WO2017031675A1

WO2017031675A1 - Transmission repetition reduction in a wireless communication system

Info

Publication number: WO2017031675A1
Application number: PCT/CN2015/087973
Authority: WO
Inventors: Xinquan LIU; Zukang Shen
Original assignee: Lenovo Innovations Limited (Hong Kong)
Priority date: 2015-08-25
Filing date: 2015-08-25
Publication date: 2017-03-02

Abstract

Apparatuses, methods, and systems are disclosed for transmission repetition reduction. One apparatus includes a transmitter that transmits a Physical Downlink Shared Channel ("PDSCH" ) transport block ( "TB" ) in a first set of subframes to a device. In such an embodiment, a second set of subframes may be a proper subset of the first set of subframes. In various embodiments, the apparatus includes a receiver that receives a positive acknowledgement from the device using a first hybrid automatic repeat request acknowledgement ( "HARQ-ACK" ) resource. In such embodiments, the positive acknowledgement may indicate that the PDSCH TB is correctly decoded from the second set of subframes. In certain embodiments, the apparatus includes a processor that determines a correspondence between the first HARQ-ACK resource and the second set of subframes.

Description

TRANSMISSION REPETITION REDUCTION IN A WIRELESS COMMUNICATION SYSTEM

FIELD

The subject matter disclosed herein relates generally to wireless communications and more particularly relates to transmission repetition reduction in a wireless communication system.

BACKGROUND

The following abbreviations are herewith defined, at least some of which are referred to within the following description.

3GPP Third Generation Partnership Project

ACK Positive-Acknowledgment

BPSK Binary Phase Shift Keying

CAZAC Constant Amplitude Zero Auto Correction

CCE Control Channel Element

CP Cyclic Prefix

CSI Channel State Information

CSS Common Search Space

DCI Downlink Control Information

DL Downlink

eMTC Enhanced Machine-Type Communications

eNB Evolved Node B

EPDCCH Enhanced Physical Downlink Control Channel

ETSI European Telecommunications Standards Institute

FBE Frame Based Equipment

FDD Frequency Division Duplex

FDMA Frequency Division Multiple Access

FEC Forward Error Correction

HARQ Hybrid Automatic Repeat Request

LBE Load Based Equipment

LTE Long Term Evolution

M-PDCCH MTCPhysical Downlink Control Channel

MCL Minimum Coupling Loss

MCS Modulation and Coding Scheme

MTC Machine-Type Communications

MU-MIMO Multi-User, Multiple-Input, Multiple-Output

NACK or NAK Negative-Acknowledgment

OFDM Orthogonal Frequency Division Multiplexing

PCell Primary Cell

PBCH Physical Broadcast Channel

PDCCH Physical Downlink Control Channel

PDSCH Physical Downlink Shared Channel

PHICH Physical Hybrid ARQ Indicator Channel

PRACH Physical Random Access Channel

PRB Physical Resource Block

PUCCH Physical Uplink Control Channel

PUSCH Physical Uplink Shared Channel

QoS Quality of Service

QPSK Quadrature Phase Shift Keying

RAR Random Access Response

RRC Radio Resource Control

RX Receive

SC-FDMA Single Carrier Frequency Division Multiple Access

SCell Secondary Cell

SCH Shared Channel

SIB System Information Block

SR Scheduling Request

TBS Transport Block Size

TDD Time-Division Duplex

TDM Time Division Multiplex

TX Transmit

UCI Uplink Control Information

UE User Entity/Equipment (Mobile Terminal)

UL Uplink

UMTS Universal Mobile Telecommunications System

WiMAX Worldwide Interoperability for Microwave Access

In wireless communications networks, MTC may be an opportunity for revenue generation for mobile operators. One objective of eMTC is to specify a new UE category which facilitates reduced cost and power consumption as compared to MTC. Another objective for eMTC is to obtain 15～20dB coverage enhancement when compared to legacy LTE systems. The bandwidth of eMTC UE is reduced to 1.4 megahertz ( “MHz” ) while the whole system bandwidth may be up to 20 MHz. In certain configurations, a single eMTC UE can tune to different 1.4MHz narrow bandsacross the whole system bandwidth over time.

For coverage enhancement, the target MCL is 155.7 decibel ( “dB” ) for both FDD and TDD. Table 1 shows the MCL for different channels of LTE category 1 UE. AsTable 1 illustrates, to achieve the 155.7dB target, different channels have different gaps.

Table 1: MCL Summary for LTE Category 1 UE (see TR 36.888 Table 9.2.1-1)

Repetition is used to enhance the coverage for eMTC UEs. As may be appreciated, repetition may occupy more resources, thereforeusing a proper number of repetitions fora channel condition of an eMTC UE is optimal. As can be seen from Table 1, different channels may be transmittedwith different numbers of repetitions. In certain configurations, there may be four repetition levels defined. The lowest repetition level corresponds to normal coverage. Other repetition levels may be, in certain embodiments, 5dB higher than the previous level.

An eMTC UE may be identified by the PRACH transmitted by the UE. For example, in a SIB an eNB may provide a set of PRACH resources (e.g. time, frequency, and preamble) each associated with a repetition level. The set of PRACH resources for eMTC UEs may be different from the set of PRACH resources for regular UEs. So according to different time/frequency resources or preamble sequence an eNB may determine whether a UE is aneMTC UE or not. If it is an eMTC UE the eNB may also know roughly the required repetition level of it, based on the PRACH repetition level. Then the eNB may determine the RAR repetition level according to the PRACH repetition level. After the initial random access procedure, for transmission of a physical data channel with repetition, the repetition numbermay be dynamically determined and indicated bythe network in the DL or UL grant.

As may be appreciated, the eMTC UEs cannot receive PDCCH (because PDCCH spans across the whole system bandwidth as defined by 3GPP) in a system with a bandwidth larger than 1.4MHz. Using M-PDCCH (which is based on EPDCCH as defined by 3GPP) instead may be a natural solution for transmitting a control message to an eMTC UE. M-PDCCH may only be transmitted on a subset of the PRBs within the system bandwidth. The number of M-PDCCH repetitions may be determined during the M-PDCCH initialization and may be changed by higher layers, e.g. via RRC signaling. The number of repetitions for unicast PDSCH may be dynamically indicated by the DCI.

In some configurations, a HARQ mechanism is used for the data retransmission. When a UE receives PDSCH data, the UE needs to report whether the PDSCH is decoded correctly. Therefore, ACK/NACK information may be sent to the eNB to indicate whether the UE has successfully decoded the data or not. The eNB may determine whether retransmission is needed based on the ACK/NACK information. Throughout this disclosure, ACK/NACK or HARQ-ACK refers to ACK or NACK collectively. The term ACK/NACK and HARQ-ACK are used inter-changeably.

The ACK/NACK information may be transmitted on PUCCH using PUCCH Format 1a/1b as defined by 3GPP. The PUCCH Format 1a/1b related information is shown in Table 2. For an eMTC UE, only one transport block carrying unicastdatamay be transmitted on PDSCH in a subframe. Therefore, only one ACK/NACK bit needs to be fed back in an UL subframe.

Table 2: PUCCH Format 1a/1b

For PUCCH Format 1a/1b, a length-12 CAZAC sequence is transmitted in a PRB in the frequency domain. Due to the CAZAC property of the sequence, different cyclic shifts of the sequence are orthogonal to each other, even if they are transmitted in the same PRB. Therefore, different cyclic shifts of the sequence may carry different information bits. The maximum number of available cyclic shifts is 12 for PUCCH Format 1a/1b. Furthermore, an orthogonal cover code may be applied in a time domain for PUCCH Format 1a/1b, and 3 orthogonal cover codes are provided in a normal CP case. Therefore, a maximum of 12 x 3 ＝ 36 orthogonal PUCCH Format 1a/1b resources are available within a PRB. Since a PUCCH Format 1a/1b resource maybe used to carry the ACK/NACK information, a PUCCH Format 1a/1b resource may sometimes be referred to as an ACK/NACK resource or HARQ-ACK resource in this disclosure. It is noted that if some other PUCCH Format is used to carry the ACK/NACK information, an ACK/NACK or HARQ-ACK resource in this disclosure mayalso refer to a resource of the other PUCCH Format. A PUCCH Format 1a/1b resource maybe identified by a corresponding PUCCH Format 1a/1b resource index. The PUCCH Format 1a/1b resource index determines the PRB, the cyclic shift, and orthogonal cover codes of the PUCCH Format 1a/1b resource.

