_coefficient.Commercial.frequencyGHz(i)
                power_loss_N = power_loss_coefficient.Commercial.N(i);
            else if frequency_GHz < 60 && frequency_GHz > 0.9 %use Linear Interpolation
                    power_loss_N = interpolation(frequency_GHz, power_loss_coefficient.Commercial.frequencyGHz);
                 else
                    % use Linear Extrapolation, not implemented yet...
                    disp('ERROR_Commercial: Linear Extrapolation not implemented yet')
                    pathloss_dB=0;
                    return
                end
            end
          end
        
    case 'Factory'
        power_loss_coefficient.Factory.frequencyGHz=[2.1 2.625];
        power_loss_coefficient.Factory.N=[21.1 33];
        
         for i=1:1:length(power_loss_coefficient.Factory.frequencyGHz)
            if frequency_GHz==power_loss_coefficient.Factory.frequencyGHz(i)
                power_loss_N = power_loss_coefficient.Factory.N(i);
            else if frequency_GHz < 2.625 && frequency_GHz > 2.1 %use Linear Interpolation
                    power_loss_N = interpolation(frequency_GHz, power_loss_coefficient.Factory.frequencyGHz);
                 else
                    % use Linear Extrapolation, not implemented yet...
                    disp('ERROR_Factory: Linear Extrapolation not implemented yet')
                    pathloss_dB=0;
                    return
                end
            end
          end
        
    case 'Corridor'
        power_loss_coefficient.Corridor.frequencyGHz=[2.1 60];
        power_loss_coefficient.Corridor.N=[17 16];
        
        if LOS_probability(distance_m,'InH')>0.5
         for i=1:1:length(power_loss_coefficient.Corridor.frequencyGHz)
            if frequency_GHz==power_loss_coefficient.Corridor.frequencyGHz(i)
                power_loss_N = power_loss_coefficient.Corridor.N(i);
            else if frequency_GHz < 60 && frequency_GHz > 2.1 %use Linear Interpolation
                    power_loss_N = interpolation(frequency_GHz, power_loss_coefficient.Corridor.frequencyGHz);
                 else
                    % use Linear Extrapolation, not implemented yet...
                    disp('ERROR_Corridor: Linear Extrapolation not implemented yet')
                    pathloss_dB=0;
                    return
                end
            end
         end
        else
            disp('For Corridor environment, BS and UE must be in LOS.')
            disp('Probability to be in LOS < 0.5.')
            pathloss_dB=0;
            return
        end
        
end


% BLOC 2: DETERMINE FLOOR PENETRATION LOSS FACTOR = Lf = floor_penetration
% Create Floor penetration loss factor from IUT-R P.1238-8.
%            Input: frequency_GHz, number_floors
%            Output: floor_penetration

switch(environment)
    case 'Residential'
        if frequency_GHz <2 && frequency_GHz>1.8
            floor_penetration = 4*number_floors;
        elseif frequency_GHz >= 2.4 && frequency_GHz <= 2.6
            floor_penetration = 10;
            % We can use Office results for (0.9, 3.5, 5.8)GHz frequencies
        elseif abs(frequency_GHz-0.9)<CST_EPSILON
            floor_penetration = 9.*(number_floors == 1)+ 19.*(number_floors == 2) + 24.*(number_floors == 3);
        elseif abs(frequency_GHz-3.5)<CST_EPSILON
            floor_penetration = 18.*(number_floors == 1)+ 26.*(number_floors == 2);
        elseif abs(frequency_GHz-5.8)<CST_EPSILON
            floor_penetration = 22.*(number_floors == 1)+ 28.*(number_floors == 2);
        else
            disp('Calcul of floor_penetration:')
            disp('No reference in IUT-R P.1238-8 for this frequency')
            disp('By default: floor_penetration = 0')
            floor_penetration = 0;
            return
        end
    case 'Office'
        if abs(frequency_GHz-0.9)<CST_EPSILON
            floor_penetration = 9.*(number_floors == 1)+ 19.*(number_floors == 2) + 24.*(number_floors == 3);
        elseif frequency_GHz > 1.8 && frequency_GHz < 2
            floor_penetration = 15 + 4*(number_floors-1);
        elseif frequency_GHz >= 2.4 && frequency_GHz <= 2.6
            floor_penetration = 14;  
        elseif abs(frequency_GHz-3.5)<CST_EPSILON
            floor_penetration = 18.*(number_floors == 1)+ 26.*(number_floors == 2);
        elseif abs(frequency_GHz-5.2)<CST_EPSILON
            floor_penetration = 16.*(number_floors == 1);
        elseif abs(frequency_GHz-5.8)<CST_EPSILON
            floor_penetration = 22.*(number_floors == 1)+ 28.*(number_floors == 2);
        else
            disp('Calcul of floor_penetration:')
            disp('No reference in IUT-R P.1238-8 for this frequency')
            disp('By default: floor_penetration = 0')
            floor_penetration = 0;
            return
        end
    case 'Commercial'
        if frequency_GHz > 1.8 && frequency_GHz < 2                        
            floor_penetration = 6 +3*(number_floors-1);
        else
            disp('Calcul of floor_penetration:')
            disp('No reference in IUT-R P.1238-8 for this frequency')
            disp('By default: floor_penetration = 0')
            floor_penetration = 0;
            return
        end
end

% Basic model equation
pathloss_dB = 20*log10(frequency_MHz)-28 + power_loss_N*log10(distance_m) + floor_penetration;

end