BSTJ 50: 4. April 1971: Estimated Outage in Long-Haul Radio Relay Systems with Protection Switching. (Chen, W.Y.S.)

12 MB·English

comes Aen

Estimated Ontage in Long-Taul Radio
Relay Systems with Protection Switching

by 8.8

HRY
(Moone cere Naver 24, 190)

4 generat ontage forma vesting @ swnbwr of impartont ater
tage factors hes been derived for Tong-hant rao reley ayeteme
ais iMcbond oF crossbow cvinnntie ehannel surtehing. This
foci ie aged to evtinate the atage of UD and TH systems wth
saris siting straerie.

he rests indie Tho the ovotsbend ® X 18 profectign-tonsnke
ing choanel etching system uppers te w very tractive aang
nent fro the standpcies of good system ralebily and eient nse
5} tho radio freee specter

In aver to gebieve tke hia oabis desnaed fo
ang. TH microwave io relay sistnns, Tmojuenay Esty Dy
tulnutie ehanne! ewithing i ueed ge am eBsotive mens lo protect
Serviees against oulager de to propagatir, equipment falc,
Tmaintensneo activite. tn this <erangement, acl radio rey rote is
Svdad nto a number of switebine sections. One ox two of the tnt)
ruulier aT rad chanorl in @ aves band ae designates as protee=
tion channels The automacie protetion eniteking system ust ju
tevtinn shane vo replace feed or otherwise uzavadlable reser
haele hy operating eithes TF or bazsnand switches at the trans.
Iuting and reeeiing cia of the enitening ection
‘The Zest prototion ssitoing spate. eevelopes for ace with the
ww Th-2 ystems /TNAS) cepaile of pace pte fee
le workin harels wits one povteetion ekenrel 11 % 8 smith
ig Ts es os in soe fy 18, atl Faron Zor bout
4 poner Fhe long-ha tain sce egoten nos ake Ho
‘Anocher feqceney divenity amicehicg system was veloped for ap=
eatin ta the GH ‘THI syetom hich mee oven on TD-2
14560 wm sretm auctions rocmNAL, arm 197

routes or used on sew rouse Twas iitelly insaed im 1960 and
forme about 10 pevent ef the emis mow eising in the eld. Thi
Fieeting sysere aaee Gen proleeson shonnels to proecl up to six
regilar shavnele (2 % 8 swilding)* Act 1900, the TD-2 radio
Toute eapacky was eqparded sp 1 totol of 12 ahacaals throug the
tre of ehunnele ioe fotersitaly tiwoen the eigical six ase
Inents, nd a aetirad nimefartee smicesing aymlenn sea nially se
‘tired ta provide protection for chest intertrial ehannels. A roach
tore reliable overll prolceian.ewi:ehingarrangomtent eoul be
fralie! by easing the raze wed the ifersiiel cheanoe into
‘eo protection and ten zogulir working channel aystem (2 >. 1b
ritouingh, ans cecordngly, the TNA protection switeing system
tree developed The LODA eystn wae otininal designed to oper:
‘nth Duth the exiting TD-2 eystem and the sew solid-state "TD-3
ote, Subsettiy, t wae modified ta provide 2 > 6 protection for
the TH system, Sines 1064, the 100A system fas Become the pe
inary heay-rouse prtastion feslity for the mierowave netsore in
ths county.

iach srlehing installarion 3 aox epereted exclusively ether in
the 08% ban (he TD sys) or in the 6-GHa nd (ihe TH
systera), and for ceaeave of rbablty, with the exemption 0” TDA’
theo protection ican ws tah bene esually ee specifi. Ts, x
fatal of four ebsance ev af 20 Tally Iaded route se reserve for
system protection use. Tn orGer to urea the troquoney pectin
ficiently, te tannhkr of yeotetion eheorele aoule be kept to
teinkmum eonsisten: with the syrlean roizemente om aelinbley. The
lasge-tale ure of coid-tate devs in TD-3 end TH-B unc higher
de muargina wow in Use sjscoms should result ieee system,
tutage” with provnt ewilehing wrangnwuts, This leads to rotueed
demand for proteetioa chanel qt the ohwereaton that © roduetion
inthe muroher of protection eanele mht be made possible by com
Wining 4 and GH in one enoesbund switching operation Deanne te
Fading cortlation ie eelativaly small between 4- and 6-GHs channels

