WO2024197847A1

WO2024197847A1 - Methods for papr reduction

Info

Publication number: WO2024197847A1
Application number: PCT/CN2023/085577
Authority: WO
Inventors: Junqiang CHENG; Tao Chen; Chenmeng LI
Original assignee: MediaTek Singapore Pte Ltd
Current assignee: MediaTek Singapore Pte Ltd
Priority date: 2023-03-31
Filing date: 2023-03-31
Publication date: 2024-10-03
Anticipated expiration: 2025-09-30

Abstract

This disclosure describes methods for PAPR reduction when sequence/signal/bits block is repeated in frequency domain. Specifically, a method of scrambling among repetitions and a method of cyclic shift regarding location and phase of the element within sequence/signal/bits block aiming different repetitions are disclosed.

Description

METHODS FOR PAPR REDUCTION

FIELD

The invention discussed below relates generally to wireless communication systems, and more particularly, to methods for PAPR reduction.

BACKGROUND

Peak-to-average-ratio (PAPR) is a critical parameter in wireless communication system. The signal with high PAPR may cause excessive intermodulation distortion of the power amplifier. Additionally, some mechanism in wireless communication system may result in high PAPR issue. For example, signal repetition in frequency domain may increase the PAPR due to superposition in time domain, and a longer signal in frequency domain may also increase the PAPR. Therefore, the methods for PAPR reduction especially when signal is repeated in frequency domain are needed to solve the issues caused by high PAPR.

SUMMARY

The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

Various aspects of the present disclosure relate to the methods of PAPR reduction in the wireless communication system. For a bit block/sequence/signal repeated in frequency domain, the superposition in time domain may lead to a higher PAPR. In this case, some methods are disclosed to reduce the PAPR for a sequence repeated in frequency domain.

In one aspect of this disclosure, scrambling method can be applied among repetition (s) /repeated sequence (s) . Example, a longer scrambling sequence can be generated, which can be applied to during and/or after the sequence repetition (s) . The length of longer scrambling sequence can be based on the total length of the transmitted sequence to be scrambled after repetition in frequency domain with or without consideration of gap between repetitions, and/or based on the total occupied channel bandwidth, and/or a (pre-) configured channel bandwidth (e.g., 20MHz) . The scrambling sequence generator can be initialized with a (pre-) configured initialization factor (e.g., a PN sequence with a initialization factor of cell ID or a specific number) . The scrambling procedure shall be performed before the procedure of modulation and/or mapping to physical resources.

In another aspect of this disclosure, cyclic shift method can be applied among repetition (s) /repeated sequence (s) . The cyclic shift can be applied in different manners. For example, it can be applied to cyclically shift the element location within a sequence aiming different repetition (s) . Alternatively, it can be applied to cyclically shift the element phase within a sequence aiming different repetition (s) . Alternatively, the combination of the above two manners can also be applied among different repetition (s) .

In another aspect of this disclosure, a cyclic shift factor can be (pre-) configured and/or indicated to reflect the procedure of cyclic shift. For example, the cyclic shift factor can be (pre-) configured as a cyclic shift phase set to be applied on each element within a sequence aiming different repetition (s) . The length of the cyclic shift phase set can be (pre-) configured and/or indicated based on the total length of the transmitted sequence to be scrambled after repetition in frequency domain with or without consideration of gap between repetitions, and/or based on the total occupied channel bandwidth, and/or a (pre-) configured channel bandwidth (e.g., 20MHz) . The cyclic shift phase set can be initialized as a (pre-) configured sequence (e.g., a ZC sequence or a sequence with idea auto-correlation) . The procedure of cyclic shift should be performed before the procedure of physical resource mapping.

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 figures 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

FIG. 1 illustrates an exemplary diagram of the disclosed scrambling method, where the n^th transmission of the bit block after repetition is scrambled by the n^th sub-set of scrambling sequence.

FIG. 2 illustrates an exemplary diagram of the disclosed scrambling method, where the total bit blocks after repetition are scrambled as one component by the total scrambling sequence.

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.

This invention is motived by, but not limited to, a scenario where the bit block/sequence/signal is repeated in frequency domain in wireless communication system. In such scenario, the sequence repetition in frequency domain may lead to signal superposition in time domain thus may result in a high PAPR. To solve this problem, some methods are proposed in this disclosure including scrambling method and cyclic shift method to reduce the PAPR after sequence repetition in frequency domain.

In one aspect of the disclosure, the scrambling method is applied among sequence repetition in frequency domain. Specifically, a longer scrambling sequence can be generated to match the length of repeated sequence based on some rules. The rules can be (pre-) configured and/or indicated. Specifically, the rules can be set to include, for example, the scrambling sequence length equals to the total length of the repeated sequence without consideration of the gap between repetitions, or the scrambling sequence length equals to the total length of the repeated sequence with consideration of the gap between repetitions, or the scrambling sequence length can be set as a length of occupied channel bandwidth, and/or specific channel bandwidth (e.g., 20MHz) and numerology. The length mentioned here can be regarded as the number of resource element (RE) in frequency domain. The sequence can be scrambled during and/or after repetition (s) .

