NASA Technical Reports Server (NTRS) 20040112054: Erlang B/C Link Availability/Blockage for Data and Voice over VDL Mode 3

0.4 MB·English

by  NASA Technical Reports Server (NTRS)

ERLANG Ti

LIMS AVAILATILUTY/BLOCKAGE FOR DATS AND YOICE OVER

WDL MODE 3

Mobmmed A, Shanumo, Mubunongils Shainama Gore nasa wis, 2004332018
Aualex Corporation @ NASA Glenn Research Center

21000 Brooks

Abstract
Thar analy bole nun te btekage and
nail gf Digi? VE Made 3 link tine
fos: prvi ice at CPOLE tats tas
(ond the Evlang Bnd Pang (formas were
vised to monsre the wil
the 140 appteatims over FDL Mode 3. The
rsdhs here alone itt pietnae ell copacit
‘uleaton on he ber of regen cates
atlbls dane ae prt of parse sey, can give
@ongeure of the cian draeal yon
apacit Thar sate omy ener ovate
for eccspsble Biosage teeh fr wien cose
ages toate Mis foal thes over the voice
commeacctions "wi ratios Bat pao
hemos followed by de Masagemet
ceensog portion ofthe dt oc orn
ey CPDLC capabiig: The mow safe
reducnon of tea! maxex eapac f probate
1s inti of he wor ie hance ab
1 hanile a tage group af avenge wihin 2
secon. ARO U1 fad las reine ot @
Supls weg chanel wt sacl 23 Mbp
Besneney anne, und nepring wack conratr

So howe 9 sigle woe chet Hn the a
capability considerably men for 3 wee, fa
ved conbgwrion

Introduction

berscen pilots aad. cont
using she analog VHP Voi
TAA 1] is planing wi the isp of od
goverment aul incusiry partons isoci as
NASA [2)) co modesaize the aie space ane
fnreluce digital und networking technologies
‘dat will HelgaBleute neny of ete capaci
ara deley probleme nocuaing in aur present
system, Evory year appromimctely 400 now
Irequency sbomnsls havo wo be artigned eo

1k Row, Cleveland, Dhio, US

that to aecertunadate the growth ef the ait
ffs A} AL Saat vel eke
(apesbchihately 46 zoury), is expected tet
he system weil asch Hes serting

by a cocads time fue heme making Ur
coleenizaion afer? a emeial one. A ses
boar inpestamt part of tis etfor ia the
inerodustion of the Very Eli

Dighal Link (VDL Made 3 10 rephipe the

TATR) data sant digit Hui in
replaces 2 single 25 KHe channel wit fone
Jogical Inlepente chunrels wth cae. ved

F vcien or data taster Among
uppheatiens chat will be guppoited by ie
YDL Mode 3 link will te in addition 1
digital vee. the Contre Por ars Line
Commanicaions C27DLC walRe. CPDL
suppars efficlem Clearances, Plight Plan
Mocafiwions, an Advisories nealing
Thazardous Weuther Alans)

Aithergh the VOL Made § munduesin
‘wll ineresse cae available atin! sys

opacity Jom 140 19 four doves thar of tle
aualog system depending ent the
Cantigwatioa used. it is Tound in previoas
snudiog that such ab Lneease ig sll nek
sulficiet at contain skinides aud in verti sit
apeve secznes fl]. Nowrheloss this 5 gly
(ur if euch user o:cupiss the allocated
TIIMA slot forthe entre Dight which is

expected to be che care. Thig akon ely
ilemp to unaytiully teesure the nome
‘usar thal ows shave at siag’e TDMA let
given the anplicmions lsing Ged uae Ute
Tinks sud the decsity of the aie pace. The
ese of the Bulag B aed Heng € is sited
Tar that purpose Koeping ia mie several
vwrables. the next fone sostions Will cover
Ue CPILG, veiee, and VE 3 spoefictions,

hia prt oe rin at 2 pana intr for prosaniton at @
confetenae, Because changes may 9 mats belore Ferma
publesten, eiamede aap win the ge laren Ina
{ese cid orapracuoaaanhout he pernicslen che utr
the Prlang 4 Etlang. C2 computations, the

ols of wwuilbbdity and Blaeage, ard the
Voice and CPDLC upplications
on VDL Mode 3

