Method and apparatus for autonomous adaptive frequency assignment in TDMA portable radio systems

• US 5,212,831 A
• Filed: 11/28/1990
• Issued: 05/18/1993
• Est. Priority Date: 11/28/1990
• Status: Expired due to Term

• Current Assignee: Telcordia Technologies Incorporated (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Bell Communications Research, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Chuang, Justin C., Sollenberger, Nelson R.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): CHAROUEL, LISA
• Application Number:
  US07/619,059
• Time in Patent Office: 902 Days
• Field of Search: 455/33.1, 455/33.2, 455/33.4, 455/34.1, 455/34.2, 455/53.1, 455/54.1, 455/56.1, 455/62, 455/63, 455/67.3, 455/67.6, 379/59, 379/61, 379/63
• US Class Current: 455/450
• CPC Class Codes: H04B 7/2643 using time-division multiple access [TDMA] H04B7/2615, H04B7/2618 take precedence
• CPC Class Codes: H04W 16/10 Dynamic resource partitioning
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• CPC Class Codes: H04W 28/16 Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
• CPC Class Codes: H04W 88/085 Access point devices with remote components

Abstract

To assign and coordinate radio frequencies at the fixed ports (30, 40, 50, 70) of a frequency-reusing radio communications system (5), most existing methods require pre-engineering or impose high complexity in system controller and port hardware. A simple autonomous procedure performed by each port to determine its own transmitting frequency and corresponding receiving frequency is disclosed. This procedure consists of signal strength measurements and an algorithm which selects the frequency with minimum interference from other ports. In particular, a port turns off (202) its own transmitter (306) and scans (203) all the candidate transmitter frequencies and measures (312) signal powers form the other ports. The frequency channel with the lowest received power is tentatively assigned (204) for downlink transmission by that port. This procedure is repeated by all the ports either independently and asynchronously or with a coordinated schedule. This cycle is repeated for either a predetermined number of iterations that is sufficient to stabilize the frequency-reuse pattern, or until no port requests a change in its assigned frequency for two consecutive cycles thereby indicating the convergence of the algorithm. This algorithm stabilizes rapidly, while adapting to changing operational conditions, such as the installation of new ports, which changes the system configuration, or the addition of new buildings which creates different interference patterns in the signal propagation paths.

Claims

1. A method of assigning radio frequencies in a frequency-reusing radio communications system having a plurality of fixed base units and a plurality of mobile transceivers, each fixed base unit having a transmitter for transmitting at an assigned downlink frequency to at least one mobile transceiver, a receiver for receiving at an associated uplink frequency from said at least one mobile transceiver and for receiving at all the downlink frequencies being transmitted by the other of the plurality of fixed base units in the system, and means for measuring the power level of signals received at all the possible different downlink frequencies from the other of the plurality of fixed base units in the system, comprising the steps of:

(a) turning off the transmitter at a first base unit;

(b) tuning the receiver at that first base unit to each possible downlink frequency;

(c) measuring at that first base unit the power level of the downlink signals received at each of the possible downlink frequencies from the other of the plurality of fixed base units in the system;

(d) determining at that first base unit the downlink frequency associated with the lowest measured power level;

(e) assigning and setting the downlink frequency at that first base unit to the downlink frequency determined in step (d);

(f) turning on the transmitter at that first base unit with its transmitting downlink frequency being set at the frequency set in step (e);

(g) repeating steps (a) through (f) at each of the other of the plurality of base units in the system; and

(h) after each of the plurality of base units in the system has its downlink frequency set in accordance with steps (a) through (f), repeating steps (a) through (g) to update the assignment of downlink frequencies to each of the base units.

2. A method in accordance with claim 1 wherein in step (h) each base unit independently waits a random time before repeating steps (a) through (f).

3. A method in accordance with claim 1 wherein step (h) repeats steps (a) through (f) at each base unit a predetermined number of times.

