Method and apparatus for forward power control in a communication system

• US 6,850,499 B2
• Filed: 01/05/2001
• Issued: 02/01/2005
• Est. Priority Date: 01/05/2001
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Wheatley, Charles E. III, Attar, Rashid A., Esteves, Eduardo A. S.
• Primary Examiner(s): Jung, Min
• Application Number:
  US09/755,654
• Publication Number:
  US 20020131376A1
• Time in Patent Office: 1,488 Days
• Field of Search: 370/317, 370/318, 370/328, 370/342, 455/522, 455/69, 455/67.11
• US Class Current: 370/328
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/26 using transmission rate or quality of service QoS [Quality of Service]
• CPC Class Codes: H04W 52/267 taking into account the information rate
• CPC Class Codes: H04W 52/286 during data packet transmission, e.g. high speed packet access [HSPA]
• CPC Class Codes: H04W 68/00 User notification, e.g. alerting and paging, for incoming communication, change of service or the like
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

In a data communication system capable of variable rate transmission, the data rate is determined by the largest C/I measurement of the forward link signals as measured at the Access Terminal. In one embodiment, the data transmission is scheduled based on an Access Terminal initiated forward power control, which reduces forward link rate quantization loss due to excess transmit power. The Access Terminal reports to the Access Point the excess C/I estimate for the selected rate. The Access Point then reduces its transmit power by an appropriate amount when serving that Access Terminal. In another embodiment, the data transmission is scheduled based on an Access Point initiated forward power control. The Access Point varies its transmit power over time either randomly or in synchronism with neighboring Access Points in the communication system, which enables an increase in the throughput achieved by users that receive a significant amount of interference.

Claims

1. A method for packet data transmission from at least one Access Point to an Access Terminal comprising:

paging an Access Terminal of a pending data transmission;

selecting an Access Point based on a set of parameters;

measuring an excess C/I of forward link signals from the selected Access Point;

sending the excess C/I measurement to said selected Access Point; and

transmitting data from said selected Access Point at a transmit power in accordance with said excess C/I measurement.

2. The method of claim 1, wherein said transmitting step is scheduled by a scheduler based on a priority of said Access Terminal.

3. The method of claim 1, wherein said measuring, selecting, and sending steps are performed at each time slot until said data transmission is completed.

4. The method of claim 1, wherein said transmitting step is performed using a directional beam.

5. The method of claim 1, wherein said data is transmitted to said Access Terminal in data packets.

6. The method of claim 5 further comprising:

transmitting a negative acknowledgment (NACK) messages for data packets not received by said Access Terminal.

7. The method of claim 5 further comprising:

retransmitting said data packets not received by said Access Terminal in accordance with said NACK messages.

8. The method of claim 5, wherein said data packets are of fixed size for all data rates.

9. The method of claim 5, wherein said data packets are transmitted over one or more time slots.

10. The method of claim 5, wherein each data packet comprises a preamble.

11. The method of claim 10, wherein a length of said preamble is based on said data rate.

12. The method of claim 1, wherein the excess C/I measurement is sent in a data request message.

13. A method for packet data transmission from at least one Access Point to an Access Terminal comprising:

paging an Access Terminal of a pending data transmission;

selecting an Access Point based on a set of parameters;

measuring an excess C/I of forward link signals from the selected Access Point;

sending a data request message including the excess C/I measurement to said selected Access Point; and

transmitting data from said selected Access Point at a data rate in accordance with said data request message and at a transmit power in accordance with said measured excess C/I measurement.

14. An Access Terminal, comprising:

a receiver for receiving paging messages on a forward link signal and performing a C/I measurements and excess C/I measurements on the forward link signal;

a controller coupled to said receiver for receiving said paging messages, C/I measurements and excess C/I measurements from the receiver, said controller selecting an Access Point; and

a transmitter coupled to said controller for transmitting data request messages including the C/I measurements and the excess C/I measurements.

15. An Access Point, comprising:

a receiver for receiving C/I measurements and excess C/I measurements;

a channel scheduler coupled to said receiver for receiving said C/I measurements and excess C/I measurements from the receiver, said channel scheduler selecting an Access Terminal for data transmission; and

a transmitter coupled to said channel scheduler for transmitting data at a transmit power based on the C/I measurements and excess C/I measurements.