System and method for reducing pilot signal contamination using orthogonal pilot signals

• US 10,554,264 B2
• Filed: 02/19/2019
• Issued: 02/04/2020
• Est. Priority Date: 07/23/2015
• Status: Active Grant

• Current Assignee: Nxgen Partners Ip, LLC (NxGen Partners LLC)
• Original Assignee: Nxgen Partners Ip, LLC (NxGen Partners LLC)
• Inventors: Ashrafi, Solyman
• Primary Examiner(s): Huang, David S
• Application Number:
  US16/278,784
• Publication Number:
  US 20190181924A1
• Time in Patent Office: 350 Days
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0057 Physical resource allocation for CQI
• CPC Class Codes: H04L 5/0062 Avoidance of ingress interference, e.g. ham radio channels

Abstract

A communications system includes a plurality of transmitting units that each generate a pilot signal modulated using quantum level overlay modulation to apply at least one orthogonal function to the pilot signal and transmit the modulated pilot signal from the transmitting unit over a pilot channel. A base station unit including a MIMO receiver for receiving the pilot signals over the pilot channels from the plurality of transmitting units, demodulating the modulated pilot signals using the quantum level overlay modulation to remove the at least one orthogonal function from the pilot signals and outputting the demodulated pilot signal. The at least one orthogonal function applied to the pilot signals are orthogonal to each other and substantially reduces pilot channel contamination between the pilot channels.

Claims

1. A communications system, comprising:

at least one first transmitting unit located in a first cell, each of the at least one first transmitting unit further comprising;

first signal processing circuitry for generating a first pilot signal at the first transmitting unit;

first QLO modulation circuitry for modulating the first pilot signal using quantum level overlay modulation to apply at least one first orthogonal function to the first pilot signal, wherein the modulated first pilot signal is mutually orthogonal in both time and frequency domains, further wherein the modulated first pilot signal minimizes time-frequency resources;

a first transceiver for transmitting the modulated first pilot signal from the at least one first transmitting unit over a first pilot channel from the first cell;

at least one second transmitting unit located in a second cell, each of the at least one second transmitting unit further comprising;

second signal processing circuitry for generating a second pilot signal at the second transmitting unit;

second QLO modulation circuitry for modulating the second pilot signal using the quantum level overlay modulation to apply at least one second orthogonal function to the second pilot signal, wherein the modulated second pilot signal is mutually orthogonal in both time and frequency domains, further wherein the modulated second pilot signal minimizes time-frequency resources;

a second transceiver for transmitting the modulated second pilot signal from the at least one second transmitting unit over a second pilot channel from the second cell; and

wherein the at least one first orthogonal function applied to the first pilot signal and the at least one second orthogonal function applied to the second pilot signal are orthogonal to each other and substantially reduces pilot channel contamination between the first pilot channel and the second pilot channel.

2. The communications system of claim 1 further comprising a receiving unit for receiving the first and second modulated pilot signals over the first and second pilot channels, demodulating the first and second modulated pilot signals using the quantum level overlay modulation to remove the at least one first and second orthogonal function from the first and second pilot signals and outputting the demodulated first and second pilot signals.

3. The communications system of claim 2, wherein the receiving unit further comprises a MIMO receiver including a plurality of antennas for receiving the modulated first and second pilot signals.

4. The communications system of claim 2, wherein the receiving unit further generates channel state information responsive to the demodulated first and second pilot signals.

5. The communications system of claim 1, wherein the modulation of the first and the second pilot signals provide new orthogonal basis sets to the first and second pilot signals.

6. The communications system of claim 1, wherein the at least one first and second orthogonal functions applied to the first and second pilot signals substantially reduce pilot channel contamination caused by hardware impairment due to in-band and out of band distortions and non-reciprocal transceivers due to internal clock structures.

7. The communications system of claim 1, wherein the at least one first and second orthogonal functions applied to the first and second pilot signals substantially reduces pilot channel contamination caused by frequency reuse between the first and second cells.

8. The communications system of claim 1, wherein the at least one first and second transceivers further transmit the modulated first and second pilot signals from the at least one first and second transceivers to a receiving unit over the first and second pilot channels using coordinated beamforming.

9. The communications system of claim 1, wherein the first and second signal processing circuitry generate the first and second pilot signals responsive to at least one of a time-multiplexed pilot scheme and a superimposed pilot scheme, further wherein the first and second pilot signals are transmitted in dedicated time slots in the time-multiplexed pilot scheme and the first and second pilot signals are superimposed with data and transmitted in all time slots in the superimposed pilot scheme.

10. A communications system, comprising:

a plurality of transmitting units, each transmitting unit generating a pilot signal modulated using quantum level overlay modulation to apply at least one orthogonal function to the pilot signal and transmitting the modulated pilot signal from the transmitting unit over a pilot channel;

a base station unit including a MIMO receiver for receiving the pilot signals over the pilot channels from the plurality of transmitting units, demodulating the modulated pilot signals using quantum level overlay demodulation to remove the at least one orthogonal function from the pilot signals and outputting the demodulated pilot signal;

wherein a number of pilot symbols on the pilot signal is greater than a number of antennas in the MIMO receiver; and

wherein each of the at least one orthogonal function applied to each of the pilot signals is orthogonal to each other and substantially reduces pilot channel contamination between the pilot channels.

11. The communications system of claim 10, wherein the modulated pilot signals are mutually orthogonal in both time and frequency domains, further wherein the modulated pilot signals minimize time-frequency resources.

12. The communications system of claim 10, wherein the MIMO receiver includes a plurality of antennas for receiving the modulated pilot signals.

13. The communications system of claim 10, wherein the base station unit further generates channel state information responsive to the demodulated pilot signals.

14. The communications system of claim 13, wherein the base station unit generates the channel state information using training based channel estimation based on known pilot signal sequences transmitted over the pilot channel, the known pilot signal sequences comprising at least one of a conventional time multiplexed pilot scheme sequence and a superimposed pilot scheme sequence.

15. The communications system of claim 14, wherein the base station unit implements at least one of flat fading and frequency selective MIMO training based channel estimation.

16. The communications system of claim 10, wherein the modulation of the pilot signals provide new orthogonal basis sets to the pilot signals.

17. The communications system of claim 10, wherein the at least one orthogonal function applied to the pilot signals substantially reduce pilot channel contamination caused by hardware impairment due to in-band and out of band distortions and non-reciprocal transceivers due to internal clock structures.

18. The communications system of claim 10, wherein the at least one orthogonal function applied to the pilot signals substantially reduces pilot channel contamination caused by frequency reuse between cells.

19. The communications system of claim 10, wherein the plurality of transmitting units further transmit the modulated pilot signals from the plurality of transmitting units to the base station unit over the pilot channels using coordinated beamforming.

20. The communications system of claim 10, wherein the plurality of transmitting units generate the pilot signals responsive to at least one of a time-multiplexed pilot scheme and a superimposed pilot scheme, further wherein the pilot signals are transmitted in dedicated time slots in the time-multiplexed pilot scheme and the pilot signals are superimposed with data and transmitted in all time slots in the superimposed pilot scheme.

21. The communications system of claim 10, wherein a minimum number of pilot symbols on the pilot signal equals a number of transmitting units.

22. The communications system of claim 10, wherein the at least one orthogonal function applied to the pilot signals substantially reduces pilot channel contamination caused by frequency reuse between cells within an asymptotic regime.