Edge-position modulation for high-speed wireless infrared communications

Recent developments in indoor optical wireless systems

“…This is defined as the ratio of the achievable bit-rate (R bit ) to the bandwidth (B) of the transceiver, providing a measure of the utilisation of the bandwidth of the transceiver by a modulation technique, thus [7] η B = R bit B…”

“…The power efficiency (η P ) of a modulation scheme is given by the average optical power required to achieve a given BER at a given data rate [6]. Mathematically, η P is defined as the ratio of energy per optical pulse to the mean energy required per bit, E b , for a normalised transmit pulse shape, p(t), [7] given by…”

“…The relationship between the power efficiency and bandwidth efficiency is [7] η P = η B DC (5) where DC is the average duty cycle of the modulated signal, given by the average ratio of the high pulse duration to the low pulse duration during the transmission of a long data packet.…”

“…The EPM technique divides the transmission time interval into discrete slots, each of which is slightly greater than the rise time interval plus the jitter interval of the rising edge of the transmitted pulses [7]. Since the rise time and jitter interval are much smaller than the pulse length, the time slots for EPM can be smaller than the time slots for PPM.…”

“…A detailed channel model for a Line-of-Sight (LOS) link is presented in [7] and is depicted in Fig. 1b.…”