Multi-Points Cooperative Relay in NOMA System with N-1 DF Relaying Nodes in HD/FD mode for N User Equipments with Energy Harvesting

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1 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 Artcle Mult-Ponts Cooperatve Relay n OMA System wth -1 DF Relayng odes n HD/FD mode for User Equpments wth Energy Harvestng Thanh-am Tran 1,,, Mroslav Voznak, 1 Emal: thanh.nam.tran.st@vsb.cz Emal: mroslav.voznak@vsb.cz Faculty of Electrcal Engneerng Computer Scence, Techncal Unversty of Ostrava, 17. lstopadu 17/15, Ostrava-Poruba, Czech Republc; Faculty of Electroncs Telecommuncatons, Sa Gon Unversty, Tran Bnh Trong st., Dct. 5, Hochmnh cty, Vetnam. Abstract: on-orthogonal Multple Access OMA s the key technology promsed to be appled n next-generaton networks n the near future. In ths study, we propose a mult-ponts cooperatve relayng MPCR OMA model nstead of ust usng a relay as the prevous studes. Based on the channel state nformaton CSI, the base staton BS selects a closest user equpment UE sends a superposed sgnal to ths UE as a frst relay node. We have assumed that there are UEs n the network th UE, whch s farthest from BS, has the poorest qualty sgnal transmtted from the BS compared other UEs. th UE receved the forwarded sgnal from -1 relayng nodes that are UEs wth better sgnal qualty. At the th relayng node, t detect ts own symbol by usng successve nterference cancellaton SIC wll forward the composte sgnal to the next closest user, namely +1th UE, nclude an excess power whch wll use for energy harvestng EH ntenton at the next UE. By these, the farthest UE n network can be sgnfcantly mproved. In addton, closed-form expressons of outage probablty for users over both the Raylegh akagam-m fadng channels are also presented. Analyss smulaton results performed by Matlab software whch are presented accurately clearly show that the effectveness of our proposed model ths model consstents wth the mult-access wreless network n future. Keywords: Cooperatve OMA; mult-ponts DF relayng nodes; half-duplex; full-duplex; Raylegh fadng channels; akagam-m fadng channels; energy harvestng 1. Introducton The next-generaton network 5G technology has the advantage of ncreasng system capacty by superor sharng-spectrum effcency [1]. Therefore, multple users n the network can be served n the same frequency b/tme slot varous allocaton power coeffcents by the key technology s called on-orthogonal Multple Access OMA. The s fundamentally dfferent from prevous orthogonal access methods, e.g., Orthogonal Multple Access OMA []. In OMA system, the users wth better channels condtons are allocated less transmttng power coeffcents. On another h, the users wth worse channels condtons are allocated more transmttng power coeffcents to guarantee the qualty of servce for all users n the system. After recevng a superposed sgnal, successve nterference cancellaton SIC s done at the end users. In [3], the authors nvestgated the mpact of mperfect SIC on the analyss performance of OA system. Ther analyss results showed that even SIC s not perfect, the performance of the OMA system s stll better than the orthogonal system. A down-lnk OMA wreless network was studed n [4] by consderng to use a relay for forwardng sgnals to combat the fadng effect of the transmsson channel. Authors appled to dual-hop relayng systems wth decode--forward DF or amplfy--forward AF protocols [5]. Relay full-duplex FD model over the Raylegh fadng channels usng the DF protocol was 18 by the authors. Dstrbuted under a Creatve Commons CC BY lcense.

2 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 of 1 nvestgated the performance by optmzng the transmt power factor [6]. The study mpacts of relay selecton of cooperatve OMA on the performance system [7]. the authors n [8] proposed a novel best cooperatve mechansm BCM for wreless energy harvestng spectrum sharng n 5G network. The [9]-[11] nclude amplfy--forward AF decode--forward DF relayng. In [11], t showed that a dual-hop power lne communcaton PLC system can mprove the system capacty compared to drect-lnk DL transmsson. And M. Rabe et. al. [1] proposed usng Mult-hop relay nstead of use one hop relay or dual-hop relays. Ths study, the authors nvestgated the energy effcency over PLC channels wth assumng log-normal fadng. The studes [13] [14] analyzed the system performance of mult-hop AF/DF relayng over PLC channels n terms of average bt error ergodc capacty. These studes showed that the system performance can be mprove by ncreasng the number of relayng. In addton, The authors n [15] studed the mpact of relay selecton RS on system performance. The compared results on two-stage versus max-mn RS showed that cooperatve OMA system over Raylegh fadng channels wth two-stage RS s better than max-mn one. We hypotheszed that there are users wth the th user at the far end from BS wth the worst channel condton. The QoS of the th user can be mproved wth the -1 user s cooperaton nstead of ust recevng a relay cooperaton. At each node perform the best neghbor selecton to forward the sgnal next neghbor. The best selecton of neghbors s repeated untl the sgnal reaches the destnaton In addton, we also consder energy harvestng at UEs. The exploson of the number of wreless devces, rado frequency RF energy harvestng becomes a potental technology to convert the energy of recevng wreless sgnal nto electrcty. Therefore, the MPCR s not only transmttng nformaton but also delverng energy to the users. In Ref. [16]-[18], there are only users located close BS can collect energy. Because sgnal recepton energy collecton can not be done smultaneously. Thus, the users need to dvde the receved sgnal for EH nformaton decodng ID by usng power splttng PS or tme swtchng TS whch was called "receved TS" [19] []. Though the PS approach has been shown to mostly outperform the receve-ts approach, however, the PS s complcated neffcent for practcal mplementaton. The research results have shown that PS s better than TS, however, PS s more complex dffcult to practcal applcaton than TS. In our study, we consder on compressng both nformaton energy n one transmsson phase nstead of splttng t nto two transmsson phases as the prevous studes. And a user faraway from BS can stll receve nformaton collect energy from the nearest relay node. See our model n Fg. 1 for more detal. In ths study we focus on MPCR n OMA network to mprove the qualty of servce QoS for the user faraway form BS wth poor sgnal. In terms of contrbutons n our research, our man contrbutons nclude: The frst, we propose a down-lnk sde OMA network wth rom UEs. The next, we propose a method to mprove QoS for farthest dstance th UE from BS by usng 1 UEs as DF relayng nodes n HD or FD modes. UE relayng node receves forwards a superposed sgnal to next hop whch s nearest from UE, namely UE +1. Ths work wll loop untl the superposed sgnal s sent to last UE, namely UE. A algorthm for selectng relay nodes n MPCR s also presented clearly n next secton. At UE wth > 1, the receved sgnal has an excess power s used for energy harvestng to charge the battery wth assumng unlmted capacty of the battery. In addtonal, we nvestgate fnd an outage probablty system throughput for each UE, whch are wrtten n closed-form expressons. Further, The analyss smulaton results are presented n a clear way by the Monte Carlo smulaton 1 6 samples of channels from the Matlab software to prove our propostons. Ths artcle s presented as follows. In next secton, namely Expermental Models, we propose models analyss two transmsson scenaros whch are called 1 relayng nodes n HD or FD modes. In thrd secton, we have analyzed the system s performance on outage probablty system throughput. In secton number IV, we use Matlab software to smulate results wll be

