An inter-lighting interference cancellation scheme for MISO-VLC systems

Capacity enhancement of an indoor visible light communication system using cooperative transmission

“…On the receiver side, the total received optical power P R is the combination of the received optical power from the desired and interfering LEDs that lie within the PD's FOV and is given in [13,16,18] as…”

“…This ensures the existence of the communication link between the transmitter and the receiver because each LED transmits the composite data. The proposed scheme is based on a combination of cooperative transmission and ILIC [18]. The cooperative transmission is applied in the transmitter side to coordinate the data transmission in which each cooperative LED forwards the composite data obtained by the weighted sum of different data to increase the capacity.…”

“…it is impossible to recover the data when the signals are received with approximately equal power [12]. Several authors have proposed techniques to mitigate CCI, such as inter-lighting interference cancellation (ILIC) [18] and enhanced-ILIC [19], and to avoid CCI by using frequency planning [17] and coordinating the data transmission among the LEDs [1,6,14,20], which can cooperate to transmit common data that can be encoded when transmit diversity is employed [5,15,21]. Since cooperative transmission and ILIC are performed in the transmitter and the receiver, respectively, as described below, they can work together to improve the performance of an indoor VLC system while sharing frequency resources.…”

“…Besides enhancing the transmission capacity of MISO-VLC systems due to the LEDs transmitting different signals, the ILIC scheme improves the average bit error rate (BER) performance when the signals are received with different power [18] because it can detect the low received power signal after reducing CCI. When the LEDs transmit with the same power, the receiver power depends on the PD position as a consequence of the channel DC gain changing, so the signal of the near LED is received with high power while the signal of the far LED is received with low power.…”

“…It is based on the power difference of the received signals because it mainly consists of detecting the high received power signal and eliminating it from the received signal that was stored and then detecting the low received power signal, which is severely interfered with by the other signal. According to [18], ILIC achieves the lowest average BER performance when the received power ratio is two and it cannot recover the data when the signals are received with equal power because CCI is at a maximum. In [19], the ILIC scheme is enhanced by applying power allocation at the transmitter side, whose power weights are selected to combat the equal received power and obtain two signals with different received power whose ratio complies with the threshold found in ILIC.…”