WO2023206264A1

WO2023206264A1 - Dl-prs transmission mechanism

Info

Publication number: WO2023206264A1
Application number: PCT/CN2022/089983
Authority: WO
Inventors: Pengli YANG; Chiao-Yao CHUANG; Jijian CHEN; Xuancheng Zhu; Xiao Liang
Original assignee: Mediatek Singapore Pte. Ltd.
Priority date: 2022-04-28
Filing date: 2022-04-28
Publication date: 2023-11-02

Abstract

This disclosure provides a new transmission mechanism of positioning reference signal (PRS) that can enhance the positioning performance of the RedCap UE. The UE with limited reception bandwidth receives the PRS resources of one or more positioning frequency layers by adjusting the center frequency according to the provided higher layer assistance information for downlink PRS configuration. Besides, the PRS resources of across positioning frequency layers are indicated with the associated spatial transmission filter and are partially overlapped in frequency domain. Thus, the UE is able to receive with a larger bandwidth by combining each of the limited reception bandwidth in different time instance, in this way, the measurement accuracy will be improved.

Description

DL-PRS TRANSMISSION MECHANISM

FIELD

This present disclosure relates generally to wireless communications, and more specifically, to techniques of positioning a user equipment (UE) with the limited measurement bandwidth.

BACKGROUND

A reduced capacity UE (RedCap UE) has the limited maximum bandwidth for downlink and uplink. In order to assist the RedCap UE to leverage the large bandwidth of positioning reference signal (PRS) for improving measurement accuracy and also to maintain the system RS overhead, a new transmission mechanism of PRS different from the transmission with large PRS bandwidth may be beneficial.

SUMMARY

The purpose of this disclosure is to propose a PRS transmission mechanism that can improve the positioning accuracy of RedCap UE.

In the first aspect of this disclosure, the UE receives the higher layer assistance information of one or more positioning frequency layers for downlink PRS configuration, including the spatial information and frequency position ofeach PRS resource.

In the second aspect ofthis disclosure, the PRS resources are transmitted from BS with three bandwidth types, respectively for larger-bandwidth PRS transmission, smaller-bandwidth PRS transmission, and larger-bandwidth PRS transmission in conjunction with smaller-bandwidth. The smaller-bandwidth PRS transmission with a different frequency layer maybe overlapped partially in frequency domain.

In the third aspect of this disclosure, the UE receives PRS resources of across positioning frequency layers indicated with the associated spatial transmission filter or indicated with the QCL relation between resources.

In the fourth aspect of this disclosure, the UE is able to receive PRS resources with a larger bandwidth as compared to the limited reception bandwidth after combining the received bandwidth in different time instance obtained by RF retuning.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is an example for a UE with limited reception bandwidth to perform reception bandwidth hopping in order to observe larger PRS bandwidth under the transmission of large PRS bandwidth with sufficient repetition number.

Fig. 2 is an example for a UE with limited reception bandwidth to perform reception bandwidth hopping in order to observe larger PRS bandwidth under the transmission of large PRS bandwidth with insufficient repetition number, the PRS with smaller bandwidth could be transmitted in conjunction with the larger-bandwidth PRS.

Fig. 3 is an example for a UE with limited reception bandwidth to perform reception bandwidth hopping in order to observe larger PRS bandwidth under the transmission of only small PRS bandwidth.

Fig. 4 (a) and Fig. 4 (b) are an example for the starting PRB index calculation for each positioning frequency layer when the starting PRB index increases with time instance.

Fig. 5 (a) and Fig. 5 (b) are an example for the starting PRB index calculation for each positioning frequency layer when the starting PRB index decreases with time instance.

Fig. 6 is an example of the PRS hopping together with existing transmission pattern that is sweeping after repetition.

Fig. 7 is an example of the PRS hopping together with existing transmission pattern that is repetition after sweeping.

