Methods, systems, and apparatus for scheduling subframes and HARQ feedback

Abstract

The invention relates to a method, a system and a device for scheduling subframes and HARQ feedback, in particular to a method, a system and a device for hybrid automatic repeat request (HARQ) processes corresponding to different transmission time interval (TTI) lengths. A wireless transmit / receive unit (WTRU) may link a first HARQ process and a second HARQ process. The WTRU may transmit a first transport block (TB) using a linked first HARQ process and a first HARQ buffer. The WTRU may receive the UL grant, and may determine that the received UL grant is directed to a new transmission for the linked second HARQ process. The WTRU may release the first HARQ buffer based on determining that the received UL grant is directed to a new transmission for the linked second HARQ process. Moreover, the WTRU may generate a second TB for the new transmission, and may store the new TB in a first HARQ buffer. The WTRU may transmit the second TB using the linked second HARQ process and the first HARQ buffer.

Description

This application is a divisional application of Chinese Patent Application No. 202111431874.9, entitled “Method, System and Apparatus for Scheduling Subframes and HARQ Feedback”, filed on February 3, 2017, which is a divisional application of Chinese Patent Application No. 201780009173.1, entitled “Method, System and Apparatus for Scheduling Subframes and Hybrid Automatic Repeat Request (HARQ) Feedback”, filed on February 3, 2017. CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62 / 290,770, filed February 3, 2016, and U.S. Provisional Application No. 62 / 334,759, filed May 11, 2016, the contents of which are incorporated herein by reference. Background Art

[0002] The importance of low-latency cellular communications, including machine-type communications (MTC), is growing rapidly as new applications for cellular technology emerge, such as alarm logging, automotive safety, and factory process control. For example, in Long Term Evolution-Advanced (LTE-A) systems, the typical 1 millisecond time interval (TTI) and associated latency may no longer be sufficient. Existing applications such as gaming and real-time applications such as voice over LTE (VoLTE) and video calling / conferencing will also benefit from reduced latency, for example in terms of perceived quality of experience improvement.

[0003] For a connected wireless transmit / receive unit (WTRU), the total end-to-end delay may be contributed by one or more components. For example, these components may include one or more of the scheduling grant acquisition time, TTI, processing time, and hybrid automatic repeat request (hybrid ARQ or HARQ) round trip time (RTT). If one or more of these components are shortened, the total end-to-end delay can be reduced. Summary of the invention

[0004] Provided herein are methods, systems, and apparatus for uplink (UL) and downlink (DL) transmissions corresponding to different transmission time interval (TTI) lengths, including hybrid automatic repeat request (HARQ) transmissions. For example, the transmissions may be based on configuring a buffer shared by multiple HARQ processes corresponding to at least nTTIs having a normal transmission time interval (nTTI) length and sTTIs having a short TTI (sTTI) length that is shorter than the nTTI length.

[0005] In one example, a wireless transmit / receive unit (WTRU) may link a first HARQ process and a second HARQ process, wherein the first HARQ process is associated with a first HARQ buffer and a first TTI length, and the second HARQ process is associated with the first HARQ buffer and a second TTI length. The WTRU may transmit a first transport block (TB) using the linked first HARQ process and the first HARQ buffer. Further, the WTUR may receive an UL grant. And, the WTRU may determine whether the received UL grant is for a new transmission associated with the linked second HARQ process. Then, the WTRU may release the first HARQ buffer based on determining that the received UL grant is for a new transmission associated with the linked second HARQ process. In addition, the WTRU may generate a second TB for the new transmission, and may store the new TB in the first HARQ buffer. Further, the WTRU may transmit the second TB using the linked second HARQ process and the first HARQ buffer.

[0006] In one example, the first TB and the second TB may be medium access control (MAC) protocol data units (PDUs).Furthermore, the first TB may contain data associated with a first TTI, and the second TB may contain data associated with a second TTI.

[0007] In an additional example, the WTRU may link a first HARQ process with a second HARQ process, wherein the first HARQ process is associated with a first HARQ buffer and a first TTI length, and the second HARQ process is associated with the first HARQ buffer and a second TTI length. Further, the WTRU may use the linked first HARQ process and the first HARQ buffer to receive data regarding a first TB. The WTRU may also receive a DL grant. The WTRU may then determine that the received DL grant is for receiving a new transmission associated with the linked second HARQ process. Further, the WTRU may release the first HARQ buffer based on determining that the received DL grant is for receiving a new transmission associated with the linked second HARQ process. And, the WTRU may use the linked second HARQ process and the first HARQ buffer to receive data regarding a second TB of the new transmission. Further, the WTRU may replace the data in the first HARQ buffer with the received data regarding the second TB.

[0008] In another example, the HARQ buffer may be used for soft combining. For example, the first HARQ buffer may be used for soft combining processing. In an additional example, the HARQ buffer may be located in a soft buffer memory. For example, the first HARQ buffer may be located in a soft buffer memory.

[0009] In an additional example, the WTRU may receive a time division duplex (TDD) UL / DL subframe configuration. Further, the WTRU may receive a DL grant with an indication to use a special subframe for a physical uplink control channel (PUCCH) transmission. The WTRU may then dynamically determine which subframe to switch to the special subframe. The WTRU may switch the subframe to the special subframe. Further, the WTRU may determine a special subframe configuration for the determined special subframe. And, the WTRU may determine resources of the determined special subframe for the PUCCH.

[0010] The WTRU may then determine PUCCH resources and PUCCH design parameters for the PUCCH. Furthermore, the WTRU may transmit HARQ feedback on a PUCCH in the UL portion of the determined resources of the determined special subframe with the determined special subframe configuration using the determined PUCCH resources and PUCCH design parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] A more detailed understanding may be obtained from the following description given by way of example in conjunction with the accompanying drawings, in which:

[0012] Figure 1A is a system diagram of an example communication system in which one or more disclosed embodiments may be implemented;

[0013] Figure 1B Yes, you can Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) used within the communication system shown;

[0014] Figure 1C Yes, you can Figure 1A A system diagram of an example radio access network and an example core network used within the communication system shown;

[0015] Figure 2 is a table showing an example of a time division duplex (TDD) uplink (UL) / downlink (DL) configuration.

[0016] Figure 3 is a table showing a special subframe configuration example.

[0017] Figure 4 is a table showing an example of a special subframe configuration in symbol units;

[0018] Figure 5A is a table showing an example of UL-DL configuration for a transmission time interval (TTI) on a slot basis;

[0019] Figure 5B is a diagram showing an example of sending hybrid automatic repeat request (HARQ) feedback on a switched special subframe in a configuration supporting short TTI (sTTI);

[0020] Figure 6 is a table showing examples of HARQ feedback delays with and without short physical uplink control channel (sPUCCH) transmission in an uplink pilot time slot (UpPTS) of a special subframe;

[0021] Fig. 7A is a diagram showing an example of transmitting HARQ feedback on a physical uplink control channel (PUCCH) in a UL portion of a determined resource of a determined special subframe having a determined special subframe configuration;

[0022] Figure 7B is a diagram showing an example of a guard band physical resource block (PRB) configuration for HARQ feedback;

[0023] Figure 8 is a diagram showing an example of a TDD configuration for guard band PRBs (G-PRBs) based on a TDD configuration for system bandwidth PRBs (S-PRBs);

[0024] Fig. 9 is a diagram showing an example of a timing offset between an S-PRB and a G-PRB;

[0025] Fig.10 is a diagram showing an example of a HARQ feedback resource determination process;

[0026] Fig.11 is a diagram showing an example of separate HARQ processes and HARQ buffers for two TTI lengths;

[0027] Fig.12 is a diagram showing another example of separate HARQ processes and HARQ buffers for two TTI lengths;

[0028] Fig.13 is a diagram showing examples of linking or sharing HARQ processes, HARQ buffers, or both between two TTI lengths;

[0029] Fig.14is a diagram showing an example timeline for use of multiple TTI lengths;

[0030] Fig.15 is a diagram showing another example of HARQ processes, buffers, or both that may be linked, shared, or overlapped;

[0031] Fig.16 is a diagram showing another example of linking, sharing or overlapping HARQ processes, buffers, or both;

[0032] Fig.17 is a diagram showing yet another example of linking, sharing or overlapping HARQ processes, buffers, or both;

[0033] Fig.18 is a diagram showing another example of utilizing dynamic indications to link, share, or overlap HARQ processes, buffers, or both; and

[0034] Fig.19 is a diagram showing an example of a HARQ buffer shared by different HARQ processes. DETAILED DESCRIPTION

[0035] Figure 1A is a diagram of an exemplary communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may allow multiple wireless users to access such content by sharing system resources including wireless bandwidth, and as an example, the communication system 100 may use one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), etc.

[0036] like Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network 106, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, although it should be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network components. Each WTRU 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. For example, the WTRUs 102a, 102b, 102c, 102d may be configured to transmit and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a consumer electronic device, and the like.

[0037] The communication system 100 may also include a base station 114a and a base station 114b. Each base station 114a, 114b may be any type of device configured to facilitate access to one or more communication networks, such as the core network 106, the Internet 110, and / or other networks 112, by wirelessly interfacing with at least one WTRU 102a, 102b, 102c, 102d. The base stations 114a, 114b may be, by way of example, a base transceiver station (BTS), a Node B, an eNode B, a Home Node B, a Home eNode B, a site controller, an access point (AP), a wireless router, and the like. Although each base station 114a, 114b is depicted as a single component, it should be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network components.

[0038] The base station 114a may be part of the RAN 104, which may also include other base stations and / or network components (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals within a specific geographic area called a cell (not shown). The cell may be further divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, that is, each transceiver corresponds to a sector of the cell. In another embodiment, the base station 114a may use multiple-input multiple-output (MIMO) technology, and thus multiple transceivers may be used for each sector in the cell.

[0039] The base stations 114a, 114b may communicate with one or more WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0040] More specifically, as described above, the communication system 100 may be a multiple access system and may use one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. As an example, the base station 114a in the RAN 104 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use Wideband CDMA (WCDMA) to establish the air interface 116. WCDMA may include communication protocols such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink Packet Access (HSDPA) and / or High Speed ​​Uplink Packet Access (HSUPA).

[0041] In another embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A).

[0042] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio access technologies such as IEEE 802.16 (Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

[0043] As an example, Figure 1AThe base station 114b in the example may be a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may use any appropriate RAT to facilitate wireless connectivity in a local area such as a business location, a residence, a vehicle, a campus, or the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may establish a wireless local area network (WLAN) by implementing a radio technology such as IEEE 802.11. In another embodiment, the base station 114b and the WTRUs 102c, 102d may establish a wireless personal area network (WPAN) by implementing a radio technology such as IEEE 802.15. In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may establish a picocell or a femtocell by using a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.). Figure 1A As shown, the base station 114b can be directly connected to the Internet 110. Thus, the base station 114b does not need to access the Internet 110 via the core network 106.

[0044] The RAN 104 may be in communication with a core network 106, which may be any type of network configured to provide voice, data, application and / or voice over Internet Protocol (VoIP) services to one or more WTRUs 102a, 102b, 102c, 102d. For example, the core network 106 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions such as user authentication. Although Figure 1A Although not shown, it will be appreciated that the RAN 104 and / or the core network 106 may be in direct or indirect communication with other RANs, and that these RANs may employ the same RAT as the RAN 104 or different RATs. For example, in addition to being connected to the RAN 104, which may employ E-UTRA radio technology, the core network 106 may also be in communication with another RAN (not shown) employing GSM radio technology.

[0045] The core network 106 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer network devices that use a common communication protocol, and the protocol may be the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another core network connected to one or more RANs, which may use the same RAT as the RAN 104 or a different RAT.

[0046] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities, that is, the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links. Figure 1A The illustrated WTRU 102c may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0047] Figure 1B is a system diagram of an example WTRU 102. Figure 1B As shown, the WTRU 102 may include a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a numeric keypad 126, a display / touchpad 128, a non-removable memory 130, a removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and other peripherals 138. It should be appreciated that the WTRU 102 may include any sub-combination of the foregoing components while remaining consistent with the embodiments.

[0048] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which in turn may be coupled to the transmit / receive element 122. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, however it should be appreciated that the processor 118 and the transceiver 120 may also be integrated into one electronic component or chip.

[0049] The transmit / receive component 122 may be configured to transmit or receive signals to or from a base station (e.g., base station 114a) via the air interface 116. For example, in one embodiment, the transmit / receive component 122 may be an antenna configured to transmit and / or receive RF signals. As an example, in another embodiment, the transmit / receive component 122 may be an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals. In yet another embodiment, the transmit / receive component 122 may be configured to transmit and receive RF and light signals. It should be appreciated that the transmit / receive component 122 may be configured to transmit and / or receive any combination of wireless signals.

[0050] In addition, although Figure 1B 102 as a single component, but the WTRU 102 may include any number of transmit / receive components 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive components 122 (e.g., multiple antennas) for transmitting and receiving radio signals via the air interface 116.

[0051] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As described above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers that allow the WTRU 102 to communicate via multiple RATs, such as UTRA and IEEE 802.11.

[0052] The processor 118 of the WTRU 102 may be coupled to a speaker / microphone 124, a numeric keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit), and may receive user input data from these components. The processor 118 may also output user data to the speaker / microphone 124, the numeric keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store information in any suitable memory such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as, for example, on a server or a home computer (not shown).

[0053] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power for use by the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0054] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) related to the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) via the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information using any suitable positioning method while remaining consistent with an embodiment.

[0055] The processor 118 may also be coupled to other peripheral devices 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripheral devices 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, modules, FM radio units, digital music players, media players, video game console modules, Internet browsers, and more.

[0056] Figure 1C System diagram of the RAN 104 and the core network 106 according to an embodiment. As described above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the core network 106.

[0057] The RAN 104 may include eNode-Bs 140a, 140b, 140c, however it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. Each of the eNode-Bs 140a, 140b, 140c may include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 140a, 140b, 140c may implement MIMO technology. For example, the eNode-B 140a may use multiple antennas to transmit wireless signals to, and receive wireless signals from, the WTRU 102a.

[0058] Each eNodeB 140a, 140b, 140c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, uplink and / or downlink user scheduling, etc. Figure 1C As shown, the eNode-Bs 140a, 140b, 140c may communicate with one another over an X2 interface.

[0059] Figure 1C The illustrated core network 106 may include a mobility management gateway (MME) 142, a serving gateway 144, and a packet data network (PDN) gateway 146. Although each of the foregoing components are described as being part of the core network 106, it should be appreciated that any of these components may be owned and / or operated by an entity other than the core network operator.

[0060] The MME 142 may be connected to each of the eNode-Bs 140a, 140b, 140c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 142 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, performing bearer activation / deactivation processing, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 142 may also provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM or WCDMA.

[0061] The serving gateway 144 may be connected to each of the eNode-Bs 140a, 140b, 140c in the RAN 104 via an S1 interface. The serving gateway 144 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The serving gateway 144 may also perform other functions such as anchoring the user plane during inter-eNode-B handovers, triggering paging processing when downlink data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and the like.

[0062] The serving gateway 144 may also be connected to a PDN gateway 146, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0063] The core network 106 may facilitate communications with other networks. For example, the core network 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks such as the PSTN 108 to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the core network 106 may include or be in communication with an IP gateway, such as an IP Multimedia Subsystem (IMS) server, which may serve as an interface between the core network 106 and the PSTN 108. In addition, the core network 106 may provide the WTRUs 102a, 102b, 102c with access to the networks 112, which may include other wired or wireless networks that are owned and / or operated by other service providers.

[0064] The other networks 112 may further be connected to a wireless local area network (WLAN) 160 based on IEEE 802.11. The WLAN 160 may include an access router 165. The access router 165 may include a gateway function. And the access router 165 may communicate with multiple access points (APs) 170a, 170b. The communication between the access router 165 and the APs 170a, 170b may be carried out via wired Ethernet (IEEE 802.3 standard) or any type of wireless communication protocol. The AP 170a wirelessly communicates with the WTRU 102d over an air interface.

[0065] The total end-to-end delay for a connected wireless transmit / receive unit (WTRU) may be contributed by one or more components. For example, these components may include one or more of the scheduling grant acquisition time, transmission time interval (TTI), processing time, and hybrid automatic repeat request (HARQ) round trip time (RTT).

[0066] Requests, grants, HARQ feedback and / or data may be transmitted in and / or according to the timing of blocks or chunks of fixed or known duration (eg, 1 millisecond), such as subframes. This fixed duration may be referred to as a TTI.

