Resource Allocation in Visible Light Communication Networks NOMA vs. OFDMA Transmission Techniques

Transcription

1 Resource Allocaion in Visible Ligh Communicaion Neworks NOMA vs. OFDMA Transmission Techniques Eirini Eleni Tsiropoulou, Iakovos Gialagkolidis, Panagiois Vamvakas, and Symeon Papavassiliou Insiue of Communicaions & Compuer Sysems (ICCS) School of Elecrical & Compuer Engineering Naional Technical Universiy of Ahens (NTUA) Erik Jonsson School of Engineering School & Compuer Science Universiy of Texas a Dallas 1

2 Presenaion Agenda Inroducory Remarks Paper Conribuion VPANs Topology and Sysem Model OFDMA vs. NOMA Opical Access Poin Selecion Uiliy Funcions Problem Formulaion and Soluion Approach NOAPRA Algorihm Numerical Resuls Takeaways 2

3 Presenaion Agenda Inroducory Remarks Paper Conribuion VPANs Topology and Sysem Model OFDMA vs. NOMA Opical Access Poin Selecion Uiliy Funcions Problem Formulaion and Soluion Approach NOAPRA Algorihm Numerical Resuls Takeaways 3

4 Inroducory Remarks Visible Ligh Communicaions Personal Area Neworks (VPANs) The communicaion signal is encoded on op of he illuminaion ligh Energy saving green communicaion High Speed Conneciviy Poenial No healh hazards, reduced inerference and low ransmission power a almos no cos Resource Allocaion Disribued Approach No cenrally deermined: he decision lies a he mobile erminals Opimal OAPs Selecion wihin he users, Resource Blocks (RBs) and Uplink Transmission Power allocaion based on Maximum Gain Policy and Uiliy Maximizaion 4

5 Presenaion Agenda Inroducory Remarks Paper Conribuion VPANs Topology and Sysem Model OFDMA vs. NOMA Opical Access Poin Selecion Uiliy Funcions Problem Formulaion and Soluion Approach NOAPRA Algorihm Numerical Resuls Takeaways 5

6 Paper Conribuion Self Opimizaion The users opimally deermine heir ransmission parameers irrespecive of he seleced ransmission echnique Topology Opimizaion and Opimized User Transmission OAP selecion Uplink Transmission Power Allocaion Power Allocaion in he Uplink of VPANs One of he firs approaches in lieraure, so far only downlink ransmission was examined NOMA Presenaion of NOMA (Non Orhogonal Muliple Access) as a new promising ransmission echnique for resource allocaion in he 5G neworking era Exensive Comparisons NOMA is in deph compared wih OFDMA (Orhogonal Frequency Division Muliple Access) Advanages and Disadvanages - Conclusions 6

7 Presenaion Agenda Inroducory Remarks Paper Conribuion VPANs Topology and Sysem Model OFDMA vs. NOMA Opical Access Poin Selecion Uiliy Funcions Problem Formulaion and Soluion Approach NOAPRA Algorihm Numerical Resuls Takeaways 7

8 VPANs Topology & Sysem Model Muli-cell VPAN nework consising of T OAPs T U Mobile Users A specrum of oal bandwidh W is devoed o each OAP 1,2,..., T U u1,2,..., U Simple VPAN opology Each user u communicaes wih an OAP via a communicaion link l u, Line of Sigh (LOS) beween he user and he OAP: m1 A m cos 2 Ts g cos, 0 c Hu, 2 d A: phoodeecor area φ: irradiance angle T s (ψ): signal ransmission coefficien of an opical filer ψ: angle of incidence m: order of Lamberian emission g(ψ): gain of an opical concenraor d: disance beween he OAP and he user 0, oherwise 8

9 Presenaion Agenda Inroducory Remarks Paper Conribuion VPANs Topology and Sysem Model OFDMA vs. NOMA Opical Access Poin Selecion Uiliy Funcions Problem Formulaion and Soluion Approach NOAPRA Algorihm Numerical Resuls Takeaways 9

