Scholars Joural of Egieerig ad Techology (SJET) Sch. J. Eg. Tech., 06; 4(4):69-74 Scholars Academic ad Scietific Publisher (A Iteratioal Publisher for Academic ad Scietific Resources) www.sasublisher.com ISSN 3-435X (Olie) ISSN 347-953 (Prit) Research Article Priority Based Balacig Model of Resource Allocatio i LTE Dowlik Oleksadr V. Lemeshko, Ayme M. Al-Dulaimi Telecommuicatio Systems Deartmet, Odesa Natioal Academy of Telecommuicatios amed after O.S. Poov, Ukraie, 6509, Odesa, Kovalska St. *Corresodig author Oleksadr V. Lemeshko Email: avlem@ukr.et Abstract: Ivestigatio of riority based balacig model of resource allocatio i LTE dowlik suortig RAT reseted. The ovelty of model is that it ca be used to describe the rocess of resource blocks allocatio i LTE dowlik give user equimets requests riority. Usig the model allows to otimize the rocess of resource allocatio i LTE dowlik i solvig the roblem by mixed-iteger liear rogrammig. The advatage of the model is that the balacig of resource blocks umber allocated to each of user equimets is erformed based o QoS requiremets: demaded bit rate, riority ad resource tye (with or without guaratee). Results of research cofirmed the efficiecy of model ad adequacy of obtaied o its basis solutios. Keywords: LTE; dowlik; resource block; allocatio; otimizatio; model. INTRODUCTION Nowadays LTE (Log-Term Evolutio) techology ca be alied i etwork solutios rovidig a wide rage of differet ifo commuicatio services [, ] both delay sesitive real-time services as well as data commuicatio. It should be oted, that these services have higher requiremets for etwork resources: badwidth, allowable values of average acket delay ad degree of their losses. That s why otimizatio of rocesses Resource Blocks Allocatio is a effective facility of imrovig Quality of Service (QoS) i LTE etwork [, 3-5]. Resource Blocks (s) are timefrequecy resources combied i Resource Block Grous (G) i imlemetatio of differet Resource Allocatio Tyes (RAT); i solvig the roblem of resource blocks allocatio the followig must be take ito accout: available resource is determied by the frequecy chael badwidth ad oeratio mode of etwork equimet; i accordace with the stadard [] resource allocatio imlemeted as oe of three tyes (RAT 0 ); Decisios o resource allocatio must esure balaced s allocatio amog User Equimets (UEs) due to their QoS requiremets ad service riority. I this research roosed ad ivestigated riority based balacig model of resource allocatio i LTE dowlik suortig RAT with develomet ad further imrovemet of solutios roosed i [6-8] usig UEs riorities for better esurig QoS-requiremets. BALANCING MODEL OF RESOURCE BLOCKS ALLOCATION IN LTE DOWNLINK USING RAT With the usig of RAT the set of resource blocks is divided ito several o-overlaig subsets, the umber of which ( N ) is determied by G size ( P arameter):, if N 0;, if N 6; P () 3, if N 7 63; 4, if N 64 0. The umber of s i subsets may vary. I [, ] roosed the followig exressio to determie the umber of s i subsets i LTE: 69
