An Energy-Efficient Optical Wireless OFDMA Scheme for Medical Body-Area Networks

Abstract

The transfer of health monitoring data from multiple patients using wireless body-area networks requires the use of robust, and energy and bandwidth efficient multipleaccess schemes. This paper considers the frequency-division multiple access for the wireless uplink to a fixed access point when using infrared signals to collect medical data from several patients inside an emergency waiting room. The conventional optical orthogonal scheme applies Hermitian symmetry to obtain real-valued signals, which implies increased computational complexity. We consider a new approach transmitting only the real part of a complex-valued signal, where no such constraint is imposed. Based on the proposed scheme, and taking into account the limited dynamic range of an infrared light-emitting diode, we study the performance of direct current biased and asymmetrically clipped schemes, and show their advantage in terms of energy efficiency and computational complexity, as compared with the conventional schemes. For instance, we show that by using asymmetric clipping, around 35 mW less transmit power is needed to achieve a bit error rate of 10 -3 in the considered scenario. We also demonstrate the robustness of the proposed scheme against multiple access interference.

On the Performance of SPAD-Based Optical Wireless Communication With ACO-OFDM

“…Note that in this work the lower limit of the light source dynamic range is assumed to be zero which leads to the additional DC biasing unnecessary [6]. However, the biasing of x t [n] is required for cases with non-zero lower limit [9].…”

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

“…One major issue of O-OFDMA is the relatively high peakto-average power ratio (PAPR), resulting in further clipping (modelled as so-called "clipping noise") the signal in order to limit the signal peaks in the LED dynamic range (DR). Moreover, clipping the TD signal limits the power consumption of power amplifiers, but at the cost of performance degradation [23]. The reduction of clipping noise so far has relied on techniques, such as block coding, selective mapping, and pilotassisted transmission [24,25].…”

“…The reduction of clipping noise so far has relied on techniques, such as block coding, selective mapping, and pilotassisted transmission [24,25]. However, as shown in [23], for relatively low modulation order, clipping noise has a marginal degrading effect.…”

A Secure Optical Body Area Network Based on Free Space Optics and Time-Delayed 2D-Spectral/Spatial Optical CDMA

“…OBAN is a relatively recent research field; therefore, abundant published work is not yet available. Works related to OBAN published over the past decade include [2,4,6,8,[10][11][12][13][14][15][16][17]. Mirza et al proposed secure OBAN architectures based on spectral amplitude coding-OCDMA (SAC-OCDMA) [2] and optical chaos [8].…”

“…Chevalier et al proposed channel modelling for a diffused optical channel between on-body sensors [14] and a star OBAN topology based on a diffused optical channel and spreading codes [15]. Hasan et al proposed uplink transmission between medical sensors and a coordinator based on OCDMA [16] and OFDMA [17]. It is evident from the above discussion that most of the works published to date discuss channel modelling, patient mobility, and multiple access schemes.…”