As may be appreciated, it is supported in LTE that CSI is fed back by a UE, in order to assist link adaptation. In various configurations, CSI may be reported periodically or aperiodically. Periodic CSI reporting may be configured by an eNB via higher layer signaling, such as RRC. Aperiodic CSI reporting may be triggered via aperiodic CSI triggering bits included in a UL grant, which schedules PUSCH on which the aperiodic CSI may be transmitted. For an eMTC UE in coverage enhancement, periodic CSI reporting may not be supported, because reporting the periodic CSI may consume significant amount of UE power. Furthermore, transmission of aperiodic CSI by an eMTC may also increase the eMTC UE’s power consumption. Therefore, with less accurate CSI of an eMTC UE at the eNB, the network may use a repetition number much larger than the UE actually needs for correctly receiving the PDSCH. There may be at least two problems that exist when the repetition number is much larger than the UE actually needs. One is that an eNB may allocate more time/frequency resources to perform the PDSCH repetition, while the UE may use fewer repetitions to decode data successfully. This leads to inefficient usage of resources. Another problem is if the eMTC UE always uses the indicated repetition number to receive the PDSCH while the UE can use fewer repetitions to decode data successfully, the UE power consumption may be higher than necessary.

Throughout this disclosure, arepetition of a PDSCH refers to the operation of repeatedly transmitting a same PDSCH transport block in a plurality of subframes. The PDSCH TB includesinformation bits before a FEC encoder. Different encoded bits (or redundancy versions) after the FEC encoder corresponding to the same PDSCH TB may be transmitted in different subframes within the plurality of subframes. Therefore, “repetition in a number of subframe” in this disclosure does not necessarily mean that an exact same signal is transmitted over the radio channel in the number of subframes, rather it means that the same PDSCH TB is transmitted in the number of subframes.

Throughout this disclosure, an eMTC UE in coverage enhancement at least refers to an eMTC UE which requires more than one subframe to receive a PDSCH TB correctly.

BRIEF SUMMARY

Apparatuses for transmission repetition reduction are disclosed. Methods and systems also perform the functions of the apparatus. In one embodiment, the apparatus includes a transmitter that transmits a Physical Downlink Shared Channel ( “PDSCH” ) transport block (“TB” ) in a first set of subframes to a device. In such an embodiment, a second set of subframes may be a proper subset of the first set of subframes. In various embodiments, the apparatus includes a receiver that receives a positive acknowledgement from the device using a first hybrid automatic repeat request acknowledgement ( “HARQ-ACK” ) resource. In such embodiments, the positive acknowledgement may indicate that the PDSCH TB is correctly decoded from the second set of subframes. In certain embodiments, the apparatus includes a processor that determines a correspondence between the first HARQ-ACK resource and the second set of subframes.

In a further embodiment, the processor that determines the correspondence between the first HARQ-ACK resource and the second set of subframes further determines the correspondence between the first HARQ-ACK resource and the second set of subframes based on a predetermined mapping between the first HARQ-ACK resource and the second set of subframes. In some embodiments, the predetermined mapping between the first HARQ-ACK resource and the second set of subframes is fixed or configured by higher layer signaling. In certain embodiments, the predetermined mapping establishes a correspondencebetween a second HARQ-ACK resource and the first set of subframes and the second HARQ-ACK resource is different from the first HARQ-ACK resource.

In another embodiment, the processor that determines the correspondence between the first HARQ-ACK resource and the second set of subframes further determines the correspondence between the first HARQ-ACK resource and the second set of subframes based on a predetermined mapping between the first HARQ-ACK resource and a cardinality of the second set of subframes. In various embodiments, the predetermined mapping between the first HARQ-ACK resource and the cardinality of the second set of subframes is fixed or configured by higher layer signaling. In one embodiment, the predetermined mapping establishes a correspondencebetween a second HARQ-ACK resource and a cardinality of the first set of subframes and the second HARQ-ACK resource is different from the first HARQ-ACK resource.

A method for transmission repetition reduction, in one embodiment, includes transmitting a Physical Downlink Shared Channel ( “PDSCH” ) transport block ( “TB” ) in a first set of subframes to a device. In such an embodiment, a second set of subframes may be a proper subset of the first set of subframes. In some embodiments, the method includes receiving a positive acknowledgement from the device using a firsthybrid automatic repeat request acknowledgement ( “HARQ-ACK” ) resource. In such embodiments, the positive acknowledgement may indicate that the PDSCH TB is correctly decoded from the second set of subframes. In a further embodiment, the method includes determining a correspondence between the first HARQ-ACK resource and the second set of subframes.

In some embodiments, determining the correspondence between the first HARQ-ACK resource and the second set of subframes includes determining the correspondence between the first HARQ-ACK resource and the second set of subframes based on a predetermined mapping between the first HARQ-ACK resource and the second set of subframes. In one embodiment, the predetermined mapping between the HARQ-ACK resource and the second set of subframes is fixed or configured by higher layer signaling. In certain embodiments, the predetermined mapping establishes a correspondencebetween a second HARQ-ACK resource and the first set of subframes and the second HARQ-ACK resource is different from the first HARQ-ACK resource.

In some embodiments, determining the correspondence between the first HARQ-ACK resource and the second set of subframes includes determining the correspondence between the first HARQ-ACK resource and the second set of subframes based on a predetermined mapping between the first HARQ-ACK resource and a cardinality of the second set of subframes. In various embodiments, the predetermined mapping between the first HARQ-ACK resource and the cardinality of the second set of subframes is fixed or configured by higher layer signaling. In one embodiment, the predetermined mapping establishes a correspondencebetween a second HARQ-ACK resource and a cardinality of the first set of subframes and the second HARQ-ACK resource is different from the first HARQ-ACK resource.

In one embodiment, an apparatus includes a receiver that receives a message indicating that a Physical Downlink Shared Channel ( “PDSCH” ) transport block ( “TB” ) is transmitted in a first set of subframes. In certain embodiments, the apparatus includes a processor that decodes the PDSCH TB in a second set of subframes. In such embodiments, the second set of subframes may be a proper subset of the first set of subframes. In various embodiments, the processor determines a first hybrid automatic repeat request acknowledgement (“HARQ-ACK” ) resource corresponding to the second set of subframes. The apparatus, in one embodiment, includes a transmitter that transmits a positive acknowledgement using the first HARQ-ACK resource. In certain embodiments, the positive acknowledgement may indicate that the PDSCH TB is correctly decoded from the second set of subframes.

In various embodiments, determining the first HARQ-ACK resource corresponding to the second set of subframes includes determining the first HARQ-ACK resource based on a predetermined mapping between the first HARQ-ACK resource and the second set of subframes. In one embodiment, the predetermined mapping between the first HARQ-ACK resource and the second set of subframes is fixed or configured by higher layer signaling. In certain embodiments, the predetermined mapping establishes a correspondencebetween a second HARQ-ACK resource and the first set of subframes and the second HARQ-ACK resource is different from the first HARQ-ACK resource. In some embodiments, the processor determines the first and second HARQ-ACK resources based on higher layer signaling.

In various embodiments, determining the first HARQ-ACK resource corresponding to the second set of subframes includes determining the first HARQ-ACK resource based on a predetermined mapping between the first HARQ-ACK resource and a cardinality of the second set of subframes. In one embodiment, the predetermined mapping between the first HARQ-ACK resource and the cardinality of the second set of subframes is fixed or configured by higher layer signaling. In certain embodiments, the predetermined mapping establishes a correspondencebetween a second HARQ-ACK resource and a cardinality of the first set of subframes and wherein the second HARQ-ACK resource is different from the first HARQ-ACK resource.

Another method for transmission repetition reduction, in one embodiment, includes receiving a message indicating thata Physical Downlink Shared Channel ( “PDSCH” ) transport block ( “TB” ) is transmitted in a first set of subframes. In some embodiments, the method includes decoding the PDSCH TB in a second set of subframes. In such embodiments, the second set of subframes may be a proper subset of the first set of subframes. In a further embodiment, the method includes determining a first hybrid automatic repeat request acknowledgement ( “HARQ-ACK” ) resource corresponding to the second set of subframes. In one embodiment, the method includes transmitting a positive acknowledgement using the first HARQ-ACK resource. In such an embodiment, the positive acknowledgement may indicate that the PDSCH TB is correctly decoded from the second set of subframes.

