ul_start.m

MATLAB仿真WCDMA

function [size, crc, chCode, CD, CC, control] = ul_start(d_Code, c_Code, c_type, Kindex, nFrames,tx_ch)
%
%
% FUNCTION:     ul_start      
% AUTHOR:       Maarit Melvasalo
% DATE:         April 21, 1999
%
% DESC:         This fuction set values for downlink transport channels
%               defined in Simulink library:  utra_lib 
%               These values have been obtained from ETSI UTRA 
%               for ITU-R RTT.  
%
% NOTE:         Parameter value may be changed, but be carefully!
%               Do not change the calcutions.   
%
% HISTORY:      June 17,1999 Maarit Melvasalo
%                   Comments added
%
% *******************************************************************
%
% INPUTS:
%
%  d_Code  = [code_length, index] = 
%            spreading factor and index for data channel 
%  c_Code  = [code_length, index] = 
%            spreading factor and index for control channel 
%  c_type  = mode indicating the channel coding scheme
%       1  = Convolutional coding with   
%       3  = Turbo coding (NOT YET)
%  K_index = Coding ratio (input values: (1,2)
%  nFrames = number of frames in each block interleaver
%  tx_ch   = transport channel type
%
%         1 = Dedicated physical channel (both data and control channels)
%         2 = Physical random acces channel (both data and control channels) 
%
% OUTPUTS: 
%
% size = [N = input_block_size bits_in_frame nFrames N_offset nSlot chips_in_slot]
%             input_block_size= number of bits in each input block (calculated)
%             bits_in_frame   = number of coded bits in one frame (calculated)
%                               Note that this does not include contorl bits
%             nFrames         = number of frames in each block (given by user) 
%             N_offset        = offset required to obtain correct blocksize (calculated)
%                               after channel coding (and before interleaving)
%             nSlot           = number of slots in frame (set by user)
%             chips_in_slot   = number of slots in frame (constant for given bit bandwidth)
%
% crc = [nCRC poly] 
%             nCRC  = number of CRC bits  (set by user) different for different 
%                     physical channels
%             poly  = generating polynomial for CRC (set by user)
%
% chCode = [c_type K tail poly]
%             c_type  = channel type (given in function call = set by user) 
%             K       = Coding gain  (given in function call = set by user) 
%             tail    = Coding tail length  (set by user)
%             poly    = Generating polynomials for channel coding (set by user)
%
% CD = spreading code for data channel
%
% CC = spreading code for control channel
%
% control = [nPilot TPC TFI] 
%             nPilot  = number of Pilot bits (given by user) 
%             TPC     = number of Power control bits (given by user) 
%             TFI     = number of Transport Format Indicator bits (given by user)  
% 
%


% ***************************************************************
%
% Common parameters to all Up and Downlink transport channels
%
% ***************************************************************

      R = 4096000;        % chips /s
      nSlot = 16;         % Number of slots per frame same as 
                          % wcdma_config.h = SLOTS_IN_FRAME
      tFrame = 1/100;     % 10 ms = frame time 
                          % Simulink s-functions use TD_FRAME = 1 
                          % defined in wcdma_config.h
      chips_in_slot = R/nSlot * tFrame; 
                           % Number of chips in each slot (constant) 

% ***************************************************************
%
%        CRC Basic settings  (for data channel)
%
% *************************************************************** 

    nCRC = 16 ;                     % Number of CRC bits;  
    crc_q = '1021';                  % ARIB  in decimal presentation  4129
    CRCQ = base2dec(crc_q,16);      % same in decimal representation
    crc = [nCRC CRCQ]; 

% ***************************************************************
% ***************************************************************
%
%       CONVOLUTIONAL CODING PARAMETERS (for data channel)
%
% *************************************************************** 

if (c_type == 1)

%*****************************************
% CODING RATIO
% Kindex == 1 -> K = 2; 
% Kindex == 2 -> K = 3;

