Synchronous time division multiple access interrogate-respond data communication network

• US 5,428,603 A
• Filed: 09/15/1993
• Issued: 06/27/1995
• Est. Priority Date: 05/17/1993
• Status: Expired due to Term

• Current Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Kivett, James A.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Patel, Ajit
• Application Number:
  US08/122,866
• Time in Patent Office: 650 Days
• Field of Search: 370/94.2, 370/94.1, 370/85.1, 370/85.8, 370/85.13, 370/29, 370/95.1, 370/95.2, 370/18, 370/24, 370/100.1, 370/105.1
• US Class Current: 370/280
• CPC Class Codes: B61L 2205/04 Satellite based navigation systems, e.g. global positioning system [GPS]
• CPC Class Codes: B61L 27/20 Trackside control of safe travel of vehicle or train, e.g. braking curve calculation
• CPC Class Codes: B61L 3/125 using short-range radio transmission
• CPC Class Codes: G01S 5/0009 Transmission of position information to remote stations involving assistance data G01S5/0236
• CPC Class Codes: G01S 5/02695 Constraining the position to lie on a curve or surface
• CPC Class Codes: H04J 3/0652 Synchronisation among time division multiple access [TDMA] nodes, e.g. time triggered protocol [TTP] bus network with centralized control in which slots are of a TDMA packet structure H04L12/4035
• CPC Class Codes: H04J 4/00 Combined time-division and frequency-division multiplex systems H04J13/00 takes precedence ; data transmission H04L5/26; telemetry G08C15/00
• CPC Class Codes: H04L 1/004 by using forward error control H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00
• CPC Class Codes: H04L 45/00 Routing or path finding of packets in data switching networks routing or path finding in wireless networks H04W40/00
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 74/04 Scheduled access hybrid access H04W74/02
• CPC Class Codes: H04W 88/04 adapted for relaying to or from another terminal or user

Abstract

A communication network and method employing chained sequences of communications devices, to support synchronized relaying of data, thus forming duplex data buses. These data buses support both synchronous virtual circuits and a form of synchronized interrogate-respond data transfer. Off-bus communications devices are permitted to synchronously respond onto the bus without time contention.

Claims

1. A data communications network, comprising:

a network of communications devices for communication over a communications medium, said devices spatially separated and arranged along a communication path;

means for maintaining time synchronization among said communication devices;

an arrangement of coordinated time slot functional assignments, wherein a predetermined communication device can send or receive a data packet during a given time slot;

means for successively propagating in alternating time slots a first data packet along said path in a first direction from device to adjacent device and for propagating a second data packet along said path in a second direction from device to adjacent device in alternating time slots in a multi-level data relay, comprising;

means for relaying said first data packet from a first device to an adjacent device during a first time slot, said relaying of said first packet occurring in a first direction along said path;

means for relaying said second data packet from a second device to a device adjacent to said second device during a second time slot, said relaying of said second packet occurring in a second direction along said path;

means for relaying said first data packet in said first direction along said path during a third time slot to yet another device; and

means for relaying said second data packet in said second direction along said path during a fourth time slot to a further device;

wherein data packet flow occurs in both said first and second directions along said path in a time interleaved manner to form a multi-level duplex data flow.

2. The network of claim 1 wherein said communications devices are arranged to provide a repetitive duplex data flow along said path, wherein the data flow in each direction is repeated after a repeat period defined by a predetermined number of time slots.

3. The network of claim 1 wherein two devices are permitted to transmit or receive simultaneously during a particular time slot.

4. The network of claim 3 further comprising isolation means for preventing data transmitted by one of said two devices during said time slot from being received within a given area by a network device other than an intended recipient.

5. The network of claim 4 wherein said isolation means comprises means for assigning unique frequency channels for each potentially simultaneous transmission within a given area.

6. The network of claim 4 wherein said isolation means comprises transmission coding means for transmitting said data packets from one device to another within a given area.

