A new design of pilot symbol in 16 QAM channels

Pilot symbols are generally inserted as a compensation technique in wireless communication systems employing 16-quadrature amplitude modulation (16 QAM). This paper describes newly developed pilot symbol techniques in 16 QAM channels. There are two methodologies; one is where the pilot symbol is put on the in-phase (I) or quadrature-phase (Q) axis, and the other is where a signal state of a individual symbol before and after the pilot symbol is set on the line passing through the origin and the signal point of the pilot symbol. According to our investigation of peak-to-average power ratio (PAPR) for transmitted signal and bit error rate (BER) performances in a receiver, the first technique gives a margin of about 1.0 dB at a BER of 1.0×10^-6 without affecting the PAPR compared with conventional techniques. Furthermore, BER performance becomes error free when the roll-off factor is α=0.2 where in the second technique the symbol synchronization offset exists and Eb/No=∞. This suggests that our proposed technique improves both transmitter and receiver performance in narrow band wireless communication employing 16 QAM