Beacon detection method and apparatus for sharing spectrum between wireless communications systems and fixed microwave systems

• US 5,412,658 A
• Filed: 10/22/1993
• Issued: 05/02/1995
• Est. Priority Date: 10/22/1993
• Status: Expired due to Term

• Current Assignee: Intellectual Ventures II LLC (Intellectual Ventures LLC)
• Original Assignee: Bell Communications Research, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Devasirvathan, Daniel M., Sutliff, Larrie G., Sollenberger, Nelson R., Varma, Vijay K., Arnold, Hamilton W.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Jung, Min
• Application Number:
  US08/142,553
• Time in Patent Office: 557 Days
• Field of Search: 370/95.1, 370/95.3, 370/69.1, 455/33.1, 455/33.3, 455/33.4, 455/34.1, 455/37.1, 455/56.1, 455/62, 455/63, 455/67.1, 455/67.3, 455/67.5, 379/59
• US Class Current: 370/330
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks

Abstract

A system for spectrum sharing between a point-to-point microwave system and a TDM/TDMA wireless communications system in a common geographical area is described. Each transmitter/receiver in the point-to-point microwave system transmits, in addition to its normal information signal, a beacon signal which is uniquely associated with the receiver receive frequency. In selecting uplink and downlink frequencies for port assignment, each port monitors the beacon frequencies and selects as uplink and downlink frequencies, frequencies which associated beacons fall below a predetermined threshold. Similarly, before accessing the wireless communications system through a selected port, a portable monitors the beacons associated with the selected port'"'"'s uplink frequency. If the beacon associated with the uplink frequency exceeds a threshold, the portable selects an alternate port through which to access the network. Also, during a call an emergency link transfer to another port is made if the monitored beacon corresponding to the portable'"'"'s uplink frequency rises above the threshold.

Claims

1. In a geographical area commonly comprising:

a plurality of point-to-point microwave transmitter/receivers transmitting and receiving information signals at fixed frequencies within a predetermined spectrum to associated transmitter/receivers, each transmitter/receiver also transmitting a beacon within said predetermined spectrum that is uniquely identified in frequency with its associated transmitter/receiver receive frequency; and

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 within said predetermined spectrum to at least one mobile transceiver and a receiver for receiving at an associated uplink frequency within said predetermined spectrum from at least one mobile transceiver and for receiving signals transmitted by other sources within said predetermined spectrum, each mobile transceiver having a transmitter for transmitting signals at any one of a plurality of uplink frequencies to any one of said plurality of fixed base units and a receiver for receiving signals at any one of a plurality of associated downlink frequencies from any one of said plurality of fixed base units and for receiving signals transmitted by other sources within said predetermined spectrum, wherein at least some of the point-to-point microwave transmitter/receivers transmit and receive at at least some of the same frequencies used as downlink and uplink frequencies of the frequency-reusing radio communications system, a method of assigning frequencies to at least one fixed base unit in the frequency-reusing radio communications system to prevent a transmission from said at least one fixed base unit or from a mobile transceiver communicating with said at least one fixed base unit from interfering with the information signals received at any point-to-point receiver in the common geographical area, comprising the steps of;

(a) at said at least one fixed base unit, selecting a frequency for downlink transmission based on a signal quality criteria;

(b) monitoring at said at least one base unit a received beacon corresponding to the frequency selected for downlink transmission;

(c) determining whether the received beacon is above or below a predetermined threshold;

(d) if the received beacon is above the predetermined threshold, selecting another frequency for downlink transmission by said at least one base unit that is acceptable from a signal quality standpoint and repeating steps (b) and (c) for the selected another downlink frequency;

(e) if the received beacon is below the predetermined threshold, monitoring at said at least one fixed base unit a second received beacon that corresponds to the uplink frequency associated with the downlink frequency selected in step (a) or the another downlink frequency selected in step (d);

(f) determining whether the second received beacon corresponding to the uplink frequency is above or below the predetermined threshold;

(g) if the second received beacon corresponding to the uplink frequency is above the predetermined threshold, selecting another frequency for downlink transmission by the first base unit that is acceptable from a signal quality standpoint and repeating steps (b), (c), (d), (e) and (f) for this selected another downlink frequency; and

(h) if the second received beacon corresponding to the uplink frequency is below the predetermined threshold, assigning and setting the downlink frequency of the at least one fixed base unit to the selected frequency which corresponding beacon is below the predetermined threshold.

2. A method in accordance with claim 1 further comprising the step of repeating steps (a) through (h) at each of the plurality of base units in the frequency-reusing radio communications system.

3. In a geographical area commonly comprising:

a plurality of point-to-point microwave transmitter/receivers transmitting and receiving information signals at fixed frequencies within a predetermined spectrum to associated transmitter/receivers, each transmitter/receiver also transmitting a beacon within said predetermined spectrum that is uniquely identified in frequency with its associated transmitter/receiver receive frequency; and

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 within said predetermined spectrum to at least one mobile transceiver and a receiver for receiving at an associated uplink frequency within said predetermined spectrum from at least one mobile transceiver and for receiving signals transmitted by other sources within said predetermined spectrum, each mobile transceiver having a transmitter for transmitting signals at any one of a plurality of uplink frequencies to any one of said plurality of fixed base units and a receiver for receiving signals at any one of a plurality of associated downlink frequencies from any one of said plurality of fixed base units and for receiving signals transmitted by other sources within said predetermined spectrum, wherein at least some of the point-to-point microwave transmitter/receivers transmit and receive at at least some of the same frequencies used as downlink and uplink frequencies of the frequency-reusing radio communications system, a method by a mobile transceiver of selecting a fixed base unit through which to access the frequency-resuing radio communications system to prevent a transmission from the mobile transceiver from interfering with the information signals received at any point-to-point receiver in the common geographic area, comprising the steps of;

(a) at the mobile transceiver selecting a fixed base unit through which to access the frequency-reusing radio communications system based on a signal quality criteria;

(b) monitoring at the mobile transceiver a received beacon corresponding to the uplink frequency of the selected fixed base unit;

(c) determining whether the received beacon is above or below a predetermined threshold;

(d) if the received beacon is above the predetermined threshold, selecting another fixed base unit for the mobile transceiver to access the frequency-reusing radio communications system that is acceptable from a signal quality standpoint, and repeating steps (b) and (c) for the selected another fixed base unit; and

(e) if the beacon is below the predetermined threshold, setting up a communications link between the mobile transceiver and the selected fixed base unit.

4. A method in accordance with claim 3 further comprising the steps of:

(f) after the communications link is set up between the mobile transceiver and the selected fixed base unit, periodically monitoring at the mobile transceiver the beacon corresponding to the uplink frequency of the selected fixed base unit;

(g) determining whether the beacon is above or below the predetermined threshold;

(h) if the beacon is below the predetermined threshold, maintaining the communications link between the mobile transceiver and the selected fixed base unit; and

(i) if the beacon is above the predetermined threshold, performing an emergency link transfer and selecting another fixed base unit through which to access the frequency-reusing radio communications system based on a signal quality criteria and repeating steps (b) through (e) for the newly selected another fixed base unit.

5. In a geographical area commonly comprising:

a plurality of point-to-point microwave transmitter/receivers transmitting and receiving information signals at fixed frequencies within a predetermined spectrum to associated transmitter/receivers, each transmitter/receiver also transmitting a beacon within said predetermined spectrum that is uniquely identified in frequency with its associated transmitter/receiver receive frequency; and

a TDM/TMDA wireless communications 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 within said predetermined spectrum to at least one portable unit and a receiver for receiving at an associated uplink frequency within said predetermined spectrum from at least one portable unit and for receiving signals transmitted by other sources within said predetermined spectrum, each portable unit having a transmitter for transmitting signals at any one of a plurality of uplink frequencies to any one of said plurality of ports and a receiver for receiving signals at any one of a plurality of associated downlink frequencies from any one of said plurality of ports and for receiving signals transmitted by other sources within said predetermined spectrum, wherein at least some of the point-to-point microwave transmitter/receivers transmit and receive at at least some of the same frequencies used as downlink and uplink frequencies of the TDM/TDMA wireless communications system, a method of assigning frequencies to at least one port in the TDM/TDMA wireless communications system to prevent a transmission from the said at least one port or from a portable unit communicating with said at least one port from interfering with the information signals received at any point-to-point receiver in the common geographical area, comprising the steps of;

(a) at said at least one port, selecting a frequency for downlink transmission based on a signal quality criteria;

(b) monitoring at said at least one port the received beacon corresponding to the frequency selected for downlink transmission;

(c) determining whether the received beacon is above or below a predetermined threshold;

(d) if the beacon is above the predetermined threshold, selecting another frequency for downlink transmission by said at least one port that is acceptable from a signal quality standpoint and repeating steps (b) and (c) for the selected another downlink frequency;

(e) if the beacon is below the predetermined threshold, monitoring at said at least one port a received second beacon that corresponds to the uplink frequency associated with the downlink frequency selected in step (a) or the another downlink frequency selected in step (d);

transmission;

(f) determining whether the received second beacon corresponding to the uplink frequency is above or below the predetermined threshold;

(g) if the second beacon corresponding to the uplink frequency is above the predetermined threshold, selecting another frequency for downlink transmission by the first port that is acceptable from a signal quality standpoint and repeating steps (b), (c), (d), (e) and (f) for this selected another downlink frequency; and

(h) if the second beacon corresponding to the uplink frequency is below the predetermined threshold, assigning and setting the downlink frequency of the at least one port to the selected frequency which corresponding beacon is below the predetermined threshold.

6. A method in accordance with claim 5 further comprising the step of repeating steps (a) through (h) at each of the plurality of ports in the TDM/TDMA wireless communications system.

7. In a geographical area commonly comprising:

a plurality of point-to-point microwave transmitter/receivers transmitting and receiving information signals at fixed frequencies within a predetermined spectrum to associated transmitter/receivers, each transmitter/receiver also transmitting a beacon within said predetermined spectrum that is uniquely identified in frequency with its associated transmitter/receiver receive frequency; and

a TDM/TDMA wireless communications 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 within said predetermined spectrum to at least one portable unit and a receiver for receiving at an associated uplink frequency within said predetermined spectrum from at least one portable unit and for receiving signals transmitted by other sources within said predetermined spectrum, each mobile portable unit having a transmitter for transmitting signals at any one of a plurality of uplink frequencies to any one of said plurality of ports and a receiver for receiving signals at any one of a plurality of associated downlink frequencies from any one of said plurality of ports and for receiving signals transmitted by other sources within said predetermined spectrum, wherein at least some of the point-to-point microwave transmitter/receivers transmit and receive at at least some of the same frequencies used as downlink and uplink frequencies of the TDM/TDMA wireless communications system, a method by a portable of selecting a port unit through which to access the TDM/TDMA wireless communications system to prevent a transmission from the portable unit from interfering with the information signals received at any point-to-point receiver in the common geographical area, comprising the steps of;

(a) at the portable unit selecting a port through which to access the TDM/TDMA wireless communications system based on a signal quality criteria;

(b) monitoring at the portable unit a received beacon corresponding to the uplink frequency of the selected port;

(c) determining whether the received beacon is above or below a predetermined threshold;

(d) if the beacon is above the predetermined threshold, selecting another port for the portable unit to access the TDM/TDMA wireless communications system that is acceptable from a signal quality standpoint, and repeating steps (b) and (c) for the selected another port; and

(e) if the beacon is below the predetermined threshold, setting up a communications link between the portable unit and the selected port.

8. A method in accordance with claim 7 further comprising the steps of:

(f) after the communications link is set up between the portable unit and the selected port, periodically monitoring at the portable unit the beacon corresponding to the uplink frequency of the selected port;

(g) determining whether the beacon is above or below the predetermined threshold;

(h) if the beacon is below the predetermined threshold, maintaining the communications link between the portable unit and the selected port;

(i) if the beacon is above the predetermined threshold, performing an emergency link transfer and selecting another port through which to access the TDM/TDMA wireless communications system based on a signal quality criteria, and repeating steps (b) through (e) for the newly selected another port.

9. In a TDM/TDMA wireless communications 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 within a predetermined spectrum to at least one portable unit and a receiver for receiving at an associated uplink frequency within said predetermined spectrum from at least one portable unit and for receiving signals transmitted by other sources within said predetermined spectrum, each portable unit having a transmitter for transmitting signals at any one of a plurality of uplink frequencies to any one of said plurality of ports and a receiver for receiving signals at any one of a plurality of associated downlink frequencies from any one of said plurality of ports and for receiving signals transmitted by other sources within said predetermined spectrum, the ports and portables in the TDM/TDMA wireless communications system be located in the same geographical area with a point-to-point microwave transmission system having a plurality of point-to-point microwave transmitter/receivers transmitting and receiving information signals at fixed frequencies within the same predetermined spectrum and at at least some of the same frequencies as said uplink and downlink frequencies, each transmitter/receiver also transmitting a beacon within said predetermined spectrum that is uniquely identified in frequency with its associated transmitter/receiver receive frequency, each one of the ports further comprising means for setting the downlink and associated uplink frequencies, said means for setting comprising means for determining whether a transmission by a port at a selected downlink frequency or by a portable at its associated selected uplink frequency will cause interference with signals received by a transmitter/receiver in the point-to-point microwave system, said means for determining comprising:

means for tuning the receiver in the port to receive the beacon signals corresponding to selected downlink and uplink frequencies;

means for measuring the power of the received beacons corresponding to the selected downlink and uplink frequencies;

comparing means for comparing the power of the received beacons with a predetermined threshold; and

means for selecting an alternative downlink and associated uplink frequency if the power of the either of the beacons corresponding to a selected downlink or associated uplink frequency are greater than said predetermined threshold.

10. A port in accordance with claim 9 further comprising filtering means for narrowband filtering the received beacon signals.

11. In a TDM/TDMA wireless communications 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 within a predetermined spectrum to at least one portable unit and a receiver for receiving at an associated uplink frequency within said predetermined spectrum from at least one portable unit and for receiving signals transmitted by other sources within said predetermined spectrum, each portable unit having a transmitter for transmitting signals at any one of a plurality of uplink frequencies to any one of said plurality of ports and a receiver for receiving signals at any one of a plurality of associated downlink frequencies from any one of said plurality of ports and for receiving signals transmitted by other sources within said predetermined spectrum, the ports and portables in the TDM/TDMA wireless communications system be located in the same geographical area with a point-to-point microwave transmission system having a plurality of point-to-point microwave transmitter/receivers transmitting and receiving information signals at fixed frequencies within the same predetermined spectrum and at at least some of the same frequencies as said uplink and downlink frequencies, each transmitter/receiver also transmitting a beacon within said predetermined spectrum that is uniquely identified in frequency with its associated transmitter/receiver receive frequency, each one of the portables further comprising accessing means for selecting a port with which to access the network based on a signal quality measure;

said means for accessing comprising means for determining whether a transmission by a portable on an uplink frequency of a selected port will cause interference with signals received by a transmitter/receiver in the point-to-point microwave system, said means for determining comprising;

means for tuning the receiver in the portable to receive the beacon signal corresponding to the uplink frequency of tile selected port;

means for measuring the power of the received beacon corresponding to the uplink frequency of the selected port;

comparing means for comparing the power of the received beacon with a predetermined threshold; and

means for selecting an alternative port with which to access the network if the power of the the received beacon corresponding to the uplink frequency of the selected port is greater than said predetermined threshold.

12. A portable in accordance with claim 11 wherein said means for tuning periodically monitors the beacon signal corresponding to the uplink frequency of the selected port during access to the port by the portable, and said means for selecting selects an alternative port with which to access the network if during a monitoring period the power of the received beacon corresponding to the uplink frequency of the selected port is greater than said predetermined threshold.

13. A portable in accordance with claim 11 further comprising filtering means for narrowband filtering the received beacon signals.