7. The network of claim 1 further comprising a control node, and means for interrogating and obtaining responses from particular communications devices, wherein said control node issues an interrogation data packet addressed to a particular interrogated communications device, said network propagates said interrogation data packet along said data path to said particular device, and wherein said interrogated device issues a response data packet in a subsequent time slot in a return data propagation direction, wherein said response data packet is propagated along said data path back to said control device.

8. The network of claim 7 wherein said interrogate data packet comprises a data packet address identifying said interrogated communication device.

9. The network of claim 7 further comprising one or more off bus communication devices which are not assigned time slots within said network.

10. The network of claim 1 further comprising a redundant bus configuration, wherein each device is connected to two other devices in each direction along said data path, and each device listens for transmissions from two prior devices.

11. The network of claim 1 wherein said bus is configured as a branched bus comprising a plurality of data bus segments meeting at branch points.

12. A method for data communications in a network of communication devices spatially separated and arranged on a data bus, comprising a sequence of the following steps:

providing a network of communications devices, each capable of transmitting and receiving data packets on the data bus, each device comprising a real time clock;

maintaining time synchronization among real time clocks comprising said devices;

assigning particular time slots to said communication devices within a coordinated time slot structure, wherein a predetermined communications device can send or receive a data packet during a given time slot, said time slot assignments designed to permit a data packet to be relayed by said devices along the data bus in either direction in chained sequence;

successively propagating in alternating time slots a first data packet along said data bus in a first direction from device to adjacent device and for propagating a second data packet along said data bus in a second direction from device to adjacent device in a multi-level data relay, said propagating step comprising;

relaying said first data packet from a first device to an adjacent device during a first time slot, said relaying of said first packet occurring in a first direction along said data bus;

relaying said second data packet from a second device to a device adjacent to said second device during a second time slot, said relaying of said second packet occurring in a second direction along said data bus;

relaying said first data packet in said first direction along said data bus during a third time slot to yet another device; and

relaying said second data packet in said second direction along said data bus during a fourth time slot to a further device;

wherein data packet flow occurs in both directions along the data bus in a time interleaved manner to form a multi-level duplex data flow along the data bus.

13. The method of claim 12 wherein said time slot assignment structure includes repetitive windows each comprising a block of time slots, wherein the data flow in each direction along the data bus is repeated after a repeat period defined by the number of time slots between the start of said windows.

14. The method of claim 12 wherein wherein two or more devices are permitted to transmit or receive during the same time slot.

15. The method of claim 14 wherein said devices comprise radio sets for transmitting and receiving said data packets via a wireless RF communications link, and said two or more devices permitted to transmit or receive simultaneously during a given time slot are assigned different RF frequency channels for relaying said data packet during said given time slot, thereby preventing a data packet transmitted by one of said two devices during said given time slot from being received within a given area by a communication device other than an intended recipient.

16. The method of claim 14 wherein said devices comprise radio sets for transmitting and receiving said data packets via a wireless RF communications link, and said radio sets employ transmission coding for transmitting data packets from one device to another within a given area.

17. The method of claim 12, wherein said network further includes a control communication device, and said method further comprises the steps of interrogating and obtaining responses from particular communications devices, wherein said control device issues an interrogation data packet addressed to a particular interrogated communications device, said interrogation data packet is relayed along the data bus to said particular device, and wherein said interrogated device issues a response data packet in a subsequent time slot in a return data propagation direction, wherein said response data packet is propagated along said data path back to said control device.

18. The method of claim 17 wherein said interrogate data packet comprises a data packet address identifying said interrogated communication device.

19. The method of claim 17 wherein said interrogated communication device is off the data bus and is not assigned time slots within said network.

20. The method of claim 12 wherein each device is connected to two other devices in each direction along the data bus, and each device listens for transmissions from two prior devices during its assigned time slots.

21. The method of claim 12 wherein the data bus is configured as a branched bus comprising a plurality of data bus segments meeting at branch points.

