Method and apparatus for wireless communication

Abstract

Methods, systems, and apparatus for wireless communications are described. A base station may allocate resources for communication with a user equipment (UE). The resources may include one or more subframes, and each subframe may include one or more shortened transmission time intervals (sTTIs). A transmission direction may be assigned to each sTTI according to a time division duplex (TDD) mode. Based on traffic demand and / or interference from other UEs and / or base stations, the base station may determine to modify the TDD mode for communication. Accordingly, the base station may send an indicator in a control message or control region of a TTI or sTTI to indicate to the user that the transmission direction of the sTTI in the TDD mode is changed. The user may then communicate with the base station according to the reconfigured TDD mode.

Description

[0001] This application is a divisional application of the Chinese patent application with the application date of September 15, 2017, application number 201780058500.2, and invention name “Method and Apparatus for Wireless Communication”.

[0002] Cross-references

[0003] This patent application claims priority to U.S. patent application No. 15 / 704,733, filed by Hosseini et al. on September 14, 2017, entitled “Dynamic Time Division Duplexing”; and U.S. provisional patent application No. 62 / 400,049, filed by Hosseini et al. on September 26, 2016, entitled “Dynamic Time Division Duplexing for Low Latency Applications”; each of which is assigned to the assignee of this application. Background Art

[0004] The following relates generally to wireless communications, and more particularly to dynamic time division duplexing (TDD).

[0005] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, broadcast, and the like. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems (e.g., Long Term Evolution (LTE) systems). A wireless multiple-access communication system may include multiple base stations, each of which simultaneously supports communication for multiple communication devices (which may otherwise be referred to as user equipment (UE)).

[0006] These wireless multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at local, national, regional, and even global levels. One exemplary telecommunication standard is LTE. LTE is designed to improve spectrum efficiency, reduce costs, improve services, utilize new spectrum, and better integrate with other open standards. LTE can use OFDMA on the downlink (DL), single carrier frequency division multiple access (SC-FDMA) on the uplink (UL), and multiple input multiple output (MIMO) antenna technology.

[0007] A base station may use a transmission time interval (TTI) of reduced length to transmit to one or more UEs. This TTI may be referred to as a shortened TTI (sTTI) and users communicating using sTTI may be low-latency users. sTTI may be a subset of one or more subframes corresponding to a traditional TTI. The base station may allocate transmission resources for sTTI to the UE based on a time division duplex (TDD) mode, where each sTTI is designated for uplink transmission or downlink transmission according to the TDD mode. However, these TDD modes may be inappropriate in view of changing business demands or interference from other UEs. Therefore, efficient techniques that support dynamic allocation of resources to sTTI (e.g., for low-latency users) are desired. Summary of the Invention

[0008] A method of wireless communication is described. The method may include receiving a first control message within a first control region of a first transmission time interval (TTI) having a first duration; receiving a second control message within a second control region of a second TTI having a second duration less than the first duration; receiving a time division duplex (TDD) mode indicator for the second TTI in the first control region or the second control region; and determining a TDD mode for the second TTI based at least in part on the received TDD mode indicator, wherein the TDD mode changes a transmission direction for the second TTI.

[0009] Another apparatus for wireless communication is described. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. The instructions are operable to cause the processor to: receive a first control message within a first control region having a first duration; receive a second control message within a second control region having a second duration less than the first duration; receive a TDD mode indicator for the second TTI in the first control region or the second control region; and determine a TDD mode for the second TTI based at least in part on the received TDD mode indicator, wherein the TDD mode changes a transmission direction for the second TTI.

[0010] A method of wireless communication is described. The method may include: sending a first control message within a first control region having a first duration; sending a second control message within a second control region having a second duration less than the first duration; determining a TDD mode for the second TTI, wherein the TDD mode changes a transmission direction for the second TTI; and sending a TDD mode indicator in the first control region or the second control region, the TDD mode indicator identifying the determined TDD mode for the second TTI.

[0011] Another apparatus for wireless communication is described. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. The instructions are operable to cause the processor to: send a first control message within a first control region having a first duration; send a second control message within a second control region having a second duration less than the first duration; determine a TDD mode for the second TTI, wherein the TDD mode changes a transmission direction for the second TTI; and send a TDD mode indicator in the first control region or the second control region, the TDD mode indicator being used to identify the determined TDD mode for the second TTI. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 According to aspects of the present disclosure, an example of a wireless communication system supporting dynamic time division duplexing (TDD) is shown;

[0013] Figure 2 According to aspects of the present disclosure, an example of a wireless communication system supporting dynamic TDD is shown;

[0014] Figure 3-5 According to aspects of the present disclosure, an example of a resource allocation graph supporting dynamic TDD is shown;

[0015] Figure 6 According to aspects of the present disclosure, an example of HARQ signaling in a system supporting dynamic TDD is shown;

[0016] Figures 7 to 9 According to aspects of the present disclosure, a block diagram of a device supporting dynamic TDD is shown;

[0017] Figure 10 According to aspects of the present disclosure, a block diagram of a system including a UE supporting dynamic TDD is shown;

[0018] Figures 11 to 13According to aspects of the present disclosure, a block diagram of a device supporting dynamic TDD is shown;

[0019] Figure 14 According to aspects of the present disclosure, a block diagram of a system including a base station supporting dynamic TDD is shown;

[0020] Figures 15 to 23 According to aspects of the present disclosure, a method for dynamic TDD is shown. DETAILED DESCRIPTION

[0021] The resources allocated for communication can be used for uplink and downlink communications carried out within a transmission time interval (TTI) of reduced length (e.g., a shortened TTI (sTTI)). Wireless communication systems that support low-latency communication may encounter multiple challenges, including the need to efficiently support multiple low-latency users and traditional users while allowing adaptation to data service demands and interference from other UEs. In some cases, time division duplex (TDD) mode can be used to allocate resources to UE. However, static TDD mode may not be suitable for service demands and interference from other UEs. Therefore, the system (which may be a low-latency system in some examples) can support dynamic configuration of the TDD mode, which allows the base station and UE to adapt to data service demands and interference from other UEs.

[0022] In one example, a base station may define a TDD mode for a certain time frame (e.g., 10ms, 20ms, etc.) (which may be a single TTI). The TDD mode may determine the transmission direction (e.g., uplink or downlink) of a symbol in a given time frame. In some cases, an sTTI may include one or more symbols in a time frame, and each sTTI may support a specific transmission direction. In addition, there may be a guard band between certain sTTIs to support UEs switching between uplink transmission and downlink reception. Depending on business needs and interference from other UEs and / or base stations, the base station may reconfigure the transmission direction of the sTTI. For example, the base station may send control information to multiple UEs in a broadcast message or to a single UE in a unicast message, which control information is used to indicate that the transmission direction of the sTTI is being changed. The control information may include an indication of the TDD mode to be used for the sTTI. Depending on the change, the UE may allocate more uplink resources for transmission to the base station or more downlink resources for reception from the base station. The frequency or period of reconfiguration may be based on a balance between signaling overhead and resource allocation flexibility.

[0023] The aspects of the present disclosure described above are described below in the context of a wireless communication system. Aspects of the present disclosure are subsequently illustrated using a resource allocation diagram. Aspects of the present disclosure are also illustrated and subsequently described with reference to apparatus diagrams, system diagrams, and flow charts related to dynamic TDD.

[0024] Figure 1 According to various aspects of the present disclosure, an example of a wireless communication system 100 is shown. The wireless communication system 100 includes a base station 105, a UE 115, and a core network 130. In some examples, the wireless communication system 100 can be an LTE (or advanced LTE) or a new radio (NR) network. In some cases, the wireless communication system 100 can support enhanced broadband communication, ultra-reliable (i.e., mission-critical) communication, low-latency communication, and communication with low-cost and low-complexity devices, and can operate in the millimeter wave (mmW) spectrum.

[0025] Base stations 105 can communicate wirelessly with UEs 115 via one or more base station antennas. Each base station 105 can provide communication coverage for a corresponding geographic coverage area 110. The communication links 125 shown in wireless communication system 100 can include uplink transmissions from UE 115 to base station 105, or downlink transmissions from base station 105 to UE 115. UEs 115 can be dispersed throughout wireless communication system 100, and each UE 115 can be fixed or mobile. UE 115 can also be referred to as a mobile station, subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or some other appropriate terminology. UE 115 may also be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a personal electronic device, a handheld device, a personal computer, a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, a machine type communication (MTC) device, an appliance, an automobile, etc.

[0026] In some cases, UE 115 can communicate directly with other UEs (e.g., using a peer-to-peer (P2P) or device-to-device (D2D) protocol). One or more UEs 115 in a group of UEs 115 utilizing D2D communication may be within the coverage area 110 of a cell. Other UEs 115 in the group may be outside the coverage area 110 of the cell or otherwise unable to receive transmissions from the base station 105. In some cases, multiple groups of UEs 115 communicating via D2D communication may utilize a one-to-many (1:M) system, wherein each UE 115 transmits to each other UE 115 in the group. In some cases, the base station 105 facilitates the scheduling of resources for the D2D communication. In other cases, the D2D communication is performed independently of the base station 105.

[0027] Some UEs 115 (such as MTC or IoT devices) may be low-cost or low-complexity devices and may provide automated communication between machines, i.e., machine-to-machine (M2M) communication. M2M or MTC may refer to data communication technologies that allow devices to communicate with each other or base stations without human intervention. For example, M2M or MTC may refer to communications from devices that integrate sensors or meters to measure or capture information and relay that information to a central server or application, where the central server or application can utilize the information or present it to humans interacting with the program or application. Some UEs 115 may be designed to collect information or implement automated behavior of machines. Examples of applications for MTC devices include smart meters, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, climate and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based service billing.

[0028] In some cases, MTC devices can operate using half-duplex (one-way) communications with a reduced peak rate. MTC devices can also be configured to enter a power-saving "deep sleep" mode when not actively communicating. In some cases, MTC or IoT devices can be designed to support mission-critical functions, and the wireless communication system can be configured to provide ultra-reliable communications for these functions.

[0029] Base stations 105 can communicate with core network 130 and with each other. For example, base stations 105 can interface with core network 130 via backhaul links 132 (e.g., S1, etc.). Base stations 105 can communicate with each other directly or indirectly (e.g., via core network 130) via backhaul links 134 (e.g., X2, etc.). Base stations 105 can perform radio configuration and scheduling for communications with UE 115, or can operate under the control of a base station controller (not shown). In some examples, base stations 105 can be macro cells, small cells, hotspots, etc. In LTE / LTE-A networks (including those described herein), the term evolved Node B (eNB) can be generally used to describe base stations, and base stations 105 can also be referred to as evolved Node B (eNB) 105. One or more wireless communication systems described herein may include heterogeneous LTE / LTE-A networks, in which different types of evolved Node Bs (eNBs) provide coverage for various geographic areas. For example, each eNB or base station can provide communication coverage for a macro cell, a small cell, or other types of cells. The term "cell" may be used to describe a base station, a carrier or component carrier associated with a base station, or a coverage area (eg, sector, etc.) of a carrier or base station, depending on the context.

[0030] A base station may include or may be referred to by those skilled in the art as a base transceiver, a wireless base station, an access point, a wireless transceiver, a Node B, an evolved Node B (eNB), a Home Node B, a Home evolved Node B, a gNB, or some other appropriate term. The geographic coverage area for a base station may be divided into sectors, with a sector constituting only a portion of the coverage area. One or more wireless communication systems described herein may include different types of base stations (e.g., macro cell base stations or small cell base stations). The UEs described herein may be capable of communicating with various types of base stations and network devices, including macro eNBs, small cell eNBs, relay base stations, and the like. There may be overlapping geographic coverage areas for different technologies.

[0031] A macro cell typically covers a relatively large geographic area (e.g., a radius of several kilometers) and may allow unrestricted access by UEs with a service subscription with the network provider. Compared to a macro cell, a small cell is a lower-power base station that may operate in the same or different frequency band (e.g., licensed, unlicensed, etc.) as the macro cell. Small cells may include pico cells, femto cells, and micro cells, according to various examples. For example, a pico cell may cover a small geographic area and may allow unrestricted access by UEs with a service subscription with the network provider. A femto cell may also cover a small geographic area (e.g., a residence) and may provide restricted access by UEs associated with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG), UEs for users in a residence, etc.). An eNB for a macro cell may be referred to as a macro eNB. An eNB for a small cell may be referred to as a small cell eNB, pico eNB, femto eNB, or home eNB. An eNB may support one or more (e.g., two, three, four, etc.) cells (e.g., component carriers). The UE can communicate with various types of base stations and network devices, including macro eNBs, small cell eNBs, relay base stations, and so on.

[0032] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, broadcast, and the like. These systems can support communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include CDMA systems, TDMA systems, FDMA systems, and OFDMA systems. A wireless multiple-access communication system may include multiple base stations, each of which simultaneously supports communication for one or more communication devices (which may also be referred to as UEs).

[0033] The wireless communication system 100 may include a radio link control (RLC) layer, which connects higher layers (e.g., radio resource control (RRC) and packet data convergence protocol (PDCP)) to lower layers (e.g., the medium access control (MAC) layer). The RLC entity in the base station 105 or UE 115 can ensure that transmission packets are organized into blocks of appropriate size (corresponding to the MAC layer transport block size). The RLC layer can also ensure that packets are transmitted reliably. The transmitter can maintain a buffer of indexed RLC protocol data units (PDUs) and continue to retransmit each PDU until it receives a corresponding ACK. In some cases, the transmitter can send a polling request to determine which PDUs have been received, and the receiver can respond with a status report. Unlike the MAC layer hybrid automatic repeat request (HARQ), the RLC automatic repeat request (ARQ) may not include forward error correction (FEC) functionality. The RLC entity can operate in one of three modes: acknowledged mode (AM), unacknowledged mode (UM), and transparent mode (TM). In AM, RLC entities can perform segmentation / concatenation and ARQ. In UM, RLC entities can perform segmentation / concatenation but not ARQ. TM only performs data buffering and does not include concatenation / segmentation or ARQ. TM can be primarily used to transmit broadcast control information (e.g., Master Information Block (MIB) and System Information Block (SIB)), paging messages, and RRC connection messages.

[0034] The wireless communication system 100 may employ error correction schemes to improve the reliability of communications between the base station 105 and the UE 115. In some examples, hybrid automatic repeat request (HARQ) technology may be used as a method to ensure that data is correctly received on the communication link 125. HARQ may include a combination of error detection (e.g., using a cyclic redundancy check (CRC)), forward error correction (FEC), and retransmission (e.g., automatic repeat request (ARQ)). HARQ can improve throughput at the medium access control (MAC) layer in poor radio conditions (e.g., signal-to-interference-plus-noise (SINR) conditions). In incremental redundancy HARQ, erroneously received data may be stored in a buffer and combined with subsequent transmissions to increase the overall probability of successfully decoding the data. In some cases, redundant bits are added to each message before transmission. This may be useful in poor conditions. In other cases, redundant bits are not added to each transmission, but are retransmitted after the transmitter of the original message receives a negative acknowledgement (NACK) indicating a failed attempt to decode the information. The chain of transmissions, responses, and retransmissions may be referred to as a HARQ process. In some cases, a limited number of HARQ processes may be used for a given communication link 125.

