Methods and devices for joint processing in massive MIMO systems

Patent metadata

Field	Value
Publication number	US-12438752-B2
Application number	US-202117553918-A
Country	US
Kind code	B2
Filing date	Dec 17, 2021
Priority date	Dec 17, 2021
Publication date	Oct 7, 2025
Grant date	Oct 7, 2025

Abstract

A distributed unit (DU) may include a transceiver configured to communicate with a plurality of radio units (RUs) that are configured to serve a plurality of user equipments (UEs). The DU may include a processor configured to determine RU precoding parameters for UEs served by a first RU set from the plurality of RUs based on estimated channel parameters for communication channels between the first RU set and at least one of interfering UEs served by other RUs from the plurality of RUs; to encode information indicating the determined precoding parameters for downlink transmissions to the first RU set and determine DU precoding parameters for downlink transmissions to the UEs served by the first RU set based on the determined RU precoding parameters; and/or precode communication signals based on the determined DU precoding parameters.

First claim

What is claimed is:

1. A distributed unit (DU) comprising:
a transceiver configured to communicate with a plurality of radio units (RUs) that are configured to serve a plurality of user equipments (UEs), and
a processor configured to:
determine RU precoding parameters for UEs served by a first RU set from the plurality of RUs based on estimated channel parameters representing communication channels between the first RU set and at least one of interfering UEs served by other RUs from the plurality of RUs, wherein the other RUs are distinct from RUs within the first RU set;
encode information indicating the determined RU precoding parameters for application to downlink transmissions to the first RU set;
determine DU precoding parameters for precoding, at the DU, communication signals intended for downlink transmissions via the first RU set to the UEs served by the first RU set based on the determined RU precoding parameters; and
precode the communication signals at the DU based on the determined DU precoding parameters prior to transmission towards the first RU set.

2. The distributed unit (DU) of claim 1 ,
wherein the processor is further configured to perform uplink channel estimation with at least one of Least-Squares (LS) based channel estimation or Minimum mean-square error (MMSE) based channel estimation or Bayesian inference-based channel estimation.

3. The distributed unit (DU) of claim 1 ,
wherein the processor is configured to determine the estimated channel parameters to apply a zero-forcing technique based on the fronthaul limitations.

4. The distributed unit (DU) of claim 3 ,
wherein the processor is further configured to determine the RU precoding parameters based on the zero-forcing technique applied to the estimated channel parameters for communication channels between the first RU set and the interfering UEs with respect to the first RU set.

5. The distributed unit (DU) of claim 3 ,
wherein the processor is further configured to determine the RU precoding parameters based on the estimated channel parameters for communication channels between the first RU set and a group of the UEs served by the first RU set;
wherein the group of the UEs are determined based on a channel gain parameter for each of the communication channels between the first RU set and the UEs served by the first RU.

6. The distributed unit (DU) of claim 3 ,
wherein the processor is further configured to determine a plurality of RU precoding parameters for the plurality of UEs;
wherein each RU precoding parameter for one of the plurality of UEs is determined based on estimated channel parameters between the first RU set and plurality of UEs not served by the first RU set.

7. The distributed unit (DU) of claim 3 ,
wherein the processor is further configured to aggregate estimated channel parameters that the zero-forcing technique is applied to into an aggregated channel matrix;
wherein the processor is further configured to calculate a null space of the aggregated channel matrix;
wherein the processor is further configured to decompose the null space of aggregated channel matrix based on a singular value decomposition (SVD) to obtain a diagonal matrix D comprising singular values, right singular vectors V, and left singular vectors U;
wherein the processor is further configured to determine the RU precoding parameters for a first UE of the UEs based on the right singular vectors, V.

8. The distributed unit (DU) of claim 7 ,
wherein the RU precoding parameters comprises a number of columns N of the right singular vectors from a matrix V, wherein the number of columns N is based on a number of data streams that the DU is configured to transmit data stream to the RU, in case the dimension of the null space of the aggregated channel matrix is greater than the number of data streams;
wherein the processor is further configured to rearrange the order of the singular values of the diagonal matrix D in an ascending order;
wherein the RU precoding parameters comprises N right singular vectors from the matrix V corresponding to the rearranged order of the singular values of the diagonal matrix.

9. The distributed unit (DU) of claim 8 ,
wherein the RU precoding parameters comprises a number N right singular vectors, wherein the number of vectors is based on the nullspace dimensions, in case the dimension of the null space of the aggregated channel matrix is less than the number of data streams.

10. The distributed unit (DU) of claim 9 ,
wherein the processor is further configured to determine the DU precoding parameters based on an effective channel matrix comprising parameters of a channel matrix of communication channels between the first RU set and UEs served by the first RU set and the RU precoding parameters;
wherein the processor is further configured to decompose the nullspace of the effective channel matrix based on a singular value decomposition (SVD) to obtain a diagonal matrix D comprising singular values, a first matrix of right singular vectors V with a dimension based on a number of antennas of the DU configured to transmit signals to the RU set, and a second matrix of left singular vectors U;
wherein the processor is further configured to determine the DU precoding parameters for the first UE based on the first matrix;
wherein the DU precoding parameters comprises a number of right singular vectors from the first matrix, wherein the number of vectors is based on a number of data streams that the DU is configured to transmit a data stream.

11. A radio unit (RU) comprising:
a transceiver configured to receive uplink radio communication signals from a plurality of user equipments (UEs) and transmit data streams to a distributed unit (DU) based on received uplink radio communication signals; and
a processor configured to:
determine precoding parameters based on estimated channel parameters for communication channels between the RU and interfering UEs served by other RUs coupled with the DU, wherein the estimated channel parameters are selected based on at least one of quality of service (QOS) parameters with respect to one or more groups of the plurality of UEs, positions of the UEs relative to the RU, or positions of the UEs relative to the respective group of the plurality of UEs, a parameter representing the fairness of the communication network, or availability of measurement results; and
precode the data streams to be transmitted to the DU based on the determined RU precoding parameters.

12. The radio unit (RU) of claim 11 ,
wherein the processor is further configured to obtain an aggregated channel matrix based on the selection of the estimated channel parameters.

13. The radio unit (RU) of claim 12 ,
wherein the processor is further configured to determine a number of groups to include in the estimated channel parameters based on the fronthaul limitation;
wherein the estimated channel parameters comprises the estimated channel parameters for the determined number of the interfering UEs;
wherein the processor is further configured to determine the RU precoding parameters based on a zero-forcing technique applied using the estimated channel parameters.

14. The radio unit (RU) of claim 13 ,
wherein the processor is further configured to operate in a first operation mode in which the processor applies the zero-forcing technique using signals received from one or more of the interfering UEs;
wherein the processor is further configured to operate in a second operation mode in which the processor performs maximum ratio combining to forward data streams to the DU based on signals received from the plurality

Assignees

• Intel Corp

Inventors

• Lu Lu
• Krishnamurthy Sundar
• Chen Kuilin Clark
• Hewavithana Thushara

Classifications

• H04L25/0258

  Channel estimation using zero-forcing criteria · CPC title

• H04L25/025

  using least-mean-square [LMS] method · CPC title

• H04L25/0252

  using third or higher order statistics · CPC title

• H04B17/391 Primary

  Modelling the propagation channel · CPC title

• H04L25/03343

  Arrangements at the transmitter end · CPC title