     K = Kindex + 1 ;  tail = 8;  

% The Generator polynomials for convolutional coding and decoding
% see UTRA specification chapter 5.2.1.1.1 

     Base = 8;  % indicates the base in which the numbers are given

     if (K == 3)
         p1_o = '557';  % desimal: 367;
         p2_o = '663';  % desimal: 435;
	 p3_o = '711';  % desimal: 457; 
     else 
         p1_o = '561';  % desimal: 367;
	 p2_o = '753';  % desimal: 435;
	 p3_o = '0';    % desimal: N/A; 
     end;


     poly = [base2dec(p1_o,Base) base2dec(p2_o,Base) base2dec(p3_o,Base)];


     chCode = [c_type  K tail poly];

%*****************************************
%
%      SPREADING CODE FOR DATA CHANNEL 
%
%*****************************************     

     % if the spreading code has not been assigned

     if ( length(d_Code)  < 3)
     
           % set the code index for a inital value 
           index = d_Code(1) / 2 ;

           % If the code index has been defined by the function call
           % check that is 
           if ((length(d_Code) == 2) & ((index <= d_Code) & (index >0) ))  
               index = d_Code(2);     end;

	   CD = get_ovsf_code(d_Code(1),index);                 
     end; 


     if ( length(d_Code) > 2) % if the spreading code has already been assigned 
           CD = d_Code;
           d_Code = length(CD);
     end;


% *************************************************************** 
%
%      NUMBER OF BITS IN DATA CHANNEL 
%      BLOCK, FRAME AND SLOT ETC 
%           
%              DO NOT CHANGE!!!!!!!!
%
% *************************************************************** 

     total_bits = R/d_Code(1);
     coded_bits_frame = total_bits * tFrame; 
     data_bits_in_slot = coded_bits_frame / nSlot ; 


     % Size of the inputblock to CRC must be * 8 

     N_total = nFrames * coded_bits_frame - tail  ;
     N_tmp = floor(N_total / K);
     if( nCRC > 0)
         N_tmp = 8 * floor(N_tmp / 8)  ;
     end;
     N = N_tmp - nCRC ;
     N_offset = N_total - N_tmp*K;

     size =[N coded_bits_frame nFrames N_offset nSlot chips_in_slot];


% ***************************************************************
%
%      CONTROL CHANNEL DEFINITONS (for control channel)
%
% *************************************************************** 

%*****************************************
%
%      SPREADING CODE FOR CONTROL CHANNEL 
%
%*****************************************     

     % if the spreading code has not been assigned

     if ( length(c_Code)  < 3)
     
           % set the code index for a inital value 
           index = c_Code(1) / 2 + 1;

           % If the code index has been defined by the function call
           % check that is 
           if ((length(c_Code) == 2) & ((index <= c_Code) & (index >0) ))  
               index = c_Code(2);     end;

	   CC = get_ovsf_code(c_Code(1),index);                 
     end; 



     if ( length(c_Code) > 2) % if the spreading code has already been assigned 
           CC = c_Code;
           c_Code = length(CC);
     end;

% ***************************************************************
%
%      NUMBER OF CONTROL BITS
%
% *************************************************************** 

     TPC = 3;    TFI = 2;

     bits_in_slot = R/c_Code(1)* tFrame /nSlot; % =number of bits in slot
     nPilot = bits_in_slot - TPC -TFI;

     control = [nPilot TPC TFI];

     return;
end;  
% ***************************************************************
%       END of CONVOLUTIONAL CODING
% ***************************************************************     


% ***************************************************************
%
%       TURBO CODING PARAMETERS
%
%       NOT IMPLEMENTED YET
%
% *************************************************************** 

if (c_type > 1)
    disp('Only the convolutiona channel coding is implemented currently');
size = 0;
crc =0;
CC = 0;
CD = 0;
chCode = 0;
control =0;

    return;
end;