Lemeshko OV et al., Sch. J. Eg. Tech., Aril 06; 4(4):69-74 N P P, P N at mod P; P N P N mod, P P Gsubset N ( ) () N at mod P; P N P, P N at mod P, P Gsubset Where N ( ) is ower of the -th subset; is a curret umber of s i subset for which calculatio of ower is erformed ( 0, P ); N is the umber of s formed durig trasmissio of oe time slot. I LTE techology the umber of s deeds o the frequecy chael badwidth ad ca be equal to 6, 5, 5, 50, 75, ad 00. I roosed model assumed that the followig iitial data are kow: N is the umber of UEs; K s is the umber of subcarriers for data trasmissio i a sigle. This arameter deeds o the frequecy diversio betwee subcarriers f ad it must satisfy the term K s f 80 KHz. K s ca be equal to ad 4, that already corresod to the frequecy diversio betwee subcarriers f as 5 KHz ad 7.5 KHz; N symb Is the umber of symbols that form a sigle resource block. Parameter N symb =7 i case of usig ormal cyclic refix (CP). Duratio of the ormal CP of the first OFDM symbol is T CP =5. µs, from secod to 6 sixth OFDM symbol it is T CP =4.7 µs. Whe usig the exteded CP ( T CP =6.7 µs) cosists of six OFDM symbols ( N symb =6); T T = ms is time of oe trasmissio; SF = ms is time of oe subframe trasmissio; SF N = is the umber of s that are formed o the idetical subcarriers ad are allocated to UE durig the trasmissio of oe subframe; R is the rate of code used i codig a sigal of the -th UE; c b k is bit symbol load of the -th UE; tye of chael divisio (FDD or TDD), ad frame cofiguratio used; R req is the required data bit rate for -th UE; K is the umber of subframes used to trasmit iformatio i the dowlik. Whe usig FDD the umber of dowlik subframes is equal to the total umber of subframes er frame ( K =0). Whe usig TDD the umber of dowlik subframes must be used accordig to the frame cofiguratio; Gsubset M max( N ) is the largest umber of resource blocks belogig to ay subset. 70
Lemeshko OV et al., Sch. J. Eg. Tech., Aril 06; 4(4):69-74 For solvig the roblem of badwidth allocatio i LTE dowlik with RAT withi the roosed model it is eeded to rovide the calculatio of Boolea cotrol variable ( m x, ), that determies the order of resource blocks allocatio:,, if the m th o the th subset is allocated to the th UE; x m (3) 0, otherwise, where m 0, M ; 0, P ;, N. Whe calculatig the desired variables m x, the term of allocatig each resource block to oly oe user equimet: N x several imortat terms-limitatios should be fulfilled:, ( m 0, M, 0, P ), (4) the term of allocatig -th user equimet a umber of resource blocks of oly oe subset, which is itroduced to satisfy the secifics of desigig the LTE dowlik that uses RAT : x M P M j0, t0, j tm x t, j M For m 0, M ; 0, P ;, N ; (5) the term of allocatig a umber of resource blocks to -th user equimet that rovide the required badwidth i the dowlik usig modulatio ad codig scheme (MCS): M P m0 0, m req x r R, (, N ), (6) NsymbN SF K S Rc kb K where r, m is badwidth allocated by m-th o the -th subset to -th UE; 0T SF, if for thue service guaratee ecessary; 0, otherwise. For otimal balacig the umber of s allocated to each UE, the system itroduced additioal coditios limitatios to the cotrol variables x, : m M P r, m m0 0 req ( Pr ) x R, (, N ), (7) where is a cotrol variable too, characterizig lower boud of satisfactio level of QoS requiremets to bit rate; is the -th user equimet riority (Table I). Table : Stadardized QoS Class Idetifier (QCI) characteristics [] QCI Resource Priority Packet Delay Packet Error Loss Tye Level Budget Rate Examle Services 00 ms 0 - Coversatioal Voice 4 50 ms 0-3 Coversatioal Video (Live Streamig) 3 Guarateed 3 50 ms 0-3 Real Time Gamig 4 Bit Rate 5 300 ms 0-6 No-Coversatioal Video 65 (GBR) 75 ms 0 - Missio Critical user lae Push To Talk voice 66 00 ms 0 - No-Missio-Critical user lae Push To Talk voice 5 00 ms 0-6 IMS Sigallig 6 6 300 ms 0-6 Video, (Buffered Streamig), TCP-based 7 No 7 00 ms 0-3 Voice, Video (Live Streamig), Iteractive Gamig 8 Guarateed 8 Bit Rate 300 ms 0-6 Video (Buffered Streamig), 9 9 TCP-based 69 60 ms 0-6 Missio Critical delay sesitive sigallig 70 5.5 00 ms 0-6 Missio Critical Data Pr 7