[0067] The processing time may be or may include the time required or used to process (e.g., encode and / or decode) data and / or control signaling or information, such as at or by the WTRU and / or eNode B. The data processing time may be proportional to the transport block (TB) size of the data.

[0068] The HARQ RTT may depend on one or more of: the time relationship between the scheduling grant and the associated transmission (e.g., the scheduled transmission) performed by the sender, the time relationship between the time the sender performs the transmission and the time the receiver transmits HARQ feedback (e.g., an acknowledgement (ACK), a negative acknowledgement (NACK), or a retransmission request); and the time relationship between the time the receiver transmits the HARQ feedback and the time the sender performs the retransmission. As an example, for an uplink (UL) transmission using frequency division duplexing (FDD), the HARQ acknowledgement for a packet received by the eNodeB in subframe n may be reported in subframe n+4. As an example, if the WTRU requires a retransmission, the retransmission may be sent in subframe n+8. Doing so may correspond to a HARQ RTT of 8 milliseconds. For systems using time division duplexing (TDD), the HARQ RTT may depend on the TDD configuration (e.g., the UL / downlink (DL) configuration) and may be at least 8 milliseconds. For LTE DL transmissions, the HARQ scheme may be asynchronous. HARQ feedback may be provided on subframe n+k, where k may be 4 for FDD and at least 4 for TDD, depending on the TDD configuration. Retransmissions may be scheduled at subframe n+k+k1 or later. In this case, k1 may be 4 for FDD and at least 4 for TDD, as an example, depending on the TDD configuration.

[0069] Figure 2 is a table showing an example of a TDD UL / DL configuration. For TDD, multiple TDD UL / DL subframe configurations 210 may be supported, and at least one configuration may be used in the eNodeB. Each TDD UL / DL subframe configuration may include one or more downlink subframes "D", uplink subframes "U", and special subframes "S". An illustrative TDD UL / DL subframe configuration 210 is shown in Table 200, wherein the subframe configuration includes the subframe types listed by the subframe number 230 and the downlink to uplink switch point period 220. A special subframe may include a DL portion, a UL portion, and a guard period between the DL and UL portions, wherein, as an example, the guard period provides the time to switch from DL to UL. A special subframe may be referred to as a hybrid subframe, and these terms are used interchangeably herein.

[0070] Figure 2The subframe may have a duration of 1 millisecond. However, it should be understood that the subframe is not limited to such duration and may be implemented using any time length according to design choices. Here, the uplink-downlink subframe configuration and the uplink-downlink configuration may be used interchangeably. The subframe is used as a non-limiting example of a time unit. Any other time unit may replace the subframe and still be consistent with the present disclosure. Some illustrative time units include symbols, time slots, time slots, and the like.

[0071] Figure 3 300 is a table showing an example of a special subframe configuration. As shown in table 300, each special subframe configuration 310 may use a normal cyclic prefix in a downlink 320 or an extended cyclic prefix in a downlink 360. The downlink portion of a special subframe may be referred to as a downlink pilot time slot (DwPTS), and the uplink portion of a special subframe may be referred to as an uplink pilot time slot (UpPTS). The special subframe may also include a guard period (GP).

[0072] The lengths of these portions of the special subframe may be given in terms of a sampling time (Ts). For example, the sampling time may be (10 milliseconds) / 307,200. However, it should be appreciated that the sampling time is not limited thereto and other time lengths may be used for Ts. In the example shown in table 300, the special subframe configuration 310 may use DwPTS 330 and UpPTS 340 when a normal cyclic prefix is ​​used in the downlink 320, and may use DwPTS 370 and UpPTS 380 when an extended cyclic prefix is ​​used in the downlink 360. Further, the special subframe configuration 310 may be used in conjunction with a normal cyclic prefix in the uplink 345 or an extended cyclic prefix in the uplink 350 when a normal cyclic prefix is ​​used in the downlink 320, and may be used in conjunction with a normal cyclic prefix in the uplink 385 or an extended cyclic prefix in the uplink 390 when an extended cyclic prefix is ​​used in the downlink 360. Example lengths of some of the corresponding portions of the special subframe are shown in table 300. Further, in the example shown in table 300, special subframe configurations 8 and 9 are not used in conjunction with an extended cyclic prefix in the downlink 360, whereas in other examples, special subframe configurations 8 and 9 may be used in conjunction with an extended cyclic prefix in the downlink.

[0073] Figure 44 is a table showing an example of a special subframe configuration in units of symbols. As an example, 14 symbols may be used on each 1 millisecond subframe. For example, the symbol may be an orthogonal frequency division multiplexing (OFDM) or SC-FDMA symbol. As shown in Table 400, for each special subframe configuration 410, the length of the portion in the special subframe may be represented by a sample 420 or a symbol 460. The special subframe configuration may be used in conjunction with a normal cyclic prefix (CP). For example, as shown in Table 400, for each special subframe configuration 410, the DwPTS 430, GP 450, and UpPTS 440 of a particular subframe may be represented by a sample 420. And as shown in Table 400, for each special subframe configuration 410, the length of the DwPTS 470, GP 490, and UpPTS 480 of the special subframe may be represented by a symbol 460. The length of a symbol may be an approximate value.

[0074] Different TDD configurations are provided here. In a TDD system, one or more UL-DL configurations may be used in a cell. The configuration may include a configuration (ConfigCell) that may be cell-specific. The Configcell may be used by some WTRUs for one or more of subframe orientation, scheduling timing and / or HARQ timing (as an example, or all). For some WTRUs, ConfigCell may be used for UL scheduling timing and / or UL HARQ timing. UL scheduling timing may be or may include a relationship between UL grant reception and UL transmission. For example, UL scheduling timing may be or may include an identifier of which DL subframe may be used in which UL subframe to schedule transmission. UL HARQ timing may be or may include at least one of a relationship between UL transmission and HARQ feedback transmission in DL (e.g., on a physical HARQ indicator channel (PHICH)) and / or a relationship between HARQ feedback in DL and retransmission in UL. The term relationship used here may be a designated time relationship. The cell may indicate the ConfigCell in broadcast signaling (e.g., in a system information block (SIB) such as SIB1).

[0075] The configuration may include a configuration (ConfigHARQD) that may be WTRU-specific. ConfigHARQD may be used by some WTRUs for DL ​​HARQ timing. The DL HARQ timing may be or may include a relationship between reception in the DL and HARQ feedback transmission in the UL (e.g., in a physical uplink control channel (PUCCH)). ConfigHARQD may be configured in the WTRU with dedicated signaling.

[0076] The subframe directions in ConfigCell and ConfigHARQD are not necessarily the same. For example, some UL subframes in ConfigCell may be indicated as DL or special subframes in ConfigHARQD. These subframes in different directions in ConfigCell and ConfigHARQD may be referred to as flexible subframes. The configuration may include another configuration (e.g., ConfigDir) that may be used to indicate a subframe direction such as for use with flexible subframes. As an example, ConfigDir may be provided in dynamic signaling in the downlink control information (DCI) format. The ConfigDir may be provided to the WTRU periodically.

[0077] By using three configurations (i.e., ConfigCell, ConfigHARQD, and ConfigDir) together, the direction of some subframes for at least some WTRUs may be changed dynamically (e.g., from UL to DL). The configurations may be provided or transmitted by the eNode-B. The WTRUs may receive and / or use these configurations.

[0078] Reserved subframes may also be provided and / or used. A WTRU may configure subframes that are dedicated for use for at least some specific purposes. Such subframes may be referred to as reserved subframes. For example, subframes in an LTE system may be configured and / or reserved for Multimedia Broadcast Multicast Service (MBMS). These subframes may be referred to as Multicast Broadcast Single Frequency Network (MBSFN) subframes. Figure 2 Subframes such as subframes 3, 4, 7, 8, and / or 9 shown may be configured and / or identified as MBSFN subframes.

[0079] A DL reserved subframe or an MBSFN subframe may include a DL control region and a data region. The DL control region may include a channel indicating the number of symbols in the DL control region (e.g., a physical control format indicator channel (PCFICH)). The DL control region may include one or more DL control channels (e.g., a physical downlink control channel (PDCCH)) that can provide a grant for DL ​​data or UL data. The DL control region may include one or more DL control channels (e.g., PDCCH) that can provide a trigger or request for a sounding reference signal (SRS) or channel state information (CSI) feedback transmission. The DL control region may include one or more HARQ feedback channels (e.g., PHICH) that can be used in the DL to indicate ACK and / or NACK for UL data reception. The control region may include a cell-specific reference signal (CRS). As an example, if there is no data transmission in the data region, the data region will not include a CRS.

[0080] Reserved subframes such as MBSFN subframes may be used for other purposes.MBSFN subframes may be used as a non-limiting example of reserved subframes in the examples herein.

[0081] Some WTRUs may perform blind decoding in reserved subframes. For example, the WTRU may monitor a DL control channel (e.g., PDCCH) in the DL control region of a reserved subframe. The WTRU may monitor a DL control channel (e.g., enhanced PDCCH (EPDCCH)) in the data region of a reserved subframe. As an example, when the WTRU successfully decodes the channel, the WTRU may perform operations in accordance with the DL control channel (e.g., PDCCH or EPDCCH).

[0082] A node (e.g., an eNodeB) or a device (e.g., a WTRU) may have at least one medium access control (MAC) entity. The WTRU or MAC entity may have at least one HARQ entity. For example, there may be (e.g., one) HARQ entity on a MAC entity for a serving cell (e.g., for each serving cell). For the UL (e.g., for the UL direction), there may be (e.g., one) HARQ entity on a MAC entity for (e.g., each) serving cell configured with the UL. A serving cell may be a cell that the WTRU can communicate with and / or a cell that the WTRU can connect to.

[0083] A WTRU, a MAC entity, or a HARQ entity may maintain multiple parallel HARQ processes. A WTRU, a MAC entity, or a HARQ entity may maintain multiple parallel HARQ processes for at least one transmission type or direction, such as UL, DL, or sidelink (SL). In one or more embodiments, a non-limiting number of HARQ processes for a transmission direction may be 8. It should be understood that other numbers, including zero, for transmission directions may be used, and that the number of HARQ processes may be different for different transmission directions.

[0084] By using parallel HARQ processes, transmissions can continue while waiting for HARQ feedback related to successful or unsuccessful reception of previous transmissions.

[0085] Here, WTRU, MAC entity and HARQ entity can be used interchangeably. In one or more embodiments and examples described herein, MAC entity and HARQ entity can be used as non-limiting examples of entities that can maintain, include, contain or manage HARQ processes and / or HARQ processing. Transmission type and transmission direction can also be used interchangeably. In one or more embodiments and examples described herein, UL, DL and SL can be used as non-limiting examples of transmission directions or types. UL, DL and SL can further refer to UL, DL or SL channels established or used for UL, DL or SL transmissions. In one or more embodiments and examples described herein, UL, DL and SL can be interchangeable and still conform to the embodiments provided herein.

[0086] In addition, the HARQ process may be associated with a HARQ process identification or identifier, which may be referred to as a HARQ process ID, for example. The HARQ process may be associated with a HARQ buffer. The buffer (eg, the HARQ buffer) may be or may include a soft buffer.

[0087] The coded bits from one or more repetitions or retransmissions of a TB or data can be soft combined with a soft buffer. For example, in a wireless communication system such as a third generation partnership project (3GPP) LTE cellular communication system, data associated with one or more received messages can be stored in a so-called soft buffer memory, which can be used to store so-called soft information associated with the received bits, wherein the bits can also be referred to as soft bits. The soft information of the received bits can include the most likely value of the bits and / or a measure of their reliability (e.g., an estimate of the received signal energy relative to the noise level). The term "soft information" or "soft bit" generally refers to not making a hard decision on the bit value in the process of demodulation and / or input to the decoder, which can also be referred to as a soft decision. These reliability measures can be used to enhance decoding performance. For example, a decoded received packet and its supporting data (e.g., soft bits) can generally be stored in a soft buffer memory so as to be suitable for combining the data with the retransmitted data in the event that an error occurs in the reception of a packet for a previous transmission or a previous retransmission. The HARQ signal may request a retransmission of data, for example, to enable the retransmitted data to be combined with the originally received packet within the receiver.

[0088] A retransmission of a TB may include the same or different coded bits as an initial (e.g., new) transmission or another retransmission of the TB. A buffer may be or may represent a memory, such as a total amount of memory in bits or bytes. The memory of a buffer may include adjacent and / or non-adjacent memory slices or blocks.

[0089] As an example, by using a shorter TTI, the total end-to-end delay for the connected WTRUs may be reduced and / or latency may be reduced. However, since the HARQ RTT may play a significant role in the end-to-end latency, simply shortening the TTI may not be sufficient. In order to shorten the HARQ RTT, it may be necessary to provide resources for feedback and retransmission earlier (e.g., earlier than the conventional, legacy or longer TTI). In systems that can use separate carrier frequencies for UL and DL (e.g., FDD systems), the HARQ timing is not affected by the availability of resources for feedback and retransmission. For example, UL resources for acknowledging DL receptions are easily provided. In systems that can use the same carrier frequency for both UL and DL (e.g., TDD systems), the ability to shorten the HARQ timing may be affected by the availability of resources for feedback and retransmission. For example, if it is desired to perform HARQ feedback in the UL at n (e.g., 4) times the TTI after the DL data transmission, then in the UL, the carrier may not be available in these n times the TTI. As an example, carrier availability may depend on TTI and uplink-downlink configuration.

[0090] For scheduling and HARQ feedback timing based on the use of one or more new special subframe configurations, the scheduling and HARQ feedback timing can reduce latency in advanced LTE systems. The new special subframe configuration can provide one or more of the following. The new configuration can provide PUCCH transmission and / or physical uplink shared channel (PUSCH) transmission in the UL of the special subframe. And, the new configuration can provide multiple DL and UL parts in the special subframe. In addition, the new configuration can provide DL grants and HARQ feedback in the same subframe. In addition, the new configuration can provide UL grants and UL data transmissions in the same subframe.

[0091] A special subframe may be a mixed UL / DL subframe. A special subframe may be a subframe having at least one UL portion and at least one DL portion. The terms portion, part, and region are used interchangeably herein. A special subframe may be a set of portions and / or time units (e.g., time samples, symbols, time slots, etc.) that may be configured and / or used for UL and / or DL. The configuration may be semi-static or dynamic.

[0092] As an example, a special subframe may be used in conjunction with a transmission based on a short TTI (sTTI) or a time slot. A special subframe (e.g., an additional special subframe) may be used for HARQ feedback. By using a special subframe (e.g., an additional special subframe), the latency of HARQ feedback may be reduced.

[0093] Slot-based transmission can be a way to shorten TTI (eg, starting from subframe-based transmission), however, shortening (eg, or simply shortening) TTI may not be sufficient for reducing latency in a TDD system, as an example.

[0094] Figure 5A 500 is a table showing an example of UL-DL configurations for TTIs based on time slots. As shown in the example in table 500, each UL-DL configuration 510 may include one or more DL or D time slots and one or more UL or U time slots 515. For example, there may be seven (7) configurations numbered 0 to 6 and twenty (20) time slots numbered 0 to 19. Figure 4 As shown, these subframes may have a guard period of size multiple time samples or symbols, thereby not fully utilizing the time slot in the DL and / or UL. Figure 5A For a DL transmission in slot 9 of configuration 4, its feedback will be transmitted at the next occurrence of slot 3 or 4. Therefore, the UL-DL configuration may limit the reduction of latency.

[0095] As an example, a special subframe may be replaced with an UL and / or DL ​​subframe to send HARQ feedback. A special subframe may include at least one DL part and at least one UL part. A special subframe may include at least one GP or gap. GP. Here, GP, gap and gap period are used interchangeably. A gap may have a length of 0 or a length greater than 0. A gap may be represented by a time unit, such as T or a symbol.

[0096] As an example, by replacing special subframes with DL and / or flexible subframes, additional opportunities for UL transmission can be enabled. Examples of replacing special subframes are provided here. Special subframes can be replaced with one or more of the following. Special subframes can be replaced with subframes indicated as UL subframes in ConfigCell (for example, for a certain cell). And, special subframes can be replaced with subframes indicated as DL subframes in ConfigHARQD configured or received by one or more WTRUs. Further, special subframes can be replaced with subframes indicated as DL subframes in ConfigDir that can be configured or received by one or more WTRUs. In addition, special subframes can be replaced with subframes that are regarded as flexible subframes by one or more WTRUs. In another example, special subframes can be replaced with subframes that are indicated or configured as MBSFN subframes in cells such as cells. In addition, special subframes can also be replaced with subframes that can be indicated or configured as MBSFN subframes by means of broadcast or dedicated signaling.

