Summary The next generation wireless access technology highly relies on nonorthogonal multiple access (NOMA) technique. This paper proposes a novel power domain cyclic spread multiple access (PDCSMA) scheme for the design of NOMA system with power domain superposition coding (SC) and cyclic spreading at the transmitter concurrent with symbol level successive interference cancellation (SL‐SIC) at the receiver. Based on acceptable difference in channel gain, the users are grouped together to form PDCSMA clusters, and the unique power is allotted to each user in a cluster. The user with good channel condition is allotted less power, and the user with poor channel condition is allotted more power. Each PDCSMA cluster has its own spreading code, and the data of every user in a cluster are cyclic spread with the same code. Each cluster supports the number of multipath components equivalent to the length of the spreading code. The use of cyclic spreading makes the signal suffered by multipath fading less prone to intra cluster interference. The user signal is decoded by minimum mean square error‐frequency domain equalization (MMSE‐FDE) or maximal ratio combining (MRC)–based receiver in which weak user is detected with hard decision, and strong user is detected with SIC. Compared with conventional power domain NOMA (PDNOMA) and interleaved NOMA, the proposed PDCSMA achieves better bit error rate (BER) performance and assures guaranteed detection.

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.

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