Reference signal packing for wireless communications

• US 10,666,314 B2
• Filed: 02/24/2017
• Issued: 05/26/2020
• Est. Priority Date: 02/25/2016
• Status: Active Grant

• Current Assignee: Cohere Technologies Inc
• Original Assignee: Cohere Technologies Inc
• Inventors: Hadani, Ronny, Rakib, Shlomo Selim, Monk, Anton, Tsatsanis, Michail, Hebron, Yoav
• Primary Examiner(s): Lam, Kenneth T
• Application Number:
  US16/079,509
• Publication Number:
  US 20190379422A1
• Time in Patent Office: 1,187 Days
• CPC Class Codes: H04B 1/10 Means associated with receiver for limiting or suppressing noise or interference
• CPC Class Codes: H04B 1/46 by voice-frequency signals; by pilot signals
• CPC Class Codes: H04B 1/69 Spread spectrum techniques
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 2001/6912 using chirp
• CPC Class Codes: H04J 2011/0016 with FDM/FDMA and TDM/TDMA
• CPC Class Codes: H04L 12/28 characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks] wireless communication networks H04W ; arrangements for dividing the transmission path H04W40/00
• CPC Class Codes: H04L 27/2695 with channel estimation, e.g. determination of delay spread, derivative or peak tracking channel estimation H04L25/0202
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0026 Division using four or more dimensions
• CPC Class Codes: H04L 5/0035 Resource allocation in a cooperative multipoint environment
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04L 5/0094 Indication of how sub-channels of the path are allocated

Abstract

In a wireless communication network, pilot signals are transmitted over a wireless communication channel by determining a maximum delay spread for a transmission channel, determining a maximum Doppler frequency spread for the transmission channel, and allocating a set of transmission resources in a time-frequency domain to a number of pilot signals based on the maximum delay spread and the maximum Doppler frequency spread.

Claims

1. A wireless communication method, implemented by a wireless communication device, comprising:

determining a maximum delay spread for a transmission channel;

determining a maximum Doppler frequency spread for the transmission channel;

allocating, based on the maximum delay spread and the maximum Doppler frequency spread, a set of transmission resources in a time-frequency domain to a number of pilot signals in the time-frequency domain; and

transmitting the pilot signals over a wireless communication channel using transmission resources, wherein each of the pilot signals corresponds to a delta function in a delay-Doppler domain based on applying a symplectic transform to the pilot signals.

2. The method of claim 1, wherein the allocating the set of transmission resources includes:

staggering transmission resources for the number of pilot signals with respect to each other such that at least some of the pilot signals occupy transmission resources that do not occur on a rectangular grid in the delay-Doppler domain.

3. The method of claim 2, wherein the staggering includes staggering every other pilot signal.

4. The method of claim 1, wherein the set of transmission resources in the time-frequency domain occupied by any given pilot signal corresponds to a lattice comprising time instances uniformly distributed along a time axis and having a first step size and frequencies uniformly distributed along a frequency axis and having a second step size.

5. The method of claim 1, wherein the set of transmission resources in the time-frequency domain occupied by the pilot signal correspond to a lattice comprising time instances non-uniformly distributed along a time axis.

6. The method of claim 1, wherein the set of transmission resources in the time-frequency domain occupied by at least one pilot signal correspond to a lattice comprising frequencies that are non-uniformly distributed along a frequency axis.

7. The method of claim 1, wherein the set of transmission resources in the time-frequency domain occupied by at least one pilot signal is non-overlapping with another set of resources in the time-frequency domain over which user data is transmitted by the wireless communication device.

8. The method of claim 1, wherein the transmitting the pilot signal includes transmitting the pilot signal to a given user equipment prior to transmitting data to the user equipment.

9. The method of claim 1, wherein the generating the pilot signal includes:

scrambling a basis signal using a two-dimensional (2-D) chirp sequence.

10. The method of claim 1, wherein each pilot signal corresponds to a different cyclic shift in a time domain and/or a frequency domain of a root 2-D Zadoff-Chu sequence.