10 SINR (γ) OFDMA vs. NOMA Orhogonal Frequency Division Muliple Access (OFDMA) The bandwidh of each Opical Access Poin is divided ino subcarriers, organized ino Resource Blocks Each Resource Block is reserved for one user wihin he OAP, and reused among differen OAPs Co-channel inerference caused by reuse of RBs from differen OAPs Non-Orhogonal Muliple Access (NOMA) Users wihin he same OAP simulaneously exploi he whole bandwidh, leading o considerable achievable rae enhancemens Each user decodes only he signals of oher users wih beer channel gain (SIC inerference cancellaion echnique) Inerference from users wih worse channel gain is reaed as noise (r) u, U u1, uu, T R H P ( r) PD u, u, H P ( r) u, u, R PD : phoodiode responsiiviy H u, : line of sie pah gain beween user and he OAP P u, : user s uplink ransmission power ξ: cumulaive noise power u, U uu, T R H P PD u, u, H P u, u, 10

11 Presenaion Agenda Inroducory Remarks Paper Conribuion VPANs Topology and Sysem Model OFDMA vs. NOMA Opical Access Poin Selecion Uiliy Funcions Problem Formulaion and Soluion Approach NOAPRA Algorihm Numerical Resuls Takeaways 11

12 Opical Access Poin Selecion A mobile user may reside wihin muliple OAPs Maximum Gain Selecion (MGS) Policy: Each user wihin he VPAN selec he OAP ha provides he highes pah Gain H beween him and he OAP Near Opimal Soluion: Each user achieves he bes feasible channel condiions based on he line of sigh channel gain H, Channel gain diversiy Perfec pah gain knowledge necessary H H... H H2,1 H2,2.... H ( u, ) H H... H 1,1 1,2 1, T U,1 U,2 U, T l * * * u, arg max T H u, Users wihin an OAP vary wih ime, hus he MGS problem for OAP selecion should be solved periodically per ime slo 12

13 Presenaion Agenda Inroducory Remarks Paper Conribuion VPANs Topology and Sysem Model OFDMA vs. NOMA Opical Access Poin Selecion Uiliy Funcions Problem Formulaion and Soluion Approach NOAPRA Algorihm Numerical Resuls Takeaways 13

14 Uiliy Funcions Uiliy Funcions Reflec users degree of saisfacion as a resul of heir acions A user arges a ransmiing wih low uplink ransmission power: Enhanced baery life Less inerference in he muli-cell VPAN environmen Saisfacion increases wih high ransmission daa rae and lower ransmission power values Uiliy funcions show he rade-off beween he among parameers OFDMA : NOMA : U U u, r u, u, W fu N P W fu P r u, r u, u, N : number of users wihin he OAP W: OAP s bandwidh f u ( ): efficiency funcion - represens he probabiliy of successful packe ransmission 14

15 Presenaion Agenda Inroducory Remarks Paper Conribuion VPANs Topology and Sysem Model OFDMA vs. NOMA Opical Access Poin Selecion Uiliy Funcions Problem Formulaion and Soluion Approach NOAPRA Algorihm Numerical Resuls Takeaways 15

16 Problem Formulaion and Soluion Approach (1/2) Objecive Each user acing selfishly arges a maximizing his overall perceived saisfacion (uiliy) hrough an opimally deermined ransmission power value via a disribued approach Uplink Power Allocaion Problem Formulaion r P u, P -u, P-u, r r r OFDMA : max U P, NOMA : max U P, u, u, u, u, P P s.. 0 P s.. 0 P P Max r u, Max u, u, u, Ru, u, The firs approach owards uplink ransmission power allocaion in VPANs alongside QoS provisioning Opimizaion Soluion Approach Firs order derivaive of he uiliies: U P r u, r u, u, resp r fu u, r r 0 u, fu u, 0 r U f u, u u,. 0 u, fu u, 0 Pu, u, 16

17 Problem Formulaion and Soluion Approach (2/2) Unique Soluion Unique Soluion due o sigmoidal form of f(γ) and one-o-one SINR funcion for boh OFDMA and NOMA ransmission echniques OFDMA : U r* ( r) u, Hu, Pu, u1 uu Max r* Pu, Pu, min T, RPDHu, Ru NOMA : U * u, Hu, Pu, uu * Max Pu, min T, Pu, RPDHu, P * P Opimal Uplink Transmission Power Vecors P, P,..., P,..., P ( )* ( )* ( )* ( )* ( )* 1, 2, u, U, P, P,..., P,..., P * * * * 1, 2, u, U, 17

18 Presenaion Agenda Inroducory Remarks Paper Conribuion VPANs Topology and Sysem Model OFDMA vs. NOMA Opical Access Poin Selecion Uiliy Funcions Problem Formulaion and Soluion Approach NOAPRA Algorihm Numerical Resuls Takeaways 18

