Adaptive propagation delay compensation for TDMA communications systems

• US 6,377,565 B1
• Filed: 09/29/1998
• Issued: 04/23/2002
• Est. Priority Date: 09/29/1998
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Puckette, Charles McDonald IV
• Primary Examiner(s): TON, DANG T
• Application Number:
  US09/162,805
• Time in Patent Office: 1,302 Days
• Field of Search: 370/282, 370/278, 370/503, 370/508, 370/519, 370/442, 370/337, 370/341, 370/311, 370/321, 370/324, 370/326, 370/332, 370/333, 370/334, 370/339, 370/347, 370/350, 370/349, 370/501, 342/33, 342/36, 342/40, 342/140, 342/357, 342/463, 342/41, 375/356, 375/354, 375/355, 455/509, 455/515, 455/517, 455/502, 455/500
• US Class Current: 370/337
• CPC Class Codes: H04B 7/18504 Aircraft used as relay or high altitude atmospheric platform
• CPC Class Codes: H04J 3/0682 by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging
• CPC Class Codes: H04W 56/0045 compensating for timing error by altering transmission time

Abstract

A propagation delay compensation device and method provide adaptive propagation delay compensation in a time division multiple access (TDMA) communications system. The device includes a range computation unit and a delay computation unit. The range unit receives data signals to identify respective positions of a base station and a transceiver and, in response, generates a signal indicating line-of-sight range between the base station and the transceiver. The delay unit receives the range signal and, in response, generates a required delay which provides for alignment of communications signals received at the base station to arrive in alignment with assigned time slots at the base station. In one embodiment, the invention enables communication from aircraft through TDMA cellular systems using standard TDMA waveform formats.

Claims

1. A propagation delay compensation device for use in a time division multiple access communications system having a base station and a transceiver assigned to said base station, said device comprising:

a range computation unit for receiving a base position data signal and a transceiver position data signal and generating therefrom a measurement signal for line of sight range between said base station and said transceiver, wherein said base position data signal identifies the base station position and said transceiver position data signal identifies the transceiver position;

a transceiver position unit in communication with said range computation unit for generating said transceiver position data signal to indicate said transceiver position in a three-dimensional coordinate system wherein said time division multiple access communications system comprises a position location apparatus situated in close proximity to said transceiver position unit and said transceiver position unit being adapted to receive a transceiver position signal from said position location apparatus and to generate said transceiver position data signal from said transceiver position signal wherein said position location apparatus comprises an electronic navigation system receiver and an altimeter;

a base position unit in communication with said range computation unit for generating said base position data signal to indicate said base station position in said three-dimensional coordinate system, said base position unit is adapted to generate said base position data signal from a control signal received from said base station;

a delay computation unit for receiving said measurement signal and generating therefrom a required delay measured relative to a received communication signal transmitted from the transceiver to the base station, the required delay providing for the received communication signal to arrive at the base station in alignment with a time slot assigned thereto; and

a mobile platform comprising an airborne platform wherein said position location apparatus and said transceiver being disposed in common aboard said mobile platform wherein said altimeter is adapted to generate an indication of altitude of said airborne platform and said transceiver position signal representing transceiver position data including a transceiver altitude value corresponding to said indication of altitude, transceiver longitude data indicating longitude of said airborne platform, and transceiver latitude data indicating latitude of said airborne platform;

wherein said base station includes an antenna tower and said base position data signal represents base position data including base longitude data indicating longitude of said base station and base latitude data indicating latitude of said base station,

wherein said range computation unit comprises;

a ground distance section for computing ground distance between said airborne platform and said base station on the basis of said transceiver latitude data, said transceiver longitude data, said base latitude data, and said base longitude data;

an elevation section for computing a height difference by subtracting height of said tower from said altitude value, and

a range section for computing, as said line of sight range, the positive square root of the sum of said height difference squared and said ground distance squared.

2. A propagation delay compensation device for use in a time division multiple access communications system having a base station and a transceiver assigned to said base station, said device comprising:

a range computation unit for receiving a base position data signal and a transceiver position data signal and generating therefrom a measurement signal for line of sight range between said base station and said transceiver, wherein said base position data signal identifies the base station position and said transceiver position data signal identifies the transceiver position;

a transceiver position unit in communication with said range computation unit for generating said transceiver position data signal to indicate said transceiver position in a three-dimensional coordinate system wherein said time division multiple access communications system comprises a position location apparatus situated in close proximity to said transceiver position unit and said transceiver position unit being adapted to receive a transceiver position signal from said position location apparatus and to generate said transceiver position data signal from said transceiver position signal;

a base position unit in communication with said range computation unit for generating said base position data signal to indicate said base station position in said three-dimensional coordinate system, said base position unit is adapted to generate said base position data signal from a control signal received from said base station; and

a delay computation unit for receiving said measurement signal and generating therefrom a required delay measured relative to a received communication signal transmitted from the transceiver to the base station, the required delay providing for the received communication signal to arrive at the base station in alignment with a time slot assigned thereto,

wherein said propagation delay compensation device and said base station are disposed at a common site.

