Automatic Transmit Power Control of a Digital Fixed Wireless Link

8/3/2019 Automatic Transmit Power Control of a Digital Fixed Wireless Link

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San Jose State University SJSU ScholarWorks

Faculty Publications Electrical Engineering Department

1-1-2007

Automatic Transmit Power Control of a DigitalFixed Wireless Link with Co-Channel InterferenRobert H. Morelos-ZaragozaSan Jose State University , [email protected]

Kyoung-Whoan Suh Kangnam University

Joo-Hwan Lee Electronics and Telecommunications Research Institute (ETRI)

This Article is brought to you for free and open access by the Electrical Engineering Department at SJSU ScholarWorks. It has been accepted forinclusion in Faculty Publications by an authorized administrator of SJSU ScholarWorks. For more information, please [email protected].

Recommended CitationMorelos-Zaragoza, Robert H.; Suh, Kyoung-Whoan; and Lee, Joo-Hwan, "Automatic Transmit Power Control of a Digital Fixed Wireless Link with Co-Channel Interference" (2007).Faculty Publications.Paper 23.http://scholarworks.sjsu.edu/ee_pub/23
http://scholarworks.sjsu.edu/http://scholarworks.sjsu.edu/ee_pubhttp://scholarworks.sjsu.edu/eemailto:[email protected]:[email protected]:[email protected]:[email protected]://scholarworks.sjsu.edu/eehttp://scholarworks.sjsu.edu/ee_pubhttp://scholarworks.sjsu.edu/


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A u t o m a t i cT r a n s m i tPower C o n t r o lof a D i g i t a lFixed Wireless Link with Co-Channel

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A b s t r a c t -I n t h i spaper, a s t u d y i s p r e s e n t e do f th e d y n a m i cb e h a v i o rof an a u t om a t ic t r an s mi tpower con t ro l (ATPC) l o o p i na s i n g l ef i x e d w i r e l e s ss y s t e m(FWS) l i n k s u b j e c tt o m u l t i p a t hf a d i n ga n d a n u n c o r r e l a t e dc o - c h a n n e li n t e r f e r e r t h a t d o e s n o tu se ATPC ( t h i sr e p r e s e n t sa s o - c a l l e dn o n - AT P C FWS l i n k or af i x e ds a t el l i t e l i nk ) .F u n d a m e n t a lq u e st io ns i nc l ud e t h es e n s i t i v i t yof a n ATPC l i n k t o m u l t i p a t hi n t e r f e r e n c ea n d th e c o - c h a n n e li nt e rf e r e nc e t h atmay b e c a u s e db y a n o n - AT P C i n t e r f e r e r .I n th ec o n t e x to f th e p r e s e n tp r o j e c t ,a g oo d e x am p l eof a n o n - AT P Cin t e r fe re r i s a f i x e ds a t e l l i t eto w h i c hon e a n t e n n ai n a f i x e dm i c r o w a v el i nk h a s p a r t i a l v i e w. A computer m o d e l wasd e v e l o p e dt h a t cons t i tu t e sa u s e f u l t o o li n d e s c r i b i n g ;s i m u l a t i n ga n da n a l y z i n gan ATPC l o o p i n a s i n g l eFWS l i n k .With th e a id o ft h i sm o d e l ,r e s u l t sar e p r e s e n t e don th e s e n s i t i v i t yo f a n ATPCl o o p i n a FWS l i n k w i t h r e s p e c tto c h a n n e lcond i t ions ,non-ATPCi n t e r f e r e n c ea n dp a r a m e t e rs e t t i n g s .

I n d e xTerms-Power Con t ro l ,F i x e dWi r e l e s s .

I. INTRODUCTION

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ADITIONALLY, automatic t r a n s m i tpower c o n t r o l( AT P C )t e c h n i q u e sh a v eb e e nu t i l i z e di nm i c r o w a v er a d i ol i n k si n o r d e rto c o m b a tr a i nf a d i n g( a t t e n u a t i o n ) .T h i si s a l s os o m e t i m e sr e f e r r e dto as power d i v e r s i t y.I n i t i a l l y,t h el i n ki sd e s i g n e ds u c ht h a tt h e t r a n s m i t t e rp o w e r i s s u f f i c i e n t l yl a r g etoa c h i e v ea g i v e nq u a l i t yof s e r v i c eg o a l ,s u c ha s b i terror r a t e ,u n d e rc l e a rs k y c o n d i t i o n s .When t h e l i n ke x p e r i e n c e sa na t t e n u a t i o nd u e to r a i n ,t h e t r a n s m i tpowe r i s i n c r e a s e dg r a d u a l l ya n du p to t h emaximumt r a n s m i s s i o npower l i m i ts e tb y a g o v e r n m e n ta u t h o r i t y .T h ep a r t i c u l a rt e c h n i q u eu s e d i ni n c r e a s i n gor d e c r e a s i n gpower a t t h e t r a n s m i t t e r ,a n d t h em e t h o dof e s t i m a t i n gpower a t t h er e c e i v e r ,c a n b e u s e dt od i f f e r e n t i a t eAT P Ct e c h n i q u e sor a l g o r i t h m s .T oi l l u s t r a t e[ 2 7 ]t h ef u n d a m e n t a li d e a sb e h i n dt h eu se o f AT P Ct e c h n i q u e si nf i x e d w i r e l e s ss y s t e m s ,cons ide rt h ecase o f t wo FW S l i n k s .

M a n u s c r i p tr e c e i v e dMarch 3 1 ,2 0 07 . T hi swork was s u p p o r t e di npar t b yt h e E l e c t r on i csa n dTe l e c o m m u n i c a t i o n sR e s e a r c hI n s t i t u t e( E T R I ) ,K o r e a .

R . H . M o r e l o s - Z a r a g o z ai s w i t h S a nJ o s e S t a t eU n i v e r s i t y ,S a nJ o s e ,CA9 5 1 9 2 - 0 0 8 4USA ( p h o n e : 1 - 4 0 8 - 9 2 4 - 3 8 7 9 ;f a x : 1 - 4 0 8 - 9 2 4 - 3 9 2 5 ;e - m a i l :r . m o r e l o s - z a r a g o z a Ai e e e . o r g ) .

F. W. S u h . ,i s w i t h t h e R e s e a r c hI n s t i t u t eo f Indus t r ia l -Educa t iona lTe c h n o l o g yo f K a n g n a mU n i v e r s i t y ,K o r e a( e - m a i l :k w s u h A k a n g n a m . a c . k r ) .

