Visible light communication (VLC) is envisioned as a core component of future wireless communication networks due to, among others, the huge unlicensed bandwidth it offers and the fact that it does not cause any interference to existing radio frequency (RF) communication systems. Most research on RF and VLC coexistence has focused on hybrid designs where data transmission to any user could originate from either an RF or a VLC access point (AP). However, hybrid RF/VLC systems fail to exploit the distinct transmission characteristics of RF and VLC systems to fully reap the benefits they can offer. Aggregated RF/VLC systems, in which any user can be served simultaneously by both RF and VLC APs, have recently emerged as a more promising and robust design for the coexistence of RF and VLC systems. To this end, this paper, for the first time, investigates AP assignment, subchannel allocation (SA), and transmit power allocation (PA) to optimize the energy efficiency (EE) of aggregated RF/VLC systems while considering the effects of interference and VLC line-of-sight link blockages. A novel and challenging EE optimization problem is formulated for which an efficient joint solution based on alternating optimization is developed. More particularly, an energy-efficient AP assignment algorithm based on matching theory is proposed. Then, a low-complexity SA scheme that allocates subchannels to users based on their channel conditions is developed. Finally, an effective PA algorithm is presented by utilizing the quadratic transform approach and a multi-objective optimization framework. Extensive simulation results reveal that: 1) the proposed joint AP assignment, SA, and PA solution obtains significant EE, sum-rate, and outage performance gains with low complexity, and 2) the aggregated RF/VLC system provides considerable performance improvement compared to hybrid RF/VLC systems.
翻译:可见光光通信(VLC)被设想为未来无线通信网络的核心组成部分,其原因除其他外包括:它所提供的无证带宽巨大,而且它不会对现有无线电频率通信系统造成任何干扰;大多数关于RF和VLC共存的研究侧重于混合设计,向任何用户传输的数据可能来自RF或VLC接入点(AP);然而,混合的RF/VLC系统未能利用RF和VLC系统独特的传输特点,以充分获得它们所能带来的好处。 综合的RF/VLC系统,其中任何用户都可以同时使用RF和VLCAP系统,其中任何一个用户都可以同时使用RF和VLC AP系统;最近,关于RF和VLC共存的大多数研究侧重于混合设计;为此,本文首次调查AP的派任任、次通道分配(SA),并传输电力分配(PA),以优化RF/VLC系统组合的低能效(E)系统,同时考虑到拟议的干涉和VLC线链接系统的影响。