Indonesian J our nal of Electrical Engineering and Computer Science V ol. 21, No. 2, February 2021, pp. 854 864 ISSN: 2502-4752, DOI: 10.11591/ijeecs.v21i2.pp854-864 r 854 V2X communication system with non-orthogonal multiple access: outage perf ormance perspecti v e T u-T rinh Thi Nguy en, Dinh-Thuan Do F aculty of Electronics T echnology , Industrial Uni v ersity of Ho Chi Minh City (IUH), Ho Chi Minh City , V ietnam Article Inf o Article history: Recei v ed Jun 9, 2020 Re vised Sep 11, 2020 Accepted Sep 25, 2020 K eyw ords: Non-orthogonal multiple access Outage probability V ehicle-to-e v erything ABSTRA CT T o achie v e lo w-latenc y and high-reliability (LLHR) for applications in the v ehicle- to-e v erything (V2X) netw orks, the non-orthogonal multipl e access (NOMA) is pro- posed for Long T erm Ev olution (L TE)as a promising technology . NOMA-V2X pro- vides higher spectrum ef ficienc y compared with the orthogonal multiple access (OMA) based V2X. The v ehicles are e xpected to serv e dif ferent services with v ariety of data transmission. The cluster of v ehicles could be grouped to achie v e better service from the transmitter sour ces. This study presents tw o-w ay relay assisted NOMA-V2X trans- mission by e xploiting amplify-and-forw ard (AF) and full-duple x technique. W e can benefits from potential applications of NOMA-V2X system with respec t to serving massi v e users and adapting higher bandwidth ef ficienc y . W e deri v e e xpressions of outage probability to e v aluate performance of tw o v ehic les and to impro v e the quality of service (QoS) for the de vice with the poor channel conditions. The main in v esti- g ation related tw o users’ performance which pro vides guidelines to design practical system. These e xpressions are further v erified by Monte-Carlo simulations. This is an open access article under the CC BY -SA license . Corresponding A uthor: Dinh-Thuan Do, F aculty of Electronics T echnology , Industrial Uni v ersity of Ho Chi Minh City (IUH), Ho Chi Minh City , V ietnam. Email: dodinhthuan@iuh.edu.vn 1. INTR ODUCTION As a candidate technique for forthcoming 5G netw orks, non-orthogonal multiple access (NOMA) net- w ork has recently dra wn in consi derable attentions [1]-[8]. In particular , the higher spectral ef ficienc y benefits can be achie v ed by the deplo yment of NOMA and it outperforms the traditional orthogonal multiple access (OMA) s cheme [1]-[3]. In practical NOMA systems, to achie v e lo w comple xity , the successi v e interference cancellation (SIC) decoding technique is needed to satisfy the performance of the NOMA system and it re- quires the user grouping as an important issue. In the recent w orks re g arding NOMA system, the impro v ed performance can be achie v ed as by emplo ying relaying netw orks [4]-[7], [9]-[13] with NOMA to introduce ne w paradigm termed as cooperati v e NOMA [8]. Re g arding system performa n c e, the optimal sum rate [14], [15], and the minimal transmit po wer [16] are introduced with respect to the user grouping. Recently , to pro vide smarter , safer and more ef ficient road traf fic, v ehicle-to-e v erything (V2X) com- munications ha v e a lot of achie v ements in both academia and industry [16]–[18]. Three kinds of V2X net- w orks including v ehicle-to-v ehicle (V2V), v ehicle-to-infrastructure (V2I) and v ehicle-to-pedestrian (V2P) are implemented to enable real-time traf fic information e xchange among infrastructure, v ehicles, and pedestrians [19]–[21]. In such a V2X, lo w access ef ficienc y and data congestion are caused by the f ast gro wth of number J ournal homepage: http://ijeecs.iaescor e .com Evaluation Warning : The document was created with Spire.PDF for Python.
