Statistical based optimization of number of pilot signals in LTE/LTE-A for higher capacity

LTE/LTE-A systems use pilot or reference signals for channel estimation occupying a significant part of the time-frequency grid. In this paper the efficiency of channel equalization over a flat-fading channel is analysed taking into account the estimation error. Closed form formulas are provided to calculate symbol-to-error ratio depending on the estimation error using QPSK modulation. Then, a trade-off is proposed based on the statistical behaviour of estimation error to maximize the effective channel capacity by tuning the number of pilot signals on subcarrier level. Higher amount of reference signals improves the channel equalization, but occupies unnecessary resource slots reducing the effective channel capacity. Numerical results confirm that choosing the appropriate number of reference symbols is able to maximize the effective channel capacity. Furthermore, the results are compared to the LTE/LTE-A standard and it is found that the effective channel capacity is better in every investigated scenario.