RADIO OVER FIBER SYSTEM AND METHOD FOR CONTROLLING TRANSMISSION TIME
First Claim
1. A Radio over Fiber (RoF) system having a base station (BS) coupled to a remote unit via an optical cable, comprising:
- an antenna configured to transmit and receive upstream and downstream Radio Frequency (RF) signals;
a first RF switch configured to selectively set an upstream or downstream RF signal path;
an RF transmit/receive amplifier configured to amplify the downstream RF signal, reduce a noise component of the upstream RF signal, and amplify a signal component of the upstream RF signal when the downstream RF signal path is set by the first RF switch;
a time delay unit configured to delay the upstream or downstream RF signal by compensating a synchronization of a transmission time of the upstream or downstream RF signal; and
a modern configured to generate a switch control signal to be used to set the upstream or downstream RF signal path,wherein a donor of the BS transmits the switch control signal generated by the modem and the downstream RF signal to the remote, receives the upstream RF signal from the remote, and measures and controls a delay time of an optical signal transmitted via the optical cable, andwherein the remote unit re-transmits a signal used to measure the delay time of the optical signal to the donor and sets a path of the upstream or downstream RF signal according to the switch control signal received from the donor.
1 Assignment
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Accused Products
Abstract
A radio-over-fiber (RoF) system and method for controlling a transmission time is provided. In a Time Division Duplex (TDD) wireless communication system comprising a Base Station (BS) having a donor and a remote connected thereto via am optical fiber, upstream and downstream Radio Frequency (RF) signals are transmitted and received, and by reliably transmitting a switch control signal to the remote and simultaneously compensating for a transmission time delay occurring in the optical cable, time synchronization of the upstream and downstream RF signals transmitted and received via antennas of the BS and the remote is controlled, thereby efficiently increasing the performance of a TDD wireless service system.
117 Citations
10 Claims
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1. A Radio over Fiber (RoF) system having a base station (BS) coupled to a remote unit via an optical cable, comprising:
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an antenna configured to transmit and receive upstream and downstream Radio Frequency (RF) signals; a first RF switch configured to selectively set an upstream or downstream RF signal path; an RF transmit/receive amplifier configured to amplify the downstream RF signal, reduce a noise component of the upstream RF signal, and amplify a signal component of the upstream RF signal when the downstream RF signal path is set by the first RF switch; a time delay unit configured to delay the upstream or downstream RF signal by compensating a synchronization of a transmission time of the upstream or downstream RF signal; and a modern configured to generate a switch control signal to be used to set the upstream or downstream RF signal path, wherein a donor of the BS transmits the switch control signal generated by the modem and the downstream RF signal to the remote, receives the upstream RF signal from the remote, and measures and controls a delay time of an optical signal transmitted via the optical cable, and wherein the remote unit re-transmits a signal used to measure the delay time of the optical signal to the donor and sets a path of the upstream or downstream RF signal according to the switch control signal received from the donor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of controlling the transmission time in a Time Division Duplexing (TDD) wireless communication system having a Base Station (BS) coupled to a remote unit via an optical cable, the method comprising:
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generating a switch control signal for setting a path of an upstream or downstream Radio Frequency (RF) signal transmitted or received between a donor of the BS and the remote and transmitting the switch control signal from the donor to the remote unit; generating and transmitting a reference signal based on a specific time in order to measure a delay time of the optical cable; combining the reference signal and the switch control signal; converting the combined signal to an optical signal and transmitting the optical signal to the remote unit; separating a portion of the optical signal and re-transmitting the portion of the optical signal to the donor; converting the optical signal re-transmitted from the remote unit to an electrical signal; detecting the reference signal by separating the reference signal to measure the delay time of the optical cable and the switch control signal from the electrical signal; comparing a transmission time of the detected reference signal and a generation time of the reference signal generated based on a specific time; if there is a time difference between the transmission time of the detected reference signal and the generation time of the reference signal generated based on the specific time, generating a time delay control signal according to the time difference between the two signals compared; and controlling a time synchronization of the upstream and downstream RF signals transmitted and received between the BS and the remote by compensating for a transmission time delay occurring in the optical cable according to the time delay control signal. - View Dependent Claims (10)
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Specification