HARQ-ACK WITH TIME-DOMAIN BUNDLING FOR PDSCHS SCHEDULED BY MULTI-TTI DCI PRIORITY CLAIMS [0001] This application claims priority to International Application No. PCT/CN2021/070771 filed January 8, 2021 [reference number AD4512-PCT-Z] and to International Application No. PCT/CN2021/103934 filed July 1, 2021 [reference number AD7593-PCT-Z], which are incorporated herein by reference in their entireties. [0002] This application also claims priority to United States Provisional Patent Application Serial No.63/246,267 filed September 20, 2021 [reference number AD8935-Z] which is incorporated herein by reference in its entirety. TECHNICAL FIELD [0003] Embodiments pertain to wireless communications. Some embodiments relate to wireless networks including 3GPP (Third Generation Partnership Project) and fifth-generation (5G) networks including 5G new radio (NR) (or 5G-NR) networks. Some embodiments relate to sixth-generation (6G) networks. Some embodiments relate to Hybrid Automatic Repeat Request acknowledgement (HARQ-ACK) and HARQ-ACK codebook generation. BACKGROUND [0004] Mobile communications have evolved significantly from early voice systems to today’s highly sophisticated integrated communication platform. With the increase in different types of devices communicating with various network devices, usage of 3GPP 5G NR systems has increased. The penetration of mobile devices (user equipment or UEs) in modern society has continued to drive demand for a wide variety of networked devices in many disparate environments.5G NR wireless systems are forthcoming and are expected to enable even greater speed, connectivity, and usability, and are expected to increase throughput, coverage, and robustness and reduce latency and operational and capital expenditures.5G-NR networks will continue to evolve based on 3GPP LTE-Advanced with additional potential new radio access technologies (RATs) to enrich people’s lives with seamless wireless connectivity solutions delivering fast, rich content and services. As current cellular network frequency is saturated, higher frequencies, such as millimeter wave (mmWave) frequency, can be beneficial due to their high bandwidth. [0005] One issue with systems operating above a 52.6 GHz carrier frequency is that slot durations are shorter, particularly for larger subcarrier spacings (SCS). Therefore, it may be beneficial to reduce the HARQ-ACK payload on the uplink channels. BRIEF DESCRIPTION OF THE DRAWINGS [0006] FIG.1A illustrates an architecture of a network, in accordance with some embodiments. [0007] FIG.1B and FIG.1C illustrate a non-roaming 5G system architecture in accordance with some embodiments. [0008] FIG.2A illustrates an example of short slot duration of larger subcarrier spacing, in accordance with various embodiments. [0009] FIG.2B illustrates one example of multi-transmission time interval (TTI) scheduling for physical downlink shared channels (PDSCHs), in accordance with various embodiments. [0010] FIG.3 illustrates an example of time bundling of PDSCHs scheduled by a multi-TTI downlink control information (DCI), in accordance with various embodiments. [0011] FIG.4 illustrates another example of time bundling of PDSCHs scheduled by a multi-TTI DCI, in accordance with various embodiments. [0012] FIG.5 illustrates an example of time bundling and spatial bundling of PDSCHs scheduled by a multi-TTI DCI, in accordance with various embodiments. [0013] FIG.6 illustrates another example of time bundling and spatial bundling of PDSCHs scheduled by a multi-TTI DCI, in accordance with various embodiments. [0014] FIG.7 illustrates an example of code block group (CBG) bundling for a PDSCH scheduled by a multi-TTI DCI, in accordance with various embodiments. [0015] FIG.8 illustrates an example of CBG bundling across multiple PDSCHs scheduled by a multi-TTI DCI, in accordance with various embodiments. [0016] FIG.9 illustrates another example of CBG bundling for a PDSCH scheduled by a multi-TTI DCI, in accordance with various embodiments. [0017] FIG.10 illustrates another example of CBG bundling across multiple PDSCHs scheduled by a multi-TTI DCI, in accordance with various embodiments. [0018] FIG.11 illustrates an example of transport block (TB) or CBG based hybrid automatic repeat request (HARQ)-acknowledgement (ACK) feedback, in accordance with various embodiments. [0019] FIG.12 illustrates an example of the same start and length indicator value (SLIV) in multiple slots for multi-TTI scheduling, in accordance with various embodiments. [0020] FIG.13 illustrates an example of multiple SLIVs in multiple slots for multi-TTI scheduling, in accordance with various embodiments. [0021] FIG.14 illustrates an example of HARQ-ACK codebook design, including a time domain resource of multi-TTI scheduling limited by set of K1, in accordance with various embodiments. [0022] FIG.15 is a function block diagram of a wireless communication device in accordance with some embodiments. [0023] FIG.16 is a procedure for time-domain bundling HARQ-ACK information in accordance with some embodiments. DETAILED DESCRIPTION [0024] The following description and the drawings sufficiently illustrate specific embodiments to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Portions and features of some embodiments may be included in, or substituted for, those of other embodiments. Embodiments set forth in the claims encompass all available equivalents of those claims. [0025] Some embodiments are directed to a user equipment (UE) configured for time-domain bundling of HARQ-ACK information for two or more PDSCHs scheduled by a multi-TTI DCI. The UE may decode a PDCCH carrying a multi-TTI DCI that may schedule two or more PDSCHs, each comprising at least one transport block (TB). The UE may generate a HARQ- ACK codebook for the two or more PDSCHs scheduled by the multi-TTI DCI by applying time-domain bundling to the HARQ-ACK information for the two or more PDSCHs such that the HARQ-ACK information for two or more of the PDSCHs is bundled into one bit. The UE may encode the HARQ-ACK codebook for the two or more PDSCHs for transmission on an uplink channel to a gNB. These embodiments as well as others are described in more detail below. [0026] As defined in NR, one slot has 14 symbols. For system operating above 52.6GHz carrier frequency, if larger subcarrier spacing, e.g., 1.92MHz or 3.84MHz is employed, the slot duration can be very short. For instance, for 1.92MHz subcarrier spacing, one slot duration is approximately 7.8µs as shown in FIG.2A. This extremely short slot duration may not be sufficient for higher layer processing, including Medium Access Layer (MAC) and Radio Link Control (RLC), etc. In this case, certain mechanisms may need to be defined to allow long transmission duration and adequate processing time for higher layer or even scheduler implementation. [0027] Various embodiments disclosed herein provide techniques for HARQ-ACK transmission when multi-Transmission Time Interval (TTI) scheduling for data transmission is used in a system operating above 52.6GHz carrier frequency. [0028] FIG.1A illustrates an architecture of a network in accordance with some embodiments. The network 140A is shown to include user equipment (UE) 101 and UE 102. The UEs 101 and 102 are illustrated as smartphones (e.g., handheld touchscreen mobile computing devices connectable to one or more cellular networks) but may also include any mobile or non-mobile computing device, such as Personal Data Assistants (PDAs), pagers, laptop computers, desktop computers, wireless handsets, drones, or any other computing device including a wired and/or wireless communications interface. The UEs 101 and 102 can be collectively referred to herein as UE 101, and UE 101 can be used to perform one or more of the techniques disclosed herein. [0029] Any of the radio links described herein (e.g., as used in the network 140A or any other illustrated network) may operate according to any exemplary radio communication technology and/or standard. [0030] LTE and LTE-Advanced are standards for wireless communications of high-speed data for UE such as mobile telephones. In LTE- Advanced and various wireless systems, carrier aggregation is a technology according to which multiple carrier signals operating on different frequencies may be used to carry communications for a single UE, thus increasing the bandwidth available to a single device. In some embodiments, carrier aggregation may be used where one or more component carriers operate on unlicensed frequencies. [0031] Embodiments described herein can be used in the context of any spectrum management scheme including, for example, dedicated licensed spectrum, unlicensed spectrum, (licensed) shared spectrum (such as Licensed Shared Access (LSA) in 2.3-2.4 GHz, 3.4-3.6 GHz, 3.6-3.8 GHz, and further frequencies and Spectrum Access System (SAS) in 3.55-3.7 GHz and further frequencies). [0032] Embodiments described herein can also be applied to different Single Carrier or OFDM flavors (CP-OFDM, SC-FDMA, SC-OFDM, filter bank-based multicarrier (FBMC), OFDMA, etc.) and in particular 3GPP NR (New Radio) by allocating the OFDM carrier data bit vectors to the corresponding symbol resources. [0033] In some embodiments, any of the UEs 101 and 102 can comprise an Internet-of-Things (IoT) UE or a Cellular IoT (CIoT) UE, which can comprise a network access layer designed for low-power IoT applications utilizing short-lived UE connections. In some embodiments, any of the UEs 101 and 102 can include a narrowband (NB) IoT UE (e.g., such as an enhanced NB- IoT (eNB-IoT) UE and Further Enhanced (FeNB-IoT) UE). An IoT UE can utilize technologies such as machine-to-machine (M2M) or machine-type communications (MTC) for exchanging data with an MTC server or device via a public land mobile network (PLMN), Proximity-Based Service (ProSe) or device-to-device (D2D) communication, sensor networks, or IoT networks. The M2M or MTC exchange of data may be a machine-initiated exchange of data. An IoT network includes interconnecting IoT UEs, which may include uniquely identifiable embedded computing devices (within the Internet infrastructure), with short-lived connections. The IoT UEs may execute background applications (e.g., keep-alive messages, status updates, etc.) to facilitate the connections of the IoT network. [0034] In some embodiments, any of the UEs 101 and 102 can include enhanced MTC (eMTC) UEs or further enhanced MTC (FeMTC) UEs. [0035] The UEs 101 and 102 may be configured to connect, e.g., communicatively couple, with a radio access network (RAN) 110. The RAN 110 may be, for example, an Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN), a NextGen RAN (NG RAN), or some other type of RAN. The UEs 101 and 102 utilize connections 103 and 104, respectively, each of which comprises a physical communications interface or layer (discussed in further detail below); in this example, the connections 103 and 104 are illustrated as an air interface to enable communicative coupling and can be consistent with cellular communications protocols, such as a Global System for Mobile Communications (GSM) protocol, a code-division multiple access (CDMA) network protocol, a Push-to- Talk (PTT) protocol, a PTT over Cellular (POC) protocol, a Universal Mobile Telecommunications System (UMTS) protocol, a 3GPP Long Term Evolution (LTE) protocol, a fifth-generation (5G) protocol, a New Radio (NR) protocol, and the like. [0036] In an aspect, the UEs 101 and 102 may further directly exchange communication data via a ProSe interface 105. The ProSe interface 105 may alternatively be referred to as a sidelink interface comprising one or more logical channels, including but not limited to a Physical Sidelink Control Channel (PSCCH), a Physical Sidelink Shared Channel (PSSCH), a Physical Sidelink Discovery Channel (PSDCH), and a Physical Sidelink Broadcast Channel (PSBCH). [0037] The UE 102 is shown to be configured to access an access point (AP) 106 via connection 107. The connection 107 can comprise a local wireless connection, such as, for example, a connection consistent with any IEEE 802.11 protocol, according to which the AP 106 can comprise a wireless fidelity (WiFi) router. In this example, the AP 106 is shown to be connected to the Internet without connecting to the core network of the wireless system (described in further detail below). [0038] The RAN 110 can include one or more access nodes that enable the connections 103 and 104. These access nodes (ANs) can be referred to as base stations (BSs), NodeBs, evolved NodeBs (eNBs), Next Generation NodeBs (gNBs), RAN nodes, and the like, and can comprise ground stations (e.g., terrestrial access points) or satellite stations providing coverage within a geographic area (e.g., a cell). In some embodiments, the communication nodes 111 and 112 can be transmission/reception points (TRPs). In instances when the communication nodes 111 and 112 are NodeBs (e.g., eNBs or gNBs), one or more TRPs can function within the communication cell of the NodeBs. The RAN 110 may include one or more RAN nodes for providing macrocells, e.g., macro-RAN node 111, and one or more RAN nodes for providing femtocells or picocells (e.g., cells having smaller coverage areas, smaller user capacity, or higher bandwidth compared to macrocells), e.g., low power (LP) RAN node 112. [0039] Any of the RAN nodes 111 and 112 can terminate the air interface protocol and can be the first point of contact for the UEs 101 and 102. In some embodiments, any of the RAN nodes 111 and 112 can fulfill various logical functions for the RAN 110 including, but not limited to, radio network controller (RNC) functions such as radio bearer management, uplink and downlink dynamic radio resource management and data packet scheduling, and mobility management. In an example, any of the nodes 111 and/or 112 can be a new generation Node-B (gNB), an evolved node-B (eNB), or another type of RAN node. [0040] The RAN 110 is shown to be communicatively coupled to a core network (CN) 120 via an S1 interface 113. In embodiments, the CN 120 may be an evolved packet core (EPC) network, a NextGen Packet Core (NPC) network, or some other type of CN (e.g., as illustrated in reference to FIGS.1B-1C). In this aspect, the S1 interface 113 is split into two parts: the S1-U interface 114, which carries traffic data between the RAN nodes 111 and 112 and the serving gateway (S-GW) 122, and the S1-mobility management entity (MME) interface 115, which is a signaling interface between the RAN nodes 111 and 112 and MMEs 121. [0041] In this aspect, the CN 120 comprises the MMEs 121, the S-GW 122, the Packet Data Network (PDN) Gateway (P-GW) 123, and a home subscriber server (HSS) 124. The MMEs 121 may be similar in function to the control plane of legacy Serving General Packet Radio Service (GPRS) Support Nodes (SGSN). The MMEs 121 may manage mobility embodiments in access such as gateway selection and tracking area list management. The HSS 124 may comprise a database for network users, including subscription-related information to support the network entities' handling of communication sessions. The CN 120 may comprise one or several HSSs 124, depending on the number of mobile subscribers, on the capacity of the equipment, on the organization of the network, etc. For example, the HSS 124 can provide support for routing/roaming, authentication, authorization, naming/addressing resolution, location dependencies, etc. [0042] The S-GW 122 may terminate the S1 interface 113 towards the RAN 110, and routes data packets between the RAN 110 and the CN 120. In addition, the S-GW 122 may be a local mobility anchor point for inter-RAN node handovers and also may provide an anchor for inter-3GPP mobility. Other responsibilities of the S-GW 122 may include a lawful intercept, charging, and some policy enforcement. [0043] The P-GW 123 may terminate an SGi interface toward a PDN. The P-GW 123 may route data packets between the EPC network 120 and external networks such as a network including the application server 184 (alternatively referred to as application function (AF)) via an Internet Protocol (IP) interface 125. The P-GW 123 can also communicate data to other external networks 131A, which can include the Internet, IP multimedia subsystem (IPS) network, and other networks. Generally, the application server 184 may be an element offering applications that use IP bearer resources with the core network (e.g., UMTS Packet Services (PS) domain, LTE PS data services, etc.). In this aspect, the P-GW 123 is shown to be communicatively coupled to an application server 184 via an IP interface 125. The application server 184 can also be configured to support one or more communication services (e.g., Voice-over- Internet Protocol (VoIP) sessions, PTT sessions, group communication sessions, social networking services, etc.) for the UEs 101 and 102 via the CN 120. [0044] The P-GW 123 may further be a node for policy enforcement and charging data collection. Policy and Charging Rules Function (PCRF) 126 is the policy and charging control element of the CN 120. In a non-roaming scenario, in some embodiments, there may be a single PCRF in the Home Public Land Mobile Network (HPLMN) associated with a UE's Internet Protocol Connectivity Access Network (IP-CAN) session. In a roaming scenario with a local breakout of traffic, there may be two PCRFs associated with a UE's IP- CAN session: a Home PCRF (H-PCRF) within an HPLMN and a Visited PCRF (V-PCRF) within a Visited Public Land Mobile Network (VPLMN). The PCRF 126 may be communicatively coupled to the application server 184 via the P- GW 123. [0045] In some embodiments, the communication network 140A can be an IoT network or a 5G network, including 5G new radio network using communications in the licensed (5G NR) and the unlicensed (5G NR-U) spectrum. One of the current enablers of IoT is the narrowband-IoT (NB-IoT). [0046] An NG system architecture can include the RAN 110 and a 5G network core (5GC) 120. The NG-RAN 110 can include a plurality of nodes, such as gNBs and NG-eNBs. The core network 120 (e.g., a 5G core network or 5GC) can include an access and mobility function (AMF) and/or a user plane function (UPF). The AMF and the UPF can be communicatively coupled to the gNBs and the NG-eNBs via NG interfaces. More specifically, in some embodiments, the gNBs and the NG-eNBs can be connected to the AMF by NG- C interfaces, and to the UPF by NG-U interfaces. The gNBs and the NG-eNBs can be coupled to each other via Xn interfaces. [0047] In some embodiments, the NG system architecture can use reference points between various nodes as provided by 3GPP Technical Specification (TS) 23.501 (e.g., V15.4.0, 2018-12). In some embodiments, each of the gNBs and the NG-eNBs can be implemented as a base station, a mobile edge server, a small cell, a home eNB, and so forth. In some embodiments, a gNB can be a master node (MN) and NG-eNB can be a secondary node (SN) in a 5G architecture. [0048] FIG.1B illustrates a non-roaming 5G system architecture in accordance with some embodiments. Referring to FIG.1B, there is illustrated a 5G system architecture 140B in a reference point representation. More specifically, UE 102 can be in communication with RAN 110 as well as one or more other 5G core (5GC) network entities. The 5G system architecture 140B includes a plurality of network functions (NFs), such as access and mobility management function (AMF) 132, session management function (SMF) 136, policy control function (PCF) 148, application function (AF) 150, user plane function (UPF) 134, network slice selection function (NSSF) 142, authentication server function (AUSF) 144, and unified data management (UDM)/home subscriber server (HSS) 146. The UPF 134 can provide a connection to a data network (DN) 152, which can include, for example, operator services, Internet access, or third-party services. The AMF 132 can be used to manage access control and mobility and can also include network slice selection functionality. The SMF 136 can be configured to set up and manage various sessions according to network policy. The UPF 134 can be deployed in one or more configurations according to the desired service type. The PCF 148 can be configured to provide a policy framework using network slicing, mobility management, and roaming (similar to PCRF in a 4G communication system). The UDM can be configured to store subscriber profiles and data (similar to an HSS in a 4G communication system). [0049] In some embodiments, the 5G system architecture 140B includes an IP multimedia subsystem (IMS) 168B as well as a plurality of IP multimedia core network subsystem entities, such as call session control functions (CSCFs). More specifically, the IMS 168B includes a CSCF, which can act as a proxy CSCF (P-CSCF) 162BE, a serving CSCF (S-CSCF) 164B, an emergency CSCF (E-CSCF) (not illustrated in FIG.1B), or interrogating CSCF (I-CSCF) 166B. The P-CSCF 162B can be configured to be the first contact point for the UE 102 within the IM subsystem (IMS) 168B. The S-CSCF 164B can be configured to handle the session states in the network, and the E-CSCF can be configured to handle certain embodiments of emergency sessions such as routing an emergency request to the correct emergency center or PSAP. The I-CSCF 166B can be configured to function as the contact point within an operator's network for all IMS connections destined to a subscriber of that network operator, or a roaming subscriber currently located within that network operator's service area. In some embodiments, the I-CSCF 166B can be connected to another IP multimedia network 170E, e.g. an IMS operated by a different network operator. [0050] In some embodiments, the UDM/HSS 146 can be coupled to an application server 160E, which can include a telephony application server (TAS) or another application server (AS). The AS 160B can be coupled to the IMS 168B via the S-CSCF 164B or the I-CSCF 166B. [0051] A reference point representation shows that interaction can exist between corresponding NF services. For example, FIG.1B illustrates the following reference points: N1 (between the UE 102 and the AMF 132), N2 (between the RAN 110 and the AMF 132), N3 (between the RAN 110 and the UPF 134), N4 (between the SMF 136 and the UPF 134), N5 (between the PCF 148 and the AF 150, not shown), N6 (between the UPF 134 and the DN 152), N7 (between the SMF 136 and the PCF 148, not shown), N8 (between the UDM 146 and the AMF 132, not shown), N9 (between two UPFs 134, not shown), N10 (between the UDM 146 and the SMF 136, not shown), N11 (between the AMF 132 and the SMF 136, not shown), N12 (between the AUSF 144 and the AMF 132, not shown), N13 (between the AUSF 144 and the UDM 146, not shown), N14 (between two AMFs 132, not shown), N15 (between the PCF 148 and the AMF 132 in case of a non-roaming scenario, or between the PCF 148 and a visited network and AMF 132 in case of a roaming scenario, not shown), N16 (between two SMFs, not shown), and N22 (between AMF 132 and NSSF 142, not shown). Other reference point representations not shown in FIG.1B can also be used. [0052] FIG.1C illustrates a 5G system architecture 140C and a service- based representation. In addition to the network entities illustrated in FIG.1B, system architecture 140C can also include a network exposure function (NEF) 154 and a network repository function (NRF) 156. In some embodiments, 5G system architectures can be service-based and interaction between network functions can be represented by corresponding point-to-point reference points Ni or as service-based interfaces. [0053] In some embodiments, as illustrated in FIG.1C, service-based representations can be used to represent network functions within the control plane that enable other authorized network functions to access their services. In this regard, 5G system architecture 140C can include the following service-based interfaces: Namf 158H (a service-based interface exhibited by the AMF 132), Nsmf 158I (a service-based interface exhibited by the SMF 136), Nnef 158B (a service-based interface exhibited by the NEF 154), Npcf 158D (a service-based interface exhibited by the PCF 148), a Nudm 158E (a service-based interface exhibited by the UDM 146), Naf 158F (a service-based interface exhibited by the AF 150), Nnrf 158C (a service-based interface exhibited by the NRF 156), Nnssf 158A (a service-based interface exhibited by the NSSF 142), Nausf 158G (a service-based interface exhibited by the AUSF 144). Other service-based interfaces (e.g., Nudr, N5g-eir, and Nudsf) not shown in FIG.1C can also be used. [0054] In some embodiments, any of the UEs or base stations described in connection with FIGS.1A-1C can be configured to perform the functionalities described herein. [0055] Mobile communication has evolved significantly from early voice systems to today’s highly sophisticated integrated communication platform. The next generation wireless communication system, 5G, or new radio (NR) will provide access to information and sharing of data anywhere, anytime by various users and applications. NR is expected to be a