Space-Time Code Design for Multiple-Access Channels With Quantized Feedback

We investigate how to design space-time block codes for multiple access channels with full diversity and low decoding complexity for any number of transmitters and one receiver with quantized feedback. We provide the details of our scheme for four transmitters and four antennas. Each transmitter sends codewords to the receiver at the same time. We propose a codebook design and feedback scheme that combines space-time block coding and array processing. To the best of our knowledge, this is the first scheme with quantized feedback that can achieve low-complexity decoding and full diversity for any number of users when all users transmit at the same time.