3 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 3 of 1 also presented n ths secton. A summary of the results of our study would be presented n secton V, namely Concluson. End of ntroducng secton. otce: In our study, we use a few notatons ncluded as h a,b s a channel from source a to destnaton b. α s an allocaton power coeffcent for th UE. y Ω s the receved sgnal at th UE wth Ω protocol. γ x Ω s a sgnal-to-nterference-plus-nose-ratos SIRs at th UE whle th UE decodes x symbol. Pr {.} s a probablty. Θ Ω s a outage probablty of th UE wth Ω protocol over R or ℵ whch s Raylegh or akagam-m fadng channels, respectvely. R s a bt rate threshold of th UE.. Expermental Models In prevous studes about OMA, a drect down-lnk scenaro s consdered to serve a number of users n the same tme slot. However, n such studes, they are usually fxed number of users. Therefore, they have not shown the generalty of the model. In order to ensure the generalty, we have upgraded the model to a rom unpredctable number of users..1. Drect lnk scenaro Based on proposed model n Fg. 1, the BS send a superposed sgnal to all UEs n the same tme slot as expressed S = P =1 α x, 1 Thus, the receved sgnal at all UEs would be expressed as y Dr = h, P =1 α x + n, where h,, wth = {1, }, s denoted as the fadng channels from BS to each UE over Raylegh fadng or akagam-m fadng. And, s the rom number of UEs oned to network, α n rule wth α = 1 s allocaton power coeffcent for each UE P s the transmsson power of BS. n s =1 denoted the addtve whte Gaussan nose AWG of th UE, = {1, }, where n C, wth zero mean varance. It s mportant to notce that the channel coeffcent from BS to each UE, n pared, s expressed as h, n our expressons. In our model, the frst user n the nearest dstance from the BS wth the strongest sgnal qualty was ordered frst n the channel gan lst. And the lst s n decreasng order as follows h,1 > h, >... > h, >... > h, 1 > h, 3 Accordng to the OMA theory, users wth the worst sgnal qualty should be gven prorty to allocate the hghest transmttng power factor. Another assumpton that does not affect the OMA characterstcs, we have assumed that the BS already owns the channel state nformaton CSI of all UEs fully. Therefore, the lst of allocaton power factors s arranged n descendng order for each UE n the network as α 1 < α <... < α <... < α 1 < α. 4

4 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 4 of 1 Sgnals are sent to users from BS n the same power doman wth hopng of mprovng servce qualty farness among users on a near-by-far rule. In Fg. 1, because the x symbol has the strongest allocaton power factor. Therefore, x symbol wll be frst decoded at all UEs n the network by applyng successve nterference cancellaton SIC []. And the order of decodng s done sequentally accordng to the reversed lst of power factor allocatons presented n 4 expresson. The Sgnal-to-nterference-plus-nose ratos SIRs of all UEs have been expressed as γ Dr x = h, ρ α h, 1 ρ α k +1, 5 k=1 where = {, } = {, }. In a specal case at 1st UE, after t decoded x symbols wth = {, } by usng 5, UE 1 decodes ts own symbol x 1 wth only self-nterference n 1 as γ Dr 1 x 1 = h,1 ρ α 1. 6 And ρ n 5 or 6 s sgnal-to-nose rato SR whch can be calculated by ρ = P, 7 where = {, 1}, e.g., ρ = P / wth P s the transmttng power of BS. The nstantaneous bt rate of each UE s showed by where = {1, } = {, }... 1 DF relayng nodes scenaro R x Dr = 1 log 1 + γ x Dr, 8 On another h, system model n [1] has only one relayng to mprove the QoS of UEs whch are faraway from the BS. We propose a mproved model wth usng a MPCR model nstead of usng only one user as a relay devce. See on Fg. 1, there are users n the network wth descendng order channel condtons wth th UE has the poorest sgnal compared to the other UEs h,1 h 1, h -1, h -1, h,1 h 1, h -1, h -1, S UE UE UE 1 UE S UE UE UE 1 UE a DF relayng nodes n HD mode. b DF relayng nodes n FD mode. Fgure 1. The OMA system wth 1 relayng nodes n HD/FD modes. The authors n [15] proposed the relay selecton method to choce the best relay wth the best channel condton by usng two-stage relay selecton protocol whch outperforms versus max-mn relay selecton protocol. There s a dfference compared model n [15] versus our model. The author n [15] selected a best relay n relays to serve for two other users. In our proposed model Fg. 1, all of 1

