Duc Ngoc Minh DANG e al. VOLUME: 23 |NUMBER: 2 |2025 |JUNE
Resea ch A icle
Enhancing IEEE 802.11ah Ne wo ks:
A Spa ial Mul i-Channel MAC P o ocol
Duc Ngoc Minh DANG1,∗
1AiTA Lab, Compu ing Fundamen al Depa men , FPT Uni e si y,
D1 S ee , Saigon Hi- ech Pa k, Long Thanh My Wa d, Thu Duc Ci y, Ho Chi Minh Ci y, Vie nam
[email p o ec ed]
∗Co esponding au ho : Duc Ngoc Minh Dang; [email p o ec ed]
DOI: 10.15598/aeee. 23i2.240513
A icle his o y: Recei ed May 23, 2024; Re ised Jul 02, 2024; Accep ed Sep 22, 2024; Published Jun 30, 2025.
This is an open access a icle unde he BY-CC license.
Abs ac . IEEE 802.11ah is designed o enhance
IoT ne wo ks by suppo ing nume ous s a ions, ex-
ending co e age ange, educing powe consump ion,
and ope a ing wi hin he sub-1 GHz band. The Re-
s ic ed Access Window is in oduced o mi iga e col-
lisions and imp o e ne wo k h oughpu when mul i-
ple s a ions con end o he channel simul aneously.
While he PHY laye in IEEE 802.11ah suppo s mul i-
ple channels wi h di e en bandwid hs, he MAC laye
only suppo s a single channel o communica ion be-
ween he Access Poin (AP) and s a ions. Howe e ,
ne wo k pe o mance can be imp o ed by enabling s a-
ions a di e en loca ions o exchange da a packe s on
di e en channels concu en ly. This pape p oposes
a Spa ial Mul i-channel MAC (SM-MAC) p o ocol o
IEEE 802.11ah, which di ides he AP’s co e age a ea
in o sec o s, each assigned a dedica ed channel. Each
sec o is se ed by wo Fo wa de s esponsible o elay-
ing da a packe s be ween s a ions and he AP. The pe -
o mance o he SM-MAC p o ocol is e alua ed agains
he IEEE 802.11ah MAC p o ocol in e ms o packe
deli e y a io, h oughpu , and ene gy e iciency.
Keywo ds
IoT ne wo ks, IEEE 802.11ah, Mul i-channel
MAC p o ocol, Res ic ed Access Window,
WiFi Halow.
1. In oduc ion
The In e ne o Things (IoT) is a as ne wo k o e -
e yday objec s, including de ices, ehicles, and ap-
pliances, ha can communica e and sha e in o ma-
ion wi h each o he . These de ices ange om sim-
ple home de ices o complex indus ial machine y, en-
abling communica ion wi h o he in e ne -connec ed
de ices o c ea e an in e connec ed ne wo k capa-
ble o au onomous da a exchange and ask execu ion.
IoT applica ions a e di e se and include sma homes,
sma ci ies, indus ial IoT, en i onmen al moni o ing,
ag icul u e, and heal hca e. IoT b ings a whole new
le el o connec i i y o he in o ma ion and communi-
ca ion echnology wo ld, o e ing ubiqui ous connec i -
i y any ime, anywhe e, o any hing. The de elopmen
o wi eless communica ion echnology ha sa is ies he
needs o di e se In e ne o Things applica ions, in-
cluding long- ange ansmission, la ge-scale connec i -
i y, low powe consump ion, bounded delay, and s able
h oughpu , is essen ial. Wi eless Pe sonal A ea Ne -
wo ks, such as ZigBee and Blue oo h Low Ene gy, o e
medium da a a es a a sho ange. Low-Powe Wide
A ea Ne wo k echnologies, such as LoRa, SigFox, NB-
IoT, eMTC, Wi-SUN, and IEEE 802.11ah, suppo low
o medium da a a es and a e ocused on long- ange
communica ions. IEEE 802.11ah, also called Wi-Fi
HaLow, is a ecen ly in oduced Wi-Fi s anda d ha
p o ides he highes da a a e and a medium ans-
mission ange be ween WPAN and mos LPWAN ech-
nologies (Fig. 1).
IEEE 802.11ah [2] o e s ne wo k connec i i y o
up o 8,192 s a ions wi h da a a es anging om 150
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Fig. 1: WPAN and LPWAN echnologies [1].
kbps o 78 Mbps wi hin a 1 km ansmission ange. I
suppo s di e en channel bandwid hs on unlicensed
sub-GHz equency bands, including 863–868 MHz,
755–787 MHz, and 902–928 MHz in Eu ope, China,
and No h Ame ica, espec i ely (Fig. 2). In o de
o imp o e high scalabili y and ene gy e iciency, IEEE
802.11ah inco po a es no el ea u es, such as a sho
MAC heade , as associa ion and au hen ica ion, a
Res ic ed Access Window (RAW), a T a ic Indica-
ion Map (TIM), a Ta ge Wakeup Time (TWT), and
Hie a chical O ganiza ion.
902
MHz
1 MHz
2 MHz
4 MHz
16 MHz
8 MHz
928
MHz
Fig. 1: US channeliza ion.
Fig. 2: US channeliza ion.
To accommoda e a la ge numbe o s a ions, IEEE
802.11ah u ilizes a hie a chical Associa ion Iden i ica-
ion (AID) s uc u e o ganized in o pages, blocks, sub-
blocks, and de ice posi ion indexes. S a ions wi hin
a page a e alloca ed o di e en Deli e y T a ic Indi-
ca ion Map (DTIM) pe iods, DTIM pe iods o TIM
pe iods, and TIM pe iods o RAW slo s in a hie a chi-
cal manne . Wi hin a TIM pe iod, he e may be one
o mo e RAWs, and he RAW mechanism is in oduced
o educe collisions and in e e ence among s a ions.