[0097] A special subframe with a first configuration may be replaced with a special subframe with a second configuration. The first configuration may have the same gap as the second configuration, or the first configuration may have a relatively smaller gap or a relatively larger gap than the second configuration. As an example, the second configuration may be provided in a cell-specific broadcast signaling such as an SIB. The first configuration may be provided in dedicated and / or dynamic signaling. The first configuration may have a UL area larger than the second configuration. The first configuration may have a larger DL area than the second configuration. The first configuration may have more DL and / or UL areas than the second configuration.

[0098] For example, the second special subframe configuration, the cell-specific special subframe configuration and / or the special subframe configuration that may be provided in the SIB may be a special subframe configuration with a large gap, e.g. Figure 4 0 or 5 are shown, where the configurations show a gap of 10 symbols and 9 symbols, respectively. As an example, a configuration with a large gap may be indicated in a cell where a large gap is not required. The gap may be used to take into account latency or timing advance. A large gap may be required or used in a large cell. As an example, by indicating or using a configuration with a large gap in a small cell, a WTRU that understands a new subframe (e.g., with a larger UL and / or DL ​​area) may use a special subframe instead of a special subframe configured by a SIB.

[0099] The replacement may be performed in accordance with a configuration, wherein the configuration may be broadcast, may be WTRU-specific and / or may be WTRU-group-specific. An eNodeB or cell may provide a configuration. The configuration may be provided via physical layer signaling, such as provided in a DCI format. The configuration may be provided via higher layer signaling, such as provided via radio resource control (RRC) signaling or broadcast signaling.

[0100] The special subframe may include and / or may start with a DL part. The DL part may include at least a portion of a DL control region. One or more of PCFICH, PHICH, PDCCH, EPDCCH and / or CRS may be included in the DL control region. The UL part may follow the DL part. As an example, there may be a gap between the DL part and the UL part where no transmission is performed. The DL part may include a DL data region. Furthermore, one or more of EPDCCH and / or a physical downlink shared channel (PDSCH) may be included in the DL data region.

[0101] The eNodeB may perform transmission in the DL part. The eNodeB may perform transmission in the DL control region. The eNodeB may transmit at least one of the PCFICH, PHICH, PDCCH, EPDCCH, and / or CRS in the DL part and / or the DL control region. The eNodeB may transmit the EPDCCH and / or PDSCH in the DL data part and / or the DL data region.

[0102] The WTRU may perform reception in the DL part. The WTRU may perform reception in the DL control region. The WTRU may monitor and / or receive at least one of the PCFICH, PHICH, PDCCH, EPDCCH, and / or CRS in the DL part and / or the DL control region. The WTRU may monitor and / or receive the EPDCCH and / or PDSCH in the DL data part and / or the DL data region.

[0103] The UL part may be used to carry UL control information such as PUCCH. The UL part may be used to carry UL data such as PUSCH. The PUCCH and / or PUSCH design may be adapted based on the special subframe configuration, for example based on the UL part of the special subframe.

[0104] The WTRU may perform transmission in the UL part. The WTRU may transmit at least one of the PUCCH and / or the PUSCH in the UL part. The eNodeB may perform reception in the UL part. The eNodeB may receive one or more of the PUCCH and / or the PUSCH in the UL part.

[0105] exist Figure 4 In the example shown for the special subframe configuration, the UL portion may be limited to 1 or 2 symbols. In order to use the special subframe for PUCCH and / or PUSCH, the UL portion may be larger. In the example configuration shown in Table 400, the gap size can be as high as 10 symbols. A large number of symbols can correspond to cells as large as 100 kilometers. However, such a large number of gap symbols will not be used for smaller cells.

[0106] Other special subframe configurations may also be used. For example, the special subframe configuration may include at least one or more of the following: In an exemplary configuration, the special subframe may include a UL portion followed by a DL portion, and as an example, there is no gap between the UL and DL portions.

[0107] Also, in one example configuration, the special subframe may include a gap before the UL portion. The gap before the UL portion may start at the beginning of the special subframe, such as when the special subframe follows a DL subframe or when the special subframe follows a subframe and at least a portion of the subframe may be a DL portion.

[0108] Furthermore, in one example configuration, a special subframe may include a DL portion followed by a gap. The DL portion followed by a gap may be located at the end of a special subframe, such as when the next subframe may be a UL subframe, or when the first portion of the next subframe may be a UL portion.

[0109] A special subframe may include multiple instances of a DL portion, a gap, and a UL portion. For example, a special subframe may have or may include two instances of a DL portion, a gap, and a UL portion. In one example, at least one DL portion may include a control region. In a further example, all DL portions may include a control region.

[0110] Special subframes may be used to create self-contained subframes. In one example, for example, a self-contained subframe may be a subframe in which the WTRU may receive DL grants and / or DL ​​data in the DL portion of the subframe and in which the WTRU may transmit HARQ feedback regarding the DL grants and / or DL ​​data in the UL portion of the subframe. The HARQ feedback may be transmitted on the PUCCH channel in the UL portion of the subframe.

[0111] In a further example, a self-contained subframe may be a subframe in which the WTRU may receive a UL grant in the DL portion of the subframe, and the granted resources may be the UL portion of the subframe, for example. In another example, a self-contained subframe may be a subframe in which the WTRU may receive a UL grant in the DL portion of the subframe and in which the WTRU may perform a UL transmission in the UL portion of the subframe, for example.

[0112] The examples herein also describe a process for configuring a special subframe for a WTRU. As an example, the WTRU may also determine when to use a special subframe for an UL transmission such as a PUCCH or PUSCH transmission. For example, a dynamic indication in a grant (e.g., a DL grant or a UL grant) may indicate the use of a special subframe (e.g., for a PUCCH or PUSCH transmission), and the WTRU may determine which special subframe to use for the UL transmission based on, for example, timing associated with the grant.

[0113] As an example, a special subframe may be configured and / or used for UL transmission of PUCCH, PUSCH and / or HARQ feedback. A set of one or more special subframe configurations may be provided and / or used. As an example, the set may be provided by means of high-layer signaling such as RRC dedicated or broadcast signaling.

[0114] The special subframe configuration may indicate one or more of the following information for the special subframe: the number of DL, UL and / or gap parts in the special subframe; the positioning or location of the DL, UL and / or gap parts within the special subframe; the size of the DL, UL and / or gap parts in the special subframe; an index or other identifier used for or associated with the special subframe configuration; the purpose for which one or more DL parts in the special subframe can be used; and / or the purpose for which one or more UL parts in the special subframe can be used.

[0115] As an example, the usage that the UL and / or DL ​​parts in a specific subframe may be used for may be indicated separately from the special subframe configuration.

[0116] The provided configuration (e.g., ConfigSF) may indicate which subframes may be used as special subframes. The ConfigSF may indicate the purpose for which the indicated subframes (e.g., each indicated subframe or all indicated subframes) may be used, such as UL purpose. The UL purpose may be at least one of HARQ feedback, PUCCH transmission, PUSCH transmission, and / or SRS transmission. As an example, the ConfigSF may indicate the special subframe configuration of one or more (e.g., each or all) subframes indicated by the ConfigSF by its identifier.

[0117] ConfigSF may also indicate which subframes may be used as DL subframes. In one example, ConfigSF may or may also indicate which subframes may be used entirely as DL subframes. Subframes indicated as DL subframes may be UL or special subframes in ConfigCell.

[0118] The ConfigSF may be configured via higher layer signaling, such as RRC signaling, broadcast signaling, or both. The ConfigSF may be configured via physical layer signaling, such as in DCI format. The signaling may be cell-specific, WTRU-specific, and / or WTRU-group-specific. The ConfigSF may be periodically configured and / or updated.

[0119] As an example, the first ConfigSF may be configured via high-level signaling and / or in a semi-static manner. In one example, for example, the first ConfigSF may be a reference ConfigSF that is signaled via high-level signaling and / or in a semi-static manner. The second ConfigSF may be signaled in a dynamic and / or periodic manner. The second ConfigSF may overwrite the first ConfigSF.

[0120] The second ConfigSF may be applicable and / or valid for a length of time (eg, a specific length of time).The WTRU may use at least the ConfigSF to determine which subframes may be used at least occasionally as special subframes.

[0121] As an example, a DL and / or UL grant may indicate that the WTRU uses a special subframe for UL transmission or receives a DL transmission. The special subframe may be indicated in the ConfigSF. The UL transmission may be or may include a HARQ feedback transmission, a PUCCH transmission, and / or a PUSCH transmission in the UL. The DL transmission may be or may include a HARQ feedback transmission in the DL (e.g., on the PHICH), a PDCCH and / or EPDCCH transmission, and / or a PDSCH transmission.

[0122] For example, the DL grant may indicate whether the special subframe may be used for PUCCH transmission and / or HARQ feedback for DL ​​transmission (e.g., in UL and / or PUCCH). For example, the WTRU may transmit PUCCH and / or HARQ feedback in a special subframe based on receiving an indication that the special subframe is used for PUCCH and / or HARQ feedback.

[0123] As an example, a subframe or special subframe for UL transmission, PUCCH transmission and / or for HARQ feedback may be indicated to the WTRU and / or determined by the WTRU in accordance with one or more of the following: the subframe or special subframe may be indicated in the ConfigSF; which subframe may be used as a special subframe in a DL grant; the special subframe may be a subframe indicated as an MBSFN subframe in, for example, a ConfigCell; the special subframe may be the next special subframe that satisfies a criterion or the next subframe that satisfies a criterion indicated in the ConfigSF, wherein the criterion may be the beginning of a special subframe or a portion of a special subframe (e.g., an UL portion) exceeds a threshold amount of time (e.g., in units of subframes, TTIs, symbols, time samples, time slots, etc.) after receiving a DL grant or DL ​​data (e.g., a subframe, a TTI, a symbol, a time sample, a time slot, etc.); the special subframe available for use may start at at least multiple (e.g., n) TTIs after the subframe in which the DL grant or DL ​​data is received; the UL part of the available special subframe may be in a time slot starting at least multiple (e.g., n) TTIs after the start of the time slot in which the DL data is received; the special subframe and the subframe in which the DL grant is received may be the same subframe, such as the current special subframe; as an example, the special subframe may be the current special subframe if the current subframe satisfies the criterion, wherein the criterion may be that the beginning (or a part) of the UL part of the current special subframe exceeds a threshold amount of time (e.g., in units of TTI, symbol, time sample, time slot, etc.) after the time (e.g., TTI, symbol, time sample, time slot, etc.) of receiving the DL grant or DL ​​data; and / or as an example, if the UL part starts at least multiple (e.g., n) TTIs, symbols and / or time samples after the time of receiving the DL grant or DL ​​data, then the UL part of the current special subframe may be used.

[0124] The time unit of TTI may adopt at least one of a subframe, a TTI, a symbol, a time sample and / or a time slot. A DL grant may indicate a special subframe configuration of a special subframe that may be used for PUCCH and / or HARQ feedback.

[0125] Special subframes may be used for PUCCH and / or HARQ feedback transmissions. For example, if the WTRU receives an indication in a DL grant that a special subframe may be used for PUCCH transmission and / or HARQ feedback (e.g., in UL and / or PUCCH), then the WTRU may transmit PUCCH and / or HARQ feedback in a special subframe. The special subframe may be a special subframe described herein. For example, the special subframe may be a subframe indicated in the ConfigSF. The special subframe may be the next special subframe that satisfies the criteria or the next special subframe that satisfies the criteria indicated in the ConfigSF. The criteria may be as described above. As an example, if the current special subframe satisfies the criteria as described herein, then the special subframe may be the current special subframe.

[0126] The replacement and switching used in the examples here can be used interchangeably. In one example, as an example, a special subframe can be replaced with an UL and / or DL ​​subframe to send HARQ feedback. Accordingly, in one example, the UL and / or DL ​​subframe can be switched to a special subframe. In another example, two DL subframes can be switched to a special subframe. In another example, two UL subframes can be switched to a special subframe. In a further example, more than two UL and / or DL ​​subframes can be switched to a special subframe. In one example, one or more subframes switched to a special subframe can be used to send HARQ feedback. Further, the replacement can be performed by means of a broadcasted, WTRU-specific and / or WTRU group-specific configuration. The configuration can be performed by an eNode B or a cell. The configuration can be performed by physical layer signaling such as a DCI format. In addition, the configuration can also be performed by means of high-layer signaling such as RRC signaling or broadcast signaling.

[0127] The WTRU may transmit PUCCH and / or HARQ feedback in the UL portion of a special subframe, for example, in accordance with the special subframe configuration of the subframe. As an example, the location of the PUCCH and / or HARQ feedback in time and / or frequency may depend on the TTI, the location of the DL grant, and / or the location of the DL data transmission.

[0128] For the special subframes that the WTRU may use for transmitting PUCCH and / or HARQ feedback, the WTRU may use the special subframe configuration that it receives in, for example, higher layer signaling, ConfigSF, associated DL grant, and / or other means as described in the examples herein. For example, if the WTRU receives an indication in a DL grant that a special subframe may be used for PUCCH transmission and / or HARQ feedback (e.g., in UL and / or PUCCH), then the WTRU may monitor, attempt to receive, and / or receive DL transmissions in the DL portion of the special subframes that the WTRU may use for transmitting PUCCH and / or HARQ feedback.

[0129] Figure 5B is a diagram showing an example of sending HARQ feedback on a switched special subframe using a configuration supporting sTTI. Figure 5B As shown in the example of , when using the legacy TTI with TDD UL / DL subframe configuration, the WTRU may receive DL data on a DL subframe such as subframe 520. The TTI and subframe may have the same length in time, such as 1 millisecond. In one example, the TDD UL / DL subframe configuration may be TDD UL / DL subframe configuration 2. The WTRU may then send HARQ feedback for subframe 520 on a UL subframe such as subframe 530. Figure 5B In another example shown, a subframe such as subframe 520 may correspond to one legacy TTI and two sTTIs, such as sTTIs 540 and 541. The WTRU may receive DL data in one sTTI (e.g., sTTI 540). The WTRU may then transmit HARQ feedback regarding sTTI 540 on an sTTI corresponding to an UL subframe (e.g., sTTI 560 corresponding to UL subframe 530). As a non-limiting example of the number of sTTIs that may correspond to a subframe and / or a legacy, long, or normal TTI, two sTTIs are used. The WTRU may not send HARQ feedback regarding sTTI 540 on a special subframe such as special subframe 557, for example, because the length of the UL portion 558 of the special subframe 557, which is a legacy special subframe, is not sufficient to support the HARQ feedback transmission.

[0130] To improve latency, the WTRU may switch the DL subframe to a special subframe. Figure 5BIn the example shown, the DL subframe 525 corresponding to the DL sTTI 550 and 555 may be switched to a special subframe 580. The special subframe 580 may include at least a UL portion 585 and a gap portion 583. The WTRU may receive DL data in one sTTI (e.g., sTTI 750). The WTRU may then transmit HARQ feedback regarding the sTTI 570 in the UL portion 585 of the special subframe 580. Figure 5B As can be seen in FIG. 5 , latency can be improved in this manner because the WTRU can send HARQ feedback earlier in the UL portion 585 of the special subframe 580 than in the UL sTTI 560. Figure 5B As further shown in the embodiments, the HARQ feedback can be sent at a UL position that is closest to at least four sTTIs after the corresponding DL data is received, for example, at the closest position that can support HARQ feedback transmission.

[0131] PUSCH transmission may use special subframes. The examples described herein of using special subframes for PUCCH transmission may be applied to the process of using special subframes for PUSCH transmission. For example, the DL grants described herein involving PUCCH transmission may be replaced by UL grants involving PUSCH transmission.

[0132] For example, the UL grant may indicate whether a special subframe can be used for PUSCH transmission. The special subframe may be the next special subframe that satisfies the criteria, or the next special subframe that satisfies the criteria indicated in the ConfigSF. The criteria may have the form described for PUCCH transmission, where the UL grant is replaced by the DL grant.

[0133] As an example, the criterion may be that the beginning of a special subframe or a portion of a special subframe (e.g., the UL portion) exceeds a threshold amount of time (e.g., in units of subframes, TTIs, symbols, time samples, time slots, etc.) after the time (e.g., subframes, TTIs, symbols, time samples, time slots, etc.) of receiving a UL grant.