5 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 5 of 1 UEs can be selected for relayng node. A selected relay nodes set s ntalzed empty ϖ =, a frst relayng node can be selected by { } ϖ 1 = max R x Ω 1 > R1, 9 where R x1 s gven by, ϖ 1 has been added nto ϖ = ϖ ϖ 1 then. BS sends a superposed sgnal to the closest dstance user wth strongest channel condton, namely UE 1 n the Fg. 1a 1b, after BS selected UE 1 as a relay successfully. It s mportant to pont out the dfference. In ths study, at each relay node has a sngle or a twn antenna woks n HD or FD mode. The receved sgnals at UE 1 n HD or FD modes are respectvely the same lke or 1 as y FD 1 = h,1 P =1 α x + h LI,1 P x 1 + n 1, 1 where h LI,1 s the nterference channel generated by the tself transmtter antenna, n 1 s the ntrnsc nose of the devce UE 1. In case of the UE 1 s workng n HD relayng mode, UE 1 decodes ts own symbol by applyng 5 6, respectvely. On another h, the UE 1 s workng n FD relayng mode, UE 1 decodes x symbol wth = {, } or = 1 by applyng SIRs n 11a or 11b, respectvely, γ1 x FD h,1 ρ α = h,1 1 ρ α UEk + h LI,1 ρ k=1 11a = h,1 ρ α 1 h LI,1 ρ b Then, UE 1 sends a mxed sgnal, namely S 1 n 13, to next UE whch s next nearest relay node, namely UE. The second relay node can be selected by applyng 9 as } ϖ = max {R Ω x > R, = {1, }, ϖ, 1 where R Ω s also gven by not beng contaned n ϖ whch s a selected relay nodes set. We removed UE wth ϖ from the relay selecton because the sgnal could be sent back to the prevous relay node the superposed sgnal s unable send to UE. And, the ϖ s also added nto ϖ then. ote that the nearest neghbor represented n [5] [6] are neghbors closest to the BS. However, the authors n [] have extended the defnton of nearest neghbor as the devce can set up the transmsson channel n the best condton compared to other devces. A mxed sgnal s sent to the next relay node as expressed S 1 = P 1 α1 x + = α x, 13 where x s a empty symbol whch was also namely x 1 decoded at UE 1. The receved sgnals at UE n both HD FD relayng modes are expressed as, respectvely, y HD = h 1, P1 α1 x + = α x + n, 14

6 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 6 of 1 y FD =h 1, P1 α1 x + = α x + h LI, P x + n, 15 where h 1, s the channel from UE 1 to UE, P 1 s denoted as transmttng power at UE 1, h LI, s loop nterference channel from transmttng antenna to recevng one at UE. Specally, the x 1 symbol exsted n 1 but t was replaced by x n Because x 1 was prevously decoded removed from the mxed sgnal by U 1. Therefore, the power porton α 1 of the x symbol does not contan nformaton becomes redundant n the mxed sgnal. We wll use ths excess power for energy harvestng purposes as descrbng n the next secton The SIRs for decodng x symbol = {, 3} ts own symbol, namely x wth =, at UE n both HD FD relayng modes can be expressed as, respectvely, γ x HD h 1, ρ 1 α = 16a h 1, 1 ρ 1 α k + 1 k= = h 1, ρ 1 α, 16b γ FD x = h 1, ρ 1 α h 1, 1 ρ 1 α k + h LI, ρ + 1 k= 17a = h 1, ρ 1 α h LI, ρ + 1, 17b where 16a 17a wth = {, 3}. Or 16b 17b wth =. After UE decoded ts own symbol, t selects a next relay node sends a new superposed sgnal to next nearest UE, namely UE 3. Ths work wll loop untl a superposed sgnal sent to farthest UE, namely UE n Fg. 1. Proposed 1: In our study, we propose a energy harvestng model to use excess power n the mxed sgnals for purposng energy harvestng as Fg.. As expressng n 18 19, the receved sgnals at th UE, where = {, }, have an empty x symbol wth no nformaton. Thus, the transmt power coeffcents of each empty symbol can be harvested. In prevous studes, the power for energy harvestng was transmtted to users on dfferent tme slots or on dfferent antennas on the recevers. But n ths study, we use only one antenna for recevng both sgnals energy from the transmtter. In generally, the receved sgnals at UE n both HD FD relayng nodes can be rewrtten by, respectvely y HD = h 1, P 1 y FD =h 1, P 1 1 αl x + k= 1 αl x + αk x k k= αk x k + n, 18 + h LI, P x + n, 19

7 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 7 of 1 h -1, h LI, h,+1 UE th x symbol +1th x symbol thx symbol Decode α k va k={1,-1} Energy Harvestng Mx Forward Fgure. DF protocol EH protocol at th UE node. where y HD y FD are denoted as recevng sgnals at UE node, h 1, s the channels from prevous node to current node, P 1 P are transmttng power of prevous UE current UE, respectvely. It s mportant to notce that 1 α l + α k = 1. k= The SIRs of each th UE relayng node for detectng x symbol n HD FD modes are expressed as, respectvely γ x HD h 1, ρ 1 α =, a h 1, 1 ρ 1 α k + 1 k= = h 1, ρ 1 α = h,1 ρ α 1, b γ x FD h 1, ρ 1 α =, 1a h 1, 1 ρ 1 α k + h LI, ρ + 1 k= = h 1, ρ 1 α h LI, ρ + 1 = h,1 ρ α 1 h LI,1 ρ 1 + 1, 1b where a, 1a wth = {, } = {, }. And b 1b wth = = 1. In OMA theory, reachable nstantaneous bt rate can be calculated by R Ω x = 1 log where Ω = {HD, FD}, = {1, } = {, }. A selected relay node can be performed by 1 + γ Ω x, } ϖ = max {R Ω x > R, = {1, }, ϖ. 3 And, a selected relay node set ϖ after the sgnal has been sent to the UE ncluded ϖ = ϖ 1 ϖ... ϖ 1 4

8 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 8 of 1 3. The System Performance Analyss In ths secton, we evaluate the performance of the system that we have proposed based on outage probablty system throughput, n order Outage Probablty n terms of nvestgatng outage probablty, the outage probablty s defned as the occurrence of the stop transmttng event f any nstantaneous bt rate n 8 or can not reach mnmum bt rate thresholds. The probablty densty functon PDf cumulatve dstrbuton functon CDF of Raylegh dstrbuton are showed by, respectvely, f ha,b x = 1 x a,b e a,b dx, 5 F ha,b x = 1 e x a,b, 6 where h a,b are rom ndependent varables namely x n PDF CDF, respectvely, wth a b are source destnaton of channels, a,b s mean of channel ha,b. In generally, the PDF CDF over nakagam-m fadng channels can be expressed, respectvely, f ha,b x = m a,b m x m 1 Γ m e mx a,b, 7 γ m, mx F ha,b x = a,b Γ m mx = 1 e a,b m 1 = mx a,b 1!. 8 In drect lnk scenaro, outage event occurs f UE, where = {1, }, can not decode x, where = {, }. the outage probablty for each of onng UE n OMA system s expressed as Θ Dr = 1 = Pr R x Dr > R. 9 where R Dr x s gven by 8 R s bt rate threshold of UE. By applyng the CDF n 5 7, the 9 s solved t can be rewrtten n closed-form as ℵΘ Dr = 1 = m, m m, RΘ Dr = 1 e = R m R m Γ m + mr χ ρ χ ρ,, 3 χ ρ, Γ m m mr Γ m, Γ m χ ρ,, 31