The use o scalable communica ion echnologies o
connec a la ge numbe o de ices o IoT applica ions
is essen ial. Howe e , cu en implemen a ions equi e
he use o a combina ion o di e en echniques, lead-
ing o inc eased ne wo k complexi y. In addi ion o en-
hancing scalabili y, u ilizing equencies below 1 GHz
and suppo ing a ious modula ion and coding schemes
(MCS) allows o easy con igu a ion o IoT applica-
ions. Da a a es anging om 150 Kbps o 78 Mbps
a e sui able o low-powe IoT de ices. Fu he mo e,
IoT de ices only need o wake up o sho pe iods o
ansmi da a and en e sleep mode o he emaining
ime o conse e ene gy.
The emainde o his pape is o ganized as ollows.
Sec ion 2 desc ibes he li e a u e e iew on MAC p o-
ocols in IEEE 802.11ah ne wo ks. Sec ion 3 p esen s
he key ea u es o he IEEE 802.11ah MAC p o o-
col. The de ails o he p oposed SM-MAC p o ocol a e
p esen ed in Sec ion 4. The pe o mance analysis and
e alua ion a e p esen ed in Sec ions 5 and 6, espec-
i ely. Finally, Sec ion 7 concludes ou wo k.
2. Rela ed wo ks
RAW is designed o mi iga e he collisions among s a-
ions in IEEE 802.11ah by using a s a ion g ouping
mechanism. Raeesi e al. [3] p oposed a model o an-
alyze sa u a ion h oughpu , packe delay, and ene gy
e iciency o known collision p obabili y and packe
e o a e. Tian e al. [4] e alua ed he impac o
he numbe o s a ions and a ic condi ions on he
op imal alues o he numbe o RAW g oups. An
adap i e RAW g oup is necessa y o maximize pe -
o mance unde dynamic condi ions. By aking in o
accoun he ese o backo s a e a he beginning o
he RAW slo , Kho o e al. [5] de eloped a ma h-
ema ical model o sa u a ed s a e based on Bianchi’s
model [6], a disc e e- ime Ma ko chain model, o es i-
ma e h oughpu and ene gy consump ion o he RAW
wi h he c oss-slo bounda y. Chang e al. [7] p oposed
a a ic-awa e g ouping algo i hm o imp o e channel
u iliza ion.
Šlji o e al. [8] in es iga ed how RAW and TIM seg-
men a ion in luence scalabili y, h oughpu , la ency,
and ene gy e iciency in he p esence o bidi ec ional
TCP/IP a ic. Kai e al. [9] designed he a ic
dis ibu ion-based senso g ouping scheme o balance
he ene gy e iciency o di e en g oups in la ge-scale
access ne wo ks. Nawaz e al. [10] p oposed a me hod
in which he RAW ame is di ided in o wo sub-
ames, and he iming o RAW slo s o each sub- ame
is selec ed based on g oup size, esul ing in imp o ed
h oughpu o RAW in clus e ing scena ios. Ahmed
and Hussain [11] in oduced a me hod o he AP o
p edic ansmission imes by di iding RAW in o wo
phases: a compe ing phase and a ese a ion phase,
enabling he scheduling o da a packe s be o e hei a -
i al. This ad anced scheduling educes channel com-
pe i ion and unnecessa y wake-ups, making i sui able
o la ge ne wo ks wi h a ocus on low la ency and en-
e gy e iciency. Sangee ha e al. [12] p esen ed an ana-
ly ical model o e alua e he sa u a ion h oughpu o
IEEE 802.11ah wi h di e en da a a es and p oposed
a clus e ing algo i hm based on da a a es o imp o e
ai ness and o e all sys em h oughpu .
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Model-Based RAW Op imiza ion Algo i hm (Mo-
ROA) [13] used he ained su oga e RAW model o
de e mine he op imal RAW con igu a ion in di e en
ne wo k and a ic condi ions. Mondal e al. [14] e al-
ua ed ne wo k pe o mance, pa icula ly h oughpu ,
by a ying he numbe o s a ions and RAW g oups.
Thei indings indica ed ha he op imal numbe o
RAW g oups depends on he o al numbe o s a ions
wi hin he ne wo k. Unlike he ixed RAW size in
IEEE 802.11ah, Fahad e al. [15] p oposed a me hod
enabling he AP o dynamically adjus he RAW size
based on ne wo k packe ansmission and he num-
be o ansmi ing s a ions. Ta ami e al. [16] p o-
posed an analy ical model based on a wo-le el e-
newal p ocess o assess channel access con en ion in
IEEE 802.11ah ne wo ks ope a ing unde Rayleigh ad-
ing condi ions wi h cap u e e ec s. The pape also
in oduced a Load-Awa e Channel Alloca ion (LACA)
algo i hm designed o op imize RAW slo du a ions o
comple e packe deli e y while maximizing channel u i-
liza ion. Mondal e al. [17] p oposed a Machine Lea n-
ing (ML)-based s a ion g ouping model ha accu a ely
p edic s RAW con igu a ion pa ame e s, aiming o en-
hance RAW pe o mance in a eal-wo ld IoT ne wo k.
Addi ionally, i in oduces a channel access echnique
ha employs an ML model o assign nodes o ese e
slo s and adjus hei slo du a ions when nodes canno
access he channel due o collision de ec ion. Nabuuma
e al. [18] elimina ed collisions in he zoned ne wo k by
se ing s a ion back-o alues acco ding o hei AID
posi ion wi hin he g oup.