Indonesian J Elec Eng & Comp Sci ISSN: 2502-4752 r 855 of connected v ehicles. The de v elopment of V2X communications need be tackled the challenges in v ehicular netw orks such as [22], [23]. This paper considers the ability of tw o pairs of v ehicle can be communicated via the Roadside Unit (RSU). 2. NETW ORK ARCHITECTURE AND PR O T OCOL DESCRIPTIONS 2.1. System ar chitectur e Figure 1 depicts a scenario of AF relay assisted tw o-w ay NOMA-V2X systems, all nodes are with single antenna e xcept for relay with tw o antennas for FD mode. The base stations (BSs) em plo y a RSU to serv e group of tw o v ehicles. In the multicasting scenario, RSU serv es multiple users using NOMA. In this case, v ehicles in the same group require to recei v e dif ferent information (e.g., v ehicle-specific control information) from the BS. The source S 1 ; S 2 are able to send the corresponding signals x 1 ; x 2 ( with po wer allocation f actors 1 ; 2 ) to the RSU in the same time. The constraint of po wer allocation f actors, i.e., 1 > 2 and 1 + 2 = 1 . It can be s hared by tw o source-destination Group1 = f S 1 ; U 1 g and Group2 = f S 2 ; U 2 g pairs. The transmit po wer at sources S 1 ; S 2 are the same, i.e. equals to P s . The channels for links S 1 -RSU, S 2 -RSU, RSU- U 1 and RSU- U 2 are h 1 ; h 2 ; g 1 ; g 2 . U 2 U 1 h 1 h 2 g 2 g 1 R S U S 2 S 1 Figure 1. System model of NOMA V2X 2.2. SINR calculation The recei v ed signal at RSU is gi v en by y RSU = p 1 P s h 1 x 1 + p 2 P s h 2 x 2 + P RSU f + RSU ; (1) where RSU is A WGN noise with v ariance of 2 0 . W e call f as s elf-channel due to FD mode applied at the RSU. The recei v ed signal at U i ; (i = 1 ; 2) can be e xpressed as follo ws: y U i = p P RSU g i p 1 P s h 1 x 1 + p 2 P s h 2 x 2 + p P RSU f + RSU + U i : (2) The amplify f actor is defined as follo ws: = 1 q 1 P s j h 1 j 2 + 2 P s j h 2 j 2 + P RSU j f j 2 + 2 0 ; (3) where s = P s 2 0 and RSU = P RSU 2 0 are transmission SNR of source and relay node, respecti v ely . V2X communication system with non-ortho gonal multiple access: outa g e ... (T u-T rinh Thi Nguyen) Evaluation Warning : The document was created with Spire.PDF for Python.
856 r ISSN: 2502-4752 The SINR at destination 1 in order to decode its o wn data can be written by U 1 = 1 s RSU j g 1 j 2 j h 1 j 2 2 s RSU j g 1 j 2 j h 2 j 2 + RSU j g 1 j 2 + 1 s j h 1 j 2 + RSU RSU j f j 2 j g 1 j 2 + 1 : (4) The recei v ed SINR for destination 2 to decode message x 1 is gi v en by U 2 ! 