The VDL Molle 3 line gural
specifications ate show ig Table L [ST
tess Time Division“ Multgl> Avon
(TDMA), Ty dive up the 25 kth channel
over 23 or 4 vss Up to seven
onfguruues nf vice and date sherice uc
fined, YD Mede 3 uses a Di leental 8
Pine? Shift Keying (D&PSK} -nadutocon
sohomsata daca eto of 315 sp,

CRDLC inthe designatod data
application to be utilized with Oe VDT. 3
‘iyi lds, This isin adi.Jou w the voice
copanitiy. The voice conumalcatians «ill
igenera.y vccupy a sngie TOMA slot forthe
Gnw the veive coumumecucss is meee
pic, Tao deca co the lee Teed will
fusupy a gisen number oF TDMA sles. tha
tae sufcienl ts send the dats packers, aad
hen gite way “or other user dato packsts or
same, sar ar packets

‘The CPDL application funue puedicied
relic iad x nhtuinee from [6], and fm
(7). Compared to ater serenaptical
‘pplicalioas (aot plauaed to yu on VIL
‘Meds 3 link) the CPDLC data ual is on
the law side CPDTC messages ue
pesferiatel apd wil be used oaly of nseded
bases by piles tnd emule 10
communicare "ficient Clearances, “Tight
Bln Weaiieniors, and Adviaeties
Gacludigg Harclous Weethor Alene}. “AS
such rors toescages wre eapocted ne aireeath
ame closer to the atpee! area har. Ea Ko

The wice cxramenicscions willbe
necacsuy a8 well a8 Seu although data isthe
prsfershle mais of pilot to cautaller
commaricatins es iis bec oprimzed wilh
vse cf CPDL,

VaFeeg ar 70S Beal
Seen) ocaey tt Uy
Taba TDT | Te aR

STOMAcae | ST?

2 vice
rue. dee

tke sunigucuinst
vaca we

bead

TERM Drs ara a
tome) ur lates, Luge te aiag ar
tt soniye

TSE nee“ 325 Rh

‘ete, i

VSL. ova de’ | TR

| su mince

FAT

TDMA sou wi. 1 pron

us per TDMA 3

[nates 4 ti er Feara)
Tian iimae
har DME eat

Seve deaa [peveara
edi resergs

yer TAMA le

aST5/12064.8 Ki f

five TOA al
3 eet dad

Tose Tene | 10 ane
paws
Aiphine 10 Wate

Tratsail pres

Tare Sea | UES ae mam may

wCo-cbumne:
idan rai

C300 Time [Tang rate weage ot SOT
‘Site pore

nd dle

ie vate fo

aoe Tomine al Noa

5s meas pet

“Table 1: VDL 3 System avd application

arumelers
Voive sill be used far fmctiont aut
covered hy Ye CPPH.C or by eer dete srv.c88
not using VOL Mod2 3. The talc Lud Soe the
vyoive sboven ia Table 2 vas eine stagiced bom
te

Tar CPDL Cael

ie appieeta
} tdataand ice)

MWbisesipacestre on |
Saamennewsspe |

Osetned fom _ | i
[al bs 2D Khivesipe onc, oF
brnjee oigs S001 Rb ps

toa sozatl

12 Kota pie oF
(BiB? GAH Khe

Aiscralt Wook
‘ante nds for
peor 2015 for
AML clases
Gav emes |
Aesignated

i sect)

192 ieee or
sicpoce

Lb a ate uk or
Lust = 0? ies pe
saat,

13h Rae deci
X5t irate ow | 13.600 9a a per

ecu tin,
‘00 alreeu for | tga Yate:
Enea

2.0 sept epnk
PV ea SIDE Roig at,

(36402 CeO Klin pr
dios

42% be eri lao
Chiara aaneb ese peso
deed over

Qonunote | 43% a cin oma, ot
Feros | haat = 28 ester persone

seconds), wate | 1036 KhiwsFm Row opi ot

Ceruole is | W5e0> cued hte pe
uti over a “| eu

Stnimcte | 2 pie En-Ret olin
Sandon. 2 SED = DGKS Kates

‘Table 2: CPULG aaa Voice Fare Trafic Lauds

Fer foth volo: sed daw cia
rvjecleé pen ie walle decaiey wan ured in [6]
wih sarin menage Inks asdf
deponding en the alspace >
‘The peak taf (sing UB minute vital) a
the Wasat sigpon as quoted as 192 a
while ut arena i was 157 aiovai,
busiest in Rous aestcr msg 50 reiuates
syingow it was 300. he vo
in €] by eal vs9g2 tie over ebyerea ion time
und seas comeitd fo this paper to Xbis!s usi-e
hive Veewcer assumption. Note the
WDLUTDMA service rle as deslaned 10
that a8 Rbitslaee Veooderspeviition.