[0134] The special subframe and the subframe receiving the UL grant (e.g., the current special subframe) may be the same subframe. For example, if the current special subframe satisfies the criteria, then the special subframe may be the current special subframe. The criteria may have the form described for PUCCH transmission, where the UL grant is replaced by a DL grant.

[0135] As an example, the criterion may be that the beginning of the UL portion of the current special subframe (or a portion thereof) exceeds a threshold amount of time (e.g., in units of TTI, symbol, time sample, time slot, etc.) after the time (e.g., TTI, symbol, time sample, time slot, etc.) when the UL grant is received.

[0136] For example, if the WTRU receives an indication in the UL grant that a special subframe may be used for PUSCH transmission, then the WTRU may transmit PUSCH in a special subframe. The special subframe may be a special subframe as described herein. For example, the special subframe may be the next special subframe that satisfies the criteria or the next special subframe indicated in the ConfigSF that satisfies the criteria. The criteria may be as described above. As an example, if the current special subframe satisfies the criteria as described herein, then the special subframe may be the current special subframe.

[0137] The WTRU may transmit a PUSCH in the UL portion of a special subframe, for example, in accordance with a special subframe configuration of the subframe. For example, the location of the PUSCH in time and / or frequency may depend on the TTI and / or UL grant location. As an example, if the WTRU receives an indication in an UL grant that a special subframe may be used for PUSCH transmission, the WTRU may monitor, attempt to receive and / or receive DL transmissions in the DL portion of the special subframe in which it may transmit PUSCH. When a special subframe is used for PUSCH transmission, for example, HARQ feedback in the DL from the eNodeB may be provided in the DL subframe or DL ​​portion of the special subframe in accordance with a certain configuration or rule. The UL grant (or other information in the DCI format and including the UL grant) may include or identify the configuration or rule to be used. For example, if a NACK is received or an ACK is not received, the WTRU's retransmission may be performed in accordance with the configuration or rule. The configuration or rule may be indicated in or together with the UL grant.

[0138] The PUCCH transmission may use a special subframe UL symbol. For example, the PUCCH transmission may use a special subframe UL symbol and / or time sampling that may correspond to an UpPTS symbol of the special subframe or an UpPTS portion of the special subframe. As an example, a special subframe may include or end with a plurality of symbols (e.g., NS symbols), wherein the plurality of symbols may be UL symbols or UpPTS symbols. As an example, Figure 4As shown in the UpPTS, the number of symbols (which can be described as a length in symbols) can be 1 or 2. One or more NS symbols can be used for (e.g., typically used for or reserved for) SRS transmission. SRS transmission can be triggered by an eNode B. The SRS transmission can be used for UL channel measurement, such as occasional UL channel measurement. As an example, the resources available in the NS symbol are not used at least sometimes. The available resources in the NS symbol can be used to create additional PUCCH transmission opportunities in TDD special subframes, such as short or shortened PUCCH (sPUCCH) transmission opportunities. The sPUCCH transmission opportunity in the special subframe configuration can be independent of the special subframe configuration. For example, the sPUCCH transmission opportunity can be used for HARQ feedback to reduce RTT delay.

[0139] As an example, sPUCCH can be used when there are fewer symbols available for UL transmission than the legacy PUCCH. In one example, sPUCCH can be used when UL sTTI is used to transmit UL control information such as HARQ feedback. In another example, the UL symbols available in a special subframe may be limited to a certain number, such as 1 or 2 symbols, which may be too short for the legacy PUCCH design. Therefore, sPUCCH can be used instead.

[0140] Figure 6 is a diagram showing examples of HARQ feedback delay with and without sPUCCH transmission in the UpPTS of a special subframe. As shown in the example of diagram 600, TDD UL / DL configuration 2 can be used with legacy PUCCH transmission 610 and can be used with sPUCCH transmission in UpPTS 660. sPUCCH transmissions may be allowed in special subframes (e.g., UpPTS of special subframes). HARQ feedback may be transmitted using sPUCCH. In this example, for at least some instances of PDSCH reception (e.g., instances where the HARQ feedback delay is > 4 subframes or TTIs), the delay between DL reception and HARQ feedback transmission may be reduced by 1 subframe or TTI. Figure 6 In the example shown, k can be the time distance between the PDSCH and the corresponding HARQ feedback in the number of subframes. By using sPUCCH in special subframes (such as UpPTS), the average value k can be reduced from 6.25 subframes or TTIs to 5.5 subframes or TTIs.

[0141] exist Figure 6In the example shown, the WTRU may receive PDSCH 620 in DL subframe 0 and PDSCH 630 in special subframe 1 in accordance with TDD UL / DL configuration 2 used with legacy PUCCH transmission 610. The WTRU may then transmit HARQ feedback, such as ACK or NACK, for the PDSCH in the next available UL subframe 4 subframes after receiving the PDSCH, which may be UL subframe 7, for example. As a result, the WTRU may transmit ACK or NACK 625 for PDSCH 620 and ACK or NACK 635 for PDSCH 630 in UL subframe 7.

[0142] Furthermore, in accordance with TDD UL / DL configuration 2 used with sPUCCH transmission in UpPTS 660, the WTRU may receive PDSCH 670 in DL subframe 0 and PDSCH 680 in special subframe 1. The WTRU may then transmit HARQ feedback, such as ACK or NACK, in the next available special subframe or UL subframe after receiving the PDSCH and 4 subframes later, which may be special subframe 6. Thus, the WTRU may transmit ACK or NACK 675 for PDSCH 670 and ACK or NACK 685 for PDSCH 680 in special subframe 6. As a result, the feedback delay may be reduced by 1 subframe by using sPUCCH transmission in UpPTS 660 instead of the legacy PUCCH transmission 610.

[0143] For sPUCCH transmissions performed on (or at least on) SRS resources, the WTRU may be configured with a set of parameters. In one example, the parameters may be or may include a set of parameters defined, configured and / or used for SRS. In another example, the parameters may be or may include a subset of a set of parameters defined, configured and / or used for SRS. The parameters may include information related to the resource location or information used to determine location information. The location information may include frequency resources, bandwidth and / or resource blocks (RBs). SRS may include periodic and / or non-periodic SRS. SRS may include trigger type 0 and / or type 1 SRS. The parameter set may be or may include one or more parameters that are independent of SRS (type 0 and / or type 1) parameters. For example, the group of parameters may be or may include all parameters that are independent of SRS (type 0 and / or type 1) parameters.

[0144] Multiple parameter sets may be configured and / or used. Different WTRUs or groups of WTRUs may be configured with separate parameters and / or may use separate parameters. As an example, the number of parameter sets (e.g., three) and the number of parameter sets (e.g., three) configured for SRS triggering type 1 and / or DCI format 4 may be the same. Which parameter set the WTRU may use may be configured or indicated in a semi-static manner (e.g., by higher layer signaling) or in a dynamic manner (e.g., by physical layer signaling).

[0145] The availability of special subframe resources for sPUCCH transmission may be configured, indicated and / or permitted by high-layer signaling or physical layer signaling (e.g., by means of a DL control channel or DCI format). The availability of special subframe resources may take effect immediately in the same subframe as the indication or in a later special subframe, for example, in the next special subframe available for sPUCCH or the next special subframe. Special subframe resources may be or may include UL symbols or resources, UpPTS symbols or resources and / or SRS symbols or resources.

[0146] The availability and / or usage of special subframe resources for sPUCCH transmission may depend on the frame configuration (e.g., TDD UL / DL configuration). For example, special subframe resources may be provided for and / or may be used for sPUCCH transmissions associated with all PDSCH reception events or a subset thereof. Special subframe resources may be provided for and / or may be used for sPUCCH transmissions associated with all PDSCH events or a subset thereof for which the corresponding HARQ feedback may experience a long delay (e.g., greater than 4 or 5 subframes). The delay may depend on the frame configuration. The WTRU may determine the availability or unavailability of resources (e.g., special subframe resources) for sPUCCH transmission without any additional signaling. For example, for Figure 6 In the UL / DL configuration 2 shown, the availability and / or usage of special subframes may be applied to (e.g., only to) HARQ feedback relative to the reception of PDSCH 640, 690 in subframe 4 and the reception of PDSCH 650, 669 in subframe 9. In the case of using the legacy PUCCH, the reception of PDSCH 640, 650 in subframes 4 and 9 may encounter the longest HARQ feedback delay, such as the longest delay of HARQ feedback 645 and HARQ feedback 655, respectively. In the case of using sPUCCH, the reception of PDSCH 690, 691 in subframes 4 and 9 encounters a shorter HARQ feedback delay, such as a shorter delay of HARQ feedback 695 and HARQ feedback 696, respectively, such as 1 subframe or 1 millisecond.

[0147] The SRS may be configured to span RBs that are multiples of several RBs in frequency (e.g., 4 RBs). In addition, the SRS may be configured to span RBs that are any multiples of several RBs in frequency. The sPUCCH may also span (e.g., any) multiples of several RBs that may be allowed by the SRS configuration (e.g., 4 RBs). For example, if the availability of a single UL symbol is provided in a specified configuration, the SRS bandwidth may be configured to be as large as the bandwidth required for the sPUCCH transmission. As an example, the transmitted sPUCCH block may perform rate matching or repetition over several RBs in order to achieve higher coding gain.

[0148] sPUCCH transmissions may be transmitted concurrently with SRS transmissions. SRS mapping may be done on a subset of subcarriers (e.g., every second subcarrier). Unused resources may be used to carry sPUCCH. As an example, since SRS may be used to perform channel estimation associated with PUCCH demodulation, sPUCCH transmissions may not be accompanied by (e.g., any) UL DMRS. As an example, if SRS and sPUCCH are transmitted concurrently, some of the SRS power may be transferred to sPUCCH. This transfer may improve performance.

[0149] The WTRU may use MBSFN subframes as special subframes. In one example, for example, at least some WTRUs may use MBSFN subframes as special subframes in a cell. When using DL subframes as special subframes, backward compatibility with legacy WTRUs may be allowed by configuring DL subframes that may be used as special subframes as MBSFN subframes. The WTRU may receive a configuration or indication of which MBSFN subframes may be used as special subframes.

[0150] In the examples described herein, the term MBSFN subframe may be substituted for the term special subframe, and vice versa, and still be consistent with the examples provided herein.

[0151] For some WTRUs (e.g., legacy WTRUs), they do not expect DL grants, DL data, and / or CRS in MBSFN subframes. As an example, MBSFN subframes may be used to perform UL transmissions in areas of subframes that are not used for DL ​​control. As an example, MBSFN subframes may be used for UL transmissions without affecting legacy WTRUs.

[0152] Some WTRUs (e.g., LTE R10 WTRUs) may blindly decode DL control channels in MBSFN subframes, but may not expect CRS in the data region of the MBSFN subframes (e.g., if the WTRU does not receive a grant in that subframe). As an example, MBSFN subframes may be used for UL transmissions in situations that affect WTRUs such as these.

[0153] The WTRU may monitor and / or receive a DL control channel in an MBSFN subframe. The DL control channel may indicate whether the MBSFN subframe may be used as a DL subframe or a special subframe.

[0154] The WTRU may receive an indication in a UL grant and / or a DL grant as to whether an upcoming (or current) MBSFN subframe may be used as a special subframe and / or for UL transmission. If the WTRU determines that an upcoming (or current) MBSFN subframe may be used as a special subframe and / or may be used for UL transmission, the WTRU may determine which MBSFN subframe may perform the process according to the criteria. If the WTRU determines that an upcoming (or current) MBSFN subframe may be used as a special subframe and / or may be used for UL transmission, the WTRU may perform UL transmission in the subframe.

[0155] As an example, a DL grant may indicate whether an MBSFN subframe may be used as a special subframe. A DL grant may be used to indicate whether an MBSFN subframe may be used for PUCCH transmission and / or HARQ feedback for DL ​​transmission (e.g., on UL and / or PUCCH). As an example, if the WTRU determines that an MBSFN subframe may be used for PUCCH transmission and / or for HARQ feedback based on an indication in a DL grant, the WTRU may transmit the PUCCH and / or HARQ feedback in the determined subframe.

[0156] The following illustrative process may be used in accordance with a design that uses an MBSFN subframe as a special subframe. For example, which MBSFN subframe is to be used may be indicated in a DL grant. Also, the DL grant and / or other configuration may indicate a special subframe configuration for the MBSFN subframe. In another example, the MBSFN subframe may be the current or next MBSFN subframe that satisfies a criterion. The criterion may be the beginning of an MBSFN subframe or a portion (e.g., UL portion) of an MBSFN subframe (e.g., in accordance with a special subframe configuration of an MBSFN subframe) exceeds a threshold amount of time after the time of receiving a DL grant or DL ​​data. As an example, the threshold amount of time may be expressed in terms of a subframe, TTI, symbol, time sample, time slot, etc. Also, as an example, the time of receiving a DL grant or DL ​​data may be expressed in terms of a subframe, TTI, symbol, time sample, time slot, etc.

[0157] In another example, the MBSFN subframe that can be used may start at least a plurality of TTIs, such as n TTIs, after the subframe in which the DL grant or DL ​​data is received. In an additional example, the UL portion of the MBSFN subframe that can be used (e.g., in accordance with a special subframe configuration of the MBSFN subframe) may be in a time slot that starts after the start of the time slot in which the DL data is received and at least a plurality of (e.g., n) TTIs have passed.

[0158] Further, as an example, if the current MBSFN subframe satisfies the criteria, then the MBSFN subframe may be the current special subframe. The criteria may be that the beginning (or a portion) of the UL portion of the current MBSFN subframe (e.g., in accordance with the special subframe configuration of the MBSFN subframe) exceeds a threshold amount of time after the time when the DL grant or DL ​​data is received. As an example, the threshold amount of time may be expressed in terms of subframes, TTIs, symbols, time samples, time slots, etc. And as an example, the time when the DL grant or DL ​​data is received may be expressed in terms of subframes, TTIs, symbols, time samples, time slots, etc. In another embodiment, for example, if the UL portion of the current special subframe begins when at least a plurality (e.g., n) of TTIs, symbols, and / or time samples have passed after the time when the DL grant or DL ​​data is received, then the UL portion may be used.

[0159] As an example, the examples described herein of PUCCH transmissions performed in subframes configured as MBSFN subframes may be applied to PUSCH transmissions performed in subframes configured as MBSFN subframes. In these examples, DL grants may be replaced with UL grants without loss of functionality.

[0160] UL channel design examples for special subframes and variable-sized UL transmission regions are provided herein. In particular, PUCCH and PUSCH design examples are provided herein in accordance with UL region size and with respect to variable-sized UL regions to be transmitted. PUCCH and / or PUSCH may be designed in accordance with the time available for channel transmission. The channel design may include resource allocation in time and / or frequency.

[0161] For example, the PUCCH and / or PUSCH in a special subframe may be designed according to at least one of the number of time samples, symbols, physical resource blocks (PRBs), and / or resource elements (REs) in (or available in) the UL portion of the special subframe. In addition, the PUCCH and / or PUSCH in another time span may be designed according to at least one of the number of time samples, symbols, physical resource blocks (PRBs), and / or resource elements (REs) available for (or available in) the UL portion of the other time span.

[0162] The PUCCH and / or PUSCH in a special subframe may be designed according to at least one of the number of time samples, symbols, PRBs and / or REs available for UL transmission in the special subframe. In addition, the PUCCH and / or PUSCH in another time span may be designed according to at least one of the number of time samples, symbols, PRBs and / or REs available for UL transmission in the another time span.

[0163] The PUCCH and / or PUSCH in a special subframe may be designed according to the frequency position of the PRB in the special subframe and / or at least one of the REs available for UL transmission. In addition, the PUCCH and / or PUSCH in another time span may be designed according to the frequency position of the PRB in the another time span and / or at least one of the REs available for UL transmission.

[0164] The design parameters of PUCCH may include one or more of the following characteristics of PUCCH: frequency location; TTI; number of REs; number of PRBs; use of frequency hopping; and / or such as the starting symbol within the subframe, time sampling or other time units. The design parameters of PUSCH may include one or more of the following characteristics of PUSCH: TTI; use of frequency hopping; such as the starting symbol within the subframe, time sampling or other time units; location of UL reference signals (RS) (e.g., demodulation reference signals (DM-RS)); and / or transport block size (TBS).

[0165] In a special subframe, one or more design parameters for the PUCCH and / or PUSCH may be based on or in accordance with the configuration of the special subframe, e.g., the configuration of the special subframe in which the PUCCH and / or PUSCH may be or is expected to be transmitted. The WTRU may determine one or more design parameters for the PUCCH and / or PUSCH in a special subframe based on or in accordance with the special subframe configuration.