[0035] In some cases, the base station 105 and the UE 115 may use more than one carrier to communicate. Each aggregated carrier is called a component carrier, and each component may have a bandwidth of, for example, 1.4, 3, 5, 10, 15, or 20 MHz. In some cases, the number of component carriers may be limited to, for example, a maximum of five 20 MHz carriers, giving a maximum aggregate bandwidth of 100 MHz. In frequency division duplexing (FDD), the number of aggregated carriers may be different in the downlink (DL) and uplink (UL). The number of uplink component carriers may be equal to or lower than the number of downlink component carriers. Individual component carriers may also have different bandwidths. For time division duplexing (TDD), the number of component carriers and the bandwidth of each component carrier will normally be the same for the downlink and uplink. Component carriers may be arranged in a variety of ways. For example, a carrier aggregation (CA) configuration may be based on contiguous component carriers within the same operating band, e.g., known as intra-band contiguous CA. Non-contiguous allocation may also be used, where the component carriers may be intra-band or inter-band.

[0036] The frame structure can be used to organize the physical resources in the wireless communication system 100. The frame can be a 10 ms interval, which can be further divided into 10 equally sized subframes. Each subframe can include two consecutive time slots. Each time slot can include six (6) or seven (7) OFDMA symbol periods. The base station 105 can be connected to the core network 130 via an S1 interface. The core network can be an evolved packet core (EPC), which can include at least one mobility management entity (MME), at least one serving gateway (S-GW) and at least one packet data network (PDN) gateway (P-GW). The MME can be a control node that handles signaling between the UE 115 and the EPC. All user Internet Protocol (IP) packets can be transmitted through the S-GW, which itself can be connected to the P-GW. The P-GW can provide IP address allocation and other functions. The P-GW can be connected to network operator IP services. Operator IP services can include the Internet, intranet, IP multimedia subsystem (IMS) and packet switched (PS) streaming services.

[0037] The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. At least some of the network devices (such as the base station 105) may include subcomponents such as an access network entity, which may be an example of an access node controller (ANC). Each access network entity may communicate with multiple UEs 115 through multiple other access network transport entities (each of which may be an example of a smart radio head or a transmit / receive point (TRP)). In some configurations, the various functions of each access network entity or base station 105 may be distributed across various network devices (e.g., radio heads and access network controllers) or consolidated into a single network device (e.g., base station 105).

[0038] A resource element consists of one symbol period and one subcarrier (e.g., a 15KHz frequency range). A resource block may contain 12 consecutive subcarriers in the frequency domain and, for a normal cyclic prefix in each OFDM symbol, seven (7) consecutive OFDM symbols in the time domain (1 slot), or 84 resource elements. Some resource elements may include one or more downlink reference signals (DL-RS), such as a cell-specific reference signal (CRS) or a UE-specific reference signal (UE-RS). A demodulation reference signal or discovery reference signal (DMRS or DRS) may be an example of a UE-specific reference signal. The UE-RS may be sent on a resource block associated with the PDSCH. The number of bits carried by each resource element may depend on the modulation scheme (the configuration of symbols that may be selected during each symbol period). Therefore, the more resource blocks a UE receives and the higher the modulation scheme, the higher the data rate may be.

[0039] The base station 105 can allocate resources to the UE 115 based on the static TDD configuration supported by the wireless communication system 100. In some examples, the wireless communication system 100 can support seven (7) TDD configurations, and each static TDD configuration can define a different ratio of downlink to uplink transmission resources in a frame, as well as the ordering of these downlink and uplink resources. In addition, the static TDD configuration can correspond to a static HARQ configuration that determines the timing of HARQ transmissions. In some cases, if the ratio of downlink to uplink transmission resources corresponds to the traffic demand of the UE 115 at a particular time, then a base station that employs a static TDD configuration can use resources efficiently. However, the traffic demand at the UE 115 may change, and the static TDD configuration may not allow the base station 105 to flexibly allocate resources based on the traffic demand of the UEs it serves.

[0040] As a result, the wireless communication system 100 can support enhanced interference mitigation and traffic adaptation (e-IMTA) technology. The e-IMTA technology can allow the base station to dynamically reconfigure the direction of the subframe (e.g., uplink or downlink) in a TDD configuration based on traffic demand and interference with other UEs. The indication of the reconfiguration can be included in layer-1 signaling (e.g., downlink control information (DCI)). In a system adopting e-IMTA, the base station 105 can use a downlink HARQ reference configuration (e.g., which can be a configured radio resource control (RRC)) and an uplink HARQ reference configuration (e.g., which can be a configured system information block 1 (SIB1)) to schedule HARQ transmissions. The reconfiguration period can be 10ms, 20ms, 40ms, 80ms, etc., and the period can be determined based on a balance between flexible resource allocation and signaling overhead.

[0041] The wireless communication system 100 may also support low-latency communications between a base station and one or more UEs 115 using, for example, a shortened transmission time interval (sTTI). By using sTTI, the base station can allocate a smaller set of resources to the UE 115, and as a result, the base station can communicate with multiple UEs 115 more flexibly. In some examples, sTTI can be a time slot in a subframe, or sTTI can be one or more symbols in a subframe. In some cases, the data service requirements of the base station 105 or UE 115 may change and the amount of interference received by the UE 115 may change over time. Therefore, it may be appropriate to support e-IMTA technology in low-latency communications to allocate resources based on service requirements, channel conditions, interference conditions, etc. However, the period of dynamic configuration for e-IMTA described above may not be applicable to low-latency systems because the TTI is shortened. In addition, the HARQ timing used for the above-mentioned HARQ reference configuration may not be efficient for sTTI allocation.

[0042] The wireless communication system 100 can operate in the ultra-high frequency (UHF) frequency region, using a frequency band from 700 MHz to 2600 MHz (2.6 GHz), although some networks (e.g., wireless local area networks (WLANs)) can use frequencies as high as 4 GHz. This region may also be referred to as the decimeter band, as the wavelengths range from approximately one decimeter to one meter in length. UHF waves can primarily propagate via line of sight and can be blocked by buildings and environmental features. However, these waves can penetrate walls sufficiently to provide service to UEs 115 located indoors. Compared to transmissions using the lower frequencies (and longer waves) in the high frequency (HF) or very high frequency (VHF) portions of the spectrum, transmissions using UHF waves are characterized by smaller antennas and a shorter range (e.g., less than 100 km). In some cases, the wireless communication system 100 may also utilize the extremely high frequency (EHF) portion of the spectrum (e.g., from 30 GHz to 300 GHz). This region may also be referred to as the millimeter band, as the wavelengths range from approximately one millimeter to one centimeter in length. Therefore, EHF antennas can be even smaller and more closely spaced than UHF antennas. In some cases, this can facilitate the use of antenna arrays within UE 115 (e.g., for directional beamforming). However, EHF transmissions may suffer from even greater atmospheric attenuation and a shorter range than UHF transmissions.

[0043] Thus, the wireless communication system 100 can support millimeter wave (mmW) communications between the UE 115 and the base station 105. Devices operating in the mmW or EHF bands can have multiple antennas to allow beamforming. That is, the base station 105 can use multiple antennas or antenna arrays to perform beamforming operations for directional communications with the UE 115. Beamforming (which can also be referred to as spatial filtering or directional transmission) is a signal processing technique that can be used at a transmitter (e.g., the base station 105) to form and / or steer an overall antenna beam in the direction of a target receiver (e.g., the UE 115). This can be achieved by combining the elements in the antenna array in such a way that signals sent at certain angles experience constructive interference, while other signals experience destructive interference.

[0044] A multiple-input, multiple-output (MIMO) wireless system uses a transmission scheme between a transmitter (e.g., base station 105) and a receiver (e.g., UE 115) where both the transmitter and the receiver are equipped with multiple antennas. Some portions of the wireless communication system 100 may use beamforming. For example, the base station 105 may have an antenna array comprising multiple rows and columns of antenna ports, which the base station 105 may use for beamforming in its communications with the UE 115. Signals may be sent multiple times in different directions (e.g., each transmission may be beamformed differently). A mmW receiver (e.g., UE 115) may attempt multiple beams (e.g., antenna subarrays) when receiving synchronization signals.

[0045] In some cases, the antennas of a base station 105 or a UE 115 may be located within one or more antenna arrays that may support beamforming or MIMO operations. One or more base station antennas or antenna arrays may be co-located at an antenna location, such as an antenna tower. In some cases, the antennas or antenna arrays associated with a base station 105 may be located at different geographic locations. The base station 105 may use multiple antennas or antenna arrays to perform beamforming operations for directional communications with the UE 115.

[0046] In some cases, the wireless communication system 100 can be a packet-based network operating according to a layered protocol stack. In the user plane, communications at the bearer or packet data convergence protocol (PDCP) layer can be IP-based. In some cases, the radio link control (RLC) layer can perform packet segmentation and reassembly to communicate over logical channels. The medium access control (MAC) layer can perform priority processing and multiplex logical channels into transport channels. The MAC layer can also use hybrid ARQ (HARQ) to provide retransmission at the MAC layer to improve link efficiency. In the control plane, the radio resource control (RRC) protocol layer can provide the establishment, configuration, and maintenance of an RRC connection between the UE 115 and the network device 105-c, the network device 105-b, or the core network 130 to support radio bearers for user plane data. At the physical (PHY) layer, transport channels can be mapped to physical channels.

[0047] The basic time unit (which can be T s =1 / 30,720,000 seconds) to represent the time interval in LTE or NR. f=307200Ts) organizes time resources in radio frames, which can be identified by system frame numbers (SFNs) ranging from 0 to 1023. Each frame may include ten 1 ms subframes numbered from 0 to 9. The subframe may be further divided into two 0.5 ms time slots, each of which contains 6 or 7 modulation symbol periods (depending on the length of the cyclic prefix prepended to each symbol). Excluding the cyclic prefix, each symbol contains 2048 sampling periods. In some cases, a subframe may be the minimum scheduling unit, which is also referred to as a TTI. In other cases, a TTI may be shorter than a subframe or may be dynamically selected (for example, in a short TTI burst or in a component carrier selected to use a short TTI).

[0048] A resource element may include one symbol period and one subcarrier (e.g., a 15 kHz frequency range). A resource block may contain 12 consecutive subcarriers in the frequency domain and, for a conventional cyclic prefix in each OFDM symbol, 7 consecutive OFDM symbols in the time domain (1 slot), or 84 resource elements. The number of bits carried by each resource element may depend on the modulation scheme (the configuration of symbols that may be selected during each symbol period). Therefore, the more resource blocks a UE receives and the higher the modulation scheme, the higher the data rate may be.

[0049] The wireless communication system 100 may support operation on multiple cells or carriers (a feature that may be referred to as carrier aggregation (CA) or multi-carrier operation). A carrier may also be referred to as a component carrier (CC), layer, channel, etc. The terms "carrier," "component carrier," "cell," and "channel" are used interchangeably herein. A UE 115 may be configured with multiple downlink CCs and one or more uplink CCs for carrier aggregation. Carrier aggregation may be used with both FDD and TDD component carriers.

[0050] In some cases, the wireless communication system 100 may utilize an enhanced component carrier (eCC). An eCC may be characterized by one or more features including: wider bandwidth, shorter symbol duration, shorter TTI, and a modified control channel configuration. In some cases, an eCC may be associated with a carrier aggregation configuration or a dual connectivity configuration (e.g., when multiple serving cells have suboptimal or non-ideal backhaul links). An eCC may also be configured for use in unlicensed spectrum or shared spectrum (when more than one operator is allowed to use the spectrum). An eCC characterized by a wide bandwidth may include one or more segments that may be used by UEs 115 that are unable to monitor the entire bandwidth or prefer to use a limited bandwidth (e.g., to save power).

[0051] In some cases, an eCC may utilize a different symbol duration than other CCs, which may include using a reduced symbol duration compared to the symbol duration of other CCs. A shorter symbol duration is associated with an increased subcarrier spacing. A device utilizing an eCC (such as a UE 115 or a base station 105) may transmit a wideband signal (e.g., 20, 40, 60, 80 MHz, etc.) with a reduced symbol duration (e.g., 16.67 microseconds). A TTI in an eCC may include one or more symbols. In some cases, the TTI duration (i.e., the number of symbols in a TTI) may be variable.

[0052] Shared radio frequency bands can be utilized in NR shared spectrum systems. For example, NR shared spectrum can utilize any combination of licensed, shared, and unlicensed spectrum, as well as other spectrum. The flexibility of eCC symbol duration and subcarrier spacing can allow eCC to be used across multiple spectrums. In some examples, NR shared spectrum can improve spectrum utilization and spectrum efficiency, especially through dynamic vertical (e.g., across frequency) and horizontal (e.g., across time) sharing of resources.

[0053] In some cases, the wireless system 100 can utilize both licensed and unlicensed radio frequency bands. For example, the wireless system 100 can employ LTE license-assisted access (LTE-LAA) or LTE unlicensed (LTE U) radio access technology or NR technology in an unlicensed band (such as the 5 GHz industrial, scientific and medical (ISM) band). When operating in an unlicensed radio frequency band, wireless devices (such as base stations 105 and UEs 115) can employ a listen-before-talk (LBT) process to ensure that the channel is idle before sending data. In some cases, operations in the unlicensed band can be based on a CA configuration combined with CCs operating in the licensed band. Operations in the unlicensed spectrum can include downlink transmissions, uplink transmissions, or both. Duplexing in the unlicensed spectrum can be based on frequency division duplexing (FDD), time division duplexing (TDD), or a combination of both.

[0054] Therefore, the wireless communication system 100 can support techniques for dynamically configuring sTTI using appropriate reconfiguration periods and HARQ processes. In one example, the base station 105 can define a default TDD configuration for a given time frame (e.g., 10ms, 20ms, etc.). The base station 105 can determine the period of the reconfiguration process based on a balance between signaling overhead and resource allocation flexibility. The base station 105 can use additional control signaling (e.g., by providing an indication of the TDD mode of the sTTI to be used in broadcast messages, grants, etc.) to reconfigure the transmission direction (e.g., uplink or downlink) of the sTTI in the default TDD configuration. Alternatively, the base station 105 can use a stand-alone sTTI (e.g., a stand-alone time slot) to communicate with the UE 115. Stand-alone sTTI can allow flexible TDD configuration and can be backward compatible with resource allocation in traditional subframes.

[0055] The techniques described herein can be used in various wireless communication systems, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and other systems. The terms "system" and "network" are often used interchangeably. A CDMA system can implement radio technologies such as CDMA2000 and Universal Terrestrial Radio Access (UTRA). CDMA2000 covers the IS-2000, IS-95, and IS-856 standards. IS-2000 versions are often referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856) is often referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variations of CDMA. TDMA systems can implement radio technologies such as Global System for Mobile Communications (GSM).