1 = 1 RSU s j g 2 j 2 j h 1 j 2 2 RSU s j h 2 j 2 j g 2 j 2 + RSU j g 2 j 2 + 1 s j h 1 j 2 + RSU RSU j f j 2 j g 2 j 2 + 1 : (5) Destination 2 detects its o wn message with the follo wing SINR. U 4 = 2 RSU s j h 2 j 2 j g 2 j 2 RSU j g 2 j 2 + 1 s j h 1 j 2 + RSU RSU j f j 2 j g 2 j 2 + 1 : (6) 3. OUT A GE AND THR OUGHPUT PERFORMANCE AN AL YSIS 3.1. The outage pr obability f or gr oup 1 The outage probability is basic metric sho wing probability to SINR less than threshold v alue. In particular , the outage probability of group 1 can be written as: OP FD 1 = Pr U 1 < 1 0 : (7) Ne xt, OP FD 1 can be computed as OP FD 1 = Pr   1 s RSU j g 1 j 2 j h 1 j 2 2 s RSU j g 1 j 2 j h 2 j 2 + RSU j g 1 j 2 + 1 s j h 1 j 2 + RSU RSU j f j 2 j g 1 j 2 + 1 < 1 0 ! = Pr 1 ; j g 1 j 2 1 0 RSU + Pr 0 @ j h 1 j 2 < RSU j g 1 j 2 2 s j h 2 j 2 + RSU j f j 2 + 1 + 1 1 s RSU 1 0 j g 1 j 2 1 ; j g 1 j 2 > 1 0 RSU 1 A =1 1 g 1 1 Z 1 0 RSU exp 0 @ RSU xX h 1 1 s RSU 1 0 x 1 x g 1 1 h 1 1 s RSU 1 0 x 1 1 A dx (8) Putting t = RSU 1 0 x 1 ) x = 1 0 RSU ( t + 1) then OP FD 1 has become OP FD 1 =1 1 0 RSU g 1 exp 1 0 g 1 RSU 1 0 X h 1 1 s 1 Z 0 exp 1 h 1 1 s + 1 0 X h 1 1 s 1 t 1 0 t g 1 RSU dt =1 exp 1 0 g 1 RSU 1 0 X h 1 1 s 2 s 1 0 g 1 RSU 1 h 1 1 s + 1 0 X h 1 1 s K 1   2 s 1 0 g 1 RSU 1 h 1 1 s + 1 0 X h 1 1 s ! (9) Indonesian J Elec Eng & Comp Sci, V ol. 21, No. 2, February 2021 : 854 864 Evaluation Warning : The document was created with Spire.PDF for Python.
Indonesian J Elec Eng & Comp Sci ISSN: 2502-4752 r 857 where X = 2 s j h 2 j 2 + RSU j f j 2 + 1 . Let Y = 2 s j h 2 j 2 + RSU j f j 2 ) X = Y + 1 then the outage probability of group 1 written ag ain as follo ws OP FD 1 ( Y ) =1 e 1 0 g 1 r 1 0 ( Y +1) h 1 1 s 2 s 1 0 g 1 RSU 1 h 1 1 s + 1 0 ( Y + 1) h 1 1 s K 1   2 s 1 0 g 1 RSU 1 h 1 1 s + 1 0 ( Y + 1) h 1 1 s ! =1 e 1 0 Y h 1 1 s 1 0 g 1 RSU 1 0 h 1 1 s 2 s 1 0 g 1 RSU 1 0 Y h 1 1 s + 1 h 1 1 s + 1 0 h 1 1 s K 1   2 s 1 0 g 1 RSU 1 0 Y h 1 1 s + 1 h 1 1 s + 1 0 h 1 1 s ! =1 2 e # 1 Y # 2 p # 3 Y + # 4 K 1 2 p # 3 Y + # 4 (10) where # 1 = 1 0 h 1 1 s , # 2 = 1 0 RSU g 1 + 1 0 1 s h 1 , # 3 = 1 0 1 0 1 s RSU g 1 h 1 , # 4 = 1 0 g 1 RSU 1 h 1 1 s + 1 0 h 1 # 1 s : OP FD 1 can be calculated as OP FD 1 = E Y n 1 2 e # 1 Y # 2 p # 3 Y + # 4 K 1 2 p # 3 Y + # 4 o = 1 Z 0 1 2 e # 1 Y # 2 p # 3 Y + # 4 K 1 2 p # 3 Y + # 4  f Y ( y ) dy =OP FD 1 1 + OP FD 1 ; 2 (11) W e ha v e F Y ( y ) = Y Z 0 f Y ( y ) dy = 1 f y RSU Z 0 e x f dx 1 f e y h 2 2 s y RSU Z 0 e 1 f r 1 h 2 2 s x dx: (12) Here we look at tw o cases for CDF and PDF: 3.1.1. Case 1 If 1 RSU f 1 h 2 2 s 6 = 0 , we ha v e F Y ( y ) = 1 RSU f RSU f 2 s h 2 e y RSU f 2 s h 2 2 s h 2 RSU f e y 2 s h 2 ; (13) f Y ( y ) = e y RSU f RSU f h 2 2 s + e y h 2 2 s h 2 2 s RSU f : (14) OP FD 1 1 can be computed as V2X communication system with non-ortho gonal multiple access: outa g e ... (T u-T rinh Thi Nguyen) Evaluation Warning : The document was created with Spire.PDF for Python.
