A Wireless Optical Backhaul Solution for Optical Attocell Networks

Abstract

The problem of backhauling for optical attocell networks has been approached by a number of wired solutions such as in-building power line communication (PLC), Ethernet and optical fiber. In this paper, an alternative solution is proposed based on wireless optical communication in visible light and infrared (IR) bands. A thorough analysis of signalto-interference-plus-noise (SINR) is elaborated for a multiuser optical attocell network based on direct current biased optical orthogonal frequency division multiplexing (DCO-OFDM) and decode-and-forward (DF) relaying, taking into account the effects of inter-backhaul and backhaul-to-access interferences. Inspired by concepts developed for radio frequency (RF) cellular networks, full-reuse visible light (FR-VL) and in-band visible light (IB-VL) bandwidth allocation policies are proposed to realize backhauling in the visible light band. The transmission power is opportunistically minimized to enhance the backhaul power efficiency. For a two-tier FR-VL network, there is a technological challenge due to the limited capacity of the bottleneck backhaul link. The IR band is employed to add an extra degree of freedom for the backhaul capacity. For the IR backhaul system, a power-bandwidth tradeoff formulation is presented. Closed form analytical expressions are derived for the corresponding power control coefficients. Finally, the network sum rate performance is studied using extensive Monte Carlo simulations. Index Terms-Light-fidelity (LiFi), optical attocell network, visible light communication (VLC), infrared (IR) communication, wireless backhaul, power control, multi-hop relaying, decodeand-forward (DF), direct current biased optical orthogonal frequency division multiplexing (DCO-OFDM). Received signal for the backhaul link of BS i on subcarrier k v b i,k Received noise for the backhaul link of BS i on subcarrier k γ b i Received SINR per subcarrier for the backhaul link of BS i R b i Overall achievable rate for the backhaul link of BS i Ba Bandwidth of the access system x a i,k Transmitted signal in the access link of BS i on subcarrier k y u,k Received signal for the uth UE on subcarrier k v a u,k Received noise for the uth UE on subcarrier k γu Received SINR per subcarrier for the uth UE Ra i Overall achievable rate for the access link of BS i R i Multiuser sum rate for the end-to-end downlink of BS i

Lights and Shadows: A Comprehensive Survey on Cooperative and Precoding Schemes to Overcome LOS Blockage and Interference in Indoor VLC

“…The implementation of VLC or LiFi systems may be complicated when we must connect multiple light fixtures, provided with communication capabilities, by using a wired backhaul. To this end, the first work that studies the feasibility of a wireless backhaul in LiFi systems corresponds to [ 92 ], where each AP needs 6 extra LEDs in addition to several PDs for receiving data from neighbouring APs. Later on, new studies such as [ 45 ] propose a practical yet sophisticated wireless backhaul link based on VLC reflections.…”

“…Notice that this fact makes the network system based on precoding schemes more resilient to the blockage of one or several links between any pair optical AP user, as discussed below. As described in the previous section, multiple approaches can be considered for providing backhauling in VLC, such as PLC [ 83 , 84 ], Ethernet [ 86 ], optical fiber [ 87 ] and wireless, either optical or RF communications [ 45 , 90 , 91 , 92 ]. Thus, precoding schemes require one to implement a central unit (CU) to generate the symbols intended to the users, manage the pilot transmission, obtain the CSI knowledge and calculate the precoding vectors, as can be seen in Figure 10 .…”

Analysis of the Impact of Misaligned Wireless Backhaul Links on Optical Attocell Networks

“…The cost for installation and maintenance could be extremely high. Wireless backhaul solutions based on VLC links are proposed in [1], [2]. VLC backhaul links are viable solutions for optical attocell networks which have used VLC for access data transmission.…”

A Cross-Layer Heuristic Algorithm for Addressing Shadowing Problem in Optical Attocell Networks

“…u∈U loads along each route to u = requested rate of u (2) Visible light communication (VLC) has been drawing scientific interests as complement to radio-frequency (RF) wireless technologies. VLC using light-emitting-diodes (LEDs) as transmitters can support simultaneous illumination and wireless access data transmission to user equipment (UE) such as smartphones and laptops.…”

“…Wireless backhaul technologies using line-ofsight (LOS) and mirror-aided non-LOS link configurations as shown in Fig. 1(b) can be easily installed and configured without changing the existing power grid [1], [2]. Both wireless link configurations require auxiliary transceivers.…”