Self-configuring radio network

• US 6,594,273 B1
• Filed: 07/09/1999
• Issued: 07/15/2003
• Est. Priority Date: 07/09/1999
• Status: Expired due to Term

• Current Assignee: Telecommunications Research Laboratories
• Original Assignee: Telecommunications Research Laboratories
• Inventors: McGibney, Grant
• Primary Examiner(s): Vincent, David
• Assistant Examiner(s): Sam, Phirin
• Application Number:
  US09/350,215
• Time in Patent Office: 1,467 Days
• Field of Search: 370/442, 370/310.2, 370/312, 370/313, 370/314, 370/315, 370/316, 370/321, 370/324, 370/326, 370/328, 370/329, 370/330, 370/334, 370/336, 370/337, 370/345, 370/347, 370/350, 370/389, 370/432, 370/401, 370/402, 370/404, 455/428, 455/416, 455/415, 455/502, 455/503
• US Class Current: 370/442
• CPC Class Codes: H04W 88/04 adapted for relaying to or from another terminal or user

Abstract

The invention is a radio terminal that co-ordinates with similar terminals around it to form a time division multiple access (TDMA) network. No base station or special devices are needed to manage the network. The terminals autonomously establish the critical functions that form the backbone of the network including routing and synchronization. Once established, any terminal can send radio messages through the network using any modulation format, analogue or digital, that meets the network'"'"'s bandwidth, timing, and power specification. Terminals are able to reach destinations beyond their range by routing signals through neighboring terminals. The routing algorithm is simplified considerably by exploiting the broadcast nature of radio waves and allowing the signal to take more than one path through the network at the same time. For network synchronization, each terminal acts as both a slave, locking its clock frequency to the rest of the network, and a master, pushing the network frequency to match its own reference. In a simplified embodiment of the invention, the terminal accesses the network but does not participate in routing or synchronization. This allows battery-powered devices such as handheld terminals to access the network.

Claims

1. A telecommunications network, in which the telecommunications network uses TDMA frames, each TDMA frame being divided into a series of time slots, and each time slot being divided into sub-slots, comprising:

plural active terminals and plural passive terminals;

each active terminal comprising an rf section, a transceiver, a synchronizer and a signal router, each of the transceiver, synchronizer and signal router being operably connected to the rf section for transmitting and receiving signals from the active terminal;

each signal router being configured to receive a signal in a sub-slot and re-broadcast the signal in a subsequent sub-slot when the measured energy in the signal exceeds a threshold; and

each passive terminal comprising a transceiver and synchronizer and not having a signal router.

2. The telecommunications network of claim 1 in which the subsequent sub-slot is the next adjacent sub-slot in time.

3. The telecommunications network of claim 2 in which each signal router is configured to re-broadcast a signal once during any given slot.

4. The telecommunications network of claim 3 in which the signal router is configured to prevent re-broadcast of signals across slot boundaries.

5. The telecommunications network of claim 1 in which the transceiver outputs a wideband signal.

6. A terminal for a telecommunications network, in which the telecommunications network uses TDMA frames, each TDMA frame being divided into a series of time slots, and each time slot being divided into sub-slots, the terminal comprising:

an rf section, a transceiver for transmitting signals, a synchronizer for synchronizing the terminal with respect to TDMA frames, and a signal router, each of the transceiver, synchronizer and signal router being operably connected to the rf section for transmitting and receiving signals to and from the terminal; and

the signal router being configured to receive a signal in a sub-slot and re-broadcast the signal in a subsequent sub-slot when the measured energy in the signal exceeds a threshold.

7. The terminal of claim 6 in which the subsequent sub-slot is the next adjacent sub-slot in time.

8. The terminal of claim 7 in which the signal router is configured to re-broadcast a signal once during any given slot.

9. The terminal of claim 8 in which the signal router is configured to prevent re-broadcast of signals across slot boundaries.

10. The terminal of claim 8 in which the transceiver outputs a wideband signal.

11. A synchronizer for a terminal in a telecommunications system, comprising:

a reference clock;

a signal detector having as input signal sources outside of the terminal;

an offset calculation unit connected to each of the reference clock and the signal detector and having as output a signal representing timing error;

a feedback loop responsive to the timing error for adjusting the reference clock to force the timing error to zero;

a synchronization signal generator responsive to the reference clock; and

a controller configured to advance the synchronization signal by an amount that increases as the frequency of the reference clock decreases.

12. A method of routing signals in a telecommunication network, in which the telecommunications network comprises plural terminals, and in which the telecommunications network uses TDMA frames, each TDMA frame being divided into a series of time slots, and each time slot being divided into sub-slots, the method comprising the steps of:

transmitting a signal from a first terminal in a first sub-slot; and

receiving the signal at other terminals in the network in the first sub-slot and re-broadcasting the signal in a sub-slot subsequent to the first sub-slot.

13. The method of claim 12 in which the subsequent sub-slot is the next adjacent sub-slot in time.

14. The method of claim 13 in which the terminal re-broadcasts a signal once during any given slot.

15. The method of claim 14 in which the terminal prevents re-broadcast of signals across slot boundaries.

16. The method of claim 12 in which the terminal outputs a wideband signal.

17. A method of synchronizing a telecommunications network, in which the telecommunications network comprises plural terminals, and in which the telecommunications network uses TDMA frames, each TDMA frame being divided into a series of time slots, and each time slot being divided into sub-slots;

the method comprising repeating, from time to time, the steps of;

combining synchronization signals at each of plural terminals in the network where the synchronization signals are received from terminals in the network; and

adjusting a reference clock at each of the plural terminals to reduce timing offset of the reference clock from the combined synchronization signals.

18. The method of claim 17 further comprising the step of:

advancing synchronization signals transmitted by the terminals in the network by an amount that increases as the frequency of the respective reference clocks decreases.

19. The method of claim 18 in which combining the synchronization signals comprises the steps of:

forming a magnitude-delay profile of the received signals; and

calculating a representative value of the magnitude-delay profile.

20. The method of claim 19 in which the representative value is the centroid of the magnitude-delay profile.

21. The method of claim 17 in which terminals in the network either combine synchronization signals or transmit synchronization signals but not both.

22. The method of claim 21 in which the terminals that combine synchronization signals are selected randomly from time to time from the terminals in the network.

23. The method of claim 22 in which a synchronization signal received for combination at a terminal is rejected when the power level of the synchronization signal falls below a threshold.

24. The method of claim 21 in which transmission of synchronization signals by a terminal in the network is stopped when the level of the synchronization signal received for combination at the terminal exceeds a threshold.