DETAILED DESCRIPTION

Certain terms are used throughout the description and following claims to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to ... ". Also, the term "couple" is intended to mean either an indirect or direct electrical connection. Accordingly, ifone device is coupled to another device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections. The making and using of the embodiments of the disclosure are discussed in detail below. It should be appreciated, however, that the embodiments can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative, and do not limit the scope of the disclosure. Some variations of the embodiments are described. Throughout the various views and illustrative embodiments, like reference numbers are used to designate like elements.

Let us define that a positioning frequency layer consists of one or more PRS resource sets, and there is corresponding subcarrier spacing, cyclic prefix and the absolute frequency of a reference point which could also be named as point A.

Let us further define that a PRS resource set defines a same bandwidth for the associated PRS resources. Further, all the PRS resource sets within a same positioning frequency layer have the same bandwidth.

Let us further define that a PRS resource set defines a same starting PRB index with respect to the point A for the associated PRS resources. Further, all the PRS resource sets within a same positioning frequency layer have the same starting PRB index.

When a system with base stations is able to transmit the large-bandwidth PRS with sufficient repetition number, a UE with limited reception bandwidth may re-tune to change the center frequency with time. As such, the UE may be able to receive with a larger bandwidth as compared to the limited reception bandwidth after combining the received bandwidth in different time instance, as illustrated in Fig. 1. The large-bandwidth PRS is generally defined to be comparable to the channel bandwidth of a component carrier. The repetition of transmission generally indicates that the transmissions are based on a same spatial transmission filter. Further, for example, the time instance could be in the unit of slot time.

When a system with base stations is not able to transmit the larger-bandwidth PRS with sufficient repetition number, the smaller-bandwidth PRS with a different starting PRB index in frequency domain in a different time instance could be transmitted in conjunction with the larger-bandwidth PRS. As such, the UE may also be able to receive with a larger bandwidth as compared to the limited reception bandwidth after combining the received bandwidth in different time instance, as illustrated in Fig. 2. The smaller-bandwidth PRS is generally defined to be comparable to the maximum reception bandwidth of RedCap UEs, and the maximum reception bandwidth of RedCap UEs is generally smaller than the channel bandwidth of a component carrier.

When a system with base stations is not able to transmit any larger-bandwidth PRS, only the smaller-bandwidth PRS with a different starting PRB index in frequency domain in a different time instance could be transmitted. As such, the UE may also be able to receive with a larger bandwidth as compared to the limited reception bandwidth after combining the received bandwidth in different time instance, as illustrated in Fig. 3.

The smaller-bandwidth PRS transmission with a different starting PRB index in frequency domain in a different time instance maybe overlapped partially in frequency domain, as shown in Fig. 2 and Fig. 3. In this way, the UE is able to observe the same RS within a frequency domain segment in different time instance in order to estimate the change of the receiving phase due to RF re-tuning.

The starting PRB index associated to the small bandwidth transmission in next time instance based on that in current time instance is determined by

where

denotes the small transmission BW,

is the partial overlapping BW between two PRS transmissions in adjacent time instances,

is the positioning frequency layer transmission number, startPRB ₀ is the first starting frequency position of the PRS transmission for hopping, means the starting PRB index of the first small bandwidth PRS transmission, as illustrated in Fig. 4 and Fig. 5.

When the smaller-bandwidth PRS is transmitted in conjunction with larger-bandwidth PRS, the first starting PRB index of the small bandwidth transmission for hopping is determined by

or

N ^rep denotes the repetition factor for the larger-bandwidth PRS transmission,

denotes the large PRS transmission BW, startPRB _normal denotes the starting PRB index of the large PRS BW transmission, as illustrated in Fig. 4 (a) and Fig. 5 (a) . For example, in Fig. 4 (a) , the repetition factor of resource 0 under large BW transmission is 2, i.e., N ^rep = 2. The resource 0, resource 1 and resource 2 correspond to three positioning frequency layers with different starting PRB index startPRB _normal, startPRB ₀, startPRB ₁, respectively.

