WO2024000466A1

WO2024000466A1 - Schemes on gnss position fix in connected in iot ntn

Info

Publication number: WO2024000466A1
Application number: PCT/CN2022/102971
Authority: WO
Inventors: Wen Tang; Gilles Charbit; Yaohua CAI; Xu Huang; Xuan Wang; Ye Huang; Xuancheng Zhu
Original assignee: Mediatek Singapore Pte. Ltd.
Priority date: 2022-06-30
Filing date: 2022-06-30
Publication date: 2024-01-04
Also published as: CN117336679A

Abstract

This disclosure describes methods for UE re-acquire GNSS position fix in long connection time, to ensure the normal operation of NTN system. UE in RRC-connected state will need a new GNSS position fix in order to accommodate the accumulated time and frequency errors to reduce the possible radio link failure. High velocity UEs may need more frequent GNSS position fix during long connection time, which will increase UE power consumption. Besides, for long connection time, if UE always re-acquire GNSS position fix in idle, additional re-access to network is needed, which is costing in terms of signaling overhead and delay. The scheme designs re-acquire GNSS position fix in connected, so that save UE power consumption, to ensure the normal operation of IoT NTN system.

Description

SCHEMES ON GNSS POSITION FIX IN CONNECTED IN IOT NTN

FIELD

This disclosure relates generally to wireless communications, and, more particularly, to methods and apparatus about GNSS position fix in connected in IoT NTN.

BACKGROUND

In scenarios with large transmission delay, such as the IoT NTN, in order to ensure normal system operation, IoT NTN UE may need to re-acquire a valid GNSS position fix in long connection time, UE re-acquires GNSS position fix during RLF procedure is an effective solution.

SUMMARY

In NTN (Non-Terrestrial Network) system, due to large time delay and Doppler frequency shift, UE needs to do pre-compensation of time delay and frequency offset based on UE GNSS and ephemeris related parameters. To reduce the possible radio link failure, GNSS position fix should be supported during long connection. Based on this, considering the IoT NTN scenario, the invention designs schemes to do GNSS position fix, so that ensure normal system operation.

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE. The UE triggers GNSS position fix. The UE determines the scheme to do GNSS position fix based on GNSS status information. The UE obtains new GNSS position.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a diagram illustrating an example of the GNSS position fix indication information between UE and network.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as “elements” ) . These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

In scenarios with large transmission delay, such as NTN system, UE GNSS is necessary for time and frequency synchronization. At present, the method proposed in 3GPP R17 to do GNSS position fix is that UE needs to have a valid GNSS fix before going to connected and when the GNSS fix becomes outdated in RRC_CONNECTED mode, the UE goes to IDLE mode. The solution is not feasible for UE with potential long uplink transmission and additional re-access to network is needed, which is costing in terms of signaling overhead and delay. Depending on UE mobility, UE in RRC-connected state will need a new GNSS position fix in order to accommodate the accumulated time and frequency errors to reduce the possible radio link failure. Hence, in R18, there is conclusion that IoT NTN UE may need to re-acquire a valid GNSS position fix in long connection time. For GNSS position fix, hot start requires about 1～2 seconds, warm start requires several seconds, and cold start requires about 30 seconds.

This invention is motivated by, but not limited to, an IoT NTN scenario. In such a scenario, UE may need to re-acquire GNSS position fix in long connection time and needs to design the scheme to make UE re-acquire GNSS position fix in long connection time, to ensure the normal operation of NTN system.

NTN refers to a network that uses radio frequency and information processing resources carried on high, medium and low orbit satellites or other high-altitude communication platforms to provide communication services for UEs. According to the load capacity on the satellite, there are two typical scenarios: transparent payload and regenerative payload. The transparent payload mode means that the satellite will not process the signal and waveform in the communication service, but only forward the data as an RF amplifier. Regenerative payload mode refers to the satellite, besides RF amplification, also has the processing capabilities of modulation/demodulation, coding/decoding, switching, routing and so on.

In order to ensure the normal operation of IoT NTN system, UE needs to do pre-compensation of time delay and frequency offset based on UE GNSS and ephemeris related parameters. In 3GPP R17 for short sporadic transmission, the GNSS acquire has been discussed and relevant agreements have been obtained.

In 3GPP R18 for long-term connection, the GNSS related discussion has been made and relevant agreements have been obtained in RAN1 109e.

Depending on UE mobility, UE in RRC-connected state will need a new GNSS position fix in order to accommodate the accumulated time and frequency errors to reduce the possible radio link failure. UEs especially with high speed may need frequent GNSS position fix during long-term connections, which will introduce large power consumption. Besides, for long connection time, if UE always re-acquire GNSS position fix in idle, additional re-access to network is needed, which is costing in terms of signaling overhead and delay.

Hence, further scheme design needs to be carried out to re-acquire GNSS position fix in connected, so that save UE power consumption, to ensure the normal operation of IoT NTN system.

More specifically, we propose to consider the following alternatives for IoT NTN:

Alternative#1: GNSS position fix for UE in connected

GNSS position fix measurement length consists of at least the duration for UE to make GNSS measurement, may also include time duration to re-acquire DL synchronization and re-acquire NTN SIB if needed.

When GNSS position fix trigged in connected, UE assesses GNSS position fix measurement length; if GNSS position fix measurement length, X, is above new scheduling gap provided by a higher layer parameter ue-ScheduledGapGNSS, UE re-acquires GNSS in idle mode; if GNSS position fix measurement length, X, is not above new scheduling gap provided by a higher layer parameter ue-ScheduledGapGNSS, UE trigger procedure to re-acquire GNSS position fix in connected.

