?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.relation=http%3A%2F%2Fmiis.maths.ox.ac.uk%2Fmiis%2F324%2F&rft.title=Mobile+radio+propagation+prediction+using+ray+tracing+methods&rft.creator=Allwright%2C+D.J.&rft.creator=Chapman%2C+S.+J.&rft.creator=Smyshlyaev%2C+V.&rft.creator=Ockendon%2C+J.R.&rft.creator=Lawry%2C+J.&rft.creator=Saward%2C+V.&rft.creator=King%2C+J.&rft.creator=Chapman%2C+J.&rft.creator=Tew%2C+R.&rft.creator=Howls%2C+C.&rft.creator=Lacey%2C+A.A.&rft.creator=Lee%2C+G&rft.subject=Information+and+communication+technology&rft.description=The+basic+problem+is+to+solve+the+two-dimensional+scalar+Helmholtz+equation+for+a+point+source+(the+antenna)+situated+in+the+vicinity+of+an+array+of+scatterers+(such+as+the+houses+and+any+other+relevant+objects+in+1+square+km+of+urban+environment).+The+wavelength+is+a+few+centimeters+and+the+houses+a+few+metres+across%2C+so+there+are+three+disparate+length+scales+in+the+problem.%0D%0A%0D%0AThe+question+posed+by+BT+concerned+ray+counting+on+the+assumptions+that%3A%0D%0A%0D%0A(i)+rays+were+subject+to+a+reflection+coefficient+of+about+0.5+when+bouncing+off+a+house+wall+and%0D%0A%0D%0A(ii)+that+diffraction+at+corners+reduced+their+energy+by+90%25.+The+quantity+of+particular+interest+was+the+number+of+rays+that+need+to+be+accounted+for+at+any+particular+point+in+order+for+those+neglected+to+only+contribute+10%25+of+the+field+at+that+point%3B+a+secondary+question+concerned+the+use+of+rays+to+predict+regions+where+the+field+was+less+than+1%25+of+that+in+the+region+directly+illuminated+by+the+antenna.%0D%0A%0D%0AThe+progress+made+in+answering+these+two+questions+is+described+in+the+next+two+sections+and+possibly+useful+representations+of+the+solution+of+the+Helmholtz+equations+in+terms+other+than+rays+are+given+in+the+final+section.&rft.date=1996&rft.type=Study+Group+Report&rft.type=NonPeerReviewed&rft.format=application%2Fpdf&rft.language=en&rft.identifier=http%3A%2F%2Fmiis.maths.ox.ac.uk%2Fmiis%2F324%2F1%2FMobile-phones-BT.pdf&rft.identifier=++Allwright%2C+D.J.+and+Chapman%2C+S.+J.+and+Smyshlyaev%2C+V.+and+Ockendon%2C+J.R.+and+Lawry%2C+J.+and+Saward%2C+V.+and+King%2C+J.+and+Chapman%2C+J.+and+Tew%2C+R.+and+Howls%2C+C.+and+Lacey%2C+A.A.+and+Lee%2C+G++(1996)+Mobile+radio+propagation+prediction+using+ray+tracing+methods.++%5BStudy+Group+Report%5D+++++