Spatially randomized pilot symbol transmission methods, systems and devices for multiple input/multiple output (MIMO) wireless communications

Patent metadata

Field	Value
Publication number	US-9036684-B2
Application number	US-201113247597-A
Country	US
Kind code	B2
Filing date	Sep 28, 2011
Priority date	Sep 28, 2011
Publication date	May 19, 2015
Grant date	May 19, 2015

Abstract

Compressive sampling is used to generate pilot symbols to be transmitted over an array of antennas in a MIMO wireless communications device. A pilot symbol is transmitted over the array of antennas according to a spatially randomized antenna transmission function that randomly changes across the array of antennas. The randomized antenna transmission function may randomly select/deselect antennas and/or randomly change amplitude and/or phase of the pilot symbol transmission. Channel estimates can be constructed at a receiver based on the spatially randomized pilot symbols that were transmitted.

First claim

What is claimed is:

1. A method of transmitting pilot symbols by a multiple input multiple output (MIMO) wireless communications device that includes an array of antennas, the method comprising:
obtaining a predetermined pseudo-random number sequence; and
transmitting a pilot symbol in a sequence of pilot symbols simultaneously over the array of antennas according to a random antenna transmission function that randomly changes across the array of antennas based on the predetermined pseudo-random number sequence.

2. The method according to claim 1 wherein the transmitting comprises:
transmitting the pilot symbol in the sequence of pilot symbols simultaneously over the array of antennas at a given frequency and/or at a given time slot according to the randomly changing antenna transmission function.

3. The method according to claim 1 further comprising constructing a channel estimate from the pilot symbols that are received in a radio signal over a MIMO wireless communications channel, the method of constructing a channel estimate comprising:
obtaining sets of random weights;
receiving, at one or more antennas, the radio signal at designated frequencies and/or times over which the pilot symbols were transmitted over the MIMO wireless communications channel;
determining channel model parameters that match the radio signal that was received at the designated frequencies and/or times over which the pilot symbols were transmitted over the MIMO wireless communications channel, based on the sets of random weights that are obtained, and
constructing the channel estimate based on the channel model parameters that were determined.

4. The method according to claim 3 wherein the sets of random weights comprise sets of predetermined pseudo-random weights.

5. The method according to claim 3 wherein the determining comprises:
generating a signal model matrix from a set of the random weights and at least one channel transformation matrix; and
computing channel model parameters from the radio signal that was received and the signal model matrix;
wherein the constructing comprises determining a channel estimate of the MIMO wireless communications channel from the channel model parameters and the at least one channel transformation matrix.

6. The method according to claim 3 wherein the determining comprises:
iteratively determining a signal model component and a corresponding channel model parameter that match a residual signal of the radio signal that was received, based on the set of the random weights and the radio signal that was received; and
computing an estimate of channel model parameters from the signal model component that was iteratively determined;
wherein the constructing comprises determining a channel estimate of the MIMO wireless communications channel from the channel model parameters and at least one channel transformation matrix.

7. A method of transmitting pilot symbols by a multiple input multiple output (MIMO) wireless communications device that includes an array of antennas, the method comprising:
transmitting a pilot symbol in a sequence of pilot symbols simultaneously over the array of antennas according to a random antenna transmission function that randomly changes across the array of antennas,
wherein the random antenna transmission function comprises a random antenna select/deselect function that causes the pilot symbol in the sequence of pilot symbols to be transmitted simultaneously over a randomly selected subset of the array of antennas, and
wherein the randomly selected subsets of the array of antennas range from one to all of the antennas.

8. A method of transmitting pilot symbols by a multiple input multiple output (MIMO) wireless communications device that includes an array of antennas, the method comprising:
transmitting a pilot symbol in a sequence of pilot symbols simultaneously over the array of antennas according to a random antenna transmission function that randomly changes across the array of antennas,
wherein the random antenna transmission function comprises a random antenna transmission amplitude function that causes the pilot symbol in the sequence of pilot symbols to be transmitted simultaneously over the array of antennas at an amplitude that randomly changes across the array of antennas and/or a random antenna transmission phase function that causes the pilot symbol to be transmitted simultaneously over the array of antennas at a phase that randomly changes across the array of antennas.

9. A method of transmitting pilot symbols by a multiple input multiple output (MIMO) wireless communications device that includes an array of antennas, the method comprising:
obtaining sets of random weights, wherein a respective random weight in a respective set of random weights is associated with a corresponding one of the antennas; and
transmitting a pilot symbol in a sequence of pilot symbols simultaneously over the array of antennas according to the respective set of random weights that was obtained.

10. The method according to claim 9 wherein the sets of random weights comprise sets of predetermined pseudo-random weights.

11. The method according to claim 9 wherein each random weight has either a first value that selects the corresponding antenna or a second value that deselects the corresponding antenna.

12. The method according to claim 9 wherein each random weight has either a first value that applies a first phase shift to the pilot symbol that is transmitted by the corresponding antenna or a second value that applies a second phase shift to the pilot symbol that is transmitted by the corresponding antenna.

13. The method according to claim 12 wherein each random weight has the first value that applies a first phase shift to the pilot symbol that is transmitted by the corresponding antenna, the second value that applies a second phase shift to the pilot symbol that is transmitted by the corresponding antenna, or a third value that deselects the corresponding antenna.

14. The method according to claim 9 wherein each random weight has one of a plurality of random values, which sets an amplitude value and/or phase value for the pilot symbol that is transmitted by the corresponding antenna.

15. The method according to claim 14 wherein the plurality of random values comprise a plurality of Gaussian-distributed complex symbols, each of which sets an amplitude and/or phase value for the pilot symbol that is transmitted by the corresponding antenna.

16. The method according to claim 14 wherein the plurality of random values comprise a plurality of unit-amplitude complex variables whose phase values are distributed in an interval from 0 to 2 times pi according to a predetermined probability distribution, each of which sets a phase value for the pilot symbol that is transmitted by the corresponding antenna.

17. The method according to claim 16 wherein the predetermined probability distribution is the uniform distribution.

18. A multiple input multiple output (MIMO) wireless communication node comprising:
an array of MIMO antennas;
a corresponding array of transmitters, a respective one of which is configured to transmit pilot symbols over a respective antenna of the array of MIMO antennas; and
a processor that is configured to:
obtain sets of random weights, wherein a respective random weight in a respective set of random weights is associated with a corresponding one of the antennas, and
provide a pilot symbol in a sequence of pilot symbols simultaneously to the array of transmitters for simultaneous tran

Assignees

• Hui Dennis
• Balachandran Kumar
• Cheng Jung-Fu
• Guey Jiann-Ching
• Ericsson Telefon Ab L M

Inventors

• Hui Dennis
• Balachandran Kumar
• Cheng Jung-Fu
• Guey Jiann-Ching

Classifications

• H04L5/0023

  Time-frequency-space · CPC title

• H04B7/0686

  Hybrid systems, i.e. switching and simultaneous transmission · CPC title

• H04B7/0615

  of weighted versions of same signal · CPC title

• H04L25/0226

  sounding signals per se · CPC title

• H04B7/0413 Primary

  MIMO systems · CPC title