Lemeshko OV et al., Sch. J. Eg. Tech., Aril 06; 4(4):69-74 The followig restrictios imosed to the itroduced variable 0. (8) To imrove the quality of service i LTE etwork i solvig the roblem of balacig the umber of s allocated to UEs it is eeded to maximize the lower boud meetig QoS requiremets to bit rate, i.e. max x,. (9) Thus, the model of balacig the umber of s allocated to UEs i LTE dowlik based o solutio of otimizatio roblem associated with maximizig the lower level allocated badwidth to each user equimet (9) accordig to its QoS requiremets for bit rate (6). As the costraits stated i solvig the otimizatio roblem are coditios (3)-(8). Formulated otimizatio roblem belogs to class of mixed-iteger liear rogrammig, because some variables of (3) are Boolea, balacig variable (8) is a ositive real variable, ad objective fuctio (9) ad costraits (4)-(8) are liear. INVESTIGATION OF BALANCING MODEL OF RESOURCE BLOCKS ALLOCATION IN LTE DOWNLINK Withi the ivestigatio were cosidered the followig iut data: umber of UEs is 4 ( N 4); chael badwidth 3 MHz; umber of s is 6 ( N 6 ); 3 4 bit rates required for each of the UEs are R req 3 Mbs, R req 3 Mbs, R req 3 Mbs, R req 3 Mbs; UEs riorities ( Pr, Pr 3, Pr 5, Pr 7 ); 3 4 all UEs with No GBR resource tye; Gsubset umber of s i subsets M max( N ) 8 (0 7); matrices of s badwidths for subsets 0 ad UEs 4: 0 0.6 0. 0.6 r, k, 0.8 0.9 0.6 0.8 0.9 0. 0. 0. 0. 0.6 0. 0.6 0 r, k. 0.8 0.9 0.6 0.8 0 0 0 Results of usig model ()-(9) for solvig roblem of badwidth allocatio i LTE dowlik with Resource Allocatio Tye based o the use of otimality criterio (9) show i Table II. Durig maximizatio of criterio (9) obtaied the followig results: first ad third UEs use zero subset, while secod ad fourth UEs use the first subset; totally used 5 resource blocks; Procedure of badwidth allocatio for each UE is followig:.6 Mbs,.5 Mbs, Mbs, ad 0.8 Mbs. There are umbers of UEs usig oe or other show i rows Subset 0 ad Subset i Table II. Bitma for first UE ad result of resource blocks allocatio to all UEs with o GBR show o Fig.. 7
Lemeshko OV et al., Sch. J. Eg. Tech., Aril 06; 4(4):69-74 Table : Procedure of Resource Blocks Allocatio to UEs (All UEs with No GBR) 0 3 4 5 6 7 G 0 3 Subset 0 Subset 4 3 3 8 9 0 3 4 G 4 5 6 7 Subset 0 Subset 4 Fig-: Bitma for first UE ad Result of Resource Blocks Allocatio to all UEs with No GBR As show i Table II, LTE dowlik resource has bee allocated amog the four UEs accordig to their requiremets for bit rate ( R req ) ad riority level ( Pr ). The higher riority of the UE, the more badwidth it has bee allocated to it. I the case if secod UE with Guarateed Bit Rate ad first, third, ad fourth UEs with No Guarateed Bit Rate, the the order of s allocatio will be chaged (Table III). Procedure of badwidth allocatio for each UE is followig:.5 Mbs, 3. Mbs, 0.8 Mbs, ad Mbs. 73