9 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 9 of 1 where Γ. Γ.,. are gamma Gamma ncomplete functons, R = R 1. It s mportant to notce that 3 31 are wth the users over Raylegh akagam-m fadng channels, respectvely. And, χ n the 3 31 s gven by χ = α R 1 k=1 α k χ = α1 3 wth = {, } or =. Remark 1: Based on our proposed mode wth 1 relayng nodes as Fg. 1, we nvestgate the outage probabltes of number of UE nodes n both HD FD modes as Θ Ω 1 = 1 Pr R Ω l x > R } {{ } η 1 = Pr R x Ω > R } {{ } µ, 33 where η s the successful probablty to detect x symbol at prevous UEs µ s the successful probablty to detect x symbol at th UE. In a specal case of th UE wth = 1, It s mportant to notce that η n 33 s equal wth zero the 33 becomes the same wth 9. In 33, η µ are also solved by applyng the CDF gotten closed-form outage probablty of each UE node over Raylegh fadng channel on both HD FD modes as, respectvely, RΘ HD = RΘ FD = R 1 1 ψ e ρ l 1 l 1,l 1 e R χ ρ 1,, 34 }{{} = }{{} } {{ } A 1 η µ } {{ } A R 1 ψ 1 e ρ l 1 l 1,l ψ ρ l 1 l 1,l ψ ρ l 1 l 1,l + R ρ l h LI,l }{{} }{{} B 1 η 1 e R χ ρ 1 1, χ ρ 1 1, = χ ρ 1 1, + R ρ LI,. 35 }{{} } {{ } B To be clearer, here are some nformaton that should be clearly explaned. We denoted RΘ Ω, where = {1, } Ω = {HD, FD}, s the outage probablty of UE over Raylegh fadng channels. The η symbol n both s the successful detected x symbol at UE l probablty wth l = {1, 1}. Smlarly, the µ symbol n both s the successful detected x symbol at UE. Here are two cases such as: µ

10 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 1 of 1 Frst case wth = 1, η = n both then. And, the outage probablty of UE 1 n HD/FD mode s RΘ Ω = {A, B }. And second case wth > 1, the are wth RΘ Ω = {A 1.B 1, A.B }. In only the second case: ψ n both s gven by Ψ = α R 1 k=l α k. 36 In both cases: χ s gven by 3 after t has been rewrtten as expressed χ = α R 1 α k k= 37 χ = α Remark : The presented results of the studes [3] [4] have frmly contrbuted to the role of OMA system over the Raylegh fadng channels. However, studes on the OMAn system over the akagam-m fadng channels have receved lttle attenton because of ts complexty. Therefore, we nvestgate the outage probablty of each UE over akagam-m fadng channels wth m = on both 1 HD/FD relayng nodes. And, the 33 can be solved by applyng the PDF n 7 whch s expressed n closed-form, respectvely, as ths research contrbutons ℵΘ HD,m= = R 1 ψ 1 e ρ l 1 R + ψ ρ l 1 l 1,l l 1,l ψ ρ l 1 l 1,l }{{} }{{} C 1 η 1 e R R χ ρ 1 1, + χ ρ 1 1, = χ ρ 1 1,, 38 }{{} } {{ } C µ

11 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 11 of 1 ℵΘ FD,m= = R ψ e ρ l 1 l 1,l 1 1 ] ψ ρ l 1 l 1,lψ ρ l 1 l 1,lψ ρ l 1 l 1,l +R +ρ l LI,l R 3ψ ρ l 1 l 1,l +R 3 ψ ρ l 1 l 1,l +ρ lli,l R }{{} }{{} D 1 e R χ ρ 1 1, 1 ] = χ ρ 1 1, χ ρ 1 1, χ ρ 1 1, +R +ρ LI, R 3χ ρ 1 1, +R 3 χ ρ 1 1, +ρ LI, R }{{} } {{ } D η µ 39 There are two cases as descrbed above. It s not necessary to present these cases agan. The analyss results wll be presented n next secton. See appendx for proofng. 3.. System Throughput The achevable receved data at UE, whch s also called system throughput P Ω sum, s sum of throughput results of all UEs n system showed by 3.3. A Proposed for Energy Harvestng P Ω sum = P Ω = 1 Θ Ω =1 =1 R 4 Proposed : In 18 19, the receved sgnals at UE, wth > 1, nclude two parts whch are x k data symbol x empty symbol where k = {, } l = {1, 1}. The x does not contan nformaton. Therefore, we proposed collectng the energy of allocatng power coeffcent of the x symbol for chargng the battery. Another assumpton s that the battery s not lmted by capacty. Thus, the energy harvestng for each UE n both HD FD scenaros are expressed by, respectvely EH = ξ where = {, } ξ s collecton coeffcent A propose an algorthm for -1 relayng nodes 1 α l ρ 1 h 1,, 41 Proposed 3: In ths secton, we propose an algorthm for processng wth 1 relayng nodes as showed n Fg. 1. The treatment flow s done n the waterfall pattern n the order showed n Fg.. 1. Generate a rom UEs n the network wth channels from BS to UEs.. Creatng a lst of channels n descendng order wth the element at the top of the lst s the best channel. Upon completon of the arrangement, BS wll know whch user s best chosen to use for frst hop relayng node.

