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IETE Journal of Research
ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/tijr20
Downlink NOMA Based Transmission Protocol
for Performance Improvement in Time-Varying
Wireless Network
Debbarni Sarkar & Yaka Bulo
To cite this article: Debbarni Sarkar & Yaka Bulo (2022): Downlink NOMA Based Transmission
Protocol for Performance Improvement in Time-Varying Wireless Network, IETE Journal of
Research, DOI: 10.1080/03772063.2022.2048710
To link to this article: https://doi.org/10.1080/03772063.2022.2048710
Published online: 21 Mar 2022.
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IETE JOURNAL OF RESEARCH
https://doi.org/10.1080/03772063.2022.2048710
Downlink NOMA Based Transmission Protocol for Performance Improvement in
Time-Varying Wireless Network
Debbarni Sarkar and Yaka Bulo
Department of Electronics and Communication Engineering, National Institute of Technology, Arunachal Pradesh, India
ABSTRACT
In this research work, the authors proposed an error constrained data transmission approach using
non-orthogonal multiple access (NOMA) protocol with hybrid automatic repeat request (HARQ) and
different packet combining schemes. In this proposed work, the transmitter simultaneously trans-
mits two data packets to the users (UEs) by considering the superposition coding technique in the
power domain. The decoding scheme of the receiver changes according to the message decoding
status in the previous rounds. This combined protocol has the capability of realizing ultra-reliability,
error correction power in high error prone wireless links. The receiver adopts successive interference
cancelation (SIC) to decode its own packet. Retransmission process is performed when the data is
erroneously received by the destination and the receiver corrects the error by applying HARQ with
Packet Combining (HARQ-PC) and HARQ with Aggressive Packet Combining (HARQ-APC) schemes.
This paper analyzes the data rates, outage probabilities and bit error rates of UEs for downlink NOMA
systems with respect to the transmit power using some basic parameters. The proposed schemes by
the authors can greatly outperform the conventional NOMA with HARQ (NOMA-HARQ) in terms of
data rates, outage probability and bit error rate in dynamic wireless channels.
KEYWORDS
Acknowledgement (ACK);
aggressive packet combining
(APC); bit error rate; hybrid
automatic repeat request
(HARQ); negative ACK
(NACK); non-orthogonal
multiple access (NOMA);
outage probability; packet
combining (PC); transmit
power
1. INTRODUCTION
Errorless data transmission and error correction are
the two important aspects in data communication net-
works since time immemorial. These aspects are some of
the challenging issues in wireless communication, espe-
cially in the dynamic wireless channel. Extensive research
workshavebeendoneearliertomitigatetheseproblems
considering orthogonal multiple access techniques. Some
of the important protocols which deal with error correc-
tion at the receiver end and which are widely researched
are Chakraborty’s Packet Combing (PC) [1–3]scheme.
Chakraborty et al. suggested a very simple and ele-
gant technique called Packet Combining (PC) scheme
for error correction at the receiver end. This is one of
the eminent schemes in this eld. Variation of PC tech-
nique has been found in many literatures [4–8]. Major-
ity packet combining (MjPC) scheme is the modied
concept of PC [9]. Aggressive Packet Combining (APC)
scheme is another variation of PC and this was pro-
posed by Leung [10] for faster error control and reduc-
ing latency in wireless data communication. Recently,
NOMAhasbeengravingattentionasaverypromising
multiple access technique and is considered a potential
eld of research. Till date many research works have been
carried out where dierent data transmission schemes
such as HARQ [11–21] were incorporated with NOMA
toachievelow-complexityuser(UE)pairingschemesand
to reduce the receiver. Throughout our literature sur-
vey, we could not nd a paper that incorporated HARQ
along with other advanced data transmission schemes in
NOMA to deal with reliability issues. Therefore, through
this paper, we proposed an error constrained data trans-
mission approach using non-orthogonal multiple access
(NOMA) protocol with hybrid automatic repeat request
(HARQ) and dierent packet combining schemes.
1.1 Related Work
The LTE, Internet of Things (IoT), ultra-dense hetero-
geneous networks (HetNets), 5G and beyond 5G, are
the various explorative elds where NOMA has been
applied [22–28]. The concept of NOMA can be dif-
ferentiable from Orthogonal Multiple Access (OMA)
as every UE can operate in the same frequency band
simultaneously. Power-domain and code-domain are the
main techniques in NOMA. Usually, the power-domain
NOMA distinguishes the UEs with the help of power
levels whereas, in the code-domain NOMA, dierent
codes are used to separate the UEs. The transmitter
mostly adopts superposition coding and the receiver uses
SIC [29] to retrieve the desired data packet through
decoding. The NOMA assigns more power to the UE
© 2022 IETE
2 D. SARKAR AND Y. BULO: DOWNLINK NOMA BASED TRANSMISSION PROTOCOL
located farther from the BS and less power is allocated
to the user closer to the BS. The utilization of spectrums
which are generated by their simultaneous transmission
fromthesamesourcetomultiplereceiversismain-
tained in NOMA [28,30]. One of the main advantages
of NOMA is that it can integrate with other potential
5G techniques to fulll the challenging task of quality of
service (QoS) [30,31]. Various fundamental results have
been presented to determine the ultimate performance
of NOMA in both the downlink (DL) [32–36]andthe
uplink (UL) [35–38]. In case of the downlink NOMA, the
base station superimposes all information waveforms of
itsusersandtheneachUE’sequipmentappliestheSIC
to detect their own packets. The idea in case of uplink
NOMAisjusttheoppositeasthebasestationemploys
SIC instead of UEs to distinguish the UEs’ data packets.
The error propagation may cause a disturbing eect
on the demodulation process of the UEs because of
which the UEs may fail to decode their data pack-
ets correctly [39,40]. To overcome such shortcomings
and to achieve reliable communication in the NOMA
system, various data transmission methods have been
incorporated [41].Extensiveresearcheshavedonein
thepasttoimplementdierentARQ(AutomaticRepeat
Request) techniques [42–45] with various modications
to enhance the performance of networks. Basically, in the
ARQ technique, a feedback message is sent to the trans-
mitter to inform whether retransmission is required or
not [45–48]. Usually, the erroneous data packet is dis-
carded and a retransmission is requested in ARQ. The
process is continued until the receiver gets error free
data packet. This time consuming process was modied
and named HARQ which performs based on the for-
ward error correction (FEC) at the physical layer and
the ARQ at the link layer [49]. In the HARQ technique,
an erroneous data packet is stored at the receiver and
a retransmission is requested. Even if the retransmis-
sion is incorrect, the receiver combines the two or more
erroneous data packets to obtain the original data pack-
ets. Among various NOMA with HARQ techniques, a
cooperative HARQ-assisted NOMA scheme [40]pro-
videsaninterference-awareoptimaldesigntoobtain
better system throughput. The author in [50]imple-
mented a NOMA scheme with truncated HARQ which
outperforms the conventional HARQ scheme. Authors
in [51] proposed a retransmission strategy for the uplink
NOMA, in which retransmitted data packets and the
original data packet share the same radio resources and
result in obtaining signicant latency reduction. Because
of this, it becomes a suitable retransmission technique
for URLLC. The work in [52]implementedafancy
retransmission scheme for two UEs in the downlink
NOMA employing HARQ that can adjust the power level
of users in the retransmission stage to reduce the num-
ber of attempts. The performance result of this approach
shows the increment of cell throughput. The authors
in [53] investigate the outage performance of HARQ
with chase combining assisted downlink NOMA systems.
