Minimizing the driving power for Non Orthogonal Multiple Access in Indoor Visible Light Communication

Abstract

Indoor Visible light Communication (VLC) systems use Light Emitting Diode (LED) luminaries for data transmission besides their main task as illumination devices. One of the challenges of VLC is minimizing the LED driving power without deteriorating the user experience.In this paper, we consider an indoor VLC network consisting of a number of LED luminaries serving a number of users. We compare the minimum LED driving power required to guarantee certain Quality of Service (QoS), represented by the minimum rate required per user, when using Non Orthogonal and Orthogonal Multiple Access ((N)OMA) techniques. We show that NOMA requires less driving power than OMA in order to satisfy the same QoS for the same number of users. Therefore, NOMA is more power efficient and gives the users more freedom to dim the light to their taste or comfort without deteriorating their QoS.We statistically characterize the NOMA minimum driving power when only the number of users and the number of LEDs are known (without knowledge of their exact locations). This is achieved by deriving the Probability Density Functions (PDF) for its upper and lower bounds. The PDF is the most comprehensive statistical characterization. It helps estimating the probability a room with a certain number of LEDs satisfies a pre-specified minimum rate for a certain number of users without causing power damage to the LEDs. It also helps estimating the average and the variance of the driving power which reflect on the illumination level.