Space Time Block Code for Next Generation Multi-user MIMO Systems

Space-time block codes (STBCs) based single user multiplexing techniques are already part of the LTE standard. However, the rapid increase in demand for high speed and reliable communications is propelling us towards the next generation cellular networks. Multi-user MIMO based techniques are a promising candidate to meet this demand. In this paper, an STBC is designed for a multi-user MIMO system containing two users, transmitting independently. The transmission matrix is designed with the criterion of maximizing coding gain for the two users. Further, the proposed STBC enables independent decoding of symbols of both the users. A pair-wise maximum likelihood (ML) decoder for the proposed STBC is also derived. The performance of the proposed STBC is compared with the existing work and it is shown through simulations that the proposed code design performs significantly better than the existing STBC.