unified network/system that targets to meet vastly different and sometimes conflicting performance dimensions and services. Such diverse multi-dimensional requirements are driven by different services and applications. In general, NR will evolve based on 3GPP LTE-Advanced with additional potential new Radio Access Technologies (RATs) to enrich people's lives with better, simple, and seamless wireless connectivity solutions. NR will enable everything connected by wireless and deliver fast, rich content and services. [0056] Rel-15 NR systems are designed to operate on the licensed spectrum. The NR-unlicensed (NR-U), a short-hand notation of the NR-based access to unlicensed spectrum, is a technology that enables the operation of NR systems on the unlicensed spectrum. [0057] As mentioned above, for NR one slot has 14 symbols. For system operating above 52.6GHz carrier frequency, if larger subcarrier spacing, e.g., 1.92MHz or 3.84MHz is employed, the slot duration can be very short. For instance, for 1.92MHz subcarrier spacing, one slot duration is approximately 7.8µs as shown in FIG.2A. This extremely short slot duration may not be sufficient for higher layer processing, including Medium Access Layer (MAC) and Radio Link Control (RLC), etc. In this case, certain mechanisms may need to be defined to allow long transmission duration and adequate processing time for higher layer or even a scheduler implementation. [0058] For practical implementation of a scheduler, a long scheduling unit may be considered for the transmission of data channel. A physical downlink control channel (PDCCH) carrying downlink control information (DCI) may be used to schedule one or more physical downlink shared channel (PDSCH) with different transport block (TBs) in different slots. Such a DCI is referred as a multi-TTI DCI. Note: The number of scheduled PDSCHs by the DCI may be explicitly indicated by a field in the DCI. Alternatively, the number of scheduled PDSCHs by the DCI is jointly coded with other information field(s). For example, the number of scheduled PDSCHs for a row in a time domain resource allocation (TDRA) table equals to the number of configured SLIVs of the row. The maximum number of PDSCHs scheduled by a multi-TTI DCI is the maximum number of scheduled PDSCHs of all rows. [0059] FIG.2B illustrates one example of multi-TTI scheduling for PDSCHs. In this example, 4 PDSCHs (PDSCH#0-3) with different transport blocks (TB) are scheduled by a single DCI. [0060] Time domain bundling for HARQ-ACK transmission [0061] The use of multi-TTI scheduling for PDSCH transmission does not necessarily mean that the uplink channel condition is good. Therefore, it is beneficial to apply certain bundling scheme to reduce HARQ-ACK payload on PUCCH or PUSCH. Since the multiple PDSCHs are scheduled by the same DCI, they are either received or not received as a whole. Consequently, there will be no error case of missing a subset of the multiple PDSCHs. Therefore, bundling of HARQ-ACK bits for PDSCHs scheduled by a multi-TTI DCI is error free. [0062] In one embodiment, time domain bundling for the HARQ-ACK of the multiple PDSCHs scheduled by a multi-TTI DCI can be used. [0063] In one option, time domain bundling could be applied to all PDSCHs scheduled by a multi-TTI DCI. FIG.3 illustrates one example of this option. The four PDSCHs are scheduled by a multi-TTI DCI. HARQ-ACK for the 4 PDSCHs are bundled into one bit. If each PDSCH is scheduled with two TBs on the two spatial codeword (CW)s, time domain bunding could apply to the TBs of each codeword respectively. [0064] In another option, time domain bundling could be applied to each subset of PDSCHs scheduled by a multi-TTI DCI. A subset of PDSCHs may include consecutive or non-consecutive PDSCHs scheduled by the multi-TTI DCI. FIG.4 illustrates one example of this option. The 4 PDSCHs are scheduled by a multi-TTI DCI. HARQ-ACK for every 2 PDSCHs are bundled into one bit so that 2 bundled HARQ-ACK bits are generated. If each PDSCH is scheduled with two TBs on the two spatial codeword (CW)s, HARQ-ACK of the same codeword of two PDSCHs are bundled to get one bit, which generates 4 bundled HARQ-ACK bits. [0065] In one embodiment, time domain bundling could be used together with spatial bundling to compress the HARQ-ACK payload for the multiple PDSCHs scheduled by a multi-TTI DCI. [0066] In one option, time domain bundling and spatial bundling could be applied to all PDSCHs scheduled by a multi-TTI DCI to get one HARQ-ACK bit. FIG.5 illustrates one example of this option. [0067] In one option, time domain bundling and spatial bundling could be applied to each subset of the PDSCHs scheduled by a multi-TTI DCI. A subset of PDSCHs may include consecutive or non-consecutive PDSCHs scheduled by the multi-TTI DCI. FIG.6 illustrates one example of this option. HARQ-ACK for the two codewords of two PDSCHs are bundled to one bit. This option provides an alternative way to compress to 2 HARQ-ACK bits instead of the option in FIG.3. [0068] CBG bundling for HARQ-ACK transmission [0069] Bundling of HARQ-ACKs of CBGs, e.g. CBG bundling can be done to reduce HARQ-ACK payload. If a PDSCH that is scheduled by a multi- TTI DCI can have two TBs or codewords, CBG bundling can be done per codeword. Alternatively, spatial bundling of HARQ-ACKs for the CBGs with same index of the two TBs of a PDSCH can be done first. Then CBG bundling of spatial bundled HARQ-ACK bits can be further performed. The HARQ-ACK for a CBG that is not transmitted in a PDSCH is neglected or is considered as an ACK. In the following, we describe CBG bundling assuming single codeword. The same schemes can be extended for the case that each PDSCH has two codewords. [0070] In one embodiment, CBG bundling for the HARQ-ACK could be applied to the one or multiple PDSCHs scheduled by a multi-TTI DCI, according to the maximum number of PDSCHs scheduled by a multi-TTI DCI. The number of configured CBGs for a PDSCH may be used in CBG bundling. By this way, the pattern for CBG bundling is fixed. Alternatively, the actual number of scheduled CBGs for each PDSCH may be used in CBG bundling. In the following descriptions, the maximum number of PDSCHs scheduled by a multi-TTI DCI is P, the number of configured CBGs for a PDSCH is M, the actual number of scheduled CBGs for a PDSCH is , , the number of bundled HARQ-ACK bits associated with a multi-TTI DCI is N. [0071] In one option, CBG bundling could be applied to the HARQ- ACK of each subset of CBGs of a PDSCH that is scheduled by a multi-TTI DCI. A subset of CBGs may include consecutive or non-consecutive CBGs of the PDSCH. The number of bundled HARQ-ACK bits associated with a PDSCH can be or . CBG bundling could be applied to the HARQ-ACK of each subset of configured CBGs of the PDSCH. The number of CBGs of the PDSCH that are bundled to get one HARQ-ACK bit can be determined by the number of configured CBGs of the PDSCH, e.g. or . Alternatively, CBG bundling could be applied to the HARQ-ACK of each subset of scheduled CBGs of the PDSCH. The number of CBGs of the PDSCH that are bundled to get one HARQ-ACK bit can be determined by the actual number of scheduled CBGs of the PDSCH, In an extreme case, if equals to 1 for a PDSCH, the option is equivalent to generate TB based HARQ-ACK feedback. [0072] FIG.7 illustrates one example of this option. The two PDSCHs are scheduled by a multi-TTI DCI and each PDSCH has 4 configured CBGs. HARQ-ACK for 2 CBGs of a PDSCH are bundled into one bit, which generates 4 bundled HARQ-ACK bits. [0073] In another option, CBG bundling could be applied to the HARQ- ACK of configured CBGs of one or multiple PDSCHs that are scheduled by a multi-TTI DCI. The number of CBGs that are bundled to get one HARQ-ACK bit can . set of CBGs for which the HARQ-ACKs are bundled can be consecutive or non-consecutive CBGs. The set of CBGs may include the CBGs with same index of two or more PDSCHs. [0074] FIG.8 illustrates one example of this option. The two PDSCHs are scheduled by a multi-TTI DCI and each PDSCH has 4 configured CBGs. To generate 3 bundled HARQ-ACK bits, HARQ-ACKs of 3 CBGs of PDSCH 1 are bundled to one bit, HARQ-ACKs of the last CBG of PDSCH 1 and 2 CBGs of PDSCH 2 are bundled to one bit, and HARQ-ACKs of the last 2 CBGs of PDSCH 2 are bundled to one bit. [0075] In one embodiment, CBG bundling for the HARQ-ACK could be applied to the one or multiple PDSCHs scheduled by a multi-TTI DCI, according to the actual number of scheduled PDSCHs scheduled by the multi- TTI DCI. By this way, the pattern for CBG bundling is dependent on the actual number of scheduled PDSCHs. The number of configured CBGs for a PDSCH may be used in CBG bundling. Alternatively, the actual number of scheduled CBGs for each PDSCH may be used in CBG bundling. In the following descriptions, the actual number of PDSCHs scheduled by a multi-TTI DCI is P, the number of configured CBGs for a PDSCH is M, the actual number of scheduled CBGs for a PDSCH is , , the number of bundled HARQ-ACK bits associated with a multi-TTI DCI is N. [0076] In one option, CBG bundling could be applied to the HARQ- ACK of each subset of CBGs of a PDSCH that is scheduled by a multi-TTI DCI. A subset of CBGs may include consecutive or non-consecutive CBGs of the PDSCH. The number of bundled HARQ-ACK bits associated with a PDSCH can be . CBG bundling could be applied to the HARQ-ACK of each subset of configured CBGs of the PDSCH. The number of CBGs of the PDSCH that are bundled to get one HARQ-ACK bit can be determined by the number of configured CBGs of the PDSCH, e.g. or . Alternatively, CBG bundling could be applied to the HARQ-ACK of each subset of scheduled CBGs of the PDSCH. The number of CBGs of the PDSCH that are bundled to get one HARQ-ACK bit is determined by the actual number of scheduled CBGs of the PDSCH, e.g. o . In an extreme case, if equals to 1, the option is equivalent to generate TB based HARQ-ACK feedback. [0077] FIG.9 illustrates one example of this option. The two PDSCHs are scheduled by a multi-TTI DCI. Each PDSCH has 4 configured CBGs. However, only 3 CBGs are scheduled for each PDSCH by the multi-TTI DCI. For each PDSCH, HARQ-ACK for 2 CBGs are bundled into one bit and HARQ- ACK for the other CBG is directly reported without bundling. The total number of bits after CBG bundling is 4. [0078] In another option, CBG bundling could be applied to the HARQ- ACK of scheduled CBGs of one or multiple PDSCHs that are scheduled by a multi-TTI DCI. The number of CBGs that are bundled to get one HARQ-ACK bit is If the PDSCHs scheduled by a multi-TTI DCI have same number of CBGs, e.g. A set of CBGs for which the HARQ-ACKs are bundled can be consecutive or non-consecutive CBGs. The set of CBGs may include the CBGs with same index of two or more PDSCHs. [0079] FIG.10 illustrates one example of this option. The two PDSCHs are scheduled by a multi-TTI DCI. Each PDSCH has 4 configured CBGs. However, only 3 CBGs are scheduled for each PDSCH by the multi-TTI DCI. To generate 3 bundled HARQ-ACK bits, HARQ-ACKs of 2 CBGs of PDSCH 1 are bundled to one bit, HARQ-ACKs of the last CBG of PDSCH 1 and one CBG of PDSCH 2 are bundled to one bit, and HARQ-ACKs of the last 2 CBGs of PDSCH 2 are bundled to one bit. [0080] TB or CBG based HARQ-ACK feedback [0081] CBG based transmission is a means to improve DL spectral efficiency. HARQ-ACK for the one or multiple PDSCHs scheduled by a multi- TTI DCI needs to be designed considering the support of CBG based transmission. [0082] In one embodiment, if CBG based transmission is configured, when only one TTI is scheduled by a multi-TTI DCI, CBG based HARQ-ACK feedback is reported for the TTI. On the other hand, when more than one TTIs are scheduled by the multi-TTI DCI, TB-based HARQ-ACK feedback applies. [0083] In one option, the number of HARQ-ACK bits when single TTI or multiple TTIs are scheduled by the multi-TTI DCI can be separately determined. The number of HARQ-ACK bits if single TTI is scheduled by a multi-TTI DCI could be the maximum number of CBGs that is configured by high layer signaling, the actual number of CBGs of the single TTI, or indicated by the DCI. The above high layer signaling could be same as or different from the configuration of the maximum number of CBGs that can be scheduled by a single-TTI DCI. A single-TTI DCI can only schedule PDSCH in one TTI. On the other hand, the number of HARQ-ACK bits if multiple TTIs are scheduled by a multi-TTI DCI could equal to the maximum number of TTIs or TBs configured by high layer signaling, or the actual number of TTIs or TBs in the scheduled TTIs or indicated by the multi-TTI DCI. [0084] In another option, the number of HARQ-ACK bits N, when single TTI or multiple TTIs are scheduled by the multi-TTI DCI, are the same. N could be the configured by a high layer signaling. Alternatively, N could be ^{determined as the maximum of:} _{x The maximum number of CBGs configured by high layer that can} b ^{e scheduled by a single-TTI DCI.