The demands for greater capacity and lower transmitted power have historically motivated research in spatial diversity systems. Diversity techniques have been implemented in many current systems and have been shown to reduce the transmit power required to maintain acceptable system performance. Traditionally spatial diversity is based on the transmission and reception of a single stream of symbols through independent and spatially separated propagation channels. In more recent developments, space-time coding and array processing techniques use diversity concepts to resolve multiple independent streams of data and increase the potential data-rate. This new space-time research investigates the unprecedented ability to simultaneously transmit separate data streams from many closely-spaced antennas on a common carrier frequency. The effectiveness of these multi-element arrays in communication systems has been found to depend on antenna design and specific characteristics of the propagation channels. This thesis describes an effort to characterize an indoor office environment with respect to these applications.
Theoretical analyses have demonstrated a relationship between the theoretical capacity of multi-element array systems with the cross-correlation of spatially separated channels. Historical measurements have also shown that in the presence of Rayleigh fading, antenna spacing may be used to control the level of correlation between propagation channels and maximize the diversity gain, or potential system capacity of a space-time system. Both the design of the antenna arrays and characteristics of the propagation environment influence a system's potential capacity.
This thesis describes the construction of a measurement system and the use of this system to evaluate the capacity gains of multi-element arrays in a wireless communication system. The presented system is capable of measuring the channel gains between a number of transmitter and receiver antenna elements and calculating both the cross-correlation between channel gains and the theoretical system capacity. After a discussion of previous research, the measurement system and subsequent measurement results are described. / Master of Science
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/31730 |
| Date | 22 April 2002 |
| Creators | Aron, Jason S. |
| Contributors | Electrical and Computer Engineering, Rappaport, Theodore S., Raman, Sanjay, Sweeney, Dennis G. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf, application/pdf, application/pdf, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | thesis_part1.pdf, thesis_part3.pdf, thesis_part5.pdf, thesis_part4.pdf, thesis_part2.pdf |
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