Jamali e al. [19] in oduced an associa ion con-
ol me hod aimed a educing blocking p obabili y in
IEEE 802.11ah mIoT ne wo ks h ough wo schemes:
limi ing he numbe o de ices associa ed wi h an AP
wi hou u ilizing in o ma ion abou IoT de ice a ic,
and de e mining he numbe o de ices an AP can ad-
mi based on he maximum a ic gene a ed by hose
de ices. Mahesh and Ha igo indan [20] p oposed a
se ice di e en ia ion model o G oup-Synch onized
Dis ibu ed Coo dina ion Func ion (GS-DCF), g oup-
ing s a ions and assigning p io i ies based on hei da a
ansmission needs. In he Regis a ion-Based Colli-
sion A oidance Mechanism [21], he AP schedules s a-
ion da a ansmission based on p e- egis e ed back-o
alues o p e en collisions.
Exis ing wo ks [22–24] ha e p oposed sec o ized
g ouping. In [22], s a ions a e di ided in o sec o s,
hen u he g ouped acco ding o he numbe o s a-
ions and hei loca ion. By u ilizing a spa ially o hog-
onal access me hod, he s a ions in di e en g oups
wi hin di e en sec o s can access he channel du -
ing hei assigned RAW slo s. This app oach educes
he packe collision p obabili y, leading o a signi i-
can imp o emen in he ne wo k h oughpu and a
dec ease in sys em delay. In he di ec ional ah MAC
p o ocol (Dah) [23,24], he AP pa i ions i s co e -
age in o di e en sec o s, employing an ennas capable
o ope a ing in bo h omnidi ec ional and di ec ional
modes. A RAW is di ided in o ou SubRAWs, wi h
each SubRAW aligned o a speci ic dual sec o . Du -
ing a gi en RAW slo , s a ions wi hin a pa icula dual
sec o con end o channel access o communica e wi h
he AP wi hou collisions. Bo h p oposals also educe
he numbe o s a ions con ending o he channel com-
pa ed o he IEEE 802.11ah p o ocol, esul ing in a sig-
ni ican imp o emen in packe deli e y a io and sys-
em h oughpu . Addi ionally, he Dah p o ocol also
implemen s an adap i e ansmission powe scheme o
uplink ansmission o imp o e he ne wo k ene gy e -
iciency in [24]. Howe e , hese p oposals a e imple-
men ed wi h a single channel a he MAC laye , and
hey canno ully u ilize he mul iple-channel esou ces.
The SF-MAC p o ocol [25] enables s a ions o commu-
nica e wi h he AP h ough Fo wa de s ope a ing on
di e en channels. By o ganizing s a ions in o sec o s
and u ilizing mul iple channels o da a ansmissions,
he SF-MAC imp o es packe deli e y a io and o e all
ne wo k h oughpu .
This pape in oduces a Spa ial Mul i-channel
Medium Access Con ol (SM-MAC) p o ocol designed
o IEEE 802.11ah ne wo ks. The p o ocol employs a
spa ial o ganiza ion s a egy, clus e ing s a ions in o
dis inc sec o s based on hei geog aphical loca ions.
In e media e s a ions, known as Fo wa de s, elay com-
munica ion be ween he AP and s a ions wi hin each
sec o . Du ing each RAW, Fo wa de s and s a ions in
a gi en sec o ope a e on sepa a e channels, while he
AP al e na es be ween he channels o each sec o o
ecei e and ansmi da a packe s. Compa ed o IEEE
802.11ah, he SM-MAC p o ocol signi ican ly imp o es
ne wo k pe o mance by aking ad an age o mul iple
channel esou ces.
3. IEEE 802.11ah MAC
p o ocol
3.1. Associa ion and Au hen ica ion
IEEE 802.11ah suppo s wo app oaches o Associa-
ion and Au hen ica ion: he Cen alized Au hen ica-
ion Con ol (CAC) and he Dis ibu ed Au hen ica-
ion Con ol (DAC) app oaches. In he CAC app oach,
he s a ions choose a andom numbe in he ange [0,
1023]. The AP se s an Au hen ica ion Con ol Th esh-
old (ACT) and b oadcas s i in e e y beacon in e al.
Each s a ion wi h a andom numbe less han o equal
o he h eshold ACT is allowed o send an Au hen-
ica ion Reques o he AP wi hin he same beacon
in e al. O he wise, i is no allowed o access he
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channel un il he nex beacon in e al. In he DAC
app oach, each beacon in e al is di ided in o Au hen-
ica ion Con ol Slo s (ACSs) o equal du a ion Tac.
S a ions andomly selec a beacon in e al mand an
ACS l o send hei Au hen ica ion Reques . I he
Au hen ica ion Reques a emp ails, he s a ion in-
c eases he numbe o au hen ica ion e ies and e-
selec s mand l. Wi hin he ACS, he s a ion a emp s
o access he channel using he Enhanced Dis ibu ed
Channel Access (EDCA) mechanism.