[0166] The special subframe configuration may include at least one of the following: the size of the DL part in terms of time samples, symbols and / or other time units; the size of the UL part in terms of time samples, symbols and / or other time units; and / or the size of the gap in terms of time samples, symbols and / or other time units.

[0167] The special subframe configuration may include PUCCH resource allocation in the special subframe. For example, the special subframe configuration may include PUCCH resource allocation in one or more UL parts of the special subframe.

[0168] In one example, a subframe may have a number of symbols S1 that can be used for UL transmission (e.g., PUCCH and / or PUSCH transmission). The subframe may be configured and / or determined to occupy or be allocated C1 subcarriers. Another subframe may have a number of symbols S2 that can be used for UL transmission (e.g., for PUCCH and / or PUSCH transmission). The subframe may be configured and / or determined to occupy or be allocated C2 subcarriers. If S1 < S2, then C1 may be greater than C2. Other time units such as time sampling or time slots may be replaced by the symbols in the examples described herein. More symbols for UL transmission may correspond to fewer subcarriers or REs for UL transmission.

[0169] The WTRU may be configured to have a PUCCH allocation based on the number of symbols allocated for the PUCCH. This process may be a basic PUCCH allocation method. The WTRU may determine a PUCCH allocation method for allocating multiple (e.g., different numbers of) symbols to the PUCCH in a subframe based on the basic PUCCH allocation method. The basic allocation method may use S1 symbols and C1 carriers. The WTRU may determine an allocation method for another subframe that uses S2 symbols. The allocation method for other subframes may include the number of subcarriers, e.g., C2, and / or the allocation location in the frequency. The allocation method for other subframes may be determined in accordance with at least one of S1, S2, C1, and / or the frequency location in the basic allocation method.

[0170] In the embodiments and examples described herein, the PUSCH may be replaced by the PUCCH and vice versa, and still be consistent with the examples provided herein. It should be understood that any combination of the disclosed features / components may be used in one or more embodiments and examples.

[0171] Fig. 7A is an illustration showing an example of transmitting HARQ feedback on the PUCCH in the UL portion of the determined resources of the determined special subframe having the determined special subframe configuration. As Fig. 7A shown in the example of, the WTRU may receive a time division duplex (TDD) uplink (UL) / downlink (DL) subframe configuration 710. Further, the WTRU may receive a DL grant 715 having an indication regarding the use of a special subframe for PUCCH transmission. Then, the WTRU may dynamically determine which subframe to switch to the special subframe, and may switch the subframe to the special subframe 720. Further, the WTRU may determine a special subframe configuration 725 for the determined special subframe. And, the WTRU may determine the resources 730 of the special subframe determined to be used for the PUCCH.

[0172] The WTRU may then determine PUCCH resources and PUCCH design parameters for the PUCCH 735. Furthermore, the WTRU may transmit HARQ feedback 740 on the PUCCH in the UL portion of the determined resources of the determined special subframe with the determined special subframe configuration using the determined PUCCH resources and PUCCH design parameters.

[0173] In one example, the WTRU may also receive DL data in a DL subframe. The WTRU may then transmit HARQ feedback in a determined special subframe after the DL subframe and after at least four sTTIs.

[0174] In the examples provided herein, LTE guard bands may be used. In particular, the guard bands may be configured, determined, and / or used for UL resources and / or DL ​​resources. The guard bands may be configured, determined, and / or used for performing HARQ feedback transmissions in UL and / or DL. The guard bands may be configured, determined, and / or used for UL resources and / or DL ​​resources for performing HARQ feedback transmissions.

[0175] Here, the terms HARQ feedback, HARQ-ACK, HARQ indication and ACK / NACK indication are used interchangeably. In addition, guard band, secondary carrier, extended carrier and second frequency band are also used interchangeably.

[0176] Figure 7B 700 is a diagram showing an example of a guard band PRB configuration for HARQ feedback. As shown in the example in diagram 700, PRBs 760 and 770 in guard band A and PRBs 780 and 790 in guard band B may be configured and / or used. The guard band PRB configuration and / or use of the guard band PRBs are not limited to HARQ feedback transmission.

[0177] In the examples provided herein, a guard band PRB configuration may be provided and / or used. The PRBs in the guard band may be referred to as G-PRBs, while the PRBs in the system bandwidth may be referred to as S-PRBs. The terms PRB, PRB pairing, and RB may be used interchangeably and are still consistent with the embodiments provided herein.

[0178] A G-PRB set may be close to or adjacent to an S-PRB set (e.g., in frequency or PRB). In one example, the number of S-PRBs may be determined based on an indication from a broadcast channel (e.g., a master information block (MIB) or SIB), and the number of G-PRBs may be determined based on at least one of: an indication from higher layer signaling; one or more system parameters (e.g., physical cell ID, system bandwidth, etc.); and / or carrier frequency.

[0179] One or more G-PRBs may be used for a certain transmission scheme (or mode) configuration. For example, if the WTRU is configured with a short TTI transmission scheme (or mode), then the G-PRBs may be used. The high-layer signaling for the short TTI transmission scheme may include all or part of the configuration information about the G-PRBs.

[0180] As an example, the WTRU may determine the G-PRB configuration based on detection of a physical cell ID (PCI) from a synchronization channel and / or one or more system parameters obtained from a broadcast channel.

[0181] One or more G-PRBs may be located immediately following the lowest S-PRB index, immediately following the highest S-PRB index, or immediately following both the lowest and highest S-PRB indexes.

[0182] In the examples provided herein, the TDD subframe configuration may be provided to and / or used for the guard band PRB. In one example, the TDD configuration (e.g., UL / DL subframe configuration) for the S-PRB and for one or more G-PRBs may be independently configured. In another example, the TDD configuration for one or more G-PRBs may be determined based on the TDD configuration for the S-PRB.

[0183] Figure 8 800 is a diagram showing an example of a TDD configuration for a G-PRB based on a TDD configuration for an S-PRB. In the example shown in diagram 800, a first TDD configuration 810 may be used for an S-PRB and a second TDD configuration 860 may be used for one or more G-PRBs, or vice versa. For example, the first TDD configuration 810 may be TDD UL / DL configuration 0 in accordance with an indication received by the WTRU. The first and second TDD configurations may be indicated with an offset. For example, the first TDD configuration may be indicated from a broadcast channel (e.g., MIB) transmitted in one or more S-PRBs, and the second TDD configuration may be indicated as an offset from the first TDD configuration.

[0184] The second TDD configuration 860 may be determined based on the first TDD configuration 810. One or more of the following examples may be applied. For a DL subframe or a UL subframe, based on the first TDD configuration, a subframe in the opposite direction may be used in the second TDD configuration. For example, if subframe n is a DL subframe in the first TDD configuration, then the subframe n is a UL subframe in the second TDD configuration. Figure 8 As shown in the example in , the DL subframes 811, 816 in the first TDD configuration 810 can be used as UL subframes 861, 866 in the second TDD configuration 860. And, the UL subframes 813, 814, 815, 818, 819, 820 in the first TDD configuration 810 can be used as DL subframes 863, 864, 865, 868, 869, 860 in the second TDD configuration 860. In another example, the special subframe for subframe n in the first TDD configuration can be replaced by a UL subframe in the second TDD configuration 860. In an additional example, the special subframe for subframe n in the first TDD configuration can be used as a special subframe in the second TDD configuration. For example, the special subframes 812, 817 in the first TDD configuration 810 can be used as special subframes 862, 867 in the second TDD configuration 860. Furthermore, one or more special subframe attributes may be different for the first TDD configuration and the second TDD configuration (e.g., DwPTS, UpPTS, and / or Gap). The UL portion of the special subframe in the second TDD configuration may have a greater number of uplink symbols (e.g., SC-FDMA symbols) than the UL portion of the special subframe in the first TDD configuration.

[0185] Fig. 9 900 is a diagram showing an example of a timing offset between an S-PRB and a G-PRB. In the example shown in diagram 900, the timing of a TDD subframe for one or more G-PRBs 960 may be determined, configured, or indicated based on the timing of a TDD subframe for one or more S-PRBs 910.

[0186] As an example, by using a timing offset (Toffset), the timing of one or more G-PRBs 960 (e.g., the timing of the subframes for the G-PRBs) may be determined or configured based on the timing of one or more S-PRBs 910 (e.g., the timing of the subframes for the S-PRBs). The timing offset may be determined or configured by one or more of the following examples. Toffset may be determined based on the processing time of the short TTI. The processing time of the short TTI may be indicated in at least one of a broadcast channel, a higher layer signaling, and a WTRU capability indication. Toffset may be determined based on the short TTI length. If the short TTI length is Nshort[ms], then Toffset may be Nshort x Noffset[ms]. In one example, Toffset may be configured by higher layer signaling. In a further example, Toffset may be greater than the subframe length, such as 1 millisecond. In another example, the WTRU may blindly detect Toffset. For example, a synchronization signal may be sent in one or more G-PRBs at a predetermined time position. The WTRU may use the synchronization signal transmitted in the G-PRB, and may optionally use the synchronization signal transmitted in the S-PRB, to determine Toffset.

[0187] In the example provided here, HARQ feedback may use guard band PRBs.PUSCH, PDSCH, or both may be transmitted in S-PRBs, and associated HARQ feedback may be transmitted in G-PRBs.

[0188] One or more G-PRBs may be used for PUCCH transmission, where, as an example, the PUCCH transmission may carry or include HARQ feedback associated with PDSCH transmission in one or more S-PRBs. Further, one or more G-PRBs may be used for EPDCCH transmission, where, as an example, the EPDCCH transmission may carry or include HARQ feedback associated with PUSCH transmission in one or more S-PRBs. Here, the terms EPDCCH, machine type communication (MTC) PDCCH (M-PDCCH), short PDCCH (S-PDCCH), and narrowband PDCCH (NB-PDCCH) are used interchangeably. HARQ feedback associated with one or more UL transmissions may be transmitted via E-PDCCH. For example, what is transmitted may be a DCI with a group radio network temporary identifier (RNTI), where the DCI may carry HARQ feedback associated with one or more UL transmissions. One or more G-PRBs may be used for PDSCH transmissions, which may carry or include HARQ feedback associated with PUSCH transmissions in S-PRBs, for example.

[0189] Fig.10 is a diagram showing an example of HARQ feedback resource determination. Based on the availability of HARQ feedback resources in one or more S-PRBs, a subframe subset in one or more G-PRBs may be used for HARQ feedback. As an example, for a PDSCH (or PUSCH) transmission, if the associated HARQ feedback resources are available in one or more S-PRBs within a certain time window, then the HARQ feedback corresponding to the PDSCH transmission may be transmitted in one or more S-PRBs. Otherwise, the associated HARQ feedback may be transmitted in one or more G-PRBs.

[0190] The specific time window may be predefined. For example, if one or more S-PRBs are used to transmit the PDSCH in subframe n, and HARQ feedback resources are available in one or more S-PRBs on subframe n+k, then the associated HARQ feedback may be transmitted in one or more S-PRBs. If the HARQ feedback resources are not available in one or more S-PRBs on subframe n+k, then the associated HARQ feedback may be transmitted in one or more G-PRBs. Here, k may be a positive integer. In addition, the specific time window may be determined based on the TTI length, for example, based on the short TTI length. In the example of diagram 1000, k may be 1. As shown in diagram 1000, the WTRU may receive and / or use a TDD UL / DL subframe configuration for S-PRB 1010. As an example, in accordance with an indication received by the WTRU, the configuration may be TDD UL / DL configuration 0. Further, the WTRU may transmit HARQ feedback associated with the S-PRB in one or more G-PRBs 1060. The WTRU may receive the PDSCH on an S-PRB in a DL subframe, such as DL subframe 1015. The S-PRB one subframe after the DL subframe 1015 may be a special subframe 1020 that does not have sufficient UL resources to carry HARQ feedback. The WTRU may transmit the HARQ feedback associated with the S-PRB DL subframe 1015 in a G-PRB UL subframe 1050. In another example, as an example, since a DL subframe 1040 is available 1 subframe after the UL subframe 1030, the WTRU may transmit the PUSCH in the S-PRB UL subframe 1030 and may receive the HARQ feedback associated with the transmission in the S-PRB DL subframe 1040. As an example, since a subframe one subframe after DL subframe 1040 may be a special subframe 1070 that does not have sufficient UL resources to carry HARQ feedback, the WTRU may receive PDSCH in the S-PRB DL subframe 1040 and may transmit HARQ feedback associated with the DL transmission in the G-PRB subframe 1080.

[0191] In another example, the HARQ feedback resource may be indicated (implicitly or explicitly) in an associated downlink control channel that may be used for PDSCH or PUSCH scheduling. For example, two types of HARQ feedback resources may be used, predefined or configured, and one of the HARQ feedback resource types may be indicated in an associated downlink control channel.

[0192] For example, the first type of HARQ feedback resource may be a HARQ feedback resource that may be located in one or more S-PRBs or transmitted in the one or more S-PRBs, while the second type of HARQ feedback resource may be a HARQ feedback resource that may be located in one or more G-PRBs or transmitted through the one or more G-PRBs. The type of HARQ feedback resource may be defined based on one or more of the following: the RNTI used for the downlink control channel, the (enhanced) control channel element ((E)CCE) index used, and / or the PRB index used. The type of HARQ feedback resource may also be indicated in the DCI.

[0193] In one example, sTTI transmission in one or more S-PRBs may use a subframe subset, and based on the subframe subset used for sTTI transmission in one or more S-PRBs, a corresponding subframe subset in one or more G-PRBs that can be used for HARQ feedback (e.g., for HARQ feedback transmission) can be determined.

[0194] The subframe subsets used for sTTI transmissions in one or more S-PRBs may be known to the eNodeB and / or the WTRU. For example, the subframe subsets used for sTTI may be predetermined based on the TDD subframe configuration. The subframe subsets used for sTTI may be indicated in a broadcast channel. The subframe subsets used for sTTI may be configured in a WTRU-specific manner with the aid of higher layer signaling.

[0195] Examples of using HARQ buffers and process processing are described herein, including DL HARQ processing and UL HARQ processing. As an example, HARQ processing can be applied in the DL. The HARQ entity can direct HARQ information received on a shared channel (e.g., DL shared channel (DL-SCH)) and associated TBs to corresponding HARQ processes such as on a WTRU in the DL. For a TTI or subframe, at least one TB may be expected. For example, if the physical layer is not configured to perform spatial multiplexing (e.g., DL spatial multiplexing), then one TB may be expected. If the physical layer is configured to perform spatial multiplexing (e.g., DL spatial multiplexing), then one or two TBs may be expected. The TB may be received on the PDSCH.

[0196] The HARQ process associated with a TTI and / or a transmission (e.g., a DL transmission) may be indicated (e.g., by an eNodeB) and / or received (e.g., by a WTRU) in a received resource grant (e.g., a received DL grant). The terms grant, resource grant, and assignment may be used interchangeably herein.

[0197] HARQ processing may be applied in the UL. As an example, a HARQ entity may identify one or more HARQ processes for which a targeted UL transmission should occur on a TTI (e.g., a TTI in which a UL grant is indicated). The HARQ entity may route one or more of the following information to one or more appropriate HARQ processes: received HARQ feedback (e.g., ACK / NACK information), a modulation and coding scheme (MCS), and / or one or more resources, such as one or more time / frequency resources used for transmission. At least some of this information may be received from the physical layer. At least some of this information may be received in a UL grant, such as in a UL grant associated with a UL transmission. HARQ feedback may be applicable to synchronous UL HARQ. For some UL HARQ (e.g., asynchronous UL HARQ), HARQ feedback is not applicable.

[0198] The HARQ process associated with the TTI and / or for which a corresponding transmission may or should occur may be indicated (eg, by an eNodeB) and / or received (eg, by a WTRU) in the received resource grant. The received resource grant may be a received UL grant.

[0199] One or more HARQ processes may be associated with a specified TTI. For example, when the physical layer is not configured for spatial multiplexing (e.g., UL spatial multiplexing), one HARQ process may be associated with a specified TTI. When the physical layer is configured for spatial multiplexing (e.g., UL spatial multiplexing), two HARQ processes may be associated with a specified TTI. TBs may be transmitted on the PUSCH.

