Performance Analysis of Adaptive Multi User OFDM
نویسنده
چکیده
The demand for high-speed mobile wireless communications is rapidly growing. OFDM technology promises to be a key technique for achieving the high data capacity and spectral efficiency requirements for wireless communication systems of the near future. In our proposed method Adaptive modulation techniques is used for maximizing the data throughput of subcarriers allocated to a user. It measures the SNR of each subcarrier in the transmission, then selecting a modulation scheme that will maximize the spectral efficiency, while maintaining an acceptable BER. This technique has been used in Asymmetric Digital Subscriber Line (ADSL) to maximize the system throughput.In addition Adaptive user allocation improves signal power of 3-5 dB. Also in the first techniques Crest Factor (CF)is reduced by using OFDM pilot symbols ,in the second techniques reduces the CF of data carrying symbols, by including additional subcarriers
منابع مشابه
Cross-layer Packet-dependant OFDM Scheduling Based on Proportional Fairness
This paper assumes each user has more than one queue, derives a new packet-dependant proportional fairness power allocation pattern based on the sum of weight capacity and the packet’s priority in users’ queues, and proposes 4 new cross-layer packet-dependant OFDM scheduling schemes based on proportional fairness for heterogeneous classes of traffic. Scenario 1, scenario 2 and scenario 3 lead r...
متن کاملMulti-user Adaptive OFDM System for Multi-rate Services in Wireless Communications
This paper analyzes performance and throughput of an adaptive bit allocation and variable rate algorithm depending on channel state information (CSI) and a transmit power in a multi-user OFDM transmission. The purpose of the presented multi-rate OFDM system using adaptive modulation is to increase bandwidth efficiency by controlling constellation size and to adapt proper service for each user a...
متن کاملEmpirical Mode Decomposition based Adaptive Filtering for Orthogonal Frequency Division Multiplexing Channel Estimation
This paper presents an empirical mode decomposition (EMD) based adaptive filter (AF) for channel estimation in OFDM system. In this method, length of channel impulse response (CIR) is first approximated using Akaike information criterion (AIC). Then, CIR is estimated using adaptive filter with EMD decomposed IMF of the received OFDM symbol. The correlation and kurtosis measures are used to sel...
متن کاملMulti-User Adaptive Resource Allocation Scheme for WLAN OFDM-MIMO Transmission
. Orthogonal Frequency division multiplexing (OFDM) has recently been proposed for use in high data-rate wireless systems. OFDM has an important property of spectrum utilization technique that distributes each tone, which is orthogonal with every other tone. The system capacity can be significantly improved by multiple transmit and receive antennas that are used to form Multi-input multi-output...
متن کاملPerformance Comparison of Wavelet and FFT Based Multiuser MIMO OFDM over Wireless Rayleigh Fading Channel
This article examines the performance of Wavelet based Multi-User MIMO OFDM (MUMIMO WOFDM) systems and a comparison is made with classical FFT based multiuser MIMO OFDM system. Wavelet analysis has some strong advantages over fourier analysis, as it allows a time-frequency domain operation, allowing optimal resolution and flexibility. Wavelets have been satisfactorily applied in almost all the ...
متن کامل