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HBBCL Work on Space-Time Coding 

Overview of Space-Time Coding Research

With the rapid growth of the Wi-Fi market, there is also an increasing demand for higher data rates. A solution to achieving improved capacities is to employ multiple antennas at the transmitter and receiver of the wireless system. Theoretical experimental studies have shown that the capacity of a wireless channel grows linearly in minimum of the number of antennas used at both ends of the channel. Space-time coding (STC) deals with the design of good codes for multiple antenna wireless systems.

Traditionally the two scenarios of interest are noncoherent and coherent STC. In noncoherent STC neither the receiver nor the transmitter knows the channel propagation coefficients, while in coherent STC, only the receiver has knowledge of channel through training. The basic the problem in STC is to design codes with simple encoding and decoding algorithms. Here is a summary of our efforts in space-time coding:

Coherent Space-Time Codes

Knowledge of the channel state information (CSI) at the receiver simplifies the coding. In this context we constructed space-time codes for high rates using trellis codes and orthogonal designs. We also constructed variable space-time block codes for unequal error protection of the transmitted bits.

Differential and Noncoherent Space-Time Codes

We were the first to propose the use of differential detection methods for multiple antenna systems. This gives rise to unitary differential STC. Differential STC is well suited for slowly varying channels and tthe receiver does not require channel knowledge or the statistics of the propagation coefficients.

We also have constructions of noncoherent unitary space-time codes when the receiver knows the channel statistics but not the channel itself. These codes are based on generalized PSK constellations and orthogonal designs.

For further information refer to our list of publications and presentations.