‘me VOL muds 3 will wie within each
‘TDMA time slat, 2 uesugeneat portion where
the sterats will be sending segues dale
rmeseages. ‘The service rate af zequest date
processing cot rage fem 02 Kbtssce up 19 2
Xbjfsec depeadiny wn the numbor sf M sles
(cach slots sarice uate is 0.2 Koil}. The
Toquest rsstago sizes axe only 43 bis each, a
it was ugsumed thst dhs Boguoney” of the
amescages is eyuivalen us the Fecueeey’ af the
EODLE mecingas (ol woiee to = leeser ont
houge not ircluced) ia the downlink dieeetiv
Only cownliak requests for Give sate oe
row he azerft uo the giound, Aeorever, far
every uptink ODL menage Brom. Lae ground,
the aircraft navayertyrolovel liye sea bo seu
aa wckoawredlgrent, and to da that it eds (0
Sead a mquest Fur atime alse, hence adding to
the frequency of veuired cajuesl. AS such a
reasonahle hequeney cat be obtained by sips
lukirg ike combined doom Esk aad upline
CODEC dia race in each dnvvuir, and dividing
by 8500 bit CDLC average packer size (For 4
simsareacive Fosulj. Ver axacale in fie e4
rule, we woud have
WOR HANGIN — CPOE
Imessagas por secon, Thewe om a sverige
bises we Would have a Least (M6 req
fwenaages per econ par ataraft. sing che 44
Tit regued rvessnge sive chs gives usa mio ot
INVENATAAATOR bitetive. —— Siailacy ths
request bivsee rates fort athee dovaains can his
cue puted sud Table 3 suuunaies it
[Seveetea ae
Fee eaves,

2 Beasel
th p29 1091 hats i
esp fie IT sification
and 08 de“ 202
aeaneeampl

rmossages Ber
bare la

[ati

TRegestaaaae | Aisi dome

jedi rincia he | 3.LIE8 Bien per i
Sans

‘eaction

Tera msn
149 Besee po aca

a Rous dain 1
(.26¢4 susees per area

‘Table 3: VDL, mode 3 managment tinal
(gosson of eae TOMA tue 00, and ae
request issngts de tad Ue tes

Erlang B cand Erlang ©
computations of Availability

Given tue ype of application, andthe
formation in ths. prawns secon cn the
sq eign demeaé rile. the ainpave d

and the TDMA slo, deh ran aj
pposabls eo compare the availubiity of the
‘vimmunicution Bak per TOMA digital cxannel
(er son). To da th to Formalae ave usd Ue
first is for fae Fea B and ue socom is the
Evlang C. “The Belg B acmouies tha a reqeast
for ctrvive mnt be serviced Irmmcdiatey or else
‘Sropped “romediaely. the Krisag B formu
(hsed om an MEMS Toes ayslem’ gives che
prubobiiry Mar a new block te denied ea
alse au buffering capability, "The farmula

ven by IS: a
Deoat =| 2;
or

~ wo

Whore ois detined ex the anorage trati
imensicy im Belang gitea by the rio of Ce
average service demand rate 2 is bisieecond,
wel the average use link te" ee ia
bbtstescard Nae his ie so called ered Ton

‘The Drkng Con che od
fon ca indivte quese MiB 3p
Frlang C, also called Trang dolay tecmzia gives
Le prnbahiley chat @ custaces (or diss cker
for dala services) sing et My Ce pplication,
wwonle he mira to queue far eervce, This
Ep sume a8 the prehalsliy ait ts

ears custemore (data patkels) ia the sete
ACroaly by the tie the gant packet aetives. The
ovmula tor the Elang Cand fs veriatins ahs
ivan Cy [8h

a
1
6

Wew, +, a

W,)=1-Cledaxpe ? «

jazen

jp. CAE gen LEA gerne

irel-e) teria

1-C#Ete aye) eps

Wala) =1-Clena
ao
were the parumetes Ta:8'q cceresgcad co the
mean quene si in gaskets, and rasar woking
time im gions. in secceds Siifaly Ws
wermespunds tothe mon 41vi0e dene, ile W
eorweponls to the mean system time (oevice
sd quaee). Wa) cad WU vomeapond co the
qucusing time clericion, ane the system
waiting tine distdbutions respectively. Filly
rar ecssespud w the c™ pecan detuy in the
boos. A formeuls “also existe for the
Sock y trom the
dion inte weicng tnt disuibucion Wi.

