Capacity Bounds for the Gaussian IM-DD Optical Multiple-Access Channel

Abstract

Abstract-Optical wireless communications (OWC) is a promising technology for closing the mismatch between the growing number of connected devices and the limited wireless network capabilities. Similar to downlink, uplink can also benefit from OWC for establishing connectivity between such devices and an optical access point. In this context, the incoherent intensitymodulation and direct-detection (IM-DD) scheme is desirable in practice. Hence, it is important to understand the fundamental limits of communication rates over an OWC uplink employing IM-DD, i.e., the channel capacity. This uplink, modeled as a Gaussian multiple-access channel (MAC) for indoors OWC, is studied in this paper, under the IM-DD constraints which form the main difference with the standard Gaussian MAC commonly studied in the radio-frequency context. Capacity region outer and inner bounds for this channel are derived. The bounds are fairly close at high signal-to-noise ratio (SNR), where a truncatedGaussian input distribution achieves the capacity region within a constant gap. Furthermore, the bounds coincide at low SNR showing the optimality of on-off keying combined with successive cancellation decoding in this regime. At moderate SNR, an optimized uniformly-spaced discrete input distribution achieves fairly good performance.

Low-SNR Asymptotic Capacity of MIMO Optical Intensity Channels with Peak and Average Constraints

“…Additionally, Fig. 2b shows R orm σ (A, p) given in (14), which is the achievable rate using OOK, spatial repetition, and MRC. This plot verifies Corollary 1.…”

“…Proof: The statement follows using Theorem 1, applying results in [28] to (14), and using the definition of C [2] σ,0 (A, E) given in Sec. II.…”

“…On the other hand, using OOK, spatial repetition, and MRC achieves the rate R orm σ A, E M A as defined in (14). Using [28,Theorem 1] this can be written as…”

“…The SISO IM-DD channel with input-dependent (relative intensity) Gaussian noise has been studied in [5]. The capacity of multi-user SISO IM-DD channels has been studied in [13], [14]. The performance of transmission schemes in IM-DD OWC in terms of error and outage probability has been investigated in [15]- [19], to name a few.…”

An achievable rate region and a capacity outer bound for 3‐user Gaussian multiple access channel with feedback

“…Furthermore in Ardestanizadeh et al, 28 a class of generalized linear feedback codes has been investigated where the feedback signals are incorporated linearly into the transmit signals, and a maximum sum rate for N-user MAC was achieved by this generalized linear feedback codes under symmetric users power constraints. Uplink communication or video streaming in cellular networks, ad hoc networks or device to device (D2D) communication, are some applications that can be modeled as MAC (previous studies [29][30][31][32][33][34].…”