Cooperative communication is communications that cooperate with another user as and form a virtual array so that can balance the benefits of space diversity systems. In this paper proposed cooperative communication in the building, where two users used as the source, one user as a destination, and six user wich raised randomly as the relay. This research focus examined cross layer optimization which physical layer (example total power consumption) and network layer (example routing and traffic rate ) that influeced by congestion control. Results of examination are chosening the relay on basically of traffic rate, total power consumption, and joint oiptimization of both. And also, mean of traffic rate for source 1 is smaller than source 2 while mean of total power consumption for source 1 is bigger thatn source 2. and varian of traffic rate and total power consumption for source 1 is bigger than source 2.