Patent Document ID: 8588204
Application ID: 12705574
Patent Flag: 1

Claim One:
1. A superimposed training (ST) based channel estimation method involving a chirp based training sequence for equalization in uplink OFDMA systems adapted to perform free of pilot assistance and ensure improved performance and higher bandwidth efficiency, comprising an iterative time domain least squares based channel estimation involving superimposed training sequences based uplink OFDMA/SC-FDMA; using available coherence time and coherence bandwidth of the channel in a computationally efficient manner involving an estimator; bit error rate (BER) used as the criterion for the choice of optimal chirp based training sequence for ST based OFDMA; assigning data symbol associated with set of subcarriers to an user and frequency domain vectors associated with said user of a OFDMA symbol are formed and passed through-IDFT block; providing said optimal chirp based training sequence with uniform energy in all the subcarriers involving c t ⁡ ( k ) = IDFT N ⁢ { DFT N ⁡ [ ⅇ j ⁢ 2 ⁢ π ⁢ ⁢ n N ⁢ ( Q ⁡ ( t - 1 ) + n 2 + 1 ) ] × W t ⁡ ( k ) } , ⁢ n = 0 , 1 , … ⁢ ⁢ N - 1 , t = 1 , 2 , … ⁢ ⁢ N t where t signifies the user, n denote the nth element of the vector, Q is the order of the channel estimator, N is the number of the subcarriers, N t stands for number of the user and W t (k) is the user dependant mask defined as W t ⁡ ( k ) = { 1 , k ∈ { Ψ t } , t ∈ [ 1 , N t ] 0 , k ∉ { Ψ t } added the thus obtained optimal chirp based training sequence to the IDFT output for minimizing the bit error rate (BER); said sequence providing for reducing the error floor in the BER in the first stage of iterative process for achieving desired performance and bandwidth efficiency reducing the computational complexity; and reducing the data interference in the channel estimate in each iteration of the estimator involving interference canceller.