A novel spread space-spectrum multiple access scheme for the forward link

We consider a new multiple access framework for the forward link transmission with multiple transmit and receive antennas. The primary goal is to achieve high bandwidth efficiency while the number of user-channels, rather than the individual's data rate, is to be maximized. In the proposed framework, we focus on a single spreading period, in which the data from different users are multiplexed using the space-time-diagonal (STD) spreading sequences. With a real constellation, N users/Hz/sec is achieved where N is the number of transmit and receive antenna elements. Any form of joint coding among these data over space-time cannot be considered within this period because they belong to different users. Hence, spreading over space-time becomes an effective approach for the purpose of multiplexing. Both analytical studies and simulations results show that our scheme has profound performance.