3.2. Res ic ed Access Window
IEEE 802.11ah in oduces he Res ic ed Access Win-
dow mechanism o mi iga e collisions and imp o e
h oughpu in high-densi y IoT ne wo ks, whe e a la ge
numbe o s a ions equi e access o he channel simul-
aneously. I combines TDMA and CSMA/CA, di id-
ing he s a ions in o g oups, and allowing only hose
s a ions belonging o speci ic g oups o access he chan-
nel using Dis ibu ed Coo dina ion Func ion (DCF)
and Enhanced Dis ibu ed Channel Access (EDCA) a
ce ain imes. Fig. 3 illus a es he RAW g ouping
mechanism. The channel access ime is di ided in o
se e al small in e als, some o which a e assigned o
RAWs, while o he s a e conside ed sha ed channel ai -
ime and can be accessed by all s a ions. Each beacon
in e al can include mul iple RAWs, and each RAW is
u he di ided in o RAW slo s. S a ions assigned o
a RAW a e e enly spli ac oss he RAW slo s using a
ound- obin app oach. I a s a ion belongs o a RAW
g oup, i is allowed o con end o medium access only
a he beginning o i s assigned RAW slo and will no
a emp o access he channel du ing any o he RAW
slo wi hin ha RAW. The numbe o slo s NRAW , Slo
Fo ma , and he Slo Du a ion Coun Ca e also spec-
i ied in he RPS elemen . A he beginning o he bea-
con in e al, he AP b oadcas s a beacon ame wi h
a RAW Pa ame e Se (RPS) ha speci ies he RAW-
ela ed in o ma ion, such as g oup s a ime, du a ion,
and he s a ions assigned o RAW(s).
Fig. 3: RAW mechanism [1].
A s a ion de e mines he index o i s assigned RAW
slo , islo as ollows [8]
islo = (x+No se ) mod NRAW (1)
whe e No se is he o se alue used o imp o e he
ai ness among he s a ions, and xis he posi ion index
o he s a ion’s AID in he TIM bi map; o he wise,
xis he s a ion’s AID. Fig. 4 shows he RAW slo
assignmen o paged and non-paged s a ions.
Fig. 4: RAW slo assignmen [8].
4. The p oposed SM-MAC
p o ocol
Fig. 5 shows an IEEE 802.11ah ne wo k wi h Ns a-
ions and a single AP o he SM-MAC p o ocol. The
AP is equipped wi h wo anscei e s, each suppo ing
omnidi ec ional and di ec ional modes. Addi ionally,
he AP suppo s a highe da a a e on he channel a,
while s a ions ope a e a a educed da a a e on di -
e en channels depending on hei loca ion. The AP
di ides i s co e age in o S= 8 sec o s, and s a ions
in sec o s, (s= 0, ..., 7) ope a e on he co esponding
channel s. A dual sec o is de ined as wo opposi e sec-
o s; e.g., sec o s 0 and 4 a e conside ed o be a dual
sec o (0, 4). Since s a ions in each sec o a e wi hin
ansmission ange o each o he , he hidden e minal
p oblem is elimina ed. Fo e e y sec o s, he AP as-
signs a Uplink Fo wa de (FWDu
s) and a Downlink
Fo wa de (FWDd
s). A Fo wa de ei he ecei es he
downlink da a packe s om he AP and passes hem o
s a ions on he co esponding channel so collec s he
uplink da a packe s om hei s a ions and ansmi s
hem o he AP on channel s.
Du ing he Au hen ica ion/Associa ion p ocess, a
new s a ion a emp s o connec wi h he AP on chan-
nel a. Based on he signal ecei ed om he s a ion,
he AP de e mines he s a ion’s loca ion. The AP as-
signs a 16-bi Associa ion ID (AID) o he s a ion,
whe e he sec o index is ep esen ed by he h ee mos
signi ican bi s (bi s 0-2). Since he AID is 16 bi s long,
he SM-MAC suppo s up o 65,528 s a ions, wi h each
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a
DL SubRAW
0
7
0 7
0NR-1
UL SubRAW
AP
FWDd
0
AP
FWDd
70 7
AP
FWDu
0
AP
FWDu
7
STA{0} FWDu
0FWDd STA{0}
0
STA{7} FWDu
7FWDd STA{7}
7
0NR-1
RAW slo FD slo
ud
RAW
10
7
65
4
2
3
*
**
*
*
*
*
*
7
0
1
2
3
4
5 6
Sec o Page Block Sub-block S a ion
Bi h 0 3 5 10 13 15
001 00 00001 001 101
S a ion
+
+
+
+
+
++
a
+
Access Poin
Sec o
*UL Fo wa de
S a ion
+DL Fo wa de
Fig. 5: Topology o he SM-MAC p o ocol.
sec o ha ing a maximum numbe o s a ions. Simila
o [23, 24], he AID hie a chy includes sec o , page,
block, subblock, and s a ion, as shown in Fig. 6. The
i s h ee bi s o he AID indica e he s a ion’s sec o ,
enabling i o communica e wi h o wa de s FWDu
s
and FWDd
son he channel s.
a
DL SubRAW
0
7
0 7
0NR-1
UL SubRAW
AP
FWDd
0
AP
FWDd
70 7
AP
FWDu
0
AP
FWDu
7
STA{0} FWDu
0FWDd STA{0}
0
STA{7} FWDu
7FWDd STA{7}
7
0NR-1
RAW slo FD slo
ud
RAW
10
7
65
4
2
3
*
**
*
*
*
*
*
7
0
1
2
3
4
5 6
Sec o Page Block Sub-block S a ion
Bi h 0 3 5 10 13 15
001 00 00001 001 101
S a ion
+
+
+
+
+
++
a
+
Access Poin
Sec o
*UL Fo wa de
S a ion
+DL Fo wa de
Fig. 6: AID s uc u e in he SM-MAC p o ocol.
In he SM-MAC p o ocol, a RAW is di ided in o 2
SubRAWs: DL SubRAW and UL Sub RAW, as shown
in Fig. 7. On he channel a, each SubRAW is u he
di ided in o 8 FD slo s o he collision- ee ansmis-
sions be ween AP and o wa de s. On each channel
s, SubRAW is di ided in o NRRAW slo s o he
con en ion-based ansmissions be ween he o wa de
and i s s a ions. Each RAW slo has a du a ion o
DSlo .