12 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 1 of 1 3. Through the results of the analyss [3], the authors have found that the performance of the OMA system depends on the effcency of the power allocaton the selecton of the threshold speed accordngly. Lack of channel state nformaton CSI may affect the performance of the OMA system. We have assumed that at BS each UE has full CSI of the other UEs. Based on orderng of SCI as showng n 3, we Allocate the power coeffcents select the bt rate threshold for the UEs as, respectvely where = {1, }, = {, 1}, α = mn,, 4,k k= R = max,, 43,k k= where = {1, }. After the BS dstrbutes the transmt power factor to the UEs, logcally, a superposed sgnal s sent to the nearest UE whch s selected as the frst hop relayng node, namely UE UE 1 receves decodes x symbol wth = {, } by a-1b, excess power s collected by the UE for rechargng. The UE 1 wll select a next relay node by 3 send a superposed sgnal as 18 or 19 to next hop relayng node after UE 1 detects ts own symbol, namely x 1, successfully. Ths work step 4 wll be repeated untl the superposed sgnal wll be transmtted to the last UE, namely UE n model. The outage probablty wll occurrence when x, where = {, }, can not be detected successfully at UE wth = {1, }. 4. umercal Results Dscusson It s mportant to announce that all of our analyss results are smulated by the Matlab software are presented n most accurate clearly. We undertake no reproducton of any pror research results. In addton, n ths study not usng any gven data set. In addton, ths study does not usng any gven data set, channels were generated romly durng the smulaton of a rule. e.g., f there are rom users, the rom channels are arranged accordng to the rule h,1 > h, >... > h, >... > h, 1 > h, the correspondng channel coeffcents 1/1 > 1/ >... > 1/ >... > 1/ 1 > 1/ For the results to be clear accurate, we have performed the Monte Carlo smulaton wth 1e6 rom samples of each h a,b s channels umercal Results Dscusson for Outage Probablty It s mportant to notce that the outage probablty results of Drect, HD FD scenaros are presented by black dashed lnes, red dash-dot lnes, blue sold lnes, respectvely, as showed n Fg. 3a 3b. In the frst case, we assume that there are only three users connected n the network at tth tme slot. We analyzed the performance of the system based on the outage probablty of each user n three dfferent scenaros such as Drect, HD FD schemes. There have some smulaton parameters, e.g., the channel coeffcents h,1 = 1, h, = 1/, h,3 = 1/3 are n accordance wth the earler presented assumptons. Based on the transmsson channel coeffcents of the users, we can allocate power factors for users UE 1, UE, UE 3 wth α 1 =.1818, α =.77, α 3 =.5455, respectvely, wth 3 α = 1 by applyng 4. Because the thrd user, namely UE 3 has the poorest =1 sgnal qualty, t s prortzed to allocate the bggest power factor among the users. Our analyss results showed that users who are far from BS wth poor sgnal qualty have better results, e.g., the outage

13 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 13 of 1 probablty results of the UE the UE 3 are better than the UE 1, although ther sgnal qualty are weaker than the frst one. In addton, the Fg. 3a showed that UE 3 has the outage probablty results whch were marked wth damond marker, are best results compared to the other ones, although U 3 has the weakest sgnal qualty h,3 = 1/3. Because UE 3 receves more collaboraton from the other UEs, the UE 3 s QoS has mproved. Ths result demonstrates the effectveness of our MPCR model. And, the outage probablty results of the frst user, namely UE 1, has worse results than the other UEs, they are the same n all three scenaros, namely Dr, HD FD relayng scenaros. The UE 1 wth the strongest channel coeffcent h,1 = 1 has the worst allocaton power coeffcent α 1 =.1818 compared to the others. A prevous study of FD relayng n [7] the results of comparson between FD HD n [8] showed that the outage probablty the relayng n FD mode was worse than HD one. There s a smlarty n ths research results. The system performance effcency of the MPCR model wth 1 FD relayng nodes has resulted n approxmaton wth 1 HD relayng nodes n the low db SRs. But as the SRs ascendng, the performance of the MPCR system wth -1 HD relayng nodes becomes better demonstrated by the red dash-dot lnes n Fg. 3.a. Specally, although the frst user s outage probablty results n the FD scenaro are the worst, there are not much dfference compared to the other scenaros, such as drect HD scenaros. Ths s because the frst relayng node n FD mode s affected by ts own antenna channel nose, whereas n the drect HD transmsson scenaros wth one antenna have no nterference channels. UEs Channels Allocaton power coeffcents Bt rate thresholds UE 1 h,1 = 1 α 1 =.1818 R 1 =.5455 UE h, =.5 α =.77 R =.77 UE 3 h,3 =.3333 α 3 =.5455 R 3 =.1818 Table 1. 3 UEs n OMA system tth tme slot. To be more clearer, we ncreased the number of users n the network to = 4 users wth the channel coeffcent of UE 4 was h,4 = 1/4 at t+1 tme slot. And, the outage probablty of the users are presented n Fg. 3b. Because the system has a new oned user, namely UE 4, nvolved n the network wth very weak sgnal qualty. Therefore, we reused 4 to reallocate the transmt power factors to the users wth α 1 =.1, α =.16, α 3 =.4, α 4 =.48 as showed n table. And because the power dstrbuton coeffcents have been changed. As a result, the nstantaneous bt rate thresholds of users are also have been changed accordngly. The nstantaneous bt rate thresholds of the user are R = {.48,.4,.16,.1} wth = {1, 4}. In ths case, to ensure the QoS to the fourth user wth the poorest sgnal qualty, we have allocated to ths user the bggest power factor, namely α 4 =.48, the lowest threshold, namely R4 =.1, compared wth other users n the network. In addton, the other users must share power coeffcent to UE 4 n power doman. The compared row contents n table 1 table correspondngly, both α R wth = {1, 3} are reduced for sharng power bt rate to UE 4. As showed n Fg. 3b, although the UE 4 has the poorest sgnal qualty, but t has the best outage probablty results. Ths demonstrates that the MPCR combnes wth allocaton power factor method the nstantaneous bt rate threshold selecton method are effectve. In partcular, the outage probablty results n both HD FD scenaros usng -1 relayng nodes always outperform scheme wth no relayng. Furthermore, we analyze the mpact of both allocaton power coeffcent SRs affect user s servce qualty, especally weak users. In Fg. 3b, the weakest user UE 4 has been assgned a fxed power factor α 4 =.48. I consder f the power allocaton coeffcent for UE 4 ncreases or decreases, the qualty of servce of UE 4 s vared over the correspondng SRs. For smplcty, we assume that

