An improved spectral efficiency based channel estimation algorithm and its low power vlsi architecture for mimotftofdm systems

Abstract

Multicarrier and Multiuser modulation techniques are required for transferring the multimedia information at a high speed to the remote unit. Hence, Orthogonal Frequency Division Multiplexing (OFDM) technique is adopted due to its high spectral efficiency for high speed data transmission and reception in wireless communication system. This also have the high mitigating property against Inter Symbol Interference (ISI). Determination of Channel State Information (CSI) is important for error free data transmission and reception. The receiver has CSI module which determines the state of the channel in wireless communication system. At present, Least Square (LS) channel estimation (which determines the least value of error rate in received symbols) and Minimum Mean Square Error (MMSE) estimation (which determines the least mean value of error rate in received symbols) are used as channel estimators to estimate the state or condition of the wireless channel. The main limitations of these conventional channel estimators are that they failed to suppress the noise level in receiver side and also required previous state which increased the latency of the decoding process. Most conventional wireless communication system prefers LS channel estimation technique. This has less complexity, but the error rate is high. In this research work, Time Frequency Training Orthogonal Frequency Division Multiplexing (OFDM) can be easily extended to Multiple Input and Output (MIMO) system. The transmission frame scheme is composed of one preamble and subsequent Time Frequency Training (TFT) OFDM sub frames for MIMO system. Time-frequency joint channel estimation method is accurately track the channel variation. The received timedomain Training Sequence is used for path delay estimation while the frequency domain pilots are used for path gains acquisition under the compressive sensing based ISMA (Improved Sparsity Measurement Algorithm) estimation Algorithm. newline