Tn thie pape, otage ie estimated for systems sing various in-band
and erasband ivezsity sniteing arrungemnte. A geretal expretsion
for the ayetem oucage of a rorkice ehunre) ie Ot derived censder
ing the musier of ebsnmee, fading, equipment fli, waintonnee

Th mer, outa ceo wa i his Ce af ame
sage? tae sete tie gop Sains
TUN ete cue ner af poten sana [eee eq
Eisler te Bae nr re te wore ke
nonectioy sirncHNe syarEUs 157

and older autyge olor, The derived foraula is then applied to
Trrione TD ans TH syston rm ecinare the recht tbe achieve
by sutorotie chuoreevilching, Recon dbs of aetehing sta
egies exe sane, based on eosin wf elnbiee wo silison of
the sadio Frequency spce-ram

saa Sees Patna

‘The moet sesious source of wuts: esunntert in eurent 4+ and
6Glle micromave radio evsteme is eonsider Up be seletive Fading
fuer! Ty the multipath arerieign ss wietownve signals, The

auodlunszo and effets of mukipai trcasndsion have heen disuse
‘tite thoroughly in munerone ariel phed inthe past ta dee=
flea Selective aging is characterized by deep excursions of the
eovive iene signal Wve low i foe spor value: The tive
seule vers from n Few secede far lenge exeusions (uverege Murte
tion of 40-€B face! to a few aunded enene for ama.) entucsene
average dination o° WB fades). Tae diatibeon of fading vcrhe
Tine wh tine dgeds up vevaile of cemposasy sonivons io the
ewan fal in « emuples wanves. Engh daa nom exis 20
Support an erpiseal faman.a ylang tre mst sort paotees?
Casvetstion of a pertinent atl available selective fedicg date ix
eer lice es thas the fing ditvisutin cov single bap ie ear
tetrad hy a Aaa! slope of 10 6B of fade per dace of prebabilicy
for fal dps govater then 20s ithe slope but not necessarily
he angie of the Rayleigh striston, Kine tity a facing i
frequency aeleative, the use of ether frequency o> space divers
‘Wold be effective in recuing its ee: en outage

23 Plot Fading

In atdlton to selective fading. there exe opsasional long periods
of depnesed signal in a inivewave path cance iy "wart bulge” ar
bbstructive facing. This type of fang i rae att wuts ony der
substandard stimapheric canis Ts atene of zh soit cone

taal ee ask air enon my ae ding ve haw af ely
morning and ound fog ere vanelly poacueve ta Tak af this Spe,
‘Wieely separetedfoequeneion ann vewirally ate! wncerams ae

Tae em Vet e big edi hegencrl nes od hs man pp
1488 ames sveneae macusuesT FOmmNAL, arBaL i=)

too alike with regard lo Ue average signal love) (Ref. 6, pase

2). Therefore, protection ayainst fet sucka ean be acrplished

tly by pnovidingalaquate verte pall clesscnes end restieting the
gt of rai pache

‘a8 Renipmant Pature and Masntewenoe

lice seletive acing, the anlage Sus to equioment fee and
nninienane a of tolesivaly long araion, Most aieromere cio
lelions ate wusvanied, ard tkeofare, the dws tne of « chase
dhe to an equipment fadhine is longer thaw the sversge repair ine
tuvully use, Routine maintenance wba iveveass the bean of ut
fete bevase the mune of proton ebannel available ime system
is reduced when routine maintenance ix being dre on oxy oF the
thasne Ie fie Ie resognized that the equipment failures and
tmainteneae ean contral he sytem outages in x Tong-hsul system
faving only one protection channel? In Hie pus, Sahn frequency
tivereity wilt in procetion ohannels ae been use eMecively far
both fading ani caxipwent soleetion. Now selidvtate svieme are
fomsted to be raorezeliale than vecuumt tube wsters, Thus, lower
‘unmert outage niles woul I expested from che newer TD an
THA ayseme