22. A data communications network, comprising:

a network of communications devices for communication over a communications medium, said devices spatially separated and arranged along a communication path, said network comprising means for maintaining time synchronization among said devices, said communications devices arranged to provide a repetitive duplex data flow along said path, and wherein two of said devices are permitted to simultaneously transmit or receive during a particular time slot;

an arrangement of coordinated time slot functional assignments, wherein a predetermined communication device can send or receive a data packet during a given time slot;

means for successively propagating a first data packet along said path in a first direction from device to adjacent device and for propagating a second data packet along said path in a second direction from device to adjacent device in alternating time slots, comprising means for relaying said first data packet from a first device to an adjacent device during a first time slot, said relaying of said first packet occurring in a first direction along said path;

means for relaying said second data packet from a second device to a device adjacent to said second device during a second time slot, said relaying of said second packet occurring in a second direction along said path, wherein data packet flow occurs in both directions along said path in a time interleaved manner to form a duplex data flow; and

isolation means for preventing data transmitted by one of said two devices during a given time slot from being received within a given area by a network device other than an intended recipient, said isolation means comprises transmission coding means for transmitting said data packets from one device to another within said given area, said transmission coding means comprising direct sequence spread spectrum coding means.

23. A method for data communications in a network of communication devices spatially separated and arranged on a data bus, comprising a sequence of the following steps:

providing a network of communications devices, each capable of transmitting and receiving data packets on the data bus, each device comprising a real time clock, and wherein said devices comprise radio sets for transmitting and receiving said data packets via a wireless RF communications link, and said radio sets employ direct sequence spread spectrum transmission coding for transmitting data packets from one device to another within a given area;

maintaining time synchronization among real time clocks comprising said devices;

assigning particular time slots to said communication devices within a coordinated time slot structure, wherein a predetermined communications device can send or receive a data packet during a given time slot, said time slot assignments designed to permit a data packet to be relayed by said devices along the data bus in either direction in chained sequence, and wherein two or more devices are permitted to simultaneously transmit or receive during a given time slot;

successively propagating a first data packet along said data bus in a first direction from device to adjacent device and for propagating a second data packet along said data bus in a second direction from device to adjacent device in alternating time slots in a multi-level data relay, comprising relaying said first data packet from a first device to an adjacent device during a first time slot, said relaying of said first packet occurring in said first direction along said data bus, relaying said second data packet from a second device to a device adjacent to said second device during a second time slot, said relaying of said second packet occurring in said second direction along said data bus, relaying said first data packet in said first direction along said data bus during a third time slot to yet another device, and relaying said second data packet in said second direction along said data bus during a fourth time slot to a further device, wherein data packet flow occurs in both directions along the data bus in a time interleaved manner to form a multi-level duplex data flow along the data bus.

24. A data communications network, comprising:

a network of communications devices for communication over a communications medium, each of said devices comprising a wireless radio set for transmission and reception of spread spectrum encoded signals, said devices spatially separated and arranged along a communication path, said network comprising means for maintaining time synchronization among said devices;

an arrangement of coordinated time slot functional assignments, wherein a predetermined communication device can send or receive a data packet during a given time slot;

means for successively propagating a first data packet along said path in a first direction from device to adjacent device and for propagating a second data packet along said path in a second direction from device to adjacent device in alternating time slots in a multi-level data relay comprising means for relaying said first data packet from a first device to an adjacent device during a first time slot, said relaying of said first packet occurring in said first direction along said path, means for relaying said second data packet from a second device to a device adjacent to said second device during a second time slot, said relaying of said second packet occurring in said second direction along said path means for relaying said second data packet in said second direction along said path during a fourth time slot to a further device means for relaying said first data packet in said first direction along said path during a third time slot to yet another device, and means for relaying said second data packet in said second direction along said path during a fourth time slot to a further device, wherein data packet flow occurs in in a time interleaved manner to form a multi-level duplex data flow.