| 摘要 |
PURPOSE:To obtain a high frequency utilizing factor by using a nondirectional antenna when D/U reaches a predetermined value or below during communication with a directional antenna and switching the antenna into the directional antenna with a large D/U so as to use the same frequency repetitively. CONSTITUTION:Sectors 6, 7 are regions covered by 180 deg. directional antennas 9, 10 and an omni-zone 8 is a region covered by a nondirectional antenna 11. A channel of the sane frequency is assigned to the sectors 6, 7 and a channel of a different frequency is assigned to the omni-zone 8. With a desired wave versus disturbing wave ratio (D/U) at 15dB as a required value, in taking a difference (F/B) between the gain of the directivity of the antenna and the gain in other directions as 20dB, mobile sets are distributed uniformly in the sector 6 and mobile sets giving interference are distributed uniformly, then nearly 35% of the total calls is below the D/U 15dB. The calls are switched to an idle channel of the omni-zone 8 so as to allow the remaining 65% calls to use the same frequency. |