The authors show that the performance of the UEs with
less transmit power can be improved eciently by using
HARQ-CC. The authors in [54] derived the expressions
for the outage probability, asymptotic outage probabil-
ity and throughput for both strong and weak UEs in
a device-to-device cooperative (D2D) downlink NOMA
network and xed gain amplify-and-forward (AF) relay-
ing network by assuming Nakagami-m fading D2D com-
munication links. The paper [55] derived an eective
absolute limit on the probability for successful packet
transmission for users in a buer-aided xed gain AF
relaying using NOMA network and use an Markov chain
(MC)basedapproachtocalculatetheoutageprobability
where the strong user acts as a relay for the weak user of
destination part. This paper also compares non-buer-
aided and buer-aided relaying systems. It demonstrates
that a buer-aided relaying system outperforms in terms
of outage probability.
1.2 Motivations and Challenges
Low outage probability is a very important aspect of the
wirelessnetworkasitprovidesreliabledatatransmission
andtoachievethis,thenetworkneedsahighdatarate
of the UE. To achieve low outage probability, we need to
obtain high signal to interference & noise ratio (SINR)
as the relationship between SINR and the outage prob-
ability is reciprocal in nature. Till date many research
works have been carried out where dierent data trans-
mission schemes such as HARQ [11–21]wereincorpo-
rated with NOMA to achieve low-complexity UE pairing
schemes and to reduce the receiver complexity. Through-
outourliteraturesurvey,wecouldnotndapaper
that incorporated HARQ along with other advanced data
transmission schemes in NOMA to deal with reliability
issues. Therefore, adopting various advanced data trans-
mission schemes smartly based on the feedback mes-
sages received from the receivers can be a new area to
exploretoimprovetheachievabledatarate,outageprob-
ability and reduce the bit error rate of the paired UEs.
Through this paper, we proposed an error constrained
data transmission approach using non-orthogonal mul-
tiple access (NOMA) protocol with hybrid automatic
repeat request (HARQ) and dierent packet combining
schemes.
D. SARKAR AND Y. BULO: DOWNLINK NOMA BASED TRANSMISSION PROTOCOL 3
1.3 Contributions
In this paper, we take steps towards understanding the
performance of two users in the downlink NOMA with
HARQ. The main contributions of the paper are as fol-
lows.
ItisworthmentioningherethatNOMAisfacedwith
error propagation problems where, if the receiver fails
to decode a signal, its interference aects the decod-
ing probability of all remaining signals which should be
decoded sequentially. Because of this, there is a high
chance of retransmission request from the receiver side
to get the original packet. HARQ based retransmission
was suggested in many of the literatures [11–21]butthese
schemes require large overhead in terms of parity bits
which causes receiver complexity which may lead to high
latency. Also, one of the unique properties of NOMA
is that it gives a chance to improve the performance of
paired UEs during HARQ-based data transmissions if
the transmission parameters and the decoding schemes
are adapted smartly. Therefore, taking these reasons as a
motivation, we have proposed an error constrained and
lowlatencyNOMA-HARQwithadvanceddatatransmis-
sionschemesviz.PCandAPCschemeforthedown-
link NOMA. Here, we have considered two users (UEs).
These schemes are also valid for an arbitrary number of
active users and uplink NOMA. In these proposed strate-
gies, advanced data transmission schemes viz. PC and
APCschemesareadaptedaccordinglyalongwithHARQ
based on the feedback messages received. Receivers uti-
lize erroneous data received to obtain the original packet.
In this paper, we assumed binary feedback messages
namely acknowledgment (ACK) and negative- acknowl-
edgment (NACK) as usual in HARQ protocols.
Using these schemes, data rate, outage probability and bit
errorrateforeachUEareanalyzed.
Simulation results show that the proposed schemes can
achieve signicant outcomes as compared to the conven-
tional NOMA-HARQ.
1.4 Outline
The rest of this paper is structured as follows. Section
2 describes the background study. In Section 3, the
system model of conventional NOMA-HARQ is intro-
duced, the basic NOMA performance parameters, such
as data rates, outage probability, and user bit error rates,
are determined in Section 4. We have also elaborated
and explained the simulation results of these proposed
schemes in Section 5. Finally, in Section 6, the proposed
Tab le 1: Parameters used
Parameter Parameter value
σ2−65dB
d1,d2800m, 200m
N1000
η2.5
α11,α12 ,α13,
α21,α22 ,α23
0.75, 0.8, 0.85,
0.25, 0.20, 0.15
R1,R21bit/slot/Hz,
work is concluded with some observations. In addition to
this, Table 1provides the values of basic parameters.
2. BACKGROUND STUDY
2.1 Review of Conventional PC Scheme
PC scheme is a simple technique where the receiver
can correct a limited number of errors like one or two
bits errors from the received erroneous copies. In this
scheme [56], the receiver does binary EXOR operation
betweentwoerroneouscopiesofthedatapacket(i.e. rst
istransmittedcopythatisstoredinabuer&secondone
is retransmitted copy) to obtain the positions of the errors
inthedatapacketwhenatleastanerroroccursinthe
dierentbitlocationoftheerroneouscopiesinthedata
packet. Then the receiver can apply the brute method to
correcttheerrorsbychanging“1”to“0”orviceversa.
The basic operation of the PC scheme is explained in
example 1.
Example 1: Say transmitter sends data packet “11110011” (original copy) to the
receiver.
Transmitter Receiver
Transmitted Copy: 11110011 First copy: 11100011(error is
on the fourth bit
from left)
Retransmitted
Copy:
11110011 Second Copy: 11010011(error is
on the third bit
from left)
EXOR Operation: 00110000 (errors’
locations are in
the third bit and
the fourth bit
from left)
In this example, locations of the errors of the combined
data packet are in the third bit and/or fourth bit from left.
After applying the conventional brute method we usually
obtain the corrected copy.
The main limitation of the PC scheme is that it can’t
detect the location of an error when the error is present
at the same bit location of two copies of the data packet.
Example 2 illustrates the drawback of this technique.
4 D. SARKAR AND Y. BULO: DOWNLINK NOMA BASED TRANSMISSION PROTOCOL
Example 2: Say transmitter sends data packet “11010111” (original copy) to the
receiver.
Transmitter Receiver
Transmitted Copy: 11010111 First copy: 11110111 (error is
on the third bit
from left)
Retransmitted
Copy:
11010111 Second Copy: 11110111 (error is
on the third bit
from left)
EXOR Operation: 00000000(error’s
location are not
identified)
In this case, correction is not possible as an error is
presentatthesamebitlocationoftwocopiesofthedata
packet.
2.2 Review of Conventional APC Scheme
The APC scheme overcomes the above mentioned lim-
itations of the PC scheme. It is an extension of the
PC scheme that performs bit-by-bit majority voting on
the received erroneous copies. The steps of this APC
scheme [57] can be represented as follows:
IntheAPCschemefollowingstepsareperformed:
Step 1: In the APC scheme, the sender retransmits two
copiesofthedatapacketifthersttransmittedcopyisnot
errorless. The receiver detects errors in the retransmitted
copies of the data packet and if both are also found to be
erroneous, the receiver performs bitwise majority voting
operation on those three received erroneous copies (one
of them is the transmitted copy and the remaining are
retransmittedcopies)toobtainacombineddatapacket.
