International Journal of Computer Networks & Communications (IJCNC) Vol.4, No.4, July 2012 DOI : 10.5121/ijcnc.2012.4419 291           Rajendrasingh Annauth 1 and Harry C.S.Rughooputh 2 1 Department of Electrical and Electronic Engineering, University of Mauritius, Reduit, Mauritius rannauth@mail.gov.mu 2 Department of Electrical and Electronic Engineering, University of Mauritius, Reduit, Mauritius r.rughooputh@uom.ac.mu Abstract Orthogonal Frequency Division Multiplexing (OFDM) has the inherent properties of being robust to interference and frequency selective fading and is de facto the adopted multiplexing techniques for the 4 th generation wireless network systems. In wireless system, resources such as bandwidth and power are limited, intelligent allocation of these resources to users are crucial for delivering the best possible quality of services. In this paper the problem of resource allocation in multiuser OFDM system is tackled using multi objective particle swarm optimization. Simulation results are presented for 3GPP-LTE system. KERWORDS Multi-Objective Particle Swarm Optimization, OFDM, Resource Allocation. 1. INTRODUCTION OFDM is a combination of modulation and multiplexing. As modulation scheme, it is suitable to handle harsh and adverse environmental condition, whereas as multiple access scheme it offers high spectral efficiency and diversity. Applications include wireless multimedia and Internet access and it stands as a potential candidate for next generation wireless communication systems. Multiuser OFDM system has the inherent advantages of being flexible in subcarriers allocation, adaptive to channel condition, provision of high spectral efficiency, lower receiver complexity and simpler implementation by inverse fast Fourier transform (FFT) and FFT. In addition, OFDM has the merits of mitigating the effect of frequency selective fading and inter symbol interference, inherent in high data rate transmission, by converting frequency selective channel into a number of parallel narrowband flat fading sub-channels A major problem in multiuser OFDM system is rate and power allocation to subcarriers. Two classes of resource allocation exist – the Fixed Resource Allocation (FRA) and Dynamic Resource Allocation (DRA). Assignment in FRA schemes is non optimal, since scheme is fixed regardless of channel conditions. On the other hand, DRA schemes are based on users channel gains and make full use of multiuser diversity to achieve higher performance. In dynamic multiuser literature, two classes of optimisation techniques have been proposed, specifically Margin Adaptive objective to minimize the overall transmit power under data constraint, and Rate Adaptive objective maximization of the data rate under power constraint. These optimization problems are nonlinear and computationally intensive to solve as complexity increases exponentially with constraints and variables [1]. The solution space of OFDM allocation problem is too large and conventional algorithms cannot solve it effectively.