3. A propagation delay compensation device for use in a time division multiple access communications system having a base station and a transceiver assigned to said base station, said device comprising:

a range computation unit for receiving a base position data signal and a transceiver position data signal and generating therefrom a measurement signal for line of sight range between said base station and said transceiver, wherein said base position data signal identifies the base station position and said transceiver position data signal identifies the transceiver position;

a transceiver position unit in communication with said range computation unit for generating said transceiver position data signal to indicate said transceiver position in a three-dimensional coordinate system wherein said time division multiple access communications system comprises a position location apparatus situated in close proximity to said transceiver position unit and said transceiver position unit being adapted to receive a transceiver position signal from said position location apparatus and to generate said transceiver position data signal from said transceiver position signal wherein said position location apparatus comprises an electronic navigation system receiver;

a base position unit in communication with said range computation unit for generating said base position data signal to indicate said base station position in said three-dimensional coordinate system, said base position unit is adapted to generate said base position data signal from a control signal received from said base station; and

a delay computation unit for receiving said measurement signal and generating therefrom a required delay measured relative to a received communication signal transmitted from the transceiver to the base station, the required delay providing for the received communication signal to arrive at the base station in alignment with a time slot assigned thereto;

wherein said propagation delay compensation device is disposed aboard a mobile platform.

4. The propagation delay compensation device of claim 3, further comprising a synchronization adjuster for receiving said delay signal and response thereto, adjusting respective times of generation of data transmissions from said transceiver, said times of generation being adjusted for alignment of said data transmissions with respective time slots assigned thereto at said base station.

5. The propagation delay compensation device of claim 4, wherein said base station is adapted to receive said data transmissions in accordance with a time division multiple access signaling format providing the respective time slots for said data transmissions and including a guard field in each of said respective time slots.

6. The propagation delay compensation device of claim 3, wherein said position location apparatus includes an electronic navigation system receiver.

7. The propagation delay compensation device of claim 6, wherein said electronic navigation system receiver comprises a global positioning system receiver.

8. A method of propagation delay compensation, comprising the steps of:

receiving a base position data signal and a transceiver position data signal, said base position data signal identifying position of a base station in a time division multiple access communications system and said transceiver position data signal identifying position of a transceiver assigned to said base station, wherein said transceiver is disposed aboard an airborne platform;

generating an indication of altitude of said airborne platform, said transceiver position signal representing transceiver position data including an altitude value corresponding to said indication of said altitude, transceiver longitude data indicating longitude of said airborne platform, and transceiver latitude data indicating latitude of said airborne platform, said base position data signal representing base position data including base longitude data indicating longitude of said base station and base latitude data indicating latitude of said base station;

generating, from said received transceiver position data signal and said received base position data signal, a measurement signal representing a line of sight range between said transceiver and said base station, the step of generating a measurement signal comprises the steps of;

computing ground distance between said airborne platform and said base station from said transceiver latitude data, said transceiver longitude data, said base latitude data, and said base longitude data;

computing a height difference by subtracting height of an antenna tower at said base station from said altitude value; and

computing as said line of sight range the positive square root of the sum said height difference squared and said ground distance squared;

generating, from said measurement signal, a required delay measured relative to a communications signal transmitted from said transceiver and received at said base station, the required delay providing for the received communications signal to arrive in alignment with a time slot assigned thereto; and

adjusting respective times of generation of data transmissions from said transceiver in accordance with said required delay for alignment of said data transmissions with respective time slots assigned thereto at said base station.

9. The method of propagation delay compensation of claim 8, wherein said transceiver position data signal indicates position of said transceiver in a three-dimensional coordinate system and said base position data signal indicates position of said base station in said three-dimensional coordinate system.

10. The method of propagation delay compensation of claim 8, further comprising the steps of:

receiving a transceiver position signal from a position location apparatus disposed in close proximity to said transceiver;

generating said transceiver position data signal from said transceiver position signal;

receiving a control signal from said base station; and

generating said base position data signal from said control signal.

11. A method for propagation delay compensation used in a time division multiple access communications system having a base station and a transceiver assigned to said base station, the method comprising the steps of:

receiving a base position data signal and a transceiver position data signal, said base position data signal identifying position of a base station in a time division multiple access communications system and said transceiver position data signal identifying position of a transceiver assigned to said base station;

generating, from said base position data signal and said transceiver position data signal, a measurement signal for line of sight range between said base station and said transceiver;

generating said transceiver position data signal to indicate said transceiver position in a three-dimensional coordinate system;

generating said base position data signal to indicate said base station position in said three-dimensional coordinate system;

receiving said measurement signal and generating therefrom a required delay measured relative to a received communication signal transmitted from the transceiver to the base station, the required delay providing for the received communication signal to arrive at the base station in alignment with a time slot assigned thereto,

wherein said step of receiving said measurement signal and generating therefrom a required delay is performed on a mobile platform.