“the availability ie ganorMly deta oe the
probabil chat ch at least ens eiety TDMA
slots is availble when a packet 's Feady to be
ot» which is vs uf ke prvaeneaes of rest
For dhs Erling 6, and Erlang C ecimputtoes, i
in ger. by the net to ecuatons:

ay SI Besa)
A,=1-Clea)

A variation’ ur the Belang © sein chis
sds. Here. de avalabiily is defined in terme
oF au avcoptable maxima waiting time in the
sysrem (Outage devintion ine Ty) beyond
which a puck: fz deemed wentlate. 1 thal
ave and reginélec if the > chance are “al o¢
sal, iUwou be sya to the probability thar 2
has to ea in the sysican or Conger ex

autage defistiar time, viel i ualy
fv uke data lyse (ab ope st the

Ag IHW T g) a3

1g 3 compwrations ane more
eprops for che voics wplieaian lacs uzere
sil fe Sharing le ovale sunames in pasty
Tite scenario snd cals do not ave the wing
ception at the data as. ls the chanel
And soquest 0 tap slts is Best analyeed with
ie Erlang H as will Ae explatned taro

‘The Trleng Ci ane its wedaron ae -inoee
aepeapive fhe fe day CPDILC yppceetion
since it allows tor qoeuing. Te aseuenption that
ere ae an infinite sizs queve i seceplsble
since there is ploy of cupabilsy on Sad The
sivnfis, amd oa groimd w sore CPDLC
messages aml they ae dus tte seul, Hou ie
taller tia? a yzeue limit has 1 56 impossd
which Js sumll below 10 CRILC trames fir
example, which is hehy oalels). es ¢ nore
"gprapmace rade orn be es MWK, ‘That
eu 3 50 tested allhough 4 as I thal
nore amodel is anoce apprcora

observed using ths MES
pel inc us the waiting time F964 and ia
the syste, 8 vellas De

Ir cats stly, che avallabigy is oumpued

Indeperstenlly for woiec, date uc ding
CODLC, ant Muragemeat meuerr. Ne

ditferect svailblity Hames (ober th ws
afscuss the limiizg freors of oae te he otk.
This was mainly becaese no ~

only aveable i ta sustest
Serwad tnve bereticial to sandy each ad en te
them all-eagerter. None the Iris. if a stir
vembinuton is needed thon » madplieaion of
al versione can Deconeiered sick a

Foden asi

Availability and blockage results

Malong use of the lormulus in Le previnus
stot, bd he irput dite of Table 12. end 3,
‘yo caa comnpure the avalabigy (ce ockage) of
the wbiee and CPDE.C application in vp and
Govenliok ctions and aver the thine di¥e"st
sispaces,aicpet tui, xd Ba Ra

‘The cies applieuion used the Ba
orauile size vale els ae no seus’, and re
ctfeedsely cropped if no channel is avslabl
Th resus forthe woe ste show. Figule 1
Tare ence the yi and dowalink will he
sburiagtis sams channels, the (wo are nabiaed
Combining the

She dsm

races in the to direeions,

Since vss cnnmollsr will be auuaging 4
Single, sector with each sector covered 2F a
Slagle voice ecu it was interesting te Lank at
the: avaiahiiny in renms of single voice
chnunel (onl). Higuce 1 epasents Dut ease,
‘The reitionship isnot linsar and he v2 ean uel
De wurly deduced fapnsFigure 1 direty

Piguee 15a eilbity oF voice sursees for arange
cof data fae asing Enang # usiag w single TOMA
ior ol,