[0056] OFDMA systems can implement wireless technologies such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, and the like. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). 3GPP LTE and LTE-Advanced (LTE-A) are versions of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and Global System for Mobile Communications (GSM) are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). CDMA 2000 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). The techniques described herein can be used for the systems and wireless technologies mentioned in this disclosure as well as other systems and wireless technologies. Although aspects of an LTE system may be described for example purposes, and LTE terminology may be used throughout much of the description, the techniques described herein have applicability beyond LTE applications.

[0057] Figure 2 An example of a wireless communication system 200 for dynamic TDD is shown. The wireless communication system 200 includes a base station 105-a and a UE 115-a, which may be as described above with reference to Figure 1 Examples of aspects of a UE 115 are described. A base station 105-a can communicate with the UE 115-a on a carrier 205. In some examples, the base station 105-a can allocate resources for communicating with the legacy UE on the carrier 205. For example, the base station 105-a can allocate subframes 215 for communicating with the legacy UE, which include, for example, subframe 215-a, subframe 215-b, and subframe 215-c. Each of the subframes 215 can be assigned a transmission direction (e.g., uplink or downlink) based on a legacy TDD mode or configuration, and one or more subframes 215 can correspond to a legacy TTI. The legacy TDD mode or configuration can include uplink subframes for uplink transmissions, downlink subframes for downlink transmissions, special subframes for transitions between uplink and downlink, and flexible subframes for uplink and / or downlink transmissions. The traditional TDD mode or configuration may be dynamically configurable using RRC signaling or control messages (e.g., DCI). The subframe 215 may also include one or more sTTIs, and the base station 105-a may allocate sTTI communications with the UE 115-a (e.g., for low-latency communications).

[0058] In this example, subframe 215 may include TDD mode 210, which may include a downlink sTTI 220, an uplink sTTI 225, and a guard period 230. The guard period may allow the base station 105-a or the UE 115-a time to switch from a downlink mode of operation to an uplink mode of operation, and vice versa. The TDD mode may define the transmission direction of the sTTI in the resource allocation. TDD mode 210-a and TDD mode 210-b may be default TDD modes (e.g., configured using RRC signaling) deployed in subframes 215-a and 215-b, and TDD mode 210-c may be an example of a reconfigured TDD mode deployed in subframe 215-c. Additionally or alternatively, each of subframe 215-a, subframe 215-b, and subframe 215-c in subframe 215 may include two (2) time slots, and each time slot (e.g., a stand-alone time slot) may include symbols having a designated transmission direction (e.g., uplink or downlink). In some examples, TDD mode 210 may span the width of a single time slot of subframe 215. In other examples, TDD mode 210 may have different widths (e.g., spanning different numbers of one or more symbols of subframe 215). Stand-alone time slots may provide uplink resource allocations for uplink data and control signals, downlink resource allocations for downlink data and control, or any combination of uplink and downlink resource allocations. Stand-alone time slots may or may not include a guard period, depending on the structure of the stand-alone time slot and adjacent time slots (e.g., pure downlink or pure uplink). For example, where a stand-alone time slot ends with a downlink transmission direction, a guard period may not be required when a subsequent and adjacent stand-alone time slot begins with a downlink transmission direction.

[0059] In one example, the base station 105-a and the UE 115-a can be configured to communicate using a default TDD mode (e.g., TDD mode 210-a or TDD mode 210-b) for a predetermined time frame (e.g., a predetermined number of sTTIs). In some examples, the base station 105-a can evaluate the uplink data traffic on the carrier 205 and the downlink data traffic on the carrier 205. The base station 105-a can determine that the amount of data transmitted on the uplink is substantially less than the amount of data transmitted on the downlink. Additionally or alternatively, the base station 105-a can determine that the rate of successful uplink transmissions on the carrier 205 is low due to interference from other UEs 115. Therefore, the base station 105-a can determine to reconfigure the TDD mode for communication with the UE 115-a. For example, the base station 105-a may send an indicator regarding reconfiguring the transmission direction of one or more sTTIs in a subframe 215 (e.g., subframe 215-c with TDD mode 210-c). The transmission direction of one or more uplink sTTIs may be reconfigured from uplink to downlink, and the base station 105-a may have access to more resources for downlink communications with the UE 115-a. In some cases, the base station 105-a may include the indicator in a grant, such as a phase 0 grant in a physical downlink control channel (PDCCH) of a subframe 215 (e.g., subframe 215-a or subframe 215-b) or a phase 1 grant for an sTTI in the first time slot of subframe 215-c. Additionally or alternatively, the base station 105-a may include the grant in a common search space (CSS) of the control region, and the UE 115-a may monitor the common search space to receive the indicator.

[0060] In another example, the base station 105-a and the UE 115-a may communicate using stand-alone time slots. The stand-alone time slot may include symbols, and a transmission direction may be assigned to each symbol independently of the transmission direction of the corresponding subframe containing the stand-alone time slot. In some examples, the TDD mode of the stand-alone time slot may be based on a predetermined configuration, while in other examples, the TDD configuration may be flexible. As described above, the base station 105-a may evaluate the traffic conditions and interference conditions on the carrier 205. Based on the evaluation, the base station 105-a may determine to reconfigure the stand-alone time slot included in a subsequent subframe 215 (e.g., subframe 215-c) to support more downlink resource allocations and fewer uplink resource allocations. If the TDD mode of the stand-alone time slot in subframe 215-c is flexible, the base station 105-a may reconfigure the transmission direction of the sTTI in the stand-alone time slot in subframe 215-c to correspond to the TDD mode 210-c. If the TDD mode of the standalone timeslot is selected from one or more predetermined configurations, the base station 105 - a may select the standalone timeslot configuration corresponding to the TDD mode 210 - c for subsequent communications with the UE 115 - a .

[0061] The TDD mode of the stand-alone time slot for communication between the base station 105-a and the UE 115-a can be backward compatible with traditional technologies. In some examples, the stand-alone time slot can be used for low-latency communication. In some cases, the TDD mode of the stand-alone time slot can depend on the transmission direction of the traditional subframe containing the stand-alone time slot. For example, if one or more symbols are used for PDCCH transmission, the transmission direction of these symbols does not need to be reconfigured. In some cases, the PDCCH symbol can serve as a protection period for the transition between uplink and downlink operations. In addition, if one or more symbols are used for the transmission of CRS, DMRS or DRS, the transmission direction of these symbols (e.g., downlink) does not need to be reconfigured. For example, if a traditional user is scheduled to communicate using a transmission mode that depends on DMRS, the last two symbols of each time slot (e.g., symbols 5 and 6) can be assigned as downlink symbols.

[0062] Thus, the base station can use a TDD mode that assigns the downlink transmission direction to the last two (2) symbols of each time slot. Alternatively, a different DMRS pattern can be used for legacy transmission (e.g., symbols 2 and 3), and the base station 105-a can send information about the different DMRS patterns to the legacy users. As a result, the last two (2) symbols of each time slot can be used for uplink transmission. If the subframe is configured as a multicast broadcast single frequency network (MBSFN) subframe, the TDD mode of the stand-alone time slot can be flexible because reference signals (e.g., CRS and DMRS) can not be used in the MBSFN subframe.

[0063] Figure 3 An example of a resource allocation diagram 300 for dynamic TDD is shown. The base station may allocate resources for communicating with legacy UEs based on the TDD configuration. Subframe 305 may have resources allocated for downlink communications, and subframe 310 may be a special subframe (e.g., for switching between downlink and uplink) with some resources allocated for downlink communications and some resources allocated for uplink communications. Subframe 315 may contain resources allocated for uplink communications, and subframe 320 may have resources allocated for downlink communications. The base station may also allocate resources for communication with low latency UEs (e.g., sTTI). Subframe 305 may include two time slots: time slot 325 and time slot 330. Time slot 325 may be a reference subframe. Figure 2 Examples of standalone time slots described herein. In some examples, time slot 325 may include an sTTI allocated for low-latency communication. The TDD configuration (or TDD mode) of a standalone time slot (e.g., time slot 325) or a portion of a standalone time slot may vary based on traffic demand and interference in the low-latency system.

[0064] In some examples, slot 325 can correspond to a legacy downlink slot 335 and can include a PDCCH transmission 350 on symbols 0 and 1 (e.g., corresponding to symbol indices 0 and 1) and a CRS transmission 355 on symbol 4. In some cases, a low-latency user may request an indication of a reconfiguration of the transmission direction for an sTTI in slot 325 or, in some examples, for a subsequent slot (as described above with reference to FIG. Figure 2 Alternatively, a low latency user may monitor the PDCCH transmission 350 for an indication of a reconfiguration of the transmission direction for the sTTI in time slot 325 or, in some examples, for a subsequent time slot (as described above with reference to Figure 22) to monitor downlink symbol 2. For example, the PDCCH transmission 350 may include a grant indicating that resources for the sTTI are present at least at symbol 2. The low-latency user may then monitor for an indication of a reconfiguration of the transmission direction in the grant found in the control region of the sTTI at symbol 2. The number of symbols used for the PDCCH transmission 350 may depend on the bandwidth used for the PDCCH transmission 350 (e.g., 2 symbols for higher bandwidth applications, or 3 or 4 symbols for lower bandwidth applications).

[0065] In a first example, slot 325 may correspond to a low-latency downlink slot 340 that includes a downlink resource allocation 360 and an uplink resource allocation 365. The base station and UE may use the downlink and uplink resource allocations to send and receive data and control signals. The sTTI may be one (1) symbol and the ratio of uplink sTTI to downlink sTTI may be 1:4. Thus, the TDD mode of the low-latency downlink slot 340 may support downlink heavy communications between the base station and the low-latency user. Since symbol 4 is assigned as a downlink symbol in the low-latency system, the low-latency system may avoid interference with the legacy system and may successfully transmit the CRS. The low-latency downlink slot 340 may include a guard period 370 that may allow the base station or UE time to transition from a downlink mode of operation to an uplink mode of operation (e.g., within the slot or across adjacent slots). In the low-latency downlink slot 340, the guard period may not span the entire symbol period, but may span a portion of one or more symbol periods (eg, the first portion of symbol 5 and the second portion of symbol 6).

[0066] In a second example, time slot 325 can correspond to a low-latency downlink time slot 345 that also includes a downlink resource allocation 360 and an uplink resource allocation 365. The base station and the UE can use the downlink and uplink resource allocations to send and receive data and control signals. In some cases, the sTTI can be one (1) symbol and the ratio of uplink sTTI to downlink sTTI can be 1:1. In other cases, the sTTI can be two (2) symbols and the ratio of uplink sTTI to downlink sTTI can also be 1:1. Therefore, the TDD mode of the low-latency downlink time slot 345 can support the same amount of resources for uplink and downlink communications between the base station and the low-latency users.

[0067] The low-latency downlink time slot 345 may include a guard period 370 that allows the base station or UE to have time to transition from downlink operation to uplink operation. In this example, the guard period can be aligned with the symbol period (e.g., symbol 4) that can be used for CRS transmission 355. Since symbol 4 is used as a guard period, the low-latency system user can skip monitoring this symbol. Therefore, the low-latency system can avoid interference with the traditional system and can successfully transmit CRS. However, in some cases, it may be appropriate to have the low-latency user monitor symbol 4 for CRS transmission 355 in order to perform the channel estimation process. Therefore, in another example, symbol 4 can be assigned as a downlink symbol, and the guard period can span symbol 5. Since the last symbol in the low-latency downlink time slot 345 is assigned as an uplink symbol, the base station can assign the first symbol of the time slot 330 as a guard period before switching to downlink operation. However, this can reduce efficiency because fewer symbol periods are available for communication in the time slot 330.

[0068] Figure 4 An example of a resource allocation diagram 400 for dynamic TDD is shown. A base station may allocate resources for communicating with legacy UEs according to a TDD configuration. Subframe 405 may have resources allocated for downlink communications, subframe 410 may be a special subframe (e.g., for switching between downlink and uplink) with some resources allocated for downlink communications and some resources allocated for uplink communications, subframe 415 may contain resources allocated for uplink communications, and subframe 420 may be allocated for downlink communications.

[0069] The base station may also allocate resources (eg, sTTI) for communication with low-latency UEs. Subframe 405 may include time slot 425 and time slot 430. Time slot 430 may be a reference time slot. Figure 2 An example of a standalone time slot described. In some examples, time slot 430 can include an sTTI allocated for low latency communications. The TDD configuration (or TDD mode) of a standalone time slot (e.g., time slot 425) can vary based on traffic demand and interference in the low latency system. In this example, time slot 430 can correspond to a traditional downlink time slot 435 and can include CRS transmissions 450 on symbol 1 and symbol 4. In some cases, a low latency user may request an indication of a reconfiguration of the transmission direction of the sTTI in time slot 430 and, in some examples, for subsequent time slots (as described above with reference to Figure 2 described) to monitor downlink symbol 1.

[0070] In a first example, time slot 430 may correspond to a low-latency downlink time slot 440 including a downlink resource allocation 455 and an uplink resource allocation 460. The base station and the UE may use the downlink and uplink resource allocations to send and receive data and control signals. The sTTI may be one (1) symbol and the ratio of uplink sTTI to downlink sTTI may be 1:2. Alternatively, the sTTI may be two (2) symbols and the ratio of uplink sTTI to downlink sTTI may be 1:2. Thus, the TDD mode of the low-latency downlink time slot 440 may support downlink heavy communications between the base station and the low-latency users.

[0071] Since symbol 7 of low-latency downlink slot 440 is assigned as a downlink symbol in a low-latency system, the low-latency system can avoid interference with the legacy system and can successfully transmit CRS. Alternatively, since symbol 11 is assigned as a guard period, the low-latency user can skip monitoring this symbol and the low-latency system can avoid interference with the legacy system. The low-latency downlink slot 440 may include a guard period 465, which allows the base station or UE to have time to transition from downlink operation to uplink operation. In this example, symbol 6 of slot 425 can be assigned as a guard period to transition from uplink operation to downlink operation. In another example, symbol 7 of slot 430 can be assigned as a guard period to allow the base station or UE to transition from uplink operation to downlink operation. In the low-latency downlink slot 440, the guard period can be aligned with the symbol period (e.g., symbol 11).

[0072] In a second example, time slot 430 may correspond to a low-latency downlink time slot 445 that also includes a downlink resource allocation 455 and an uplink resource allocation 460. The base station and UE may use the downlink and uplink resource allocations to send and receive data and control signals. In some cases, the sTTI may be one (1) symbol and the ratio of uplink sTTI to downlink sTTI may be 1:5. Thus, the TDD mode of the low-latency downlink time slot 445 may support downlink heavy (e.g., where the downlink channel has a higher load than the uplink channel, such as where the downlink channel has a load that is more than two or three times that of the uplink channel, where a threshold for the load may be configured) communications between the base station and the low-latency users. The low-latency downlink time slot 445 may include a guard period 465 that may allow the base station or UE time to transition from a downlink mode of operation to an uplink mode of operation (e.g., within the time slot or across adjacent time slots). In the low-latency downlink slot 445, the guard period may not span the entire symbol period, but may span a portion of one or more symbol periods (e.g., the first portion of symbol 12 and the second portion of symbol 13). In another example, the first guard period may span the first portion of symbol 11, and more resources may be available for uplink transmission.

