Space-Time Codes for MIMO Communication

A MIMO (multiple-input, multiple-output) wireless communication system is so called because it uses multiple transmit and receive antennas. This setup can increase data transmission rates by creating multiple virtual communication streams, known as multiplexing gain. It can also improve reliability through spatial diversity, called diversity gain. Designing signals, termed as space-time codes, that achieve both gains involves a tradeoff called the diversity-multiplexing gain tradeoff (DMT).

1. Professor Kumar was the first to explicitly construct space-time codes that optimally balance this tradeoff for all fading channel models, using algebraic structures called cyclic division algebras. His well-cited work, with over 300 citations, has inspired further research in this field.

• P. Elia K.R. Kumar, S. A, Pawar, P.V. Kumar H-f Lu,"Explicit, Minimum-Delay Space-Time Codes Achieving the Diversity Multiplexing Gain Tradeoff", IEEE Trans. Inform Theory, Sep. 2006, pp. 3869-3884. (GSC: 383).

2. Perfect space-time codes are a subclass that achieve the DMT tradeoff and possess additional desirable attributes. Prior to Professor Kumar's work, perfect space time codes had only been constructed for 2, 3, 4, and 6 transmit antennas. Professor Kumar's work made it possible to construct perfect space-time codes for any number of antennas.

• Petros Elia, B. A. Sethuraman, P. Vijay Kumar,"Perfect Space-Time Codes for Any Number of Antennas", IEEE Trans. Inform. Theory, Nov 2007, vol.52, No.11, pp. 3853 - 3868.(GSC: 169)