Method and apparatus for adapting a time division duplex timing device for propagation delay
First Claim
1. An adjustable Time Division Duplex (TDD) timer for a communication system, comprising:
- a timer engine integrated circuit (IC) providing fixed time slices each having fixed duration transmit and receive portions and a fixed duration central guard band at a fixed driving clock frequency;
a clock input to the timer engine; and
a clock halt signal to the clock input, adapted to halt the clock input when the clock halt signal is enabled;
wherein an adjustable central guard band is provided by enabling the clock halt signal at a predetermined time point within the fixed duration central guard band in each time slice for a predetermined duration, and wherein the clock halt signal is also used to provide guard bands at each end of each time slice to provide thereby in each time slice three guard bands, the guard bands at the beginning and end of each time slice being equal in time duration.
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Accused Products
Abstract
A Time Division Duplex (TDD) wireless system utilizes an identical TDD IC engine in both base station and remote stations. In the base station the clock input to the TDD IC is halted once in the middle of each time slice to provide a central guard band between transmit and receive portions that determines the maximum range of the system. At the remote stations clock halts are programmed and utilized to provide guard bands to position transmit and receive portions in each time slice to accommodate propagation delay based on separation of a remote station from the base station. In a preferred embodiment the remote stations determine range to the base and a controller programs clock halts based on the range finding. In one aspect a TDD IC engine is used with a minimum fixed central guard band and a time slice of a first duration at a first clock frequency. Clock frequency is increased and the clock halted to provide increased range at the same time slice duration. The same IC engine at the remote stations is operated at the higher frequency and clock halts used to provide the same time slice duration of the base station and to space the transmit and receive portions of the time slice properly to accommodate propagation delay.
62 Citations
13 Claims
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1. An adjustable Time Division Duplex (TDD) timer for a communication system, comprising:
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a timer engine integrated circuit (IC) providing fixed time slices each having fixed duration transmit and receive portions and a fixed duration central guard band at a fixed driving clock frequency; a clock input to the timer engine; and a clock halt signal to the clock input, adapted to halt the clock input when the clock halt signal is enabled; wherein an adjustable central guard band is provided by enabling the clock halt signal at a predetermined time point within the fixed duration central guard band in each time slice for a predetermined duration, and wherein the clock halt signal is also used to provide guard bands at each end of each time slice to provide thereby in each time slice three guard bands, the guard bands at the beginning and end of each time slice being equal in time duration. - View Dependent Claims (2)
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3. A method for adjusting timing for a Time Division Duplex (TDD) IC engine having a first time slice duration and a first duration central guard band separating a transmit and a receive portion at a first clock input frequency, comprising steps of:
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(a) providing a second clock input frequency higher than the first clock input frequency;
thereby shortening the uninterrupted duration of the time slice and each transmit and receive portion proportionally; and(b) halting the clock input for a predetermined time period during the central guard band, thereby increasing the time duration of the central guard band such that the time slice at the second frequency is equal to the time slice at the first frequency. - View Dependent Claims (4, 5)
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6. A Time Delay Compensator (TDC) for a Time Division Duplex (TDD) station, comprising:
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at least one TDD integrated circuit (IC) engine having a clock input and adapted to provide fixed duration time slices with fixed duration transmit and receive portions and a fixed duration central guard band at a first clock input frequency; a field programmable gate array adapted to provide a repeating clock halt signal to the clock input;
wherein the clock input is halted more than once in each time slice, thereby providing plural guard bands in each time slice; anda controller adapted to program the repeating clock halt signal to adjust time duration of clock halts for each time slice provided by the TDD IC engine wherein clock halts are provided by the clock halt signal during the central guard band and at the beginning and end of each time slice equally thereby adjusting guard band duration and time slice duration. - View Dependent Claims (7)
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8. A wireless communication system comprising:
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a base station comprising a Time Division Duplex (TDD) integrated circuit (IC) engine adapted to provide successive time slices each having a central guard band dividing the time slice into equal transmit and receive portions; and a second station separated from the base station by a first distance imposing a propagation delay time for signals transmitted between the base station and the second station, the second station comprising a TDD IC engine the same as the TDD IC engine of the base station, the TDD IC engine at the second station having a clock input connected to clock halt control circuitry adapted to periodically stop the clock to the TDD IC engine; wherein an adjustable central guard band is provided by enabling the clock halt signal at a predetermined time point within the fixed duration central guard band in each time slice for a predetermined duration, and wherein the clock halt signal is also used to provide guard bands at each end of each time slice to provide thereby in each time slice three guard bands, the guard bands at the beginning and end of each time slice being equal in time duration, thereby offsetting transmit and receive portions in time at the second station from transmit and receive portions at the base station by the time duration of the propagation delay. - View Dependent Claims (9, 10, 11)
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12. In a wireless communication system comprising a base station separated from a second station by a distance determining a propagation delay, each station operating with a Time Division Duplex (TDD) integrated circuit (IC) engine providing successive time slices each having transmit and receive portions separated by a fixed-duration central guard band, a method for providing and adjusting guard bands at the second station to accommodate the propagation delay, comprising steps of:
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(a) operating an iterative range finder between the stations to determine the separation of the stations; and (b) programming a clock halt circuitry in the second station to provide an adjustable central guard band by enabling the clock halt signal at a predetermined time point within the fixed duration guard band in each time slice for a predetermined duration, and guard bands at each end of each time slice to provide in each time slice three guard bands, the guard bands at the beginning and end of each time slice being equal in time duration, thereby offsetting transmit and receive portions in time at the second station from transmit and receive portions at the base station by the time duration of the propagation delay. - View Dependent Claims (13)
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Specification