J . H . L e e i s w i t h t h e E l e c t r o n i c sa nd T e le c om mu ni ca ti on s R e se a rc hI n s t i t u t e( E T R I ) ,K o r e a( e - m a i l :j o o h l e e A e t r i . r e . k r ) .

U n d e rn o n - r a i n yc o n d i t i o n s ,e a c h l i n k h as a nomina lt r a n s m i t t e dp o w e rt h a ti s r e q u i r e di n o r d e rt o a c h i e v ea g i v e nq u a l i t y .T h i sq u a l i t ym e a s u r ec an b e f o re x a m p l et h eb i te r r o rr a t e( BE R ). S u p po sen ow t h a tl i n kA i s s u b j e c tt o r a i nf a d i nw h i l e a t t h e s a m e t ime l i n kB r e m a i n su n d e r c l e a r - s kc o n d i t i o n s .T h ep r e s e n c eo f a n AT P C l o o pi n l i n kA w i l li n c r e a s e t h et r a n s m i t t e dp o w e ri n o r d e rt o o v e r c o m et h ed r o pi nr e c e i v e dp o w e ran ds u b s e q u e n tl o s sof q u a l i t y( f o re x a m p l e ,a n i n c r e a s ei nb i t e r r o rr a t ev a l u e ) .T h i sw i l lw o r kf i n eo n l i n kA . H o w e v e r ,i t i s a l s op o s s i b l et h a tl i n kB w i l lr e c e i v es o m eo ft h ep o w e rs e n tb y t h e t r a n s m i t t e r si n l i n kA a n dt h e r e f o r ew i l ls u f f e rc o - c h a n n e li n t e r f e r e n c e( C C I ) .T h e i n t r o d u c t i o no f ad i f f e r e n t( u n c o r r e l a t e d )s i g n a lp o w e ri n l i n kB w i l lg i v ea s ar e s u l ta l o s so f l i n kq u a l i t y( a sa n o t h e re x a m p l e ,t h i sc o u l db ea n i n c r e a s e doutaget i m e ) .

A . T h euseo f AT P Ct e c h n i q u e si nw i r e l e s sn e t w o r k sI nr e c e n ty e a r s ,t h eus e o f AT P Ct e c h n i q u e st o i n c r e a s et h e

r e l i a b i l i t yan d e f f i c i e n c yof w i r e l e s sn e t w o r k san d f i x e dm i c r o w a v el i n k sh as i n c r e a s e ds u b s t a n t i a l l y .I n 2 0 0 1 , t h e

F e d e r a lC o m m u n i c a t i o n sC o m m i s s i o n( F C C )a p p r o v e dt h eus eo f AT P C i n B r o a d c a s tA u x i l i a r yS e r v i c e so p e r a t i n gi n t h e2G H z ,7 GHzan d1 3GHzb a n d s[ 3 ] . S i n c e1 9 9 6 w h e nt h eC o m m i s s i o na m e n d e di t sP a r t1 0 1r u l e s ,AT P Ch asb e e nu s e ds u c c e s s f u l l yi n t h eF S m ic ro wav eb a n d s .Wi t hr e s p e c tt o t h emaximumt r a n s m i tp o w e rl i m i t ,t h eFC C r u l e si np a r t7 4 . 5 3 5f o rt h e2 G H z ,6 . 4G H z , 7 G H z ,1 3GHz a n d 18 GHz b a n d st h a t" T h eEIRP of t r a n s m i t t e r st h a tu se Au to ma t i cT r a n s m i tP o w e rCont ro l( AT P C )s h a l lno t e x c e e dt h eEIRP s p e c i f i e do nt h es t a t i o na u t h o r i z a t i o n .T h eEIRP of non-ATPCt r a n s m i t t es h a l lb e ma in ta in eda s n e a r a s p r a c t i c a b l et o t h e EIRPs p e c i f i e do n t h es t a t i o na u t h o r i z a t i o n . "[ 4 ] .

I n a 2 0 0 3 r e p o r t[ 5 ] , i t i s s t a t e d t h a tAT P C a l l o wt r a n s m i t t e r st o o p e r a t ew i t ha c e r t a i n"nomina lp o w e r "d u r i nn o r m a lp r o p a g a t i o nc o n d i t i o n s .I ft h er e c e i v e rd e t e c t sa d ropi nr e c e i v e ds i g n a ll e v e l ,t h et r a n s m i tp o w e ri s i n c r e m e n t a l lo ri n s t a n t a n e o u s l yi n c r e a s e dt o t h emaximuma l l o w a b l ep o w e rl e v e l ,d e p e n d i n go n t h e manufac ture r ' sd e s i g n .Rad iose q u i p p e dw i t hAT P Ch a v et h ef o l l o w i n ga d v a n t a g e so v e rt h e i rnon-ATPCe q u i p p e dc o u n t e r p a r t s :

1 )S i m p l i f i e df r e q u e n c yc o o r d i n a t i o ni nc o n g e s t e da r e a s2 )L e s sp o w e rconsumpt ion3 )I n c r e a s e dMTBF ( M e a nt imeb e t w e e nf a i l u r e s )


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T h ea p p l i c a t i o no f AT P Ct e c h n i q u e si n f i x e dw i r e l e s sl i n k so p e r a t i n gi n t h e7 0 / 8 0GHz b a n d si s p r e s e n t e di n [ 7 ] .M o s tr e c e n t l y ,i n t h e U . S . A . ,t h eA d v a n c e dT e l e v i s i o nS y s t e m sC o m m i t t e e( AT S C )h as p r o p o s e da new s t a n d a r dt h a ti n co r p o r a t e s t h eus e of AT P Ct e c h n i q u e s[ 8 ] .No d e t a i l sa r eg i v e nh o w e v e ron e x a c t l yh ow t h eAT P Ct e c h n i q u ei s t o b ei m p l e m e n t e d ,b u tr a t h e ra p r o v i s i o no f a f e e d b a c kl i n kwitham e a s u r eo f t h e r e c e i v e dp o w e rm a d e a v a i l a b l et o t h et r a n s m i t t e r .T o f u r t h e ri l l u s t r a t eo t h e ra p p l i c a t i o n sof AT P Ct e c h n o l o g ywe n o t et h a t , i n t h e 2 GHz b a n d ,W i r e l e s sC o m m u n i c a t i o n sA s s o c i a t i o nI n t e r n a t i o n a l ,I n c . ( T I A )s u b m i t t e da d o c u m e n tt o t h eFC C i n w h i c hAT P C p l a y sac e n t r a lr o l e[ 9 ] .