} _{x The maximum number of CBGs configured by high layer that can} b ^{e scheduled by a multi-TTI DCI which schedules a single TTI.} _{x Maximum number of TBs scheduled by a multi-TTI DCI. Each} T ^{TI scheduled by the multi-TTI DCI consists one or two TBs.} _{x The number of HARQ-ACK bits that is associated with a multi-} TTI DCI is separately determined for each serving cell; or is the maximum number of HARQ-ACK bits that is associated with a multi- TTI DCI of all serving cells. [0085] In one embodiment, denote the number of HARQ-ACK bits associated with a multi-TTI DCI as N, CBG based HARQ-ACK feedback may be applied when one or more TTIs are scheduled by a multi-TTI DCI, which may use the N bits efficiently. N could be the configured by a high layer ^{signaling. Alternatively, N could be determined as the maximum of:} _{x The maximum number of CBGs configured by high layer that can} b ^{e scheduled by a single-TTI DCI.} _{x The maximum number of CBGs configured by high layer that can} b ^{e scheduled by a multi-TTI DCI which schedules a single TTI.} _{x Maximum number of TBs scheduled by a multi-TTI DCI. Each} T ^{TI scheduled by the multi-TTI DCI consists one or two TBs.} _{x Total number of HARQ-ACK bits of the one or multiple TTIs} s ^{cheduled by a multi-TTI DCI, if configured.} _{x The number of HARQ-ACK bits that is associated with a multi-} TTI DCI is separately determined for each serving cell; or is the maximum number of HARQ-ACK bits that is associated with a multi- TTI DCI of all serving cells. [0086] A multi-TTI DCI may include a CBG transmission information (CBGTI) field only when single TTI is scheduled. Alternatively, A multi-TTI DCI may include a CBGTI field for Z TTIs scheduled by the DCI. Z can be configured by high layer signaling or derived by other information. [0087] In one option, if X is the largest value so that the total number of configured CBGs of X TTIs scheduled by a multi-TTI DCI for a serving cell is ^{no more than N,} _{x If the number of TTI(s) scheduled by the multi-TTI DCI is no} m ^{ore than X, CBG based HARQ-ACK bits are reported for the TTI(s);} _{x Otherwise, TB based HARQ-ACK bits are reported for the} TTI(s). [0088] FIG.11 illustrates one example of this option. It is assumed that up to 4 TTIs could be scheduled by a multi-TTI DCI, the number of CBGs per TTI is 4, and 8 HARQ-ACK bits could be reported for the TTI(s) scheduled by a multi-TTI DCI. As shown in the upper portion of FIG.11, when two TTIs are scheduled by the multi-TTI DCI, CBG based HARQ-ACK feedback applies for the two TTIs to get 8 HARQ-ACK bits. On the other hand, as shown in the lower portion of FIG.11 , when 4 TTIs scheduled by the multi-TTI DCI, 4 TB- based HARQ-ACK bits for the 4 TTIs are reported. [0089] In another option, if the total number of scheduled CBGs in the TTI(s) scheduled by a multi-TTI DCI for a serving cell is no more than N, CBG based HARQ-ACK bits are reported for the TTI(s); otherwise, TB based HARQ- ACK bits are reported for the TTI(s). [0090] In another option, if the total number of configured CBGs of the TTI(s) scheduled by a multi-TTI DCI for a serving cell is larger than N, TB based HARQ-ACK feedback applies to Y TTI(s) that are scheduled by the multi- TTI DCI, e.g. the last Y TTI(s), while CBG based HARQ-ACK feedback still applies to other TTI(s). Y is the smallest value so that the total number of HARQ-ACK bits for the TTI(s) scheduled by the multi-TTI doesn’t exceed N. [0091] In another option, if the total number of scheduled CBGs of the TTI(s) scheduled by a multi-TTI DCI for a serving cell is larger than N, TB based HARQ-ACK feedback applies to Y TTI(s) that are scheduled by the multi- TTI DCI, e.g. the last Y TTI(s), while CBG based HARQ-ACK feedback still applies to other TTI(s). Y is the smallest value so that the total number of HARQ-ACK bits for the TTI(s) scheduled by the multi-TTI doesn’t exceed N. [0092] In another option, if the total number of configured CBGs of the TTI(s) scheduled by a multi-TTI DCI for a serving cell is larger than N, time domain bundling, and/or spatial bundling, and/or CBG bundling applies to Y TTI(s) that are scheduled by the multi-TTI DCI, e.g. the last Y TTI(s), while CBG based HARQ-ACK feedback still applies to other TTI(s). Y is the smallest value so that the total number of HARQ-ACK bits for the TTI(s) scheduled by the multi-TTI doesn’t exceed N. [0093] In another option, if the total number of scheduled CBGs of the TTI(s) scheduled by a multi-TTI DCI for a serving cell is larger than N, time domain bundling, and/or spatial bundling, and/or CBG bundling applies to Y TTI(s) that are scheduled by the multi-TTI DCI, e.g. the last Y TTI(s), while CBG based HARQ-ACK feedback still applies to other TTI(s). Y is the smallest value so that the total number of HARQ-ACK bits for the TTI(s) scheduled by the multi-TTI doesn’t exceed N. [0094] Type1 HARQ-ACK codebook [0095] In Rel-15, Type1 HARQ-ACK codebook is generated based on the configured set of K1 values, the configured TDD UL-DL configurations (e.g. tdd-UL-DL-ConfigurationCommon and tdd-UL-DL-ConfigurationDedicated) and the time domain resource allocation (e.g. SLIV) table(s). In Type1 HARQ- ACK codebook, a set of occasions for candidate PDSCH reception are determined. Depending on UE capability, the number of occasions for a slot associated with a value n-K1 is either fixed to 1 or determined by non- overlapped SLIVs in the slot. Type1 HARQ-ACK codebook could be extended to support HARQ-ACK feedback for the multiple TTIs scheduled by a multi-TTI DCI. [0096] In one embodiment, HARQ-ACK for the one or multiple TTIs that is scheduled by a multi-TTI DCI is transmitted on an occasion that is associated with a slot that is scheduled by the multi-TTI DCI. For example, slot n-K1, n is the slot index of PUCCH resource, K1 is indicated in the multi-TTI DCI. The number of HARQ-ACK bits of each occasion could be the configured by a high layer signaling, or determined as the maximum of: x The maximum number of CBGs configured by high layer that can b ^{e scheduled by a single-TTI DCI.} _{x The maximum number of CBGs configured by high layer that can} b ^{e scheduled by a multi-TTI DCI which schedules a single TTI.} _{x Maximum number of TBs scheduled by a multi-TTI DCI. Each} TTI scheduled by the multi-TTI DCI consists one or two TBs. [0097] For the one or more TTIs that is scheduled by a multi-TTI DCI, the HARQ-ACK bits could be generated by time domain bundling, and/or spatial bundling, and/or CBG bundling, and/or generated assuming CBG based HARQ- ACK feedback is limited to single scheduled TTI or can be allowed to multiple scheduled TTIs, as disclosed in above embodiments. [0098] In one option, if the multiple TTIs that is scheduled by a multi- TTI DCI occupy N consecutive slots and the same SLIV applies in each of the N slots, e.g. the same as PDSCH with pdsch-AggregationFactor of N in Rel-15, the HARQ-ACKs of the one or multiple TTIs scheduled by a multi-TTI DCI could be placed in the Type1 codebook in an occasion that is determined in the same way as PDSCH with pdsch-AggregationFactor of N and with same SLIV. [0099] FIG.12 illustrates one example of such time resource allocation of multi-TTI scheduling. The same SLIV a applies to each of the 4 slots scheduled by the multi-TTI DCI and different TBs are transmitted in different slots. The occasion of candidate PDSCH reception is determined as if it is a PDSCH with pdsch-AggregationFactor 4 and with SLIV a. [00100] In another option, for a row of TDRA table, different SLIVs may be configured in the multiple slots that are scheduled by a multi-TTI DCI, and/or multiple SLIVs may be configured in a slot that is scheduled by the multi-TTI DCI, such SLIV configuration impacts Type1 HARQ-ACK codebook. In addition to the existing principles in Type1 HARQ-ACK codebook in Rel-15, to determine whether an occasion needs to be reserved for a row of the TDRA table, the SLIV(s) in each slot corresponding to the row need to be verified. If at least X SLIV(s) in one or more slots corresponding to the row is available for PDSCH transmission, an occasion needs to be reserved for the row. X could be a fixed value, e.g.1, or X can be configured by high layer signaling. The occasion for HARQ-ACK bits for the row is associated with a slot, e.g. slot n-K1. To allocate occasion(s) for the slot, the SLIV of the row in the slot is considered available for potential PDSCH transmission. Finally, the number of occasions for the slot equals to the maximum number of non-overlapped available SLIVs in the slot. If there are multiple SLIVs of the row is configured in the slot, occasion(s) can be allocated for one or all of the SLIVs. Depending on UE capability, if at least one row is available for potential PDSCH transmission, only one occasion is allocated for the slot. [00101] FIG.13 illustrates one example of a row of TDRA table for multi-TTI scheduling. An occasion of candidate PDSCH reception is allocated and associated with the last slot (e.g. slot n-K1) that is scheduled by the multi- TTI DCI if at least one SLIV out of the four SLIVs is available for PDSCH transmission, where n is slot index of PUCCH, K1 is indicated by the multi-TTI DCI. A SLIV may be considered as available if it is not overlapped with a UL symbol indicated by TDD UL-DL configuration. [00102] In one embodiment, assuming each TTI that is scheduled by a multi-TTI DCI must correspond to a slot n-K1, n is the slot index of PUCCH resource, HARQ-ACK for a TTI in a slot that is scheduled by the multi-TTI DCI is transmitted on an occasion that is determined by the SLIV of the TTI of the slot. The occasion(s) of the slot could be determined in a same way as that for Type1 HARQ-ACK codebook for single-TTI scheduling in Rel-15. CBG based HARQ-ACK feedback, if configured, applies to each TTI that is scheduled by a multi-TTI DCI. [00103] FIG.14 illustrates one example of such HARQ-ACK codebook design. It is assumed that the configured set of K1 is {9, 7, 6, 4, 2} and maximum number of TTIs that can be scheduled by multi-TTI DCI is 4. A multi-TTI DCI 1 can schedule four TTIs in slot n-9, n-7, n-6 and n-4 and indicate K1 value 4. If gNB decides to schedule only three TTIs, gNB may use a multi-TTI DCI 2 that schedules three TTIs in slot n-9, n-7 and n-6 and indicate K1 value 6. A multi-TTI DCI 3 can schedule three TTIs in slot n-6, n-4 and n-2 and indicate K1 value 2. HARQ-ACK for the TTI n-9, n-7, n-6, n-4 and n-2 if scheduled are respectively transmitted in the occasion determined for slot n-9, n- 7, n-6, n-4 and n-2. [00104] Type2 HARQ-ACK codebook [00105] A dynamic HARQ-ACK codebook could be generated considering multi-TTI scheduling for PDSCH transmissions with multiple TBs. In Rel-15, two sub-codebooks are generated and concatenated to form the final HARQ-ACK codebook. One sub-codebook carries HARQ-ACK for all TB- based PDSCH scheduling, e.g. one or two HARQ-ACK bits are reported for each PDSCH. Whenever at least one cell or BWP is configured with PDSCH transmission with 2 TBs, UE generates two HARQ-ACK bits for each PDSCH. The other sub-codebook is for CBG based PDSCH scheduling. The different cells or BWPs may be configured with different number of CBGs per PDSCH. Therefore, the number of HARQ-ACK bits per PDSCH equals to the maximum number of CBGs per PDSCH among all configured cells or BWPs. The counter DAI and total DAI could still count the number of PDCCHs which schedules PDSCH transmissions belonging to the same sub-codebook. Note: A single-TTI DCI can only schedule one TTI, while a multi-TTI DCI may schedule a single TTI or multiple TTIs dynamically. [00106] In one embodiment, to support multi-TTI scheduling by a multi- TTI DCI, two sub-codebooks can be generated too. The first sub-codebook carries HARQ-ACK bits for a PDCCH that is associated with one or two HARQ-ACK bits. Alternatively, the first sub-codebook carries HARQ-ACK bit for a PDCCH that is associated with only one HARQ-ACK bit. The PDSCH in the first sub-codebook may be limited to TB-based transmission that is scheduled by single-TTI DCI. If only one PDSCH is scheduled by a multi-TTI DCI, the HARQ-ACK bit(s) for