Againthereceiverndsouterrorsinthecombineddata
packet.
Step 2: This step is required to nd the least reliable
bits using bit-by-bit majority voting if the combined data
packet is found to be erroneous.
Step 3: In this step, the receiver nds out all the correct bit
patterns from the least reliable bits to get a correct copy
of the data packet. These possible correct bit patterns can
be obtained from 2l−1where“l”isthenumberofleast
reliable bits. APC scheme is illustrated with an example as
follows:
In this example, the original copy of the data packet is
obtained from the combined data packet. The receiver
could recover the original copy by using step 1.
In this example the combined data packet is found to be
erroneousthatiswhythereisaneedtondtheleast
Example 1: Say transmitter sends data packet “11110011” (original copy) to the
receiver.
Transmitter Receiver
Transmitted Copy: 11110011 First copy: 11100011(error is
on the fourth bit
from left)
Retransmitted
Copy:
11110011 Second Copy: 11010011(error is
on the third bit
from left)
Retransmitted
Copy:
11110011 Third Copy: 11110010(error is
on the eighth bit
from left)
Majority Logic: 11110011
(combined
packet)
Example 2: Suppose a transmitter sends data packet “11111000” to a receiver.
Transmitter Receiver
Transmitted Copy: 11111000 First copy: 11111010 (error is
on the seventh
bit from left)
Retransmitted
Copy:
11111000 Second Copy: 11111001(error is
on the eighth bit
from left)
Retransmitted
Copy:
11111000 Third Copy: 11011000 (error is
on the third bit
from left)
Majority Logic: 11011000
(combined
packet)
reliable bits. The third, senenth and eighth bits from the
left are identied as the least reliable bits and the possible
correct bit patterns may be 001,010, 011, 100, 101,110 or
111. These patterns are used to get the corrected copies.
3. SYSTEM MODEL
We represent a time varying network with a downlink
broadcast scenario where two users want to connect with
the access point (AP) with widely dierent channel quali-
ties,assumeoneuser(UE)atthecellcenter(neartheAP)
and another user (UE) the cell edge (far from AP) which
are denoted by UE2and UE1,respectively.
3.1 Conventional NOMA-HARQ Scheme
In a two user (UE) downlink NOMA system, the AP
without taking advantage of multiple antennas transmits
a superposition coded data packet ssimultaneously to
UE1and UE2.
s=√P√α1s1+√α2s2(1)
where s1and s2aredesireddatapacketsforUE
i,i=1,
2andPis the total transmit power.α1,α2are the power
allocation factors of UEi,i=1, 2 where α1+α2=1;
α1≥α2.Afterpropagatingthroughthechannelhi,i=1,
D. SARKAR AND Y. BULO: DOWNLINK NOMA BASED TRANSMISSION PROTOCOL 5
2, the copy of sis received by UEi,i=1, 2.Received data
packet by UEi,i=1, 2 for conventional NOMA-HARQ
is
yi=his+ni(2)
where nidenotes additive white Gaussian noise (AWGN)
with zero mean and variance σ2
n,hi=d−η
i(randn
(1, N)+1i∗randn(1, N))/√2Herediis the distance
between AP to UEi,i=1, 2 and ηis called the path loss
exponent. Nrepresents the number of bits transmitted
per packet.
The copy received by the UE1can be written as follows:
y1=h1√P√α1s1+√P√α2s2+n1(3)
The received copy by the UE2is written as follows:
y2=h2√P√α1s1+√P√α2s2+n2(4)
It is expected that the channel gain of UE2(h2)is greater
than the channel gain of UE1(h1),|h2|2
σ2>|h1|2
σ2as UE2is
closer to the AP than UE1.SincetheUE
2has better chan-
nel condition as compared to UE1,UE
2rst decodes and
cancels data packet s1by considering SIC, to obtain its
own data packet s2.However,UE
1directly decodes its
own data packet s1by treating UE2’s data packet s2as
interference.
In conventional NOMA, the SINR and the achieved data
rate of UE1for decoding s1can be expressed as:
γ1→1=|h1|2Pα1
|h1|2Pα2+σ2(5)
R1→1=log21+|h1|2Pα1
|h1|2Pα2+σ2(6)
where the occurrence term Pα2in the denominator is due
to the UE2’s data packet treated as Gaussian noise.
The SINR and the achieved data rate of UE2for decoding
s1can be written as:
γ2→1=|h2|2Pα1
|h2|2Pα2+σ2(7)
R2→1=log21+|h2|2Pα1
|h2|2Pα2+σ2(8)
UE2is able to decode its own data packet s2by perfectly
eliminating the interfering data packet s1via SIC. The
SINR and the achieved data rate of UE2for decoding s2
can be represented as:
γ2→2=|h2|2Pα2
σ2(9)
R2→2=log21+|h2|2Pα2
σ2(10)
According to Shannon’s information theory, the
outage event occurs when the rate of UE is less than
the data packet transmission rate (bits/Hz). The out-
age event occurs when UE1cannot demodulate its data
packet correctly. The outage probability, PO,1 of UE1can
be obtained as:
PO,1 =Pr{R1→1<R1}
=1−Pr{R1→1>R1}
=1−Pr log21+|h1|2Pα1
|h1|2Pα2+σ2>R1
=1−e−(δ1)
(11)
where δ1=(2R1−1)σ2
Pα1−(2R1−1)Pα2,Pα1−(2R1−1)Pα2>0.
TheoutageeventmayoccurforUE
2, if UE2fails to
either subtract the interfering data packet s1or recover
its own data packet. The outage probability, PO,2 of UE2
is represented as:
PO,2 =Pr{R2→2<R2,R2→1<R1}
=1−Pr{R2→2>R2,R2→1>R1}
=1−Pr ⎧
⎨
⎩
log21+|h2|2Pα2
σ2>R2,
log21+|h2|2Pα1
|h2|2Pα2+σ2>R1⎫
⎬
⎭
=1−e−(max{δ1,δ2})
(12)
where δ1=(2R1−1)σ2
Pα1−(2R1−1)Pα2,Pα1−(2R1−1)Pα2>0,
δ2=(2R2−1)σ 2
Pα2.
We calculate the bit error rate at the UE1and the UE2,
assuming Binary phase-shift keying (BPSK) data pack-
ets are used for both the UEs. In BPSK modulation the
bit error rate for UE1in NOMA can be represented as
follows:
ε1=Q2∗γ1→1
=Q⎛
⎝
2∗|h1|2Pα1
|h1|2Pα2+σ2⎞
⎠(13)
The bit error rate for UE2in the NOMA scheme can be
expressed as follows
ε2=Q2∗γ2→2
6 D. SARKAR AND Y. BULO: DOWNLINK NOMA BASED TRANSMISSION PROTOCOL
=Q⎛
⎝
2∗|h2|2α2P
σ2⎞
⎠(14)
3.2 Proposed Schemes
To improve the performance of UEs in downlink
NOMA,wehaveproposedanerrorconstrainedandlow
latency NOMA-HARQ with advanced data transmission
schemesnamelyPCandAPCscheme.Adaptingvarious
advanced data transmission schemes smartly based on
the feedback messages received from the UEs can sig-
nicantly improve the performance of the UEs at the
receivingend.InNOMA-HARQwithPCscheme,UEs
of NOMA store an erroneously received copy at the
buer and request for retransmission to AP. After one
retransmission, UEs perform a logical EXOR operation
between the retransmitted erroneous copy of the data
packet and the original erroneous copy of the data packet
to locate the bit error position. In NOMA-HARQ with
the APC scheme, AP retransmits two original message
copiesofthepacketwhenUEsrequestforretransmission.
