Resource Allocation Algorithm with Dynamic Subcarrier Assignment in OFDMA-based Wireless Networks

Abstract

Original scientific paperThe allocation of available resources is one of the main issues in multi-user systems. Dependence of system capacity on radio link quality is an additional obstacle of efficient resource allocation in wireless networks. Combinations of two opposite approaches -fair resource allocation and system capacity maximization are used to solve this problem in practice.This paper proposes a resource allocation method that is primarily based on assigning almost an equal bandwidth to all users. System capacity maximization is achieved by selecting the subcarriers with the best SNR values. This algorithm was developed for orthogonal frequency division multiple access (OFDMA) wireless systems. Resource allocation is done at the subcarrier level according to the weight factor that had been calculated for each user. Frequency hopping was used to increase frequency diversity and to make the system more robust to disturbance. Frequency hopping pattern is determined dynamically on the basis of SNR value of each subcarrier.The results of the proposed algorithm are compared with the water filling (WF) and proportional fairness (PF) methods. The influence of various data traffic classes on system throughput and resource allocation is also described.Key words: OFDMA, QoS, Resource allocation, Subcarrier scheduling Algoritam alokacije resursa s dinamičkim pridruživanjem podnosioca u bežičnim mrežama zasnovanim na OFDMA-u. U sustavima s više korisnika jedno od glavnih pitanja je kako podijeliti raspoložive resurse. Kod radio mreža dodatni otežavajući faktor predstavlja promjenjivost kapaciteta sustava ovisno o kvaliteti radio veze. U praksi se za raspodjelu resursa obično koriste algoritmi koji su kombinacija dvaju oprečnih pristupa, fer raspodjele resursa i maksimizacije kapaciteta sustava.U ovom radu predložena je metoda primarno bazirana na fer raspodjeli resursa. Maksimizacija kapaciteta sustava ostvarena je odabirom podnosilaca s najboljim mogućim SNR-om. Algoritam je razvijen za sustave bazirane na OFDMA. Dodjela resursa korisnicima vrši se na razini pojedinog podnosioca prema izračunatom težinskom faktoru za svakog korisnika posebno. Kako bi se povećao frekvencijski diverziti i sustav učinio otpornijim na smetnje, uvedeno je frekvencijsko skakanje prema dinamički odreenom predlošku. Predložak se formira na osnovu SNR vrijednosti odreene po svakom podnosiocu.Rezultati predloženog algoritma usporeeni su s WF (water filling) i PF (proportional fairness) algoritmima. Prikazan je utjecaj različitih klasa prometa na prijenosni kapacitet i raspodjelu resursa sustava.

Cross-layer Dynamic Subcarrier Allocation with Adaptive Service Rate Control in SC-FDMA System

“…With the rapid development of multimedia applications and high-speed data transmissions, effective radio resource allocation and management plays an increasingly crucial role in heterogeneous network [1][2]. The dynamic subcarrier allocation (DSA) scheme aiming at efficient wireless spectral resource utilization has drawn an attractive attention [3][4][5][6][7].…”