the PDSCH can be included in the first sub- codebook. Alternatively, If no more than two PDSCHs are scheduled by a multi- TTI DCI and the number of HARQ-ACK bit(s) for the PDSCH(s) are not more than two, the HARQ-ACK bit(s) for the PDSCH(s) can be included in the first sub-codebook. The second sub-codebook carries HARQ-ACK bits for all other PDSCH transmissions. Alternatively, a second sub-codebook carries HARQ- ACK bits for all other PDSCH transmissions that are scheduled by a multi-TTI DCI, while a third sub-codebook carries HARQ-ACK bits for all PDSCH transmissions with CBG based transmissions. Further, a cell configured with CBG based transmission and a cell configured with multi-PDSCH scheduling may not be simultaneously configured in the same PUCCH cell group of the UE. [00107] In one embodiment, in the HARQ-ACK codebook consisting one or more sub-codebooks, for the one or more TTIs that is scheduled by a multi- TTI DCI, the HARQ-ACK bits could be generated by time domain bundling, and/or spatial bundling, and/or CBG bundling, and/or generated assuming CBG based HARQ-ACK feedback is limited to single scheduled TTI or can be allowed to multiple scheduled TTIs, as disclosed in above embodiments. For example, if M PDSCHs are scheduled by a DCI, N HARQ-ACK bits can be obtained for the M PDSCHs by time domain bundling schemes as disclosed in above embodiments, . HARQ-ACK bundling may be performed only when the number of HARQ-ACK bits for the PDSCHs or the number of the PDSCHs that are scheduled by a multi-TTI DCI exceeds a threshold. For the PDSCH that is scheduled by a single-TTI DCI, spatial bundling and/or CBG bundling can be applied to reduce the number of HARQ-ACK bits too. Whether the HARQ-ACK information for the PDSCH(s) that is scheduled by a DCI is included in the first or second sub-codebook could be determined by the number of bundled bits for a DCI. [00108] In one option, if the number of bundled HARQ-ACK bits for a DCI is 1, the bundled bit is included in the first sub-codebook. Otherwise, the bundled bits are included in the second sub-codebook. [00109] In another option, if the number of bundled HARQ-ACK bits for a DCI is no more than 2, the bundled bit(s) are included in the first sub- codebook. Otherwise, the bundled bits are included in the second sub-codebook. [00110] In another option, in case that one TB per PDSCH is configured on all the serving cells, if the number of bundled HARQ-ACK bits for a DCI is 1, the bundled bit is included in the first sub-codebook. Otherwise, the bundled bits are included in the second sub-codebook. [00111] In another option, in case that one TB per PDSCH is configured on all the serving cells that are not configured with multi-TTI scheduling, if the number of bundled HARQ-ACK bits for a DCI is 1, the bundled bit is included in the first sub-codebook. Otherwise, the bundled bits are included in the second sub-codebook. [00112] In another option, in case that two TBs per PDSCH is configured on at least one serving cell, if the number of bundled HARQ-ACK bits for a DCI is no more than two, the bundled bit(s) are included in the first sub-codebook. Otherwise, the bundled bits are included in the second sub-codebook. [00113] In another option, in case that two TBs per PDSCH is configured on at least one serving cell that is not configured with multi-TTI scheduling, if the number of bundled HARQ-ACK bits for a DCI is no more than two, the bundled bit(s) are included in the first sub-codebook. Otherwise, the bundled bits are included in the second sub-codebook. [00114] In another option, irrespective of whether or not HARQ-ACK bundling can be applied to the HARQ-ACK bits for the one or more PDSCHs that are scheduled by a multi-TTI DCI, only for the case that one PDSCH is scheduled by a multi-TTI DCI, the HARQ-ACK bit(s) for the PDSCH can be included in the first sub-codebook. Otherwise, the bundled bit(s) are included in the second sub-codebook. [00115] In another option, irrespective of whether or not HARQ-ACK bundling can be applied to the HARQ-ACK bits for the one or more PDSCHs that are scheduled by a multi-TTI DCI, the HARQ-ACK bit(s) for the PDSCH(s) can be included in the second HARQ-ACK sub-codebook. [00116] In one embodiment, if the maximum number of PDSCHs among all entries of TDRA table is two, a single HARQ-ACK codebook can be generated to carry HARQ-ACK bits for all the PDSCH transmissions on all the configured serving cells, at least for the case that CBG based transmission is not configured on any serving cell.2 bits are associated with each DCI in the single HARQ-ACK codebook. Further, if there is a cell configured with CBG based transmission, the HARQ-ACK bits for the CBGs of a PDSCH that is scheduled by a DCI configured with CBG based scheduling can be included in a second HARQ-ACK sub-codebook. HARQ-ACK bits for all other DCIs are included in the first HARQ-ACK sub-codebook. [00117] In one embodiment, to support multi-TTI scheduling by a multi- TTI DCI, whether a single HARQ-ACK codebook or two HARQ-ACK sub- codebooks are used can be determined by the HARQ-ACK bundling scheme and/or the maximum number of bundled bits for the one or multiple PDSCHs that are scheduled by a multi-TTI DCI. The above bundling scheme can be time domain bundling, spatial bundling, CBG bundling, or a combination of the three bundling schemes, as disclosed in above embodiments. Further, a UE may not expect the configuration of multi-TTI scheduling with HARQ-ACK bundling and CBG based transmission in the same or different serving cells. Alternatively, a UE may not expect the configuration of multi-TTI scheduling with HARQ- ACK bundling and CBG based transmission in the same or different serving cells in a PUCCH cell group. Alternatively, a second sub-codebook carries HARQ-ACK bits for the PDSCH transmissions that are scheduled by a multi- TTI DCI, while a third sub-codebook carries HARQ-ACK bits for all PDSCH transmissions with CBG based transmissions. [00118] The following options can be used to determine the case to generate single HARQ-ACK codebook or two HARQ-ACK sub-codebooks, at least for the case that CBG based transmission is not configured on any serving cell. On the other hand, if there is a cell configured with CBG based transmission, the HARQ-ACK bits for the CBGs of a PDSCH that is scheduled by a DCI configured with CBG based scheduling can be included in a second HARQ-ACK sub-codebook. [00119] In one option, for the one or multiple PDSCHs that are scheduled by a multi-TTI DCI, the HARQ-ACK bits for the multiple PDSCHs are bundled into one bit, then a single HARQ-ACK codebook can be generated to carry HARQ-ACK bits for all the PDSCH transmissions on all the configured serving cells. One HARQ-ACK bit could be generated for each DCI in the single HARQ-ACK codebook if single TB per PDSCH or spatial bundling is configured on all serving cells that are not configured with multi-TTI scheduling. Otherwise, 2 bits are associated with each DCI in the single HARQ- ACK codebook. If the maximum number of bundled HARQ-ACK bits associated with one DCI is larger than one, two HARQ-ACK sub-codebooks can be generated and concatenated to form the final HARQ-ACK codebook. [00120] In one option, for the one or multiple PDSCHs that are scheduled by a multi-TTI DCI, the HARQ-ACK bits for the multiple PDSCHs are bundled into at most two bits, then a single HARQ-ACK codebook can be generated to carry HARQ-ACK bits for all the PDSCH transmissions on all the configured serving cells. The number of bits that is associated with each DCI in the single HARQ-ACK codebook is the maximum number of bits per DCI. If the maximum number of bundled HARQ-ACK bits associated with one DCI is larger than two, two HARQ-ACK sub-codebooks can be generated and concatenated to form the final HARQ-ACK codebook. [00121] In one option, if one TB per PDSCH is configured on all the serving cells, and if the HARQ-ACK bits for the one or multiple PDSCHs that are scheduled by a multi-TTI DCI are bundled into one bit, a single HARQ-ACK codebook can be generated to carry HARQ-ACK bits for all the PDSCH transmission on all the configured serving cells. One HARQ-ACK bit could be generated for each DCI in the single HARQ-ACK codebook. On the other hand, if at least one serving cell is configured with PDSCH transmission with two TBs per PDSCH, and if the HARQ-ACK bits for the one or multiple PDSCHs that are scheduled by a multi-TTI DCI are bundled into at most two bits, a single HARQ-ACK codebook can be generated to carry HARQ-ACK bits for all the PDSCH transmission on all the configured serving cells. Two bits are associated with each DCI in the single HARQ-ACK codebook. In other cases, two HARQ- ACK sub-codebooks can be generated and concatenated to form the final HARQ-ACK codebook. [00122] In one option, if one TB per PDSCH is configured on all the serving cells that are not configured with multi-TTI scheduling, and if the HARQ-ACK bits for the one or multiple PDSCHs that are scheduled by a multi- TTI DCI are bundled into one bit, a single HARQ-ACK codebook can be generated to carry HARQ-ACK bits for all the PDSCH transmission on all the configured serving cells. One HARQ-ACK bit could be generated for each DCI in the single HARQ-ACK codebook. On the other hand, if two TBs per PDSCH is configured on at least one serving cell that is not configured with multi-TTI scheduling, and if the HARQ-ACK bits for the one or multiple PDSCHs that are scheduled by a multi-TTI DCI are bundled into at most two bits, a single HARQ-ACK codebook can be generated to carry HARQ-ACK bits for all the PDSCH transmission on all the configured serving cells. Two bits are associated with each DCI in the single HARQ-ACK codebook. In other cases, two HARQ- ACK sub-codebooks can be generated and concatenated to form the final HARQ-ACK codebook. [00123] In one embodiment, a parameter, denoted as harq-ACK- TimeBundling can be configured by high layer signaling to control the HARQ- ACK bundling in time. harq-ACK-TimeBundling may include a sub-field of Boolean value that indicates whether time bundling is applied or not, plus a sub- field which indicates the maximum number of bundled bits per DCI or the maximum number of PDSCH corresponding to a bundled bit. Alternatively, harq-ACK-TimeBundling indicate a Boolean value on whether time bundling is applied or not, while the maximum number of bundled bits per DCI or the maximum number of PDSCH corresponding to a bundled bit can be predefined, e.g. maximum one bundled bit. Alternatively, harq-ACK-TimeBundling indicates the maximum number of bundled bits per DCI or the maximum number of PDSCHs corresponding to a bundled bit, with a special value indicating that time bundling is not applicable. For example, the configurable maximum number of bundled bits per DCI is {1, 2, 4, NoTimeBundling}. [00124] The configuration of time domain HARQ-ACK bundling could be common to the multiple PUCCH cell groups for a UE. Alternatively, time domain HARQ-ACK bundling could be separately configured for each PUCCH cell group for a UE. Alternatively, the configuration of time domain HARQ- ACK bundling can be configured separately for each cell configured with multi- PDSCH scheduling. Alternatively, the configuration of time domain HARQ- ACK bundling can be configured separately for each DL BWP of each cell configured with multi-PDSCH scheduling. [00125] If a UE is configured for at least two simultaneously constructed HARQ-ACK codebooks, the configuration of time domain HARQ-ACK bundling could be separately configured for each HARQ-ACK codebook. For example, the list of time domain HARQ-ACK bundling IE can be configured in PhysicalCellGroupConfig for a PUCCH cell group. [00126] In one option, the configuration of time bundling can be separately configured for a PUCCH cell group by harq-ACK-TimeBundling, in addition to the configuration of spatial bundling of the PUCCH cell group, e.g., by the existing parameter harq-ACK-SpatialBundling. [00127] If harq-ACK-SpatialBundling is set to true , spatial bundling of HARQ-ACK feedback is applied in all serving cells including the cells configured with multi-PDSCH scheduling, if two TBs per PDSCH are configured on the cells. [00128] If harq-ACK-TimeBundling is configured, time bundling of HARQ-ACK feedback is applied to all serving cells that are configured with multi-PDSCH scheduling. For a cell configured with two TBs per PDSCH, the timing bundling separately applies to the TBs with same index among the multiple PDSCHs that are scheduled by a multi-TTI DCI if