[0073] Figure 5 An example of a resource allocation diagram 500 for dynamic TDD is shown. A base station may allocate resources for communicating with legacy UEs according to a TDD configuration. Subframe 505 may have resources allocated for downlink communications, subframe 510 may be a special subframe (e.g., for switching between downlink and uplink) with some resources allocated for downlink communications and some resources allocated for uplink communications, subframe 515 may contain resources allocated for uplink communications, and subframe 520 may have resources allocated for downlink communications.

[0074] The base station may also allocate resources (e.g., sTTI) for communication with low-latency UEs. The subframe 515 may include a time slot 525, which may be the first time slot or the second time slot of the subframe 515. The time slot 525 may be a reference time slot. Figure 25. Example of a standalone time slot described. In some examples, time slot 252 may include an sTTI allocated for low-latency communication. The TDD configuration (or TDD mode) of a standalone time slot (e.g., time slot 525) may vary based on traffic demand and interference in a low-latency system. In this example, time slot 525 may support flexible allocation of sTTIs in time slot 525 since legacy PDCCH and reference signals may not be sent on subframe 515. In some cases, legacy users may be scheduled for legacy uplink transmission 545 on the fourth symbol of the time slot.

[0075] In a first example, time slot 525 can correspond to a low-latency uplink time slot 535 including a downlink resource allocation 550 and an uplink resource allocation 555. The base station and the UE can use the downlink and uplink resource allocations to send and receive data and control signals. The sTTI can be one (1) symbol and the ratio of uplink sTTI to downlink sTTI can be 1:2. Alternatively, the sTTI can be two (2) symbols and the ratio of uplink sTTI to downlink sTTI can also be 1:2. Therefore, the TDD mode of the low-latency uplink time slot 535 can support downlink heavy communication between the base station and the low-latency users.

[0076] In some cases, the base station may allocate the first four symbols of the low-latency uplink time slot 535 as uplink symbols for communication with low-latency users. In one example, the base station may indicate to a traditional user scheduled on the fourth symbol that the fourth symbol is not available for traditional transmission. Therefore, the low-latency system can avoid interfering transmission with the traditional system. The low-latency uplink time slot 535 may include a guard period 560, which may allow the base station or UE to have time to transition from the downlink operating mode to the uplink operating mode (e.g., within a time slot or across adjacent time slots). In the low-latency uplink time slot 535, the guard period may not span the entire symbol period, but may span a portion of one or more symbol periods (e.g., the first part of the fifth symbol and the second part of the seventh symbol). The position and duration of the guard period may depend on the TDD configuration and the uplink and downlink business requirements.

[0077] In a second example, time slot 525 can correspond to a low-latency uplink time slot 540 that also includes a downlink resource allocation 550 and an uplink resource allocation 555. The base station and UE can use the downlink and uplink resource allocations to send and receive data and control signals. In some cases, the sTTI can be one (1) symbol and the ratio of uplink sTTI to downlink sTTI can be 1:1. In other cases, the sTTI can be three (3) symbols and the ratio of uplink sTTI to downlink sTTI can be 1:1. In both cases, the TDD mode of the low-latency uplink time slot 540 can support substantially the same amount of resources for uplink and downlink transmissions. The low-latency uplink time slot 540 can include a guard period 560 that allows the base station or UE time to transition from a downlink mode of operation to an uplink mode of operation (e.g., within the time slot or across adjacent time slots). In the low-latency uplink timeslot 540, the guard period may not span the entire symbol period, but may span a portion of one or more symbol periods (eg, the first portion of the fourth symbol and the second portion of the seventh symbol).

[0078] Figure 6 An example of HARQ signaling 600 for dynamic TDD is shown. The base station can allocate resources for communication with legacy UEs, and / or the base station can allocate resources for communication with low-latency users. Time period 605-a and time period 605-b can represent a set of resources in the time domain. For example, time period 605-a and time period 605-b can be examples of frames in a legacy LTE system, and time period 610 can correspond to a subframe in a legacy LTE system. Alternatively, time period 610 can correspond to a sTTI and time period 605 can correspond to a predetermined number of sTTIs. In some cases, uplink transmissions within time period 615 may or may not be received by the base station. Depending on whether the transmission is successful, the base station may send an ACK or NACK in a HARQ message within time period 620 to indicate successful or unsuccessful reception of the transmission. Similarly, downlink transmissions within time period 625 may or may not be received by the UE. Depending on whether the transmission is successful, the UE may send an ACK or a NACK in a HARQ message within time period 630 to indicate successful or unsuccessful reception of the transmission.

[0079] In a first example, time period 605 may be an example of a frame, and time period 610 may be an example of a subframe. The base station may assign different transmission directions (e.g., uplink or downlink) to different subframes based on the TDD configuration (or TDD mode). In the case where the uplink subframe is considered an anchor subframe and may not be reconfigured, the TDD configuration may be a downlink HARQ reference configuration, or in the case where the downlink subframe is considered an anchor subframe and may not be reconfigured, the TDD configuration may be an uplink HARQ reference configuration. These HARQ reference configurations may be used to ensure that resources are available for HARQ transmission in time period 605.

[0080] A low-latency user may send an uplink message during time period 615 and, based on the uplink HARQ reference configuration, receive a HARQ message responsive to the transmission seven (7) subframes later during time period 620. Similarly, the base station may send a downlink message during time period 625 and receive a HARQ message responsive to the transmission eight (8) subframes later during time period 630. In some cases, the HARQ reference configuration may be reliable because the anchor subframe may not be reconfigured and may therefore always be available for HARQ transmission. However, for low-latency applications, HARQ delays may be significant.

[0081] In a second example, time period 610 can be an example of an sTTI and time period 605 can be an example of a predetermined number of sTTIs. The base station can assign different transmission directions to different sTTIs based on the TDD configuration (or TDD mode). The sTTI can correspond to, for example, one (1) symbol, two (2) symbols, or one (1) time slot of a legacy subframe, and communications using sTTIs can be backward compatible with legacy systems. In the case where the uplink sTTI in the subframe is regarded as an anchor sTTI, the TDD configuration can be a downlink HARQ reference configuration, or in the case where the downlink sTTI is regarded as an anchor sTTI, the TDD configuration can be an uplink HARQ reference configuration. A low-latency user can send an uplink message in time period 615 and receive a HARQ message in response to the transmission in time period 620 seven (7) symbols later based on the uplink HARQ reference configuration. Similarly, the base station may transmit a downlink message during time period 625 and receive a HARQ message in response to the transmission eight (8) symbols later during time period 630. As described above, the HARQ reference configuration may be reliable because the anchor sTTI may not be reconfigured and is therefore always available for HARQ transmission. Additionally, since the HARQ reference configuration is scaled based on the length of the sTTI, HARQ latency may not be significant.

[0082] In a third example, time period 610 can be an example of an sTTI and time period 605 can be an example of a predetermined number of sTTIs. The base station can assign different transmission directions to different sTTIs based on the TDD configuration (or TDD mode). An sTTI can correspond to one (1) symbol, two (2) symbols, or one (1) time slot, and communications using sTTIs can be backward compatible with legacy systems. In some cases, a low-latency user can receive (e.g., in a grant) an indication of a value k1, k2, or both associated with HARQ timing for uplink and downlink transmissions in a particular sTTI. For example, a low-latency user can send an uplink message within time period 615. The low-latency user can then identify the value k1, k2, or both included in the grant and determine the timing of the HARQ process based on the following formula:

[0083] HARQsTTI=n+(k1*5TTI)+k2 (1)

[0084] Where n represents the index corresponding to the current sTTI, sTTI represents the length of the sTTI, and k1 and k2 are values associated with HARQ timing.

[0085] For example, for an uplink transmission in time period 615, a low-latency user may receive an indication of the values of k1 and k2 in a grant before transmission (e.g., where k1=4 and k2=3), and the low-latency user may determine that a HARQ message for the transmission was sent in time period 620. Similarly, the base station 105 may send a downlink message in time period 625 and send an indication of the value of k2 to the low-latency user (e.g., where k2=4), while the value of k1 may remain unchanged (e.g., k1=4). Subsequently, the low-latency user may send a HARQ message in time period 630 based on the values of k1, k2, and Formula 1. The values of k1 and k2 may depend on the TDD mode, interference pattern, downlink and uplink processing time, and the like. In some cases, the transmission direction of the sTTI allocated for HARQ transmission based on the values of k1, k2, or both may change in the time between the grant and the HARQ transmission. In such a case, the base station may indicate the direction change to the low-latency user and update the values of k1, k2, or both for HARQ transmissions in subsequent grants.

[0086] In a fourth example, time period 610 may be an example of an sTTI and time period 605 may be an example of a predetermined number of sTTIs. The TDD configuration (or TDD mode) of the stand-alone time slots including the sTTI may be one of the predetermined number of TDD configurations. In such a case, a HARQ association table may be defined to determine the HARQ timing for transmissions in a particular TDD configuration. For example, when a low-latency user communicates using a TDD configuration corresponding to time period 605, the low-latency user may determine that the uplink transmission in time period 615 corresponds to the HARQ message in time period 620, and that the downlink transmission in time period 625 corresponds to the HARQ message in time period 630.

[0087] Figure 7 According to various aspects of the present disclosure, a block diagram 700 of a wireless device 705 supporting dynamic TDD is shown. The wireless device 705 may be a wireless device 705 configured as described with reference to FIG. Figure 1 1. The wireless device 705 may include a receiver 710, a UE communication manager 715, and a transmitter 720. The wireless device 705 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0088] The receiver 710 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to dynamic TDD, etc.). The information may be transmitted to other components of the device. The receiver 710 may be a reference Figure 10 Examples of aspects of the transceiver 1035 are described.

[0089] UE communication manager 715 may be a reference Figure 10 Examples of aspects of the UE communication manager 1015 are described. The UE communication manager 715 may receive a first control message within a first control region having a first duration, and a second control message within a second control region having a second duration less than the first duration. The UE communication manager 715 may also receive a TDD mode indicator for the second TTI in the first control region or the second control region. In some examples, the UE communication manager 715 may determine a TDD mode for the second TTI based on the received TDD mode indicator. The TDD mode may change the transmission direction for the second TTI.

[0090] In some cases, the UE communication manager 715 may determine one or more protection periods for the TDD mode for the second TTI based at least in part on the TDD mode indicator, a first protection period in the one or more protection periods being positioned between a first portion of the TDD mode having a first transmission direction and a second portion of the TDD mode having a second transmission direction different from the first transmission direction.

[0091] In some cases, the UE communication manager 715 may receive a HARQ configuration indicator for a second TTI in the first control region or the second control region. The UE communication manager 715 may determine a HARQ configuration for the second TTI based at least in part on the received HARQ configuration indicator. The second TTI may carry HARQ information responsive to a transmission in a third TTI, where the third TTI has a third duration that is less than the first duration. In some cases, the HARQ configuration changes the transmission direction for the second TTI.

[0092] The transmitter 720 may transmit signals generated by other components of the device. In some examples, the transmitter 720 may be co-located with the receiver 710 in a transceiver module. For example, the transmitter 720 may be a reference Figure 10 Examples of aspects of the described transceiver 1035. The transmitter 720 may include a single antenna, or it may include a group of antennas.

[0093] Figure 8 According to various aspects of the present disclosure, a block diagram 800 of a wireless device 805 supporting dynamic TDD is shown. The wireless device 805 may be a wireless device 805 configured as described with reference to FIG. Figure 1 and 7 Examples of aspects of the wireless device 705 or UE 115 are described. The wireless device 805 may include a receiver 810, a UE communication manager 815, and a transmitter 820. The wireless device 805 may also include a processor. Each of these components can communicate with each other (e.g., via one or more buses).

[0094] The receiver 810 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to dynamic TDD, etc.). The information may be transmitted to other components of the device. The receiver 810 may be a reference Figure 10 Examples of aspects of the transceiver 1035 are described.

[0095] UE communication manager 815 may be a reference Figure 1010. The UE communication manager 815 may include a control message component 825, a TDD mode indicator component 830, and a TDD mode manager 835. The control message component 825 may receive a first control message within a first control region of a first TTI having a first duration. The control message component 825 may receive a second control message within a second control region of a second TTI having a second duration less than the first duration. In some cases, the second duration of the second TTI includes an integer number of symbol periods or one time slot. In some cases, the first TTI and the second TTI at least partially overlap in time.

[0096] The TDD mode indicator component 830 may receive a TDD mode indicator for the second TTI in the first control region or the second control region. In some cases, the TDD mode indicator is included in a first grant of resources received in the first control message, in a second grant of resources received in the second control message, or in a common search space in the control region for the first TTI. In some cases, the TDD mode indicator component 830 may receive a HARQ configuration indicator for the second TTI in the first control region or the second control region.

[0097] The TDD mode manager 835 may determine a TDD mode for the second TTI based on the received TDD mode indicator. The TDD mode may change the transmission direction for the second TTI. In some cases, the TDD mode manager 835 may determine a HARQ configuration for the second TTI based at least in part on the received HARQ configuration indicator. The second TTI may carry HARQ information responsive to a transmission in a third TTI, wherein the third TTI has a third duration that is less than the first duration. In some cases, the HARQ configuration changes the transmission direction for the second TTI.

[0098] The transmitter 820 may transmit signals generated by other components of the device. In some examples, the transmitter 820 may be co-located with the receiver 810 in a transceiver module. For example, the transmitter 820 may be a reference Figure 10 Examples of aspects of the described transceiver 1035. The transmitter 820 may include a single antenna, or it may include a group of antennas.

[0099] Figure 9 According to various aspects of the present disclosure, a block diagram 900 of a UE communication manager 915 supporting dynamic TDD is shown. The UE communication manager 915 may be a reference Figure 7 、 810. The UE communication manager 915 may include a control message component 920, a TDD mode indicator component 925, a TDD mode manager 930, a default TDD mode identifier 935, a TDD mode selector 940, and a TDD mode duration identifier 945. Each of these modules may communicate with each other directly or indirectly (e.g., via one or more buses).

[0100] Control message component 920 may receive a first control message within a first control region of a first time interval (TTI) having a first duration. Control message component 920 may receive a second control message within a second control region of a second time interval (TTI) having a second duration that is less than the first duration. In some cases, the second duration of the second TTI includes an integer number of symbol periods or one time slot. In some cases, the first TTI and the second TTI at least partially overlap in time.

[0101] The TDD mode indicator component 925 may receive a TDD mode indicator for a second TTI in the first control region or the second control region. In some cases, the TDD mode indicator is included in a first grant of resources received in the first control message, in a second grant of resources received in the second control message, or in a common search space in the control region of the first TTI. In some cases, the TDD mode indicator component 925 may receive a HARQ configuration indicator for the second TTI in the first control region or the second control region. Receiving the HARQ configuration indicator may include receiving an indication of an entry in an association table. The association table may indicate a temporal relationship between a TTI for transmitting HARQ information and a TTI to which the TTI for transmitting the HARQ information responds.

