Abstract
This paper considers the use of directional antennas in broadband radio access systems to overcome the effects of i.s.i. due to multipath dispersion. It introduces a "spatial model" which considers scattering from randomly-distributed obstructions in the environment. Using this model the mean power-delay profile is estimated for various situations. It is shown that this leads to an asymptotic power law for the power-delay profile, unlike the exponential profile commonly assumed, and that this also results in difficulties in calculating the delay spread. We propose that obstructions close to either antenna should be treated as reflectors, rather than scatterers, and we then use this model to calculate the delay-spread in three scenarios involving directional antennas, with and without LOS paths. It is shown that the presence of the LOS path provides a substantial improvement, and that whereas only one directional antenna further reduces delay spread by a factor of about 2, directional antennas at both ends make a very significant difference: a factor of about 20.
| Original language | English |
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| Pages (from-to) | 8/1-X |
| Journal | IEE Colloquium (Digest) |
| Issue number | 443 |
| Publication status | Published - 1998 |