The majority logic is applied bit-to-bit on three message
copies of the packet where the rst copy is erroneous
transmitted copies of the packet which is stored in a
buer and the other two copies are erroneous retransmit-
ted copies of the packet. The operation of the proposed
schemes can be understood more clearly by the ow
diagram shown in Figure 1.
The AP transmits a copy of the superposition coded data
packet Sto UE1,UE
2.UE
1decodes the data packet s1and
UE2decodes the data packet s2from the superposition
coded data packetS. They perform error detection oper-
ations individually on the received data packets, s1,s2and
send ACKs to AP for transmission of a new data packet
if detection operation is performed correctly otherwise
UE1, UE2buer the received erroneous data packets s1,s2
as the rst copies and they request for retransmission of
theothercopiesbysendingNACKtotheAP.Onreceiv-
ing NACKs, AP retransmits another copy of the superpo-
sition coded data packet S.TheUE
1, UE2,onreceiving
the retransmitted second copies, s
1,s
2,checkthepresence
of errors on the second copies, if they are found to be
erroneous, the UE1, UE2individually applies PC scheme
using rst and second copies as mentioned above and if
thecorrectcopiesarenotretrievedbythePCscheme,
the UE1, UE2buerboththerstandsecondreceived
erroneous copies, and each UE requests for retransmis-
sion of the third copy of that superposition copies of the
coded data packet Sto the UEs. The UE1and UE2on
receiving the third copies perform error detection. If the
copies s
1,s
2are detected without error, UE1and UE2
accept the correct copies and they discard the incorrect
copies including the previously buered copies and send
ACKs to AP for transmission of a new data packet. For
erroneous third copies s
1,s
2, the APC scheme is applied
to three stored copies in the buer. UE1and UE2suc-
cessfully retrieve the correct copies s1,s2by APC scheme
and send ACKs to the AP for transmission of the new
data packet. But if the APC scheme fails, the receiver
sends NACK to AP, UE1and UE2fail to get their correct
data packet and repeat the initial process again. The fol-
lowing subsections present numerical derivations of the
proposed schemes.
3.3 Proposed NOMA-HARQ with PC Scheme
In NOMA-HARQ with PC scheme, copy of superposi-
tioncodeddatapacketistransmittedthroughachan-
nel hiK for K-thHARQroundstoUE
i,i=1, 2 and
the power allocation factors of UEi,i=1, 2 for HARQ
rounds.
The combined received copy of UE1can be represented
as follows:
yPC
1,K=
K
k=1
h1k√P√α1Ks1+√P√α2ks2+n1;K=2
(15)
In case of UE2, the combined received copy becomes:
yPC
2,K=
K
k=1
h2k√P√α1ks1+√P√α2ks2+n1;K=2
(16)
When UE1demodulates its own data packet after K-th
HARQ rounds, the SINR can be written as:
γPC
K,1→1=
K
k=1
|h1k|2Pα1k
|h1k|2Pα2k+σ2;K=2 (17)
The achieved data rate of UE1for decoding s1after K-th
HARQ rounds where K=2canbeexpressedas:
RPC
2,1→1=log21+
2
k=1
|h1k|2Pα1k
|h1k|2Pα2k+σ2(18)
where the occurrence term Pα2kin the denominator is
due to the UE2’s data packet is treated as Gaussian noise.
D. SARKAR AND Y. BULO: DOWNLINK NOMA BASED TRANSMISSION PROTOCOL 7
Figure 1: Flow chart of UE1,UE
2data transmission process
8 D. SARKAR AND Y. BULO: DOWNLINK NOMA BASED TRANSMISSION PROTOCOL
In NOMA-HARQ with PC scheme when UE2demodu-
lates s1, the SINR is written as:
γPC
2,2→1=
2
k=1
|h2k|2Pα1k
|h2k|2Pα2k+σ2(19)
The achieved data rate of UE2for decoding s1can be
written as follows:
RPC
2,2→1=log21+
2
k=1
|h2k|2Pα1k
|h2k|2Pα2k+σ2(20)
where the occurrence of the term Pα2kin the denomina-
tor is due to the UE2’s data packet and is considered as
Gaussian noise while decoding s1.
The SINR can be written as when UE2demodulates s2
γPC
2,2→2=
2
k=1
|h2k|2Pα2k
σ2(21)
Accordingly, the achieved rate of UE2for decoding its
owndatapackets2is given by
RPC
2,2→2=log21+
2
k=1
|h2k|2Pα2k
σ2(22)
3.4 Proposed NOMA-HARQ with APC Scheme
In NOMA-HARQ with APC scheme, after K-thHARQ
rounds combined copy of the data packet received at the
UE1is:
yAPC
1,K=
K
k=1
h1k√P√α1ks1+√P√α2ks2+n1;K=3
(23)
The combined received copy at the UE2is:
yAPC
2,K=
K
k=1
h2k√P√α1ks1+√P√α2ks2+n2;K=3
(24)
In NOMA-HARQ with APC scheme, when UE1demod-
ulates its own data packet after K- th HARQ rounds, the
SINR can be written as:
γAPC
K,1→1=
K
k=1
|h1k|2Pα1k
|h1k|2Pα2k+σ2;K=3 (25)
The achieved data rate of UE1for decoding s1after K-th
HARQ rounds where K=3canbeexpressedas:
RAPC
3,1→1=log21+
3
k=1
|h1k|2Pα1k
|h1k|2Pα2k+σ2(26)
where the occurrence term Pα2kin the denominator is
due to the UE1’s data packet and is treated as Gaussian
noise.
In NOMA-HARQ with APC scheme, when UE2demod-
ulates data packet s1, the SINR can be written as:
γAPC
3,2→1=
3
k=1
|h2k|2Pα1k
|h2k|2Pα2k+σ2(27)
The achieved data rate of UE2for decoding data packet
s1is expressed as follows:
RAPC
3,2→1=log21+
3
k=1
|h2k|2Pα1k
|h2k|2Pα2k+σ2(28)
where the occurrence of the term Pα2kin the denomi-
nator is due to the UE2’s data packet and is treated as
Gaussian noise while decoding s1.
UE2demodulates data packet s2,sotheSINRcanbe
written as:
γAPC
3,2→2=
3
k=1
|h2k|2Pα2k
σ2(29)
Accordingly, the achieved data rate of UE2for decoding
its own data packet s2is given by:
RAPC
3,2→2=log21+
3
k=1
|h2k|2Pα2k
σ2(30)
4. PERFORMANCE ANALYSIS OF THE PROPOSED
SCHEME
In this paragraph, we derive the expressions of the out-
ageprobability,biterrorrateofeachUEwithrespectto
PC and APC schemes in downlink NOMA system for
oering further insights into system performance.
