In cooperative communication system, mobile users are constantly transmitting and relaying data. On the other hand, network coding has been widely investigated in communication system. In this paper, we aim to combine network coding with the conventional cooperative communication system, however, we face certain problems. The main property of cooperative system is diversity; however, when network coding operation is introduced, it violates the rules of diversity. The new signals transmitted by relays are no longer like those sent from the transmitters. In order to fix this problem, in this paper we introduce a method using a multiplier rather than the binary sum operation, which is normally used in network coding. Numerical analyses using maximum ratio combining (MRC), for performance analysis, show that the proposed method improves diversity, i.e. reliability, without deterioration of the average probability of error. Cooperative communication is widely used in consumer wireless communication.