14 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 14 of 1 UEs Channels Allocaton power coeffcents Bt rate thresholds UE 1 h,1 = 1 α 1 =.1 R 1 =.48 UE h, =.5 α = 16 R =.4 UE 3 h,3 =.3333 α 3 =.4 R 3 =.16 UE 4 h,4 =.5 α 4 =.48 R 4 =.1 Table. 4 UEs n OMA system at t+1th tme slot Outage Probablty of 3 UEs Outage Probablty of 4 UEs a DF relayng nodes. b 3 DF relayng nodes. Fgure 3. The outage probablty results of = {3, 4} UEs over Raylegh fadng channels. user UE 4 s over the Raylegh fadng channel. And, the users are over akagam-m fadng channels wll be analyzed later. The Fg. 4 showed the outage probablty of the UE 4 wth the allocaton power factor whch can be varable. We have assumed that the fourth user can be allocated a varable power factor α 4 = {.1,.9} nstead of fxng α 4 =.48 as Fg. 3b. By one-by-one submttng each value α 4 nto 34, 35, 38, 39. It s mportant to notce that the outage probablty results of UE 4 n drect, HD relayng, FD relayng scenaro are presented by sold grd, dashed grd, dash-dot grd. The Fg. The 4 showed that the outage probablty results of UE 4 n HD relayng FD relayng scenaros are better than the UE 4 s results n drect scenaro. Specally, the outage probablty results of UE n MPCR system wth 1 HD/FD relayng nodes are also approxmatons n all SRs. Ths result s consstent wth the results presented earler n Fg. 3a 3b. In addton, we nvestgate outage probablty of users over akagam-m fadng channels scenaro versus the ones over Raylegh fadng channels scenaro as showng n Fg. 5. To ensure that ths comparson s far, the smulaton parameters n the akagam-m fadng channles scenaro are the same as the smulaton parameters showed n table 1. Therefore, t s not necessary to present these smulaton parameters agan. In low SRs, the outage probablty results of the users over Raylegh fadng channels akagam-m fadng channels are approxmated. However, when the SRs are ncreased, the outage probablty results of the user over the akagam-m scenaro are greatly mproved. 4.. umercal Results Dscusson for System Throughput In system performance evaluaton, system throughput s an mportant crteron that s known as the sum of nstantaneous achevable bt rate of each user n the system. We reuse the smulaton parameters as descrbed n the evaluaton of the outage probablty showed n table 1 table. Therefore, we do not restate these parameters. The system throughput of each user wth = 3 UEs = 4 ones are presented n Fg. 6a 6b, respectvely. It s mportant to notce that the sold lnes, dash-dot lnes dashed lnes are the system throughput of the users n drect, HD FD scenaros, respectvely. Because the outage probablty of the users n HD FD scenaros are approxmately equal. As a result, the throughput results of these users are also approxmately equal.

15 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 15 of Drect lnk -1 HD relayng nodes -1 FD relayng nodes Smulaton Drect Smulaton HD Smulaton FD Outage Probablty of 4th UE Fgure 4. The outage probablty results of 4th UE wth α 4 = {.1,.9} SRs = { 1, 3} Outage Probablty of 3 UEs Outage Probablty of 3 UEs a HD relayng nodes. b FD relayng nodes. Fgure 5. The outage probablty results of 3 UEs over Raylegh fadng channels versus akagam-m fadng channels va m = Thus, the dash-dot lnes dashed ones are overlapped n both Fg. 6a 6b. The analyss results showed that the system throughput of users n the 1 HD/FD relayng nodes scenaros are always better than the system throughput of the ones n the non-relay scenaro. Specfcally, the frst UE s system throughput s approxmate n all three scenaros. At SR n 3 db, all users n three scenaros reach ther bt rate thresholds R. On another h, We analyze the mpact of the allocaton power factor α 4 on the fourth user s throughput wth varable α 4 = {.1,.9} values nstead fxng t α 4 =.48. As showng n Fg. 7, hgher grd lnes are better results than the ones. In ths case, the nstantaneous bt rate threshold of UE 4 s R4 =.1 bps/hz. In low SRs, e.g. SR = db, the system throughput results n all scenaros are approxmately zero. On another h, although the SR has ncreased, e.g. SR = 1 db, the system throughput results are stll approxmately zero f the power factor, namely α 4 s stll n low, e.g. α 4 =.1. But wth α 4 =.4 though SR s stll held at 1 db, the system throughput results of UE 4 n both HD FD scenaros are mproved reach ther bt rate threshold. And, n Fg. 6a showed that at SR n 1 db α 4 =.48, the UE 4 reach ts bt rate threshold, approxmately.

16 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 16 of 1 Throughput of 3 UEs Throughput of 4 UEs a = 3 UEs n network. b = 4 UEs n network. Fgure 6. The system throughput results of the users over Raylegh fadng channels. Another e.g., n pared α 4 =.5 SR = db, UE 4 also reach ts bt rate threshold. By ths analyss, we can fnd pars of values α 4 SR where UE 4 can reach the threshold R4 =.1 bps/hz..1 Throughput of 4th UE va Drect lnk a va -1 HD relayng nodes b va -1 FD relayng nodes c Smulaton a Smulaton b Smulaton c System Throughput of 4th UE Fgure 7. The throughput of the 4th UE over Raylegh fadng channels wth α 4 = {.1,.9} SRs = { 1, 3}. The system throughput of the users n 1 HD relayng nodes over both Raylegh akagam-m scenaros were analyzed, compared presented n Fg. 8a. In Fg. 8a, There are = 3 UEs over Raylegh fadng channels akagam-m fadng channels wth sold lnes 3 as showng n Fg. 5a. By applyng 4, we dashed ones, respectvely. Because Θ HD 1 > Θ HD > Θ HD get P HD 1 < P HD < P HD 3 wth low SRs. But as the SR ncreases, the system throughput of each UE changes, e.g. SR = 3 db, P1 HD > P HD > P3 HD reach ther bt rate thresholds R. The smlarly results happen n 1 FD relayng nodes scheme as showng n Fg. 8b. Specally, because the users over agam-m fadng channels have better outage probablty results than the ones over the Raylegh fadng channels as showng n Fg. 5b, n some SRs, e.g., SR = 1 db then ℵΘ FD < RΘ FD. Therefore, ℵP FD > RP FD where ℵ R were denoted as akagam-m Raylegh fadng channels, respectvely, after we appled 4. these results proved that the akagam-m channel