When there is no larger-bandwidth PRS is transmitted, startPRB ₀ is the lowest RB index of data transmission bandwidth, as illustrated in Fig. 4 (b) and Fig. 5 (b) . For example, in Fig. 4 (b) , the four resources, resource 0, resource 1, resource 2, and resource 3, corresponding to four positioning frequency layers with different starting PRB indexesstartPRB ₀, startPRB ₁, startPRB ₂, startPRB ₃, respectively.

When there is no smaller-bandwidth PRS is transmitted, as illustrated in Fig. 1, there is only one positioning frequency layer which contains resource 0 with the repetition factor 4 (N ^rep = 4) , and there is one starting PRB index.

The smaller-bandwidth PRS transmission with a different starting PRB index in frequency domain in a different time instance could be treated as the PRS transmission in a different positioning frequency layer, since the PRS resources and resource sets within a positioning frequency layer have the same starting PRB index and bandwidth. Further, the PRS resources of across positioning frequency layers may be indicated with the associated spatial transmission filter, or be indicated with the QCL relation between resources. For example, all the resources in Fig. 1-Fig. 5 are indicated with the associated spatial transmission filter.

Fig. 6 shows an example of the PRS hopping together with existing transmission pattern that is sweeping after repetition. The resource slot offset in each time instance and QCL relation between resources are also shown in Fig. 5.In this example, one resource set with large BW is for the normal UE. The system can additionally allocate two more resource sets with different startPRB to facilitate RedCap UE for obtaining larger PRS BW. For UE reception, these resources at

instance

0, 1, 2, 3 are QCL type D with each other, due to being associated with same spatial transmission filter. Similar QCL relation between resources in

instance

4, 5, 6, 7, or between resources in

instance

8, 9, 10, 11, or between resources in

instance

12, 13, 14, 15.

Fig. 7 shows an example of the PRS hopping together with existing transmission pattern that is repetition after sweeping. For UE reception, these resources at

instance

0, 4, 8, 12 are QCL type D with each other. Similar QCL relation between resources in

instance

1, 5, 9, 13, or between resources in

instance

2, 6, 10, 14, or between resources in

instance

3, 7, 11, 15.

While aspects of the present disclosure have been described in conjunction with the specific embodiments thereof that are proposed as examples, altematives, modifications, and variations to the examples may be made. Accordingly, embodiments as set forth herein are intended to be illustrative and not limiting. There are changes that may be made without departing from the scope of the claims set forth below.

Claims

A method of wireless communication of a user equipment (UE) , comprising:

receiving, from a serving base station of the UE, the higher layer assistance information of downlink positioning reference signal (PRS) configuration, wherein it comprises the PRS resource configuration of multiple frequency layers, each layer being associated with a starting PRB index;

measuring, at a baseband of the UE, the PRS within the reception bandwidth with first starting frequency position;

re-adjusting, at the RF frequency of the UE, for the measurement of the PRS within the reception bandwidth with multiple starting frequency positions; and

calculating the results based on the measured PRS within the reception bandwidth with multiple starting frequency positions.
The method of claim 1, wherein the PRS configuration further comprises the QCL relation between the PRS resources of across layers.
The method of claim 2, wherein the QCL relation is type D as Spatial Rx parameter.
The method of claim 1, further comprising:

requesting, by the UE, the DL-PRS transmission with several starting PRB indexes, each starting PRB index associated to the transmission in a time instance.
The method of claim 1, wherein the PRS resources associated to different positioning frequency layers has overlapping in frequency domain for transmission.
The method of claim 4, wherein the starting PRB index associated to the transmission in next time instance based on that in current time instance is determined by

or,

where
denotes the transmission BW,
is the overlapping BW between two PRS transmissions in adjacent time instances, n is the positioning frequency layer transmission number, startPRB ₀ is the first starting frequency position of the PRS transmission for hopping.