In some embodiments, determining the first HARQ-ACK resource corresponding to the second set of subframes includes determining the first HARQ-ACK resource based on a predetermined mapping between the first HARQ-ACK resource and the second set of subframes. In one embodiment, the predetermined mapping between the first HARQ-ACK resource and the second set of subframes is fixed or configured by higher layer signaling. In certain embodiments, the predetermined mapping establishes a correspondencebetween a second HARQ-ACK resource and the first set of subframes and the second HARQ-ACK resource is different from the first HARQ-ACK resource. In various embodiments, determining the first and second HARQ-ACK resources based on higher layer signaling.

In certain embodiments, determining the first HARQ-ACK resource corresponding to the second set of subframes includes determining the first HARQ-ACK resource based on a predetermined mapping between the first HARQ-ACK resource and a cardinality of the second set of subframes. In one embodiment, the predetermined mapping between the first HARQ-ACK resource and the cardinality of the second set of subframes is fixed or configured by higher layer signaling. In some embodiments, the predetermined mapping establishes a correspondencebetween a second HARQ-ACK resource and a cardinality of the first set of subframes and the second HARQ-ACK resource is different from the first HARQ-ACK resource.

BRIEF DESCRIPTION OF THE DRAWINGS

A more particular description of the embodiments briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings. Understanding that these drawings depict only some embodiments and are not therefore to be considered to be limiting of scope, the embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which:

Figure 1 is a schematic block diagram illustrating one embodiment of a wireless communication system for transmission repetition reduction；

Figure 2 is a schematic block diagram illustrating one embodiment of an apparatus that may be used for transmission repetition reduction；

Figure 3 is a schematic block diagram illustrating another embodiment of an apparatus that may be used for transmission repetition reduction；

Figure 4 illustrates one embodiment of uplink/downlink transmission that facilitatestransmission repetition reduction；

Figure 5 illustrates another embodiment of uplink/downlink transmission that facilitates transmission repetition reduction；

Figure 6 illustrates a further embodiment of uplink/downlink transmission that facilitates transmission repetition reduction；

Figure 7 illustrates an additional embodiment of uplink/downlink transmission that facilitates transmission repetition reduction；

Figure 8 is a schematic flow chart diagram illustrating one embodiment of a method for a base unit to transmitrepetitive transmissions to a remote unit and to receivefeedbackfrom the remote unit to reduce repetitive transmissions； and

Figure 9 is a schematic flow chart diagram illustrating one embodiment of a method for a remote unit to receive repetitive transmissions from a base unit and to transmitfeedback to the base unit to reduce repetitive transmissions.

DETAILED DESCRIPTION

As will be appreciated by one skilled in the art, aspects of the embodiments may be embodied as a system, apparatus, method, or program product. Accordingly, embodiments may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc. ) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit, ” “module” or “system. ” Furthermore, embodiments may take the form of a program product embodied in one or more computer readable storage devices storing machine readable code, computer readable code, and/or program code, referred hereafter as code. The storage devices may be tangible, non-transitory, and/or non-transmission. The storage devices may not embody signals. In a certain embodiment, the storage devices only employ signals for accessing code.

Certain of the functional units described in this specification may be labeled as modules, in order to more particularly emphasize their implementation independence. For example, a module may be implemented as a hardware circuit comprising custom very-large-scale integration ( “VLSI” ) circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like.

Modules may also be implemented in code and/or software for execution by various types of processors. An identified module of code may, for instance, include one or more physical or logical blocks of executable code which may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module need not be physically located together, but may include disparate instructions stored in different locations which, when joined logically together, include the module and achieve the stated purpose for the module.

Indeed, a module of code may be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within modules, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different computer readable storage devices. Where a module or portions of a module are implemented in software, the software portions are stored on one or more computer readable storage devices.

Any combination of one or more computer readable medium may be utilized. The computer readable mediummay be a computer readable storage medium. The computer readable storage medium may be a storage device storing the code. The storage device may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing.

More specific examples (a non-exhaustive list) of the storage device would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory ( “RAM” ) , a read-only memory ( “ROM” ) , an erasable programmable read-only memory ( “EPROM” or Flash memory) , a portable compact disc read-only memory ( “CD-ROM” ) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

Code for carrying out operations for embodiments may be any number of lines and may be written in any combination of one or more programming languagesincluding an object oriented programming language such as Python, Ruby, Java, Smalltalk, C++, or the like, and conventional procedural programming languages, such as the "C" programming language, or the like, and/or machine languages such as assembly languages. The code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network ( “LAN” ) or a wide area network (“WAN” ) , or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider) .

Reference throughout this specification to “one embodiment, ” “an embodiment, ” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in one embodiment, ” “in an embodiment, ” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment, but mean “one or more but not all embodiments” unless expressly specified otherwise. The terms “including, ” “comprising, ” “having, ” and variations thereof mean “including but not limited to, ” unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive, unless expressly specified otherwise. The terms “a, ” “an, ” and “the” also refer to “one or more” unless expressly specified otherwise.

Furthermore, the described features, structures, or characteristics of the embodiments may be combined in any suitable manner. In the following description, numerous specific details are provided, such as examples of programming, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., to provide a thorough understanding of embodiments. One skilled in the relevant art will recognize, however, that embodiments may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of an embodiment.

Aspects of the embodiments are described below with reference to schematic flowchart diagrams and/or schematic block diagrams of methods, apparatuses, systems, and program products according to embodiments. It will be understood that each block of the schematic flowchart diagrams and/or schematic block diagrams, and combinations of blocks in the schematic flowchart diagrams and/or schematic block diagrams, can be implemented by code. These code may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the schematic flowchart diagrams and/or schematic block diagrams block or blocks.

The code may also be stored in a storage device that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the storage device produce an article of manufacture including instructions which implement the function/act specified in the schematic flowchart diagrams and/or schematic block diagrams block or blocks.

The code may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the code which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

The schematic flowchart diagrams and/or schematic block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of apparatuses, systems, methods and program products according to various embodiments. In this regard, each block in the schematic flowchart diagrams and/or schematic block diagrams may represent a module, segment, or portion of code, which includes one or more executable instructions of the code for implementing the specified logical function (s) .

It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the Figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more blocks, or portions thereof, of the illustrated Figures.

Although various arrow types and line types may be employed in the flowchart and/or block diagrams, they are understood not to limit the scope of the corresponding embodiments. Indeed, some arrows or other connectors may be used to indicate only the logical flow of the depicted embodiment. For instance, an arrow may indicate a waiting or monitoring period of unspecified duration between enumerated steps of the depicted embodiment. It will also be noted that each block of the block diagrams and/or flowchart diagrams, and combinations of blocks in the block diagrams and/or flowchart diagrams, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and code.

The description of elements in each figure may refer to elements of proceeding figures. Like numbers refer to like elements in all figures, including alternate embodiments of like elements.

Figure 1 depicts an embodiment of a wireless communication system 100 for transmission repetition reduction. In one embodiment, the wireless communication system 100 includes remote units 102 and base units 104. Even though a specific number of remote units 102 and base units 104 are depicted in Figure 1, one of skill in the art will recognize that any number of remote units 102 and base units 104 may be included in the wireless communication system 100.

In one embodiment, the remote units 102 may include computing devices, such as desktop computers, laptop computers, personal digital assistants ( “PDAs” ) , tablet computers, smart phones, smart televisions (e.g., televisions connected to the Internet) , set-top boxes, game consoles, security systems (including security cameras) , vehicle on-board computers, network devices (e.g., routers, switches, modems) , MTCs, eMTCs, or the like. In some embodiments, the remote units 102 include wearable devices, such as smart watches, fitness bands, optical head-mounted displays, or the like. Moreover, the remote units 102 may be referred to as subscriber units, mobiles, mobile stations, users, terminals, mobile terminals, fixed terminals, subscriber stations, UE, user terminals, MTCs, eMTCs, or by other terminology used in the art. The remote units 102 may communicate directly with one or more of the base units 104 via UL communication signals.

The base units 104 may be distributed over a geographic region. In certain embodiments, a base unit 104 may also be referred to as an access point, an access terminal, a base, a base station, a Node-B, an eNB, a Home Node-B, a relay node, or by any other terminology used in the art. The base units 104 are generally part of a radio access network that includes one or more controllers communicably coupled to one or more corresponding base units 104. The radio access network is generally communicably coupled to one or more core networks, which may be coupled to other networks, like the Internet and public switched telephone networks, among other networks. These and other elements of radio access and core networks are not illustrated but are well known generally by those having ordinary skill in the art.

