WCDMA matlab代码

function [size, crc, chCode, C, control] = dl_start(nCode, c_type, Kindex, nFrames,tx_ch) % % % FUNCTION: dl_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 % Copyright disclaimer: % This software was developed at the National Institute of Standards % and Technology by employees of the Federal Government in the course % of their official duties. Pursuant to title 17 Section 105 of the % United States Code this software is not subject to copyright % protection and is in the public domain. % % We would appreciate acknowledgement if the software is used. % % ******************************************************************* % % INPUTS: % % nCode =[code_length, index ] = % spreading factor and index (NOTE index is not required!!) % If the code has been pre set i.e nCode = C, nothing is done % 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 transport channel % 2 = Primarly common control physical cahnnel (NO CRC) % 3 = Secondary common control physical channel (FACH or PCH) % % OUTPUTS: % % size = [N = input_block_size bits_in_frame nFrames N_offset nSlot] % input_block_size= number of bits in each input block (calculated) % bits_in_frame = number of coded bits in frame (calculated) % Note that this does not include contorl bits % nFrames = number of frames in each block (calculated) % 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) % % C = spreading code % spreading code depends on given parameters (calculated / given by user) % % 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 Downlink transport channels % % *************************************************************** R = 4096000; % chips rate 1/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) % *************************************************************** % If only only one argument is given at the function call % only the basic parameters are returned to the user if(nargin == 1) size = [nSlot,chips_in_slot]; crc =0; C = 0; chCode = 0; control =0; return end; % *************************************************************** % % CRC Basic settings % % *************************************************************** 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 % % *************************************************************** 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)]; % *************************************************************** % % NUMBER OF CONTROL BITS % % *************************************************************** nPilot = 8; TPC = 3; TFI = 2; % If not Dedicated transport channel update the following parameters: if(tx_ch == 3) TPC = 0; TFI = 0; % Secondary common control end; if (tx_ch == 2) TPC = 0; TFI = 0; nCRC = 0; % Primary common control crc = [nCRC CRCQ]; if (nCode(1) < 256) disp('Only Spreading ratio 256 allowed for Primary common control channel'); nCode(1)=256; end; end; % *************************************************************** % Update return values chCode = [c_type K tail poly]; control = [nPilot TPC TFI]; % *************************************************************** % % SPREADING CODE % % *************************************************************** % if the spreading code has not been assigned if ( length(nCode) < 3) % set the code index for a inital value index = nCode(1) / 2 ; % If the code index has been defined by the use % in thefunction call check that is valid index if ((length(nCode) == 2) & ((index <= nCode) & (index >0) )) index = nCode(2); end; % Call a matalb mex function which returns the code C = get_ovsf_code(nCode(1),index); end; if ( length(nCode) > 2) % if the spreading code has already been assigned C = nCode; nCode = length(C); end; % *************************************************************** % % NUMBER OF BITS IN BLOCK, FRAME AND SLOT ETC % % DO NOT CHANGE!!!!!!!! % % *************************************************************** total_bits = R/nCode(1) * 2 ; bits_in_slot = total_bits * tFrame / nSlot ; coded_bits_frame = (bits_in_slot - nPilot -TPC - TFI) * nSlot ; % NOTE: % 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