Methods and apparatus for transmitting information between a basestation and multiple mobile stations

• US 6,694,147 B1
• Filed: 10/18/2000
• Issued: 02/17/2004
• Est. Priority Date: 09/15/2000
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Flarion Technologies Inc (Qualcomm, Inc.)
• Inventors: Laroia, Rajiv, Viswanath, Pramod, Tse, David N. C.
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): D AGOSTA, STEPHEN M
• Application Number:
  US09/691,766
• Time in Patent Office: 1,217 Days
• Field of Search: 455/517, 455/436, 455/439, 455/445, 455/513, 455/524, 455/525, 370/318, 370/329, 370/330, 370/332, 370/333, 370/334, 370/468
• US Class Current: 455/517
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• CPC Class Codes: H04B 7/0671 using different delays between antennas
• CPC Class Codes: H04B 7/0682 using phase diversity (e.g. phase sweeping)
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04W 28/22 Negotiating communication rate
• CPC Class Codes: H04W 52/267 taking into account the information rate
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

Methods and apparatus for scheduling mobile stations (MSs) to download data and/or to control the rate of downloading to an MS from a base station (BS) as a function of downlink channel condition information are described. Artificial channel variations, which can be measured at the MS, and feedback to a BS for scheduling purposes, are introduced through the use of two or more transmitter antennas at a BS. Each of the antennas transmits a signal at the same frequency having the same information content, e.g., modulated data. However the signals are made to differ with time in their phase and/or amplitude to introduce what appear to be channel variations to the MSs.

Claims

1. A communications method for use in a communications system including a first device, a second device, and a third device, the method comprising the steps of:

operating the first device to receive first communications channel condition information regarding the condition of a first communications channel existing between the first device and the second device and to receive second communications channel condition information regarding the condition of a second communications channel existing between the first device and the third device;

determining, as a function of the first communications channel condition information, when to transmit data from the first device to said second device; and

determining, as a function of the second communications channel condition information, when to transmit data to said third device;

transmitting, using a plurality of N antennas, the same data to the second device, N being a positive integer greater than one, the step of transmitting including;

transmitting from a first antenna in said plurality of N antennas a first data signal including said data;

transmitting from a second antenna in said plurality of N antennas a second data signal including the same data as said first data signal; and

varying the relative amplitudes of the first and second data signals as a function of time while maintaining the combined average transmitted power of the first and second data signals at an almost constant value over the period in time during which the relative amplitudes of the first and second data signals are varied.

2. The communications method of claim 1, further comprising the step of:

determining the rate at which to transmit data to the first device as a function of the first communications channel condition information.

3. The communications method of claim 2, further comprising the step of:

allocating bandwidth as a function of the determined data transmission rate.

4. The communications method of claim 2, further comprising the step of:

controlling the amount of power used to transmit data from the first device to the second device as a function of the determined data transmission rate.

5. The communications method of claim 2, further comprising:

using a first amount of power to transmit data from the first device to the second device when the determined data transmission rate is a first rate; and

using a second amount of power to transmit data from the first device to the second device, which is greater than the first amount of power, when the determined data transmission rate is a second rate which is greater than the first rate.

6. The communications method of claim 3, wherein the step of allocating bandwidth includes:

allocating a first amount of bandwidth when the determined data transmission rate is a first rate; and

allocating a second amount of bandwidth which is greater than the first amount when the determined data transmission rate is a second rate which is greater than the first rate.

7. The method of claim 1, further comprising the step of:

operating the second device to measure the amplitude of a first signal received from the first device; and

transmitting first signal amplitude information from the second device to the first device, said first communications channel condition information including said first signal amplitude information.

8. The method of claim 7, further comprising the step of:

operating the third device to measure the amplitude of a second signal received from the first device; and

transmitting second signal amplitude information from the third device to the first device, said second communications channel condition information including said second signal amplitude information.

9. The method of claim 8, wherein the first device is a base station, and the second and third devices are mobile stations.

10. The method of claim 1, wherein the step of determining when to transmit includes the step of:

scheduling data transmissions to said second and third devices such that the devices associated with better channel conditions are given scheduling preference over devices associated with poorer channel conditions.

11. The method of claim 1, further comprising the step of:

varying the phase of at least one of the first and second data signals being transmitted as a function of time.

12. The method of claim 11, wherein the first and second data signals have the same carrier frequency, fc.

13. The method of claim 12, further comprising the step of spacing the first and second antennas at least one half a wavelength apart, wherein the wavelength is equal to C divided by fc, where C is the speed of light.

14. The method of claim 1, wherein the first and second data signals have the same carrier frequency, fc.

16. The method of claim 1, wherein N is greater than two.

15. A communications method for use in a communications system including a first device, a second device, and a third device, the method comprising the steps of:

operating the first device to receive first communications channel condition information regarding the condition of a first communications channel existing between the first device and the second device and to receive second communications channel condition information regarding the condition of a second communications channel existing between the first device and the third device; and

determining, as a function of the first communications channel condition information, when to transmit data from the first device to said second device; and

determining, as a function of the second communications channel condition information, when to transmit data to said third device;

transmitting, using a plurality of N antennas, the same data to the second device, N being a positive integer greater than one, the step of transmitting including;

transmitting from a first antenna in said plurality of N antennas a first data signal including said data;

transmitting from a second antenna in said plurality of N antennas a second data signal including the same data as said first data signal, the first and second data signals including symbols having a symbol period; and

varying at least one of the relative amplitudes of the first and second data signals over time and the relative phase of the first and second data signals over time while using a fixed average amount of power over at least one symbol period to transmit the combination of the first and second data signals.