Impact of Synchronization Errors on the Performance of ACO-OFDMA Signaling for Medical Extra-WBAN Links

Abstract

This paper considers the use of infrared-based optical wireless communications for multi-user uplink wireless body-area networks. We propose the use of optical-orthogonal frequency division multiple access (O-OFDMA) signaling to manage the multiple access (MA) requirement for relatively high-rate medical applications. In particular, we consider asymmetrically clipped O-OFDMA and analyze its performance in terms of bit-errorrate and outage probability in the presence of multi-user time synchronization errors. These latter may occur due to mobility and random transmitter orientations, and will impact the link performance by inducing MA interference (MAI). We show that the effect of MAI increases with increasing the data rate. For instance, for 1 and 2 Mbps data rates, to achieve a target biterror-rate of 10 −3 , the link distance is limited to 1.9 and 1 m, respectively, compared to 2.2 and 1.8 m in the absence of MAI.

Time Multiplexed Optical-OFDMA for Uplink Transmission in LiFi-based IoT Networks

“…We assume perfect time synchronization for each mobile IoT device with the AP. Note that the error in time synchronization is a recurrent problem for OFDMA-based schemes, which is relatively low for an indoor scenario due to the limited mobility of the mobile users [31]. Also, in order to avoid MAI and so-called "near-far problems", both time and frequency synchronization is required for the RF OFDMA, typically referred as initial ranging [32].…”

Performance Analysis of Multiple Access m-CAP for Optical-Based Intra-WBAN Links

“…For instance, the authors in [10] employed a dynamic TDMA scheme to maximize the spectral efficiency of a visible light communication (VLC) downlink transmission system. Also, non-orthogonal MA (NOMA) and orthogonal FDMA (OFDMA) have been extensively studied for VLC applications [11]- [13]. In [13], the asymmetrically-clipped O-OFDMA signaling was considered for optical extra-WBAN links while accounting for synchronization errors.…”

“…Also, non-orthogonal MA (NOMA) and orthogonal FDMA (OFDMA) have been extensively studied for VLC applications [11]- [13]. In [13], the asymmetrically-clipped O-OFDMA signaling was considered for optical extra-WBAN links while accounting for synchronization errors. In [14], a MA multi-band carrierless-amplitude-and-phase modulation (m-CAP) was considered for multi-user VLC links.…”

“…For intra-WBAN links, optical CDMA is not a suitable scheme due to its high complexity and low bandwidth efficiency for relatively large numbers of users, resulting from the requirement of long orthogonal complementary codes [13]. Also, TDMA is not well suited for managing the heterogeneous traffic of WBAN links given its highly accurate synchronization requirements.…”