‘rom Figure at cam he seen that Kitts:
vyeize digital load is suppored wih » grade 0°
servis of approsimstoly U.S. TP such a grade
af wice servioe is acceptatio hen 2 site
TDMA slat cau suppert up to 6, 14, ext 37
aipeats fo she aiport. weminal. end er route
demain respectively. IF op the other hand
grade uf service Bf DD ig ncevied then aloee
umnbess ave uppresimacly reduced in half to 3,
3, and-I8 tetpecively, IE for the wake

experimenting with having 2 chaanels availble
(© sbue, which sana 2 contre
auecommodating the same pool of averats (on
nlkey atenaric, i eau De sea Esta fou us
Bit tines !mprwerow#s aghioved 2a thet case
For example for Uie“OBE gues af servis

approniuslely 34, 56 and 119 atrratis ave
sugprrisd fer signa ler, amd oe ree
demain: romentivaiy while the 3 gre of
serve of 08 at least 16.42, ane 11" cae I
sayy Haviag 2 valve channels
Indeperdensly fone For comusles” foe ansh
ester) weLld Sacply provid 2 Hee that of he
single channel aud hence less them Unet hy the
sharing seeatie.

Next. iuvosigating the dls sersiews af the
CPDLC. ever the ¥DL Mode 3k, ne used rhe
Avila fy ds weedy coneeponding ea the
waiting time distutign is he syste This i
dene Iw awasuie tbe 95% prukubiity thse 4
CFDLC deen message Would sellin tts ojstem.
quewing. as ll as tnnes) sven by
quan J. Ve requiem 3 pivod ca be a8
"095 probably that a high prinety message of
182 is to be delivered within L second [ST
Figure 2 shows the system wating distribution
ower a ¥ mcond window Zor data loads esaging
feam OA up o 4 Kbitstiee using a Gat Kbsee
Tuereneal Allkuusls the esquire:

ream af 4 WLI CPDI-C esa,
size mzazige war ued in Figs 2 for & nore
genes] cave, ‘Te 192 bat ons woeld provide
fven better see

Figure 2: Spstes vung time ditibatiun carver
‘Wop for a sogle daa sit qharme! (20, wilh
EPDLE Kram sizeof $00 hits, weog a range of
faa rate starting Crow 14 Ktibisee wp to 4
‘isbee. Boch geaph Inerusicnts tm evder BF &
(ol Kinser se
2 ndicaues shot a

data Joads vp co GH.d-2.4 Kbstsene(eeth ure
fom Jef ta righ}. As wich using the 24
Ebittiec. snd the uplizk and dwn ds
vatse per aisenfl shown is Table 2, te ca
‘an idea

sb. For exuniple a
cortesponls 1 2aigLOITTANOLSL
aires, while for teeuial 1.8
220.009 WLUKI)=14D eieret, and Sully
for en swe it i LAMOONDRUONRO=LD
altemtts, Using a 129 bil amaze size 8e got
4, 98 aed 657 aloias fue e-pon, tems
and on route respectively soot tbat the 0.98
prububiliy fs met. Using moce daa ehumel
Such af (0 ay Hee (622, 23} impress
Tvmsers amnscerasly and wis obsiousl
beyond the need of the cepabilly oft
cuubller provseing to be sort “while 1
invetigate: See Lee. us will be pintado
roxt. the ascersing don vin sho Mao.ger
burs within the M portca of Nhe TDMA slo
line dee vayzuhy eoesideramy <n Looking a
2, an c=3 cen give ay idea vf the comparison,
petworn He THO ANE tere Ine weal
‘cont gurations sheuld nd am be

To study she aoecasing or maragement
portion, we ulilize the dus in Tabl> 3. Since
management chainsl3 are itbedéed witkin
TDMA slots with up to 10 anahlle depelig
uu te couliguraiua. we fst Leo at he
capably ofa single one. Au Mbt ows mest
is best auitod co appraniiae royueel Rexwsior
since rquest packets gor fot when Ley callie,
Als since the assign of 1 ML bust sla
lone ac radon ftaitoeny) whan wircrats wis,
catemamt, sling move Bl slots does cat meth
ep with aging more ¢ cxsunels in the MIMIC
sg eeodel. Ruther, because of the sudo
assignee 10 the Mf slus, Ue sysser weld
Toole reste Tike.9 cSt oF MEHL Le awadels ia
‘number of eile Mt
Sluts. Thies Sra ack in sera of capacity a
‘ding moiz ckannaly to at MM Joes syetom
(le. 6 being equal to th etascls avilable)