spatial bundling is not enabled. [00129] In another option, the configuration of time bundling and spatial bundling, if applicable, can be separately configured for a PUCCH cell group by harq-ACK-TimeBundling, in addition to the configuration of spatial bundling of the PUCCH cell group, e.g., by the existing parameter harq-ACK- SpatialBundling. [00130] If harq-ACK-SpatialBundling is set to ‘true’, spatial bundling of HARQ-ACK feedback is applied in all serving cells including the cells configured with multi-PDSCH scheduling, if two TBs per PDSCH are configured on the cells. [00131] If harq-ACK-TimeBundling is configured, time bundling is applied to a serving cell that are configured with multi-PDSCH scheduling. If the cell is configured with two TBs per PDSCH, spatial bundling is applied too. [00132] In another option, the configuration of time domain HARQ-ACK bundling could be common for HARQ-ACK transmission on PUCCH and PUSCH. On the other hand, the configuration of spatial bundling can be still separately configured for HARQ-ACK transmission on PUCCH and PUSCH. By this scheme, the sub-codebook used to carry the HARQ-ACK information that is associated with a DCI is not impacted by PUCCH or PUSCH for HARQ- ACK transmission. [00133] In another option, the configuration of time domain HARQ-ACK bundling for HARQ-ACK transmission on PUCCH or PUSCH can be configured separately, e.g., by harq-ACK-TimeBundlingPUCCH or harq-ACK- TimeBundlingPUSCH. The configuration of spatial bundling can be still separately configured for HARQ-ACK transmission on PUCCH and PUSCH. [00134] In this option, the sub-codebook carrying the HARQ-ACK information that is associated with a DCI can be always determined by assuming HARQ-ACK transmission on PUCCH. When HARQ-ACK is transmitted on PUSCH, the number of HARQ-ACK bits per DCI for the second sub-codebook, if existed, can be determined by the parameter harq-ACK-TimeBundlingPUSCH. The number of HARQ-ACK bits per DCI for the first sub-codebook is unchanged. Alternatively, the sub-codebook carrying the HARQ-ACK information that is associated with a DCI can be always determined by assuming HARQ-ACK transmission on a UL channel, which results in the largest number of HARQ-ACK bits per DCI. For example, if the number of bundled HARQ- ACK bits is 4 bits per DCI according to harq-ACK-TimeBundlingPUSCH and the number of bundled HARQ-ACK bits is 2 bits per DCI according to harq- ACK-TimeBundlingPUCCH, the UL channel for sub-codebook determination is PUSCH. In another example, if the number of bundled HARQ-ACK bits is 4 bits per DCI according to harq-ACK-TimeBundlingPUCCH and the number of bundled HARQ-ACK bits is 2 bits per DCI according to harq-ACK- TimeBundlingPUSCH, the UL channel for sub-codebook determination is PUCCH. When HARQ-ACK is transmitted on PUSCH, the number of HARQ- ACK bits per DCI for the second sub-codebook, if existed, can be determined by the parameter harq-ACK-TimeBundlingPUSCH. When HARQ-ACK is transmitted on PUCCH, the number of HARQ-ACK bits per DCI for the second sub-codebook, if existed, can be determined by the parameter harq-ACK- TimeBundlingPUCCH. The number of HARQ-ACK bits per DCI for the first sub-codebook is unchanged. [00135] Alternatively, irrespective of the configuration timing bundling for HARQ-ACK transmission, only for the case that one PDSCH is scheduled by a multi-TTI DCI, the HARQ-ACK bit(s) for the PDSCH can be included in the first sub-codebook. Otherwise, based on the configuration harq-ACK- TimeBundling, the corresponding HARQ-ACK bit(s) for the PDSCHs scheduled by a multi-TTI DCI are included in the second sub-codebook. By this way, the sub-codebook used to carry the HARQ-ACK information that is associated with a DCI is not impacted by PUCCH or PUSCH for HARQ-ACK transmission. The number of HARQ-ACK bits per DCI for the second sub-codebook can be determined by harq-ACK-TimeBundlingPUCCH for HARQ-ACK transmission on PUCCH, or by harq-ACK-TimeBundlingPUSCH for HARQ-ACK transmission on PUSCH respectively. [00136] In another option, if a UE is configured with UCI multiplexing for PUCCH or PUSCH different priorities, e.g. HARQ-ACK for low priority can be multiplexed with HARQ-ACK for high priority, or HARQ-ACK for low priority can be multiplexed with PUSCH with high priority, the configuration timing bundling for HARQ-ACK transmission could be separately configured for the case of UCI multiplexing for PUCCH/PUSCH with same priority and the case of UCI multiplexing for PUCCH/PUSCH with different priority, respectively. By separate configuration, different UCI performance requirement for different priority and different multiplexing scheme can be achieved. [00137] Some embodiments are directed to a user equipment (UE). In these embodiments, the UE is configured to decode a physical downlink control channel (PDCCH) carrying a multi-transmission time interval (TTI) downlink control information (DCI) received from a gNode B (gNB). The multi-TTI DCI may schedule two or more physical downlink shared channels (PDSCHs). Each scheduled PDSCH may comprise at least one transport block (TB). An example of this is illustrated in FIG.2B. In these embodiments, the UE may encode a HARQ-ACK codebook for the two or more PDSCHs for transmission on an uplink channel. To generate the HARQ-ACK codebook, the UE may apply time- domain bundling to HARQ-ACK information (i.e., for the two or more PDSCHs scheduled by the multi-TTI DCI such that the HARQ-ACK information for two or more of the PDSCHs is bundled into one bit (i.e., a single bit). The UE may store the HARQ-ACK codebook in memory. [00138] In these embodiments, the HARQ-ACK bits may be generated by time-domain bundling. These embodiments are discussed in more detail below. In some embodiments, the HARQ-ACK bits may be generated by performing both time-domain bundling and spatial-domain bundling. These embodiments are also discussed in more detail below. In some embodiments, the HARQ-ACK bits may be generated by performing either time-domain bundling or spatial- domain bundling. [00139] In these embodiments, each scheduled PDSCH may comprise at least one TB which may be scheduled in different slots or scheduled in the same slot. In some MIMO embodiments, each scheduled PDSCH may comprise two TBs which may be scheduled in different slots or in the same slot. In these embodiments, time-domain bundling is applied to the HARQ-ACK information for all two or more PDSCHs scheduled by the multi-TTI DCI. [00140] In some embodiments, the HARQ-ACK codebook for the two or more PDSCHs is encoded for transmission on a physical uplink control channel (PUCCH), although the scope of the embodiments is not limited in this respect as the HARQ-ACK codebook for the two or more PDSCHs may be encoded for transmission on a physical uplink shared channel (PUSCH). [00141] In some embodiments, the UE may apply the time-domain bundling to bits of HARQ-ACK information for one or more higher-frequency cells and may to refrain from applying the time-domain bundling to bits of HARQ-ACK information for one or more lower-frequency cells. In these embodiments, the one or more higher-frequency cells comprising cells may operate above a 52.6 GHz carrier frequency and the one or more lower- frequency cells comprising cells may operate below a 52.6 GHz carrier frequency. In some of these embodiments, higher-frequency cells (i.e., cells operating above a 52.6 GHz carrier frequency) may utilize a subcarrier spacing (SCS) of 120 kHz, 480 kHz and/or 960 kHz, although the scope of the embodiments is not limited in this respect as a SCS of 1.92 MHz or 3.84 MHz mays as be used. [00142] In some embodiments, the UE may be configured with at least two of the higher-frequency cells including a first higher-frequency cell and a second higher-frequency cell. Based on configuration information from the gNB the UE may be configured to apply the time-domain bundling to bits of HARQ- ACK information for two or more PDSCHs associated with the first higher- frequency cell and refrain from applying the time-domain bundling to bits of HARQ-ACK information for two or more PDSCHs associated with the second higher-frequency cell. In these embodiments, if there are multiple higher- frequency cells, the gNB can separately configure the application of time bundling or not for each cell. [00143] In some embodiments, the UE may be configured for carrier aggregation (CA) with a first of the higher-frequency cells and with a first of the lower-frequency cells. In these embodiments, the UE may apply time-domain bundling to bits of HARQ-ACK information for two or more PDSCHs of the first of the higher-frequency cells and may refrain from time-domain bunding bits of HARQ-ACK information for two or more PDSCHs of the first of the lower-frequency cells. In these embodiments, the UE may generate the HARQ- ACK codebook by including the time-domain bundled bits of HARQ-ACK information for the first of the higher-frequency cells and the non-time-domain bundled bits of HARQ-ACK information for the first of the lower-frequency cells. [00144] In these embodiments, regardless of whether or not time-domain bundling is performed, spatial-domain bunding may be performed for HARQ- ACK information for PDSCHs of the lower-frequency cell and the higher- frequency cell. [00145] In some embodiments, for the time-domain bundling, the UE may bundle the HARQ-ACK information for each (i.e., all) of the PDSCHs scheduled by the multi-TTI DCI into a single bit. These embodiments are illustrated in FIG.3A. In these embodiments, each PDSCH may have one HARQ-ACK and the HARQ-ACK information for each of the PDSCHs may be time-domain bundled into a single bit. In the embodiments illustrated in FIG.3A, the HARQ- ACK for all the PDSCHs scheduled by the multi-TTI DCI are bundled into a single bit. In one example, when the UE is configured for MIMO with more than four layers, each PDSCH may have two HARQ-ACK bits. In these embodiments, the HARQ-ACK bits from each PDSCH may be bundled into a single bit. [00146] In some embodiments, when each of the PDSCHs scheduled by the multi-TTI DCI is scheduled with more than one TB on more than one spatial codeword (CW), the UE may apply the time-domain bundling across all the TBs of each respective CW. In these embodiments, the HARQ-ACK information bits for the first CW (CW#0) for all the PDSCHs scheduled by the multi-TTI DCI are bundled into a first single bit, the HARQ-ACK information bits for the second CW (CW#1) for all the PDSCHs scheduled by the multi-TTI DCI are bundled into a second single bit, etc. An example of these embodiments is illustrated in FIG.3B. [00147] In some embodiments, for the time-domain bundling, the UE may bundle the HARQ-ACK information for subsets of the PDSCHs scheduled by the multi-TTI DCI into a single bit, In these embodiments, at least one of the subsets comprises at least two of the PDSCHs. An example of this is illustrated in FIG.4A. In these embodiments, the number of subsets that are bundled into a single bit, and the number of PDSCHs per subset may depend on the number of bundled bits configured to the UE. For example, if number of bundled bits configured is 4 for a DCI that scheduled 8 PDSCHs, each subset has 2 PDSCHs to get 4 bundled bits. For example, if number of bundled bits configured is 4 for a DCI that scheduled 5 PDSCHs, one subset has 2 PDSCHs and three other subsets have a single PDSCH to get 4 bundled bits. For example, if number of bundled bits configured is 4 for a DCI that scheduled 2 PDSCHs, two subsets have a single PDSCH each and 2 padding NACK bits are added to get 4 bundled bits. [00148] In some embodiments, when each PDSCH scheduled by the multi-TTI DCI is scheduled with more than one TB on more than one spatial codeword (CW), the UE may apply the time-domain bundling across subsets of the TBs of each respective CW, at least one of the subsets comprising two or more of the TBs. An example of this is illustrated in FIG.4B. In these embodiments, the number of TBs that are bundled into a single bit may depend on the number of bundled bits configured to the UE. [00149] In some embodiments, when each PDSCH scheduled by the multi-TTI DCI is scheduled with more than one TB on more than one spatial codeword (CW), the UE may apply time-domain and spatial-domain bundling across all the TBs including all CWs into one single bit. An example of these time-domain and spatial-domain bundling embodiments is illustrated in FIG.5. [00150] In some embodiments, when each PDSCH scheduled by the multi-TTI DCI is scheduled with