[0200] The WTRU may be configured to use multiple HARQ processes in the UL and / or DL, for example, 8 HARQ processes in the UL and DL. The number of HARQ processes may be used to determine the total amount of memory (e.g., the total amount of soft buffer memory) that the WTRU may need to maintain to support transmissions and retransmissions. Based on the maximum TB size and the number of HARQ processes, the WTRU may determine the maximum amount of memory that it may need to maintain to support maintenance in the UL and / or DL ​​to support transmissions and retransmissions in the UL and / or DL. The maximum TB size may depend on the TTI length, the allowed MCS, and / or other parameters.

[0201] For example, a system (e.g., an LTE-A system) may use a fixed or known (e.g., 1 millisecond) TTI length (e.g., a first TTI length). The WTRU may have a memory size that may be associated with multiple HARQ processes (e.g., 8 HARQ processes) in the UL and / or DL. The memory size for each HARQ process may correspond to the maximum TB size for the fixed or known TTI length.

[0202] As an example, another TTI such as an sTTI (e.g., a second TTI) may be available to or used by the WTRU to reduce latency in the system. The second TTI may be shorter than the first TTI and may be referred to as a short TTI (sTTI). The first TTI may be used at least some of the time (e.g., some or all of the time). And the second TTI may also be used at least some of the time (e.g., some or all of the time). The first and second TTIs may sometimes (e.g., some or all of the time) be used simultaneously or in adjacent time intervals. For example, the first TTI may be used in a first subframe and the second TTI may be used in a next adjacent subframe.

[0203] Examples of handling HARQ processes and HARQ buffers for multiple TTI lengths are provided herein. In one example, a separate HARQ process and HARQ buffer may be used for each separate TTI in the first and second TTI lengths.

[0204] Fig.11 11 is a diagram showing an example of separate HARQ processes and HARQ buffers for two TTI lengths. As an example, the two TTI lengths may be TTI 1 and TTI 2. As shown in the example of 1100, separate HARQ processes and HARQ buffers may be used for TTI 1 and TTI 2. For example, HARQ process buffer 1110 may be used for TTI 1 and HARQ process buffer 1160 may be used for TTI 2. However, the separate processes and buffers may result in an increased amount of storage required in the WTRU without reducing the number of HARQ processes. For Fig.11 For the example in FIG. 1 , eight HARQ processes 1110 for TTI 1 plus eight HARQ processes 1160 for TTI 2 would require memory. This arrangement may waste memory, for example, when one of the TTIs (e.g., TTI 1 or TTI 2) is used more frequently than another TTI (e.g., TTI 2 or TTI 1) during a period of time. In this example, eight HARQ processes are used for TTI 1 and eight HARQ processes are used for TTI 2. Any number of HARQ processes may be used for each of TTI 1 and TTI 2 and still be consistent with the examples described herein.

[0205] In one example, for example, by reducing the number of processes, the memory size can be maintained. For example, by reducing the number of HARQ processes, the memory size can be maintained.

[0206] Fig.1212 is a diagram showing another example of separate HARQ processes and HARQ buffers for two TTI lengths. As shown in the example of diagram 1200, HARQ process buffer 1210 may be used for TTI 1, such as when TTI 1 may be used without TTI 2. When both TTI 1 and TTI 2 are used, HARQ process buffer 1260 may be used. TTI 1 may be a normal TTI. TTI 2 may be an sTTI.

[0207] exist Fig.12 In the example shown, the second TTI (e.g., TTI 2) may be an sTTI and may be half the length of the first TTI (e.g., TTI 1). For the HARQ process buffer 1260, the number of processes for the first TTI may be reduced to 6 and the number of processes for the second TTI may be configured to 4, thereby using a memory equivalent in number to the memory required for the 8 processes of the first, longer TTI of the HARQ process buffer 1210. However, as an example, if the number of processes for the first or second TTI is reduced from 8 processes in 1210 and 1110 for TTI 1 and 1160 for TTI 2, new transmission delays may be incurred due to retransmissions because less buffer is available for new data while old data is being retransmitted. Also, if the number of HARQ processes or buffers per TTI length is configured in a fixed or semi-static manner, inefficiencies may result, as an example, because sometimes one TTI is used more than another TTI.

[0208] Thus, further alternative means for sharing memory for HARQ processing in multiple TTIs are disclosed in the examples provided herein. In particular, in one or more examples, one or more of the memory, buffers, or processes for HARQ processing can be shared or divided between two or more TTI lengths. As an example, the sharing or division process can be configured and / or indicated in a dynamic manner. It should be understood that, herein, TTI and TTI length can be used interchangeably.

[0209] The first TTI may be or may correspond to one or more of the following: a regular TTI, a normal TTI, a nominal TTI, a long TTI, a longest TTI available for or configured to be used by the WTRU, a subframe (SF), 1 millisecond, a group of symbols (e.g., 14 symbols), etc. Herein, the first TTI may be referred to as nTTI. The nTTI may be referred to as a normal TTI.

[0210] The second TTI may be or may correspond to one or more of the following: a short TTI, a reduced length TTI, a TTI shorter than nTTI, a portion of a subframe, less than a subframe, less than 1 millisecond, a time slot, a group of symbols (e.g., multiple symbols, such as 1, 2, 3, 4, and 7 symbols), etc. Here, the second TTI may be referred to as sTTI.

[0211] The HARQ process or buffer for nTTI may be used for multiple sTTIs. The number of sTTIs for which the HARQ process or buffer may be used may depend on the sTTI length and / or the nTTI length. For example, the number of sTTIs for which the HARQ process or buffer may be used may be a function of the TTI length, such as a configurable sTTI length. As an example, the WTRU may determine the number of sTTIs for which the HARQ process or buffer may be used based at least on the sTTI length (e.g., the longest sTTI length that may be configured). The eNodeB may configure the WTRU to use one or more sTTIs having one or more lengths, and the WTRU may determine the number of sTTIs for which the HARQ process or buffer may be used based at least on the sTTI length that the WTRU may be configured to use.

[0212] As an example, the number of sTTIs that can use the HARQ process or buffer can be configured by the eNodeB via higher layer signaling, such as RRC signaling. The WTRU can receive the configuration. The WTRU can determine the number of sTTIs that can use the HARQ process or buffer based at least on the configuration.

[0213] For example, the length of sTTI may be half of nTTI. As an example, when the length of sTTI is half or less than half of the length of nTTI, one HARQ process or buffer for one nTTI may be used for two sTTIs. As an example, when the length of sTTI is less than or equal to one quarter of nTTI, for example, when the length of sTTI is 3 symbols and the length of nTTI is 14 symbols, one HARQ process or buffer for one nTTI may be used for four sTTIs.

[0214] Fig.13is a diagram showing an example for linking or sharing HARQ processes, HARQ buffers, or both before two TTI lengths. In the examples described herein, the two TTI lengths may be nTTI and sTTI. In one or more embodiments and examples described herein, HARQ processes and HARQ buffers may be interchangeable and still be consistent with the examples provided herein. Further, the phrases HARQ buffer and HARQ process buffer may be used interchangeably herein. Here, the term process / buffer may be used to represent a process, a buffer, or both. A process / buffer may be a HARQ process / buffer.

[0215] In the example shown in diagram 1300, one nTTI HARQ buffer may be divided and / or used for two sTTI HARQ buffers. The number of nTTI HARQ buffers 1310 may be one or more. In example 1300, one or more nTTI HARQ buffers 1310 may be divided and / or used for one or more sTTI HARQ buffers 1360. For example, nTTI HARQ buffer 2 1320 may be divided and / or used for sTTI HARQ buffers 2a 1330 and 2b 1340. Further, nTTI HARQ buffer 4 1350 may be divided and / or used for sTTI HARQ buffers 4a 1380 and 4b 1370.

[0216] The nTTI HARQ buffer can be used for either nTTI data or sTTI data. In one example, the nTTI HARQ buffer is not used for both nTTI data and sTTI data. Fig.13 In the example shown, nTTI HARQ buffers 2 and 4 may be used for sTTI data, while other nTTI HARQ buffers may be used for nTTI data. The HARQ buffers may represent memory available for use by the HARQ process. The HARQ buffers may or may not be located at fixed locations in the memory. The HARQ buffers may include contiguous memory locations, discontinuous memory locations, or both.

[0217] Fig.141400 is a diagram showing an example timeline for use with multiple TTI lengths. In the example shown in diagram 1400, the period in which the transmission is performed is a subframe that can correspond to 1 millisecond. A subframe is a non-limiting example of a transmission period. nTTI can be the same duration as the period (e.g., subframe). sTTI may be shorter than nTTI. For example, the length of sTTI may be half of nTTI or less than half of nTTI. In example 1400, sTTI may be used in subframes 2, 4, and 8, while nTTI may be used in every other subframe. One sTTI may be used in subframes 2 and 8. Two sTTIs may be used in subframe 4.

[0218] for Fig.13 and Fig.14 For the example shown, the WTRU may use HARQ processes, buffers, or both for data (e.g., for transmitting or receiving data) in the following manner in a subframe: nTTI in subframe #0 (SF0) may use process / buffer 0, nTTI in SF1 may use process / buffer 1, sTTI in SF2 may use the first half of process / buffer 2 (e.g., process / buffer 2a), nTTI in SF3 may use process / buffer 3, the first sTTI in SF4 may use the second half of process / buffer 2 (e.g., process / buffer 2b), the second sTTI in SF4 may use the first half of process / buffer 4 (e.g., process / buffer 4a), nTTI in SF5 may use process / buffer 5, nTTI in SF6 may use process / buffer 6, nTTI in SF7 may use process / buffer 7, and sTTI in SF8 may use the second half of process / buffer 4 (e.g., process / buffer 4b). Thus, sTTI data may be transmitted / received using the next available sTTI buffer in the multiple HARQ buffers. In this way, the buffer can be used for nTTI, sTTI or both as needed.If there are N HARQ buffers (eg N=8), then transmissions / retransmissions in later subframes can reuse these N HARQ buffers.

[0219] Examples for linking sTTI and nTTI HARQ processes / buffers are provided herein. For example, one or more HARQ processes and / or buffers may be implemented with at least one of linking, sharing, or overlapping. As an example, a first HARQ process and / or buffer may be linked, shared, or overlapped with a second HARQ process and / or buffer. In the embodiments and examples described herein, the terms linking, overlapping, and sharing are interchangeable and still consistent with the examples provided herein.

[0220] Fig.13 An example is shown in which nTTI HARQ process / buffer k can be linked, shared, or overlapped with sTTI HARQ process / buffer ka and sTTI HARQ process / buffer kb, where k = 0, 1, ... 7. As an example, nTTI HARQ process / buffer 0 can be linked, shared, or overlapped with sTTI HARQ process / buffer 0a and sTTI HARQ process / buffer 0b. Further, nTTI HARQ process / buffer 2 can be linked, shared, or overlapped with sTTI HARQ process / buffer 2a and sTTI HARQ process / buffer 2b. And, nTTI HARQ process / buffer 4 can be linked, shared, or overlapped with sTTI HARQ process / buffer 4a and sTTI HARQ process / buffer 4b. Such linking, sharing, or overlapping can be applied to all nTTI and sTTI HARQ processes / buffers or a subset thereof.

[0221] Fig.15 1500 is a diagram showing another example of HARQ processes, buffers, or both that may be linked, shared, or overlapped. As shown in diagram 1500, a first set (e.g., a basic set) of HARQ processes / buffers may be linked, overlapped, or shared with a second set of HARQ processes / buffers. In one example, the first set may be all or some of the HARQ processes / buffers 1510, and the second set may be all or some of the HARQ processes / buffers 1560. For example, nTTI HARQ processes and / or buffer 2 may be linked, shared, or overlapped with sTTI HARQ processes and / or buffers 4 and 5. Similarly, nTTI HARQ processes and / or buffer 4 may be linked, shared, or overlapped with sTTI HARQ processes and / or buffers 8 and 9.

[0222] Fig.16 is a diagram showing another example for linking, sharing, or overlapping HARQ processes, buffers, or both. Fig.17 is a diagram showing another example for linking, sharing or overlapping HARQ processes, buffers, or both. In particular, Fig.16 and 17More examples of HARQ processes, buffers, or both that can be linked, shared, or overlapped are shown. Some processes can be linked to other processes. Some processes will not be linked to other processes. Some processes can be linked to other processes that may be linked to other processes. In one example, the processes numbered 0-7 in diagram 1600 can be nTTI processes, while other processes (e.g., processes 8-15) can be sTTI processes. In one example, HARQ process 1610 can be an nTTI process, and HARQ process 1660 can be an sTTI process. In diagram 1700, processes numbered 0-5 can be nTTI processes, and other processes (e.g., processes 0a-0d, 1a-1b, 1aa-1bb, and 8-11) can be sTTI processes. The corresponding buffer can be used and divided / subdivided according to the assigned corresponding process (e.g., whether the process is an nTTI process, an sTTI process, or an sTTI subprocess).

[0223] The WTRU may receive a configuration (e.g., a configuration message, signal, or information) from a base station (e.g., an eNodeB) indicating that at least one HARQ process / buffer may be linked, shared, or overlapped with another HARQ process / buffer. The configuration may indicate that a first HARQ process / buffer may be linked, shared, or overlapped with a second HARQ process / buffer or one or more other HARQ processes / buffers. For example, the configuration may indicate that HARQ process i may be linked with HARQ processes j and k, where i, j, and k may be integers.

[0224] The first HARQ process / buffer may be an nTTI HARQ process / buffer, and the second or one or more other HARQ processes / buffers may be (one or more) sTTI HARQ processes / (one or more) buffers. The second or other HARQ processes / buffers may be the same, different, independent, dependent and / or associated with each other.

[0225] When a first HARQ process is linked to a second HARQ process, a buffer available for use by a TB of the first HARQ process will be available for use by a TB of the second HARQ process. In one example, the buffer may be a soft buffer. For example, if HARQ process A is linked to HARQ processes B and C, then using HARQ processes B and / or C (e.g., indicating the use of HARQ processes B and / or C) may indicate that data associated with HARQ process A may be overwritten or discarded. Data associated with HARQ processes B and / or C may use at least a portion of a buffer previously used for HARQ process A. Subsequent use of HARQ process A may be considered as new data or an indication of new data for HARQ process A. If HARQ process A is used, for example, indicating the use of HARQ process A, then it may be indicated that data associated with HARQ processes B and / or C may be overwritten or discarded. Data A associated with a subsequent HARQ process A may use one or more buffers previously used for HARQ processes B and / or C. Furthermore, subsequent use of HARQ processes B and / or C may be considered as new data or an indication of new data for one or more corresponding HARQ processes.

[0226] Examples for determining the use of HARQ processes / buffers are provided herein. For example, the eNodeB may manage, configure and / or indicate via signaling to the WTRU at least one HARQ process / buffer that may be used by the WTRU for (eg, each) transmission.

[0227] The WTRU may receive an indication of which HARQ process to use to transmit or receive data. As an example, the indication may be dynamically received in a control channel (e.g., a DL control channel), where, for example, the channel may be a PDCCH, EPDCCH, S-PDCCH (which may be referred to as sPDCCH), M-PDCCH (which may be referred to as mPDCCH), NB-PDCCH, etc. The indication may be received in control information carried by the control channel (e.g., DL control information (DCI)). The control channel, the control information, or both may provide a grant of data to be transmitted or received (for example, which may indicate resources), and the grant may include an indication of which HARQ process to use to transmit or receive data. The indication of which HARQ process to use may be or may include a HARQ process ID or number.

[0228] The transmission may be performed in UL or SL. The reception may be performed in DL or SL. The data may be used to represent at least one of a TB, a plurality of TBs, a DL channel, or a UL channel. As an example, the DL channel may be a PDSCH or a short PDSCH (sPDSCH). The UL channel may be a PUSCH or a short PUSCH (sPUSCH). Channel reception and / or reception on a channel may include combining repetitions of a channel / repetitions on a channel, for example when operation is performed using coverage enhancement. As an example, when operation is performed using coverage enhancement, channel transmission / transmission on a channel may include transmitting channel repetitions / transmitting repetitions on a channel.

[0229] In one example, the WTRU may receive an indication (e.g., via a message, signal, control channel, or control information, such as a DCI format) to use a HARQ process or HARQ buffer, wherein the HARQ process or HARQ buffer may have at least one of a linked, shared, or overlapping relationship with another HARQ process or buffer. The indication may be received in a control channel and / or control information (e.g., DCI) including a grant regarding a resource, such as a UL or DL ​​resource. The eNodeB may provide the indication. As an example, the WTRU may receive the indication from the eNodeB. The WTRU may use the indication for processing and configuration.

