Bit error rate performance analysis of ACMAP in multiple input single output wireless relay network In this paper, we propose a joint decoding scheme called ACMAP decoder for multiple input single output (MISO) wireless cooperative communication network that consists of single source, single relay, and single destination. The proposed scheme is based on both Alamouti combining (AC) scheme and maximum a posteriori (MAP) decoder and is used to estimate the data at the destination. The ACMAP decoder is optimal in the sense that it minimizes the endtoend bit error rate (BER). In order to analyze performance of the proposed decoder, we derive a closed form expression for the upper bound (UB) on the endtoend error probability. Distances between system nodes, transmit energy, and channel noise and fading effects are considered in the derivation of the UB. Numerical results show that the closed form UB is very tight and it almost coincides with the exact BER results obtained from simulations. Therefore, we use the derived UB expression to study the effects of the relay position on the BER performance and to find the optimal location of the relay node.

Performance Analysis of Cooperative NOMA Networks with Imperfect CSI over Nakagamim Fading Channels In this paper, we investigate a downlink cooperative nonorthogonal multiple access (NOMA) network with decodeandforward relaying, where two scenarios of user relaying with direct link and user relaying without direct link are discussed in detail. More particularly, the performance of cooperative NOMA system under the assumption of imperfect channel state information (ipCSI) is studied over Nakagamim fading channels. To evaluate the outage performance of the above discussed two scenarios, the closedform expressions of outage probability for a pair of users are derived carefully. The diversity orders of users are achieved in the high signaltonoise region. An error floor appears in the outage probability owing to the existence of channel estimation errors under ipCSI conditions. Simulation results verify the validity of our analysis and show that: (1) NOMA is superior to conventional orthogonal multiple access; (2) The best user relaying location for cooperative NOMA networks should be near to the base station; and (3) The outage performance of distant user with direct link significantly outperforms distant user without direct link by comparing the two scenarios.