4 FAS Terminal Failure ane Gtore

folkdestate 3 EM torical weipment togetaer with golidestate
38 wine Tine entrance fink coumprint tod the 2008 protection swish
ing eystern (2 1 > 12 datum tn TP syste) have bees introduc!
Fos tnanterance and hasebund view’ qatetion, Therefore, it ie ex
peste th (eset of ayetem outage etulting fon: terminal flares
Jill bo small” Ofer ayetm extge factors are power failure, oman
frror, anit switch ailnes? Those ottagrs oun be made small ine
Tengo spate

ere we devel & method for the eleulation of 4000-miletwe-
‘wey annual outhee relting rom th joint efces of sletive fading,
uipmest filer, and meintanssee fer a rasio ystam wil wil

THe ain oe FM vernal aes 208 wails ant
sn pe Ste FA fn essa we ln
ratic channel switching It noted tha, without protection exiting
fetes, the autage from the aforomensone factors ine 40N-mTe
owe wld be several bunsie (about 8 in the 2% 10 TD-2 eye
fan} ines the foal oslage oi thr spew wh protestion switching
‘Thus, these three fac‘ s1e smog she must impron: in the eon
dsncom af rye tlinaity,

i Aciapticns

“The basis of any estimation ofthe eebibiity of system i wmstie=
smatical mode of tht system. Astumprions wee mde as tothe bchavior
ff thi mae! whieh we ext wi give che medel the eitributes of
Ue working eter, The following weave weer made in che ey
of rac evevetn reliability

#11 Faatng ond Pating Rrequeney Coreation

Fang rates ane based asthe MIDAS 1996 West Vnity data * These
fata, shown for a BS-l6y cummer period (uly 22 to September 25
1} se piven in Fig, 1. The average fading vate shown inthe figure
rerun he percent probally wf Ube sigan” ing Taled ta acer
in qrh for preat=: lave to fre spuer for Uhe ral Hie af 68
Anya, Vang vera (reqeney corelainn basil on om expicien)
focnalacdveleped hy W.. Boone

a Fading A

iy
Feing ie aceumed to occur only during s rs-hour pesos per day.
‘Ths iss zeteonanle assumption over the fade depth of 26-40 als
and is supported by the Bryon-Wanseon data.” Figure 2 shows the
aio of fang rtes during the midnight ta A.M. period of mearare-
rent divided by that observed during the § PM. co midnight pried
Fing sctivity was nealigible dus the remsining times

tk Fating Sita

Cntage resulting from simultaseons feng activity in iferent. haps
im te sane enitesing setian is raleutaled a a daily basin: Daily
Sing suce aeons ae evans giver. a Fig 3°

ne Fating Hope
Feing i esumed co goer in ery ane hal af #86 hops,

15 Arua Paring Distion

leary fading is estomed to oeeur for two monthe, medism fading
Moo Tw ey svsuat vSrAITON, FOUR, APRIL so

frater reduced by 1/2) for two months, ad nesisible fading
evn for the raining eight months of the yea

08 Switeing Syeta Operation
"To simp'ty the coxpusntion, che ewitehing eystom Se asmamed
biave no Estee, tha ny uo wicker chrosbodl nthe “chan
goo" sorats "chem bi” sewison maker «Taitatur) en no f=
ferestition beeneon rogear ad polelian change with ergund ta
the gach point, Tis alo geen “hat the saz poixe fede éeptb
{whieh proteofinn site ie eauedie) is equal tothe fede margin,

sur Joint Fading and Mosutononen
Pea stivity ond meinenance aeivity are assumed Yo be te
tually extsive a6 resi of maintenance rues