858 r ISSN: 2502-4752 OP FD 1 1 = E Y n 1 2 e # 1 Y # 2 p # 3 Y + # 4 K 1 2 p # 3 Y + # 4 o =1 2 e # 2 RSU f h 2 2 s 1 2 e # 2 h 2 2 s RSU f 2 (15) where 1 = 1 R S U f + # 1 ; 1 = 1 Z 0 e 1 y p # 3 y + # 4 K 1 2 p # 3 y + # 4 dy = e 1 # 4 # 3   # 3 2 1 2 e # 3 1 1 ; # 3 1 1 2 M X m =0 ( 1 ) m # 4 m +1 # 3 m +1 G 2 ; 1 1 ; 3 # 4 j m 1 ; 0 ; m ! ; : (16) By using the lase equation in [25], v ol. 4, (3.16.2.4)], we ha v e: 2 = 1 Z 0 e 1 y p # 3 y K 1 2 p # 3 y dy = # 3 2 1 2 e # 3 1 1 ; # 3 1 : (17) and 3 = 1 # 3 # 4 R 0 e 1 # 3 y p y K 1 2 p y dy . Putting t = C y ! y = # 4 t ! dy = # 4 dt when y = 0 ! t = 0 , y = # 4 ! t = 1 ! C = 1 # 4 . Based on (18) we ha v e: 3 = # 4 # 3 1 Z 0 e 1 # 4 # 3 t p # 4 tK 1 2 p # 4 t dt = 1 2 M X m =0 ( 1 ) m # 4 m +1 # 3 m +1 G 2 ; 1 1 ; 3 # 4 j m 1 ; 0 ; m : (18) Where the lase equation follo ws the f act that e x = 1 P k =0 x k k ! in [24], (1.211.1)] and 1 R 0 x (1 x ) 1 K ( a p x ) dx = 2 1 a ( ) G 2 ; 1 1 ; 3 a 2 4 j 2 ; 0 ; 2 in [24], (6.952.2)]. And 2 = 1 Z 0 e 4 y p # 3 y + # 4 K 1 2 p # 3 y + # 4 dy = e 4 # 4 # 3   # 3 2 4 2 e # 3 4 1 ; # 3 4 1 2 M X m =0 ( 4 ) m # 4 m +1 # 3 m +1 G 2 ; 1 1 ; 3 # 4 j m 1 ; 0 ; m ! : (19) Indonesian J Elec Eng & Comp Sci, V ol. 21, No. 2, February 2021 : 854 864 Evaluation Warning : The document was created with Spire.PDF for Python.
