• Hardware Discussion of a MIMO Wireless Communication System Using Orthogonal Space Time Block Codes

      Potter, Chris; Kosbar, Kurt; Panagos, Adam; Missouri University of Science and Technology; Dynetics, Inc. (International Foundation for Telemetering, 2008-10)
      Although multiple-input multiple-output (MIMO) systems have become increasingly popular, the existence of real time results to compare with those predicted by theory is still surprisingly limited. In this work the hardware description of a MIMO wireless communication system using orthogonal space time block codes (OSTBC) is discussed for two antennas at both the transmitter and receiver. A numerical example for a frequency flat time correlated channel is given to show the impact of channel estimation.
    • MIMO Channel Prediction Using Recurrent Neural Networks

      Potter, Chris; Kosbar, Kurt; Panagos, Adam; Missouri University of Science and Technology; Dynetics, Inc. (International Foundation for Telemetering, 2008-10)
      Adaptive modulation is a communication technique capable of maximizing throughput while guaranteeing a fixed symbol error rate (SER). However, this technique requires instantaneous channel state information at the transmitter. This can be obtained by predicting channel states at the receiver and feeding them back to the transmitter. Existing algorithms used to predict single-input single-output (SISO) channels with recurrent neural networks (RNN) are extended to multiple-input multiple-output (MIMO) channels for use with adaptive modulation and their performance is demonstrated in several examples.
    • New Results in Unitary Space-Time Code Construction and Comparison to Upper Bounds

      Panagos, Adam; Potter, Chris; Kosbar, Kurt; Dynetics, Inc.; Missouri University of Science and Technology (International Foundation for Telemetering, 2008-10)
      Unitary space-time codes are a coding technique for unknown (i.e. non-coherent) multiple-input multiple-output (MIMO) channels. The unitary constellation symbol-error rate performance is determined by the diversity product and diversity sum metrics of the constellation. Numerous techniques have been presented over the last few years for constructing unitary space-time codes with continually improving diversity products and sums. Other work has focused on determining bounds on the optimal diversity product and sum for a given number of transmit antennas and constellation size. This paper presents a comprehensive survey of known construction techniques and bounds for unitary space-time codes, and also reports a variety of new constellations that have been constructed with improved diversity product or sum. These new constellations are documented along with a list of the currently best known codes and bounds. In many cases, a large gap between the bound and best known constellation exist. This result suggests areas of focus for improved constructions or tighter bounds.