‘won gordve w meh larger eget tha 3s
ofc MIT loss sales in parilll. |The
obvious ssazan for that & Deine he Ee
Tees ince (as wel a all acer qnovisg dels
in geal) ascares thar rem packsts go hy Ge
empry asiveis (# uyuune W ksaloney geuing
aasighal ts a weer which could > iD 032 ot
ot}, aud heace a imucl mre spe usage ©
the keris eapabilty is dete ial wi. ane
te eas, wwe are limited 19 the MIRE loos
perallel case, aad we etimace eupaciey of rare
thun one KE slots by sixcply muliphyigs
resulls of the MeM/L Ioge syste ith he
suutzer of aa ble M sens. Note this isnot Ee
case wil. the duty ponion of the CPULC
araiysss. since thers be graund_intllgen
hes dite ct into empry TOMA stots when
sisilible and Eence an BUBGe model iz veo
dealisie (38 oppove to © MALL modele in
pera). Figure 3 neal clone the expucily of
Hogls M slo: given a tangs of data lsade {or 2
Agia the Teka 18 is spprepriate with a sight
Face Feud etal sytem du Ua aok
repeued caquests when a cllls. an accuse wish

fiferoace bu: not a5
sSgedficut wu waran Fae usc of a mesh wore
cerstounzed syseue for Srl sud.

Figure & Avatleiluy of the Mupigement ebauncl
(a portion ofa single TDMA slo0 for 2 rage of
ust messes data cates 3usng Hllang 3 and
a stugle BT tine lot OM chumet) wilh WO
[BblUyes ehuone! service rate
rom Kigne 3, we car xmsluds ther fre a
single MC chisnel, 3 ean have up fo € wera

(10 iteect sccormndated fa ln teraucal
domain at 21.95 graleof service cor 5% chacee
of beizg blocked or colisings, Smitty tordl

095 gre of service op te 3 almonds can be
seeommiadat in the simport dota, aed 2. in
ie en route demain TE we use. D8 grads of
service ie tke numburs approximately double
W612, aad 42 uicras fo the alepat ena,
fé 20 roUne douains resposs

sch group (or single eonrollr group ill have
1 ¥0.ce and 1 cata viannels (1 3MA slots) wii
veh coming an M burst Tssical awash,
Hence for a 0. erade.oF sevice te eovassing
‘Ube Himited to > tess the mnnabecs in Figure
3, ot Basic My 12, 24, und Ba aireras toe
leper, minal, and an woule demain. In the
‘31 configucrtion we have up to 1D chan

‘whic Teuls to 60, 120, and 430 sims fez a
9 pond of verve smd 34, 60 and 21 harrahs

of wervive in the

em coats Zens eespee
Based ou cose sesuts it ie evicont that the
capbitics of the axa sevices ume Fmited by
the acecss chars eather thin by the (20K.
data pustions. ‘Thnwe rests wove aso verified
‘with detilee eauulatioas deme fn [S| for a 37
coufigwaior wih all dala. Te ordor to coctkine
the secessing and utils chase. i is neaibie
tn computs te corbinsd avallebilily of kee
and also include the re-canantice advantage,
‘The vay tha Would be dave it lanza rhe
pratahifey of getting” service witkin a total
eyuire? Lie suck asthe outage Ceinition time
Tar That would iauluds ths chancs of yelling
arvioe within thal ee from the fits ry, plus
the chance inthe seen wy Cte Ast By Wat
locked) plus te Cin! ry Wye Cast tes
sve che) aul «0 on. AL some peitt, «will
fice te possible tm uy esis due wp che

retchisg tz waximen allowed Ty, Lenco i
fico ire the peubabiity oF petiag. servis
‘wovld be equal che provucl of the probably
fof iting urcess tp che 3A chaauel (Figure 3
‘wil the puhabiiy thatthe series ene wil he