Indonesian J Elec Eng & Comp Sci ISSN: 2502-4752 r 859 where 4 = 1 h 2 2 s + # 1 . By using the equation x /2 K ( a p x ) = ( +1) (2 p ) +1 e a 2 4 p ; a 2 4 p in [25], v ol. 4, eq. (3.16.2.4)], we can computed 5 : 5 = 1 Z 0 e 4 y p # 3 y K 1 2 p # 3 y dy = # 3 2 4 2 e # 3 4 1 ; # 3 4 ; (20) 6 = 1 # 3 # 4 Z 0 e 4 # 3 y p y K 1 (2 p y ) dy = 1 2 M X m =0 ( 4 ) m # 4 m +1 # 3 m +1 G 2 ; 1 1 ; 3 4 # 4 4 j m 1 ; 0 ; m : (21) 3.1.2. Case 2: If 1 RSU f 1 h 2 2 s = 0 , we ha v e F Y ( y ) = 1 e y RSU f y RSU f e y h 2 2 s ; (22) f Y ( y ) = y Y Y e y Y : (23) OP FD 1 ; 2 is gi v en as OP FD 1 ; 2 = E Y n 1 2 e # 1 Y # 2 p # 3 Y + # 4 K 1 2 p # 3 Y + # 4 o =1 2 Y Y 1 Z 0 e 1 Y # 1 y # 2 1 # 3 ( y # 3 + # 4 ) # 4 # 3 p # 3 y + # 4 K 1 2 p # 3 y + # 4 dy =1 4 + 5 : (24) where 4 = 7 1 Z 0 e 8 y ( # 3 y + # 4 ) 3/2 K 1 2 p # 3 y + # 4 dy = 7 e 8 # 4 # 3 ( 1 2 ) = 7 e 8 # 4 # 3 " # 3 8 2 W 2 ; 1/2 # 3 8 1 2 M X m =0 ( 8 ) m # 4 m +2 # 3 m +1 G 2 ; 1 1 ; 3 # 4 j m 1 ; 0 ; m # (25) By using the equation 1 R 0 x /2 K ( a p x ) dx = p 1/2 a + 2 + 1 2 + 1 exp a 2 8 p W 1/2 ; /2 a 2 4 p in [25], v ol. 4, eq. (3.16.2.3)] and 1 R 0 x /2 K ( a p x ) dx = ( +1) (2 p ) +1 exp a 2 4 p ; a 2 4 p in [25], v ol. 4, eq. (3.16.2.4)], we can computed 1 , 2 : 1 = 1 Z 0 e 8 y # 3 3/2 y 3/2 K 1 2 p # 3 y dy = # 3 8 2 W 2 ; 1/2 # 3 8 ; (26) V2X communication system with non-ortho gonal multiple access: outa g e ... (T u-T rinh Thi Nguyen) Evaluation Warning : The document was created with Spire.PDF for Python.
860 r ISSN: 2502-4752 2 = 1 # 3 # 4 Z 0 e 8 # 3 y y 3/2 K 1 (2 p y ) dy = 1 2 M X m =0 ( 8 ) m # 4 m +2 # 3 m +1 G 2 ; 1 1 ; 3 # 4 j m 1 ; 0 ; m ; (27) and 5 = 7 # 4 1 Z 0 e 8 y p # 3 y + # 4 K 1 2 p # 3 y + # 4 dy = e 8 # 4 # 3   7 # 4 # 3 2 8 2 e # 3 8 1 ; # 3 8 7 2 M X m =0 ( 8 ) m # 4 m +2 # 3 m +1 G 2 ; 1 1 ; 3 # 4 j m 1 ; 0 ; m ! (28) where 7 = 2 e # 2 Y Y # 3 ; 8 = 1 Y + # 1 ; 9 = # 3 2 8 2 e # 3 8 1 ; # 3 8 ; 10 = 1 2 M P m =0 ( 8 ) m # 4 m +1 # 3 m +1 G 2 ; 1 1 ; 3 4 # 4 4 j m 1 ; 0 ; m : 3.2. The outage pr obability f or gr oup 2 The e xact outage probability of group 2 can be written as OP FD 2 =1 Pr U 2   1 1 0 ; U 2 2 0 (29) The outage probability in (29) can be computed as OP FD 2 =1 Pr 0 @ 1 RSU s j g 2 j 2 j h 1 j 2 2 RSU s j h 2 j 2 j g 2 j 2 + RSU j g 2 j 2 + 1 s j h 1 j 2 + RSU RSU j f j 2 j g 2 j 2 +1 1 0 ; 2 RSU s j h 2 j 2 j g 2 j 2 RSU j g 2 j 2 + 1 s j h 1 j 2 + RSU RSU j f j 2 j g 2 j 2 +1 2 0 1 A =1 OP FD 2 ; 1 + OP FD 2 ; 2 : (30) 3.2.1. Case 1: If max = 1 1 s 1 0 j h 1 j 2 2 s j h 2 j 2 1 RSU j f j 2 , we ha v e: OP FD 2 ; 1 = 1 Z 0 f j f j 2 ( z ) dz 1 Z 2 0 2 s ( RSU z +1) f j h 2 j 2 ( y ) dy 1 0 2 1 1 2 0 +1 y Z 1 0 1 s ( 2 s y + RSU z +1)   1 F j g 2 j 2   1 RSU 1 s x + 1 1 s 1 0 x 2 s y RSU z 1 !! f j h 1 j 2 ( x ) dx | {z } = 4 ; (31) Indonesian J Elec Eng & Comp Sci, V ol. 21, No. 2, February 2021 : 854 864 Evaluation Warning : The document was created with Spire.PDF for Python.