In one implementation, the wireless communication system 100 is compliant with the LTE of the 3GPP protocol, wherein the base unit 104 transmits using an OFDM modulation scheme on the DL and the remote units 102 transmit on the UL using a SC-FDMA scheme. More generally, however, the wireless communication system 100 may implement some other open or proprietary communication protocol, for example, WiMAX, among other protocols. The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol.

The base units 104 may serve a number of remote units 102 within a serving area, for example, a cell or a cell sector via a wireless communication link. The base units 104 transmit DL communication signals to serve the remote units 102 in the time, frequency, and/or spatial domain.

In one embodiment, abase unit 104 maytransmit a PDSCHTB in a first set of subframes to a remote unit 102. In such an embodiment, a second set of subframes is a proper subset of the first set of subframes. As may be appreciated, a “proper subset” of a set A is a subset of A that is not equal to A. In other words, if B is a proper subset of A, then all elements of B are in A but A contains at least one element that is not in B. The remote unit102 may receive a message indicating that the PDSCHTB is transmitted in the first set of subframes. Moreover, the remote unit 102may decode the PDSCH TB in the second set of subframes. In addition, the remote unit 102 may determinea first HARQ-ACK resource corresponding to the second set of subframes. The remote unit 102 may transmit a positive acknowledgement using the first HARQ-ACK resource. In certain embodiments, the positive acknowledgement indicates that the PDSCH TB is correctly decoded from the second set of subframes. Moreover, in some embodiments, the base unit 104 may receive the positive acknowledgement from the remote unit 102 using the first HARQ-ACK resource. In addition, the base unit 104 may determine a correspondence between the first HARQ-ACK resource and the second set of subframes.

Figure 2 depicts one embodiment of an apparatus 200 that may be used for transmission repetition reduction. The apparatus 200 includes one embodiment of the remote unit 102. Furthermore, the remote unit 102 may include a processor 202, a memory 204, an input device 206, a display 208, a transmitter 210, and a receiver 212. In some embodiments, the input device 206 and the display 208 are combined into a single device, such as a touchscreen. In certain embodiments, the remote unit 102 may not include any input device 206 and/or display 208. For example, in embodiments in which the remote unit 102 is an MTC or an eMTC, the remote unit 102 may function as UE without including other components of a UE. In such embodiments, the remote unit 102 may include one or more of the processor 202, the memory 204, the transmitter 210, and the receiver 212, and may not include the input device 206 and/or the display 208.

Theprocessor 202, in one embodiment, may include any known controller capable of executing computer-readable instructions and/or capable of performing logical operations. For example, the processor 202 may be a microcontroller, a microprocessor, a central processing unit ( “CPU” ) , a graphics processing unit ( “GPU” ) , an auxiliary processing unit, a field programmable gate array ( “FPGA” ) , or similar programmable controller. In some embodiments, the processor 202 executes instructions stored in the memory 204 to perform the methods and routines described herein. The processor 202 is communicatively coupled to the memory 204, the input device 206, the display 208, the transmitter 210, and the receiver 212.

The memory 204, in one embodiment, is a computer readable storage medium. In some embodiments, the memory 204 includes volatile computer storage media. For example, the memory 204 may include a RAM, including dynamic RAM ( “DRAM” ) , synchronous dynamic RAM ( “SDRAM” ) , and/or static RAM ( “SRAM” ) . In some embodiments, the memory 204 includes non-volatile computer storage media. For example, the memory 204 may include a hard disk drive, a flash memory, or any other suitable non-volatile computer storage device. In some embodiments, the memory 204 includes both volatile and non-volatile computer storage media. In some embodiments, the memory 204 stores data relating to HARQ-ACK resource allocation. In some embodiments, the memory 204 also stores program code and related data, such as an operating system or other controller algorithms operating on the remote unit 102.

The input device 206, in one embodiment, may include any known computer input device including a touch panel, a button, a keyboard, a stylus, a microphone, or the like. In some embodiments, the input device 206 may be integrated with the display 208, for example, as a touchscreen or similar touch-sensitive display. In some embodiments, the input device 206includes a touchscreen such that text may be input using a virtual keyboard displayed on the touchscreen and/or by handwriting on the touchscreen. In some embodiments, the input device 206includes two or more different devices, such as a keyboard and a touch panel.

The display 208, in one embodiment, may include any known electronically controllable display or display device. The display 208 may bedesigned to output visual, audible, and/or haptic signals. In some embodiments, the display 208 includes an electronic display capable of outputting visual data to a user. For example, the display 208 may include, but is not limited to, an LCD display, an LED display, an OLED display, a projector, or similar display device capable of outputting images, text, or the like to a user. As another, non-limiting, example, the display 208 may include a wearable display such as a smart watch, smart glasses, a heads-up display, or the like. Further, the display 208 may be a component of a smart phone, a personal digital assistant, a television, a table computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, or the like.

In certain embodiments, the display 208 includes one or more speakers for producing sound. For example, the display 208 may produce an audible alert or notification (e.g., a beep or chime) . In some embodiments, the display 208 includes one or more haptic devices for producing vibrations, motion, or other haptic feedback. In some embodiments, all or portions of the display 208 may be integrated with the input device 206. For example, the input device 206 and display 208 may form a touchscreen or similar touch-sensitive display. In other embodiments, the display 208 may be located near the input device 206.

The transmitter 210 is used to provide UL communication signals to the base unit 104 and the receiver 212 is used to receive DL communication signals from the base unit 104. In one embodiment, the transmitter 210 is used to transmit a positive acknowledgement using a HARQ-ACK resource. In another embodiment, the receiver 212 may receive a message from the base unit 104 indicating that a PDSCH TB is transmitted in a first set of subframes. Although only one transmitter 210 and one receiver 212 are illustrated, the remote unit 102 may have any suitable number of transmitters 210 and receivers 212. The transmitter 210 and the receiver 212 may be any suitable type of transmitters and receivers. In one embodiment, the transmitter 210 and the receiver 212 may be part of a transceiver.

Figure 3 depicts another embodiment of an apparatus 300 that may be used for transmission repetition reduction. The apparatus 300 includes one embodiment of the base unit 104. Furthermore, the base unit 104 may include a processor 302, a memory 304, an input device 306, a display 308, a transmitter 310, and a receiver 312. As may be appreciated, the processor 302, the memory 304, the input device 306, and the display 308 may be substantially similar to the processor 202, the memory 204, the input device 206, and the display 208 of the remote unit 102, respectively.

The transmitter 310 is used to provide DL communication signals to the remote unit 102 and the receiver 312 is used to receive UL communication signals from the remote unit 102. In one embodiment, the transmitter 310 is used to transmit a PDSCH TB in a first set of subframes to the remote unit 102 (e.g., device) . In another embodiment, the receiver 312 is used to receive a positive acknowledgement from the remote unit 102 using a HARQ-ACK resource. Although only one transmitter 310 and one receiver 312 are illustrated, the base unit 104 may have any suitable number of transmitters 310 and receivers 312. The transmitter 310 and the receiver 312 may be any suitable type of transmitters and receivers. In one embodiment, the transmitter 310 and the receiver 312 may be part of a transceiver.

Figures 4 through 7 depict various embodiments of uplink/downlink transmissions that facilitate transmission repetition reduction. Such embodiments are examples illustrating how a remote unit 102 may provide feedback to a base unit 104 that it is able to successfully decode the PDSCH using a smaller number of repetitions than the base unit 104 allocates. In certain embodiments, this may be called the early termination of PDSCH decoding. With the early termination indication from an eMTC remote unit 102, the base unit 104may adjust the number of PDSCH repetitions when scheduling the future PDSCH transmission to the remote unit 102.

Using early termination indication may result in more efficient resource utilization for DL transmission. Furthermore, providing an early termination indication as described in the following examples may be performed without significantly increasing power consumption of the remote unit 102. In certain embodiments, the base unit 104 may use the early termination indication reported by the remote unit 102 to adjust the number of PDSCH repetitions in the future PDSCH transmission such that the time-frequency resource is used more efficiently. In other embodiments, the remote unit 102 may send an early termination indication to the base unit 102 (or the network) without significantly increase its power consumption as compared to the remote unit 102 in which the remote unit 102 does not transmit the early termination indication to the base unit 102.

As may be appreciated, a HARQ ACK/NACK istransmitted from the remote unit 102 to the base unit 104 after reception of the PDSCH. As described herein, the early termination indication may be transmitted to the base unit 104 together with the HARQ ACK/NACK feedback without significantly increasing the power consumption of the remote unit 102 as compared to a remote unit 102 that does not transmit the early termination indication.

