Last week Patently Apple posted a report titled "Apple Patent reveals their work on iPhone Communication designed for High-Speed Rail Networks in China & around the Globe."

With high-speed trains available throughout China, expanding around the globe and possibly the U.S. over time, Apple continues to work on a "Doppler Shift" solution. According to Apple, "effectively performing cellular communications may be complicated by Doppler shift in a high-mobility scenario such as cellular communications on a high-speed train (HST). In some deployments, the network may pre-compensate for the Doppler shift experienced by a rapidly moving Apple device (User Equipment or UE). However, the network may not be aware of the degree of Doppler shift to be pre-compensated. This is what Apple's patent aims to provide a solution for.

Doppler Shift Estimate Reporting With Pre-Compensation

Apple's invention covers apparatuses, systems, and methods for a reporting device to transmit a Doppler measurement report to a cellular base station. The reporting device may be a cellular transceiver installed on a high-speed vehicle, and the cellular base station may be a 5G NR gNB.

In some embodiments, the reporting device receives a configuration message from a first base station specifying one or more parameters of a Doppler measurement report.

In some embodiments, the reporting device performs one or more first Doppler measurements on the first base station and/or one or more second Doppler measurements on a second base station. The Doppler measurements measure a Doppler shift experienced by transmissions between the reporting device and the base stations.

In some embodiments, the reporting device transmits the Doppler measurement report to the first and/or second base stations, where the Doppler measurement report is based on the one or more first Doppler measurements and the one or more parameters. The Doppler measurement report may specify a differential between Doppler shifts of the first and second base stations. The Doppler measurement report may be used by the first and/or second base stations to perform Doppler pre-compensation on transmissions to the reporting device.

Note that the techniques described in the patent may be implemented in and/or used with a number of different types of devices, including but not limited to base stations, access points, cellular phones, portable media players, tablet computers, wearable devices, and various other computing devices.

This Summary is intended to provide a brief overview of some of the subject matter described in this document. Accordingly, it will be appreciated that the above-described features are merely examples and should not be construed to narrow the scope or spirit of the subject matter described herein in any way. Other features, aspects, and advantages of the subject matter are detailed in the patent.

Apple's patent FIG. 5 below is a schematic illustration of a high-speed train moving between two base stations, where the base stations perform pre-compensation to remove a Doppler shift; FIG. 6 is a flowchart diagram illustrating a method for a reporting device to provide a Doppler measurement report to one or more base stations responsive to receiving a configuration message; FIG. 7 is a flowchart diagram illustrating a method for a reporting device to autonomously provide a Doppler measurement report to one or more base stations.

Apple's patent FIG. 11B above represents one example of tables illustrating low and high latency requirements, respectively, for channel state information (CSI) reporting.

For wireless engineers wishing to review the finer details of Apple's invention, check out patent application 20230239010

Some of the Team Members on this Apple Project

• Haitong Sun:  Wireless System, Standardization Engineer
• Wei Zeng: Sr. Manager, Cellular System Engineering
• Chunxuan Ye: System Engineer
• Jie Cui: Emerging Technologist
• Huaning Niu: Wireless system engineer