Indonesian J Elec Eng & Comp Sci ISSN: 2502-4752 r 861 Continuing the calculation process, we ha v e OP FD 2 ; 1 = 1 Z 0 f j f j 2 ( z ) dz 2 6 6 6 6 6 6 6 6 6 4 1 h 2 1 Z 2 0 2 s ( RSU z +1) e 1 0 RSU g 2 e 1 0 2 1 h 1 1 2 0 +1 + 1 h 2 y dy | {z } = # 1 1 h 2 1 Z 2 0 2 s ( RSU z +1) e 1 0 RSU g 2 e 2 1 0 1 h 1 + 1 h 2 y e RSU 1 0 1 s h 1 z e 1 0 1 s h 1 dy | {z } = # 2 3 7 7 7 7 7 7 7 7 7 5 = e 1 0 2 0 1 s h 1 1 2 0 +1 2 0 2 s h 2 1 0 RSU g 2 h 2 1 0 2 1 h 1 1 2 0 + 1 + 1 h 2 1 Z 0 e 1 0 2 1 h 1 1 2 0 +1 + 1 h 2 RSU 2 0 2 s z f j f j 2 ( z ) dz | {z } = # 3 e 1 0 r g 2 1 0 1 s h 1 2 1 0 1 h 1 + 1 h 2 2 0 2 s h 2 2 1 0  h 1 + 1 h 2 1 Z 0 e RSU 1 0 1 s h 1 + RSU 2 0 2 s 2 1 0 1 h 1 + 1 h 2  z f j f j 2 ( z ) dz | {z } = # 4 = e 1 0 2 0 1 s h 1 1 2 0 +1 2 0 2 s h 2 1 0 RSU g 2 h 2 f 1 0 2 1 h 1 1 2 0 + 1 + 1 h 2 h 1 0 2 1 h 1 1 2 0 + 1 + 1 h 2 RSU 2 0 2 s + 1 f i e 1 0 RSU g 2 1 0 1 s h 1 2 1 0 1 h 1 + 1 h 2 2 0 2 s h 2 f 2 1 0 1 h 1 + 1 h 2 h RSU 1 0 1 s h 1 + r 2 0 2 s 2 1 0 1 h 1 + 1 h 2  + 1 f i : (32) where 4 = 1 h 1 e 1 0 RSU g 2 1 0 2 1 1 2 0 +1 y R 1 0 1 s ( 2 s y + RSU z +1) e x h 1 dx , # 1 = e 1 0 2 0 1 s h 1   1 2 0 +1 ! 2 0 2 s h 2 1 0 RSU g 2 e   1 0 2 1 h 1   1 2 0 +1 ! + 1 h 2 ! RSU 2 0 2 s z 1 0 2 h 2 1 h 1 1 2 0 +1 +1 , # 2 = e 1 0 RSU g 2 1 0 1 s h 1   2 1 0 1 h 1 + 1 h 2 ! 2 0 2 s e   RSU 1 0 1 s h 1 + RSU 2 0 2 s   2 1 0 1 h 1 + 1 h 2 !! z h 2 2 1 0 1 h 1 + 1 h 2 , # 3 = e 1 0 2 0 1 s h 1   1 2 0 +1 ! 2 0 2 s h 2 1 0 RSU g 2 h 2 f 1 0 2 1 h 1 1 2 0 +1 + 1 h 2  1 0 2 1 h 1 1 2 0 +1 + 1 h 2 RSU 2 0 2 s + 1 f , # 4 = e 1 0 RSU g 2 1 0 1 s h 1   2 1 0 1 h 1 + 1 h 2 ! 2 0 2 s h 2 f 2 1 0 1 h 1 + 1 h 2  RSU 1 0 1 s h 1 + RSU 2 0 2 s 2 1 0 1 h 1 + 1 h 2  + 1 f . V2X communication system with non-ortho gonal multiple access: outa g e ... (T u-T rinh Thi Nguyen) Evaluation Warning : The document was created with Spire.PDF for Python.