Tees Jhan Tr (from Figue secur any ie
seeded aid ponible thon © secon ecto i
fdded correspiling wa the probably that
envice would to srovided within T, minus the
Hig i tok until de second Uy ack place,
rkigtod ly tae yall ef geking caus om
tee secone iy. The probaly of aettng aevest
OF the Seoul uy Hef omD equal 19 the
probability of gorcig aves par #3 ir the fest
lry and atl afer ties if we asiume a Bie
populatioe. af atraritisi, matdplied by he
lity of ying fir a escoad time which i
qual tothe otobabity of being bicksd che ret
line. Ta-a si-wilar vay, the teal sequence of
ties aie canputed wha ato untia diefereuce
being the probably oF Lying
ddecrenes arnsicerably since fr sxaople UF che
Blocking on ths Hest ty 8 O1, Maes probrblily
oF trying te several ims is G1, while far the
thied te 36 0-199. 1640 ane. Route 1s 0.0
and f0 on. As the musnbse of wries iereazes
fie we allow fer a larger Ty or se vole Ue
Tine batnvca setees ie sould Be porsiole tn
reduce che access chanel aloxkage peabaiily
ceumserahy and Aanee invsase ie uuinser el
suppocled airralls. However, as sae aus of
alloyatle sires increas” that ill eso
ingens the zoquest data traffic loud (je. wale
Toul in Table 3), mud hieace will dew slat t9
Trove the upposte elect of cedveing the sumer
of possible ainmfis tn support. Hanes, the
ues Lave a siyuifiearl avant: inieally ¢
example allawing for 7 or 3 meri is aauch
Feller thon ons) bet aoush higher is uel
‘eepineecde al cam cauae Wor rerite
Finaly sen coing the combined snulvace, it
should bo nazd Bat the same avirber of
sinoralts for both the ML nd che Data elute

soul We aed ela gece umbers” Eom

Migure 2 and 3 30 65 to Se coushlenl, Fe
wample we may urs a LOE socnlimaest tat
data packels save 0 be recived within 1 seecnd
tis mame, ane fgue al the wicher tt
Svorafis at will prevtuce a coral peobatlity a
is exalt 6.95 given al cies powsible using
ignics 2 and 3 data a6 sell the probit ity a
lrsing. ‘This corabined probably wis studied
and tie fests show better nimha a" anal
fan Weokicg at eke aecass channel aloe, but a
wore one besed ou the daly ehinael ap

cd. A future sly chow “oe mens
sors formally hut invested readers ean Wo the
‘ompututions simply by Tolling the pracedaie
are eed using dala glve: fie he plats of te
Fascewo fgurss. Wweas Zaual theta 1 seen Ty
Will up us aspires posse aud with Une uss of
3 da shansels and 8 aecess shane. wll eve
‘my opprositante nuucber of 25 tp 35 alcats hat
‘em bs supported usiag won cose seenetis With
serve nites helf of that in Table 1 t
‘ascammtlale the random wasted sot spaces 1
the seal systexa due ta shore packets occupying
Fall shts.” Speta th> secavs channels produced
the greatest “iitarion a6 i companed 29 te 3
ata cheanels which sauld have sevovaresleted
omy mere sient if it wae not tor
accessing limation. This ie evident fom
resell satel eurice en che 149 icmlt capaci
in Doe terminal aoa using only sale data
fhanncl but witht locking ist Ce a
channel Initafion. Taciasiug une accessing
tages is the sities Way’ ¢@-accom=wd:
fonre tefl on che 1 chunrsts, Again this #36
compared to an actual simwation aa’ in the
sadly wo Falla this i€ wil 32 slahorted 0 i
such tne cats

Conclusion

‘his study involved che computation oF
swailablfbleckoge of ve'zo and dala over
VIM, Moe 3 data Hak. The Hrlang H a3 used
lor a voisg ane thea

the Erkng Cas uve k
CPDLC Cate} to carpats the milility of
euch. Several pararmaier that offset the
availailicy rests were studied inelacing the
sate sail time, range of service data, amor
of availabe TDMA logieel chamneds, ard packet
size. ‘insrotns shee wey good avail of
the ity porion of the TOMA slot wFick
secvive the dati CPDLC riffs. ‘This
availbilly) wee thorgh led lea to he

‘Mazagamen! channels avalability where request
{er TDMA slots ars ten. Thue avalabitry we
omidernaly less haces Timing the overall
syseam dais wapabilty, ‘TW's » wus eyeu
te teary chavovs ax die M channels. Veicr ot
Ue cher aa pruvided te least sapacity end as
sel Je vone siguticant l-tog faater Him

Be access chantls if a wence env eve to be
fecconpovied hy a data shanael such ae fn the
212d ewafiguretion ‘ualraters ane

ranging die sane ita va Voie aed
dau, the lower coymity of fe 89 Is the
Alee'micing Factor a8 suc a sbaring 0” 2 single
lata chanel betwesr. mse tist oie conte
ach hsicg a sing'e wales shanral iy incre
spt. Ar pr2cent ray up lo 3 cations ave
alloyed oo snere a single data ale. with

sing a siygle vole chaste: eae. a the Jed
conligeratice. Ree su. fram the’ mtimbers

shown it appears Gal were can be done sc #
Single dacs. channel than 4 voice enue,
oui ad Hence a wen in eyes capacity

iv eminem. This wll be auch rere propaunc:
if in be fee voice tatfic wal be met
reducee even more reliance ow data and
CULLE specifiy. Finely, tke eestoler

ago linited
BP arcrafs in te sect (a mumbo? at
1S sizerafs ix corral is probab'y the swat
reiing fac compared 9 the Sonuneacations
Uinks capabiities. This ix also the case hance
Df tke requiem’ uf Baving one voles chanel
per conta

