IP Library › Granted Patent US 9,456,428
Granted Patent B2
US 9,456,428 · App. 14/189,520 · Granted Sep 27, 2016

Method and apparatus for allowing soft handoff of a CDMA reverse link utilizing an orthogonal channel structure

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Quick Facts
Patent No.
US 9,456,428
App. No.
14/189,520
Granted
Sep 27, 2016
Kind
B2
Abstract

Method and apparatus for base stations and subscriber units allows soft handoff of a CDMA reverse link utilizing an orthogonal channel structure. Subscriber units transmit an orthogonally coded signal over a reverse link to the base stations. A given base station provides timing control of the timing offset of the reverse link signal. Based on at least one criterion, an alignment controller determines that the given base station should hand off timing control to another base station, and a soft handoff process ensues. In response to a command or message for soft handoff of the subscriber unit from the given base station to another base station, the subscriber unit makes a coarse timing adjustment to the timing of the coded signal. The subscriber unit may make fine timing adjustments based on feedback from the base station controlling timing. Multiple base stations may provide power control feedback to the subscriber unit.

Claims (41)

1. An integrated circuit (IC) for use in a wireless subscriber unit comprising:

circuitry configured to output packet data for transmission in soft handover to a plurality of base stations; wherein the packet data is transmitted using at least one orthogonal code and a pseudo noise (PN) code;

wherein the circuitry is further configured to receive as an input a power control command from each of at least two of the base stations;

wherein the circuitry is further configured in response to the received power control commands, to output an adjustment to adjust a power level associated with the transmission of the packet data;

wherein the power level is a lowest power level indicated by one of the power control commands; and

the circuitry is further configured to receive power commands sent from the base stations including a multiple bit power command indicating a plurality of power levels and a signal bit power command indicating at least a power down.

2. An integrated circuit (IC) for use in a wireless subscriber unit comprising:

circuitry configured to output packet data for transmission in soft handover to two base stations;

wherein the packet data is transmitted using at least one orthogonal code and a pseudo noise (PN) code;

wherein the circuitry is further configured to receive as an input a power control command from each of the base stations;

wherein the circuitry is further configured in response to the received power control commands, to output an adjustment to adjust a power level associated with the transmission of the packet data;

wherein the power level is a lowest power level indicated by one of the power control commands; and

the circuitry is further configured to receive power commands sent from the base stations including a multiple-bit power command indicating a plurality of power levels and a signal bit power command indicating at least a power down.

3. A wireless subscriber unit for use in a wireless communication system, the wireless subscriber unit comprising:

a receiver configured to receive, from a first base station, a first absolute timing adjustment followed by a first plurality of relative timing adjustments;

a transmitter configured to transmit at least a first reverse link signal derived from a pseudo noise (PN) sequence and an orthogonal sequence with a timing derived from the first absolute timing adjustment and the first plurality of relative timing adjustments;

the wireless subscriber unit further configured to initiate handover to a second base station;

the receiver further configured, in response to the handover, to receive a second absolute timing adjustment from the second base station;

the wireless subscriber unit further configured to adjust a reverse link timing in response to the received second absolute timing adjustment;

the receiver further configured to receive a second plurality of relative timing adjustments from the second base station; and

the transmitter further configured to transmit at least a second reverse link signal derived from a PN sequence and an orthogonal sequence with a timing derived from the second absolute timing adjustment and the second plurality of relative timing adjustments.

4. The wireless subscriber unit of claim 3 further comprising:

the transmitter configured to transmit packet data in soft handover to the first base station and the second base station.

5. The wireless subscriber unit of claim 3 further comprising:

the receiver configured to receive at least a first power control command from the first base station.

6. The wireless subscriber unit of claim 3 further comprising:

the receiver configured to receive at least a second power control command from the second base station.

7. A method for use by a wireless subscriber unit in a wireless communication system, the method comprising:

receiving, at the wireless subscriber unit from a first base station, a first absolute timing adjustment followed by a first plurality of relative timing adjustments;

transmitting, by the wireless subscriber unit, at least a first reverse link signal derived from a pseudo noise (PN) sequence and an orthogonal sequence with a timing derived from the first absolute timing adjustment and the first plurality of relative timing adjustments;

initiating, by the wireless subscriber unit, handover to a second base station;

in response to the handover, receiving, at the wireless subscriber unit, a second absolute timing adjustment from the second base station;

adjusting, by the wireless subscriber unit, a reverse link timing in response to the received second absolute timing adjustment;

receiving, at the wireless subscriber unit, a second plurality of relative timing adjustments from the second base station; and

transmitting, by the wireless subscriber unit, at least a second reverse link signal derived from a PN sequence and an orthogonal sequence with a timing derived from the second absolute timing adjustment and the second plurality of relative timing adjustments.

8. The method of claim 7 further comprising:

transmitting, by the wireless subscriber unit, packet data in soft handover to the first base station and the second base station.

9. The method of claim 7 further comprising:

receiving, at the wireless subscriber unit, at least a first power control command from the first base station.

10. The method of claim 7 further comprising:

receiving, at the wireless subscriber unit, at least a second power control command from the second base station.