Ergodic Capacity Analysis and Power Optimization in Time Shared Cooperative NOMA

This work proposes a cooperative NOMA system that operates on the time-sharing model, namely TS-C-NOMA. According to this paradigm, a base station provides direct service to a cell center user (CCU), but a cell edge user (CEU), even with a direct connection with the base station, needs the CCU's cooperation (as a relay) for proper signal reception. Conventionally, a separate relay has been provided to the CEUs for signal reception. Consideration is given to a case where CEUs outnumber CCUs. The aforementioned method time-shares a CCU with numerous clustered CEUs, effectively using the various CEUs' frequency ranges, which may go unused in typical C-NOMA. Power optimization has been done with the utilization of channel state information. With the use of time-sharing and power optimization parameters, ergodic capacity is thoroughly determined. The ergodic sum capacity of the proposed scheme with fixed power allocation and optimum power allocation is analytically computed, verified by simulations, and contrasted with traditional methods to demonstrate the capacity gains attained.