[0102] The TDD mode manager 930 may determine a TDD mode for the second TTI based on the received TDD mode indicator. The TDD mode may change the transmission direction for the second TTI. In some cases, the TDD mode manager 930 may identify a reference signal for the TDD mode for the first TTI. In some cases, the TDD mode manager 930 may determine to skip monitoring a symbol period during the second TTI associated with the identified reference signal. In some cases, the TDD mode manager 930 may determine one or more guard periods for the TDD mode for the second TTI based at least in part on the TDD mode indicator, a first guard period in the one or more guard periods being located between a first portion of the TDD mode having a first transmission direction and a second portion of the TDD mode having a second transmission direction different from the first transmission direction.

[0103] In some cases, the TDD mode manager 930 may determine a HARQ configuration for a second TTI based at least in part on the received HARQ configuration indicator. The second TTI may carry HARQ information responsive to a transmission in a third TTI, wherein the third TTI has a third duration that is less than the first duration. In some cases, the HARQ configuration changes the transmission direction for the second TTI.

[0104] The default TDD mode identifier 935 may identify the default TDD mode associated with the second TTI.The determined TDD mode may change the transmission direction for at least a portion of the default TDD mode.

[0105] The TDD mode selector 940 may select a TDD mode associated with a TDD mode indicator entry corresponding to the received TDD mode indicator for the second TTI. In some cases, determining the TDD mode for the second TTI includes selecting the TDD mode from a set of predetermined TDD modes based on the received TDD mode indicator. In some cases, selecting the TDD mode from the set of predetermined TDD modes includes reading a table including a set of TDD mode indicator entries associated with corresponding TDD modes.

[0106] In some cases, the TDD mode selector 940 may identify multiple reference HARQ configurations and select a HARQ configuration from the multiple reference HARQ configurations. In some cases, the TDD mode selector 940 may identify the value of a parameter of a channel used to receive the first control message and the second control message. Thus, the TDD mode selector 940 may select a HARQ configuration for the second TTI based at least in part on the value of the identified channel parameter. The channel parameter may be the length of the second TTI, or an acknowledgment transmission delay, or a downlink load, or an uplink load, or a combination thereof.

[0107] The TDD mode duration identifier 945 can identify that the determined TDD mode applies to a predetermined number of TTIs, including a second TTI having a second duration. In some cases, the TDD mode duration identifier 945 can identify a HARQ timing offset for the second TTI. The HARQ configuration indicator can identify the HARQ timing offset. Identifying the HARQ timing offset can include: identifying a value of a parameter associated with the HARQ process, and identifying the HARQ timing offset for the second TTI based at least in part on the value of the parameter of the identified channel. The parameter associated with the HARQ process can be or include a downlink load, an uplink load, an interference pattern, a downlink processing time, an uplink processing time, or a combination thereof.

[0108] Figure 10 According to various aspects of the present disclosure, a diagram of a system 1000 is shown that includes a device 1005 that supports dynamic TDD. The device 1005 may be as described above, for example, with reference to Figure 1 、 7 8 or include components of the wireless device 705, wireless device 805, or UE 115. The device 1005 may include components for two-way voice and data communication, including components for sending communications and components for receiving communications, including a UE communication manager 1015, a processor 1020, a memory 1025, software 1030, a transceiver 1035, an antenna 1040, and an I / O controller 1045. These components may communicate electronically via one or more buses (e.g., bus 1010). The device 1005 may communicate wirelessly with one or more base stations 105.

[0109] The processor 1020 may include an intelligent hardware device (e.g., a general-purpose processor, a digital signal processor (DSP), a central processing unit (CPU), a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, the processor 1020 may be configured to operate the memory array using a memory controller. In other cases, the memory controller may be integrated into the processor 1020. The processor 1020 may be configured to execute computer-readable instructions stored in the memory to perform various functions (e.g., functions or tasks for supporting dynamic TDD).

[0110] The memory 1025 may include random access memory (RAM) and read-only memory (ROM). The memory 1025 may store computer-readable, computer-executable software 1030, which includes instructions that, when executed, cause the processor to perform the various functions described herein. In some cases, the memory 1025 may also contain, among other things, a basic input / output system (BIOS), which may control basic hardware and / or software operations, such as interaction with peripheral components or devices.

[0111] The software 1030 may include code for implementing aspects of the present disclosure, including code for supporting dynamic TDD. The software 1030 may be stored in a non-transitory computer-readable medium (such as system memory or other memory). In some cases, the software 1030 may not be directly executable by a processor, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

[0112] The transceiver 1035 can communicate bidirectionally via one or more antennas, wired or wireless links, as described above. For example, the transceiver 1035 can represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver. The transceiver 1035 can also include a modem for modulating packets and providing the modulated packets to the antenna for transmission, and demodulating packets received from the antenna. In some cases, the wireless device can include a single antenna 1040. However, in some cases, the device can have more than one antenna 1040, which can simultaneously send or receive multiple wireless transmissions.

[0113] I / O controller 1045 can manage input and output signals for device 1005. I / O controller 1045 can also manage peripheral devices that are not integrated into device 1005. In some cases, I / O controller 1045 can represent a physical connection or port to an external peripheral device. In some cases, I / O controller 1045 can utilize a computer such as operating system or another known operating system.

[0114] Figure 11 According to various aspects of the present disclosure, a block diagram 1100 of a wireless device 1105 supporting dynamic TDD is shown. The wireless device 1105 may be a wireless device 1105 configured as described with reference to FIG. Figure 1 Examples of aspects of base station 105 are described. Wireless device 1105 may include a receiver 1110, a base station communication manager 1115, and a transmitter 1120. Wireless device 1105 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0115] The receiver 1110 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to dynamic TDD, etc.). The information may be transmitted to other components of the device. The receiver 1110 may be a reference Figure 14 Examples of aspects of transceiver 1435 are described.

[0116] The base station communication manager 1115 may be a reference Figure 14An example of an aspect of the base station communication manager 1415 described herein. The base station communication manager 1115 may send a first control message within a first control region having a first duration for a first TTI, and send a second control message within a second control region having a second duration for a second TTI that is less than the first duration. The base station communication manager 1115 may also determine a TDD mode for the second TTI. In some examples, the TDD mode changes the transmission direction for the second TTI. In some cases, the TDD mode includes one or more guard periods for the second TTI. In some cases, a first guard period in the one or more guard periods is located between a first portion of the TDD mode having a first transmission direction and a second portion of the TDD mode having a second transmission direction that is different from the first transmission direction. The base station communication manager 1115 may send (e.g., after determining the TDD mode) a TDD mode indicator in the first control region or the second control region, which is used to identify the determined TDD mode for the second TTI.

[0117] In some cases, the base station communication manager 1115 may determine a HARQ configuration for the second TTI, and the second TTI may carry HARQ information responsive to a transmission in a third TTI, wherein the third TTI has a third duration that is less than the first duration. The HARQ configuration changes the direction of transmission for the second TTI. In some cases, the base station communication manager 1115 may send a HARQ configuration indicator in the first control region or the second control region, which identifies the determined HARQ configuration for the second TTI.

[0118] The transmitter 1120 may transmit signals generated by other components of the device. In some examples, the transmitter 1120 may be co-located with the receiver 1110 in a transceiver module. For example, the transmitter 1120 may be a reference Figure 14 Examples of aspects of the described transceiver 1435. The transmitter 1120 may include a single antenna, or it may include a group of antennas.

[0119] Figure 12 According to various aspects of the present disclosure, a block diagram 1200 of a wireless device 1205 supporting dynamic TDD is shown. The wireless device 1205 may be as described with reference to Figure 1 and 11 Examples of aspects of the wireless device 1105 or base station 105 are described. The wireless device 1205 may include a receiver 1210, a base station communication manager 1215, and a transmitter 1220. The wireless device 1205 may also include a processor. Each of these components can communicate with each other (e.g., via one or more buses).

[0120] The receiver 1210 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to dynamic TDD, etc.). The information may be transmitted to other components of the device. The receiver 1210 may be a reference Figure 14 Examples of aspects of transceiver 1435 are described.

[0121] The base station communication manager 1215 may be a reference Figure 14 Examples of aspects of the base station communications manager 1415 are described. The base station communications manager 1215 can include a control message component 1225, a TDD mode manager 1230, and a TDD mode indicator component 1235.

[0122] The control message component 1225 can send a first control message within a first control region having a first TTI having a first duration, and send a second control message within a second control region having a second TTI having a second duration less than the first duration. In some cases, the second duration includes or consists of an integer number of symbol periods or one time slot.

[0123] The TDD mode manager 1230 may determine a TDD mode for the second TTI. The TDD mode may change the transmission direction for the second TTI. In some cases, the TDD mode manager 1230 may determine the TDD mode for the second TTI based on the identified transmission direction. In some cases, the TDD mode manager 1230 may determine the TDD mode for the second TTI based on the identified transmission direction associated with the time interval adjacent to the second TTI. In some cases, the TDD mode for the second TTI includes at least one of the following: downlink resources, or uplink resources, or one or more guard periods, or any combination thereof. In some cases, the TDD mode manager 1230 may determine a HARQ configuration for the second TTI, and the second TTI may carry HARQ information in response to a transmission in a third TTI, wherein the third TTI has a third duration that is smaller than the first duration. The HARQ configuration may change the transmission direction for the second TTI.

[0124] In some cases, the TDD mode includes or consists of one or more guard periods of the second TTI. In such an example, a first guard period of the one or more guard periods may be located between a first portion of the TDD mode having a first transmission direction and a second portion of the TDD mode having a second transmission direction different from the first transmission direction. One or more of the guard periods may have a duration that is less than a symbol period. In some examples, a first boundary of a guard period of the plurality of guard periods is aligned with a symbol period of the TDD mode for the first TTI, and a second boundary of the guard period is not aligned with a symbol period of the TDD mode for the first TTI.

[0125] In some cases, the TDD mode manager 1230 may identify a third transmission direction associated with a third portion of a third TTI. The third TTI may follow the second TTI. In such a case, the TDD mode for the second TTI may include a second protection period in one or more protection periods. The second protection period may be placed at the end of the second TTI between the third portion and the second portion of the TDD mode having the second transmission direction. The second transmission direction may be different from the third transmission direction.

[0126] In some cases, the TDD mode manager 1230 may identify a third transmission direction associated with a third portion of a third TTI. The third TTI may precede the second TTI. In such a case, the TDD mode for the second TTI may include a second protection period in one or more protection periods. The second protection period may be placed at the beginning of the second TTI between the third portion and the first portion of the TDD mode having the first transmission direction. The first transmission direction may be different from the third transmission direction.

[0127] The TDD mode indicator component 1235 may transmit a TDD mode indicator in the first control region or the second control region to identify the determined TDD mode for the second TTI. The TDD mode indicator component 1235 may transmit the TDD mode indicator in a first grant of resources received in a first control message, in a second grant of resources received in a second control message, or in a common search space in the control region for the first TTI. In some cases, the TDD mode indicator component 1235 may transmit a HARQ configuration indicator in the first control region or the second control region to identify the determined HARQ configuration for the second TTI.

[0128] The transmitter 1220 may transmit signals generated by other components of the device. In some examples, the transmitter 1220 may be co-located with the receiver 1210 in a transceiver module. For example, the transmitter 1220 may be a reference Figure 14Examples of aspects of the described transceiver 1435. The transmitter 1220 may include a single antenna, or it may include a group of antennas.

[0129] Figure 13 According to various aspects of the present disclosure, a block diagram 1300 of a base station communication manager 1315 supporting dynamic TDD is shown. The base station communication manager 1315 may be a reference Figure 11 、 12 14 and 15. The base station communication manager 1315 may include a control message component 1320, a TDD mode manager 1325, a TDD mode indicator component 1330, a default TDD mode identifier 1335, a transmission direction identifier 1340, a guard period manager 1345, and a reference signal manager 1350. Each of these modules can communicate with each other directly or indirectly (e.g., via one or more buses).

[0130] The control message component 1320 may send a first control message within a first control region having a first TTI having a first duration, and send a second control message within a second control region having a second TTI having a second duration that is less than the first duration. In some cases, the control message component 1320 may identify a value of a parameter of a channel used to send the first control message and the second control message. The channel parameter may be or include the length of the second TTI, an acknowledgment transmission delay, a downlink load, an uplink load, or a combination thereof.

[0131] The TDD mode manager 1325 may determine a TDD mode for the second TTI. The TDD mode may change the transmission direction for the second TTI. The TDD mode manager 1325 may determine the TDD mode for the second TTI based on the identified transmission direction, and / or determine the TDD mode for the second TTI based on the identified transmission direction associated with the time interval adjacent to the second TTI. In some cases, the TDD mode for the second TTI includes at least one of the following: downlink resources, uplink resources, one or more guard periods, or any combination thereof.

[0132] In some cases, the TDD mode manager 1325 may determine a HARQ configuration for a second TTI, and the second TTI may carry HARQ information responsive to a transmission in a third TTI, wherein the third TTI has a third duration that is less than the first duration. The HARQ configuration may change the direction of transmission for the second TTI. Determining the HARQ configuration may include identifying a plurality of reference HARQ configurations and selecting a HARQ configuration from the plurality of reference HARQ configurations. The TDD mode manager 1325 may select the HARQ configuration for the second TTI based at least in part on a value of a parameter of the identified channel.

[0133] In some cases, the TDD mode manager 1325 may identify a HARQ timing offset for the second TTI. The HARQ configuration indicator may identify the HARQ timing offset. Identifying the HARQ timing offset may include identifying a value of a parameter associated with the HARQ process, and identifying the HARQ timing offset for the second TTI based at least in part on the value of the parameter of the identified channel. The parameter associated with the HARQ process may be or include downlink load, uplink load, interference pattern, downlink processing time, uplink processing time, or a combination thereof.

[0134] The TDD mode indicator component 1330 can transmit a TDD mode indicator in the first control region or the second control region, identifying the determined TDD mode for the second TTI. The TDD mode indicator component 1330 can transmit the TDD mode indicator in a first grant of resources received in a first control message, in a second grant of resources received in a second control message, or in a common search space in the control region for the first TTI, or any combination thereof.

[0135] In some cases, the TDD mode indicator component 1330 may transmit a HARQ configuration indicator in the first control region or the second control region, identifying the determined HARQ configuration for the second TTI. In some cases, transmitting the HARQ configuration indicator includes transmitting an indication of an entry in an association table. The association table may indicate a temporal relationship between a TTI used to transmit the HARQ information and a TTI to which the TTI used to transmit the HARQ information responds.

[0136] The default TDD mode identifier 1335 may identify the default TDD mode associated with the second TTI. The determined TDD mode may change the transmission direction for at least a portion of the default TDD mode. The transmission direction identifier 1340 may identify the transmission direction associated with the first TTI during at least a portion of the second duration and identify the transmission direction associated with the time interval adjacent to the second TTI.

[0137] The guard period manager 1345 may determine the location and duration of the guard period for the second TTI based on the identified transmission direction associated with the time interval adjacent to the second TTI. In some cases, the guard period manager 1345 may identify a symbol period of a reference signal for the TDD mode of the first TTI. In such a case, the guard period manager 1345 may also determine the location of one or more guard periods based at least in part on the identified symbol period of the reference signal. The reference signal may be or include a CRS or a DMRS.