Outage probabilities of NOMA-HARQ with PC
scheme for UEi,i=1, 2:
When UE1cannot demodulate its message correctly, a
NACK is sent back to AP to request for retransmission
D. SARKAR AND Y. BULO: DOWNLINK NOMA BASED TRANSMISSION PROTOCOL 9
until UE1demodulates its message correctly or the num-
ber of retransmission rounds reaches upto K.Theoutage
event occurs when UE1cannot demodulate its message
correctly after K- th transmission rounds. The outage
probability PPC
O,1,Kof UE1,canbeobtainedas:
PPC
O,1,K=Pr{RPC
K,1→1<R1};K=2
PPC
O,1,2 =1−Pr{RPC
2,1→1>R1}
=1−Pr log21+
2
k=1
|h1k|2Pα1k
|h1k|2Pα2k+σ2>R1
=1−Pr 2
k=1
|h1k|2Pα1k
|h1k|2Pα2k+σ2>2R1−1(1)
After some mathematical calculations, outage probability
expression can be written as:
PPC
O,1,2 =1−
1
l=0
(δPC
1,2 )l1
l!e−δPC
1,2 (31)
where δPC
1,2 =
2
k=1
(2R1−1)σ 2
Pα1k−(2R1−1)Pα2k,
2
k=1
Pα1k−(2R1−1)
Pα2k>0.
The outage event may occur for UE2, if UE2fails to either
subtract the interfering message s1or recover its own
message after K- th transmission rounds. The outage
probability PPC
O,2,Kof UE2, can be obtained as follows:
PPC
O,2,K=Pr{RPC
K,2→2<R2,RPC
K,2→1<R1};K=2
PPC
O,2,2 =1−Pr{RPC
2,2→2>R2,RPC
2,2→1>R1}
=1−Pr ⎧
⎪
⎪
⎪
⎪
⎨
⎪
⎪
⎪
⎪
⎩
log21+
2
k=1
|h2k|2Pα2k
σ2>R2,
log21+
2
k=1
|h2k|2Pα1k
|h2k|2Pα2k+σ2>R1
⎫
⎪
⎪
⎪
⎪
⎬
⎪
⎪
⎪
⎪
⎭
=1−Pr ⎧
⎪
⎪
⎪
⎪
⎨
⎪
⎪
⎪
⎪
⎩
2
k=1
|h2k|2Pα2k
σ2>2R2−1,
2
k=1
|h2k|2Pα1k
|h2k|2Pα2k+σ2>2R1−1
⎫
⎪
⎪
⎪
⎪
⎬
⎪
⎪
⎪
⎪
⎭
(2)
The outage probability expression after some mathemat-
ical calculation can be written as:
PPC
O,2,2 =1−1
l=0
max {δPC
1,2 ,δPC
2,2 }l1
l!e−max{δPC
1,2 ,δPC
2,2 }
(32)
where δPC
1,2 =
2
k=1
(2R1−1)σ 2
Pα1k−(2R1−1)Pα2k,δPC
2,2 =
2
k=1
(2R2−1)σ 2
Pα2k,
2
k=1
Pα1k−(2R1−1)Pα2k>0.
Outage probability of NOMA-HARQ with APC
scheme for UEi,i=1, 2:
In NOMA-HARQ with APC scheme, three transmitted
message copies of the packet are utilized for detecting
signals. The outage probability of UE1is given by:
PAPC
O,1,K=1−Pr{RAPC
K,1→1>R1};K=3
PAPC
O,1,3 =1−Pr 3
k=1
|h1k|2Pα1k
|h1k|2Pα2k+σ2>2R1−1
After some mathematical calculation, the outage proba-
bility expression can be written as:
PAPC
O,1,3 =1−
2
l=0
(δAPC
1,3 )l1
l!e−δAPC
1,3 (33)
where δAPC
1,3 =
3
k=1
(2R1−1)σ 2
Pα1k−(2R1−1)Pα2k,
3
k=1
Pα1k−(2R1−1)
Pα2k>0.
TheoutageprobabilityofUE
2is given by:
PAPC
O,2,3 =1−Pr ⎧
⎪
⎪
⎪
⎨
⎪
⎪
⎪
⎩
3
k=1
|h2k|2Pα2k
σ2>2R2−1,
3
k=1
|h2k|2Pα1k
|h2k|2Pα2k+σ2>2R1−1
⎫
⎪
⎪
⎪
⎬
⎪
⎪
⎪
⎭
After some mathematical calculation, the outage proba-
bility expression can be written as:
PAPC
O,2,3=1−2
l=0
max {δAPC
1,3 ,δAPC
2,3 }l1
l!e−max{δAPC
1,3 ,δAPC
2,3 }
(34)
where δAPC
1,3 =
3
k=1
(2R1−1)σ 2
Pα1k−(2R1−1)Pα2k,δAPC
2,3 =
3
k=1
(2R2−1)σ 2
Pα2k,
3
k=1
Pα1k−(2R1−1)Pα2k>0:
The cumulative distribution function (CDF) can be
expressed as follows:
Fi,K(x)=1−
K−1
k=0x
λik1
k!e−x
λi(35)
10 D. SARKAR AND Y. BULO: DOWNLINK NOMA BASED TRANSMISSION PROTOCOL
Bit error rate of NOMA-HARQ with PC scheme for
UEi,i=1, 2:
We calculate the bit error rate at the UE1,UE
2,and
assume BPSK signaling for both the UEs. In BPSK mod-
ulation, the bit error rate for UE1in NOMA-HARQ with
PC scheme after K-thHARQroundisrepresentedas
follows:
εPC
1,K=Q2∗γPC
K,1→1;K=2
εPC
1,2 =Q⎛
⎝
2∗2
k=1
|h1k|2Pα1k
|h1k|2Pα2k+σ2⎞
⎠(36)
In BPSK modulation the bit error rate for UE2in NOMA-
HARQ with PC scheme can be written as:
εPC
2,K=Q2∗γPC
K,2→2;K=2
εPC
2,2 =Q⎛
⎝
2∗2
k=1
|h2k|2Pα2k
σ2⎞
⎠(37)
Bit error rate of NOMA-HARQ with APC scheme for
UEi;i=1, 2:
In BPSK modulation the bit error rate for UE1in NOMA-
HARQ with APC scheme after K-th HARQ round is
written as:
εAPC
1,K=Q2∗γAPC
K,1→1;K=3
εAPC
1,3 =Q⎛
⎝
2∗3
k=1
|h1k|2Pα1k
|h1k|2Pα2k+σ2⎞
⎠(38)
In BPSK modulation the bit error rate for UE2in NOMA-
HARQ with APC scheme can be expressed as follows:
εAPC
2,K=Q2∗γAPC
K,2→2;K=3
εAPC
2,3 =Q⎛
⎝
2∗3
k=1
|h2k|2Pα2k
σ2⎞
⎠(39)
5. ANALYSIS OF SIMULATION RESULTS
This paragraph contains the simulation outcomes to get
the clear-sightedness of the recommended schemes. The
values of the main parameters those are used in simula-
tionaregiveninthefollowingTable1.
The suggested scheme’s performance is measured in
terms of data rate, outage probability and bit error rate
using Matlab R2014a computer simulation in window 7
platformonanIntelbasedcorei3having4GBRAM.In
this paper, we have compared the performance of Con-
ventional NOMA-HARQ, proposed NOMA-HARQ with
PC scheme and NOMA-HARQ with APC scheme for
Figure 2: The data rate of UE1(Far) against transmitting power Pin the Conventional NOMA-HARQ, proposed NOMA-HARQ with PC
scheme and NOMA-HARQ with APC scheme
D. SARKAR AND Y. BULO: DOWNLINK NOMA BASED TRANSMISSION PROTOCOL 11
each UE that is UE1and UE2in terms of data rate, outage
probability and bit error rate.
