phyhd.m

802.15 dsss 物理协议层方针代码

function phy_header = phyhd(frame_data,seed,band,datarate,modulation)
%Use the paramaters to create a 24bits PHY header contain important
%informations
% frame_data - the data should be transfered, i.e. MAC data
% seed - seed identifier
% band - high or low
% datarate - transfer data rate
% modulation - type of modulation i.e. 4BOK or BPSK
phy_header=zeros(1,24);%PHY HEADER is 3 octets
seed_id=[0 0;0 1;1 0;1 1];%seed identifier, 4 seeds to generate scrambler.
fec_type=[0 0 0; 0 0 1;0 1 0;0 1 1;1 0 0;1 0 1;1 1 0; 1 1 1];
% FEC type, 3 bits: 0-no FEC;
                     % 1-k=6, rate 1/2
                     % 2-k=6, rate 3/4
                     % 3-k=4, rate 1/2
                     % 4-k=4, rate 3/4
                     % 5,6-for furture use
                     % 7-I define here(not appear in standard rate 1)
intx_type=[0,1];%Interleaver Type:0-convolutional bit interleaver
                                 %1-for further use
code_length=[ 0 0 0; 0 0 1;0 1 0;0 1 1;1 0 0;1 0 1;1 1 0; 1 1 1];
%Payload code length,3 bits: 0 - length 24
                           % 1 - length 12
                           % 2 - length 6
                           % 3 - length 4
                           % 4 - length 3
                           % 5 - length 2
                           % 6 - length 1
                           % 7 - for furture use
mod_type=[0 0; 0 1;1 0;1 1];
% Modulation Type: 0 - BPSK
                 % 1 - 4-BOK natural coding
                 % 2 - 4-BOK Gray coding
                 % 3 - for furture use
frame_length = zeros(1,13);
templ=length(frame_data);
for i=1:13
    frame_length(i)=floor(templ/2^(13-i));
    templ=templ-frame_length(i)*2^(13-i);
end
switch modulation
    case 'BPSK'
        modtype=1;
        switch band
            case 'low'
                switch datarate
                    case 28
                        fec=fec_type(1,:);
                        codelength=code_length(1,:);
                    case 55
                        fec=fec_type(1,:);
                        codelength=code_length(2,:);
                    case 110
                        fec=fec_type(1,:);
                        codelength=code_length(3,:);
                    case 220
                        fec=fec_type(1,:);
                        codelength=code_length(5,:);
                    case 500
                        fec=fec_type(2,:);
                        codelength=code_length(6,:);
                    case 660
                        fec=fec_type(8,:);
                        codelength=code_length(6,:);
                    case 1000
                        fec=fec_type(2,:);
                        codelength=code_length(7,:);
                    case 1320
                        fec=fec_type(8,:);
                        codelength=code_length(7,:);
                end
            case 'high'
                switch datarate
                    case 28
                        error('No 28Mbps in High band!');
                        return;
                    case 55
                        fec=fec_type(1,:);
                        codelength=code_length(1,:);
                    case 110
                        fec=fec_type(1,:);
                        codelength=code_length(2,:);
                    case 220
                        fec=fec_type(1,:);
                        codelength=code_length(3,:);
                    case 500
                        fec=fec_type(2,:);
                        codelength=code_length(4,:);
                    case 660
                        fec=fec_type(8,:);
                        codelength=code_length(4,:);
                    case 1000
                        fec=fec_type(2,:);
                        codelength=code_length(6,:);
                    case 1320
                        fec=fec_type(8,:);
                        codelength=code_length(6,:);
                end
        end
    case '4BOK'
        modtype=2;
        switch band
            case 'low'
                switch datarate
                    case 110
                        fec=fec_type(1,:);
                        codelength=code_length(2,:);

                    case 220
                        fec=fec_type(1,:);
                        codelength=code_length(3,:);
                    case 500
                        fec=fec_type(2,:);
                        codelength=code_length(4,:);
                    case 660
                        fec=fec_type(8,:);
                        codelength=code_length(4,:);

                    case 1000
                        fec=fec_type(2,:);
                        codelength=code_length(6,:);
                    case 1320
                        fec=fec_type(8,:);
                        codelength=code_length(6,:);
                end
            case 'high'
                switch datarate
                    case 220
                        fec=fec_type(1,:);
                        codelength=code_length(2,:);
                    case 660
                        fec=fec_type(2,:);
                        codelength=code_length(3,:);
                    case 1000
                        fec=fec_type(2,:);
                        codelength=code_length(4,:);
                    case 1320
                        fec=fec_type(8,:);
                        codelength=code_length(4,:);
                end
        end
end
                
% create the header     
switch seed
    case 00
        si=1;
    case 01
        si=2;
    case 10
        si=3;
    case 11
        si=4;
end
phy_header(1:2)=seed_id(si,:);
phy_header(3:5)=fec;
phy_header(6)=intx_type(1);
phy_header(7:9)=codelength;
phy_header(10:11)=mod_type(modtype,:);
phy_header(12:24)=frame_length;