Lemeshko OV et al., Sch. J. Eg. Tech., Aril 06; 4(4):69-74 Table 3: Procedure of Resource Blocks Allocatio to UEs (Oly Secod UE with GBR) 0 3 4 5 6 7 G 0 3 Subset 0 3 Subset 4 8 9 0 3 4 G 4 5 6 7 Subset 0 Subset As show i Table III, LTE dowlik resource has bee allocated amog the four UEs accordig to their requiremets for bit rate ( R req ), resource tye (GBR/No GBR) ad riority level ( Pr ). That is why to secod UE for which is Guarateed Bit Rate (GBR) ad R req 3 Mbs allocated badwidth is 3. Mbs. The rest of the statios for which are No Guarateed Bit Rate (No GBR) badwidth allocated accordig to their riorities, i.e. to first UE havig the highest riority allocated.5 Mbs, ad to fourth, which has the lowest riority 7, allocated just Mbs. CONCLUSION I this work roosed riority based balacig model of resource allocatio i LTE dowlik suortig RAT, which is a further develomet of the aroach roosed i [6-8]. The ovelty of model is that it ca be used to describe the rocess of s allocatio i LTE dowlik give UEs requests riority. Usig the model allows to otimize the rocess of resource allocatio i LTE dowlik i solvig the roblem by mixed-iteger liear rogrammig, because some variables of (3) are Boolea, balacig variable (8) is a ositive real variable, ad objective fuctio (9) ad costraits (4)-(8) are liear. The advatage of the model is that the balacig of resource blocks umber allocated to each of UEs is erformed based o QoS requiremets: demaded bit rate, riority ad resource tye (with or without guaratee). Preseted results cofirmed the efficiecy of model ad adequacy of obtaied o its basis solutios. This model ca be used as the base of e-node LTE software i solvig roblems resource allocatio i LTE dowlik with use RAT. Develomet of this aroach is see i the use of dyamic models of resource allocatio rereseted i the state sace. This will allow more fully take ito accout ot oly the curret state of the LTE etwork, but also the dyamics of its chage over time, due to variatios i the sigal-oise ratio, locatio ad umber of UEs, ad requiremets to QoS level. REFERENCES. 3GPP TS 36. V3.0.0 (05-); 3rd Geeratio Partershi Project; Techical Secificatio Grou Radio Access Network; Evolved Uiversal Terrestrial Radio Access (E-UTRA); Physical chaels ad modulatio (Release 3). Valboe, Frace, 05.. 3GPP TS 3.03 V3.6.0 (05-); 3rd Geeratio Partershi Project; Techical Secificatio Grou Services ad System Asects; Policy ad chargig cotrol architecture (Release 3). Valboe, Frace, 05. 3. Ghosh A, Zhag J, Muhamed R, Adrews JCr; Fudametals of LTE. Pretice Hall, USA, 00: 4-50. 4. Iosif O, Baica I; O the Aalysis of Packet Schedulig i Dowlik 3GPP LTE System. The Fourth Iteratioal Coferece o Commuicatio Theory, Reliability, ad Quality of Service (CTRQ 0), Budaest: IARIA, 0; 99-0. 5. Kawser MT, Farid HMAB, Hasi AR, Sadik AMJ, Razu IК; Performace Comariso betwee Roud Robi ad Proortioal Fair Schedulig Methods for LTE. Iteratioal Joural of Iformatio ad Electroics Egieerig, 0; (5): 678-68. 6. Garkusha S, Al-Dulaimi AMK, Al-Jaabi HDK; Result of Develomet of Model for Badwidth Maagemet i LTE Dowlik with Resourse Allocatio Tye. XIIIth Iteratioal coferece, the exeriece of desigig ad CAD system (CADSM 05), February 05; 409-43. 7. Garkusha S, Al-Dulaimi AMK, Al-Jaabi HD; Model of Resource Allocatio Tye for LTE Dowlik. IX Iteratioal Coferece o Atea Theory ad Techiques (ICATT), Aril 05; 79-8. 8. Al-Dulaimi AMK; Liear Model of Badwidth Allocatio i LTE Dowload with RAT. Secod Iteratioal IEEE Coferece Problems of Ifocommuicatios. Sciece ad Techology, Proceedigs of PICS&T-05, Ukraie, October 05; 8-85. 74