4. A method in accordance with claim 1 wherein a signal generated by a central controller initiates the start of steps (a) through (f) at each base unit.

5. A method in accordance with claim 1 wherein step (h) repeats steps (a) through (g) until no base unit sets its downlink frequency to a new downlink frequency in two consecutive repeats of steps (a) through (g).

6. A method of assigning radio frequencies in a TDM/TDMA digital telephony system having a plurality of fixed ports and a plurality of mobile portable units, each port having a transmitter for transmitting at an assigned downlink frequency to at least one portable unit, a receiver for receiving at an associated uplink frequency from said at least one portable unit and for receiving at all the downlink frequencies being transmitted at by the other of the plurality of ports in the system, and means for measuring the power level of signals received at all the possible different downlink frequencies from the other of the plurality of ports in the system, comprising the steps of:

(a) turning off the transmitter at a first port;

(b) tuning the receiver at that first port to each possible downlink frequency;

(c) measuring at that first port the power level of the downlink signals received at each of the possible downlink frequencies from the other of the plurality of ports in the system;

(d) determining at that first port the downlink frequency associated with the lowest measured power level;

(e) assigning and setting the downlink frequency at that first port to the downlink frequency determined in step (d);

(f) turning on the transmitter at that first port with its transmitting downlink frequency being set at the frequency set in step (e);

(g) repeating steps (a) through (f) at each of the other of the plurality of ports in the system; and

(h) after each of the plurality of ports in the system has its downlink frequency set in accordance with steps (a) through (f), repeating steps (a) through (g) to update the assignment of downlink frequencies to each of the ports.

7. A method in accordance with claim 6 wherein in step (h) each port independently waits a random time before repeating steps (a) through (f).

8. A method in accordance with claim 6 wherein step (h) repeats steps (a) through (f) at each port a predetermined number of times.

9. A method in accordance with claim 6 wherein a signal generated by a central controller initiates the start of steps (a) through (f) at each port.

10. A method in accordance with claim 6 wherein step (h) repeats steps (a) through (g) until no port sets its downlink frequency to a new downlink frequency in two consecutive repeats of steps (a) through (g).

11. In a frequency-reusing radio communications system having a plurality of fixed ports and a plurality of mobile portable units, each one of the plurality of the ports having a transmitter for transmitting to at least one portable unit at an assigned downlink frequency and a receiver for receiving from said at least one portable unit at an associated uplink frequency and for receiving at all the downlink frequencies being transmitted by the other of the plurality of ports in the system, each one of the plurality of ports further comprising means for setting the downlink and associated uplink frequencies comprising:

means for turning the transmitter off for setting the downlink and uplink frequencies and for turning the transmitter on for transmitting to at least one portable unit at the set downlink frequency;

means for measuring the power level of the downlink signals received at each of the possible downlink frequencies from the other of the plurality of ports in the system when said transmitter is off;

means for determining the downlink frequency associated with the lowest measured power level; and

means for setting as the downlink frequency of the transmitter to the downlink frequency determined to be associated with the lowest measured power level and for setting as the uplink frequency of the receiver to the frequency associated with that set downlink frequency.

12. A port in accordance with claim 11 further comprising control means for controlling when the downlink and uplink frequencies are set.

13. A port in accordance with claim 12 wherein said control means sets and resets the downlink and uplink frequencies at randomly spaced times.

14. A system in accordance with claim 13 wherein said control means iteratively sets the downlink and uplink frequencies a predetermined number of times.

15. A system in accordance with claim 11 wherein each of the plurality of ports is connected to a centralized control means, said centralized control means for controlling when each of the plurality of ports sets its downlink and uplink frequencies.

16. A system in accordance with claim 15 wherein said centralized control means sequentially initiates the setting of the downlink and uplink frequencies at each of the plurality of ports.

17. A system in accordance with claim 16 wherein said centralized control means iteratively sets the downlink and uplink frequencies of each of the plurality of ports until no port changes its frequency assignment in two consecutive iterations.