In DL SubRAW, DL Fo wa de s FWDd
s ecei e
downlink packe s om he AP on he channel aon be-
hal o hei s a ions, while he s a ions ansmi hei
uplink packe s o he co esponding UL Fo wa de s
FWDu
son he di e en channel s. In UL SubRAW,
UL Fo wa de s FWDu
s ansmi he ecei ed uplink
packe s o he AP on he channel a, while he s a ions
ecei e hei downlink packe s om he co esponding
DL Fo wa de FWDd
son he di e en channel s.
Fig. 8 illus a es he uplink (UL) communica ion
p ocess o s a ions in sec o s. Du ing he DL Sub-
RAW, s a ions in sec o s, deno ed STA{s}, con end
o channel access o ansmi he uplink packe s o
hei UL Fo wa de FWDu
swi hin he assigned RAW
slo s on he channel s. Subsequen ly, in he UL Sub-
RAW, he UL Fo wa de FWDu
s o wa ds he ecei ed
uplink packe s o he AP in he co esponding FD slo
on he channel aa a high da a a e in a collision- ee
manne .
Fig. 9 illus a es he downlink (DL) communica ions
om he AP o he s a ions in sec o s. In he FD slo
o he DL SubRAW, he DL Fo wa de FWDd
s ecei es
he downlink packe s o i s s a ions on he channel a.
In he UL SubRAW, he s a ions con end o ecei e
downlink packe s om he DL Fo wa de FWDd
son
he channel sin he co esponding RAW slo s.
5. Analy ical Model
Conside an IEEE 802.11ah ne wo k comp ising a sin-
gle AP and Ns a ions andomly dis ibu ed wi hin he
AP’s one-hop co e age a ea. The s a ions always ha e
uplink da a o ansmi o he AP, while he AP also
always has downlink da a o he s a ions. The down-
link and uplink SubRAWs con ain Nd
Rand Nu
RRAW
slo s, espec i ely.
Ou analy ical model assumes ha ns a ions simul-
aneously con end o channel access o communica e
wi h hei o wa de s in a RAW slo . Following he
app oach in [7,9,11], we employ a Ma ko chain model
unde sa u a ed condi ions as desc ibed in [6]. Le b( )
and s( )deno e he s ochas ic p ocesses ep esen ing
he back-o coun e and back-o s age, espec i ely,
a slo ime . The disc e e- ime Ma ko chain models
he wo-dimensional p ocess {s( ), b( )}, as shown in
Fig. 10. The maximum back-o s age is deno ed by
m, and he con en ion window (CW) o he i h back-
o s age is calcula ed as Wi= 2i·W0, whe e i anges
om 0 o m.
The s a ion a emp s o ansmi a packe when he
back-o coun e eaches ze o. The p obabili y, τ, ha
a s a ion ansmi s a packe in a ime slo is [6]
τ=2(1 −2p)
(1 −2p)(1 + W0) + pW0(1 −(2p)m)(2)
The collision occu s when mo e han one s a ion
ansmi s in a ime slo . The condi ional collision p ob-
abili y pis assumed cons an and independen [6]
p= 1 −(1 −τ)n−1(3)
The channel can be in one o h ee s a es: idle, suc-
cess ul, o collision. Le pilde,psuc and pcol deno e he
p obabili y ha he channel is idle, he channel has a
success ul ansmission, and he channel has collisions,
espec i ely
©2025 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 109
Duc Ngoc Minh DANG e al. VOLUME: 23 |NUMBER: 2 |2025 |JUNE
a
DL SubRAW
0
7
0 7
0NR-1
UL SubRAW
AP
FWDd
0
AP
FWDd
70 7
AP
FWDu
0
AP
FWDu
7
STA{0} FWDu
0FWDd STA{0}
0
STA{7} FWDu
7FWDd STA{7}
7
0NR-1
RAW slo FD slo
ud
RAW
10
7
65
4
2
3
*
**
*
*
*
*
*
7
0
1
2
3
4
5 6
Sec o Page Block Sub-block S a ion
Bi h 0 3 5 10 13 15
001 00 00001 001 101
S a ion
+
+
+
+
+
++
a
+
Access Poin
Sec o
*UL Fo wa de
S a ion
+DL Fo wa de
Fig. 7: The ope a ion in he Res ic ed Access Window o he SM-MAC p o ocol .
a
DL SubRAW
0
7
0 7
0NR-1
UL SubRAW
AP
FWDd
0
AP
FWDd
70 7
AP
FWDu
0
AP
FWDu
7
STA{0} FWDu
0FWDd STA{0}
0
STA{7} FWDu
7FWDd STA{7}
7
0NR-1
RAW slo FD slo
ud
RAW
10
7
65
4
2
3
*
**
*
*
*
*
*
7
0
1
2
3
4
5 6
+
+
+
+
+
++
a
+
Access Poin
Sec o
*UL Fo wa de
S a ion
+DL Fo wa de
SIFS
SIFS
FDs
STA{s}
SIFS
SIFS
AP
FWDds
Sec o Page Block Sub-block S a ion
Bi h 0 3 5 10 13 15
001 00 00001 001 101
S a ion
FD slo
a
s
RAW slo
STA{s}
AP
FWDus
FD slo
a
s
RAW slo
Fig. 8: Uplink communica ion in he SM-MAC p o ocol.
a
DL SubRAW
0
7
0 7
0NR-1
UL SubRAW
AP
FWDd
0
AP
FWDd
70 7
AP
FWDu
0
AP
FWDu
7
STA{0} FWDu
0FWDd STA{0}
0
STA{7} FWDu
7FWDd STA{7}
7
0NR-1
RAW slo FD slo
ud
RAW
10
7
65
4
2
3
*
**
*
*
*
*
*
7
0
1
2
3
4
5 6
+
+
+
+
+
++
a
+
Access Poin
Sec o
*UL Fo wa de
S a ion
+DL Fo wa de
SIFS
SIFS
FDs
STA{s}
SIFS
SIFS
AP
FWDds
Sec o Page Block Sub-block S a ion
Bi h 0 3 5 10 13 15
001 00 00001 001 101
S a ion
FD slo
a
s
RAW slo
STA{s}
AP
FWDus
FD slo
a
s
RAW slo
Fig. 9: Downlink communica ion in he SM-MAC p o ocol.