[0138] In some cases, the guard period manager 1345 may identify a boundary of a symbol period of the TDD mode for the first TTI. In such a case, the guard period manager 1345 may determine a position of a guard period in one or more guard periods based at least in part on the identified boundary. Determining the position of the guard period may include aligning the boundary of the guard period with the identified boundary of the symbol period.

[0139] In some cases, the guard period manager 1345 may identify a transmission type associated with the first TTI. In such cases, the guard period manager 1345 may also identify a location of one or more guard periods for the TDD mode within the second TTI based at least in part on the identified transmission direction associated with the first TTI. The identified transmission type associated with the first TTI may be an uplink transmission, a downlink transmission, or an MBSFN transmission.

[0140] In some examples, guard period manager 1345 may identify a slot index associated with the first TTI. In some examples, guard period manager 1345 may also identify locations of one or more guard periods of the TDD mode based at least in part on the slot index associated with the first TTI.

[0141] The reference signal manager 1350 may identify a conflict between the second TTI and the first reference signal pattern of one or more reference signals associated with the first TTI. The reference signal manager 1350 may send one or more reference signals according to the second reference signal pattern. In some cases, the reference signal manager 1350 may send an indication of the second reference signal pattern in the first control region.

[0142] Figure 14 According to various aspects of the present disclosure, a diagram of a system 1400 is shown that includes a device 1405 that supports dynamic TDD. The device 1405 can be as described above, for example, with reference to Figure 114. The example of a base station 105 described herein may include components of a base station 105. Device 1405 may include components for two-way voice and data communications, including components for sending communications and components for receiving communications, including a base station communications manager 1415, a processor 1420, memory 1425, software 1430, a transceiver 1435, an antenna 1440, a network communications manager 1445, and a base station communications manager 1450. These components may communicate electronically via one or more buses, such as bus 1410. Device 1405 may communicate wirelessly with one or more UEs 115.

[0143] The base station communication manager 1415 can manage communications with other base stations 105 and can include a controller or scheduler for controlling communications with the UE 115 in cooperation with the other base stations 105. For example, the base station communication manager 1415 can coordinate the scheduling of transmissions to the UE 115 to implement various interference mitigation techniques such as beamforming or joint transmission. In some examples, the base station communication manager 1415 can provide an X2 interface in a long-term evolution (LTE) / LTE-A wireless communication network technology to provide communications between base stations 105.

[0144] The processor 1420 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, the processor 1420 may be configured to operate the memory array using a memory controller. In other cases, the memory controller may be integrated into the processor 1420. The processor 1420 may be configured to execute computer-readable instructions stored in the memory to perform various functions (e.g., functions or tasks for supporting dynamic TDD).

[0145] Memory 1425 may include RAM and ROM. Memory 1425 may store computer-readable, computer-executable software 1430 that includes instructions that, when executed, cause the processor to perform the various functions described herein. In some cases, memory 1425 may also contain, among other things, a BIOS that may control basic hardware and / or software operations, such as interaction with peripheral components or devices.

[0146] The software 1430 may include code for implementing aspects of the present disclosure, including code for supporting dynamic TDD. The software 1430 may be stored in a non-transitory computer-readable medium (such as system memory or other memory). In some cases, the software 1430 may not be directly executable by a processor, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

[0147] The transceiver 1435 can communicate bidirectionally via one or more antennas, wired or wireless links, as described above. For example, the transceiver 1435 can represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver. The transceiver 1435 can also include a modem for modulating packets and providing the modulated packets to the antenna for transmission, and demodulating packets received from the antenna. In some cases, the wireless device can include a single antenna 1440. However, in some cases, the device can have more than one antenna 1440, which can simultaneously send or receive multiple wireless transmissions.

[0148] The network communications manager 1445 may manage communications with the core network (eg, via one or more wired backhaul links). For example, the network communications manager 1445 may manage the transmission of data communications for client devices, such as one or more UEs 115.

[0149] Figure 15 According to various aspects of the present disclosure, a flow chart illustrating a method 1500 for dynamic TDD is shown. The operations of the method 1500 may be implemented by the UE 115 or its components as described herein. For example, the operations of the method 1500 may be performed by the UE communication manager, as described with reference to FIG. Figures 7 to 10 In some examples, the UE 115 may execute a code set to control functional elements of the device to perform the functions described below. Additionally or alternatively, the UE 115 may use dedicated hardware to perform aspects of the functions described below.

[0150] At block 1505, UE 115 may receive a first control message within a first control region having a first TTI of a first duration. Figures 1 to 6 The method described herein performs the operations of block 1505. In some examples, aspects of the operations of block 1505 can be performed by a control message component, as described with reference to Figures 7 to 10 Descriptive.

[0151] At block 1510, the UE 115 may receive a second control message within a second control region of a second TTI having a second duration that is less than the first duration. Figures 1 to 6The method described herein performs the operations of block 1510. In some examples, aspects of the operations of block 1510 may be performed by a control message component, as described with reference to Figures 7 to 10 Descriptive.

[0152] At block 1515, the UE 115 may receive a TDD mode indicator for the second TTI in the first control region or the second control region. Figures 1 to 6 The method described herein performs the operations of block 1515. In some examples, aspects of the operations of block 1515 may be performed by a TDD mode indicator component, as described with reference to Figures 7 to 10 Descriptive.

[0153] At block 1520, the UE 115 may determine a TDD mode for the second TTI based at least in part on the received TDD mode indicator, wherein the TDD mode changes the transmission direction for the second TTI. Figures 1 to 6 The method described herein performs the operations of block 1520. In some examples, aspects of the operations of block 1520 may be performed by a TDD mode manager component, as described with reference to Figures 7 to 10 Descriptive.

[0154] Figure 16 According to various aspects of the present disclosure, a flow chart illustrating a method 1600 for dynamic TDD is shown. The operations of the method 1600 may be implemented by the base station 105 or components thereof, as described herein. For example, the operations of the method 1600 may be performed by a base station communication manager, as described with reference to Figures 11 to 14 In some examples, the base station 105 may execute a code set to control functional elements of the device to perform the functions described below. Additionally or alternatively, the base station 105 may use dedicated hardware to perform aspects of the functions described below.

[0155] At block 1605, the base station 105 may send a first control message within a first control region having a first TTI of a first duration. Figures 1 to 6 The method described herein performs the operations of block 1605. In some examples, aspects of the operations of block 1605 can be performed by a control message component, as described with reference to Figures 11 to 14 Descriptive.

[0156] At block 1610, the base station 105 may send a second control message within a second control region of a second TTI having a second duration that is less than the first duration. Figures 1 to 6 The method described herein performs the operations of block 1610. In some examples, aspects of the operations of block 1610 may be performed by a control message component, as described with reference to Figures 11 to 14 Descriptive.

[0157] At block 1615, the base station 105 may determine a TDD mode for the second TTI, wherein the TDD mode changes the transmission direction for the second TTI. Figures 1 to 6 The method described herein performs the operations of block 1615. In some examples, aspects of the operations of block 1615 may be performed by a TDD mode manager, as described with reference to Figures 11 to 14 Descriptive.

[0158] At block 1620, the base station 105 may send a TDD mode indicator in the first control region or the second control region, which is used to identify the determined TDD mode for the second TTI. Figures 1 to 6 The method described herein performs the operations of block 1620. In some examples, aspects of the operations of block 1620 may be performed by a TDD mode indicator component, as described with reference to Figures 11 to 14 Descriptive.

[0159] Figure 17 According to various aspects of the present disclosure, a flow chart illustrating a method 1700 for dynamic TDD is shown. The operations of the method 1700 may be implemented by the base station 105 or components thereof, as described herein. For example, the operations of the method 1700 may be performed by a base station communication manager, as described with reference to Figures 11 to 14 In some examples, the base station 105 may execute a code set to control functional elements of the device to perform the functions described below. Additionally or alternatively, the base station 105 may use dedicated hardware to perform aspects of the functions described below.

[0160] At block 1705, the base station 105 may send a first control message within a first control region having a first TTI of a first duration. Figures 1 to 6 The method described herein performs the operations of block 1705. In some examples, aspects of the operations of block 1705 can be performed by a control message component, as described with reference to Figures 11 to 14 Descriptive.

[0161] At block 1710, the base station 105 may send a second control message within a second control region of a second TTI having a second duration that is less than the first duration. Figures 1 to 6 The method described herein performs the operations of block 1710. In some examples, aspects of the operations of block 1710 may be performed by a control message component, as described with reference to Figures 11 to 14 Descriptive.

[0162] At block 1715, the base station 105 may identify a default TDD mode associated with the second TTI. Figures 1 to 6The method described herein performs the operations of block 1715. In some examples, aspects of the operations of block 1715 can be performed by a default TDD pattern recognizer, as described with reference to Figures 11 to 14 Descriptive.

[0163] At block 1720, the base station 105 may determine a TDD mode for the second TTI, wherein the TDD mode changes the transmission direction for the default TDD mode associated with the second TTI. Figures 1 to 6 The methods described herein perform the operations of block 1720. In some examples, aspects of the operations of block 1720 may be performed by a TDD mode manager, as described with reference to Figures 11 to 14 Descriptive.

[0164] At block 1725, the base station 105 may send a TDD mode indicator in the first control region or the second control region, which is used to identify the determined TDD mode for the second TTI. Figures 1 to 6 The method described herein performs the operations of block 1725. In some examples, aspects of the operations of block 1725 may be performed by a TDD mode indicator component, as described with reference to Figures 11 to 14 Descriptive.

[0165] Figure 18 According to various aspects of the present disclosure, a flow chart illustrating a method 1800 for dynamic TDD is shown. The operations of the method 1800 may be implemented by the base station 105 or components thereof, as described herein. For example, the operations of the method 1800 may be performed by a base station communication manager, as described with reference to Figures 11 to 14 In some examples, the base station 105 may execute a code set to control functional elements of the device to perform the functions described below. Additionally or alternatively, the base station 105 may use dedicated hardware to perform aspects of the functions described below.

[0166] At block 1805, the base station 105 may send a first control message within a first control region having a first TTI of a first duration. Figures 1 to 6 The method described herein performs the operations of block 1805. In some examples, aspects of the operations of block 1805 can be performed by a control message component, as described with reference to Figures 11 to 14 Descriptive.

[0167] At block 1810, the base station 105 may send a second control message within a second control region of a second TTI having a second duration that is less than the first duration. Figures 1 to 6 The method described herein performs the operations of block 1810. In some examples, aspects of the operations of block 1810 may be performed by a control message component, as described with reference to Figures 11 to 14 Descriptive.

[0168] At block 1815, the base station 105 may identify a transmission direction associated with a time interval adjacent to the second TTI. Figures 1 to 6 The method described herein performs the operations of block 1815. In some examples, aspects of the operations of block 1815 may be performed by a transmission direction identifier, as described with reference to Figures 11 to 14 Descriptive.

[0169] At block 1820, the base station 105 may determine a TDD mode for the second TTI based on the identified transmission direction associated with the time interval adjacent to the second TTI, wherein the TDD mode changes the transmission direction for the second TTI. Figures 1 to 6 The method described herein performs the operations of block 1820. In some examples, aspects of the operations of block 1820 may be performed by a TDD mode manager, as described with reference to Figures 11 to 14 Descriptive.

[0170] At block 1825, the base station 105 may determine the location and duration of the guard period for the second TTI based on the identified transmission direction associated with the time interval adjacent to the second TTI. Figures 1 to 6 The method described herein performs the operations of block 1825. In some examples, aspects of the operations of block 1825 may be performed by a protection period manager, as described with reference to Figures 11 to 14 Descriptive.

[0171] At block 1830, the base station 105 may send a TDD mode indicator in the first control region or the second control region, which is used to identify the determined TDD mode for the second TTI. Figures 1 to 6 The method described herein performs the operations of block 1830. In some examples, aspects of the operations of block 1830 may be performed by a TDD mode indicator component, as described with reference to Figures 11 to 14 Descriptive.

[0172] Figure 19 According to various aspects of the present disclosure, a flow chart illustrating a method 1900 for dynamic TDD is shown. The operations of the method 1900 may be implemented by the base station 105 or components thereof, as described herein. For example, the operations of the method 1900 may be performed by a base station communication manager, as described with reference to Figures 11 to 14 In some examples, the base station 105 may execute a code set to control functional elements of the device to perform the functions described below. Additionally or alternatively, the base station 105 may use dedicated hardware to perform aspects of the functions described below.

[0173] At block 1905, the base station 105 may send a first control message within a first control region having a first TTI of a first duration. Figures 1 to 6 The method described herein performs the operations of block 1905. In some examples, aspects of the operations of block 1905 can be performed by a control message component, as described with reference to Figures 11 to 14 Descriptive.

[0174] At block 1910, the base station 105 may send a second control message within a second control region of a second TTI having a second duration that is less than the first duration. Figures 1 to 6 The method described herein performs the operations of block 1910. In some examples, aspects of the operations of block 1910 may be performed by a control message component, as described with reference to Figures 11 to 14 Descriptive.

[0175] At block 1915, the base station 105 may determine a TDD mode for the second TTI, wherein the TDD mode changes the transmission direction for the second TTI. Figures 1 to 6 The method described herein performs the operations of block 1915. In some examples, aspects of the operations of block 1915 may be performed by a TDD mode manager, as described with reference to Figures 11 to 14 Descriptive.

[0176] At block 1920, the base station 105 may send a TDD mode indicator in the first control region or the second control region, which is used to identify the determined TDD mode for the second TTI. Figures 1 to 6 The method described herein performs the operations of block 1920. In some examples, aspects of the operations of block 1920 may be performed by a TDD mode indicator component, as described with reference to Figures 11 to 14 Descriptive.

[0177] At block 1925, the base station 105 may identify a conflict between the second TTI and the first reference signal pattern of one or more reference signals associated with the first TTI. Figures 1 to 6 The method described herein performs the operations of block 1925. In some examples, aspects of the operations of block 1925 may be performed by a reference signal manager, such as a reference signal manager. Figures 11 to 14 Descriptive.

[0178] At block 1930, the base station 105 may transmit one or more reference signals according to a second reference signal pattern. Figures 1 to 6 The method described herein performs the operations of block 1930. In some examples, aspects of the operations of block 1930 may be performed by a reference signal manager, such as a reference signal manager. Figures 11 to 14 Descriptive.

[0179] At block 1935, the base station 105 may send an indication of a second reference signal pattern in the first control region. Figures 1 to 6 The method described herein performs the operations of block 1935. In some examples, aspects of the operations of block 1935 may be performed by a reference signal manager, such as a reference signal manager. Figures 11 to 14 Descriptive.

[0180] Figure 20 According to various aspects of the present disclosure, a flow chart illustrating a method 2000 for dynamic TDD is shown. The operations of the method 2000 may be implemented by the UE 115 or its components as described herein. For example, the operations of the method 2000 may be performed by the UE communication manager, as described with reference to FIG. Figures 7 to 10 In some examples, the UE 115 may execute a code set to control functional elements of the device to perform the functions described below. Additionally or alternatively, the UE 115 may use dedicated hardware to perform aspects of the functions described below.

