This paper emphasizes a method for improving spectral efficiency based on small cells (SCs) deployed in an existing macrocell (MC), which ultimately results in overall enhancement of the network capacity and coverage area. In addition, it allows an unlicensed secondary network to deliver messages through opportunistic access to the licensed network spectrum. By deploying SCs, users either inside or outside high residential buildings and/or commercial buildings can acquire signals during communications without interruption. The connectivity in the alliance of the two-tier networks becomes abundant, resulting in spectral efﬁciency improvement. In this paper, we ﬁrst recall performance based on the Vandermonde-subspace frequency division multiplexing (VFDM) spectrum-sharing technique for spectrum management under both conventional (single-user) and enhanced scenarios; subsequently, the proposed method is introduced for comparison purposes. The performance of both methods is manifested in simulation results for the achievable rate, which demonstrate that the proposed approach outperforms enhanced VFDM and is a potential candidate in next-generation cellular technology. The motivation for the preference for SC deployment in the proposed approach is due to worthy characteristics (low power, low cost, very light weight, and self-organization). Unlike MCs, which need a considerable budget, they are installed anywhere without a lot of expense, and hence, save the network infrastructure.
Available online: http://www.ieiespc.org/include/pdfdownload.asp?filename=IEEKSPC_2019_8_2_20190430135157_1.pdf