WSA(E-F)
WSA(A-B)
WSA(C-D)
a
DATA
(b-R2)
DL SubRAW
Emg(A)
DATA
(E-F)
Time
Emg(c)
DATA
(C-D)
DATA
(A-B)
pidle σ
#2 #3 #4
Emg: Sa e y message
WSA: WSA handshake
DATA: Da a ansmission
0
7
0 7
0NR-1
UL SubRAW
AP
FDd
0
AP
FDd
70 7
AP
FDu
0
AP
FDu
7
STA{0} FDu
0FDd STA{0}
0
STA{7} FDu
7FDd STA{7}
7
0NR-1
RAW slo FD slo
STA APAP STA
DL RAW UL RAW
0NR-1 0NR-1
u
u
d
d
b) RAW in Mah p o ocol
a) RAW in IEEE 802.11ah
RAW
Idle Success ul Collision
psucTsuc pcolTcol
RTS CTS DATA ACK
SIFS SIFS SIFS DIFS
RTS DIFS
Success ul ansmission
Collision ansmission
0,0 0,1 0,2
1 1 0,W0-2 0,W0-1
1
(1-p)/W0
(1-p)/W0
i,0 i,1 i,2
1 1 i,Wi-2 i,Wi-1
1
p/Wi
p/Wi
m,0 m,1 m,2
1 1 m,Wm-2 m,Wm-1
1
p/Wm
p/Wm
i-1,0
1-p
1-p
1-p
1-p
p/Wmp/Wm
Fig. 10: Ma ko chain o he sa u a ed ne wo k.
pidle = (1 −τ)n
psuc =nτ(1 −τ)n−1
pcol = 1 −(1 −τ)n−nτ(1 −τ)n−1
(4)
WSA(E-F)
WSA(A-B)
WSA(C-D)
a
DATA
(b-R2)
DL SubRAW
Emg(A)
DATA
(E-F)
Time
Emg(c)
DATA
(C-D)
DATA
(A-B)
pidle
#2 #3 #4
Emg: Sa e y message
WSA: WSA handshake
DATA: Da a ansmission
0
7
0 7
0NR-1
UL SubRAW
AP
FDd
0
AP
FDd
70 7
AP
FDu
0
AP
FDu
7
STA{0} FDu
0FDd STA{0}
0
STA{7} FDu
7FDd STA{7}
7
0NR-1
RAW slo FD slo
STA APAP STA
DL RAW UL RAW
0NR-1 0NR-1
u
u
d
d
b) RAW in Mah p o ocol
a) RAW in IEEE 802.11ah
RAW
Idle Success ul Collision
psuc pcol
RTS CTS DATA ACK
SIFS SIFS SIFS DIFS
RTS DIFS
Success ul ansmission
Collision ansmission
0,0 0,1 0,2
1 1 0,W0-2 0,W0-1
1
(1-p)/W0
(1-p)/W0
i,0 i,1 i,2
1 1 i,Wi-2 i,Wi-1
1
p/Wi
p/Wi
m,0 m,1 m,2
1 1 m,Wm-2 m,Wm-1
1
p/Wm
p/Wm
i-1,0
1-p
1-p
1-p
1-p
p/Wmp/Wm
σTsuc Tcol
Fig. 11: Vi ual ansmission cycle.
Le δand σ ep esen he p opaga ion delay and
an emp y slo ime du a ion, espec i ely. Fig. 11
illus a es a i ual ansmission cycle wi h h ee pos-
sible s a es: idle, success ul ansmission, and collision
ansmission. The a e age ime o a i ual ansmis-
sion cycle and each success ul packe ansmission a e
deno ed as E[TC]and E[TXsuc], espec i ely, and a e
gi en by
E[TC] = pidleσ+psucTsuc +pcolTcol
E[TXsuc] = pidle
psuc σ+pcol
psuc Tcol +Tsuc (5)
whe e Tsuc and Tcol a e he du a ions o a success ul
ansmission and a collision ansmission, espec i ely.
We use he supe sc ip d/u o DL and UL communi-
ca ions wi hou loss o gene ali y, espec i ely. Fo DL
and UL communica ions, Tsuc and Tcol a e de e mined
as ollows
Td
suc =Tps_pol +Td
da a +Tack + 2Tsi s + 3δ+Tdi s
Tu
suc =T s +Tc s +Tu
da a +Tack + 3Tsi s + 4δ+Tdi s
Td
col =Tps_pol +δ+Tdi s
Tu
col =T s +δ+Tdi s (6)
The numbe o da a packe s ansmi ed success ully
in a RAW slo is gi en by
Nsuc =DSlo
E[TXsuc](7)
©2025 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 110
Duc Ngoc Minh DANG e al. VOLUME: 23 |NUMBER: 2 |2025 |JUNE
The o al numbe o packe s ha a e ansmi ed in
a RAW slo is
N x =Nsuc
(1 −τ)n−1(8)
Le Pibe he powe consump ion o a s a ion in an
idle s a e. The a e age ene gy consump ion in each
ansmission cycle consis s o he ene gy consump ion
in an idle s a e, he ene gy consump ion o success ul
ansmission, and he ene gy consump ion when a col-
lision happens. In case o a success ul ansmission,
a ansmi e consumes ene gy o E x and a ecei e
consumes ene gy o E x while he o he s a ions con-
sume ene gy o PiTsuc. In case o a collision ansmis-
sion among is a ions, hese s a ions consume ene gy o
Ecol, while he o he s a ions consume ene gy o PiTcol.