As shown in the simulation results, Figures 2and 3
showtheplotofthedatarateofUE
1(far UE) and UE2
(near UE), respectively against transmitting power for the
conventional NOMA-HARQ and our proposed schemes
namely NOMA-HARQ with PC scheme and NOMA-
HARQ with APC scheme. These simulation results are
evaluated based on the equations (6), (18) and (26) for
UE1. Similarly, equations (10), (22) and (30) are used
for UE2by considering the values of basic parameters
which are provided in Table 1. The transmitting power
Pfrom 0 to 60 (dBm) has been considered for each UE.
The data rates increment of UE1and UE2is much higher
for the proposed schemes in comparison to the conven-
tional NOMA-HARQ. At 60 dBm P,thedataratesofUE
1
are 1.38, 1.97 and 2.54 bps/Hz for Conventional NOMA-
HARQ, proposed NOMA-HARQ with PC scheme and
NOMA-HARQ with APC scheme, respectively. Similarly,
the data rates of UE2are 3.41, 4.16 and 4.66 bps/Hz for
Conventional NOMA-HARQ, proposed NOMA-HARQ
Figure 3: The data rate of UE2(Near) against transmitting power Pin the Conventional NOMA-HARQ, proposed NOMA-HARQ with PC
scheme and NOMA-HARQ with APC scheme
Figure 4: The outage probability of UE1against transmitting power Pin the Conventional NOMA-HARQ, proposed NOMA-HARQ with
PC scheme and NOMA-HARQ with APC scheme
12 D. SARKAR AND Y. BULO: DOWNLINK NOMA BASED TRANSMISSION PROTOCOL
Figure 5: The outage probability of UE2against transmitting power Pin the Conventional NOMA-HARQ, proposed NOMA-HARQ with
PC scheme and NOMA-HARQ with APC scheme
Figure 6: The bit error rate of UE1against transmitting power Pin the Conventional NOMA-HARQ, proposed NOMA-HARQ with PC and
NOMA-HARQ with APC scheme
with PC scheme and NOMA-HARQ with APC scheme,
respectively.Fromthese,wehaveobservedthatproposed
schemes (NOMA-HARQ with APC scheme and NOMA-
HARQ with PC scheme) provide higher data rate as
compared to conventional NOMA-HARQ for both UE1
and UE2andtheseplotsalsodescribethatUE
2obtains
higher data rates than UE1for all schemes as the distance
between AP and UE2is lesser than that of the UE1.
Figures 4and 5show the results of UE1and UE2’s in
terms of outage probability against P.Outageprobability
equations (11), (31) and (33) for UE1and (12), (32)
and (34) for UE2areconsideredtomodeltheresults.
We have assumed the data rates of UE1and UE2as
1 bits/slots/Hz. Pisvariedfrom0to60(dBm).Wecansee
in the gures that the Outage probabilities of both UEs
keep decreasing with increaseP. 33%, 17%, and 9% are
theoutageprobabilitiesofUE
1for Conventional NOMA-
HARQ, proposed NOMA-HARQ with PC scheme and
NOMA-HARQwithAPCscheme,respectively.Similarly
for UE2, the outage probabilities are 10%, 3% and 1% for
Conventional NOMA-HARQ, proposed NOMA-HARQ
D. SARKAR AND Y. BULO: DOWNLINK NOMA BASED TRANSMISSION PROTOCOL 13
Figure 7: The bit error rate of UE2against transmitting power in the Conventional NOMA-HARQ, proposed NOMA-HARQ with PC and
NOMA-HARQ with APC scheme
with PC scheme and NOMA-HARQ with APC scheme,
respectively where Pis 60 dBm. The results show that
for both the UEs, outage probability is much lower for
the proposed schemes as compared to the conventional
NOMA-HARQ.
The outcomes of UE1and UE2’s third experiment are
shown in Figures 6and 7.TheX-axis depicts Pin dBm
which also varies from 0 to 60 (dBm) while the Y-axis
reects the bit error rate. To estimate the outcomes for
UE1, equations (13), (36) and (38) are considered and for
UE2, equations (14), (37) and (39) are considered. Results
show that the bit error rates of UE1and UE2are gradu-
ally decreasing with the increment of Pfor all schemes.
The bit error rates of UE1are 3%, 0.7% and 0.08% for
conventional NOMA-HARQ, proposed NOMA-HARQ
withPCandproposedNOMA-HARQwithAPCscheme,
respectively and 0.4%, 0.03% and 0.00138% for Conven-
tional NOMA-HARQ, proposed NOMA-HARQ with PC
scheme and NOMA-HARQ with APC scheme, respec-
tively for UE2.Asseenintheabovecases,theproposed
schemes give better results as compared to the Con-
ventional NOMA-HARQ and out of these proposed
schemes, the NOMA-HARQ with APC scheme performs
best for both the UEs.
6. CONCLUSIONS
In this work, we have proposed an error constrained data
transmission approach using non-orthogonal multiple
access (NOMA) protocol with hybrid automatic repeat
request (HARQ) and dierent packet combining schemes.
Advanced data transmission techniques namely PC and
APC are adapted according to the feedback messages
received at the AP. As seen from simulation results, the
proposed schemes provide signicant results over con-
ventional NOMA-HARQ. In this paper, we implement
NOMA-HARQ with PC scheme and NOMA-HARQ
with APC scheme for downlink NOMA with two UEs.
Mathematical derivation of the data rate, outage prob-
ability and the bit error rate for each UE is done for
the conventional NOMA-HARQ, NOMA-HARQ with
PC scheme and NOMA-HARQ with APC scheme. The
NOMA-HARQ with PC and NOMA-HARQ with APC
schemes outperform the conventional NOMA-HARQ
scheme. In comparison to conventional NOMA-HARQ,
it has been observed that NOMA-HARQ with PC and
NOMA-HARQ with APC systems provide high data rate,
low outage probability and low bit error rate and among
these three schemes, NOMA-HARQ with APC scheme
proved to be the best. The analytical results obtained in
14 D. SARKAR AND Y. BULO: DOWNLINK NOMA BASED TRANSMISSION PROTOCOL
this work are also applicable to the case with an arbi-
trary number of UEs and also for up-link NOMA. The
proposed schemes achieved better results over the con-
ventional NOMA-HARQ.
ACKNOWLEDGEMENTS
We would like to thank Director Prof. Pinakeswar Mahanta
for his continuous support and careful guidance. Also, we are
highly grateful to NIT Arunachal Pradesh, where we could have
the environment to complete this work.
DISCLOSURE STATEMENT
No potential conict of interest was reported by the author(s).
REFERENCES
1. S. Chakraborty Shyam, E. Yli-Juuti, and M. Liinaharja,
“An ARQ scheme with packet combining,” IEEE Commun.
Lett., Vol. 2, no. 7, pp. 200–202, 1998.
2. S. Chakraborty Shyam, E. Yli-Juuti, and M. Liinaharja,
“An adaptive ARQ scheme with packet combining for
time varying channels,” IEEE Commun. Lett.,Vol.3,no.
2, pp. 52–54, 1999.