[0181] At block 2005, UE 115 may receive a first control message within a first control region having a first TTI of a first duration. Figures 1 to 6 The method described herein performs the operations of block 2005. In some examples, aspects of the operations of block 2005 may be performed by a control message component, as described with reference to Figures 7 to 10 Descriptive.

[0182] At block 2010, the UE 115 may receive a second control message within a second control region of a second TTI having a second duration that is less than the first duration. Figures 1 to 6 The method described herein performs the operations of block 2010. In some examples, aspects of the operations of block 2010 may be performed by a control message component, as described with reference to Figures 7 to 10 Descriptive.

[0183] At block 2015, the UE 115 may receive a TDD mode indicator for a second TTI in the first control region or the second control region. Figures 1 to 6 In some examples, aspects of the operations of block 2015 may be performed by a TDD mode indicator component, as described with reference to Figures 7 to 10 Descriptive.

[0184] At block 2020, the UE 115 may determine, based at least in part on the TDD mode indicator, one or more guard periods for the TDD mode for the second TTI, wherein a first guard period of the one or more guard periods is located between a first portion of the TDD mode having a first transmission direction and a second portion of the TDD mode having a second transmission direction different from the first transmission direction. Figures 1 to 6 The method described herein performs the operations of block 2020. In some examples, aspects of the operations of block 2020 may be performed by a TDD mode manager, as described with reference to Figures 7 to 10 Descriptive.

[0185] Figure 21 According to various aspects of the present disclosure, a flow chart illustrating a method 2100 for dynamic TDD is shown. The operations of the method 2100 may be implemented by the base station 105 or its components as described herein. For example, the operations of the method 2100 may be performed by a base station communication manager, as described with reference to Figures 11 to 14 In some examples, the base station 105 may execute a code set to control functional elements of the device to perform the functions described below. Additionally or alternatively, the base station 105 may use dedicated hardware to perform aspects of the functions described below.

[0186] At block 2105, the base station 105 may send a first control message within a first control region having a first TTI of a first duration. Figures 1 to 6 The method described herein performs the operations of block 2105. In some examples, aspects of the operations of block 2105 can be performed by a control message component, as described with reference to Figures 11 to 14 Descriptive.

[0187] At block 2110, the base station 105 may send a second control message within a second control region of a second TTI having a second duration that is less than the first duration. Figures 1 to 6 The method described herein performs the operations of block 2110. In some examples, aspects of the operations of block 2110 may be performed by a control message component, as described with reference to Figures 11 to 14 Descriptive.

[0188] At block 2115, the base station 105 may determine a TDD mode for the second TTI. The TDD mode may include one or more guard periods for the second TTI. A first guard period in the one or more guard periods may be located between a first portion of the TDD mode having a first transmission direction and a second portion of the TDD mode having a second transmission direction different from the first transmission direction. Figures 1 to 6The method described herein performs the operations of block 2115. In some examples, aspects of the operations of block 2115 may be performed by a TDD mode manager, as described with reference to Figures 11 to 14 Descriptive.

[0189] At block 2120, the base station 105 may send a TDD mode indicator in the first control region or the second control region, which is used to identify the determined TDD mode for the second TTI. Figures 1 to 6 The method described herein performs the operations of block 2120. In some examples, aspects of the operations of block 2120 may be performed by a TDD mode indicator component, as described with reference to Figures 11 to 14 Descriptive.

[0190] Figure 22 According to various aspects of the present disclosure, a flow chart illustrating a method 2200 for dynamic TDD is shown. The operations of the method 2200 may be implemented by the UE 115 or its components as described herein. For example, the operations of the method 2200 may be performed by the UE communication manager, as described with reference to FIG. Figures 7 to 10 In some examples, the UE 115 may execute a code set to control functional elements of the device to perform the functions described below. Additionally or alternatively, the UE 115 may use dedicated hardware to perform aspects of the functions described below.

[0191] At block 2205, UE 115 may receive a first control message within a first control region having a first TTI of a first duration. Figures 1 to 6 The method described herein performs the operations of block 2205. In some examples, aspects of the operations of block 2205 can be performed by a control message component, as described with reference to Figures 7 to 10 Descriptive.

[0192] At block 2210, the UE 115 may receive a second control message within a second control region of a second TTI having a second duration that is less than the first duration. Figures 1 to 6 The method described herein performs the operations of block 2210. In some examples, aspects of the operations of block 2210 may be performed by a control message component, as described with reference to Figures 7 to 10 Descriptive.

[0193] At block 2215, the UE 115 may receive a HARQ configuration indicator for the second TTI in the first control region or the second control region. Figures 1 to 6 The method described herein performs the operations of block 2215. In some examples, aspects of the operations of block 2215 may be performed by a TDD mode indicator component, as described with reference to Figures 7 to 10 Descriptive.

[0194] At block 2220, the UE 115 may determine a HARQ configuration for a second TTI based at least in part on the received HARQ configuration indicator. The second TTI may carry HARQ information responsive to a transmission in a third TTI, wherein the third TTI has a third duration that is less than the first duration. And the HARQ configuration may change the direction of transmission for the second TTI. The HARQ configuration may be based on the reference Figures 1 to 6 The methods described herein perform the operations of block 2220. In some examples, aspects of the operations of block 2220 may be performed by a TDD mode manager component, as described with reference to Figures 7 to 10 Descriptive.

[0195] Figure 23 According to various aspects of the present disclosure, a flow chart illustrating a method 2300 for dynamic TDD is shown. The operations of the method 2300 may be implemented by the base station 105 or its components as described herein. For example, the operations of the method 2300 may be performed by a base station communication manager, as described with reference to Figures 11 to 14 In some examples, the base station 105 may execute a code set to control functional elements of the device to perform the functions described below. Additionally or alternatively, the base station 105 may use dedicated hardware to perform aspects of the functions described below.

[0196] At block 2305, the base station 105 may send a first control message within a first control region having a first TTI of a first duration. Figures 1 to 6 The method described herein performs the operations of block 2305. In some examples, aspects of the operations of block 2305 can be performed by a control message component, as described with reference to Figures 11 to 14 Descriptive.

[0197] At block 2310, the base station 105 may send a second control message within a second control region of a second TTI having a second duration that is less than the first duration. Figures 1 to 6 The method described herein performs the operations of block 2310. In some examples, aspects of the operations of block 2310 can be performed by a control message component, such as with reference to Figures 11 to 14 Descriptive.

[0198] At block 2315, the base station 105 may determine a HARQ configuration for a second TTI, wherein the second TTI is used to carry HARQ information in response to a transmission in a third TTI, wherein the third TTI has a third duration that is less than the first duration. The HARQ configuration may change the direction of transmission for the second TTI. Figures 1 to 6The method described herein performs the operations of block 2315. In some examples, aspects of the operations of block 2315 may be performed by a TDD mode manager, as described with reference to Figures 11 to 14 Descriptive.

[0199] At block 2320, the base station 105 may send a HARQ configuration indicator in the first control region or the second control region, which is used to identify the determined HARQ configuration for the second TTI. Figures 1 to 6 The method described herein performs the operations of block 2320. In some examples, aspects of the operations of block 2320 may be performed by a TDD mode indicator component, as described with reference to Figures 11 to 14 Descriptive.

[0200] An apparatus for wireless communication is described. The apparatus may include: means for receiving a first control message within a first control region within a first TTI having a first duration; means for receiving a second control message within a second control region within a second TTI having a second duration less than the first duration; means for receiving a TDD mode indicator for the second TTI in the first control region or the second control region; and means for determining a TDD mode for the second TTI based at least in part on the received TDD mode indicator, wherein the TDD mode changes a transmission direction for the second TTI.

[0201] A non-transitory computer-readable medium for wireless communication is described. The non-transitory computer-readable medium may include instructions operable to cause a processor to: receive a first control message within a first control region of a first TTI having a first duration; receive a second control message within a second control region of a second TTI having a second duration less than the first duration; receive a TDD mode indicator for the second TTI in the first control region or the second control region; and determine a TDD mode for the second TTI based at least in part on the received TDD mode indicator, wherein the TDD mode changes a transmission direction for the second TTI.

[0202] Some examples of the methods, apparatus, and non-transitory computer-readable media described above may also include processes, features, units, or instructions for identifying a default TDD mode associated with a second TTI, wherein the determined TDD mode changes a transmission direction for at least a portion of the default TDD mode.

[0203] In some examples of the methods, apparatus, and non-transitory computer-readable media described above, determining the TDD mode for the second TTI includes selecting a TDD mode from a plurality of predetermined TDD modes based at least in part on the received TDD mode indicator.

[0204] In some examples of the methods, apparatuses, and non-transitory computer-readable media described above, selecting a TDD mode from a plurality of predetermined TDD modes includes reading a table comprising a plurality of TDD mode indicator entries associated with respective TDD modes. Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may also include a process, feature, unit, or instruction for selecting a TDD mode for a second TTI that may be associated with a TDD mode indicator entry corresponding to the received TDD mode indicator.

[0205] Some examples of the methods, apparatus, and non-transitory computer-readable media described above may also include processes, features, units, or instructions for identifying that the determined TDD mode applies to a predetermined number of TTIs, including a second TTI that may have a second duration.

[0206] In some examples of the methods, apparatus, and non-transitory computer-readable media described above, the TDD mode indicator may be included in at least one of: a first grant of resources received in a first control message, or a second grant of resources received in a second control message, or a common search space in a first control region of a first TTI, or any combination thereof.

[0207] In some examples of the methods, apparatus, and non-transitory computer-readable media described above, the second duration of the second TTI includes an integer number of symbol periods or one time slot.

[0208] In some examples of the methods, apparatus, and non-transitory computer-readable media described above, the first TTI and the second TTI at least partially overlap in time.

[0209] An apparatus for wireless communication is described. The apparatus may include: means for sending a first control message within a first control region having a first duration; means for sending a second control message within a second control region having a second duration less than the first duration; means for determining a TDD mode for the second TTI, wherein the TDD mode changes a transmission direction for the second TTI; and means for sending a TDD mode indicator in the first control region or the second control region, the TDD mode indicator identifying the determined TDD mode for the second TTI.

[0210] A non-transitory computer-readable medium for wireless communication is described. The non-transitory computer-readable medium may include instructions operable to cause a processor to: send a first control message within a first control region of a first time interval (TTI) having a first duration; send a second control message within a second control region of a second time interval (TTI) having a second duration less than the first duration; determine a time delay (TDD) mode for the second TTI, wherein the TDD mode changes a transmission direction for the second TTI; and send a TDD mode indicator in the first control region or the second control region, the TDD mode indicator identifying the determined TDD mode for the second TTI.

[0211] Some examples of the methods, apparatus, and non-transitory computer-readable media described above may also include processes, features, units, or instructions for identifying a default TDD mode associated with a second TTI, wherein the determined TDD mode changes a transmission direction for at least a portion of the default TDD mode.

[0212] Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may further include a process, feature, unit, or instruction for identifying a transmission direction associated with the first TTI during at least a portion of the second duration. Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may further include a process, feature, unit, or instruction for determining a TDD mode for the second TTI based at least in part on the identified transmission direction.

[0213] Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may further include a process, feature, unit, or instruction for identifying a transmission direction associated with a time interval preceding a second TTI. Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may further include a process, feature, unit, or instruction for determining a TDD mode for a second TTI based at least in part on the identified transmission direction associated with the time interval preceding the second TTI.

[0214] Some examples of the methods, apparatus, and non-transitory computer-readable media described above may also include processes, features, units, or instructions for determining a location and duration of a guard period for a second TTI based at least in part on an identified transmission direction associated with a time interval adjacent to the second TTI.

[0215] In some examples of the methods, apparatus, and non-transitory computer-readable media described above, the TDD mode for the second TTI includes at least one of: downlink resources, or uplink resources, or one or more guard periods, or any combination thereof.

[0216] Some examples of the methods, apparatus, and non-transitory computer-readable media described above may also include processes, features, units, or instructions for performing the following operations: sending a TDD mode indicator in at least one of the following: a first grant of resources received in a first control message, or a second grant of resources received in a second control message, or a common search space in a first control region of a first TTI, or any combination thereof.

[0217] Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may also include a process, feature, unit, or instruction for identifying a conflict between a second TTI and a first reference signal pattern of one or more reference signals associated with the first TTI. Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may also include a process, feature, unit, or instruction for transmitting one or more reference signals according to the second reference signal pattern. Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may also include a process, feature, unit, or instruction for transmitting an indication of the second reference signal pattern in the first control region.

[0218] A method of wireless communication is described. The method may include: sending a first control message within a first control region having a first time interval (TTI) having a first duration; sending a second control message within a second control region having a second time interval (TTI) having a second duration less than the first duration; determining a hybrid automatic repeat request (HARQ) configuration for the second TTI, the second TTI being used to carry HARQ information in response to a transmission in a third TTI, the third TTI having a third duration less than the first duration, wherein the HARQ configuration changes a transmission direction for the second TTI; and sending a HARQ configuration indicator within the first control region or the second control region, the HARQ configuration indicator identifying the determined HARQ configuration for the second TTI.

[0219] An apparatus for wireless communication is described. The apparatus may include: means for sending a first control message within a first control region having a first time interval (TTI) having a first duration; means for sending a second control message within a second control region having a second time interval (TTI) having a second duration less than the first duration; means for determining a HARQ configuration for the second TTI, the second TTI being used to carry HARQ information responsive to a transmission in a third TTI, the third TTI having a third duration less than the first duration, wherein the HARQ configuration changes a transmission direction for the second TTI; and means for sending a HARQ configuration indicator within the first control region or the second control region, the HARQ configuration indicator identifying the determined HARQ configuration for the second TTI.

[0220] Another apparatus for wireless communication is described. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. The instructions are operable to cause the processor to: send a first control message within a first control region having a first duration; send a second control message within a second control region having a second duration less than the first duration; determine a HARQ configuration for the second TTI, the second TTI being used to carry HARQ information in response to a transmission in a third TTI, wherein the third TTI has a third duration less than the first duration, wherein the HARQ configuration changes a transmission direction for the second TTI; and send a HARQ configuration indicator within the first control region or the second control region, the HARQ configuration indicator being used to identify the determined HARQ configuration for the second TTI.

[0221] A non-transitory computer-readable medium for wireless communication is described. The non-transitory computer-readable medium may include instructions operable to cause a processor to: send a first control message within a first control region having a first duration; send a second control message within a second control region having a second duration less than the first duration; determine a HARQ configuration for the second TTI, the second TTI being used to carry HARQ information responsive to a transmission in a third TTI, the third TTI having a third duration less than the first duration, wherein the HARQ configuration changes a transmission direction for the second TTI; and send a HARQ configuration indicator within the first control region or the second control region, the HARQ configuration indicator identifying the determined HARQ configuration for the second TTI.

[0222] In some examples of the methods, apparatuses, and non-transitory computer-readable media described above, determining the HARQ configuration for the second TTI may include identifying a plurality of reference HARQ configurations. Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may also include a process, feature, unit, or instruction for selecting a HARQ configuration from the plurality of reference HARQ configurations.