The a e age ene gy consump ion in each ansmission
cycle is
E[ET C ] = pidlenPiσ+psuc (E x +E x + (n−2)PiTsuc)
+
n
P
i=2 n
iτi(1 −τ)n−i(iEcol + (n−i)PiTcol)
(9)
Nex , we compa e he pe o mance o he IEEE
802.11ah and he p oposed SM-MAC p o ocol in e ms
o packe deli e y a io and h oughpu . Conside -
ing a ne wo k wi h Ns a ions, he a e age numbe o
con ending s a ions in each RAW slo o he IEEE
802.11ah and he SM-MAC p o ocol is as gi en in
Tab. 1.
Tab. 1: Numbe o s a ions in each RAW slo
IEEE 802.11ah SM-MAC
DL RAW/SubRAW nd
ah =N
Nd
R
nd
sm =N/8
Nd
R
UL RAW/SubRAW nu
ah =N
Nu
Rnu
sm =N/8
Nu
R
The p obabili ies ha a s a ion in he IEEE
802.11ah p o ocol ansmi s a packe in a ime slo o
downlink o uplink a e deno ed by τd
ah and τu
ah, espec-
i ely. Simila ly, he p obabili ies o he SM-MAC
p o ocol a e ep esen ed by τd
sm and τu
sm, espec i ely.
5.1. Pe o mance Analysis o IEEE
802.11ah
The packe deli e y a io (PDR) o he downlink (DL)
and uplink (UL) RAW is
PDRd/u
ah = (1 −τd/u
ah )nd/u
ah −1(10)
Le DSlo deno e he du a ion o each RAW slo .
The o al numbe o success ully ansmi ed packe s
downlink and uplink communica ion
Nd/u
ah_suc =Nd/u
R
DSlo
E[TXd/u
ah_suc](11)
whe e E[TXd/u
ah_suc]is he a e age ime o each suc-
cess ul packe ansmission o DL/UL communica ion.
Le E[P] ep esen he a e age packe payload
leng h. Th oughpu is calcula ed as
Sd/u
ah =Nd/u
ah_sucE[P]
TRAW
(12)
Le Ehene gyd/u
ah ibe he o al ene gy consump ion
o downlink/uplink communica ions in a RAW. The
ene gy e iciency ηis de ined as he a io be ween suc-
cess ully ansmi ed da a and ene gy consump ion.
ηd/u
ah =Nd/u
ah_sucE[P]
Ehene gyd/u
ah i(13)
5.2. Pe o mance Analysis o he
SM-MAC p o ocol
The numbe o success ully ansmi ed packe s o
downlink/uplink communica ions
Nd/u
SubRAW _suc =Nd/u
R
DSlo
EhTXd/u
sm_suci(14)
The o al numbe o da a packe s ansmi ed in
downlink/uplink communica ions
Nd/u
SubRAW _ x =Nd/u
sm_suc
(1 −τd/u
sm )nd/u
sm −1(15)
Le TXsuc be he ansmission du a ion o each
da a packe in he FD slo on channel a, and i can
be calcula ed as
TXd/u
suc =Td/u
da a +Tack + 2Tsi s + 2δ(16)
The o al da a packe s ansmi ed in each FD slo
Md/u
F D_suc =FDslo
TXd/u
suc
(17)
The packe deli e y a io o downlink/uplink com-
munica ions
PDRd/u
sm =min(Nd/u
SubRAW _suc, Md/u
suc )
min(Nd/u
SubRAW , Md/u
F D_suc)(18)
©2025 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 111
Duc Ngoc Minh DANG e al. VOLUME: 23 |NUMBER: 2 |2025 |JUNE
The o al da a packe s ansmi ed success ully in
downlink/uplink communica ions
Nd/u
sm_suc = 8 ·min(Nd/u
SubRAW _suc, Md/u
F D_suc)(19)
The downlink/uplink h oughpu
Sd/u
sm =Nd/u
sm_sucE[P]
TRAW
(20)
Le Ehene gyd/u
sm ibe he o al ene gy consump ion
o DL/UL communica ion in each RAW. The ene gy
e iciency o he SM-MAC p o ocol is gi en by
ηd/u
sm =Nd/u
sm_sucE[P]
Ehene gyd/u
sm i(21)
6. Pe o mance E alua ion
An e en -d i en simula ion p og am implemen ed in
MATLAB is employed o alida e ou model. Based on
he pe o mance analysis in Sec ion 5, he pe o mance
o UL and DL communica ion is compa able. Conse-
quen ly, his sec ion p esen s he pe o mance e alua-
ion o UL communica ion in sa u a ed condi ions in
e ms o packe deli e y a io (PDR), h oughpu , and
ene gy e iciency. The simula ion pa ame e s used o
his e alua ion a e summa ized in Tab. 2.
6.1. Pe o mance compa ison e sus
he numbe o s a ions
This sec ion compa es he pe o mance o he SM-
MAC p o ocol o he IEEE 802.11ah p o ocol unde
a ying numbe s o s a ions. The numbe o RAW
slo s Nu
Ris se o 20 slo s. The numbe o s a ions
is changed om 20 s a ions o 8,000 s a ions. The
s a ions a e alloca ed o RAW slo s based on Eq. 1.
Analy ical esul s a e deno ed “-ana”, while simula ion
esul s a e deno ed “-sim” in he igu es. Wi h he sim-
pli ica ions and assump ions inhe en in ou Ma ko
chain model [6] p oposed by Bianchi, he e may be
some disc epancies be ween analy ical and simula ion
esul s.