Note 1: X is reported when moving to RRC_CONNECTED. The network uses the value X to configure the UE with a new scheduling gap to at least make GNSS measurement, may also re-acquire DL synchronization and re-acquire NTN SIB if needed, where the gap is provided by a higher layer parameter ue-ScheduledGapGNSS. The value of the new scheduling gap shall be greater or equal to X so as to UE may re-acquire GNSS position fix in connected, where the value can be a cell_specific value indicated by SIB or a UE_specific value indicated by RRC signaling.

Note 2: At the end of the scheduling gap ue-ScheduledGapGNSS, the UE may trigger a scheduling request to report the new length of GNSS measurement and the new GNSS validity duration

Alternative#2: GNSS position fix for network in connected.

Based on the GNSS assistance information, which includes (remaining) GNSS validity duration and GNSS position fix measurement length, reported by UE and the timing error of UL reference signals, network configures a new scheduling gap, ue-ScheduledGapGNSS, during which the UE at least re-acquire GNSS position fix, and may also re-acquire DL synchronization and re-acquire NTN SIB if needed, in connected.

If the UE does not trigger a scheduling request at the end of the new scheduling gap, the netwprk assumes the UE has moved to RRC idle.

Note 3: During the new scheduling gap, ue-ScheduledGapGNSS, the network shall not schedule UE with DL assignment or UL grant.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more. ” The word “exemplary” is used herein to mean “serving as an example, instance, or illustration. ” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C, ” “one or more of A, B, or C, ” “at least one of A, B, and C, ” “one or more of A, B, and C, ” and “A, B, C, or any combination thereof” include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C, ” “one or more of A, B, or C, ” “at least one of A, B, and C, ” “one or more of A, B, and C, ” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. The words “module, ” “mechanism, ” “element, ” “device, ” and the like may not be a substitute for the word “means. ” As such, no claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for. ”

Claims

A method performed by a UE, comprising:

reporting GNSS assistance information;

receiving GNSS position fix indication information,

performing GNSS position fix acquisition procedure;

triggering a scheduling request to report new GNSS position validity duration,
The method of Claim 1, where report the GNSS assistance information in RRC_CONNECTED, which comprising:

(remaining) GNSS validity duration,

GNSS position fix measurement length.
The method of Claim 2, wherein the GNSS position fix measurement length comprising:

the duration for UE to make GNSS measurement,

or the duration for UE to make GNSS measurement and the duration for UE to re-acquire DL synchronization,

or the duration for UE to make GNSS measurement and the duration for UE to re-acquire DL synchronization and re-acquire NTN SIB.
The method of Claim 1, wherein the GNSS position fix indication information comprising:

the new scheduling gap indicated by a higher layer parameter ue-ScheduledGapGNSS,

the timer T31Y indicated by a higher layer parameter GNSSMeasurementTimer.
The method of Claim 4, the new scheduling gap, ue-ScheduledGapGNSS, is a cell_specific value indicated and updates by SIB,

or a UE_specific value indicated and updates by RRC signaling,

the value of the new scheduling gap shall be greater or equal to GNSS position fix measurement length with the unit 1 second;

and the timer T31Y, GNSSMeasurementTimer, is a cell_specific value indicated and updates by SIB,

or a UE_specific value indicated and updates by RRC signaling,

can be set to the duration of new gap, ue-ScheduledGapGNSS.
The method of Claim 1, if the GNSS position fix measurement length is above new scheduling gap:

perform the actions upon leaving RRC_CONNECTED,

perform GNSS position fix acquisition procedure in idle.
The method of Claim 1, if the GNSS position fix measurement length is not above new scheduling gap:

perform GNSS position fix procedure acquisition in connected,

start timer T31Y,

acquire GNSS position fix in timer T31Y,

upon successful acquisition of GNSS position fix,

acquire DL synchronization and acquire NTN SIB if needed before timer T31Y expiry;

upon successful acquisition of DL synchronization and acquire NTN SIB if needed,

reset timer T31Y,

trigger a scheduling request to report new GNSS validity duration information via MAC CE or RRC signaling, at

the end of the scheduling gap ue-ScheduledGapGNSS.

or upon not successful acquire GNSS position fix before timer T31Y expiry,

perform the actions upon leaving RRC_CONNECTED,

reset timer T31Y.
A method performed by a network, comprising:

receiving GNSS assistance information,

transmitting GNSS position fix indication information,

receiving a scheduling request.
The method of Claim 8, wherein the GNSS assistance information comprising:

(remaining) GNSS validity duration,

GNSS position fix measurement length.
The method of Claim 9, wherein the GNSS position fix measurement length comprising:

the duration for UE to make GNSS measurement,

or the duration for UE to make GNSS measurement and the duration for UE to re-acquire DL synchronization,

or the duration for UE to make GNSS measurement and the duration for UE to re-acquire DL synchronization and

re-acquire NTN SIB.
The method of Claim 8, wherein the GNSS position fix indication information comprising:

the new scheduling gap indicated by a higher layer parameter ue-ScheduledGapGNSS,

the timer T31Y indicated by a higher layer parameter GNSSMeasurementTimer.

where new scheduling gap and the timer is set based on GNSS position fix measurement length.
The method of Claim 8, if the network does not receive a scheduling request at the end of the new scheduling gap, the network assumes the UE has moved to RRC idle.
The method of Claim 8, if network receives a scheduling request at the end of the new scheduling gap from the UE, then transmits UL grant for UE to transmit new GNSS assistance information.