In this paper, the suitability of contention parameters that influence the heterogeneous network performance is investigated using cooperative contention-based bandwidth request BR scheme. The proposed scheme is unique since contention BR is carried out by wireless local area network WLAN/worldwide interoperability for microwave access WiMAX gateways WWG besides other mobile stations. To improve the contention efficiency with reduced access delay in contention mechanism, we propose failure models by including collision due to contention, channel error, improper detection of code and unavailability of bandwidth. In addition, for effective transmission of BR under these conditions, the stations at various hops update their contention window by appropriate consideration of transmission failure. Upon robust update of contention window, we investigate the cooperative BR by deriving the overall contention efficiency and access delay in heterogeneous networks. Simulation results validate the effectiveness of the derived model.