3. S. Chakraborty Shyam, and M. Liinaharja, “An exact anal-
ysisofanadaptiveGBNschemewithslidingobservation
interval mechanism,” IEEE Commun. Lett.,Vol.3,no.5,
pp. 151–153, 1999.
4. T. Bhunia Chandan. “Modied packet combining using
error forecasting decoding to control error,” in Third
International Conference on Information Technology and
Applications (ICITA’05), vol. 2. IEEE, 2005, pp. 641–646.
5. T. Bhunia Chandan. “Packet reversed packet combin-
ing scheme,” in 7th IEEE International Conference
on Computer and Information Technology. CIT, 2007,
pp. 447–451.
6. T. Bhunia Chandan. “Modied packet combining using
error forecasting decoding to control error,” in Third
International Conference on Information Technology and
Applications (ICITA’05), vol. 2. IEEE, 2005, pp. 641–646.
7. H. Dubois-Ferriere, D. Estrin, and M. Vetterli. “Packet
combining in sensor networks,” in Proceedings of the 3rd
international conference on Embedded networked sensor
systems, 2005, pp. 102–115.
8. L. Deng Sheng, X. Ming, and L. ShaoQian, “Packet com-
bining based on cross-packet coding,” Sci. China Inform.
Sci., Vol. 56, no. 2, pp. 1–10, 2013.
9. B. Wicker Stephen, “Adaptive rate error control through the
use of diversity combining and majority-logic decoding in
ahybrid-ARQprotocol,”IEEE Trans. Commun., Vol. 39,
no. 3, pp. 380–385, 1991.
10. Y.-W. Leung, “Aggressive packet combining for error con-
trol in wireless networks,” IEICE Trans. Commun., Vol. 83,
no. 2, pp. 380–385, 2000.
11. J. Choi, “On HARQ-IR for downlink NOMA systems,”
IEEE Trans.Commun., Vol. 64, no. 8, pp. 3576–3584, 2016.
12. D. Cai, Z. Ding, P. Fan, and Z. Yang, “On the performance
of NOMA with hybrid ARQ,” IEEE Trans. Veh. Technol.,
Vol. 67, no. 10, pp. 10033–10038, 2018.
13. Z. Shi, S. Ma, H. ElSawy, G. Yang, and M.-S. Alouini,
“Cooperative HARQ-assisted NOMA scheme in large-
scale D2D networks,” IEEE Trans. Commun., Vol. 66, no.
9, pp. 4286–4302, 2018.
14. Z. Xiang, W. Yang, G. Pan, Y. Cai, Y. Song, and Y. Zou,
“Secure transmission in HARQ-assisted non-orthogonal
multiple access networks,” IEEE Trans. Inf. Forensics Secur.,
Vol. 15, pp. 2171–2182, 2019.
15. Z. Xiang, W. Yang, Y. Cai, Z. Ding, and Y. Song, “Secure
transmission design in HARQ assisted cognitive NOMA
networks,” IEEE Trans. Inf. Forensics Secur., Vol. 15,
pp. 2528–2541, 2020.
16. Z. Shi, C. Zhang, Y. Fu, H. Wang, G. Yang, and S.
Ma, “Achievable diversity order of HARQ-aided downlink
NOMA systems,” IEEE Trans. Veh. Technol.,Vol.69,no.1,
pp. 471–487, 2019.
17. M. Ali, H. Tabassum, and E. Hossain, “Dynamic user
clustering and power allocation for uplink and downlink
non-orthogonal multiple access (NOMA) systems,” IEEE
Access, Vol. 4, pp. 6325–6343, 2016.
18. W. Liang, Z. Ding, Y. Li, and L. Song, “User pairing for
downlink non-orthogonal multiple access networks using
matching algorithm,” IEEE Trans. Commun., Vol. 65, no.
12, pp. 5319–5332, 2017.
19. H. Zhang, D.-K. Zhang, W.-X. Meng, and C. Li. “User pair-
ing algorithm with SIC in non-orthogonal multiple access
system,” in 2016 International Conference on Communi-
cations (ICC). IEEE, pp. 1–6.
20 . Y. Ch i , L. L i u , G . S o ng , C . Yu e n , Y. L . G u an , a n d Y. Li ,
“Practical MIMO-NOMA: low complexity and capacity-
approaching solution,” IEEE Trans. Wireless Commun.,
Vol. 17, no. 9, pp. 6251–6264, 2018.
21. L.Liu,Y.Chi,C.Yuen,Y.L.Guan,andY.Li,“Capacity-
achieving MIMO-NOMA: iterative LMMSE detection,”
IEEE Trans. Signal Process., Vol. 67, no. 7, pp. 1758–1773,
2019.
22. Y. Saito, Y. Kishiyama, A. Benjebbour, T. Nakamura,
A. Li, and K. Higuchi. “Non-orthogonal multiple access
(NOMA) for cellular future radio access,” in 2013 IEEE
77th vehicular technology conference (VTC Spring). IEEE,
2013, pp. 1–5.
D. SARKAR AND Y. BULO: DOWNLINK NOMA BASED TRANSMISSION PROTOCOL 15
23. B. Kimy, et al. “Non-orthogonal multiple access in a down-
link multiuser beamforming system,” in MILCOM 2013-
2013 IEEE Military Communications Conference. IEEE,
2013, pp. 1278–1283.
24. Z. Ding, F. Adachi, and H. Vincent Poor, “The application
of MIMO to non-orthogonal multiple access,” IEEE Trans.
Wireless Commun., Vol. 15, no. 1, pp. 537–552, 2015.
25. D. Tse, and P. Viswanath. Fundamentals of wireless commu-
nication.Berkeley:CambridgeUniversityPress,2005.
26. J.An,K.Yang,J.Wu,N.Ye,S.Guo,andZ.Liao,“Achieving
sustainable ultra-dense heterogeneous networks for 5G,”
IEEE Commun. Mag., Vol. 55, no. 12, pp. 84–90, 2017.
27. X.Gao,P.Wang,D.Niyato,K.Yang,andJ.An.“Anauction-
based time scheduling mechanism for backscatter-aided
RF-powered cognitive radio networks,” in 2018 IEEE Inter-
national Conference on Internet of Things (iThings) and
IEEE Green Computing and Communications (Green-
Com) and IEEE Cyber, Physical and Social Computing
(CPSCom) and IEEE Smart Data (SmartData). IEEE, 2018,
pp. 301–307.
28. Y. Kai, N. Yang, N. Ye, M. Jia, Z. Gao, and R. Fan,
“Non-orthogonal multiple access: achieving sustainable
future radio access,” IEEE Commun. Mag.,Vol.57,no.2,
pp. 116–121, 2018.
29. Y. Sun, D. W. K. Ng, Z. Ding, and R. Schober. “Optimal
joint power and subcarrier allocation for MC-NOMA sys-
tems,” in 2016 IEEE Global Communications Conference
(GLOBECOM). IEEE, 2016, pp. 1–6.
30. H. Tullberg, et al., “The METIS 5G system concept: meet-
ing the 5G requirements,” IEEE Commun. Mag., Vol. 54,
no. 12, pp. 132–139, 2016.
31. H. Wang, R. Song, and S.-H. Leung, “Throughput analysis
of interference alignment for a general centralized limited
feedback model,” IEEE Trans. Veh. Technol., Vol. 65, no. 10,
pp. 8775–8781, 2015.