For example, assume the original sequence is a block of bits b (0) , …, b (M-1) , where M is the number of bits transmitted on the channel (e.g., physical sidelink broadcast channel) . This sequence is transmitted N times by repetition in frequency domain, and there is a gap L between the repetition (s) . The value of N and L can be (pre-) configured and/or (pre-) defined based on some requirement (e.g., OCB and/or coverage requirement) . Assume a long scrambling sequence is c (i) , which can be a pseudo-random sequence and the specific generation equation and initialization factor can be (pre-) configured. Additionally, based on the description before, the length of this long scrambling sequence c (i) can be N×M if the gap L between the repetition (s) is not considered, or N×M+ (N-1) ×L if the gap L between the repetition (s) is considered, or a specific value determined by a specific channel bandwidth and numerology.

In this disclosure, an equation is given as an example to illustrate the method of scrambling among repetitions. Assume the original bits block is b (0) , …, b (M-1) , where M is the number of bits transmitted in physical channel. The original bits block is transmitted N times by repetition in frequency domain and there is a gap L between the repetition (s) :

Where the footnote n, 1≤n≤N represents the transmission index (i.e., the n^th transmission of the original bits block) . For example, b_n represents the n^th transmission of the original bits block in the manner of repetition. Therefore, it can be concluded that b₁ (i) =b₂ (i) =…=b_N (i) , 0≤i≤M-1. This assumption is validated through the disclosure.

The transmission bits block after repetition shall be scrambled prior to the procedure of modulation and/or physical resource mapping. After scrambling procedure, a block of scrambled bits can be obtained according to

Where n, 1≤n≤N represents the transmission index mentioned before, and i, 0≤i≤M-1 is the bit index within the bits block. More specifically, an example can be

Where c_n (i) is the scrambling sequence of the n^th transmission, which is a sub-set of the long scrambling sequence c (i) . Specifically, for the case that the length of the long scrambling sequence c (i) is (pre-) configured and/or (pre-) defined as N×M, it can be divided into N sub-set, each with a length of M. In this case, the n^th sub-set of the long scrambling sequence is applied to scramble the n^th transmission of the bits block after repetition (s) .

As in Figure 1, one example is given to reflet the above scrambling method. In this example, the bits block is transmitted N times by repetition in frequency domain and a gap of length L is (pre-) configured between repetitions. Therefore, the total length of the transmitted bits block is N×M+ (N-1) ×L. Besides, in this example, the long scrambling sequence is generated with a total length of N×M and can be further divided into n sub-set each with a length of M. Therefore, the n^th transmission of the bits block after repetition (s) can be scrambled by the n^th sub-set of the long scrambling sequence as shown in the figure. Additionally, as mentioned, the length of scrambling sequence can be (pre-) configured and/or indicated as N×M+ (N-1) ×L, or a length of a specific bandwidth. In these cases, the principle shown in Figure 1 can also be applied.

Additionally, in this disclosure, the transmitted bits block after repetition can be regarded as one component when applying scrambling sequence. In this case, it is required that the length of scrambling sequence should be no less than the length of the transmitted bits block after repetition with consideration of gap between repetitions. For example, as shown in Figure 2, for the case that the length of scrambling sequence is set as N×M+ (N-1) ×L, it can be applied after the bits block repetition. That means the transmitted bits block after repetition with a length of N×M+ (N-1) ×L can be treated as one component to be scrambled with a scrambling sequence with a length of N×M+ (N-1) ×L.

It should be also noted that, in this disclosure, the equation to generate scrambling sequence can be (pre-) configured and/or indicated as same or different among different repetitions. In other words, the function f (b_n (i) ) can be a piecewise function for each piece of length M.

In another aspect of the disclosure, cyclic shift method can be applied among repetitions in frequency domain. The cyclic shift defined in this disclosure can be applied in different manners. One manner is cyclic shifted location of the element within a sequence among repetition. Specifically, the value of the element within the sequence may not be changed in this manner, but the location of each element can be cyclic shifted among repetitions. For example, assume the original sequence is b (0) , b (1) , …, b (M-2) , b (M-1) . The n^th transmission of this sequence can be b (K) , b (K+1) , …, b (M-1) , b (0) , …, b (K-1) . The value of K can be (pre-) configured and/or indicated.

Additionally, the cyclic shift can be applied in a second manner, i.e., cyclic shifted phase of the element within a sequence among repetitions. Specifically, in this manner, the location of each bit within the bits block may not be changed, but a cyclic shifted phase/phase rotation can be added to each element within a sequence. A long cyclic shifted phase set θ can be (pre-) configured. The length of the long cyclic shifted phase set can be (pre-) configured to match the total length of the sequence after repetition based on some rules. For example, the rules can include, cyclic shifted phase set length equals to the total length of the repeated bits block without consideration of the gap between repetitions, and/or cyclic shifted phase set length equals to the total length of the repeated bits block with consideration of the gap between repetition, and/or cyclic shifted phase set length can be set as a length of occupied channel bandwidth and/or a specific channel bandwidth (e.g., 20MHz) . The length mentioned here can be regarded as the number of resource element (RE) in frequency domain.