more than one TB on more than one spatial codeword (CW), the UE may apply time-domain and spatial-domain bundling across subsets the TBs including all CW of the TBs of a subset, In these embodiments, at least one of the subsets of the TBs comprise two or more TBs. An example of these time-domain and spatial-domain bundling embodiments is illustrated in FIG.6. [00151] In some embodiments, for transmission of the HARQ-ACK codebook on a physical uplink control channel (PUCCH), the UE may determine a PUCCH occasion for transmission of the HARQ-ACK codebook on a PUCCH resource, the PUCCH occasion associated with a slot scheduled by the multi-TTI DCI. [00152] Some embodiments apply to Type 1 HARQ-ACK codebook with time-domain bundling. In these embodiments, for a Type 1 HARQ-ACK codebook, the UE may determine the PUCCH occasion based on a slot index (n) of the PUCCH resource and a slot offset indicated in the multi-TTI DCI. These embodiments are directed to Type 1 HARQ-ACK codebook with time-domain bundling. [00153] In some embodiments, the UE may generate a first sub-codebook for the HARQ-ACK information when the multi-TTI DCI schedules a single PDSCH or for PDSCH transmissions not scheduled by the multi-TTI DCI and generate a second sub-codebook for the HARQ-ACK information when the multi-TTI DCI schedules the two or more PDSCHs. In these embodiments, the HARQ-ACK codebook may comprise the first and second sub-codebooks. [00154] In some embodiments, when a number of bundled bits of HARQ- ACK information is one, the one bit may be included in the first sub-codebook. In these embodiments, when the number of bundled bits of HARQ-ACK information is greater than one, the bits may be included in the second sub- codebook. [00155] In some embodiments, for two PDSCHs comprising a first and a second PDSCH and each PDSCH with one TB, when the UE is configured to bundle the HARQ-ACK information for the two the PDSCHs into the one bit, the one bit may be encoded to indicate an ACK when the HARQ-ACK information for both the first and second PDSCHs are an ACK and the one bit encoded to indicate a negative ACK (NACK) when the HARQ-ACK information for either or both the first and second PDSCH are NACK. In these embodiments, the gNB receives a NACK when either one of the first and second PDSCHs are NACK and will therefore need to retransmit both the PDSCHs since the gNB is unable to differentiate which PDSCH was not received properly. [00156] Some embodiments are directed to a non-transitory computer- readable storage medium that stores instructions for execution by processing circuitry of a user equipment (UE). In these embodiments, the processing is configured to decode a physical downlink control channel (PDCCH) carrying a multi-transmission time interval (TTI) downlink control information (DCI) received from a gNode B (gNB). The multi-TTI DCI may schedule two or more physical downlink shared channels (PDSCHs). Each scheduled PDSCH may comprise at least one transport block (TB). In these embodiments, the processing circuitry may encode a HARQ-ACK codebook for the two or more PDSCHs for transmission on an uplink channel. In these embodiments, to generate the HARQ-ACK codebook, the processing circuitry may apply time-domain bundling to HARQ-ACK information such that the HARQ-ACK information for two or more of the PDSCHs is bundled into one bit. [00157] Some embodiments are directed to a gNode B (gNB). In these embodiments, the gNB may encode configuration information for transmission to a user equipment (UE). The configuration information may configure the UE for time-domain bundling of HARQ-ACK information when two or more physical downlink shared channels (PDSCHs) are scheduled by a multi- transmission time interval (TTI) downlink control information (DCI). In these embodiments, the gNB may encode a physical downlink control channel (PDCCH) carrying the multi-TTI DCI. The multi-TTI DCI may schedule the two or more PDSCHs. Each scheduled PDSCH may comprise at least one transport block (TB). The gNB may also decode an uplink channel comprising a HARQ- ACK codebook received from the UE. In these embodiments, the HARQ-ACK codebook is generated by the UE and comprises time-domain bundled bits of HARQ-ACK information for two or more of the PDSCHs scheduled by the multi-TTI DC bundled into one bit. In some embodiments, the gNB may determine whether or not to configure a UE for time-domain bundling of HARQ-ACK information. In these embodiments, the gNB may determine whether or not to configure a UE for time-domain bundling based on CSI reports, previous HARQ-ACK, etc. [00158] In some embodiments, when the UE is configured by the gNB for carrier aggregation (CA) with a higher-frequency cell and a lower-frequency cell, the HARQ-ACK codebook comprises time-domain bundled HARQ-ACK information for two or more PDSCHs of the higher-frequency cell and non-time- domain bundled HARQ-ACK information for two or more PDSCHs of the lower-frequency cell. The higher-frequency cell may be operating above a 52.6 GHz carrier frequency and the lower-frequency cell may be operating below a 52.6 GHz carrier frequency. [00159] In some embodiments, for two PDSCHs comprising a first and a second PDSCH, the HARQ-ACK information for the two the PDSCHs is time- domain bundled into the one bit. In these embodiments, the gNB may configure the gNB to retransmit both the first and the second PDSCH when the one bit indicates a negative ACK (NACK) and configure the gNB to retrain from retransmitting either the first or the second PDSCH when the one bit indicates an ACK. In these embodiments, the gNB receives a NACK when either one of the first and second PDSCHs are NACK and will therefore need to retransmit both the PDSCHs since the gNB is unable to differentiate which PDSCH was not received properly. [00160] FIG.15 illustrates a functional block diagram of a wireless communication device, in accordance with some embodiments. Wireless communication device 1500 may be suitable for use as a UE or gNB configured for operation in a 5G NR network and may be configured to perform the various operations described herein. [00161] The communication device 1500 may include communications circuitry 1502 and a transceiver 1510 for transmitting and receiving signals to and from other communication devices using one or more antennas 1501. The communications circuitry 1502 may include circuitry that can operate the physical layer (PHY) communications and/or medium access control (MAC) communications for controlling access to the wireless medium, and/or any other communications layers for transmitting and receiving signals. The communication device 1500 may also include processing circuitry 1506 and memory 1508 arranged to perform the operations described herein. In some embodiments, the communications circuitry 1502 and the processing circuitry 1506 may be configured to perform operations detailed in the above figures, diagrams, and flows. [00162] In accordance with some embodiments, the communications circuitry 1502 may be arranged to contend for a wireless medium and configure frames or packets for communicating over the wireless medium. The communications circuitry 1502 may be arranged to transmit and receive signals. The communications circuitry 1502 may also include circuitry for modulation/demodulation, upconversion/downconversion, filtering, amplification, etc. In some embodiments, the processing circuitry 1506 of the communication device 1500 may include one or more processors. In other embodiments, two or more antennas 1501 may be coupled to the communications circuitry 1502 arranged for sending and receiving signals. The memory 1508 may store information for configuring the processing circuitry 1506 to perform operations for configuring and transmitting message frames and performing the various operations described herein. The memory 1508 may include any type of memory, including non-transitory memory, for storing information in a form readable by a machine (e.g., a computer). For example, the memory 1508 may include a computer-readable storage device, read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices and other storage devices and media. [00163] In some embodiments, the communication device 1500 may be part of a portable wireless communication device, such as a personal digital assistant (PDA), a laptop or portable computer with wireless communication capability, a web tablet, a wireless telephone, a smartphone, a wireless headset, a pager, an instant messaging device, a digital camera, an access point, a television, a medical device (e.g., a heart rate monitor, a blood pressure monitor, etc.), a wearable computer device, or another device that may receive and/or transmit information wirelessly. [00164] In some embodiments, the communication device 1500 may include one or more antennas 1501. The antennas 1501 may include one or more directional or omnidirectional antennas, including, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas, or other types of antennas suitable for transmission of RF signals. In some embodiments, instead of two or more antennas, a single antenna with multiple apertures may be used. In these embodiments, each aperture may be considered a separate antenna. In some multiple-input multiple-output (MIMO) embodiments, the antennas may be effectively separated for spatial diversity and the different channel characteristics that may result between each of the antennas and the antennas of a transmitting device. [00165] In some embodiments, the communication device 1500 may include one or more of a keyboard, a display, a non-volatile memory port, multiple antennas, a graphics processor, an application processor, speakers, and other mobile device elements. The display may be an LCD screen including a touch screen. [00166] Although the communication device 1500 is illustrated as having several separate functional elements, two or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including digital signal processors (DSPs), and/or other hardware elements. For example, some elements may include one or more microprocessors, DSPs, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), radio-frequency integrated circuits (RFICs) and combinations of various hardware and logic circuitry for performing at least the functions described herein. In some embodiments, the functional elements of the communication device 1500 may refer to one or more processes operating on one or more processing elements. [00167] FIG.16 is a procedure for time-domain bundling HARQ-ACK information in accordance with some embodiments. Procedure 600 may be performed by a user equipment (UE) for time-domain bundling of HARQ-ACK information for two or more PDSCHs scheduled by a multi-TTI DCI. [00168] In operation 602, the UE may decode a physical downlink control channel (PDCCH) carrying a multi-transmission time interval (TTI) downlink control information (DCI) received from a gNode B (gNB). The multi-TTI DCI may schedule two or more physical downlink shared channels (PDSCHs). Each scheduled PDSCH may comprise at least one transport block (TB) [00169] In operation 604, the UE may generate a HARQ-ACK codebook for the two or more PDSCHs scheduled by the multi-TTI DCI by applying time- domain bundling to HARQ-ACK information for the two or more PDSCHs such that the HARQ-ACK information for two or more of the PDSCHs is bundled into one bit. In operation 606, the UE may encode the HARQ-ACK codebook for the two or more PDSCHs for transmission on an uplink channel to the gNB. [00170] Examples: [00171] Example 1 may include a method of wireless communication for HARQ-ACK transmission if one or multiple TTIs is scheduled by a downlink control information (DCI): Decoded, by UE, a DCI from physical downlink control channel (PDCCH); Decoded, by UE, one or more physical downlink shared channels (PDSCH) which are scheduled by the DCI; Transmitted, by UE, a HARQ-ACK codebook which carries HARQ-ACK information for the PDSCH transmissions scheduled by the DCI. [00172] Example 2 may include the method of example 1 or some other example herein, wherein time domain bundling for the HARQ-ACK of the multiple PDSCHs scheduled by a multi-TTI DCI applies. [00173] Example 3 may include the method of example 2 or some other example herein, wherein time domain bundling is done per codeword or together with spatial bundling in a subset of PDSCHs that are scheduled by the DCI. [00174] Example 4 may include the method of example 1 or some other example herein, wherein CBG bundling for