Frame synchronization in multi-cell systems with a data interface
First Claim
1. A method for synchronizing transmission of first data frames from a plurality of base stations which receive second data frames at different times from a central unit due to different signal propagation delays, comprising:
- determining a signal propagation delay to each base station;
storing the signal propagation delay in each respective base station;
transmitting known data in the second data frames from the central unit to the base stations to initiate frame synchronization; and
delaying transmission of the first data frames from each base station by an amount determined from the stored signal propagation delay.
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Accused Products
Abstract
A method of timing in a multi-cell system requiring synchronization of frames in transmission is provided. Transceivers of a wired data interface between a central controller and multiple base stations are synchronized to a frame timing clock up to a difference in propagation delays between the central controller and multiple base stations. The propagation delays are considered as constants, are measured, and are stored in each base station. A unique word is regularly inserted in the data transmitted by the central controller, at a fixed interval. When this unique word is detected by the base station within a fixed period of the frame timing clock, a frame signal delay is initiated at the next rising edge of each frame timing clock. This frame signal delay is equal to the period of the frame timing clock minus the propagation delay. At the end of the frame delay, the frame data is transmitted, and all frames are simultaneously transmitted from different base stations.
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Citations
22 Claims
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1. A method for synchronizing transmission of first data frames from a plurality of base stations which receive second data frames at different times from a central unit due to different signal propagation delays, comprising:
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determining a signal propagation delay to each base station; storing the signal propagation delay in each respective base station; transmitting known data in the second data frames from the central unit to the base stations to initiate frame synchronization; and delaying transmission of the first data frames from each base station by an amount determined from the stored signal propagation delay. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for synchronizing transmission of first data frames from a plurality of base stations which receive second data frames at different times from a central unit due to different signal propagation delays, comprising:
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receiving a master clock signal and a unique word at all base stations; deriving a fast clock signal from the master clock signal at all base stations; detecting the unique word at each base station to begin frame synchronization; and delaying transmission of the first data frames from each base station by an amount determined from a stored signal propagation delay, a frequency of the master clock signal, and a frequency of the fast clock signal. - View Dependent Claims (9, 10, 11, 12)
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13. A system for synchronizing transmission of first data frames from a plurality of base stations which receive second data frames at different times from a central unit due to different signal propagation delays, comprising:
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means for storing the signal propagation delay in each respective base station; means for transmitting known data in the second data frames from the central unit to the base stations to initiate frame synchronization; and means for delaying transmission of the first data frames from each base station by an amount determined from the stored signal propagation delay. - View Dependent Claims (14, 15, 16, 17)
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18. An apparatus for synchronizing transmission of first data frames from a plurality of base stations which receive second data frames at different times from a central unit due to different signal propagation delays, comprising:
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means for receiving a master clock signal and a unique word at all base stations; means for deriving a fast clock signal from the master clock signal at all base stations; means for detecting the unique word at each base station to begin frame synchronization; and means for delaying transmission of the first data frames from each base station by an amount determined from a stored signal propagation delay, a frequency of the master clock signal, and a frequency of the fast clock signal. - View Dependent Claims (19, 20, 21, 22)
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Specification