TTT pevent

ie, Avene fling nts of & AME, shane Sed tee BOA
we UM GM Sl SS
Parrycnos swears svete ust

ig. Ratio of Gliese Beas Wao de

sa Maintenance

"The mainteranoe sate fo slid state sqviprant fs agmmmed éo‘he
Ihe seine we fon TD-2, be, 4-1/2 hours pee yone pee T/R hay (1/2
sows por T/T. bay ot four-month itervale). Mlsttenance ie wast
tebe coworntealed curng w six-hour period per dey

519 Eouipmont Paiwe

"The (lure nate for she soliestate repeater i asune to be ULE
feitre per T/T bay per mons. Tain reese wu $n 1 improv
nent over prceon: Facnur: tie TB reniwrent feiane res, The
fasuns wie of TD? ie ectmaced at ono per T/T hay every two
sours end the average cise to rep sm eupsnent fellure He sa
‘ed to be 21/4 hours.” This enerespenls to ectional outege rate
Ine vem tube T/R bay of O.NtS prevent, The solide sate i
taken to be 00048 press

autay uo Consents on Meivennnce Operation
1 Muintencace is x2t o be undevtskee gn one ehonnel hile any
other cheno i 35 same awe series hae un equigmert fale

in she average sine seed ta vcore chat uader susie
2 nee amt syoues

(6) Tw the event of an equipment failure ox any ier channel while
alntenarce ie in profes, he ehannel inder nmintenance will be
Festonal to servi within «shor speifiedincerval fay, 10 rainuie}.

susat Diario of Soitoning Ration Lengths

‘The silcbing section Jeng? distention 3 aeesinel a8 nosed
by Hoe 4, This siotribation ie Inaed onthe reels of » 3862 TD-2
survey with Ue exertion taut aU persent of the exe-aap switehing
Sections wore deleted to compensa Tor the nimiber of exe-op mess
age il. yt found im a nin role, The eeslte of w 1967 TD-2
ftrvey (with AD percent ofthe te-ho sections delet) eubstantally
Saroe wilh Ue assumed disteision

susie Repeter Spacing

‘The wowrage repeater vpn is asmned to 2 27 aales. This is
hosed! ou TD-2 mite date e¢ of BBI-8S indicating en avorage hop
lenath of 2665 wiles

2 The Weiphol Average Outage
Consider mnlteksanel rwlio relay anitehing section having»
shannels of whith {ve 1) age protachon chapnal. Ac Jost ay exo

ig, 2 Daily fing ste be a the Byam daa
Puoreenion swrremine s¥siiate 1483

Bie, Serie abate of eaetoe scion baglhy asd, fe
se SCs Ege i tes ES pe aS

‘enews fires oF intecruptions axe zequie! before ther i an aetual
‘iloze oF loss of servi Thse outages enteesoniing to move the
fue lane Falls should se wengted in tae eyatam

Uulage amputations ence, for axaivoly, the evene cf to Maen
thhozes felled ned wnowetorstsimulaseacly ie nbviniely Unie ae
serious ue the event of ane waving elnnel fai al napeetecied
St atime in given ayster. This, we may seine the weighted arer=

age outnge of working shane! a Fellows
‘bor = the weighed average outage of & working channel,
[tae expert mnesber of working ceases f

ad not pinot et Lime
total numberof wurksxg

“Bxpresced in probability notation, we have

an eth

GEM Comey ims Da

where Prexatly Gn +) the prbabity af exactly Go + jh eb
ling Fe szultoreonaly is «gon seen,

8 Devvatin ofthe Weipa? Aswnge Untage Pont a Suiting Sesion
Let i now eorpiie tae weighted average outage frome svatehing
section based en ration (1). Refeving to 2g. he sihing sees
04