Presivus sluliss [4 on availble (requeny

chane's given Co-chamel — intesrence

requrreroms ean be Ticked with sfig study to

show ie oral syste

svailabilig. “Lean bp cauedet fren, the 20
thse the wie a” mulripls tsenenay

TDMA lege
combination of tie sealable froquaiey ehawels
ard she capably < 4 single ebuzrel (dene in
Ibis study} can provide sufficient support fer
tere taffic Iouds. Nor ths Wes, dis stay
ate ke pull Wuc where the Eniting Zar
are and where impuoverrenis con ponsihly be
apalied if ere cxpacity nasde in

Finally as wort going chat zany moet
results cat be oblsired sed on he
Fecracarions of ths study in a simple vay eh
‘ean zor the purpose, Per example aay fulure
‘arhaions ie afc lows, requremenss, cu be
szccuunted for by sitely varsing the apnecpuist
pwamcters of cis waffle dat rites wie using
ths som avalahiligy anrves and anroning fora
<Seleveat number ef vets, Simlany x change
in ar availability waiting Aime requizomest, oF
voles grace of serviea san te accounted for by
simply obsorving the same curves sh bate
be exiciing dua ardliferest port

Ter tule reeazatuendation or enhensement,
a few items can 32 thotght of which include
tsing qWiority qeouingaysiome ordre
rioily Ieeels acooaling fer nope
fev mote tonal vay: ‘leling oiber day
factors auch az pragagatie althongh those we
rwinimal: fnveedgeticg the otal avaiabiity in 5
bptiualy eae dhe eves deel (us apps lu
he random “voehosl se that te come closer 10
Mints Toes i372 meds rather chan MMC in
parle, arvesligatng ioprosemert 9 waratons
in he transport Leyes that can eedawe data fade
i geroval, Invowigace the difeceuce in
effciensy loses cases! hy te astee. sot
tal are due Io sol using portions 6 tar de
slots (lea a CPDLC wessige accuniec. 4
peition of dee Ste, Leesligaing
cnccmal idens such at the ariancages
fee tlie. and also the posits
‘uf data und voioe with a voice
prebmysion eapol icy st dh a ao: allocate
Yeleo channels wher. not wid Gotu ape gple
Lines fr gta nines)

References

1! Nations! Ainsyecy Systm Acchitecuce
TAA sive tangent cle ne,

fv ASC Progam, NASA, 200
bbupavwwrasesuasa guy, Mota Fld, CA

[3 GAD-G2-710, "Nasional Ais Space System"
Reput te Con Usted

Li M4. Shame, To Sgaen,
*Hroqueney Reuse, Call” Sopoctivs, and
Capacity Analyss of VL! Digital Link Mode
TDMA", Procslngs of die 3 dategsted
Cormenicacon and Tavigarions Confsicre,
Autpes, Maryland, 2003

[3 RTCA docraeal 2248, “Sigealin-spuce
sinimant aviation aysier;_pexlonusce
standards (MASPS) Zo" slvanoed VH™ digit
ela vemminiowsone ineleding compe siiny
‘wih digit ine tetanus, 2000

10 24, Comunuuicatians Syste
re Developumcar for alr Teathie
Menageont ard Aviation Weather Intnerttin
Dissesniaion, SAIC Toum May 2020,

OLR Kesaowski, M. Skaniza, R. Spence, B.
Apia, “hanasging Aeronautical
Cusmmenisasons Areicotare Canespts
Fhuure Ais Trullie Management Reqsiromcnts,”
S' Ka Band Uilizstion Conference. lay
Septeraer, 2002

[8 AD.Allen, Probability, Staistes and
Queueing “Theory wih Computer Stisnee

Applicstions. Boston: Acalem. Press, 950,

etree. Logiszaring
Top, Cleestand Ste Whisustin, yes Wo 3°
plished, 2:9,