17 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 17 of System Throughput of 3 UEs.4.3. System Throughput of 3 UEs a -1 HD relayng nodes. b -1 FD relayng nodes. Fgure 8. Compared the system throughput results of Raylegh versus akagam-m va m=. s better than the Raylegh channel. However, when we are ncreasng SRs, there have approxmately the same results close to the thresholds ℵP HD RP HD R UEs wth -1 HD/FD Relayng odes As models n Fg. 1a b, the proposed algorthm 1 can nvestgate the system performance wth UEs where s a rom bg number. Because of the lmted power of our personal computers, we only analyze present cases where there are only 3 or 4 users n the system. But the results presented do not show all the advantages of our algorthm. Thus, we are ncreasng lmt the number user wth bgger number. As Fg. 9a b, there have 9 UEs n the network. By applyng algorthm 1, we nvestgated the outage probablty of the UEs n the network over both Raylegh akagam-m fadng channels. For e.g., n 1 HD relayng nodes scenaro, the outage probablty of the frst UE, namely UE 1, can be calculated by 34 or 8 over Raylegh or akagam-m fadng channels wth m =, respectvely, where η =. Another e.g., n FD scenaro, the outage probablty of last UEs, namely UE 9, over Raylegh or akamagm-m fadng channels can be computed by 35 or 39, respectvely. Wth the number of users s greater than 9, the results of the analyss are dffcult to observe n the fgure t need more tme for the smulaton so we end our analyss wth up to 9 users n network Outage Probablty of 9 UEs Outage Probablty of 9 UEs a 9 UEs n 8 HD relayng nodes model. b 9 UEs n 8 FD relayng nodes model. Fgure 9. Compared the outage probablty results of Raylegh versus akagam-m fadng channels

18 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 18 of 1 5. Concluson In ths study, we proposed a novel OMA network model wth 1 relayng nodes nstead of usng only one relay as prevous studes. A superposed sgnal would be sent through 1 relayng nodes before t reaches the farthest UE whch s denoted by UE. The closed-form expressons of 1 HD/FD relayng nodes scenaros over Raylegh/akagam-m fadng channels are also presented along wth an explanaton for the correspondng processng. By presentng results n the fgures, our proposed models wth 1 HD/FD relayng nodes are effectve for applyng to the cooperator OMA network n next generaton wreless telecommuncatons. Author Contrbutons: T-T s the frst author who has proposed the man dea, analyzed smulated the system, presented the wrtng orgnal draft preparaton, wrtng revew edtng, vsualzaton. MV are the second thrd authors who has experences n wreless communcaton research. They have made a supervson, revew, gven the frst author some useful comments fundng acquston for ths research. All authors read approved the fnal manuscrpt. Fundng: Ths research receved no external fundng. Acknowledgments: /A Conflcts of Interest: We declare no conflct of nterest. The funders had no role n the desgn of the study; n the collecton, analyses, or nterpretaton of data; n the wrtng of the manuscrpt, or n the decson to publsh the results. Abbrevatons The followng abbrevatons are used n ths manuscrpt: o. Abbrevatons Full descrpton 1 AWGs Addtve whte Gaussan noses BS Base staton 3 CDF Cummuatve dstrbuton functon 4 CSI Channel state nformaton 5 Fg. Fgure 6 OMA non-orthogonal multple access 7 OFDMA Orthogonal frequency-dvson multple access 8 PDF Probablty densty functon 9 QoS Qualty of servce 1 S Source 11 SIC Successve nterference cancellaton 1 SIR Sgnal-to-nterference-plus-nose rato 13 SR Sgnal-to-nose rato 14 UEs User Equpments Table 3. The abbrevatons table. Proof of 1 HD relayng nodes scenaro: The condton for occurrence of the outage events has been presented n 33. By submttng, where Ω = HD, nto 33, we can get a expresson for computng the outage probablty of each UE n 1 HD relayng nodes scenaro. Θ HD = 1 1 hl 1,l Pr > R χ ρ l 1 1 = Pr h 1, > R χ ρ 1 The A1 can be rewrtten n expermental ntegral by applyng the PDF 5 of Raylegh dstrbutons as A1

19 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 19 of 1 RΘ HD = 1 1 R χ ρ l 1 1 l 1,l e x l 1,l dx 1 = R χ ρ 1 1 1, e x 1, dx. A The A can be solved expressed as 34. On another h, the A can be wrtten wth the PDF 7 of akagam-m fadng channels as ℵΘ HD = 1 1 R χ ρ l 1 m l 1,l m x m 1 Γ m e mx l 1,l dx 1 after the A3 was solved, t can be expressed as 38. = R χ ρ 1 1 1, m x m 1 Γ m e mx 1, dx Proof of 1 FD relayng nodes scenaro: In smlarly, by submttng??, where Ω = FD, nto 33, we can get a expresson for computng the outage probablty of each UE n 1 FD relayng nodes scenaro. A3 Θ FD = = Pr Pr R hl 1,l > h 1, > R hl,l ρl + 1, hl,l > χ ρ l 1 h L, ρ + 1, h χ ρ L, > 1 A4 The A4 s also rewrtten n expermental ntegral by applyng the PDF of Raylegh or akagam-m fadng whch are respectvely 5 or 7, respectvely, as RΘ HD = = R yρ l +1 χ ρ l 1 R yρ +1 χ ρ 1 1 l 1,l LI,l 1 1, LI, e e x l 1,l + y LI,l x 1, + y LI, dxdy dxdy. A5