862 r ISSN: 2502-4752 3.2.2. Case 2: If max = 1 2 s 2 0 j h 2 j 2 1 RSU j f j 2 , we ha v e: OP FD 2 ; 2 = 1 Z 0 f j f j 2 ( z ) dz 1 Z 2 0 2 s ( RSU z +1) f j h 2 j 2 ( y ) dy 1 Z 1 0 2 1 1 2 0 +1 y   1 F j g 2 j 2   1 RSU 1 s x + 1 2 s 2 0 y RSU z 1 !! f j h 1 j 2 ( x ) dx | {z } = 3 = 2 2 0 2 s RSU f 1 X k =1 k k g 2 ( 1 s h 1 ) k 1 e 4 2 0 2 s h 2 s 2 (1 + E ) 1 g 2 k +1 RSU 2 5 1 g 2 k +1 1 Z 0 e 1 f + 1 RSU RSU 2 + RSU 2 0 2 s h 2 z z k +1 K k +1   2 s 1 (1 + RSU 5 z + 5 ) 2 g 2 ! dz : (33) where 1 = 1 0 2 h 1 1 1 2 0 + 1 ; 2 = 2 s RSU 2 0 , 4 = s h 1 1 1 g 2 2 + 1 RSU 2 , 5 = s RSU h 1 1 1 2 : 3.3. Thr oughput The throughput in delay-limited transmission mode is gi v en by 1 = 1 OP FD 1 R 1 ; 2 = 1 OP FD 2 R 2 : (34) 4. RESUL T AND DISCUSSION Figures 2 and 3 demonstrate outage probability of tw o v ehicles. It can be observ ed that outage prob- ability impro v es significantly at high SNR. There is e xistence performance g ap among tw o v ehicles due to dif ferent po wer allocation f actors. It is further confirmed that outage probability cannot impro v e at v ery high SNR re g ardless of changing tar get rates R 1 ; R 2 . In these simulations, Monte-Carlo and analytical simulations are matched tightly and it confirmed our deri v at ions are correct. Figure 4 e xamines impact of interference chan- nel related to FD mode on outage probability . When changing f from 0 (dB) to 30 (dB) outage probability becomes w orse significantly . Figure 5 sho ws throughput v ersus transmit SNR . Increasing from -20 (dB) to 15 (dB), throughput increases significantly , b ut it meets the ceiling at high SNR re gion. -10 -5 0 5 10 15 20 25 30 35 40 10 -2 10 -1 10 0 Figure 2. Outage probability: R 1 = 0 : 5 bps/Hz, R 2 = 1 bps/Hz. -10 -5 0 5 10 15 20 25 30 35 40 10 -3 10 -2 10 -1 10 0 Figure 3. Outage probability: 1 = 0 : 9 , 2 = 0 : 1 . Indonesian J Elec Eng & Comp Sci, V ol. 21, No. 2, February 2021 : 854 864 Evaluation Warning : The document was created with Spire.PDF for Python.