Fig. 12 illus a es he p obabili y o success ul
packe ansmission o he SM-MAC p o ocol com-
pa ed o he IEEE 802.11ah MAC p o ocol unde a y-
ing numbe s o s a ions. As he numbe o s a ions in-
c eases, he numbe o s a ions in each RAW slo also
inc eases, leading o an inc eased p obabili y o colli-
sion when compe ing o channel access. F om he e,
Fig. 12: Packe deli e y a io e sus he numbe o s a ions.
he p obabili y o success ul packe ansmission de-
c eases wi h an inc easing numbe o s a ions. How-
e e , he numbe o s a ions in he SM-MAC p o ocol
con ending o he channel in a RAW slo is less han
he numbe o s a ions in he IEEE 802.11ah p o o-
col since he s a ions a e di ided in o sec o s and use
di e en channels o concu en da a ansmissions in
he SM-MAC p o ocol. The e o e, s a ions in he SM-
MAC p o ocol ha e a highe packe deli e y a io han
he IEEE 802.11ah p o ocol when he e is he same
o al numbe o s a ions in he ne wo k.
Fig. 13: Th oughpu e sus he numbe o s a ions.
Fig. 13 shows a compa ison o he h oughpu o
he SM-MAC p o ocol and he MAC p o ocol in IEEE
802.11ah acco ding o he numbe o s a ions. The
h oughpu o bo h p o ocols dec eases as he num-
be o s a ions inc eases. In he SM-MAC p o ocol,
all s a ions in he ne wo k a e di ided by sec o s and
hen g ouped in o each RAW slo . This segmen a ion
educes con en ion when s a ions compe e o exchange
da a wi h Fo wa de s, esul ing in a highe p obabili y
o success. Addi ionally, up o eigh channels a e used
concu en ly o da a ansmissions, u he boos ing
©2025 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 112
Duc Ngoc Minh DANG e al. VOLUME: 23 |NUMBER: 2 |2025 |JUNE
Tab. 2: MAC pa ame e s
Pa ame e s Value Pa ame e s Value
Da a a e on s0.65 Mbps Da a a e on a26 Mbps
TP LCP 20 µs MAC Heade 224 bi s
[CWmin, CWmax][16, 1024] PS-POLL 20 by es
RTS 20 by es ACK 14 by es
CTS 14 by es Payload 128 by es
Slo ime σ52 µs SIFS 160 µs
P opaga ion ime δ1µs DIFS 264 µs
he o e all sys em h oughpu o he SM-MAC p o o-
col compa ed o he IEEE 802.11ah p o ocol.
Fig. 14: Ene gy e iciency e sus he numbe o s a ions.
Fig. 14 illus a es he ene gy e iciency o he SM-
MAC and IEEE 802.11ah p o ocols acco ding o he
numbe o s a ions. Ene gy e iciency is de ined as he
a io be ween o al h oughpu and o al ene gy con-
sump ion o he sys em. The ene gy e iciency o bo h
p o ocols dec eases as he numbe o s a ions inc eases.
As he numbe o s a ions inc eases, he p obabili y
o collision inc eases, leading o inc eased ene gy con-
sump ion o success ul da a ansmission. Th ough-
pu dec eases and ene gy consump ion inc eases as he
numbe o s a ions inc eases, leading o educed en-
e gy e iciency. Howe e , he SM-MAC p o ocol o e s
a no able ad an age o e he IEEE 802.11ah p o ocol.
I suppo s simul aneous da a ansmission on eigh
channels, he eby educing collision p obabili ies, in-
c easing success ul da a packe ansmissions, and ul-
ima ely consuming less ene gy. Consequen ly, he en-
e gy e iciency o he SM-MAC p o ocol su passes ha
o he IEEE 802.11ah p o ocol.
6.2. Pe o mance compa ison e sus
he numbe o RAW slo s
This sec ion p esen s a compa ison o he pe o mance
o he SM-MAC p o ocol and IEEE 802.11ah p o ocol
when changing he numbe o RAW slo s while ixing
he numbe o s a ions a 800 s a ions. The numbe o
RAW slo s is changed om 5 slo s o 50 slo s. Analy -
ical esul s a e deno ed “-ana”, while simula ion esul s
a e deno ed “-sim” in he igu e.
Fig. 15: Packe deli e y a io e sus he numbe o RAW slo s.
Fig. 15 shows he p obabili y o success ul packe
ansmission o he wo p o ocols SM-MAC and IEEE
802.11ah as he numbe o RAW slo s changes. Bo h
p o ocols exhibi an inc easing p obabili y o success-
ul ansmission wi h a highe numbe o RAW slo s.
When he numbe o RAW slo s inc eases, he numbe
o s a ions in each slo will dec ease, and he p oba-
bili y o collision be ween s a ions in he same RAW
slo will dec ease. Consequen ly, he packe deli e y
a io inc eases as he numbe o RAW slo s inc eases.
The SM-MAC p o ocol u he educes collision p ob-
abili ies by di iding he collision domain, enhancing
success ul ansmission p obabili y. This explains why
he SM-MAC p o ocol consis en ly achie es a highe
packe deli e y a io han he IEEE 802.11ah p o ocol
when he numbe o RAW slo s inc eases.
The h oughpu o bo h SM-MAC and IEEE
802.11ah p o ocols acco ding o he numbe o RAW
slo s is depic ed in Fig. 16. The h oughpu o bo h
p o ocols is ela i ely s able and is no a ec ed by
changing he numbe o RAW slo s. Howe e , i is
wo h no ing ha he SM-MAC p o ocol enjoys an ad-
©2025 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 113
