| 摘要 |
PROBLEM TO BE SOLVED: To eliminate mutual interference, to increase amplification gain, to perform relay at a long distance and also to expand a service area without reducing available radio channels by performing frequency conversion of radio frequencies for down and up. SOLUTION: A down radio frequency f1 from a radio base station 1 is amplified by an amplifier 22 and after that, is subjected to frequency conversion in a frequency conversion unit 23 to be f2 and an amplifier 24 amplifies it and transmits it toward a mobile station 3. After an amplifier 27 amplifies radio waves in a frequency F2 from the station 3, a frequency conversion unit 26 converts it into a frequency F1 and an amplifier 25 amplifies it and transmits it toward the station 1. The radio wave interference of transmission and reception is eliminated and high gain amplification becomes possible by respectively converting the down f1 and f2 and the up F1 and F2 into frequencies of in different bands. An area is easily expanded by making the frequencies f2 and F2 used with the mobile station 800 MHz band and the frequencies f1 and F1 with the base station a 1.5 GHz band. |
