蜂窝小区同频干扰的Matlab仿真Word文档格式.docx
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DESCRIPTIONOFTHEEXPERIMENTS
1.Writeaprogramtocalculatethesignalinterferenceratio（SIR）intheforwardlink,andrepeatsitbyrandomlychangingthepositionoftheMS.Afteranumberofsimulations,usethesimulatedresultstodrawthehistogramoftheSIR（S=I）.TrytoobtainhistogramswithdifferentpathlossexponentnandclustersizeN.Concludeyourresults.
Theco-channelinterferenceintheforwardlinkcanbecharacterizedinfigure1.AMSwillbeinterferedbytheco-channelbasestation.Inoursimulation,weconsiderthe18co-channelcell,including6cellsinthefirstloopand12cellsinthesecond,nomatterwhattheclustersizeNis.
Figure1forwardlinkco-channelinterference
（1）Firstly,weshouldrandomlychoosethepositionoftheMSinthecell.Sincethecellishexagonwhichishardtohandlewecutandpasteitintoasquare.Aswecanseeinfigure2,thecenterofthecoordinationisthecenterofthecell.ThesquarewechooseisABCD.WethenrandomlychooseapairofxandyasthecoordinateofMS.IfMSlocatesintriangle1wecutandpasteittotriangle3andifitlocatesintriangle2wemoveittotriangle4.
Weassumetherangeofthebasestationis0.1asradiusofclusteris1.FortheMSwholocatedwithinthisarea,wechangeitsdistancetobe0.1asitistooclosetothebasestaion.
Figure2randomlychoosethepositionofMSinacell
Matlabcode:
RandPOS.m
%*******************************************************************
%ThisfunctionistogettherandomlylactionoftheMSwithmtimes.
%zisam*1matrixwithcoodinatevaluex,y
%*******************************************************************function[z]=RandPOS（m）
%********getrandomvalueofx,ywithinasquare*****%x=1.5*rand（m,1）-1;
y=sqrt（3）*rand（m,1）-0.5*sqrt（3）;
%********useforlooptocutthesquareintoahexagon*****%fork=1:
m
ifx（k）>
-1&
&
x（k）<
-0.5&
y（k）>
（1+x（k））*sqrt（3）x（k）=x（k）+1.5;
y（k）=y（k）-sqrt（3）/2;
elseifx（k）>
y（k）<
-（1+x（k））*sqrt（3）x（k）=x（k）+1.5;
y（k）=y（k）+sqrt（3）/2;
end
%********iftheMSistoonearlytothebasestation ******%ifsqrt（x（k）^2+y（k）^2）<
0.1
x（k）=0.1;
y（k）=0;
z=x+j*y;
.
（2）Secondly,weshouldcalculatethecoordinateofco-channelbasestation.AsweknowtheclustersizeNwecancalculatethe（i,j）pairbytheformula𝑁
=𝑖
2+𝑖
*𝑗
+𝑗
2
ClusterN.m
%*********************************************************
%Thisfunctionistofindi&
jcorrespondtoagivenN
%asN=i^2+j^2+ij
%iiandjjistheresultofi,j
%********************************************************function[ii,jj]=ClusterN（N）
%thelargestnumberofiandjissqrt（N）
fora=0:
sqrt（N）
forb=0:
ifa^2+b^2+a*b==Nii=a;
jj=b;
end;
%endifend;
%forjj
（3）TakingN=7asexample,wecancalculatethecoordinatebyreferringtofigure3.AccordingtothevalueofIjpairandanglesinthefigurewecangetthecoordinateofthefirst loop by the formula:
𝑗
×
𝑝
𝑖
+𝑗
𝑝
𝑗
𝑙
𝑜
𝑐
𝑎
𝑡
𝑛
（𝑘
）=3×
（𝑖
𝑒
6
3×
（𝑘
‒1）+𝑗
））,wherek=1,2….6.The
doublethecoordinateofthe
firstlooppoints
diagnoseofaparallelogram
secondloopcanbecalculatedbythefirstloop.Therearetwokindsofsecondloopco-channelbasestation.Onecanbecalculatedbydoublethecoordinateofthefirstlooppoints.Theothercanbedonebyaddingcoordinatesofadjacentfirstlooppointasitisthediagnoseofaparallelogram.Examplesofthosetwokindsofpoints,point1and2,canbefoundinfigure3
Figure3calculatecoordinateofco-channelbasestationbyIJpair
AdjCel.m
%**************************************************************************
%Thisfunctionistofindcellularscoordinatesx+jy
%（BaseStationsinthemiddle）foragivenN（soasi/j）
%CelLocisa18*1matrixwiththecoordinatesoftheco-interference
