However, the pilot positions optimization schemes (i.e., algorithms for determining the optimal pilot placements) are not effective for NC-OFDM systems.
Therefore, we propose Grey Wolf Optimizer (GWO) for pilot tones optimization to enhance the performance of Least Squares (LS) algorithm employed for channel estimation in Orthogonal Frequency Division Multiplexing Interleave Division Multiple Accessss (OFDM IDMA) system.
For instance, a number of studies have been presented based on the optimal pilot design and the optimization criteria of interest for channel estimation in MIMO-OFDM systems [12-14] [12-14]
By employing equal powered pilot symbols, the optimization problem in [7, 8] is simplified.
Therefore, pilot design requires optimization for the amount of pilot symbols, the locations of these symbols in the data stream, and the power allocated for them.
Since the channel estimation performance is affected directly by the positions of pilot tones, the optimization of pilot placement process known as having quite important role on minimizing the estimation errors has become a significant task for the multicarrier transmission technologies.
Twenty-four native Dutch speakers (10 males and 14 females, 18 28 years of age) participated in the study; four of them were selected as a pilot group (see "Optimization of the analysis").
The design of optimal pilot symbol calls for joint optimization of the pilot placement K p and power distribution λ.
Moreover, increasing the accuracy and bandwidth efficiency of channel estimation could be guaranteed using optimal pilot allocation based on RIP optimization.
From the simulation results, we can see that optimized pilot tones derived by particle swarm optimization outperforms the orthogonal and random pilot tones significantly in terms of MSE and BER.