C o n s i d e r a t i o n sof AT P C t e c h n o l o g ya p p l i c a t i o n si n f i x e dw i r e l e s sn e t w o r k s ,s u c ha sW i M a x ,a p p e a ri nt h eI E E E8 0 2 . 1 6s t a n d a r dsubg roupi n c h a r g eof p o i n t - t o - m u l t i p o i n tl i n k s[ 1 1 ] .T h eI E E Es t a n d a r df o rWiMax[ 1 6 ]s t a t e s ,i n s e c t i o n8 . 1 . 1 1 . 2 ,o n t h es u b j e c to f S S - t o- B Si n t e r f e r e n c et h a t :" I n P M Ps y s t e m s ,S S - t o - B Si n t e r f e r e n c em ay b e e v a l u a t e db yuse o f a s i m u l a t i o np r o g r a m .I t i s c le a r t ha ta n i n t e r f e r i n gS Scoul d b er e l a t i v e l y

c l o s et o a v i c t i mB S ,b u tt h el e v e lof i n t e r f e r e n c ed e p e n d so nt h er e l a t i v el o c a t i o n sof t h eB S so f t h et w o s y s t e m s( w h i c ha f f e c t st h ea n t e n n ap o i n t i n gd i r e c t i o n ) ,o n t h eus e of automatict r a n s m i tp o w e rc o n t r o l( AT P C ) ,a n d o n p o s s i b l ed i f f e r e n t i a lr a i n f a d i n g .

A n o t h e rp o t e n t i a la d v a n t a g eo f AT P C t e c h n o l o g yi s i nL M D Ss y s t e m s ,w h e r ei t i s c l a i m e dt h a t ,withp o w e rc o n t r o l ,t h ec a r r i e r - t o - i n t e r f e r e n c e( C / I )r a t i oc a n b e imp rov ed b ya tl e a s t2 d B [ 1 2 ] .AT P Ct e c h n i q u e sa l s of i n da p p l i c a t i o n si ni n t e r f e r e n c e c a n c e l l a t i o nb e t w e e ns a t e l l i t ean d t e r r e s t r i a ls y s t e m si n t h e2 8 GHz b a n d .T om i n i m i z et h ec a r r i e rp o w e r,a u t o m a t i ct r a n s m i t t e rp o w e rc o n t r o l( AT P C )i s e m p l o y e da tt h e g r o u n dt e r m i n a l s ,a n d a l s oa t t h e s a t e l l i t e si n s o m ep r o p o s e dN G S O s y s t e m s .When f a d i n ge v e n t soccur ( f o re x a m p l e ,u n d e rr a i nc o n d i t i o n s )t r a n s m i t t e rp o w e ri s i n c r e a s e dt o c o m p e n s a t ef o r t h e a d d i t i o n a ll o s s .T h e us e o f AT P Cm i n i m i z e sp o w e rc o n s u m p t i o nu n d e rc l e a r - s k yc o n d i t i o n san dt h e r e f o r ee a s e st h ep r o b l e mof s h a r i n gs p e c t r u mwith o t h e rn e t w o r k sb yr e d u c i n gt h ep o t e n t i a li n t e r f e r e n c e .

A s t u d y[ 1 3 ]u s e sa n AT P Cr a n g ee q u a lt o 1 0 d B .I nt h e4 3GHz b a n d[ 1 4 ] ,AT P Cp r o v i d e sa t r a n s m i s s i o np o w e rr a n g ef r o m- 3 0dB Wd o w nt o - 5 0 dBW. T h eus e a n dl i m i t a t i o n so fAT P C t e c h n i q u e s ,i n p o i n t - t o - p o i n tw i r e l e s ss y s t e m so v e rh i g h e rf r e q u e n c yb a n d s ,i s a l s od i s c u s s e db y t h eF C C [ 1 8 ] .M o r e o v e r ,o n t h et o p i cof e a r t hs t a t i o n si n s a t e l l i t es y s t e m s ,t h e f o l l o w i n gw a s r u l e db y t h e R A B C F i x e d W i r e l e s sC o m m u n i c a t i o n sC o m m i t t e e [ 2 4 ] :

T h eE u r o p e a nU n i o nh as a l s oi s s u e dr e c o m m e n d a t i o n so nt h eu s e o f AT P Ci n f i x e d - s a t e l l i t es e r v i c e s[ 2 5 ] :" t h a tt h eu s eof t r a n s m i tp o w e rr e d u c t i o nm e c h a n i s m s( e . g .A u tom a t i cP o w e rC o n t r o la n d / o rP o w e rS e t t i n g )b y t h eFWA t e r m i n a ls t a t i o n sw i l le n s u r e t h a tt h emaximumEIRP d e n s i t yl e v e ld e f i n e di n c o n s i d e r i n gm ) w i l lno t b e e x c e e d e db y a s i n g l es t a t i o nt o w a r d st h eGS O a r c ; "an d " t h a tFSS s y s t e m su s i n g

TA B L EIPA R A M E T E R SO FT H ECOMPUTERMODELO FA NFWSL I N K

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D e c i d e1 an d2 s h a l li m p l e m e n tAut o m a t i cP o w e rCont ro li nt h euncoord ina tedFSS e a r t hs t a t i o n sa n d / o rau tomat icon-b o a r d s a t e l l i t eg a i nc o n t r o l ; "A l s o i n E u r o p e , AT P Ct e c h n i q u e sh a v e b e e n i n t e g r a t e di n t os o - c a l l e d" Te c h n i c a lF r e q u e n c yA s s i g n m e n tC r i t er i a f o rL o w e r6 an dU p p e r6 GHzB a n d s "[ 1 5 ] .

