User Grouping for Hybrid VLC/RF Networks With NOMA: A Coalitional Game Approach

Abstract

Recently, visible light communication (VLC) networks have emerged as a promising alternative for indoor data access, due to high data rate, low implementation cost, and immunity to radio frequency (RF) interference. However, the co-existence of VLC with the RF access points as well as the dependence of VLC to room illumination compel both technologies to work in parallel and thus, to form a hybrid heterogeneous VLC/RF network. This network offers the advantages of both technologies, namely increased capacity and ubiquitous coverage. Furthermore, non-orthogonal multiple access (NOMA) is a very promising candidate technique for the next generation of wireless networks, mainly due to its increased spectrum efficiency compared to orthogonal access schemes. However, the optimal user grouping in NOMA is a combinatorial NP-complete problem, which calls for low complexity techniques. To this end, in this paper, we propose the use of coalitional game theory, where the users served by the same access point (VLC or RF) form a single coalition, while the users can switch through coalitions based on their payoff. A novel utility function is proposed that takes into account the peculiarities of the NOMA hybrid VLC/RF network. Finally, a coalition formation algorithm is presented as well as an efficient power allocation policy. Computer simulations validate the presented analysis and reveal the effectiveness of the proposed user grouping scheme compared to an opportunistic approach.INDEX TERMS Coalitional game theory, heterogeneous network, non-orthogonal multiple access (NOMA), user grouping, visible light communications (VLC).

Resource Allocation for Hybrid Visible Light Communications (VLC)-WiFi Networks

“…The requested rate of randomly generated users in the interval [1,3], unit: Mpbs; 6) In the interval [10,50], the distance between user location and AP is randomly generated, the order of magnitude is 10, and the unit is m. The the simulation results of the two bandwidth allocation distribution algorithms is shown in Fig. 6 and Fig.…”

“…3) The number of initial users in the area a is 5 in a single WiFi area, 10 in area B, and 10 in VLC; 4) The signal-to-noise ratio of the transmitted signal is 10dB; 5) At the end of each scheduling cycle, the change range of the number of people in the two networks is [-5,5]; 6) The rate of randomly generated user requests in the interval [1,3], in Mbps; 7) In the interval [10,50], it generates the distance between WiFi user and AP randomly in area a, the unit is m, and the order of magnitude is 10. The distance between WiFi user location and WiFi hotspot in area B is 20m, and the distance between VLC user location and VLC hotspot is 10m; 8) The simulation assumes that the threshold of decisionmaking between the two systems after information interaction is the average user rate and whether it reaches 60% of the system resources.…”

“…Paper [28][29][30][31][32][33][34][35][36] studied various characters. In [28], the RR algorithm makes the terminals have the same fairness, at the expense of the performance, such as throughput.…”

“…Considering the demand for quantity and quality, the network is developing towards high performance, high quality, high speed, and high throughput. VLC has emerged as a promising alternative for next-generation wireless networks (5G and beyond), due to its high data rate, flexible coverage, and free from radio frequency (RF) interference [1][2][3]. VLC uses light-emitting diodes (LEDs) to transmit data by modulating the intensity of visible light and can be used as complimentary wireless access technology to WiFi and cellular systems [4][5].…”

Rate-Splitting Multiple Access: Unifying NOMA and SDMA in MISO VLC Channels

“…Nevertheless, the enhancement of NOMA performance through reducing channels symmetry need to be further explored in the context of VLC. Finally, it is noted that NOMA-based hybrid VLC/RF systems have been proposed as acceptable solutions that are capable of compensating for the limitation of VLC systems, particularly in uplink communication scenarios [87]- [89]. In the same context, hybrid wavelength division multiplexing (WDM)-NOMA has been proposed in [90], where multi-color LEDs are used to allow simultaneous transmissions at different wavelengths.…”