Indonesian J Elec Eng & Comp Sci ISSN: 2502-4752 r 863 -20 -15 -10 -5 0 5 10 15 20 25 30 10 -3 10 -2 10 -1 10 0 Figure 4. Outage probability: R 1 = 0 : 1 bps/Hz, R 2 = 0 : 1 , 1 = 0 : 9 , 2 = 0 : 1 . -20 -15 -10 -5 0 5 10 15 20 25 30 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 Figure 5. Throughput: 1 = 0 : 9 , 2 = 0 : 1 . 5. CONCLUSION In this paper , tw o pairs of users in NOMA-V2X systems ha v e been proposed for 5G cellular V2X communications. The fix ed po wer allocation f actors are applied to hi ghlight dif ferent outage performance of each group of user . W e pro vided e xact e xpressions of outage probability to e v aluate system performance. W e sho w that the formulated e xpression is v erified via simulations. F ortunately , it indicates reasonable performance of tw o v ehicles in NOMA-V2X if self-interference channel is controlled well. Simulation results demonstrate that the proposed scheme e xhibits better performance at high SNR at sources. REFERENCES [1] Z. Ding, et al., ”A Surv e y on Non-Orthogonal Multiple Access for 5G Netw orks: Research Challenges and Future T rends, IEEE J. Sel. Areas Commun. , v ol. 35, no. 10, pp. 2181-2195, Oct. 2017. [2] T .-L. Nguyen and Dinh-Thuan Do, ”Exploiting Impacts of Intercell Interference on SWIPT -assisted Non- orthogonal Multiple Access, W ireless Communications and Mobile Computing , 2018. [3] F . Liu, et al., ”Proportional f airness-based user pairing and po wer all ocation for non-orthogonal multiple access, Proc. IEEE PIMRC. , pp. 1127-1131, 2015. [4] X.-X. Nguyen and Dinh-Thuan Do, ”Maximum Harv ested Ener gy Polic y in Full-Duple x Relaying Net- w orks with SWIPT , in International Journal of Communication Systems (W ile y) , v ol. 30, no. 17, pp. 2181-2195, Jul. 2017. [5] Dinh-Thuan Do, et al., ”W ireless po wered relaying netw orks under imperfect channel state information: system performance and optimal polic y for i nstantaneous rate, Radioengineering, v ol. 26, no. 3, pp. 869-877, Sep. 2017. [6] X.-X. Nguyen and Dinh-Thuan Do, ”Optimal po wer allocation and throughput performance of full-duple x DF relaying netw orks with wireless po wer transfer -a w are channel, EURASIP Journal on W ireless Com- munications and Netw orking, Sep. 2017. [7] T .-L. Nguyen; Dinh-Thuan Do, ”A ne w look at AF tw o-w ay relaying netw orks : ener gy harv esting ar - chitecture and impact of co-channel interference, Annals of T elecommunications, v ol. 72, no. 11, pp. 669-678, Dec. 2017. [8] Dinh-Thuan Do and C.-B. Le, ”Application of NOMA in W ireless System with W ireless Po wer T ransfer Scheme: Outage and Er godic Capacity Performance Analysis, in Sensors , v ol. 18, no. 10, pp. 669-678, Oct. 2018. [9] M. F . Kader , et al., ”Full-Duple x Non-Orthogonal Multiple Access in Cooperati v e Relay Sharing for 5G Systems, IEEE T ransactions on V ehicular T echnology , v ol. 67, no. 7, pp. 5831-5840, July 2018, doi: 10.1109/TVT .2018.2799939. [10] Dinh-Thuan Do, C.-B. Le, ”Exploiting Outage Performance of W ireless Po wered NOMA, TELK OM- NIKA T elecommunication, Computing, Electronics and Control , v ol. 16, no. 5, pp. 1907-1917, 2018. V2X communication system with non-ortho gonal multiple access: outa g e ... (T u-T rinh Thi Nguyen) Evaluation Warning : The document was created with Spire.PDF for Python.