[0230] The eNodeB may provide and / or the WTRU may receive at least one of the following indications (e.g., in a DL control channel or DCI containing a grant (e.g., a DL or UL grant): an indication of a process / buffer to be used; an indication of a process / buffer to be used for data; an indication of a process / buffer for data associated with a grant (e.g., a DL grant or a UL grant) (e.g., DL data or UL data); an indication of a process / buffer for data associated with a grant that can be linked, shared, or overlapped with another process / buffer; an indication of a basic process / buffer (e.g., an nTTI process / buffer); an indication of a process / buffer that can be linked, shared, or overlapped with a basic process / buffer (e.g., an sTTI process / buffer); an indication of a sub-buffer or sub-process to be used for transmission and / or reception such as an sTTI; an indication of the TTI length of the data; an indication that the TTI for the data can be an sTTI or an nTTI; and an indication of whether the data for the process / buffer is new data or retransmitted data (e.g., a new data indicator (NDI) can be switched to indicate new data). The NDI may be provided in the grant. The NDI may be provided in or together with an indication of the HARQ process to be used.

[0231] As an example, the WTRU may determine one or more HARQ processes and / or buffers that may be linked, shared, or overlapped with one or more other HARQ processes and / or buffers based at least on semi-static and / or dynamic signaling and / or configuration received from an eNodeB.

[0232] Hereinafter, a HARQ process associated with a first TTI length may be referred to as nHARQ, and a HARQ process associated with a second TTI length may be referred to as sHARQ. The first TTI length may be longer than the second TTI length. The soft buffer size for nHARQ may be larger than the soft buffer size for sHARQ. One or more sHARQs may be linked, shared, or overlapped with nHARQ. One or more sHARQ sets may be linked with nHARQ (e.g., a single nHARQ). The sHARQ set linked with nHARQ may be dynamically indicated from / through DCI. One or more sHARQ sets may be predefined, configured, or determined based on a TTI length (e.g., a TTI length associated with sHARQ). One or more sHARQ sets may be determined based on WTRU capabilities.

[0233] A WTRU may receive DCI associated with a DL, UL, or SL transmission, and the DCI may include a HARQ process ID or number and HARQ linking information. For example, a WTRU may receive DCI related to an UL transmission having a first TTI length, and the DCI may indicate an nHARQ ID or number (e.g., a HARQ process ID or number for the first TTI length) and one or more sHARQ IDs or numbers that may be linked. It should be understood that the terms process ID or process number may be used interchangeably herein.

[0234] The first type of HARQ process number (eg, nHARQ number) may be used for transmission and retransmission of data (eg, stored or to be stored in a soft buffer).

[0235] A second type of HARQ process number (e.g., an sHARQ number) may be used to flush the buffer. For example, one or more soft buffers associated with the second type of HARQ process number may be flushed and may be used for the first type of HARQ process number (e.g., an nHARQ number). The second type of HARQ process number may be indicated in a bit field of the DCI. The number of second type HARQ processes may be determined (e.g., by an eNodeB and / or a WTRU) based on the first TTI length and / or the second TTI length. For example, if the first TTI length is twice the second TTI length, two second type HARQ processes may be indicated from the DCI.

[0236] The presence of a second type of HARQ process number (e.g., an sHARQ number) may be determined based on one or more of: a DCI type, an RNTI type, a higher layer configuration, a TTI length associated with the HARQ process, and a transmission scheme associated with the HARQ process.

[0237] DCI types may be used here. For example, a first DCI type may include only a first type of HARQ process number, and a second DCI type may include a first type of HARQ process number and one or more second type of HARQ process numbers. The WTRU may monitor the first DCI type and the second DCI type in a WTRU-specific search space.

[0238] RNTI types may be used here. For example, a DCI with a first RNTI type (e.g., a cell RNTI (C-RNTI)) may include only a first type of HARQ process number. A DCI with a second RNTI type (e.g., a HARQ-C-RNTI (HC-RNTI)) may include one or more first and second types of HARQ process numbers.

[0239] The WTRU may monitor, receive, decode and / or attempt to decode a first DCI type in a first subframe subset, and may monitor, receive, decode and / or attempt to decode a second DCI type in a second subframe subset. The first subframe subset and the second subframe subset may be non-overlapping. Alternatively, the first subframe subset and the second subframe subset may partially or completely overlap.

[0240] The subframe subset for the first DCI type and / or the second DCI type may be determined based on a subframe number and / or a system frame number (SFN).

[0241] A first DCI type may be monitored / received in the first PDCCH candidate subset, and a second DCI type may be monitored / received in the second PDCCH candidate subset. The first PDCCH candidate subset and the second PDCCH candidate subset may be non-overlapping.

[0242] Fig.18 18 is a diagram illustrating an example of using dynamic indications to link or share HARQ processes, buffers, or both. In the example shown in diagram 1800, if nHARQ 0 is indicated, the WTRU may receive a first type of DCI that does not indicate any second HARQ process number, if nHARQ1 is indicated, the WTRU may receive a second type of DCI that indicates a second HARQ process number (e.g., sHARQ0 and sHARQ2), and so on. Fig.18As shown, each of nHARQ1, nHARQ3, nHARQ4 and nHARQ6 can be linked to two sHARQs indicated in a second type of DCI. The second type of DCI can be received in sTTI or nTTI.

[0243] The linking, sharing and / or overlapping of HARQ processes and / or buffers may depend on one or more sTTI lengths to be used. Based on the one or more sTTI lengths to be used, for example, based on the longest sTTI length that can be used, the WTRU may determine the linking, sharing and / or overlapping of HARQ processes and / or buffers. As an example, the one or more sTTI lengths that can be used may be configured by the eNode B. The one or more sTTI lengths or lengths that can be used may be WTRU specific.

[0244] An example of DL operation with a HARQ process is provided herein. A DL process (eg, a MAC process) associated with a HARQ process and / or a HARQ buffer may be used and / or modified in accordance with one or more embodiments described herein.

[0245] An example process for DL ​​data reception at a WTRU may be referred to as example process 1, and the process may include one or more of the following operations. It should be appreciated that one or more of the following operations may be performed in a serial, parallel, or overlapping manner, and that unless expressly stated, no order of performance of the operations, portions of the operations, or performance of the operations in an exclusive manner without intervening or intervening operations should be inferred.

[0246] Example process 1 may include one or more of the following operations. The WTRU may receive a DCI indicating a DL grant associated with an identified HARQ process A. There may be a TB here (e.g., spatial diversity is not used). The WTRU may determine whether the data is a new transmission or a retransmission. For example, the WTRU may determine whether the NDI has been switched compared to the value of the previously received transmission corresponding to the TB. As an example, if the WTRU determines that the NDI has been switched, then the WTRU may determine that the data is a new transmission. As an example, if the WTRU determines that the data is a new transmission, then the WTRU may attempt to decode the received data. As an example, if the WTRU does not successfully decode the data, then the WTRU may replace the data for the TB in the soft buffer with the data it attempts to decode. As an example, if the WTRU determines that the data is a retransmission, then the WTRU may combine the received data with the data about the TB currently in the buffer and may attempt to decode the combined data. For example, the WTRU may send an ACK or a NACK based on whether it successfully decodes the data. The WTRU may send an ACK or a NACK to the eNodeB.

[0247] At the end of example procedure 1, there may be data for HARQ process A TB in the soft buffer. As an example, the WTRU may keep the data in the buffer until the WTRU receives an indication to use the buffer for new data, as described for example procedure 1. Alternatively, once it is determined that it has successfully decoded the data for HARQ process A, the WTRU may reuse the memory associated with the buffer for the same or another HARQ process.

[0248] By modifying the example process 1, it can be used for linked HARQ processes. The linked HARQ processes may be as described herein.

[0249] Furthermore, the determination of whether the data of the TB associated with the HARQ process is likely to be new data may be based at least on whether the transmission received since the previous transmission corresponding to the TB was received is for the linked HARQ process. It should be understood that one or more of the following operations may be performed in a serial, parallel or overlapping manner, and unless explicitly stated, it should not be inferred that the operations, the order of execution of some parts of the operations, or the execution of the operations are performed in an exclusive manner without the occurrence of intervening or intermediate operations.

[0250] For example, the WTRU may perform one or more of the following operations: The WTRU may receive a DCI indicating a DL grant for HARQ process A, where the HARQ process A may correspond to a TB.

[0251] The WTRU may determine that a HARQ process linked to HARQ process A, such as HARQ process B or C, has received a transmission since the previously received transmission corresponding to the TB.

[0252] The WTRU may consider or determine that the NDI has been switched and / or may consider or determine that the transmission is a new transmission. The WTRU may make this determination based at least on its determination that the HARQ process linked to HARQ process A has received a transmission since a previously received transmission corresponding to the TB. The WTRU makes this determination independently and the determination is made regardless of whether the NDI has actually been switched since a previously received transmission corresponding to the TB.

[0253] When a linked HARQ process receives new data, the WTRU may release at least some or all buffer memory associated with the HARQ process. The release of memory may be used for other purposes, such as for another HARQ process that may be a linked HARQ process. For example, when the WTRU receives new data for a HARQ process linked to HARQ process A (e.g., HARQ process B or C), the WTRU may release at least some or all buffer memory associated with HARQ process A. Additionally or alternatively, for example, when the WTRU receives new data for a HARQ process linked to HARQ process B and / or C (e.g., HARQ process A), the WTRU may release at least some or all buffer memory associated with HARQ process B and / or C. Accordingly, the WTRU may use at least a portion of the same buffer memory for the linked HARQ processes.

[0254] In the examples and embodiments described herein, one TB is used for non-limiting illustrative purposes. The embodiments and examples described can be extended to multiple TBs and still be consistent with the examples provided herein.

[0255] An example of UL operation with HARQ processes is provided herein. UL processes (eg, MAC processes) associated with HARQ processes and / or HARQ buffers may be used, modified, or both processes may be performed simultaneously.

[0256] An example procedure, referred to as example procedure 2, by which a WTRU may perform an UL data transmission may include one or more of the following operations. The following one or more operations may be performed in a serial, parallel, or overlapping manner, and unless expressly stated, no order of performance of the operations, portions of the operations, or performance of the operations in an exclusive manner without intervening or intervening operations should be inferred. As an example, the WTRU may perform one or more of the following operations.

[0257] The WTRU may receive a DCI indicating an UL grant with an identified HARQ process A. As an example, when asynchronous HARQ is used, the HARQ process may be identified. For example, when synchronous HARQ is used, such as when the WTRU may use or is configured to use sTTI at least some of the time, the HARQ process may be identified. If the WTRU may be configured to use sTTI at least some of the time, the HARQ process may be identified. For example, the HARQ process may be identified for sTTI transmissions. When the WTRU may be configured to use sTTI at least some of the time, the HARQ process may be identified for nTTI transmissions.

[0258] For data (e.g., data transmitted by or for an identified HARQ process), the WTRU may determine whether the data is a new transmission or a retransmission. For example, the WTRU may determine whether the NDI (e.g., in associated HARQ information) is toggled compared to a value in a previous transmission of the HARQ process or for the transmission. As an example, if the WTRU determines that the NDI is toggled, then it may determine that the data is a new transmission. Additionally or alternatively, if the HARQ buffer of the identified HARQ process is empty, then the WTRU may determine that the data is a new transmission.

[0259] As an example, if the WTRU determines that the data is for a new transmission, the WTRU may perform one or more of the following operations. The WTRU may obtain a TB (e.g., a MAC protocol data unit (PDU)), which may be, as an example, a new TB. Further, the WTRU may transmit the TB to the identified HARQ process. And, the WTRU may instruct the identified HARQ process to trigger a new transmission.

[0260] As an example, if the WTRU determines that the data is not for a new transmission, the WTRU may perform one or more of the following operations. The WTRU may deliver an UL grant and / or HARQ information (e.g., a redundancy version) to the identified HARQ process. Further, the WTRU may instruct the identified HARQ process to generate a retransmission. As an example, the retransmission may be an adaptive or non-adaptive retransmission.

[0261] The WTRU or HARQ process may transmit or retransmit the TB of the HARQ process. For example, the TB of the HARQ process may be a TB in the HARQ buffer of the identified HARQ process.

[0262] When the number of retransmissions reaches or exceeds a configurable threshold, the WTRU may refresh the HARQ buffer of the identified HARQ process. In one example, in this manner, when the number of retransmissions reaches or exceeds a configurable threshold, the WTRU may clear the HARQ buffer of the identified HARQ process.

[0263] The process described herein may be modified to be used for linked HARQ processes. For example, a determination as to whether data that may be transmitted by or for a first HARQ process is new data may be based at least on whether a transmission (e.g., a new data transmission) has been requested or performed for a second HARQ process (e.g., a linked HARQ process) since a previous transmission by the first HARQ process.

[0264] The WTRU may flush at least part or all of the HARQ buffers of a first HARQ process when a transmission (e.g., a new data transmission) is requested or performed for a second HARQ process (e.g., a linked HARQ process). For example, for a first HARQ process (e.g., HARQ process A) that is linked to two HARQ processes (e.g., HARQ processes B and C), the WTRU may flush the buffers of HARQ process B and the buffers of HARQ process C when a data transmission (e.g., a new data transmission) is requested for HARQ process A. The WTRU may flush at least part or all of the HARQ process buffers of HARQ process A when a data transmission (e.g., a new data transmission) may be requested for either HARQ process B or HARQ process C.

[0265] See also Fig.17As an example, upon requesting data transmission (e.g., a new data transmission) for at least one of the HARQ processes 0a, 0b, 0c, or 0d, the WTRU may flush the HARQ buffers of the HARQ process 0. Upon requesting data transmission (e.g., a new data transmission) for the HARQ process 0, the WTRU may flush at least one or all of the HARQ buffers for the HARQ processes 0a, 0b, 0c, and 0d. The transmission request may be made with the aid of a DCI and / or a UL grant. The DCI may include a UL grant.

[0266] In another example, the WTRU may perform or be configured to perform one or more of the following operations. The WTRU may receive a DCI indicating an UL grant with an identified HARQ process A. As an example, the WTRU may determine whether data transmitted by or for the identified HARQ process is a new transmission or a retransmission. As an example, if a data transmission (e.g., a new data transmission) has been requested for a linked HARQ buffer or a linked HARQ process since the last transmission of the identified HARQ process, the WTRU may determine that the data is a new transmission. As an example, if the WTRU determines that the NDI has been switched, the WTRU may determine that the data is a new transmission. As an example, if a data transmission (e.g., a new data transmission) has been requested for a linked HARQ buffer or a linked HARQ process since the last transmission of the identified HARQ process, the WTRU may determine that the NDI has been switched. The WTRU may perform transmission or retransmission processing for the identified HARQ process based on the determination of a new transmission or a retransmission.

[0267] In the embodiments and examples described herein, the terms refresh, empty, release, reuse and rewrite are interchangeable and still consistent with the examples provided herein. If the terms refresh, empty and / or release a buffer or memory are used, it means that a memory, such as a memory associated with a buffer, can be used, reused and / or rewritten.

[0268] A buffer or memory may be associated with a first process and may be used or reused by a second process. The rewrite process may be performed by data (e.g., bits) for or associated with the second process, such as data for a buffer associated with the second process. As an example, the second process may be the same as the first process for the indicated new data. And as an example, the second process may be a different process from the first process for the indicated new data. The second process may be a process linked to the first process. The process may be a HARQ process. The buffer may be a HARQ buffer. The memory may be a soft buffer memory. The memory may be a memory for DL-SCH data, PDSCH, UL shared channel (UL-SCH) data, and / or PUSCH. The buffer associated with the second process may be linked, shared, and / or overlapped with the buffer associated with the first process.

[0269] The WTRU may assume or may be configured to assume that it does not need to reserve or maintain memory for data associated with the second HARQ process, for example when the WTRU uses or may be instructed to use a first HARQ process linked to the second HARQ process. In one example, the memory is a separate or additional memory.

[0270] When the WTRU may be using or may be instructed to use a first HARQ process that may be linked to a second HARQ process, the WTRU may be configured to assume that it does not need to reserve or maintain memory (e.g., separate or additional memory) for data associated with the second HARQ process until the WTRU receives an indication (e.g., an explicit indication) regarding a data transmission or reception (e.g., a new data transmission or reception) related to the second HARQ process. The indication may be from the eNodeB.

