Abstract
Index modulation (IM) has been attracting considerable research efforts in recent years as it is considered a promising technology that can enhance spectral and energy efficiency and help cope with the rising demand of mobile traffic in future wireless networks. In this paper, we propose a cloud radio access network (C-RAN) suitable for fifth-generation (5G) and beyond systems, where the base stations (BSs) and access points (APs) transmit multidimensional IM symbols, which we refer to as precoding-aided transmitter-side generalized space–frequency IM (PT-GSFIM). The adopted PT-GSFIM approach is an alternative multiuser multiple-input multiple-output (MU-MIMO) scheme that avoids multiuser interference (MUI) while exploiting the inherent diversity in frequency-selective channels. To validate the potential gains of the proposed PT-GSFIM-based C-RAN, a thorough system-level assessment is presented for three different three-dimensional scenarios taken from standardized 5G New Radio (5G NR), using two different numerologies and frequency ranges. Throughput performance results indicate that the 28 GHz band in spite of its higher bandwidth and higher achieved throughput presents lower spectral efficiency (SE). The 3.5 GHz band having lower bandwidth and lower achieved throughput attains higher SE. Overall, the results indicate that a C-RAN based on the proposed PT-GSFIM scheme clearly outperforms both generalized spatial modulation (GSM) and conventional MU-MIMO, exploiting its additional inherent frequency diversity.
Highlights
Introduction published maps and institutional affilAs technology advances in wireless communications, more innovative solutions have been appearing
Current fifth-generation (5G) technology is capable, efficient and flexible, but can be improved further. 5G technology works in bands below 7 GHz, which corresponds to the Frequency Range 1 (FR1) of 5G New Radio (5G NR) [1], and above 24 GHz, corresponding to Frequency Range 2 (FR2) of 5G NR, and can accommodate many more users than the last generation counterpart
We present numerical simulations, both link- and system-level, for the PT-GSFIM-based downlink scheme integrated into a 5G NR system
Summary
We consider the downlink of an OFDM-based MU-MIMO system, where a BS equipped with Ntx antennas transmits to Nu users. If we have a scenario with Nf = 8 and Naf = 6, only six out of each group of eight subcarriers are selected, and only the selected ones are activated to convey modulated symbols through their respective indices. This pattern of activation of subcarriers is combined with the pattern of activation of the spatial domain which means that not all antennas will be transmitting in an active subcarrier. Denoting Ns as the total number of streams assigned to the antennas on each subcarrier, only Na of the position will contain modulated symbols which will correspond to active antennas
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