# Patent

## Title
Downlink user equipment selection


## Abstract

Aspects of the disclosure relate to a selection scheme implemented by a
scheduler in a multiple-input multiple-output (MIMO) network to identify which
users to schedule simultaneously during the same time slot. For downlink
communications and a particular frequency wholeband or sub-band, the scheduler
can determine downlink channel information using uplink channel information
for channels between base stations and UEs. The scheduler can then determine a
strength of the channels using the downlink channel information, order the UEs
using a fairness metric based on the channel strengths, and compute one or
more QR decompositions to identify whether a spatial dimension of a UE is
roughly or approximately orthogonal to spatial dimension(s) of other UEs
selected to be served during a time slot being scheduled. If the spatial
dimensions are roughly or approximately orthogonal, the scheduler selects the
UE to be served at the same time as other UEs already selected.



## Background
### CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.
16/900,674, entitled “DOWNLINK USER EQUIPMENT SELECTION” and filed on Jun. 12,
2020, which is a continuation of U.S. patent application Ser. No. 16/397,954,
entitled “DOWNLINK USER EQUIPMENT SELECTION” and filed on Apr. 29, 2019, the
entire disclosures of which are hereby incorporated by reference herein.

### BACKGROUND

### Technical Field

Embodiments of this disclosure relate to wireless communication systems, such
as cooperative multiple-input multiple output wireless communication systems.

### Description of Related Technology

The types of modern computing devices continues to increase along with the
differing and dynamic needs of each device. The wireless communication systems
providing services to such devices are facing increasing constraints on
resources and demands for quality and quantities of service. Accordingly,
improvements in providing wireless communication services, such as in a
multiple-input multiple-output system, are desired.

### SUMMARY

One aspect of the disclosure provides a network system comprising a plurality
of transmit antenna elements of one or more serving nodes. The network system
further comprises a scheduler in communication with the plurality of transmit
antenna elements, the scheduler comprising a processor and computer-executable
instructions, where the computer-executable instructions, when executed by the
processor, cause the scheduler to: determine downlink channel information for
channels between a plurality of receive antenna elements associated with a
plurality of user equipment (UEs) and the plurality of transmit antenna
elements; determine, for each receive antenna element in the plurality, a