32. Y.Sun,D.W.K.Ng,Z.Ding,andR.Schober,“Optimaljoint
power and subcarrier allocation for full-duplex multicar-
rier non-orthogonal multiple access systems,” IEEE Trans.
Commun., Vol. 65, no. 3, pp. 1077–1091, 2017.
33. F. Mokhtari, et al., “Download elastic trac rate optimiza-
tion via NOMA protocols,” IEEE Trans. Veh. Technol.,
Vol. 68, no. 1, pp. 713–727, 2018.
34. P. Xu, Z. Ding, X. Dai, and H. Vincent Poor. “NOMA:
an information theoretic perspective.” arXiv preprint
arXiv:1504.07751, 2015, pp. 1–6.
35. Z. Yang, Z. Ding, P. Fan, and N. Al-Dhahir, “A gen-
eral power allocation scheme to guarantee quality of
service in downlink and uplink NOMA systems,” IEEE
Trans. Wireless Commun., Vol. 15, no. 11, pp. 7244–7257,
2016.
36. Z. Ding, R. Schober, and H. Vincent Poor, “A general
MIMO framework for NOMA downlink and uplink trans-
mission based on signal alignment,” IEEE Trans. Wireless
Commun., Vol. 15, no. 6, pp. 4438–4454, 2016.
37. N. Zhang, J. Wang, G. Kang, and Y. Liu, “Uplink
nonorthogonal multiple access in 5G systems,” IEEE Com-
mun. Lett., Vol. 20, no. 3, pp. 458–461, 2016.
38. H. Tabassum, E. Hossain, and J. Hossain, “Modeling and
analysis of uplink non-orthogonal multiple access in large-
scale cellular networks using poisson cluster processes,”
IEEE Trans. Commun., Vol. 65, no. 8, pp. 3555–3570, 2017.
39.X.Yan,J.Ge,Y.Zhang,andL.Gou,“NOMA-based
multiple-antenna and multiple-relay networks over
Nakagami-m fading channels with imperfect CSI and SIC
error,” IET Commun., Vol. 12, no. 17, pp. 2087–2098, 2018.
40. Z. Shi, S. Ma, H. ElSawy, G. Yang, and M.-S. Alouini,
“Cooperative HARQ-assisted NOMA scheme in large-
scale D2D networks,” IEEE Trans. Commun., Vol. 66, no.
9, pp. 4286–4302, 2018.
41. Y. Bulo, Y. Saring, and C. T. Bhunia, “APC-PC combined
scheme in gilbert two state model: proposal and study,” J.
Inst. Eng., Vol. 98, no. 2, pp. 239–243, 2017.
42. T. Bhunia Chandan. “A few modied ARQ techniques,”
in Proceedings of the international conference on com-
munications, computers & devices, ICCCD-2000, vol. 2,
pp. 705–708.
43. A. Sastry, “Improving automatic repeat-request (ARQ) per-
formance on satellite channels under high error rate condi-
tions,” IEEE Trans. Commun., Vol. 23, no. 4, pp. 436–439,
1975.
44. T. BhuniaChandan, “ARQ review and modications,”
IETE Tech. Rev., Vol. 18, no. 5, pp. 381–401, 2001.
45. S. Lin, D. J. Costello, and M. J. Miller, “Automatic-repeat-
request error-control schemes,” IEEE Commun. Mag.,
Vol. 22, no. 12, pp. 5–17, 1984.
46. T. Bhunia Chandan, and A. Chowdhury. “Performance
analysis of ARQ techniques used in computer commu-
nication using delay as a parameter,” in Proceedings
of conference on computer networking and multimedia
(COMNAM-2000), Jadavpur University, Calcutta, India,
2000, pp. 22–24.
47. T. Bhunia Chandan, and A. Chowdhury. “ARQ technique
with variable number of copies in retransmission,” in Pro-
ceedings of conference on computer networking and mul-
timedia (COMNAM-2000), pp. 21–22.
48. T. Bhunia Chandan. “ARQ with two level coding with
generalized parity and i (i >1) copies of parts in retrans-
mission,” in Proceedings of National Conference on Data
Communications (NCDC-2000), Computer Society of
India, Chandigarh, India, vol. 19, 2000, pp. 7–8.
16 D. SARKAR AND Y. BULO: DOWNLINK NOMA BASED TRANSMISSION PROTOCOL
49. G. Caire, and D. Tuninetti, “The throughput of hybrid-
ARQ protocols for the Gaussian collision channel,” IEEE
Trans. Inf. T h eory, Vol. 47, no. 5, pp. 1971–1988, 2001.
50. Z. Yu, C. Zhai, and J. Liu, “Non-orthogonal multiple access
relaying with truncated ARQ,” IET Commun., Vol. 11, no.
4, pp. 514–521, 2017.
51.R.Kotaba,C.N.Manchon,N.M.K.Pratas,T.Baler-
cia, and P. Popovski. “Improving spectral eciency in
URLLC via NOMA-based retransmissions,” in ICC 2019-
2019 IEEE International Conference on Communications
(ICC), IEEE, 2019, pp. 1–7.
52. R. Chandran, and S. R. Pal. “A novel retransmission
scheme for HARQ enhancement in NOMA based LTE
systems,” in 2019 IEEE Wireless Communications and
Networking Conference (WCNC), 2019, pp. 1–5.
53. D. Cai, Z. Ding, P. Fan, and Z. Yang, “On the performance
of NOMA with hybrid ARQ,” IEEE Trans. Veh. Technol.,
Vol. 67, no. 10, pp. 10033–10038, 2018.
54. S. Joshi, and R. K. Mallik. “Cooperative NOMA with
AF relaying over Nakagami-m fading in a D2D net-
work,” in 2019 IEEE 89th Vehicular Technology Confer-
ence (VTC2019-Spring), 2019, pp. 1–6.
55. B. Joshi Sandeep, R. Manoj, and S. P. Dash. “Buer-
aided AF cooperative relaying network with NOMA trans-
mission scheme,” in 2020 IEEE International Conference
on Advanced Networks and Telecommunications Systems
(ANTS), 2020, pp. 1–6.
56.K.ChakrabortySwarnendu,R.S.Goswami,A.Bhunia,
andC.T.Bhunia,“Threenewinvestigationsofaggressive
packet combining to get high throughput,” Int. J. Comput.
Appl., Vol. 81, no. 5, pp. 41–44, 2013.
57. Y.Bulo,M.Anju,andC.T.Bhunia,“ARQtechniquewith
aggressive packet combining scheme for variable error rate
channels to reduce the bandwidth and power consump-
tion,” Int. J. Appl. Eng. Res., Vol. 11, no. 5, pp. 3181–3185,
2016.
AUTHORS
Debbarni Sarkar, her research interest
is on wireless communication, 5g tech-
nology, non-orthogonal multiple access,
hybrid automatic repeat request (HARQ)
protocols.
Corresponding author. Email: debbar-
nisarkar19@gmail.com
Ya k a B u l o ,isanassistantprofessor
at National Institute of Technology
Arunachal Pradesh in the department of
Electronics and Communication Engi-
neering. Her areas of interest are wireless
communication, wireless sensor network,
error control techniques, 5g technology,
non-orthogonal multiple access, hybrid
automatic repeat request (HARQ) protocols.
Email: yaka@nitap.ac.in