the HARQ-ACK is applied to the one or multiple PDSCHs scheduled by a multi-TTI DCI, according to the maximum number of PDSCHs scheduled by a multi-TTI DCI. [00175] Example 5 may include the method of example 1 or some other example herein, wherein CBG bundling for the HARQ-ACK is applied to the one or multiple PDSCHs scheduled by a multi-TTI DCI, according to the actual number of scheduled PDSCHs scheduled by the multi-TTI DCI. [00176] Example 6 may include the method of examples 4 or 5 or some other example herein, wherein CBG bundling is applied to the HARQ-ACK of each subset of configured CBGs of the PDSCH, or of scheduled CBGs of the PDSCH. [00177] Example 7 may include the method of example 4 or some other example herein, wherein CBG bundling is applied to the HARQ-ACK of configured CBGs of one or multiple PDSCHs that are scheduled by a multi-TTI DCI. [00178] Example 8 may include the method of example 5 or some other example herein, wherein CBG bundling is applied to the HARQ-ACK of scheduled CBGs of one or multiple PDSCHs that are scheduled by a multi-TTI DCI. [00179] Example 9 may include the method of example 1 or some other example herein, wherein when only one TTI is scheduled by a multi-TTI DCI, CBG based HARQ-ACK feedback is reported for the TTI; On the other hand, when more than one TTIs are scheduled by the multi-TTI DCI, TB-based HARQ-ACK feedback applies. [00180] Example 10 may include the method of example 1 or some other example herein, wherein denote the number of HARQ-ACK bits associated with a multi-TTI DCI as N, CBG based HARQ-ACK feedback is applied when up to X TTIs are scheduled by a multi-TTI DCI [00181] Example 11 may include the method of example 10 or some other example herein, wherein the multi-TTI DCI includes a CBG transmission information (CBGTI) field only when single TTI is scheduled, or when up to X TTIs are scheduled. [00182] Example 12 may include the method of example 10 or some other example herein, wherein if the number of TTI(s) scheduled by the multi-TTI DCI is no more than X, CBG based HARQ-ACK bits are reported for the TTI(s); otherwise, TB based HARQ-ACK bits are reported for the TTI(s). [00183] Example 13 may include the method of example 10 or some other example herein, wherein if the total number of scheduled CBGs in the TTI(s) is no more than N, CBG based HARQ-ACK bits are reported; otherwise, TB based HARQ-ACK bits are reported. [00184] Example 14 may include the method of example 10 or some other example herein, wherein if the total number of configured CBGs of the TTI(s) is larger than N, TB based HARQ-ACK feedback applies to the last TTI(s), so that the total number of HARQ-ACK bits doesn’t exceed N. [00185] Example 15 may include the method of example 1 or some other example herein, wherein if the total number of scheduled CBGs of the TTI(s) is larger than N, TB based HARQ-ACK feedback applies to the last TTI(s), so that the total number of HARQ-ACK bits doesn’t exceed N. [00186] Example 16 may include the method of example 1, if the total number of configured CBGs of the TTI(s) is larger than N, time domain bundling, and/or spatial bundling, and/or CBG bundling applies to the last TTI(s), so that the total number of HARQ-ACK bits doesn’t exceed N. [00187] Example 17 may include the method of example 1 or some other example herein, wherein if the total number of scheduled CBGs of the TTI(s) is larger than N, time domain bundling, and/or spatial bundling, and/or CBG bundling applies to the last TTI(s), so that the total number of HARQ-ACK bits doesn’t exceed N. [00188] Example 18 may include the method of example 1 or some other example herein, wherein HARQ-ACK for the one or multiple TTIs that is scheduled by a multi-TTI DCI is transmitted on an occasion that is associated with a slot that is scheduled by the multi-TTI DCI in the Type1 codebook. [00189] Example 19 may include the method of example 18 or some other example herein, wherein if the multiple TTIs that is scheduled by a multi-TTI DCI occupy N consecutive slots with the same SLIV, occasion is determined in the same way as PDSCH with pdsch-AggregationFactor of N and with same SLIV. [00190] Example 20 may include the method of example 18 or some other example herein, wherein if at least X SLIV(s) in one or more slots corresponding to a row in TDRA table is available for PDSCH transmission, an occasion is reserved for the row and associated with a slot. [00191] Example 21 may include the method of example 1 or some other example herein, wherein each TTI that is scheduled by a multi-TTI DCI must correspond to a slot n-K1, n is the slot index of PUCCH resource, K1 is feedback delay. [00192] Example 22 may include the method of example 1 or some other example herein, wherein If one or two PDSCHs are scheduled by a multi-TTI DCI, the HARQ-ACK bit(s) for the PDSCH are included in the first sub- codebook. [00193] Example 23 may include the method of example 1 or some other example herein, whether the HARQ-ACK information for the PDSCH(s) that is scheduled by a DCI is included in the first or second sub-codebook is determined by the number of bundled bits for a DCI. [00194] Example 24 may include the method of example 1 or some other example herein, whether a single HARQ-ACK codebook or two HARQ-ACK sub-codebooks are used is determined by the HARQ-ACK bundling scheme and/or the maximum number of bundled bits for the one or multiple PDSCHs that are scheduled by a multi-TTI DCI. [00195] Example 25 may include the method of examples 23 or 24 or some other example herein, wherein if a UE is configured for at least two simultaneously constructed HARQ-ACK codebooks, the configuration of time domain HARQ-ACK bundling is separately configured for each HARQ-ACK codebook. [00196] Example 26 may include the method of examples 23 or 24 or some other example herein, wherein the configuration timing bundling for HARQ-ACK transmission is separately configured for the case of UCI multiplexing for PUCCH/PUSCH with same priority and the case of UCI multiplexing for PUCCH/PUSCH with different priority, respectively. [00197] Example 27 may include the method of examples 23 or 24 or some other example herein, wherein the configuration of time domain HARQ- ACK bundling is common for HARQ-ACK transmission on PUCCH and PUSCH. [00198] Example 28 may include the method of examples 23 or 24 or some other example herein, wherein the configuration of time domain HARQ- ACK bundling for HARQ-ACK transmission on PUCCH or PUSCH is configured separately. [00199] Example 29 may include the method of example 28 or some other example herein, wherein the sub-codebook carrying the HARQ-ACK information that is associated with a DCI is determined by assuming HARQ- ACK transmission on PUCCH. [00200] Example 30 may include the method of example 28 or some other example herein, wherein the sub-codebook carrying the HARQ-ACK information that is associated with a DCI is determined by assuming HARQ- ACK transmission on a UL channel, which results in the largest number of HARQ-ACK bits per DCI. [00201] Example 31 may include the method of example 28 or some other example herein, wherein only for the case that one PDSCH is scheduled by a multi-TTI DCI, the HARQ-ACK bit(s) for the PDSCH is included in the first sub-codebook. [00202] Example 32 may include a method comprising: receiving a downlink control information (DCI) to schedule multiple transmission time intervals (TTIs) for reception of one or more physical downlink shared channels (PDSCHs); receiving the one or more PDSCHs; and encoding, for transmission, a hybrid automatic repeat request (HARQ)-acknowledgement (ACK) codebook that carries HARQ-ACK information for the PDSCHs. [00203] Example 33 may include the method of example 32 or some other example herein, wherein the one or more PDSCHs include multiple PDSCHs, and wherein the HARQ-ACK codebook is encoded using time domain bundling. [00204] Example 34 may include the method of example 33 or some other example herein, wherein time domain bundling is done per codeword or together with spatial bundling in a subset of PDSCHs that are scheduled by the DCI. [00205] Example 35 may include the method of example 32-34 or some other example herein, further comprising applying code block group (CBG) bundling for the HARQ-ACK information for the one or more PDSCHs scheduled. [00206] Example 36 may include the method of example 35 or some other example herein, wherein the CBG bundling is applied based on a maximum number of PDSCHs scheduled by a multi-TTI DCI. [00207] Example 37 may include the method of example 35 or some other example herein, wherein the CBG bundling is applied based on an actual number of the PDSCHs scheduled by the DCI. [00208] Example 38 may include the method of examples 35-37 or some other example herein, wherein the CBG bundling is applied to the HARQ-ACK information of each subset of configured CBGs of the PDSCH, or of scheduled CBGs of the PDSCH. [00209] Example 39 may include the method of example 35-37 or some other example herein, wherein the CBG bundling is applied to the HARQ-ACK information of configured CBGs of the one or more PDSCHs. [00210] Example 40 may include the method of example 35-37 or some other example herein, wherein the CBG bundling is applied to the HARQ-ACK information of scheduled CBGs of the one or multiple PDSCHs. [00211] Example 41 may include the method of example 32-40 or some other example herein, wherein if one or two PDSCHs are scheduled by the DCI, HARQ-ACK bit(s) for the one or two PDSCHs are included in a first sub- codebook. [00212] Example 42 may include the method of example 32-41 or some other example herein, further comprising determining whether the HARQ-ACK information for the one or more PDSCHs is to be included in a first or second sub-codebook based on a number of bundled bits for the DCI. [00213] Example 43 may include the method of example 32-42 or some other example herein, further comprising determining whether to use a single HARQ-ACK codebook or two HARQ-ACK sub-codebooks for the HARQ-ACK information based on a HARQ-ACK bundling scheme and/or a maximum number of bundled bits for the one or more PDSCHs that are scheduled by the DCI. [00214] Example 44 may include the method of examples 42-43 or some other example herein, wherein if a UE is configured for at least two simultaneously constructed HARQ-ACK codebooks, the configuration of time domain HARQ-ACK bundling is separately configured for each HARQ-ACK codebook. [00215] Example 45 may include the method of examples 42-44 or some other example herein, wherein the configuration timing bundling for HARQ- ACK transmission is separately configured for the case of UCI multiplexing for PUCCH/PUSCH with same priority and the case of UCI multiplexing for PUCCH/PUSCH with different priority, respectively. [00216] Example 46 may include the method of examples 42-45 or some other example herein, wherein the configuration of time domain HARQ-ACK bundling is common for HARQ-ACK transmission on PUCCH and PUSCH. [00217] Example 47 may include the method of examples 42-45 or some other example herein, wherein the configuration of time domain HARQ-ACK bundling for HARQ-ACK transmission on PUCCH or PUSCH is configured separately. [00218] Example 48 may include the method of example 47 or some other example herein, wherein the sub-codebook carrying the HARQ-ACK information that is associated with a DCI is determined by assuming HARQ- ACK transmission on PUCCH. [00219] Example 49 may include the method of example 47 or some other example herein, wherein the sub-codebook carrying the HARQ-ACK information that is associated with a DCI is determined by assuming HARQ- ACK transmission on a UL channel, which results in the largest number of HARQ-ACK bits per DCI. [00220] Example 50 may include the method of example 47-49 or some other example herein, wherein only for the case that one PDSCH is scheduled by a multi-TTI DCI, the HARQ-ACK bit(s) for the PDSCH is included in the first sub-codebook. [00221] Example 51 may include the method of example 32-50 or some other example herein, wherein the method is performed by a user equipment (UE) or a portion thereof. [00222] The Abstract is provided to comply with 37 C.F.R. Section 1.72(b) requiring an abstract that will allow the reader to ascertain the nature and gist of the technical disclosure. It is submitted with the understanding that it will not be used to limit or interpret the scope or meaning of the claims. The following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment.