Method of handoff at the border between CDMA underlay and overlay systems
First Claim
1. A method at a mobile terminal, the mobile terminal being operative at a first carrier frequency with a base station in an area that overlays an underlay area comprising one or more base stations operating at an adjacent carrier frequency, the base station in the overlay area being in a first system that is operative in accordance with a first standard and the base stations in the underlay area being in a second system that is operative in accordance with a second standard different from the first, the method comprising:
- switching the mobile terminal from operation in accordance with the first standard at the first carrier to operation in accordance with the second standard at the adjacent carrier and redirecting it to a base station in the underlay area if both (1) the sum of measured power of a downlink signal received from the base station in the underlay area at the adjacent carrier plus, if it is transmitting, a present transmit power of an uplink signal being transmitted by the mobile terminal at the first carrier to the base station in the overlay area, is greater than a first predetermined threshold that indicates that the power received by the base station in the underlay area from the mobile terminal when the mobile terminal is transmitting an uplink signal at the first carrier can interfere with operation of a reverse link of that base station in the underlay area, and (2) if the difference between the measured power of the downlink signal received from the base station in the underlay area at the adjacent carrier and a measured power of a downlink signal received from the base station in the overlay area with which the mobile terminal is communicating at the first carrier is greater than a second predetermined threshold that indicates that the mobile terminal is near the border of the overlay area.
5 Assignments
0 Petitions
Accused Products
Abstract
To avoid interference with the reverse link of a base station within an underlay area, a described method determines when to redirect and handover a mobile terminal that is still communicating on an adjacent carrier with a border base station within an overlay area but is within the coverage area of the base station in the underlay area. The method determines that redirection and handover to the base station in the underlay area should occur when together: (1) the power being received on the downlink from the base station in the underlay area exceeds the power being received on the downlink from the border base station within the overlay area by a first predetermined threshold that indicates that the mobile terminal is at the border of the overlay area; and (2) the sum of the power being received on the downlink from the underlay base station plus the power of the signal being transmitted by the mobile terminal to the base station within the overlay area is greater than a second predetermined threshold that indicates that the power being received by the base station in the underlay area from the transmitting mobile terminal can interfere with the operation of that base station.
62 Citations
9 Claims
-
1. A method at a mobile terminal, the mobile terminal being operative at a first carrier frequency with a base station in an area that overlays an underlay area comprising one or more base stations operating at an adjacent carrier frequency, the base station in the overlay area being in a first system that is operative in accordance with a first standard and the base stations in the underlay area being in a second system that is operative in accordance with a second standard different from the first, the method comprising:
switching the mobile terminal from operation in accordance with the first standard at the first carrier to operation in accordance with the second standard at the adjacent carrier and redirecting it to a base station in the underlay area if both (1) the sum of measured power of a downlink signal received from the base station in the underlay area at the adjacent carrier plus, if it is transmitting, a present transmit power of an uplink signal being transmitted by the mobile terminal at the first carrier to the base station in the overlay area, is greater than a first predetermined threshold that indicates that the power received by the base station in the underlay area from the mobile terminal when the mobile terminal is transmitting an uplink signal at the first carrier can interfere with operation of a reverse link of that base station in the underlay area, and (2) if the difference between the measured power of the downlink signal received from the base station in the underlay area at the adjacent carrier and a measured power of a downlink signal received from the base station in the overlay area with which the mobile terminal is communicating at the first carrier is greater than a second predetermined threshold that indicates that the mobile terminal is near the border of the overlay area. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
9. A method at a base station, the base station being operative at a first carrier frequency with at least one mobile terminal, the base station being in an area that overlays an underlay area comprising one or more base stations operating at an adjacent carrier frequency, the base station in the overlay area being in a first system that is operative in accordance with a first standard and the base stations in the underlay area being in a second system that is operative in accordance with a second standard different than the first, the method comprising:
sending a redirection order to the mobile terminal to switch its operation in accordance with the first standard at the first carrier to operation in accordance with the second standard at the adjacent carrier and be redirected to the base station in the underlay area if both (1) of the sum of a received value of a power measured by the mobile terminal of a downlink signal being received from a base station in the underlay area at the adjacent carrier plus a received value of the power of the uplink signal being transmitted by the mobile terminal, is greater than a first predetermined threshold that indicates that the power being received by the base station in the underlay area from the mobile terminal when the mobile terminal is transmitting the uplink signal at the first carrier can interfere with operation of a reverse link of that base station in the underlay area, and (2) the difference between the received value of the measured power of the downlink signal being received from the base station in the underlay area at the adjacent carrier and a received value of the measured power of the downlink signal being received from the base station in the overlay area with which the mobile terminal is presently communicating at the first carrier is greater than a second predetermined threshold that indicates that the mobile terminal is near the border of the overlay area.
Specification