In coverage enhancement, HARQ ACK/NACK for PDSCH may be repeated. In one embodiment, the repetition number of HARQ ACK/NACK is configured by higher layer signaling, such as RRC. In certain embodiments, the repetition number of HARQ ACK/NACK is tied to the repetition number of M-PDCCH. In other embodiments, the repetition number of HARQ ACK/NACK is tied to the repetition number of PDSCH. However, in any repetition scheme for HARQ ACK/NACK, the base unit 104 and the remote unit 102 have a common knowledge on the set of subframes used for ACK/NACK repetition by the remote unit 102.

A PDSCH decoding attempt may be defined to aid the base unit 104 in understanding early termination information. For example, a PDSCH decoding attempt may be defined to be the number repetitions that a remote unit 102 uses when decoding a PDSCH TB. Each PDSCH decoding attempt may correspond to a unique number of repetitions that a remote unit 102 uses to decode a PDSCH TB. For instance, assume that the number of PDSCH decoding attempts is M, the first PDSCH decoding attempt includes L PDSCH repetitions, and the last PDSCH decoding attempt includes N PDSCH repetitions. In certain embodiments, N may be indicated to the remote unit 102 by the DCI. In some embodiments, the remote unit 102 may know the values of L and M via high layer signaling, such as via RRC, or the values of L and M may be predetermined, such as via a specification. If the number of PDSCH repetitions in the remaining M-2 PDSCH decoding attempts are evenly spaced between L and N, each of the M PDSCH decoding attempts shall include P number of PDSCH repetitions, where P can be described by:

where i＝0， 1， 2， ...， M-1

With all three values (L, M, N) known to both the base unit 104 and the remote unit 102, then the remote unit 102 may perform multiple PDSCH decoding attempts and send information corresponding to an actually required PDSCH repetition number back to the base unit 104.

For example, if the DCI indicates that a following PDSCH will repeat N times, L is set to

and the PDSCH decoding attempt number M is set to 2, an eMTC remote unit 102may first receive

repetitions and try to decode the data. If the eMTC remote unit 102 cannot decode the data correctly then the eMTC remote unit 102 may receive all the repetitions to perform the decoding. If an eMTC remote unit 102 can decode the PDSCH TB correctly using a PDSCH decoding attempt with the repetition number less than N, the remote unit 102 may indicate the corresponding PDSCH decoding attempt information to the base unit 104. As may be appreciated, in certain embodiments, the remote unit 102 may provide the PDSCH decoding attempt information to the base unit 104 together with the HARQ-ACK feedback, such as by using the embodiments described in Figures 4 through 7.

As may be appreciated, in certain embodiments, the M PDSCH decoding attempts may be defined in a different way than described above as long as there is a common understanding between the base unit 104 and the remote unit 102 regarding the number of PDSCH repetitions for each of the M PDSCH decoding attempts. In one embodiment, a set of coefficients may be configured by higher layers signaling such as RRC or fixed via a specification, wherein each of the coefficients is associated with a PDSCH decoding attempt. The number of subframes in a PDSCH decoding attempt is the product of the associated coefficient and the maximum number of repetitions for a PDSCH TB. In one embodiment, the maximum number of repetitions of a PDSCH TB may be included in the DL grant scheduling the PDSCH TB. In another embodiment, the maximum number of repetitions for a PDSCH TB is configured by higher layers signaling such as RRC.

Figure 4 depicts one embodiment of uplink/downlink transmission 400 that facilitates transmission repetition reduction. The uplink/downlink transmission 400 includes a DL transmission 402 and a UL transmission 404. In the illustrated embodiment, both of the DL transmission 402 and the UL transmission 404 may include six PRBs, while in other embodiments the DL transmission 402 and the UL transmission 404 may include any suitable number of PRBs.

Each rectangle 406 within the DL transmission 402 represents one subframe. Furthermore, there are N repetitions of PDSCH 408. In the illustrated embodiment, the number of PDSCH decoding attempts M is 2； however, in other embodiments, the number of PDSCH decoding attempts M may be any suitable number. Accordingly, the N repetitions of PDSCH 408 include a first decoding attempt 410 (e.g.,

) and a second decoding attempt 412 (e.g., N) . Each rectangle 414 within the UL transmission 404 also represents one subframe.

In certain embodiments, HARQ ACK/NACK is transmitted within the UL transmission 404 by PUCCH. In the illustrated embodiment, M HARQ-ACK resources (i.e., a first HARQ-ACK resource 416 and a second HARQ-ACK resource 418) are derived by the eMTC remote unit 102 to transmit the PDSCH decoding attempt information and the HARQ-ACK information, where M denotes the number of PDSCH decoding attempts. As illustrated in Figure 4, the M HARQ-ACK resources may start from the same subframes in the time domain； however, as illustrated in Figure 5, the M HARQ-ACK resources may start from different subframes in the time domain. Irrespective of whether the starting subframe for the M HARQ-ACK resources is the same or different, the timing relationship between the starting subframe (s) of the M HARQ-ACK resources and the M PDSCH decoding attempts is determined based on a pre-determined rule, which can be fixed. In this way, both the base unit 104 and the remote unit 102 have a common understanding of the timing relationship between the starting subframe (s) of the M HARQ-ACK resources and the M PDSCH decoding attempts.

As illustrated, there is a 1-to-1 mapping between the M PDSCH decoding attempts and the M HARQ-ACK resources. Depending on the PDSCH decoding attempt in which the remote unit 102successfully decodes the PDSCH TB, the remote unit 102 selects the HARQ-ACK resource (i.e., the first HARQ-ACK resource 416, the second HARQ-ACK resource 418) corresponding to the PDSCH decoding attempt to transmit the HARQ-ACK bit. For example, if the remote unit 102 successfully decodes the PDSCH TB during the first decoding attempt 410 then the remote unit 102 selects the first HARQ-ACK resource 416 to transmit the HARQ-ACK bit. In such an example, the remote unit 102 may not transmit any signalusing the second HARQ-ACK resource 418. As another example, if the remote unit 102 successfully decodes the PDSCH TB during the second decoding attempt 412 then the remote unit 102 selects the second HARQ-ACK resource 418 to transmit the HARQ-ACK bit. In such an example, the remote unit 102 may not transmit any signal using the first HARQ-ACK resources 416. In one embodiment, the 1-to-1 mapping between the M PDSCH decoding attempts and the M HARQ-ACK resources is established by a predetermined rule. In one embodiment, the M PDSCH decoding attempts maybe ordered in an ascending order according to the number of repetitions in the PDSCH decoding attempt. The M HARQ-ACK resources maybe ordered in an ascending order according to the HARQ-ACK resource index. The 1-to-1 mapping between the M PDSCH decoding attempts and the M HARQ-ACK resources are established by mapping the n-th PDSCH decoding attempt to the n-th HARQ-ACK resource, where 1≤n≤M. Other methods to order the PDSCH decoding attempts and to order the HARQ-ACK resources are not precluded.

In certain embodiments, for any PDSCH decoding attempt other than the one with the maximum number of PDSCH repetitions, the corresponding ACK/NACK information shall always be ACK. In certain embodiments, for an eMTC remote unit 102, ACK/NACK may be just one bit of information. Furthermore, asset forth above, a maximum of 36 PUCCH Format 1a/1b resources can be carried in just one PRB. Therefore, assigning multiple HARQ-ACK resources to an eMTC remote unit 102 does not significantly increase the PUCCH overhead.

In various embodiments, the M HARQ-ACK resources may be determined based on a predetermined rule, such that the base unit 104 and the remote unit 102 have a common understanding on the M HARQ-ACK resources. In one embodiment, the M HARQ-ACK resources are configured by higher layers, such as via RRC signaling. In another embodiment, the M HARQ-ACK resources are determined based on a combination of higher layer signaling and physical layer signaling, i.e. a higher layer configures a set of HARQ-ACK resources and the physical layer signaling (e.g. the DL grant scheduling the PDSCH) indicates M HARQ-ACK resources among the set of higher layer configured HARQ-ACK resources. In yet another embodiment, the M HARQ-ACK resources are implicitly derived based on a CCE used to transmit the M-PDCCH carrying the DL grant scheduling the PDSCH.

The mapping between the M PDSCH decoding attempts and the M HARQ-ACK resources is determined based on a predetermined rule, which may be fixed or configured by higher layers via RRC signaling. In one embodiment, the mapping is between the M PDSCH decoding attempts and the M HARQ-ACK resources. In another embodiment, the mapping is between the cardinalities of the M PDSCH decoding attempts and the M HARQ-ACK resources. This is because the base unit 104 may not need to know the exact set of subframes contained in each of the PDSCH decoding attempts. Rather, the base unit 104 only needs to know the number of subframes contained in each of the PDSCH decoding attempt, based on which the base unit 104may adjust the number of subframes for transmission of a PDSCH TB in the future.