11. The method of claim 1, wherein the transmitting the pilot signal is performed continuously, regardless of data transmissions.

12. The method of claim 1, wherein the wireless communication device includes a base station, the method further including pre-coding data prior to data transmissions, and generating at least two pilot signals occupying two sets of transmission resources non-overlapping in the time-frequency domain.

13. The method of claim 12, further including:

individually transmitting the at least two pilot signals to two different user equipment at time instances that are non-overlapping with each other.

14. The method of claim 12, further including:

individually transmitting the at least two pilot signals from two different user equipment at time instances that are non-overlapping with each other.

15. The method of claim 12, wherein the at least two pilot signals use non-overlapping delay domain resources or non-overlapping Doppler domain resources.

16. The method of claim 1, wherein the wireless communication device includes a user equipment, and wherein the set of transmission resources are specified to the wireless communication device in a upper layer message.

17. A wireless communication method, implemented by a wireless communication device, comprising:

determining a maximum delay spread for a transmission channel;

determining a maximum Doppler frequency spread for the transmission channel;

determining, based on the maximum delay spread and the maximum Doppler frequency spread, a number of pilot signals in a time-frequency domain that can be transmitted using a set of two-dimensional transmission resources;

allocating the set of two-dimensional transmission resources to the number of pilot signals; and

allocating the set of two-dimensional transmission resources to the number of pilot signals; and

transmitting the pilot signals over a wireless communication channel using the set of two-dimensional transmission resources, wherein each of the pilot signals corresponds to a delta function in a delay-Doppler domain based on applying a symplectic transform to the pilot signals.

18. The method of claim 17, wherein the determining the number of pilot signals further includes determining the number of pilot signals based on one or more of a number of receivers to send the pilot signals to, a number of transmission layers used for transmissions to the receivers, a number of receivers that are also transmitting pilot signals, and possible interference from another cell'"'"'s pilot signals.

19. The method of claim 17, wherein the allocating the set of two-dimensional transmission resources to the number of pilot signals includes determining an observation window in the time-frequency domain for the pilot signals.

20. The method of claim 17, wherein the allocating the set of two-dimensional transmission resources includes:

staggering transmission resources for the number of pilot signals with respect to each other such that at least some of the pilot signals occupy transmission resources that do not occur on a rectangular grid in the delay-Doppler domain.

21. The method of claim 20, wherein the staggering is performed by shifting locations of staggered pilot signals from non-staggered pilot signals to maximize a distance in a dimension of the shift.

22. A wireless communication apparatus, comprising:

a memory storing instructions;

a processor; and

a transmitter communicatively coupled to the memory and the processor;

wherein the memory stores instructions for causing the processor to implement a method, comprising;

determining a maximum delay spread for a transmission channel;

determining a maximum Doppler frequency spread for the transmission channel;

allocating, based on the maximum delay spread and the maximum Doppler frequency spread, a set of transmission resources in a time-frequency domain to a number of pilot signals in the time-frequency domain; and

transmitting the pilot signals over a wireless communication channel using the set of transmission resources, wherein each of the pilot signals corresponds to a delta function in a delay-Doppler domain based on applying a symplectic transform to the pilot signals.

23. The apparatus of claim 22, wherein the set of transmission resources in the time-frequency domain occupied by any given pilot signal corresponds to a lattice comprising time instances uniformly distributed along a time axis and having a first step size and frequencies uniformly distributed along a frequency axis and having a second step size.

24. A wireless communication apparatus comprising a processor configured to implement a method comprising:

determining a maximum delay spread for a transmission channel;

determining a maximum Doppler frequency spread for the transmission channel;

determining, based on the maximum delay spread and the maximum Doppler frequency spread, a number of pilot signals in a time-frequency domain that can be transmitted using a set of two-dimensional transmission resources;

allocating the set of two-dimensional transmission resources to the number of pilot signals; and

transmitting the pilot signals over a wireless communication channel using the set of two-dimensional transmission resources, wherein each of the pilot signals corresponds to a delta function in a delay-Doppler domain based on applying a symplectic transform to the pilot signals.