%cellofthefirsttwocycle.（6forthefirstcycleand12forthesecond）
%**************************************************************************function[CelLoc]=AdjCel（N）
%********CallClusterNfunctontogettheiandjvalue*******%[ii,jj]=ClusterN（N）
%********18locationsconsideringtwocycleofco-interferencecell*******%CelLoc=zeros（18,1）+j*zeros（18,1）;
%********calculatethefirstco-interferencecell*******%CelLoc
（1）=sqrt（3）*（ii*exp（j*pi/6）+jj*exp（j*pi/6+j*pi/3））;
%********theothercellsare60degreeshiftofthelastcell*******%fork=2:
6
CelLoc（k）=CelLoc（k-1）*（0.5+sqrt（3）/2*j）;
end;
%********thesecond12co-interferencecellsarethevectoraddtionofthefirstcycle*******%
fori=1:
CelLoc（2*i+5）=CelLoc（i）+CelLoc（i）;
CelLoc（2*i+6）=CelLoc（i）+CelLoc（i+1）;
CelLoc（18）=CelLoc（6）+CelLoc
（1）;
（4）NowwehavecoordinatesofMSandco-channelbasestation,sowecancalculateSIRby
（𝑑
𝑚
𝑠
）‒𝑛
𝑆
𝐼
𝑅
=18
∑
）‒𝑛
𝑑
theformula
𝑖
=1
𝑏
,where
𝑚
standsforthedistancefromMStothecenter
while
𝑑
𝑏
standsforthedistancefromtheco-channelbasestationtotheMS.We
simulatedit100000times.
%ForwardLink
clearallcloseall
N=input（'
theclustersizeN='
）;
n=input（'
thepathlossexponentn='
）M=100000;
%thetimesofsimulation
%***callfunctiontogettherandomlylacationoftheuser***%MSPos=RandPOS（M）;
%***callfunctiontogetthelacationof18co-interferencecells***%CelLoc=AdjCel（N）;
%***dsisthe'
-n'
powerofthedistancebetweenMSandBaseStation***%ds=（abs（MSPos））.^-n;
%***calculatethe'
powerofthedistancebetweenMSandBaseStationoftheco-interferencecell***%
ditemp1=abs（MSPos*（ones（18,1））'
-ones（M,1）*CelLoc'
ditemp2=ditemp1.^-n;
%***addthedistanceofinteferencetogather.***%di=ditemp2*ones（18,1）;
%***theSIR***%SIR=10*log（ds./di）;
%EverageSIR=SIR*ones（1,M）/Mhist（SIR,[-20:
250]）
title（'
Histogram'
xlabel（'
SIR（dB）'
ylabel（'
numbersofMS'
（5）Rsults:
WewillsimulatetheSIRoftheco-interferenceoftheforwardinglinkwithdifferentclustersize‘N’andpathloseexponent‘n’andplaintthehistogramofeachcondition.Tomakeacomparison,wechosetwogroupofnandNas:
Whenn=3.6,weletN=1,3,4,7,12.WhenN=7,weletn=2,3,3.5,4.
IftherandomMSistoonearlytothebase
station,d<
𝑑
0ord=0,theSIRwillbetoohigh.
Sowhend<
0,weletd=𝑑
0toremovetheBS.
.0istherangeofthebasestation.
（𝑑
）‒𝑛
Figure5histogramofSIRwhileN=1,n=3.6
Figure6histogramofSIRwhileN=3,n=3.6
Figure7histogramofSIRwhileN=4,n=3.6
Figure8histogramofSIRwhileN=7,n=3.6
Figure9histogramofSIRwhileN=12,n=3.6
Figure10histogramofSIRwhileN=7,n=2
Figure11histogramofSIRwhileN=7,n=3
Figure12histogramofSIRwhileN=7,n=3.5
Figure13histogramofSIRwhileN=7,n=4
WecanseefromthehistogramthattheaverageSIRincreasewithNincrease.Sincethedistancebetweentheclusterandtheco-interferencecellislargerwhenNislarger,sotheco-interferenceissmaller.ForaconstantclustersizeN,theSIRislargerasthepathloseexponentbecomeslarger.Sincewhennischanging,theco-interferencepowerisreducedmuchmorethanthesignalpower.Eventhoughthesystemwilllosemorepower,theSIRisbecomeslarger.
2.WriteaprogramtocalculatetheSIRinthereverselink,andrepeatsitbyrandomlychangingthepositionsoftheMSs.（Notethattheinterferencesinthereverselinkaregeneratedbyco-channelMSsandisdifferentfromtheinterferenceintheforwardlink.）Afteranumberofsimulations,usethesimulatedresultstodrawthehistogramoftheSIR.TrytoobtainhistogramswithdifferentpathlossexponentnandclustersizeN.Concludeyourresults.
Theco-channelinterferenceinthereverselinkcanbecharacterizedin
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