Assume the original sequence is b (0) , …, b (M-1) , where M is the number of elements transmitted in physical channel. The transmission bits block shall be cyclic shift prior to physical resource mapping. The cyclic shift procedure can be performed after and/or during the sequence repetition. After cyclic shift procedure, the n^th transmission of the bits blockcan be obtained according to

Where i, 0≤i≤M is the element index within a sequence, and n, 1≤n≤N represents transmission index. is the i^th cyclic shift phase of the n^th sub-set of the long cyclic shift phase set θ. For example, for the case that the length of long cyclic shift phase set equals to the total length of the transmitted bits block (assuming transmission time is N) without consideration of the gap between repetitions, the length of long cyclic shift phase set is N×M. Then it can be divided into N sub-set, each with a length of M. In this case, the n^th sub-set of cyclic shift phase set corresponding to the n^th transmission of the bit block.

Additionally, the transmitted bits block after repetition can be regarded as one component when applying cyclic shift phase set. In this case, it is required that the length of the cyclic shift phase set should be no less than the length of the transmitted bits block after repetition with consideration of gap I between repetitions. For example, for the case that the length of the cyclic shift phase set is set as N×M+(N-1) ×L, it can be applied after the sequence repetition is done. That means the transmitted sequence after repetition with a length of N×M+ (N-1) ×L can be treated as one component to be phase shifted with a cyclic shift phase set with a length of N×M+ (N-1) ×L.

In this disclosure, it should be noted that the combination of cyclic shift location and cyclic shift phase can be applied among repetitions with the principle described above.

In another aspect of the disclosure, the receiver can be (pre-) configured and/or indicated to receive a long sequence (i.e., the repeated sequence after repetition) , and/or a single sequence (i.e., the single sequence before repetition) based on the legacy receiver.

In another aspect of the disclosure, for the transmission on unlicensed spectrum, a new field can be added to the 1^st stage SCI to indicate the utilization of intra-cell guard band. For example, a new field of one bit (e.g., the reserved bit of legacy 1^st SCI) can be added to the 1^st stage SCI to indicate whether the PRBs within intra-cell guard band is used or not. Alternatively, a new filed of multi-bits can be added to the 1^st SCI to indicate more information on the utilization of the intra-cell guard band (e.g., whether and how the PRBs within the intra-cell guard band is used) . The indicated intra-cell guard band can be the intra- cell guard band immediately following/next to the RB set containing the corresponding 1^st stage SCI.

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, ” “UE, ” 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. ”

While aspects of the present disclosure have been described in conjunction with the specific embodiments thereof that are proposed as examples, alternatives, 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 PAPR reduction when a bit block is transmitted multiple times by repetition in frequency domain, wherein a scrambling method among repetitions can be applied.
The method of claim 1, wherein the equation of the scrambling sequence generation among different repetitions can be (pre-) configured and/or indicated as same and/or different.
The method of claim 1, wherein the length of the scrambling sequence can be (pre-) configured and/or indicated.
The method of claim 3, wherein the length of scrambling sequence can be defined as the total length of the repeated bit blocks with or without consideration of the gap between repetitions, and/or can be defined as a length of the occupied channel bandwidth and/or a specific channel bandwidth.
The method of claim 1, wherein the scrambling sequence can be applied regarding each repeated bit block, and/or regarding the total bit blocks after repetition with consideration of gap between repetitions.
The method of claim 1, wherein the scrambling sequence can be (pre-) configured and/or indicated as a specific sequence (e.g., pseudo-random sequence sequence) .
The method of claim 1, wherein the initialization parameter used to generate scrambling sequence can be initialized at the start of each S-SSB.
The method of claim 1, wherein the scrambling can be applied during and/or after bit block repetition.
The method of claim 1, wherein the scrambling can be applied among repetitions before modulation procedure.
The method of claim 1, wherein a cyclic shift method among sequence repetitions can be applied.
The method of claim 10, wherein the cyclic shift can be applied to adjust the location/index of the element within the sequence aiming different repetitions.
The method of claim 7, wherein the cyclic shift can be applied to adjust the phase of the element within the sequence aiming different repetitions.
The method of claim 12, wherein the cyclic shift can be defined as a cyclic shift phase set.
The method of claim 13, wherein the equation to generate cyclic shift phase set can be (pre-) configured and/or indicated (e.g., a ZC sequence and/or a sequence with an idea auto-correlation) .
The method of claim 13, wherein the length of cyclic shift phase set can be (pre-) configured and/or indicated.
The method of claim 15, wherein the length of cyclic shift phase set can be defined as the total length of the repeated sequence with or without consideration of the gap between repetitions, and/or can be defined as a length of the occupied channel bandwidth and/or a specific channel bandwidth.
The method of claim 10, wherein the cyclic shift phase set can be applied regarding each repeated sequence, and/or regarding the total sequences after repetition with consideration of gap between repetitions.
The method of claim 10, wherein the cyclic shift can be applied during and/or after the sequence repetition.
The method of claim 10, wherein the cyclic shift can be applied before the procedure of physical resource mapping.