METHODS AND APPARATUS FOR TRANSMITTING INFORMATION BETWEEN A BASESTATION AND MULTIPLE MOBILE STATIONS

• US 20070111678A1
• Filed: 01/08/2007
• Published: 05/17/2007
• Est. Priority Date: 09/15/2000
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Laroia, Rajiv, Viswanath, Pramod, Tse, David
• Granted Patent: US 8,023,904 B2
• Time in Patent Office: Days
• US Class Current: 455/101
• 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 to 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. Multiple signals having the same transmission frequency and information content are received and interpreted as a single composite signal by a receiving MS.

Claims

1. A method of transmitting data between a first device and a second device, comprising the steps of:

providing a plurality of N separate antennas, said plurality including at least a first antenna and a second antenna, N being a positive integer greater than one;

operating the first device to transmit from the first antenna, a first signal including said data the first signal having a carrier frequency, fc, a broadcast region from the first antenna including the second device; and

operating the first device to transmit from the second antenna, a second signal including said data the second signal having the same carrier frequency, fc, as the first signal, a broadcast region from the second antenna including the second device, at least one of a phase and an amplitude of the second signal varying over time relative to the first signal, the combined average transmitted power of the first and second signals being maintained at an almost constant value over a period of time during which the at least one of a phase and an amplitude of the second signal is varied relative to the first signal.

2. The method of claim 1, wherein the phase of the second signal varies over time relative to the phase of the first signal, the method further comprising the step of:

introducing a variation into the phase of the second signal as a function of time prior to operating the second antenna to transmit the second signal.

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

controlling the rate at which data is transmitted as part of the first signal as a function of transmission channel quality information.

4. The method of claim 2, wherein the first device is a base station and the second device is a mobile station.

5. The method of claim 2, wherein the first device is a mobile station and the second device is a base station.

6. A method of transmitting data between a first device and a second device, comprising the steps of:

providing a plurality of N separate antennas, said plurality including at least a first antenna and a second antenna, N being a positive integer greater than one;

operating the first device to transmit from the first antenna, a first signal including said data the first signal having a center frequency, a broadcast region from the first antenna including the second device; and

operating the first device to transmit from the second antenna, a second signal including said data the second signal having the same center frequency as the first signal, a broadcast region from the second antenna including the second device, at least one of a phase and an amplitude of the second signal varying over time relative to the first signal, the combined average transmitted power of the first and second signals being maintained at an almost constant value over a period of time during which the at least one of a phase and an amplitude of the second signal is varied relative to the first signal.

7. The method of claim 6, further comprising the steps of:

introducing a variation into the phase of the second signal as a function of time prior to operating the second antenna to transmit the second signal; and

controlling the rate at which data is transmitted as part of the first signal as a function of transmission channel quality information.

8. A communications apparatus, comprising:

a source of data;

a transmitter circuit coupled to the source of data for generating a plurality of data signals each data signal including the same data, the plurality of data signals including a first data signal and a second data signal the first and second data signals differing from one another as a function of time by at least one of a phase and an amplitude; and

a plurality of antennas coupled to said transmitter circuit to receive and transmit said data signals in parallel, each antenna receiving and transmitting one of said data signals; and

means for 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.

9. The apparatus of claim 8, wherein the transmitter circuit includes means for independently varying the phase of at least one of the first and second data signals as a function of time.

10. The apparatus of claim 9, further comprising:

a receiver for receiving communications channel condition information; and

means for determining the rate at which data should be transmitted in said first and second data signals as a function of the communications channel information.

11. The apparatus of claim 9, further comprising:

a receiver for receiving communications channel condition information from a plurality of mobile stations regarding the condition of a communications channel associated with individual ones of said plurality of mobile stations; and

means for scheduling transmission of data to individual mobile stations as a function of the received communications channel condition information.

12. The apparatus of claim 11, wherein the means for scheduling includes a scheduling routine which gives preferential treatment to the scheduling of data transmissions to mobile stations with good communications channels as compared to mobile stations with poorer communications channels.

13. The apparatus of claim 11,

wherein the first and second data signals have the same center frequency, fc, and a wavelength W at the center frequency;

and

wherein the first and second antennas are spaced at least one half the distance of the wavelength W from each other.

14. The apparatus of claim 11,

wherein the first and second data signals have the same carrier frequency, fc and a wavelength W at the carrier frequency;

and

wherein the first and second antennas are spaced at least one half the distance of the wavelength W from each other.

15. The apparatus of claim 8,

wherein the first and second data signals have the same center frequency, fc and a wavelength W at the center frequency;

and

wherein the first and second antennas are spaced at least one half the distance of the wavelength W from each other.

16. The apparatus of claim 8,

wherein the first and second data signals have the same carrier frequency, fc and a wavelength W at the carrier frequency;

and

wherein the first and second antennas are spaced at least one half the distance of the wavelength W from each other.

17. The apparatus of claim 8, further comprising:

means for using a fixed amount of power to transmit the combination of the first and second data signals over time.

18. The apparatus of claim 17, wherein said transmitter circuit is an OFDM signal transmitter