The base unit 104 detects which one of the M HARQ-ACK resources is used by the eMTC remote unit 102 and then derives the ACK/NACK information and indicated PDSCH decoding attempt information. In certain embodiments, it may be appreciated that the eNB may use the fact that only ACK can be transmitted on each of the M-1 HARQ-ACK resources corresponding to PDSCH decoding attempts other than the one with the maximum number of PDSCH repetitions.

Figure 5 illustrates another embodiment of uplink/downlink transmission 500 that facilitates transmission repetition reduction. The uplink/downlink transmission 500 includes a DL transmission 502 and a UL transmission 504. In the illustrated embodiment, both of the DL transmission 502 and the UL transmission 504 may include six PRBs, while in other embodiments the DL transmission 502 and the UL transmission 504 may include any suitable number of PRBs.

Each rectangle 506 within the DL transmission 502 represents one subframe. Furthermore, there are N repetitions of PDSCH 508. In the illustrated embodiment, the number of PDSCH decoding attempts M is 2； however, in other embodiments, the number of PDSCH decoding attempts M may be any suitable number. Accordingly, the N repetitions of PDSCH 508 include a first decoding attempt 510 (e.g.,

) and a second decoding attempt 512 (e.g., N) . Each rectangle 514 within the UL transmission 504 also represents one subframe.

In certain embodiments, HARQ ACK/NACK is transmitted within the UL transmission 504 by PUCCH. In the illustrated embodiment, M HARQ-ACK resources (i.e., a first HARQ-ACK resource 516 and a second HARQ-ACK resource 518) are derived by the eMTC remote unit 102 to transmit the PDSCH decoding attempt information and the HARQ-ACK information, where M denotes the number of PDSCH decoding attempts. As illustrated in Figure 5, the M HARQ-ACK resources may start from different subframes in the time domain； however, as illustrated in Figure 4, the M HARQ-ACK resources may start from the same subframes in the time domain. Irrespective of whether the starting subframe for the M HARQ-ACK resources is the same or different, the timing relationship between the starting subframe (s) of the M HARQ-ACK resources and the M PDSCH decoding attempts is determined based on a pre-determined rule, which can be fixed. In this way, both the base unit 104 and the remote unit 102 have a common understanding of the timing relationship between the starting subframe (s) of the M HARQ-ACK resources and the M PDSCH decoding attempts.

As illustrated, there is a 1-to-1 mapping between the M PDSCH decoding attempts and the M HARQ-ACK resources. Depending on the PDSCH decoding attempt in which the remote unit 102successfully decodes the PDSCH TB, the remote unit 102 selects the HARQ-ACK resource (i.e., the first HARQ-ACK resource516, the second HARQ-ACK resource518) corresponding to the PDSCH decoding attempt to transmit the HARQ-ACK bit. For example, if the remote unit 102 successfully decodes the PDSCH TB during the first decoding attempt 510 then the remote unit 102 selects the first HARQ-ACK resource516 to transmit the HARQ-ACK bit. In such an example, the remote unit 102 may not transmit any signalusing the second HARQ-ACK resource518. As another example, if the remote unit 102 successfully decodes the PDSCH TB during the second decoding attempt 512 then the remote unit 102 selects the second HARQ-ACK resource 518 to transmit the HARQ-ACK bit. In such an example, the remote unit 102 may not transmit any signal on the first HARQ-ACK resources 516. In one embodiment, the 1-to-1 mapping between the M PDSCH decoding attempts and the M HARQ-ACK resources is established by a predetermined rule. In one embodiment, the M PDSCH decoding attempts may be ordered in an ascending order according to the number of repetitions in the PDSCH decoding attempt. The M HARQ-ACK resources may be ordered in an ascending order according to the HARQ-ACK resource index. The 1-to-1 mapping between the M PDSCH decoding attempts and the M HARQ-ACK resources are established by mapping the n-th PDSCH decoding attempt to the n-th HARQ-ACK resource, where 1≤n≤M. Other methods to order the PDSCH decoding attempts and to order the HARQ-ACK resources are not precluded.

In certain embodiments, for any PDSCH decoding attempt other than the one with the maximum number of PDSCH repetitions, the corresponding ACK/NACK information shall always be ACK. In certain embodiments, for an eMTC remote unit 102, ACK/NACK may be just one bit of information. Furthermore, as set forth above, a maximum of 36 PUCCH Format 1a/1b resources can be carried in just one PRB. Therefore, assigning multiple HARQ-ACK resources to an eMTC remote unit 102 does not significantly increase the PUCCH overhead.

Figure 6 illustrates a further embodiment of uplink/downlink transmission 600 that facilitates transmission repetition reduction. The uplink/downlink transmission 600 includes a DL transmission 602 and a UL transmission 604. In the illustrated embodiment, both of the DL transmission 602 and the UL transmission 604 may include six PRBs, while in other embodiments the DL transmission 602 and the UL transmission 604 may include any suitable number of PRBs.

Each rectangle 606 within the DL transmission 602 represents one subframe. Furthermore, there are N repetitions of PDSCH 608. In the illustrated embodiment, the number of PDSCH decoding attempts M is 2； however, in other embodiments, the number of PDSCH decoding attempts M may be any suitable number. Accordingly, the N repetitions of PDSCH 608 include a first decoding attempt 610 (e.g.,

) and a second decoding attempt 612 (e.g., N) . Each rectangle 614 within the UL transmission 604 also represents one subframe.

In the illustrated embodiment, only one HARQ-ACK resource 616 is derived by the eMTC remote unit 102 to transmit the PDSCH decoding attempt information and the HARQ-ACK information. In certain embodiments, the HARQ-ACK resource 616 may be similar to one of the HARQ-ACK resources described in Figures 4 and 5 (e.g., the first and second HARQ-ACK resources 416 and 418, the first and second HARQ-ACK resources 516 and 518) . The HARQ-ACK resource 616 is used for transmission in a first number of subframes 618 (e.g.,

)or in a second number of subframes 620 (e.g., A) . There is a 1-to-1 mapping between the M PDSCH decoding attempts (i.e., the first and second decoding attempts 610 and 612) and the different number subframes used for the transmission of the HARQ-ACK resource (i.e., the first and second numbers of subframes 618 and 620) . Depending on the PDSCH decoding attempt in which the remote unit 102successfully decodes the PDSCH TB, the remote unit 102 selects the different number of subframes used for the transmission of the HARQ-ACK resource (i.e., the first number of subframes 618, the second number of subframes) . The HARQ-ACK resource is used to convey the ACK/NACK information.

For example, if the remote unit 102 successfully decodes the PDSCH TB during the first decoding attempt 610 then the remote unit 102 selects the first number of subframes 618 to transmit the HARQ-ACK bit. In such an example, the remote unit 102 may not transmit any signalon the HARQ-ACK resource inthe subframes that are part of the second number of subframes 620 and not part of the first number of subframes 618. As another example, if the remote unit 102 successfully decodes the PDSCH TB during the second decoding attempt 612 then the remote unit 102 selects the second number of subframes 620 to transmit the HARQ-ACK bit.

It is noted that for any PDSCH decoding attempt other than the one with the maximum number of PDSCH repetitions, the corresponding ACK/NACK information shall always be ACK. As mentioned previously, the ACK/NACK repetition number may be tied to either M-PDCCH or PDSCH repetition, so the ACK/NACK repetition may be reduced according to the PDSCH decoding attempt.

The base unit 104 detects how many subframes the eMTC remote unit 102 uses for the transmission of the HARQ-ACK resource and then derives the ACK/NACK information and indicated PDSCH decoding attempt information. It should be noted that the base unit 104 may use the fact that only ACK can be transmitted on each of the M-1 (M is the total PDSCH decoding attempt number) possibilities of different subframes used for the transmission of the HARQ-ACK resource corresponding to PDSCH decoding attempts other than the one with the maximum number of PDSCH repetitions.

Figure 7 illustrates an additional embodiment of uplink/downlink transmission 700 that facilitates transmission repetition reduction. The uplink/downlink transmission 700 includes a DL transmission 702 and a UL transmission 704. In the illustrated embodiment, both of the DL transmission 702 and the UL transmission 704 may include six PRBs, while in other embodiments the DL transmission 702 and the UL transmission 704 may include any suitable number of PRBs.

