防碰撞算法matlab,如何用matlab对RFID中的防碰撞算法（aloha和或二进制数）仿真
global STANDBY TRANSMIT COLLISION PERMIT
global Srate Plen Ttime Dtime
global Mnum Mplen Mstime Mstate
global Tint Rint
global Spnum Splen Tplen Wtime
STANDBY = 0; % definition of the fixed number
TRANSMIT = 1;
COLLISION = 2;
PERMIT = 3;
% definition of the protocol
protocol = { 'paloha' ... % Pure ALOHA : pno = 1
'saloha' ... % Slotted ALOHA : pno = 2
'npcsma' ... % np-CSMA : pno = 3
'snpisma' ... % Slotted np-ISMA : pno = 4
};
% definition of communication channel 通信信道的定义
brate = 512e3; % bit rate 比特率
Srate = 256e3; % symbol rate 符号速率
Plen = 128; % length of a packet 包长度
Dtime = 0.01; % normalized propagation delay 归一化传播延迟
alfa = 3; % decline fixed number of propagation loss 固定数量的减少传输损耗
sigma = 6; % standard deviation of shadowing [dB] 阴影的标准差
% definition of the access point 接入点的定义
r = 100; % service area radius [m] 服务区半径
bxy = [0, 0, 5]; % position of the access point (x,y,z)[m] 接入点的位置
tcn = 10; % capture ratio [dB] 捕获率
% definition of the access terminals 接入终端
Mnum = 5; % number of the access terminal
mcn = 30; % C/N at the access point when transmitted from area edge
% simulation condition 模拟条件
pno = 3; % protocol number
capture = 0; % capture effect 0:nothing 1:consider 捕获效应
spend = 10000; % number of packets that simulation is finished
outfile = 'test.dat'; % result output file name
Ttime = Plen / Srate; % transmission time of one packet
mpow = 10^(mcn/10) * sqrt(r^2+bxy(3)^2)^alfa; % true value of C/N
fid = fopen(outfile,'w');
fprintf(fid,'Protocol = %d\n',pno);
fprintf(fid,'Capture = %d\n',capture);
fprintf(fid,'Normalize_delay_time = %f\n',Dtime);
fprintf(fid,'Bit_rate (bps)= %d\n',brate);
fprintf(fid,'Symbol_rate (sps)= %d\n',Srate);
fprintf(fid,'Length_of_Packet (sbl)= %d\n',Plen);
fprintf(fid,'Number_of_mobile_station= %d\n',Mnum);
fprintf(fid,'Transmission_power (C/N)= %f\n',mcn);
fprintf(fid,'Capture_ratio (dB)= %f\n',tcn);
fprintf(fid,'Number_of_Packet = %d\n',spend);
fprintf('\n********* Simulation Start *********\n\n');
if capture == 0
fprintf(' %s without capture effect\n\n',char(protocol(pno)));
else
fprintf(' %s with capture effect\n\n',char(protocol(pno)));
end
mxy = position(r,Mnum,0); % positioning of the access terminals 'r'服务区半径'Mnum'接入终端数
randn('state',sum(100*clock)); % resetting of the random table 重置随机表???????
mrnd = randn(1,Mnum); % decision of the shadowing ????
for G=[0.1:0.1:1,1.2:0.2:2] % offered traffic
if G >= Mnum
break
end
Tint = -Ttime / log(1-G/Mnum); % expectation value of the packet generation interval
Rint = Tint; % expectation value of the packet resending interval
Spnum = 0;
Splen = 0;
Tplen = 0;
Wtime = 0;
now_time = feval(char(protocol(pno)),-1); % initialize of the access terminals
while 1
next_time = feval(char(protocol(pno)),now_time);
if Spnum >= spend
break
end
idx = find(Mstate==TRANSMIT | Mstate==COLLISION);
if capture == 0 % without capture effect
if length(idx) > 1
Mstate(idx) = COLLISION; % collision occurs
end
else % with capture effect
if length(idx) > 1
dxy = distance(bxy,mxy(idx,:),1); % calculation of the distance
pow = mpow * dxy.^-alfa .* 10.^(sigma/10*mrnd(idx)); % calculation of received power
[maxp no] = max(pow);
if Mstate(idx(no)) == TRANSMIT
if length(idx) == 1
cn = 10 * log10(maxp);
else
cn = 10 * log10(maxp/(sum(pow)-maxp+1));
end
Mstate(idx) = COLLISION;
if cn >= tcn % received power larger than capture ratio
Mstate(idx(no)) = TRANSMIT; % transmitting success
end
else
Mstate(idx) = COLLISION;
end
end
end
now_time = next_time; % time is advanced until the next state change time
end
traffic = Tplen / Srate / now_time; % calculation of the traffic
ts = theorys(pno,traffic,Dtime); % calculation of the theory value of the throughput
fprintf(fid,'%f\t%f\t%f\t%f\t%f\t%f\t%f\n',G,now_time ...
,Splen/Srate,Tplen/Srate,Wtime,Tint,Rint);
fprintf('G=%f\tS=%f\tTS=%f\n',traffic,Splen/Srate/now_time,ts);
end
fprintf('\n********** Simulation End **********\n\n');
fclose(fid);
graph(outfile);