No abstract

Data transmission through large intelligent meta-surfaces (LIMs) is one of the trending and key enabling technologies for 6G and beyond mobile and wireless communication networks. While the wireless communication emerges, the channel characteristics are highly unpredictable and uncontrollable. But, LIMs can control the phase shift of individual user signals from base station, and thus improves the performance of the wireless communication link. This paper proposes a passive beamforming technique and provides phase optimization which helps to improve the communication quality, and thus improves the reliability of the wireless link. Also, spreading is used to improve the end user’s receiver performance. The error rate and capacity of the proposed system are calculated, and compared with decode and forward (DF) relaying scheme. The performance of LIMs is analysed with two different channel estimation approaches, and for different number of reflecting elements. The simulation is performed under the existing orthogonal multiple access (OMA) scheme, and it evidently shows the superiority of the proposed intelligent signal estimation method.

A multi-stream cyclic interleaving architecture for an interleaved frequency division multiple access (IFDMA) system is proposed. The proposed scheme exploits the full benefits of maximal length sequence (m-sequence), in contrast to single data stream transmission scheme proposed in earlier works, thereby allowing simultaneous transmission of multiple data streams by each user. The cyclic spreading allows the separation of multiple data streams for each user in addition to intersymbol interference (ISI) minimization. The assignment of orthogonal subcarriers to each user compensates multiuser interference (MUI). The increase in the number of data stream transmission improves the data rate of the system. The proposed scheme employs maximal ratio combining (MRC) to maximize the instantaneous signal-to-noise ratio (SNR) of the multipath signal. The performances of the proposed interleaving scheme are compared with the minimum mean square error frequency domain equalization (MMSE-FDE)-based conventional interleaving scheme. Despite the simultaneous transmission of multiple data streams, the proposed scheme retains the performance of single data stream transmission.