Each rectangle 706 within the DL transmission 702 represents one subframe. Furthermore, there are N repetitions of PDSCH 708. In the illustrated embodiment, the number of PDSCH decoding attempts M is 4； however, in other embodiments, the number of PDSCH decoding attempts M may be any suitable number. Accordingly, the N repetitions of PDSCH 708 include a first decoding attempt 710 (e.g.,

) , a second decoding attempt 712 (e.g.,

) , a third decoding attempt 714 (e.g.,

) , and a fourth decoding attempt 716 (e.g., N) . Each rectangle 718 within the UL transmission 704 also represents one subframe.

The embodiment of Figure 7 is one representation of a combination of the embodiments of Figure 4 and Figure 6. In the embodiment illustrated in Figure 7, R (R < M, M is the PDSCH decoding attempt number) HARQ-ACK resources are derived by the eMTC remote unit 102 to transmit the PDSCH decoding attempt information and the HARQ-ACK information. In one embodiment, M＝4 and R＝2； however, any suitable values for M and R may be used.

In the illustrated embodiment, twoHARQ-ACK resources (i.e., a first HARQ-ACK resource720 and a second HARQ-ACK resource 722) arederived by the eMTC remote unit 102 to transmit the PDSCH decoding attempt information and the HARQ-ACK information. In certain embodiments, the first and second HARQ-ACK resources 720 and 722 may be similar to the HARQ-ACK resources described in Figures 4 and 5 (e.g., the first and second HARQ-ACK resources 416 and 418, the first and second HARQ-ACK resources 516 and 518) . Each of the first and second HARQ-ACK resources 720 and 722is used for transmission in a first number of subframes 724 (e.g.,

) or in a second number of subframes 726 (e.g., A) . There is a 1-to-1 mapping between the M PDSCH decoding attempts (i.e., the first, second, third, and fourth decoding attempts 710, 712, 714, and 716) and the combinations of different HARQ-ACK resources and different number of subframes used for transmission of the HARQ-ACK resource. Depending on the PDSCH decoding attempt in which the remote unit 102successfully decodes the PDSCH TB, the remote unit 102 selects one of corresponding combination to transmit the HARQ-ACK bit. It should be noted that for any PDSCH decoding attempt other than the ones with the maximum number of PDSCH repetitions, the corresponding ACK/NACK information shall always be ACK.

For example, if the remote unit 102 successfully decodes the PDSCH TB during the first decoding attempt 710 then the remote unit 102 selects the first number of subframes 724and the first HARQ-ACK resource720 to transmit the HARQ-ACK bit. As another example, if the remote unit 102 successfully decodes the PDSCH TB during the second decoding attempt 712 then the remote unit 102 selects the firstnumber of subframes 724and the second HARQ-ACK resource 722 to transmit the HARQ-ACK bit. As a further example, if the remote unit 102 successfully decodes the PDSCH TB during the third decoding attempt 714 then the remote unit 102 selects the secondnumber of subframes 726andthe first HARQ-ACK resource 720 to transmit the HARQ-ACK bit. Moreover, as another example, if the remote unit 102 successfully decodes the PDSCH TB during the fourth decoding attempt 716 then the remote unit 102 selects the second number of subframes 726andthe second HARQ-ACK resource 722 to transmit the HARQ-ACK bit.

The base unit 104 detects which combination of different subframes and different HARQ-ACK resources are used by the eMTC remote unit 102 and then derive the ACK/NACK information and indicated PDSCH decoding attempt information. It should be noted that the base unit 104 may use the fact that only ACK can be transmitted on each of the M-1 combinations corresponding to PDSCH decoding attempts other than the one with the maximum number of PDSCH repetitions.

Although the implicit indication of required PDSCH repetition number by ACK/NACK is feasible according to the above embodiments of Figure 4 through Figure 7, certain embodiments may add one or more bits to legacy PUCCH Format 1a/1b to report the PDSCH decoding attempt information explicitly. For example, PUCCH Format 1bcould carry two bits of information. One bit may be used to indicate the ACK/NACK while the other bit may be used to indicate a binary possibility of a PDSCH decoding attempt. In such an embodiment, the base unit 104 mayuse the signal transmitted on onePUCCH Format 1b resource and get both the ACK/NACK information and the indicated PDSCH decoding attempt information.

Figure 8 is a schematic flow chart diagram illustrating one embodiment of a method 800 for a base unit 104 to transmit repetitive transmissions to a remote unit 102 and to receive feedback from the remote unit 102 to reduce repetitive transmissions. In some embodiments, the method 800 is performed by an apparatus, such as the base unit 104. In certain embodiments, the method 800 may be performed by a processor executing program code, for example, a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like.

The method 800 may include transmitting 802 a PDSCH TB in a first set of subframes to a device (e.g., a remote unit 102) . In certain embodiments, the base unit 104 may transmit 802 the PDSCH TB in the first set of subframes to the device. The method 800 may also include receiving 804 a positive acknowledgement from the device using a firstHARQ-ACK resource. In certain embodiments, the base unit 104 may receive 804 the positive acknowledgement from the device using the firstHARQ-ACK resource. In some embodiments, the positive acknowledgement indicates that the PDSCH TB is correctly decoded from the second set of subframes.

The method 800 may include determining 806 a correspondence between the first HARQ-ACK resource and a second set of subframes. Then the method 800 may end. In one embodiment, a second set of subframes is a proper subset of the first set of subframes. In some embodiments, the base unit 104 may determine 806 the correspondence between the first HARQ-ACK resource and the second set of subframes. In certain embodiments, determining 806 the correspondence between the first HARQ-ACK resource and the second set of subframes includes determining the correspondence between the first HARQ-ACK resource and the second set of subframes based on a predetermined mapping between the first HARQ-ACK resource and the second set of subframes. Moreover, in some embodiments, the predetermined mapping between the HARQ-ACK resource and the second set of subframes is fixed (e.g., predefined) or configured by higher layer signaling (e.g., RRC) . In various embodiments, the predetermined mapping establishes a correspondencebetween a second HARQ-ACK resource and the first set of subframes. In such embodiments, the second HARQ-ACK resource is different from the first HARQ-ACK resource.

In one embodiment, determining 806 the correspondence between the first HARQ-ACK resource and the second set of subframes includes determining the correspondence between the first HARQ-ACK resource and the second set of subframes based on a predetermined mapping between the first HARQ-ACK resource and a cardinality of the second set of subframes. Moreover, in some embodiments, the predetermined mapping between the first HARQ-ACK resource and the cardinality of the second set of subframes is fixed or configured by higher layer signaling. In various embodiments, the predetermined mapping establishes a correspondencebetween a second HARQ-ACK resource and a cardinality of the first set of subframes. In such embodiments, the second HARQ-ACK resource is different from the first HARQ-ACK resource.

Figure 9is a schematic flow chart diagram illustrating one embodiment of a method 900 for a remote unit 102 to receive repetitive transmissions from a base unit 104 and to transmit feedback to the base unit 104 to reduce repetitive transmissions. In some embodiments, the method 900 is performed by an apparatus, such as the remote unit 102. In certain embodiments, the method 900 may be performed by a processor executing program code, for example, a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like.

The method 900 may include receiving 902 a message indicating that a PDSCH TB is transmitted in a first set of subframes. In one embodiment, the receiver 212 of the remote unit 102 may receive 902 the message indicating that the PDSCH TB is transmitted in the first set of subframes. The method 900 may also include decoding 904 the PDSCH TB in a second set of subframes. In certain embodiments, the second set of subframes is a proper subset of the first set of subframes. In some embodiments, the remote unit 102 may decode 904 the PDSCH TB in the second set of subframes.

The method 900 may include determining 906 a first HARQ-ACK resource corresponding to the second set of subframes. In certain embodiments, the remote unit 102 may determine 906 the first HARQ-ACK resource corresponding to the second set of subframes. In one embodiment, determining 906 the first HARQ-ACK resource corresponding to the second set of subframes includes determining the first HARQ-ACK resource based on a predetermined mapping between the first HARQ-ACK resource and the second set of subframes. In some embodiments, the predetermined mapping between the first HARQ-ACK resource and the second set of subframes is fixed (e.g., predefined) or configured by higher layer signaling (e.g., RRC) . In one embodiment, the predetermined mapping establishes a correspondencebetween a second HARQ-ACK resource and the first set of subframes. In such an embodiment, the second HARQ-ACK resource is different from the first HARQ-ACK resource. In some embodiments, the method 900 includes determining the first and second HARQ-ACK resources based on higher layer signaling.

