Showing papers by "Timothy A. Thomas published in 2008"

Method and apparatus for choosing a modulation and coding rate in a multi-user, mimo communication system

Abstract: A method and apparatus for choosing a modulation and coding rate in a MU-MIMO communication system is provided herein. During operation, a node will determine the MCR to feed back to the base even though the mobile does not know which of the possible interferers (if any) will be using the same time/frequency resources as the mobile. This takes place via the mobile node calculating best antenna weights (codebook choice) for each group of subcarriers that can be potentially used by the mobile. Transmit weights v for each interferer are then determined and the weights are utilized to determine a best modulation and coding rate for the mobile.

An Experimental 8x8 System Used to Characterize the Spatial Channel at 3.5 GHz

Abstract: Motorola Labs has developed a 20 MHz experimental wide-area mobile multi-antenna system with which to characterize the spatial channel. This system transmits OFDM waveforms from an eight-element array in each of three sectors at the base to an eight-element mobile receive array. In addition, two carrier frequencies are simultaneously transmitted and received, thus providing both FDD and TDD data. The received waveforms are post-processed to extract various channel characteristics such as time of arrivals (TOAs), Doppler frequencies (DFs), and directions of departure (DODs) at the base. This paper describes key components and parameters of this system and describes the spatial characteristics uncovered from the collected field data.