[0271] Fig.191900 is a diagram showing an example of HARQ buffer sharing processing implemented by different HARQ processes. In one example, the WTRU may allocate a TB to a HARQ process for UL transmission. In the example shown in diagram 1900, the WTRU may link a first HARQ process and a second HARQ process, wherein the first HARQ process is associated with a first HARQ buffer and a first TTI length, and the second HARQ process is associated with the first HARQ buffer and a second TTI length 1910. The WTRU may transmit a first TB using the linked first HARQ process and the first HARQ buffer 1920. And, the WTRU may receive a UL grant 1930. The WTRU may then determine that the received UL grant is for a new transmission for the linked second HARQ process 1940. Further, the WTRU may release the first HARQ buffer based on determining that the received UL grant is for a new transmission for the linked second HARQ process 1950. In addition, the WTRU may generate a second TB for the new transmission 1960. In another example, the WTRU may allocate a second TB for the new transmission. In another example, the WTRU may either acquire the second TB for the new transmission, assemble the second TB for the new transmission, or perform both simultaneously.In an additional example, the WTRU may receive the second TB for the new transmission.

[0272] Additionally, the WTRU may store the second TB in the first HARQ buffer 1970. Furthermore, the WTRU may transmit the second TB 1980 using the linked second HARQ process and the first HARQ buffer.

[0273] The second TB may overwrite or replace some or all of the first TB in the first HARQ buffer. For example, if the first TB is no longer needed, the first HARQ buffer may be used for the second TB. As an example, if the eNodeB successfully receives the first TB for UL transmission or the WTRU successfully receives the first TB for DL ​​reception, the first TB is no longer needed. In one example, the first TTI length may be an nTTI length and the second TTI length may be an sTTI length, or vice versa.

[0274] In one example, the first TB and the second TB may be MAC PDUs. Furthermore, the first TB may contain data associated with a first TTI, and the second TB may contain data associated with a second TTI.

[0275] Another example of a DL transmission that may use HARQ buffer sharing processing implemented by different HARQ processes. For example, the WTRU may allocate a TB to a HARQ process for DL ​​reception. In one example, the WTRU may link a first HARQ process and a second HARQ process, wherein the first HARQ process is associated with a first HARQ buffer and a first TTI length, and the second HARQ process is associated with the first HARQ buffer and a second TTI length. Further, the WTRU may use the linked first HARQ process and the first HARQ buffer to receive data for the first TB. The WTRU also receives a DL grant. The WTRU may then determine that the received DL grant is for receiving a new transmission for the linked second HARQ process. Further, the WTRU may release the first HARQ buffer based on determining that the received DL grant is for receiving a new transmission for the linked second HARQ process. And, the WTRU may use the linked second HARQ process and the first HARQ buffer to receive data for the second TB for the new transmission. Further, the WTRU may replace the data in the first HARQ buffer with the data received for the second TB.

[0276] In another example, the HARQ buffer may be used for soft combining processing. For example, the first HARQ buffer may be used for soft combining processing. In another example, the HARQ buffer may be located in a soft buffer memory. For example, the first HARQ buffer may be located in a soft buffer memory.

[0277] The WTRU may have a set of capabilities that it may signal or send to the eNode B. These capabilities may include its storage capabilities in, for example, DL, UL, and / or SL.

[0278] For example, the WTRU may have a capability regarding the number of soft channel bits that it can support in the DL. The number of soft channel bits may represent the number of soft channel bits that can be provided to a HARQ process (e.g., in the DL). The number of soft channel bits may be the number of soft channel bits that can be used for an nTTI HARQ process.

[0279] The WTRU may have the capability to indicate the number of separate soft channel bits available to it for sTTI HARQ processing. Also, the WTRU may have the capability to indicate that the WTRU has no additional soft channel bits available for sTTI HARQ processing, and as an example, the WTRU may or may need to use bits available for nTTI HARQ processing for sTTI HARQ processing.

[0280] As an example, when the WTRU does not have additional or sufficient additional soft channel bits available for sTTI HARQ processing, the WTRU may use processing for linked, shared and / or overlapping HARQ processes and / or buffers. For example, when the WTRU does not have additional or sufficient additional soft channel bits available for sTTI HARQ processing, the eNodeB may configure the WTRU to use processing for linked, shared and / or overlapping HARQ processes and / or buffers. The eNodeB may configure the WTRU to use processing for linked, shared and / or overlapping HARQ processes and / or buffers based at least on the WTRU's capability related to bits used for sTTI HARQ processing.

[0281] The WTRU may have a capability that may indicate or may be used to determine the amount of memory that the WTRU can support in the UL. For example, the WTRU may have a capability related to the maximum UL-SCH transport block bits transmitted within a TTI, which may be used to determine the amount of memory that the WTRU can support in the UL.

[0282] The WTRU may have the capability to indicate that the WTRU has no additional memory available for sTTI HARQ processing, and as an example, the WTRU may or may need to use memory available for nTTI HARQ processing for sTTI HARQ processing. And as an example, when the WTRU has no additional or sufficient additional memory available for sTTI HARQ processing, the WTRU may use processing for linking, sharing and / or overlapping HARQ processes and / or buffers.

[0283] For example, when the WTRU does not have additional or sufficient additional memory available for sTTI HARQ processing, the eNodeB may configure the WTRU to use processing for chained, shared and / or overlapping HARQ processes and / or buffers. The eNodeB may configure the WTRU to use processing for chained, shared and / or overlapping HARQ processes and / or buffers based at least on the capabilities that the WTRU has with respect to memory for sTTI HARQ processing. The configuration and use of processing for chained, shared and / or overlapping HARQ processes and / or buffers may be independent and / or different for at least one of the UL, DL, and SL (e.g., based on the capabilities of the WTRU for each).

[0284] Although the features and elements are described above in specific combinations, it will be recognized by those skilled in the art that each feature or element can be used alone or in any combination with other features and elements. In addition, the methods described herein can be implemented in a computer program, software or firmware introduced into a computer-readable medium for operation by a computer or processor. Examples of computer-readable media include electrical signals (transmitted via a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include but are not limited to read-only memory (ROM), random access memory (RAM), registers, buffer memory, semiconductor storage devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and digital versatile disks (DVDs). A processor associated with the software can be used to implement a radio frequency transceiver used in a WTRU, UE, terminal, base station, RNC or any computer host.

Claims

1. A method for use in a wireless transmit / receive unit WTRU, the method comprising: receiving first UL-DL configuration information indicating a first uplink UL-downlink DL configuration; receiving second UL-DL configuration information indicating a second UL-DL configuration; receiving a physical downlink shared channel (PDSCH) transmission in a DL direction of one or more first symbols in a first subframe, wherein the DL direction of the one or more first symbols is based on the first UL-DL configuration and the second UL-DL configuration; and A first ACK / NACK information is sent in a UL direction of one or more second symbols in the first subframe, wherein the first ACK / NACK information is based on the PDSCH transmission, and wherein the UL direction of the one or more second symbols is based on the first UL-DL configuration and the second UL-DL configuration.

2. The method according to claim 1, wherein: The first ACK / NACK information is sent in a physical uplink control channel PUCCH transmission.

3. The method according to claim 1, wherein: The first ACK / NACK information is sent in a physical uplink shared channel PUSCH transmission.

4. The method according to claim 1, wherein: Second ACK / NACK information is sent on the PUCCH in at least one of the first subframe and the second subframe.

5. The method according to claim 1, wherein: The first UL-DL configuration information is received via broadcast signaling.

6. The method according to claim 1, wherein: The first UL-DL configuration information is received via radio resource control RRC signaling.

7. The method according to claim 1, wherein: The second UL-DL configuration information is received via dynamic signaling.

8. The method according to claim 1, wherein: The second UL-DL configuration information is received via downlink control information DCI.

9. The method according to claim 1, wherein: The first UL-DL configuration information is received in the first subframe.

10. The method according to claim 1, wherein: The second UL-DL configuration information is received in the first subframe.

11. A wireless transmit / receive unit WTRU, the WTRU comprising: transceiver; as well as a processor operatively coupled to the transceiver; wherein: The transceiver is configured to receive first UL-DL configuration information indicating a first uplink UL-downlink DL configuration; the transceiver is configured to receive second UL-DL configuration information indicating a second UL-DL configuration; The transceiver is configured to receive a physical downlink shared channel (PDSCH) transmission in a DL direction of one or more first symbols in a first subframe, wherein the DL direction of the one or more first symbols is based on the first UL-DL configuration and the second UL-DL configuration; and The transceiver and the processor are configured to send first acknowledgment ACK / negative ACK / NACK information in a UL direction of one or more second symbols in the first subframe, wherein the first ACK / NACK information is based on the PDSCH transmission, and wherein the UL direction of the one or more second symbols is based on the first UL-DL configuration and the second UL-DL configuration.

12. The WTRU of claim 11, wherein the first ACK / NACK information is transmitted in a Physical Uplink Control Channel (PUCCH) transmission.

13. The WTRU of claim 11, wherein the first ACK / NACK information is transmitted in a Physical Uplink Shared Channel (PUSCH) transmission.

14. The WTRU of claim 11, wherein second ACK / NACK information is transmitted on a PUCCH in at least one of the first subframe and the second subframe.

15. The WTRU of claim 11, wherein the first UL-DL configuration information is received via broadcast signaling.

16. The WTRU of claim 11, wherein the first UL-DL configuration information is received via radio resource control (RRC) signaling.

17. The WTRU of claim 11, wherein the second UL-DL configuration information is received via dynamic signaling.

18. The WTRU of claim 11, wherein the second UL-DL configuration information is received via downlink control information (DCI).

19. The WTRU of claim 11 wherein the first UL-DL configuration information is received in the first subframe.

20. The WTRU of claim 11 wherein the second UL-DL configuration information is received in the first subframe.

21. A method for use in a wireless transmit / receive unit (WTRU), the method comprising: receiving first uplink (UL)-downlink (DL) configuration information indicating a first UL-DL configuration for a first set of physical resource blocks (PRBs); receiving second UL-DL configuration information indicating a second PRB set, wherein the second PRB set is adjacent to the first PRB set in frequency; receiving a physical downlink shared channel (PDSCH) transmission in a DL direction for one or more first time units in the first PRB set, wherein the DL direction for the one or more first time units is based on the first UL-DL configuration; and A first acknowledgment (ACK) / negative ACK (NACK) information is sent in the UL direction of one or more second time units in the second PRB set, wherein the first ACK / NACK information is based on the PDSCH transmission, and wherein the UL direction of the one or more second time units is based on the second UL-DL configuration, wherein the second UL-DL configuration is based on the first UL-DL configuration.

22. The method according to claim 21, wherein: The first ACK / NACK information is sent in a physical uplink control channel (PUCCH) transmission.

23. The method according to claim 21, wherein: The first ACK / NACK information is sent in a physical uplink shared channel PUSCH transmission.

24. The method according to claim 21, wherein: The first UL-DL configuration includes a DL direction in a time unit of the one or more second time units, and the second UL-DL configuration includes a UL direction of the time unit of the one or more second time units.

25. The method according to claim 21, wherein: The first UL-DL configuration information is received via broadcast signaling.

26. The method according to claim 21, wherein: The first UL-DL configuration information is received via radio resource control (RRC) signaling.

27. The method of claim 21, wherein: The second UL-DL configuration information is received via RRC signaling.

28. The method of claim 21, wherein: The second UL-DL configuration information is received via dynamic signaling.

29. The method according to claim 21, wherein: The first UL-DL configuration information is received via downlink control information (DCI).

30. The method of claim 21, wherein: The second UL-DL configuration information is received via DCI.

31. A wireless transmit / receive unit (WTRU), the WTRU comprising: transceiver; as well as a processor operably connected to the transceiver; wherein: The transceiver is configured to receive first uplink (UL)-downlink (DL) configuration information indicating a first uplink (UL)-downlink (DL) configuration for a first set of physical resource blocks (PRBs); The transceiver is configured to receive second UL-DL configuration information indicating a second PRB set, wherein the second PRB set is adjacent to the first PRB set in frequency; the transceiver being configured to receive a physical downlink shared channel (PDSCH) transmission in a DL direction of one or more first time units in the first PRB set, wherein the DL direction of the one or more first time units is based on the first UL-DL configuration; and The processor and the transceiver are configured to send first acknowledgement (ACK) / negative ACK (NACK) information in a UL direction of one or more second time units in the second PRB set, wherein the first ACK / NACK information is based on the PDSCH transmission, and wherein the UL direction of the one or more second time units is based on the second UL-DL configuration, wherein the second UL-DL configuration is based on the first UL-DL configuration.

32. The WTRU of claim 31 , wherein the first ACK / NACK information is transmitted in a physical uplink control channel (PUCCH) transmission.

33. The WTRU of claim 31 , wherein the first ACK / NACK information is transmitted in a physical uplink shared channel (PUSCH) transmission.

34. The WTRU of claim 31 , wherein the first UL-DL configuration comprises a DL direction in a time unit of the one or more second time units, and the second UL-DL configuration comprises a UL direction of the time unit of the one or more second time units.

35. The WTRU of claim 31 , wherein the first UL-DL configuration information is received via broadcast signaling.

36. The WTRU of claim 31 , wherein the first UL-DL configuration information is received via radio resource control (RRC) signaling.

37. The WTRU of claim 31 , wherein the second UL-DL configuration information is received via RRC signaling.

38. The WTRU of claim 31 , wherein the second UL-DL configuration information is received via dynamic signaling.

39. The WTRU of claim 31 , wherein the first UL-DL configuration information is received via downlink control information (DCI).

40. The WTRU of claim 31 , wherein the second UL-DL configuration information is received via a DCI.

41. A method for use in a wireless transmit / receive unit (WTRU), the method comprising: Receive downlink data; Uplink data is sent in a short physical uplink control channel (sPUCCH) transmission in an uplink pilot time slot (UpPTS); wherein the uplink data is based on the downlink data.

42. The method according to claim 41, wherein: The uplink data is sent in a sounding reference signal (SRS) resource.

43. The method of claim 42, wherein: The SRS resource is an SRS type 0 resource.

44. The method of claim 42, wherein: The SRS resource is an SRS type 1 resource.

45. The method of claim 41, wherein: The uplink data is transmitted in a Multicast Broadcast Single Frequency Network (MBSFN) subframe.

46. ​​A wireless transmit / receive unit (WTRU), the WTRU comprising: transceiver; as well as a processor operatively coupled to the transceiver; wherein: The transceiver is configured to receive downlink data; The transceiver and the processor are configured to send uplink data in a short physical uplink control channel (sPUCCH) transmission in an uplink pilot time slot (UpPTS); wherein the uplink data is based on the downlink data.

47. The WTRU of claim 46, wherein the uplink data is transmitted in a sounding reference signal (SRS) resource.

48. The WTRU of claim 47, wherein the SRS resource is an SRS type 0 resource.

49. The WTRU of claim 47, wherein the SRS resource is an SRS Type 1 resource.

50. The WTRU of claim 46, wherein the uplink data is transmitted in a multicast-broadcast single frequency network (MBSFN) subframe.

51. A wireless transmit / receive unit (WTRU), the WTRU comprising: transceiver; as well as a processor operatively coupled to the transceiver; wherein: The transceiver is configured to receive physical uplink control channel (PUCCH) configuration information indicating a plurality of PUCCH formats, wherein a first PUCCH format of the plurality of PUCCH formats is a short PUCCH format, and a second PUCCH format of the plurality of PUCCH formats is a long PUCCH format, wherein a length of the short PUCCH format is one or two orthogonal frequency division multiplexing (OFDM) symbols, and a length of the long PUCCH format is more than two OFDM symbols; The transceiver is configured to receive downlink control information (DCI) indicating resource and timing information for PUCCH transmission; The transceiver and the processor are configured to transmit the PUCCH transmission using the short PUCCH format based on the determined number of control bits for transmission.

52. The WTRU of claim 51 , wherein the transceiver and the processor are further configured to transmit another PUCCH transmission using the long PUCCH format based on a determined number of control bits being greater than the number of control bits required for the short PUCCH format.

53. A WTRU according to claim 51, wherein the transceiver is configured to receive a physical downlink shared channel (PDSCH) transmission using a first number of OFDM symbols, and to receive data retransmissions of the PDSCH transmission in a different subframe using a second number of OFDM symbols, and the first number and the second number are different.

54. The WTRU of claim 53, wherein the PDSCH transmission is received in a first subframe and the retransmission of the data of the PDSCH transmission is received in a second subframe, wherein the first subframe has a different time structure than the second subframe.

55. The WTRU of claim 54, wherein the first subframe has a different cyclic prefix length than the second subframe.

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