T od a t e ,t h eb e s ts t u d yo n t h ev a l i d i t yo f AT P Ct e c h n i q ui nf i x e dd i g i t a lw i r e l e s ss y s t e m si s t h a tp r o d u c e db yt h eO f c o mg r o u pi n t h eUK [ 2 6 ] .I np a r t i c u l a r ,t h es t u d yc o n c l u d e st h a t :" T h ep o t e n t i a la dv an ta g es o fAT P Cr e p o r t e di n t h el i t e r a t u ri n c l u d e( i )R e d u c e da v e r a g ep o w e rconsumpt ion ;( i i )e x t e n d e de q u i p m e n tmean t imeb e t w e e nf a d e s( M T B F ) ;( i i i )El imina t iono f t h e ' u p f a d e 'p r o b l e mi n r e c e i v e r s ;( i v )I m p r o v e doutagep e r f o r m a n c ed uet o t h er e d u c e di n f l u e n c eo f a d j a c e n tc h a n n e li n t e r f e r e n c e( A C I ) ;an d ( v )e a s i e rf r e q u e n c yc o - o r d i n a t i oi na r e a so fh i g hr a d i o - r e l a ys t a t i o nd e n s i t y . "

I I . MODELOF A NAT P CFIXEDWIRELESSL I N K

A . S y s t e mm o d e lA c o m p u t e rm o d e lw a sd e v e l o p e dt o f a c i l i t a t et h es t u d yo f

t h ep e r f o r m a n c eof AT P C t e c h n i q u e si n a n FWS l i n kw i t hr e s p e c tt o r a i na t t e n u a t i o n ,c o - c h a n n e li n t e r f e r e n c e( C C I ) ,a n dl o o pp a r a m e t e rs e t t i n g s .I n i t sc u r r e n tf o r m ,t h i sm o d e la p p l i et o a 3 0 MHz b a n d w i d t hf r e q u e n c yb a n dan di t i s i m p l e m e n t ei n t h e c o m p l e xb a s e b a n dd o m a i n .( T h i si s d o n e f o r t h ep u r p o s e so f s h o r t e n i n gt h es i m u l a t i o nt i m e .I t s h o u l db e n o t e dt h a ta f u l lRF ( b a n d p a s s )m o d e lc o u l db e e a s i l yi m p l e m e n t e dH o w e v e r ,t h es i m u l a t i o nt imew o u l db e t oo l a r g e . )T h e m o d eh a sb e e n i m p l e m e n t e du s i n gM a t l a b T Ms o f t w a r ewith t h e

S i m u l i n k T Mt o o l a n d t h e C o m m u n i c a t i o n sa n d S i g n aP r o c e s s i n gB l o c k s e t s .T h e m a i n m o d e lp a r a m e t e r sa r es u m m a r i z e di n Ta b l eI . I m p o r t a n t l y ,we no te t h a tt h em o d e la s s u m e sa n i d e a lr e t u r nc h a n n e lw i t h o u tn o i s eo v e rw h i c ht h er e q u i r e dt r a n s m i t t e rg a i nf a c t o ri s c o n v e y e d .T h e r a i na t t e n u a t i o nf a c t o rG i s a g a i nt h a ti s c o m p u t e df r o mt h e r a ia t t e n u a t i o nA ( i nd B )a sf o l l o w s :

G 1 0 - A / 2 0 ( 1 )u n c o o r d i n a t e dF S Se a r t hs t a t i o n si n t h eb a n d sr e f e r r e dt o i n T h e t r a n s m i s s i o ng a i nf a c t o rG TXa t t h e t r a n s m i t t ei s


4/8

06 07

F i g .1 . M a g n i t u d es p e c t r u mof a n a r r o w b a n dl o w p a s sf i l t e r( L P F ) ,u s e di ne s t i m a t i o nof t h er e c e i v e dp o w e r

i n i t i a l l ys e te q u a lto 1 ( t h i sc o r r e s p o n d sto a v a l u eo f 0 d B i npower i n c r e a s e )a n d i s m o d i f i e dp e r i o d i c a l l yb y t h eAT P Cc o n t r o ll o o p ,b a s e d on t h e average r e c e i v e dpower, ase x p l a i n e db e l o w.T h u sa n impor tan tp a r a m e t e ro f an AT P Ct e c h n i q u eor a l g o r i t h mi s t h er a t ea t w h i c ht h eloop o p e r a t e s .T h i si s s u ei s a d d r e s s e di na l a t e rs e c t i o n .

c o m p u t i n ga t ra n s mi t t e rg a i nf a c t o rGT r e q u i r e da t t h et r a n s m i t t e re n dof a l i n ki n o r d e rt o r e a c ha d e s i r e da v e r a g ep o w e ra t t h er e c e i v e re n d .F o r e x a mp le , a nAT P Ca l g o r i t hw a s b e e na p p l i e dt o c e l l u l a rs y s t e m si n [ 3 2 ] .I n t h eS J S Um o d e l ,an do n l yf o rc o n v e n i e n c e ,t h et a r g e ta v e r a g ep o w e rh asb e e ns e tt ou n i t y .T h i sc a nb e e a s i l yc h a n g e dt o o t h e rv a l u e si fd e s i r e d .

T h ea v e r a g er e c e i v e dp o w e ri s a v a i l a b l ea t t h eoutputo f ad i g i t a ln a r r o w b a n dl o w p a s sf i l t e r ,a s e x p l a i n e da b o v e .L e tP R [ n ]d e n o t et h ees t ima teda v e r a g er e c e i v e dp o w e r.B a s e do nt h ev a l u eP R [ n ] ,t h eAT P Ca l g o r i t h mc o m p u t e sa p o w e rs t e p

( 2 )

w h e r eg ( d e n o t e sa non l inea rf u n c t i o nw h i c hi s e s s e n t i a l l yt h ec o mb i n a ti o n o fa d e a dz o n e a n da t w o - l e v e lq u a n t i z e r .

T h ep a r a m e t e r so f t h i snonl inea rf u n c t i o nd e p e n don pre-s p e c i f i e dpower s t e p s t h a tare u s e d to i n c r e a s eor d e c r e a s e

p o w e r a t t h e t r a ns mi t t e r . I nt h i s w o r k , t h e i n c r e m e n t si nt r a n s m i t t e dpower are s e t to s ta nd a rd v a lu e so f d B .T h e s ev a l u e sare f o u n dto b e s t a n d a r di n many c o m m e r c i a lAT P Cproduc t si n t h em a r k e t .T h eAT P Ca lg o ri th m t h e np r o c e e d stoc o m p u t et h ev a l u eof t h enew r e q u i r e dt r a n s m i t t e rpower asf o l l o w s :

P T[ n + 1 ]= ( I+ A P ) P T[ n ]B . M u l t i p a t hc h a n n e lm o d e lT h e mul t ipa thc h a n n e lm o d e lu s e d i n t h i ss t u d yi s t h e

s t andardt h r e e - p a t hc h a n n e lm o d e lp r o p o s e db yRummler [ 2 9 ] .T h epa th d e l a yt i s c o m p u t e dus ingt h e s o -c a l l e df a c t o r - o f - s i xr u l e[ 30 ] , [ 31 ] ,= I / 6 f B ,w h e r efB =(I+a)R i s t h ec h a n n e lb a n d w i d t ha n d o c = 0 . 2 5i s t h er o l l - o f ff a c t o rof t h es q u a r e - r o o tr a i s e d - c o s i n ef i l t e r su s e d a t t h e t r a n s m i t t e ra n dr e c e i v e r.

I I I . PROPOSEDAT P CA L G O R I T H M

A . Power measurementT h emet r i cu s e d to d r i v et h eAT P C loop i s t h er e c e i v e d

power. I t i st h e r e f o r every impor tan tto obta in a r e l i a b l ea n da c c u r a t ees t imateo f t h er e c e i v e dpower. I n t h eSJSU m o d e l ,t h er e c e i v e dpow er i s e s t i m a t e di nt h ed i g i t a lb a s e b a n dd o m a i nas f o l l o w s .T h em a t c h e df i l t e ro u t p u t sare s a m p l e da t s y m b o lr a t e ,a n dt h esquare m ag n i tu d e s c om p ut e d .T h e s en u m b e r saret h e np a ss e d t h ro ug ha d i g i t a l2 n do r d e rC h e b y s h e vt y p e - I II I Rn a r r o w l o w p a s sf i l t e r( L P F ) .T h i sf i l t e rwas d e s i g n e dus ingt h eF i l t e rD e s i g na n d A n a l y s i s( F D A )t o o li n M a t l a b ' T ma n d wass p e c i f i e dto h a v ea n o r m a l i z e ds t o p b a n df r e q u e n c ye q u a lto0 . 0 5w i t ha n a t t e n u a t i o nv a l u eo f 8 0d B .F i g .1 s h o w sa p l o to ft h em a g n i t u d es p e c t r u mo f t h ef i l t e r .

B . A l g o r i t h mA n AT P C a l g o r i t h mi s h e r e b yd e f i n e das a m e t h o dof

( 3 )

T his v al uen e e d st o b e s a t u r a t e di n o r d e rn o t to e x c e e dt h emaximuma l l o w a b l et r a n s m i tpower. I n t h eAT P Cm o d e l ,t h ea lgor i thmh as a 3 0 dB range, w i t h t h eminimumt r a n s m i t tpower s e t to 1 ( 0 d B )a n d t h emaximumt r a n s m i t t e dp o w e re q u a lto 1 0 0 0( 3 0d B ) .F i n a l l y ,t h ev a l u eo f t r a n s m i t t e rg a i nf a c t o rG Ti s o b t a i n e das G T= J P T[n + 1 ]

C . AT P CloopOn e o f t h ec o n t r i b u t i o n so f t h ew o r kr e p o r t e dh e r ei s i nt h ea n a l y s i so f t h ed y n a m i c so f t h eAT P Cc o n t r o ll o o p .T h i si s ap r o b l e ms i m i l a rto t h a to f p h a s e - l o c k e dl o o p s( P L L )i nt h esense t h a tf e e d b a c ka n dn o n l i n e a rf u n c t i o n sare i n v o l v e d .T h u sof g r e a ti n t e r e s ti s t h ed y n a m i cb e h a vi or o ft h eAT P Cc o n t r o lloopw i t hr e s p e c tto var iousp a r a m e t e r ss u c has r a i na t t e n u a t i o nl e v e l ,AT P Cs t e ps i z ea n dAT P Cu p d a t ei n t e r v a l .

I V . R E S U LT S

A. S e n s i t i v i t yto AT P Cloop s a m p l i n gr a t eI t i s impor tan tt h a tt h e AT P C c o n t r o lloop b e u p d a t e d

s l o w l y .T h i smeans t h a tt h es a m p l i n gp e r i o do f t h eloopn e e d sto e x c e e dt h e l e n g t ho f t h ei m p u l s eresponse o f t h ed i g i t a la v e r a g i n gf i l t e r .O t h e r w i s e ,an uns tab les i t u a t i o nw i l lo c c u r , a sw i l lb e s h o w ns h o r t l y ,w h e r eb o t h t h e t r a n s m i t t e rg a i nf a c t o rG Ta n d t h ee s t i m a t e daverage r e c e i v e dpower P R [ n ]o s c i l l a t

- 20

- 4 0 1 LJ

-2 0 -----,----n --- - - - - - - - - - -- - - -- -- - -l-- - -- - -- - - -- -T--- ---- l-----

60 - - - - - - - - - - - --

0 0

-1

A P = g ) ,( I P ,[ n ]-1 ) ,1


5/8

Fig. 2. Dynamic behavior of the average power and transmitter g a i n factor

for DTT =100

around the desired (s teady) values.

In the SJSU model, the ATPC loop is activated once every DT

s e c o n d s , where DT is a mult ip le of the symbol period T , and

can be set by the user.

To i ll us t ra t e t h is point, the SJSU model was run us ing a

normalized loop s a m p l i n g interval equa l to D T / T = 1 0 0 ,andrain attenuation A= 3 dB. Clearly, the ATPC loop becomes

unstable and o s c i l l a t e s , as shown in Fig. 2. around the desired

values. Both the estimated average received power P [ n ]

(shown on the top) and the transmitter ga in factor GT (shown

on the b o t t o m ) oscillate and as a result the link will eventual ly

fail.

As Figures 3 to 5 show, increas ing the value of the s a m p l i n g

period ( i . e . , decreas ing the s a m p l i n g rate) of the ATPC loop

improves s t a b i l i t y . In the results reported in these figures, the

rain attenuation was set to A= 3 dB. We also see from these

results that the value of the estimated average power remains

within a value of dB from the t a rg e t value ( 0 dBW), jus t as

expected. Using a normalized s a m p l i n g period of DT/T =200results in an estimated mea n received power approx ima te ly

equa l to ( the desired value). On the other h a n d , a value of

DT/T =500 results in a mean value g r e a t e r than 1 , and a valueof DT/T =1000 results in a mean value less than uni ty.

B. Sensitivity to rain attenuation

The model was used to ana lyze the effect of rain attenuation

A (dB) on the p e r f o r m a n c e of an ATPC loop us ing a fixed

s a m p l i n g factor DT/T = 2 0 0 . Rain attenuation values of A= 6dB and A I 0 dB g ive the results shown in Figs. 6 and 7 ,respectively. These computer simulation results suggest that as

the ra in attenuation value increases, the ATPC loop might

F i g .3 . D y n a m i cb e h a v i o ro f t h ea v e r a g ep o w e ran dt r a n s m i t t e rg a i nf a c t o rf o rD T / T= 2 0 0

b e c o m el e s ss t a b l e

C . S e n s i t i v i t yt o c o - c h a n n e li n t e r f e r e n c eWe h a v e a l s o i n v e s t i g a t e dt h e e f f e c tof c o - c h a n n e l

i n t e r f e r e n c e( C C I )on t h ep e r f o r m a n c eof a n AT P C l o o p .T os t u d yt h i se f f e c t ,w e s e tt h ev a l u e sD T / T= 1 0 0 0 ,A = 6 d B ,a n d t h ec h a n n e l - t o - i n t e r f e r e n c er a t i oC / I( d B )t o i n f i n i t e( n oi n t e r f e r e n c e ) ,0 d B ( e q u a lp o w e r s )an d 6 d B . Simula t ionr e s u l t sa re s h o w ni nF i g .8 .B a s e don t h e s er e s u l t s ,w h i c ha p p l yt o o n e l i n kwitho n e ( u n c o r r e l a t e d )i n t e r f e r e r ,t h ee f f e c to f C C I

Fig. 4. Dynamic behavior of the average power and transmitter gain factor for

DT/T =500

------------- T------------ ------------------

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6/8

--------------------------r------------------------------------n-------------------

-~ --------- ---- - | - - - - - - - -------- ------ -- - - - - --

F i g .5 . D y n a m i cbehav io rof t h ea v e r a g ep o w e ra ndt r a n s m i t t e rg a i nf a c t o r f o rDT/T= 1 0 0 0

i sn e g l i g i b l es oa sl o n ga sC / I> 6 d B .

D . S e n s i t i v i t yt om u l t i p a t hc h a n n e l ' sr e l a t i v enotchd e p t hA l s os i m u l a t e dw a st h ee f f e c to f t h er e l a t i v en o t c hd e p t hi n

R u m m l e r ' sm u l t i p a t hm o d e lo n t h ep e r f or ma nc e o ft h eAT P Cl o o p .We f o u n dn o e v i d e n c eof v a r i a t i o ni n t h ee s t i m a t e dr e c e i v e dp o w e rf o rv a l u e su p t oB = 2 1 d B .

E . S e n s i t i v i t yt oAT P Cl o o pr e t u r nd e l a yA n o t h e rr e s u l tof our s t u d yi s t h eimpac to f t h eAT P Cl o o p

r e t u r nd e l a yo n t h ep e r f o r m a n c e .T h er e t u r nd e l a yt d i s t h er e s u l to f t h er e c e i v e ra n dt r a n s m i t t e ran tennass e p a r a t e db y ac e r t a i nf i x e dd i s t a n c ed . A s a n e x a m p l e ,f o rt h es y m b o lr a t ec o n s i d e r e di n t h i ss t ud y ( 2 4m i l l i o ns y m b o l sp e r s e c o n d ) ,ad i s t a n c eo f 5 0 k i l o m e t e r st r a n s l a t e si n t o a r e t u r nd e l a yo f t d

n r ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ M e a s u r e dxp oe

2 U -:

- -_- - - - - - - - - -- - - - - - - - - - - - - - - - -- - - - - - - - - - - - - - - - - - -- -- - - _ ____ _ - _ _ - _ _ - _ _ - - _ - - _ - - _ - - _ - - _ - - _

F i g .7 . D y n a m i cb e h a v i o ro f average power a n dt r a n s m i t t e rg a i nf a c t o rw i t hl o o ps a m p l i n gf a c t o rD T / T= 1 0 0 0a n dr a i na t t enua t ionv a l u eA o f 1 0 dB

F i g .6 . D y n a m i cbehav io rof a v e r a g ep o w e ran dt r a n s m i t t e rg a i nf a c t o rwithl o o ps a m p l i n gf a c t o rDT/T = 1 00 0 a ndr a in a t t e nu a t i onv a l u eA o f 6 dB

1 6 7m s e co r 4 0 0 0s y m b o l s .O u rs i m u l a t i o n sc o n f i r mt h a t ,i ng e n e r a l ,t h eAT P C l oo p - s a m p l i n gi n t e r v a lDT s h o u l dn o t b es m a l l e rt h a nt h er e t u r nd e l a yt d .O t h e r w i s e ,t h el o o pb e c o m e su n s t a b l ei n a m a n n e rs i m i l a rt o t h a ts h o w ne a r l i e rf o rv e r ys m a l l v a l u e so f t h el oop - samp l i n gi n t e r v a lD T .F i g s .9 a n d 1 0i l l u s t r a t et h ep r o b l e mwitht h ev a l u eDT/T = 5 0 0i n a 2 0 Kml o n gl i n kf o rw h i c ht h en o r m a l i z e dr e t u r nd e l a yv a l u ei s g i v e nb yt d / T= 1 6 0 0 .

O u r a n a l y s i sof a n AT P C - a i d e dFWS l i n kr e v e a l s tf o l l o w i n g :

1 )S e n s i t i v i t yt o s am p l i n gr a t ea n dr e t u r nd e l a y :T h es amp l ingi n t e r v a lof t h eAT P C l o o ps h o u l db e a t l e a s te q u a lt o t h el e n g t hof t h eimpulser e s p o n s eo f t h ea v e r a g i n gf i l t e r( u s e dt oe s t i m a t ep o w e ra tt h er e c e i v e r )p l u st h er e t u r nd e l a y .F a i l u r et os a t i s f yt h i sr e q u i r e m e n tr e s u l t si n u n d e s i r a b l eo s c i l l a t i o n si nt r a n s m i t t e dp o w e ran dp o s s i b l el o s sof t h el i n k .2 ) S e n s i t i v i t yt o r a i na t t e n u a t i o n :T h el a r g e rt h ea t t e n u a t i

c a u s e db y r a i n ,t h eg r e a t e rt h ep o s s i b i l i t yt h a tt h eAT P Cl o o pw i l lb e c o m eu n s t a b l e .T h i si s s u ec a n b e s o l v e du s i n gas u f f i c i e n t l yl o wsampl ingr a t ei nt h el o o p .3 ) S e n s i t i v i t yt o c o - c h a n n e li n t e r f e r e n c e :O u r s i m u l a t i

r e s u l t ss u g g e s tt h a tt h eAT P C l o o pi s i n s e n s i t i v et o CCI a sl o n ga st h a tt h ec a r r i e r - t o - i n t e r f e r e n c er a t i os a t i s f i e sC / I> 6 d B

4 )S e n s i t i v i t yt om u l t i p a t hc o n d i t i o n s :T h es i m u l a t i o n ss h o wn o s e n s i t i v i t yof t h eAT P C l o o pt o t h em u l t i p a t hc h a n n e lr e l a t i v en o t c hd e p t h .

V . CONCLUSIONSAND OBSERVATIONS

A c o m p u t e rm o d e l h as b e e n b u i l t t h a t i n c o r p o r am u l t i p a t he f f e c t si n a f i x e dw i r e l e s sl i n ku s i n ga s t a n d a rR u m m l e r ' sm o d e l . T h i sa l s oi n c l u d e sa n a d a p t i v el i n e a re q u a l i z e ru s i n gt h eL M Sa l g o r i t h man d a l l o w sus t o s t u d yp a r a m e t e rs e t t i n g sof AT P C l o o p s .I n ou r a n a l y s i s ,64-QAMs i g n a l sw e r ee m p l o y e d .H o w e v e r ,a n yo t h e rs i g n a lf o r m a tan d

I~


7/8

(b ) CI =6 dB

(c ) CI =0 dB

Fig. 8. Effect of CCI on estimated average p o w v e ru s i n g DT T 1000 andrain attenuation value A =6 dB

constellation size can be easily incorpora ted .

An impor t an t f inding is that the s a m p l i n g interval of the

ATPC loop should be at l e a s t e q u a l to the l en g th of the

i m p u l s e response of the ave rag ing filter ( u sed to estimate

power at the receiver) plus the return delay. We have also

found that an ATPC loop is insensitive to CCI provided that

the value of the carrier-to-interference r a t i o ( C / I )is at l e a s tequa l to 6 dB.

An ATPC loop is also insensitive to the m u l t i p a t h channel's

relative notch depth . Based on the s tudy and results reported in

t h i s paper, the fol lowing impor t an t recommendationscan

bemade: For f r e q u e n c y coordination purposes, mixed

d e p l o y m e n t s (non-ATPC and ATPC) should be avoided. Full

pa th clearance (0 .6 of the first Fresnel zone for the worst

month) must exist over an ATPC transmission path .

Careful calibration of antennas and amplifiers should a l w a y s

be required. ATPC power should not remain at the maximum

level for mor e than certain amount of time. An ATPC system

should not use b it error rate as a metric equivalent to average

received power

Fig. 9. Power difference ( I - P [ n ]1 ) and power s tep DP, with DT T 500 andt d / T =1600

REFERENCES

[ 1 ] Retrieved from h t t p : H e n . w i k i p e d i a . o r g / w i k i / Tr a n s m i tPower -Control[ 2 ] FCC C h a p t e r 47 , Part 101: F i x e d A 7 V I i c r o w a v eServ ices , Sec. 101.3 , Oct.

1, 2002.

[ 3 ] FCC Part 78 , Revision to the Cable Television Relay Service (CARS)

( P ar t 7 8 ), Mar. 20 , 2001.

[ 4 ] FCC Part 7 4 . 6 3 6 , Oct. 1, 2003.

[ 5 ] C. Hardy an d G. Macey, "Changes A ff e c t i n g the Broadcast Auxil iary

S p e c t r u m : What you need to know," Commsearch R e p o r t , 2003.

Available at h t t p : H c o m m s e a r c h . c o m / .[ 6 ] MIicro-wave Fixed Services Frequency C o o r d i n a t i o n , The Australian

Communications and Media A u t h o r i t y, Spectrum P l a n n i n g Branch,

Spectrum E n g i n e e r i n g Sect ion , C a n b e r r a , Austra l ia , Aug. 2006.

[ 7 ] 02-146 ExParte FCC WTB, Cisco S y s t e m s , Inc., May 16 , 2003..

[ 8 ] "Candidate Standard: ATSC Automatic Transmitter Power Control

(ATPC) for the Data Return Link (DRL) S t a n d a r d " , ATSC, doc. ATSC

C S I T S G - 6 9 6 r 1 ,J u l y 20 , 2006[ 9 ] "Amendment of Part 2 of the Commission's Rules to Allocate Spectrum

Below 3 GHz for Mobile and Fixed Services to Suppor t the Introduction

of New Advanced Wireless Services, including Third Generation

Wireless S y s t e m s , " FCC FT Docket No. 00-258.

[10] "Fixed Radio S y s t e m s; M u l t ip oi n t e q u i p m e n t ; Radio equipment for use

in Multimedia Wireless Systems (MWS) in the band 40.5 GHz to 43.5

GHz," draft DENITMI-4097( 2 0 0 1 - 0 6 ) , ETSI, J u l y 2001[11] "Interference Relat ionships between P o i n t - t o - M u l t i p o i n t Stations at

about 28 GHz Authorized by Area L i c e n s e , " doc. IEEE 802.16. ic-

0 0 11 2 ,IEEE, June 2000.[12] J.R. N o r b u r y, "Towards the next generat ion LM DS systems

a r c h i t e c t u r e , " Te l e n o rR e ~ p o r tTe l e ~ k t r o n i k k1 . 2 0 0 0 , pp. 17-27. Availableat h t t p : / / w w w. t e l e n o r. c o m /

[13] "On the shar ing between point - to-point and p o i n t - t o - m u l t i p o i n t FS and

t r a n s m i t t i n g FSS earth station, GSO and non-GSO, in the 27.5-29.5

GHz b a n d , " Document 4 - 9 S / T E M P / 1 2 1 - E ,InternationalTelecommunications Union ( ITU) , Apri l 24 , 2002.

( a )No C C I .

-- -L

-- -

-- - 11 -7

-----

-----------------

-- -

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- - - - - - - - - - I

-- -


8/8

Fig. 10 . Average power P [ n ] and transmitter g a i n factor GT , with DT T 500a n d t d / T=1600

[ 1 4 ]" R e - e x a m in a ti o n o ft h ep r o t e c t i o nr equ i r emen t sf or t h eR a d i oA s t r o n o m yS e r v i c ei nl i g h tof t h eB r o a d b a n dF i x e dWi r e l e s sA c c e s sM u l t i m e d i aWi r e l e s sS y s t e m sp r o p o s e df o rt h e4 2 . 5- 4 3 . 5GHzf r e q u e n c yband , "T S LFina lR e p o r tRAIRAS-BFWAA n n e x e s ,T r a n s f i n i t eS y s t e m sL t d ,D e c .6 ,2 0 0 0 .

[ 1 5 ]" F i x e dP o i n t - t o - P o i n tR a d i oS e r v i c e swi thD i g i t a lM o d u l a t i o nOpera t i ngi nt h eF r e q u e n c yR a n g e s5 9 2 5t o 6 1 6 7 . 5 8MHz p a i r e dw i t h6 1 8 2 . 4 2t o 6 4 2 5MHz a n d6 4 2 5t o 6 7 6 0MHz p a i r e dw i th6 7 7 0t o 7 1 2 5M H z , "R e p o r tOf W4 5 ,Ofcom,U K ,M a r.2 0 0 6 .

[ 1 6 ]I E E ES t d .8 0 2 . 1 6 . 2 - 2 0 0 1 ,I E E E ,S e p .1 0 ,2 0 0 1 .[ 1 7 ]" I n t e r f e r e n c eP r o t e c t i o nC r i t e r i a .P h a s e1 - Compi l a t i onf r o mE x i s t i n g

S o u r c e s , "NTIAR e p o r t0 5 - 4 3 2 ,U . S .D e p t .o fC o m m e r c e ,O c t .2 0 0 5 .

[ 1 8 ]" A l l o c a t i o n san dS e r v i c eR u l e sf o rt h e7 1 - 7 6G H z ,8 1 - 8 6GH z an d92 -9 5 GHz B a n d s8 1 - 8 6GHz an d 9 2 - 9 5GHz B a n d s , "FC C WTD o c k e tN o .0 2 - 1 4 6 ,2 0 0 2 .

[ 1 9 ]D . B a c o n ," R a i nm o d e l l i n gf o rr a d i os y s t e mp l a n n i n g , "O f c o m ,U K ,i n :h t t p : / / w w w . o f c o m. o r g . u k / r e s e a r c h / t e c h n o l og y / o

[ 2 0 ]H . S a n d l e r ," P o w e rC o n t r o lA s s u m p t i o n sf o rC o e x is t en c e M o d el l ind o c u m e n tIEEE 802 . J6cc -99 /14 ,I E E E8 0 2 . 1 6B r o a d b a n dWire l e s sA c c e s sWo r k i n gG r o u p .

[ 2 1 ]"A R e v i e wof D o c u m e n tO D T R9 8 / 1 4' G u i d e l i n e sf o rAppl i can t sf o rP o i n tt o P o i n tR a d i oL i n kLicencesi n S p e c t r u mA b o v e1 GH z ' , " T h

O f f i c eo f t h eDi rec to rof Te l e c o m m u n i c a t i o n sR e g u l a t i o n ,D o c .No .O D T R0 0 / 9 3 ,Dubl in ,I r e l a n d ,D e c. 2 00 0 .[ 2 2 ]" P o i n tt o P o i n tR a d i oL i n k Licencesi n S p e ct ru m a bo ve1 GHz -

G u i d a n c eNote s , " D o c . ComReg 9 8 / 1 4 R 3 ,T h e C o m m i s s i o nf o rC o m m u n i c a t i o n sR e g u l a t i o n , D u b l i n ,I r e l a n d ,D e c .2 0 0 2 .

[ 2 3 ]" R e p o r tof t h e I n t e r f e r e n c eP r o t e c t i o nWo r k i n gG r o u p , "F e d e r a lC o m m u n i c a t i o n sC o mm i ss i on , S p e c t ru mP o l i c yTa s kF o r c e ,N o v. 1 5 ,2 0 0 2 .

[ 2 4 ]"Techn ica la n d O p e r a t i o n a lR e q u i r e m e n t sf o r LMCS," A p p e n d i xA,RABCF i x e dW i r e l e s sC o m m u n i c a t i o n sC o m mi t te e , D e c .8 ,2 0 0 0 .

[ 2 5 ]"ECCD e c i si o n o f1 8M a r c h2 0 0 5 o nt h euse of t h eb a n d2 7 . 5 - 2 9 . 5GH zb y t h eF i x e dS e r v i c ean d uncoord ina t edEar th s t a t i o n sof t h eF i x e d -S a t e l l i t eS e r v i c e( E a r t h - t o - s p a c e ) , "d o c .E C C / D E C / ( 0 5 ) 0 1 ,E u r o p e a nR a d i o c o m m u n i c a t i o n sC o m m i t t e e ,M a r.2 0 0 5 .

[ 2 6 ]S . A .C a l l a g h a n ,I . I n g l i s ,P . H a n s e l l ," I m p a c to f i n t r o d u c i n gA u t o m a t i cTransmi tP o w e rC o n t r o li n P - P F i x e dS e r v i c esys t emso p e r a t i n gi n

b an d s a b ov e1 3G H z , "O f c o mcont rac t8 3 0 0 0 0 0 5 9 ,F i n a lR e p o r t ,F e b .2 8 ,2 0 0 6 .[ 2 7 ]D . B a c o n ," R a i nM o d e l l i n gf o rr a d i os y s t e mp l a n n i n g , "Proc . of t h e

2 0 0 5R a i n m a pWo r k s h o p ,O x f o r d ,U K ,S e p t .2 0 0 5[ 2 8 ]W. D .R u mm le r , " M o r eo n t h eMul t ipa thF a d in g C h a n ne l , "IEEE T r a n s .

C o m m . ,v o l .C O M - 2 9 ,n o .3 ,p p .3 4 6 - 3 5 2 ,M a r.1 9 8 1[ 2 9 ]W. D .R u m m l e r ,R . P.Cout ts a nd M . L i n i g e r ," M u l t i p a t hFad ing

C h a n n e lM o d e l sf o rM i c r o w a v eD i g i t a lR a d i o , "I E E E C o m m .A M f a g . ,v o l .2 4 ,n o. l 1 ,p p .3 0 - 42 , No v.1 9 8 6

[ 3 0 ]M . C . J e r u c h i m ,P . B al ab an an dK . S .S h a n m u g a n ,Simu la t i onofC o m m u n i c a t i o nS y s t e m s ,2 n de d . ,K l u w e rAcademic ,New Yo r k ,NY ,2 0 0 0

[ 3 1 ]S . S a l a m a h ,Transmi tP o w e rCont ro li n F i x e dC e l l u l a rB r o a d b a n dW i r e l e s sS y s t e m s ,M . S .t h e s i s ,C a r l e t o nU n i ve r s i t y , O n t a r io ,Canada ,2 0 0 0

[ 3 2 ]M . C h e f f e n a ,L . E r l i n gB r a t en , T e r j eT j e l t aan d T . E k m a n ," Ti m ed y n a m i cc h a n n e lm o d e lf o rb r o a d b a n df i xe d w i re l e s saccesss y s t e m sProc . o f C O S T2 8 0Wo r k s h o po n P r o p a g a t i o nI m p a i r m e n tMit iga t i onf o r M i l l i m e t r eWave R a d i oS y s t e m s ,P r a g u e ,C h e c kR e p u b l i c ,June2 0 0 5

Automatic Transmit Power Control of a Digital Fixed Wireless Link

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