One of the main challenges in the wireless broadcast channels is the co-channel interference among multiple destinations. Practical linear precoding techniques such as zero-forcing beamforming (ZFBF) is used to avoid the co-channel interference. However, the achievable diversity order of the ZFBF is bounded by the number of transmitter antennas. In this paper, we introduce a spectral efficient cooperative broadcast channels transmission protocol in the MISO channels using linear precoding. We evaluate the performance of the proposed protocol using the diversity and multiplexing tradeoff. The proposed protocol can achieve the maximum diversity order expressed as a sum of the transmitter antennas and the number of participating relays. For a large number of relay candidates, the diversity and multiplexing tradeoff of the proposed protocol completely surpasses the performance of the comparable scheme. Simulations have also shown the outage probability of the proposed protocol outperforms the existing scheme.