In certain embodiments, determining 906 the first HARQ-ACK resource corresponding to the second set of subframes includes determining the first HARQ-ACK resource based on a predetermined mapping between the first HARQ-ACK resource and a cardinality of the second set of subframes. In one embodiment, the predetermined mapping between the first HARQ-ACK resource and the cardinality of the second set of subframes is fixed or configured by higher layer signaling. In some embodiments, the predetermined mapping establishes a correspondencebetween a second HARQ-ACK resource and a cardinality of the first set of subframes. In such embodiments, the second HARQ-ACK resource is different from the first HARQ-ACK resource.

The method 900 may include transmitting 908 a positive acknowledgement using the first HARQ-ACK resource. Then the method 900 may end. In certain embodiments, the transmitter 210 of the remote unit 102 may transmit 908 the positive acknowledgement using the first HARQ-ACK resource. In some embodiments, the positive acknowledgement indicates that the PDSCH TB is correctly decoded from the second set of subframes.

Embodiments may be practiced in other specific forms. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

An apparatus comprising:

a transmitter that transmits a Physical Downlink Shared Channel ( “PDSCH” ) transport block ( “TB” ) in a first set of subframes to a device, wherein a second set of subframes is a proper subset of the first set of subframes；

a receiver that receives a positive acknowledgement from the device using a first hybrid automatic repeat request acknowledgement ( “HARQ-ACK” ) resource, wherein the positive acknowledgement indicates that the PDSCH TB is correctly decoded from the second set of subframes； and

a processor that determines a correspondence between the first HARQ-ACK resource and the second set of subframes.
The apparatus of claim 1, wherein the processor that determines the correspondence between the first HARQ-ACK resource and the second set of subframes further determines the correspondence between the first HARQ-ACK resource and the second set of subframes based on a predetermined mapping between the first HARQ-ACK resource and the second set of subframes.
The apparatus of claim 2, wherein the predetermined mapping between the first HARQ-ACK resource and the second set of subframes is fixed or configured by higher layer signaling.
The apparatus of claim 2, wherein the predetermined mapping establishes a correspondence between a second HARQ-ACK resource and the first set of subframes and wherein the second HARQ-ACK resource is different from the first HARQ-ACK resource.
The apparatus of claim 1, wherein the processor that determines the correspondence between the first HARQ-ACK resource and the second set of subframes further determines the correspondence between the first HARQ-ACK resource and the second set of subframes based on a predetermined mapping between the first HARQ-ACK resource and a cardinality of the second set of subframes.
The apparatus of claim 5, wherein the predetermined mapping between the first HARQ-ACK resource and the cardinality of the second set of subframes is fixed or configured by higher layer signaling.
The apparatus of claim 5, wherein the predetermined mapping establishes a correspondence between a second HARQ-ACK resource and a cardinality of the first set of subframes and wherein the second HARQ-ACK resource is different from the first HARQ-ACK resource.
A method comprising:

transmitting a Physical Downlink Shared Channel ( “PDSCH” ) transport block ( “TB” ) in a first set of subframes to a device, wherein a second set of subframes is a proper subset of the first set of subframes；

receiving a positive acknowledgement from the device using a first hybrid automatic repeat request acknowledgement ( “HARQ-ACK” ) resource, wherein the positive acknowledgement indicates that the PDSCH TB is correctly decoded from the second set of subframes； and

determining a correspondence between the first HARQ-ACK resource and the second set of subframes.
The method of claim 8, wherein determining the correspondence between the first HARQ-ACK resource and the second set of subframes comprises determining the correspondence between the first HARQ-ACK resource and the second set of subframes based on a predetermined mapping between the first HARQ-ACK resource and the second set of subframes.
The method of claim 9, wherein the predetermined mapping between the HARQ-ACK resource and the second set of subframes is fixed or configured by higher layer signaling.
The method of claim 9, wherein the predetermined mapping establishes a correspondence between a second HARQ-ACK resource and the first set of subframes and wherein the second HARQ-ACK resource is different from the first HARQ-ACK resource.
The method of claim 8, wherein determining the correspondence between the first HARQ-ACK resource and the second set of subframes comprises determining the correspondence between the first HARQ-ACK resource and the second set of subframes based on a predetermined mapping between the first HARQ-ACK resource and a cardinality of the second set of subframes.
The method of claim 12, wherein the predetermined mapping between the first HARQ-ACK resource and the cardinality of the second set of subframes is fixed or configured by higher layer signaling.
The method of claim 12, wherein the predetermined mapping establishes a correspondence between a second HARQ-ACK resource and a cardinality of the first set of subframes and wherein the second HARQ-ACK resource is different from the first HARQ-ACK resource.
An apparatus comprising:

a receiver that receives a message indicating that a Physical Downlink Shared Channel ( “PDSCH” ) transport block ( “TB” ) is transmitted in a first set of subframes；

a processor that:

decodes the PDSCH TB in a second set of subframes, wherein the second set of subframes is a proper subset of the first set of subframes； and

determines a first hybrid automatic repeat request acknowledgement ( “HARQ-ACK” ) resource corresponding to the second set of subframes； and

a transmitter that transmits a positive acknowledgement using the first HARQ-ACK resource, wherein the positive acknowledgement indicates that the PDSCH TB is correctly decoded from the second set of subframes.
The apparatus of claim 15, wherein determining the first HARQ-ACK resource corresponding to the second set of subframes comprises determining the first HARQ-ACK resource based on a predetermined mapping between the first HARQ-ACK resource and the second set of subframes.
The apparatus of claim 16, wherein the predetermined mapping between the first HARQ-ACK resource and the second set of subframes is fixed or configured by higher layer signaling.
The apparatus of claim 16, wherein the predetermined mapping establishes a correspondence between a second HARQ-ACK resource and the first set of subframes and wherein the second HARQ-ACK resource is different from the first HARQ-ACK resource.
The apparatus of claim 18, wherein the processor determines the first and second HARQ-ACK resources based on higher layer signaling.
The apparatus of claim 15, wherein determining the first HARQ-ACK resource corresponding to the second set of subframes comprises determining the first HARQ-ACK resource based on a predetermined mapping between the first HARQ-ACK resource and a cardinality of the second set of subframes.
The apparatus of claim 20, wherein the predetermined mapping between the first HARQ-ACK resource and the cardinality of the second set of subframes is fixed or configured by higher layer signaling.
The apparatus of claim 20, wherein the predetermined mapping establishes a correspondence between a second HARQ-ACK resource and a cardinality of the first set of subframes and wherein the second HARQ-ACK resource is different from the first HARQ-ACK resource.
A method comprising:

receiving a message indicating that a Physical Downlink Shared Channel ( “PDSCH” ) transport block ( “TB” ) is transmitted in a first set of subframes；

decoding the PDSCH TB in a second set of subframes, wherein the second set of subframes is a proper subset of the first set of subframes；

determining a first hybrid automatic repeat request acknowledgement ( “HARQ-ACK” ) resource corresponding to the second set of subframes； and

transmitting a positive acknowledgement using the first HARQ-ACK resource, wherein the positive acknowledgement indicates that the PDSCH TB is correctly decoded from the second set of subframes.
The method of claim 23, wherein determining the first HARQ-ACK resource corresponding to the second set of subframes comprises determining the first HARQ-ACK resource based on a predetermined mapping between the first HARQ-ACK resource and the second set of subframes.
The method of claim 24, wherein the predetermined mapping between the first HARQ-ACK resource and the second set of subframes is fixed or configured by higher layer signaling.
The method of claim 24, wherein the predetermined mapping establishes a correspondence between a second HARQ-ACK resource and the first set of subframes and wherein the second HARQ-ACK resource is different from the first HARQ-ACK resource.
The method of claim 26, comprising determining the first and second HARQ-ACK resources based on higher layer signaling.
The method of claim 23, wherein determining the first HARQ-ACK resource corresponding to the second set of subframes comprises determining the first HARQ-ACK resource based on a predetermined mapping between the first HARQ-ACK resource and a cardinality of the second set of subframes.
The method of claim 28, wherein the predetermined mapping between the first HARQ-ACK resource and the cardinality of the second set of subframes is fixed or configured by higher layer signaling.
The method of claim 28, wherein the predetermined mapping establishes a correspondence between a second HARQ-ACK resource and a cardinality of the first set of subframes and wherein the second HARQ-ACK resource is different from the first HARQ-ACK resource.