19 OAP Selecion Par NOAPRA Algorihm (1/2) NOAPRA Non-Cooperaive OAP Selecion and Resource Allocaion Algorihm: Decenralized, ieraive, disribued, and low complexiy - divided in wo pars Based on Maximum Gain Selecion Policy, he Marix H(u,) is creaed, given perfec knowledge of pah gain informaion. Se k=1 and U (0) ={1,2,,U} Sep A 1 Each user u* connecs o he OAP, via creaing a communicaion link based on he highes pah gain H u, * * * * * l u, arg max u U, T H u, Delee user u* from he overall se of users: U (k+1) = U (k) -{u * } (k 1) U If hen sop. Oherwise go o Sep 2 Sep A2 Sep A3 Sep A4 19

20 Resource Allocaion Par Uplink Transmission Power Allocaion RB s Allocaion (OFDMA) NOAPRA Algorihm (2/2) Each OAP is aware of he number of users residing wihin i (i.e., U) Sep B1 If R=U: one Resource Block r R is allocaed per user uu Sep B2 Each user wihin an OAP iniially ransmis wih a randomly seleced feasible uplink ransmission power and se k=0: (OFDMA) 0 P *(r)(0) u, P Max u, R u, (NOMA) 0 P P *(0) Max u, u, The conroller collecs he informaion and each OAP announces he overall inerference o he users. Each one user compues his sensed inerference Given he overall inerference, each user updaes his uplink ransmission power. Se k=k+1 10 *(r)( k1) *(r)( k) *( k1) *( k) If Pu, Pu, (resp. Pu, Pu, ), e.g., hen Sop Oherwise go o sep 2. 5 Sep C1 Sep C2 Sep C3 Sep C4 20

21 Presenaion Agenda Inroducory Remarks Paper Conribuion VPANs Topology and Sysem Model OFDMA vs. NOMA Opical Access Poin Selecion Uiliy Funcions Problem Formulaion and Soluion Approach NOAPRA Algorihm Numerical Resuls Takeaways 21

22 Simulaion Scenario Numerical Resuls Case 1: Uniform Disribuion (7 users per OAP) VPAN nework wih 8 OAPs wihin a room of size 10m x 6m x 3m OFDMA: 7 Resource Blocks are available P max =1W W OAP =20 MHz N oal = 56 users Case 2: Non-Uniform Users Disribuion 22

23 Users Average Uplink Transmission Power per OAP Case 1: Uniform Disribuion Case 2: Non-Uniform Disribuion In OFDMA, uplink ransmission power considerably increases in non uniform user disribuion since users share he same resource blocks wihin differen OAPs, causing much higher inerference In NOMA, increase in uplink ransmission power for non uniform disribuion is smooher due o he inerference cancellaion echnique 23

24 Sysem s Toal Uplink Transmission Power and Rae for Increasing Number of Users In OFDMA, due o he fixed number of reusable RBs, he sysem canno suppor more han 56 users, hus any addiional users are rejeced. Transmission power and rae remain consan In NOMA, he sysem can accommodae and serve a much larger number of users providing superior daa rae poenial 24

25 Users Average Uplink Transmission Rae Case 1: Uniform Disribuion Case 2: Non-Uniform Disribuion In NOMA, uplink ransmission rae is considerably higher han OFDMA since he users can exploi he whole bandwidh, regardless of he user disribuion wihin he nework 25

26 Presenaion Agenda Inroducory Remarks Paper Conribuion VPANs Topology and Sysem Model OFDMA vs. NOMA Opical Access Poin Selecion Uiliy Funcions Problem Formulaion and Soluion Approach NOAPRA Algorihm Numerical Resuls Takeaways 26

27 Takeaways Opimal Opical Access Poin selecion alongside Transmission Power Allocaion in he Uplink of VPANs under various ransmission echniques Visible Ligh Communicaions a promising wireless echnology: Ulrahigh ransmission speeds Decreased users ransmission power No hrea o human healh NOMA All users can simulaneously exploi he whole bandwidh Considerable inerference miigaion NOMA vs. OFDMA NOMA can provide users wih beer service qualiy han OFDMA due o he inerference miigaion (SIC) echnique, regardless of he user disribuion wih he nework Due o he absence of Resource Blocks per user, NOMA can sufficienly accommodae more users han OFDMA 27

28 Resource Allocaion in Visible Ligh Communicaion Neworks NOMA vs. OFDMA Transmission Techniques Thank you for your aenion! 28