20 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 of 1 ℵΘ FD = = R yρ l +1 χ ρ l 1 R yρ +1 χ ρ 1 m l 1,l LI,l m 1, LI, m xy m 1 Γ m e m m xy m 1 Γ m e m x l 1,l + y LI,l x 1, + y LI, dxdy dxdy A6 For e.g. m =, the A5 A6 are solved expressed as 38 39, respectvely. End of proof. References 1. Y. Sato, A. Benebbour, Y. Kshyama T. akamura, "System-level performance evaluaton of downlnk non-orthogonal multple access OMA", 13 IEEE 4th Annual Internatonal Symposum on Personal, Indoor, Moble Rado Communcatons PIMRC, 13.. Z. Dng, Z. Yang, P. Fan H. Poor, "On the Performance of on-orthogonal Multple Access n 5G Systems wth Romly Deployed Users", IEEE Sgnal Processng Letters, vol. 1, no. 1, pp , Y. Lan, A. Benebbou, X. Chen, A. L H. Jang, "Consderatons on downlnk non-orthogonal multple access OMA combned wth closed-loop SU-MIMO", 14 8th Internatonal Conference on Sgnal Processng Communcaton Systems ICSPCS, Z. Dng, M. Peng H. Poor, "Cooperatve on-orthogonal Multple Access n 5G Systems", IEEE Communcatons Letters, vol. 19, no. 8, pp , Y. Xao, L. Hao, Z. Ma, Z. Dng, Z. Zhang P. Fan, "Forwardng Strategy Selecton n Dual-Hop OMA Relayng Systems", IEEE Communcatons Letters, vol., no. 8, pp , A. Davood, M. Emad M. Aref, "Analytcal power allocaton for a full duplex decode--forward relay channel", 13 Iran Workshop on Communcaton Informaton Theory, Z. Dng, H. Da H. Poor, "Relay Selecton for Cooperatve OMA", IEEE Wreless Communcatons Letters, vol. 5, no. 4, pp , H. Gao, W. Eaz M. Jo, "Cooperatve Wreless Energy Harvestng Spectrum Sharng n 5G etworks", IEEE Access, vol. 4, pp , A. Tonello, F. Versolatto S. D Alessro, "Opportunstc Relayng n In-Home PLC etworks", 1 IEEE Global Telecommuncatons Conference GLOBECOM 1, L. Lampe A. Vnck, Cooperatve multhop power lne communcatons, IEEE Int. Symp. Power Lne Commun. Its Appl. ISPLC, pp. 1 6, Mar X. Cheng, R. Cao, L. Yang, Relay-aded amplfy--forward powerlne communcatons, IEEE Trans. Smart Grd, vol. 4, pp. 65 7, Mar K. Rabe, B. Adebs, H. Gacann, G. auryzbayev A. Ikpeha, "Performance evaluaton of mult-hop relayng over non-gaussan PLC channels", Journal of Communcatons etworks, vol. 19, no. 5, pp , A. Dubey, R. K. Mallk, R. Schober, Performance analyss of a mult-hop power lne communcaton system over log-normal fadng n presence of mpulsve nose, IET Commun., vol. 9, no. 1, pp. 1 9, A. Dubey R. K. Mallk, PLC system performance wth AF relayng, IEEE Trans. Commun., vol. 63, pp , Jun Z. Dng, H. Da H. Poor, "Relay Selecton for Cooperatve OMA", IEEE Wreless Communcatons Letters, vol. 5, no. 4, pp , X. Lu, P. Wang, D. yato, D. I. Km, Z. Han, Wreless networks wth RF energy harvestng: A contemporary survey, IEEE Commun. Surveys Tuts., vol. 17, pp , 15.

21 Preprnts OT PEER-REVIEWED Posted: 1 December 18 do:1.944/preprnts v1 1 of A. A. asr, H. D. Tuan, D. T. go, S. Durran, D. I. Km, Path-followng algorthms for beamformng sgnal splttng n RF energy harvestng networks, IEEE Commun. Letters, vol., no. 8, pp , Aug V. D. guyen, T. Q. Duong, H. D. Tuan, O. S. Shn, H. V. Poor, Spectral energy effcences n full-duplex wreless nformaton power transfer, IEEE Trans. Commun., vol. 65, no. 5, pp. 33, May H. H. M. Tam, H. D. Tuan, A. A. asr, T. Q. Duong, H. V. Poor, MIMO energy harvestng n full-duplex mult-user networks, IEEE Trans. Wrel. Commun., vol. 16, no. 5, pp , May 17.. A. A. asr, H. D. Tuan, T. Q. Duong, H. V. Poor, Secrecy rate beamformng for multcell networks wth nformaton energy harvestng, IEEE Trans. Sgnal Process., vol. 65, no. 3, pp , K. HIGUCHI A. BEJEBBOUR, "on-orthogonal Multple Access OMA wth Successve Interference Cancellaton for Future Rado Access", IEICE Transactons on Communcatons, vol. 98, no. 3, pp , 15.. Y. Jng H. Jafarkhan, Sngle multple relay selecton schemes ther achevable dversty orders, IEEE Transactons on Wreless Communcatons, vol. 8, no. 3, pp , Mar Dng, H. Da H. Poor, "Relay Selecton for Cooperatve OMA", IEEE Wreless Communcatons Letters, vol. 5, no. 4, pp , Km I. Lee, "Capacty Analyss of Cooperatve Relayng Systems Usng on-orthogonal Multple Access", IEEE Communcatons Letters, vol. 19, no. 11, pp , A. K. Sadek, Z. Han, K. J. R. Lu, A dstrbuted relay-assgnment algorthm for cooperatve communcatons n wreless networks," IEEE Int. Conf. Commun., Istanbul, Turkey, June V. Sreng, H. Yankomeroglu, D. D. Falconer, Relay selecton strateges n cellular networks wth peer-to-peer relayng," n Proc. IEEE Veh. Technol. Conf., Orlo, FL, Oct T. Thanh-am, D. Dnh-Thuan, M. Voznak, Full-duplex Cogntve Rado OMA etworks: Outage Throughput Performance Analyss," n Proc. Internatonal Journal of Electroncs Telecommuncatons, vol. 65, no. 1, T. Thanh-am, D. Dnh-Thuan, M. Voznak, On Outage Probablty Throughput Performance of Cogntve Rado Inspred OMA Relay System," n Proc. Advances n Electrcal Electronc Engneerng, 19. About the Authors... am T. TRA was born n Vnh Long provnce, Vetnam. He receved hs M.Sc. from Mltary Techncal Academy MTA n 14. He works n the faculty of Electroncs Telecommuncatons, Sa Gon Unversty, Ho Ch Mnh cty, Vet am. He s currently pursung hs Ph.D. degree n Electrcal Engneerng at VSB Techncal Unversty of Ostrava, Czech Republc. Hs maor nterests are n OMA, energy harvestng, cogntve rado, physcal layer securty. Mroslav VOZAK receved the Ph.D.degree n telecommuncatons from the Faculty of Electrcal Engneerng Computer Scence, VSB-Techncal Unversty of Ostrava completed hs habltaton n 9, respectvely. He was apponted Full Professor n 17 n Electroncs Communcaton technologes. He s an IEEE senor member he has served as a member of edtoral boards for several ournals, such as the Journal of Communcatons or the Advances n Electrcal Electronc Engneerng. Hs research nterests focus generally on nformaton communcatons technology, partcularly on qualty of servce experence, network securty, wreless networks n the last couple years also on bg data analytcs.