[0223] Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may also include a process, feature, unit, or instruction for identifying a value of a parameter of a channel used to transmit the first control message and the second control message. Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may also include a process, feature, unit, or instruction for selecting a HARQ configuration for the second TTI based at least in part on the value of the parameter of the identified channel.

[0224] In some examples of the methods, apparatus, and non-transitory computer-readable media described above, the parameter of the channel includes a length of the second TTI, or an acknowledgment transmission delay, or a downlink load, or an uplink load, or a combination thereof.

[0225] Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may also include processes, features, units, or instructions for performing the following operations: identifying a HARQ timing offset for a second TTI, the HARQ configuration indicator being used to identify the HARQ timing offset.

[0226] In some examples of the methods, apparatuses, and non-transitory computer-readable media described above, identifying the HARQ timing offset includes identifying a value of a parameter associated with the HARQ process. Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may also include a process, feature, means, or instructions for identifying the HARQ timing offset for the second TTI based at least in part on the value of the parameter of the identified channel.

[0227] In some examples of the methods, apparatus, and non-transitory computer-readable media described above, parameters associated with the HARQ process include downlink load, or uplink load, or interference pattern, or downlink processing time, or uplink processing time, or a combination thereof.

[0228] In some examples of the methods, apparatus, and non-transitory computer-readable media described above, sending the HARQ configuration indicator includes sending an indication of an entry in an association table that indicates a temporal relationship between a TTI for transmitting HARQ information and a TTI to which the TTI for transmitting the HARQ information can respond.

[0229] A method of wireless communication is described. The method may include receiving a first control message within a first control region of a first TTI having a first duration; receiving a second control message within a second control region of a second TTI having a second duration less than the first duration; receiving a HARQ configuration indicator for the second TTI in the first control region or the second control region; and determining a HARQ configuration for a second TTI based at least in part on the received HARQ configuration indicator, the second TTI being used to carry HARQ information responsive to a transmission in a third TTI, the third TTI having a third duration less than the first duration, wherein the HARQ configuration changes a transmission direction for the second TTI.

[0230] An apparatus for wireless communication is described. The apparatus may include: means for receiving a first control message within a first control region having a first time interval (TTI) having a first duration; means for receiving a second control message within a second control region having a second time interval (TTI) having a second duration less than the first duration; means for receiving a HARQ configuration indicator for a second TTI in the first control region or the second control region; and means for determining a HARQ configuration for the second TTI based at least in part on the received HARQ configuration indicator, the second TTI being used to carry HARQ information responsive to a transmission in a third TTI having a third duration less than the first duration, wherein the HARQ configuration changes a transmission direction for the second TTI.

[0231] Another apparatus for wireless communication is described. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. The instructions are operable to cause the processor to: receive a first control message within a first control region having a first duration; receive a second control message within a second control region having a second duration less than the first duration; receive a HARQ configuration indicator for the second TTI in the first control region or the second control region; and determine a HARQ configuration for the second TTI based at least in part on the received HARQ configuration indicator, the second TTI being used to carry HARQ information responsive to a transmission in a third TTI, wherein the third TTI has a third duration less than the first duration, wherein the HARQ configuration changes a transmission direction for the second TTI.

[0232] A non-transitory computer-readable medium for wireless communication is described. The non-transitory computer-readable medium may include instructions operable to cause a processor to: receive a first control message within a first control region of a first TTI having a first duration; receive a second control message within a second control region of a second TTI having a second duration less than the first duration; receive a HARQ configuration indicator for the second TTI in the first control region or the second control region; and determine, based at least in part on the received HARQ configuration indicator, a HARQ configuration for the second TTI, the second TTI being used to carry HARQ information responsive to a transmission in a third TTI, the third TTI having a third duration less than the first duration, wherein the HARQ configuration changes a transmission direction for the second TTI.

[0233] In some examples of the methods, apparatuses, and non-transitory computer-readable media described above, determining the HARQ configuration includes identifying a plurality of reference HARQ configurations. Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may also include a process, feature, means, or instruction for selecting a HARQ configuration from the plurality of reference HARQ configurations.

[0234] Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may also include a process, feature, unit, or instruction for identifying a value of a parameter of a channel for receiving the first control message and the second control message. Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may also include a process, feature, unit, or instruction for selecting a HARQ configuration for the second TTI based at least in part on the value of the parameter of the identified channel.

[0235] In some examples of the methods, apparatus, and non-transitory computer-readable media described above, the parameter of the channel includes a length of the second TTI, or an acknowledgment transmission delay, or a downlink load, or an uplink load, or a combination thereof.

[0236] Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may also include processes, features, units, or instructions for performing the following operations: identifying a HARQ timing offset for a second TTI, the HARQ configuration indicator being used to identify the HARQ timing offset.

[0237] In some examples of the methods, apparatuses, and non-transitory computer-readable media described above, identifying the HARQ timing offset includes identifying a value of a parameter associated with the HARQ process. Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may also include a process, feature, means, or instructions for identifying the HARQ timing offset for the second TTI based at least in part on the value of the parameter of the identified channel.

[0238] In some examples of the methods, apparatus, and non-transitory computer-readable media described above, parameters associated with the HARQ process include downlink load, or uplink load, or interference pattern, or downlink processing time, or uplink processing time, or a combination thereof.

[0239] In some examples of the methods, apparatus, and non-transitory computer-readable media described above, receiving the HARQ configuration indicator includes receiving an indication of an entry in an association table that indicates a temporal relationship between a TTI for transmitting HARQ information and a TTI to which the TTI for transmitting the HARQ information can respond.

[0240] A method of wireless communication is described. The method may include: sending a first control message within a first control region having a first duration, sending a second control message within a second control region having a second duration that is less than the first duration, determining a TDD mode for the second TTI, the TDD mode including one or more guard periods of the second TTI, a first guard period of the one or more guard periods being located between a first portion of the TDD mode having a first transmission direction and a second portion of the TDD mode having a second transmission direction different from the first transmission direction, and sending a TDD mode indicator within the first control region or the second control region, the TDD mode indicator being used to identify the determined TDD mode for the second TTI.

[0241] An apparatus for wireless communication is described. The apparatus may include: means for sending a first control message within a first control region having a first duration, a means for sending a second control message within a second control region having a second duration that is smaller than the first duration, means for determining a TDD mode for the second TTI, the TDD mode comprising one or more guard periods of the second TTI, a first guard period of the one or more guard periods being positioned between a first portion of the TDD mode having a first transmission direction and a second portion of the TDD mode having a second transmission direction different from the first transmission direction, and means for sending a TDD mode indicator within the first control region or the second control region, the TDD mode indicator being used to identify the determined TDD mode for the second TTI.

[0242] Another apparatus for wireless communication is described. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. The instructions are operable to cause the processor to perform the following operations: send a first control message within a first control region having a first duration; send a second control message within a second control region having a second duration less than the first duration; determine a TDD mode for the second TTI, the TDD mode including one or more guard periods of the second TTI, a first guard period of the one or more guard periods being located between a first portion of the TDD mode having a first transmission direction and a second portion of the TDD mode having a second transmission direction different from the first transmission direction; and send a TDD mode indicator within the first control region or the second control region, the TDD mode indicator being used to identify the determined TDD mode for the second TTI.

[0243] A non-transitory computer-readable medium for wireless communication is described. The non-transitory computer-readable medium may include instructions operable to cause a processor to: send a first control message within a first control region having a first duration; send a second control message within a second control region having a second duration less than the first duration; determine a TDD mode for the second TTI, the TDD mode including one or more guard periods of the second TTI, a first guard period of the one or more guard periods being located between a first portion of the TDD mode having a first transmission direction and a second portion of the TDD mode having a second transmission direction different from the first transmission direction; and send a TDD mode indicator within the first control region or the second control region, the TDD mode indicator being used to identify the determined TDD mode for the second TTI.

[0244] Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may further include a process, feature, unit, or instruction for identifying a symbol period of a reference signal for a TDD mode for a first TTI. Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may further include a process, feature, unit, or instruction for determining a position of one or more guard periods based at least in part on the identified symbol period of the reference signal.

[0245] In some examples of the methods, apparatus, and non-transitory computer-readable media described above, the reference signal includes a CRS or a DMRS.

[0246] Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may also include a process, feature, unit, or instruction for performing the following operations: identifying a third transmission direction associated with a third portion of a third TTI, the third TTI following the second TTI. In some examples of the methods, apparatuses, and non-transitory computer-readable media described above, the TDD mode for the second TTI includes a second guard period of the one or more guard periods, the second guard period being positioned at the end of the second TTI between the third portion and a second portion of the TDD mode having a second transmission direction, the second transmission direction being different from the third transmission direction.

[0247] Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may also include a process, feature, unit, or instruction for performing the following operations: identifying a third transmission direction associated with a third portion of a third TTI, the third TTI preceding the second TTI. In some examples of the methods, apparatuses, and non-transitory computer-readable media described above, the TDD mode for the second TTI includes a second guard period of the one or more guard periods, the second guard period being positioned at the beginning of the second TTI between the third portion and a first portion of the TDD mode having a first transmission direction, the first transmission direction being different from the third transmission direction.

[0248] Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may further include a process, feature, unit, or instruction for identifying a boundary of a symbol period of a TDD mode for a first TTI. Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may further include a process, feature, unit, or instruction for determining a position of a guard period in one or more guard periods based at least in part on the identified boundary.

[0249] In some examples of the methods, apparatus, and non-transitory computer-readable media described above, determining a position of the guard period includes aligning a boundary of the guard period with a boundary of the identified symbol period.

[0250] In some examples of the methods, apparatuses, and non-transitory computer-readable media described above, a first boundary of a guard period among the plurality of guard periods may be aligned with a symbol period of the TDD mode for the first TTI. In some examples of the methods, apparatuses, and non-transitory computer-readable media described above, a second boundary of the guard period may not be aligned with a symbol period of the TDD mode for the first TTI.

[0251] In some examples of the methods, apparatus, and non-transitory computer-readable media described above, the second duration includes an integer number of symbol periods or one time slot.

[0252] In some examples of the methods, apparatus, and non-transitory computer-readable media described above, the duration of the guard period may be less than the symbol period.

[0253] Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may further include a process, feature, unit, or instruction for identifying a transmission type associated with a first TTI. Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may further include a process, feature, unit, or instruction for identifying a location of one or more guard periods of a TDD mode within a second TTI based at least in part on the identified transmission direction associated with the first TTI.

[0254] In some examples of the methods, apparatus, and non-transitory computer-readable media described above, the identified transmission type associated with the first TTI may be an uplink transmission, or a downlink transmission, or a multicast broadcast single frequency network (MBSFN) transmission.

[0255] Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may further include a process, feature, unit, or instruction for identifying a time slot index associated with the first TTI. Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may further include a process, feature, unit, or instruction for identifying a location of one or more guard periods of a TDD mode based at least in part on the time slot index associated with the first TTI.

[0256] A method of wireless communication is described. The method may include receiving a first control message within a first control region having a first TTI having a first duration; receiving a second control message within a second control region having a second duration less than the first duration; receiving a TDD mode indicator for the second TTI in the first control region or the second control region; and determining one or more guard periods for a TDD mode for the second TTI based at least in part on the TDD mode indicator, a first guard period of the one or more guard periods being located between a first portion of the TDD mode having a first transmission direction and a second portion of the TDD mode having a second transmission direction different from the first transmission direction.

[0257] An apparatus for wireless communication is described. The apparatus may include: means for receiving a first control message within a first control region having a first TTI having a first duration; means for receiving a second control message within a second control region having a second duration less than the first duration; means for receiving a TDD mode indicator for the second TTI in the first control region or the second control region; and means for determining one or more guard periods of a TDD mode for the second TTI based at least in part on the TDD mode indicator, a first guard period of the one or more guard periods being located between a first portion of the TDD mode having a first transmission direction and a second portion of the TDD mode having a second transmission direction different from the first transmission direction.

[0258] Another apparatus for wireless communication is described. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. The instructions are operable to cause the processor to: receive a first control message within a first control region having a first TTI having a first duration; receive a second control message within a second control region having a second TTI having a second duration less than the first duration; receive a TDD mode indicator for the second TTI in the first control region or the second control region; and determine, based at least in part on the TDD mode indicator, one or more guard periods of a TDD mode for the second TTI, a first guard period of the one or more guard periods being located between a first portion of the TDD mode having a first transmission direction and a second portion of the TDD mode having a second transmission direction different from the first transmission direction.

[0259] A non-transitory computer-readable medium for wireless communication is described. The non-transitory computer-readable medium may include instructions operable to cause a processor to: receive a first control message within a first control region having a first duration, receive a second control message within a second control region having a second duration less than the first duration, receive a TDD mode indicator for the second TTI in the first control region or the second control region, and determine, based at least in part on the TDD mode indicator, one or more guard periods for a TDD mode for the second TTI, a first guard period of the one or more guard periods being located between a first portion of the TDD mode having a first transmission direction and a second portion of the TDD mode having a second transmission direction different from the first transmission direction.

[0260] Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may further include a process, feature, unit, or instruction for identifying a reference signal for a TDD mode for a first TTI. Some examples of the methods, apparatuses, and non-transitory computer-readable media described above may further include a process, feature, unit, or instruction for determining to skip monitoring a symbol period during a second TTI associated with the identified reference signal.

[0261] It should be noted that the methods described above describe possible implementations, and that operations and steps may be rearranged or otherwise modified, and that other implementations are possible. Furthermore, aspects from two or more of these methods may be combined.

[0262] One or more wireless communication systems described herein may support synchronous operation or asynchronous operation. For synchronous operation, base stations may have similar frame timing, and transmissions from different base stations may be approximately aligned in time. For asynchronous operation, base stations may have different frame timing, and transmissions from different base stations may not be aligned in time. The techniques described herein may be used for either synchronous or asynchronous operation.

[0263] Downlink transmissions described herein may also be referred to as forward link transmissions, and uplink transmissions may also be referred to as reverse link transmissions. Each communication link described herein (including, for example, Figure 1 and 2 The wireless communication systems 100 and 200 may include one or more carriers, where each carrier may be a signal composed of multiple subcarriers (eg, waveform signals of different frequencies).

[0264] The description set forth herein in conjunction with the accompanying drawings describes exemplary configurations and does not represent all examples that can be implemented or within the scope of the claims. The term "exemplary" as used herein means "serving as an example, instance, or illustration" and does not mean "preferred" or "having advantages over other examples." For the purpose of providing an understanding of the described techniques, the detailed description includes specific details. However, these techniques can be implemented without these specific details. In some instances, well-known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0265] In the accompanying drawings, similar components or features may have the same reference label. In addition, various components of the same type may be distinguished by following the reference label with a dash and a second label to distinguish between similar components. If only the first reference label is used in the specification, the description may apply to any of the similar components having the same first reference label, regardless of the second reference label.

[0266] The information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0267] The various illustrative blocks and modules described in conjunction with the disclosure herein may be implemented or executed using a general purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in an alternative embodiment, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, a combination of one or more microprocessors and a DSP core, or any other such configuration).

[0268] The functions described herein can be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions can be stored as one or more instructions or codes on a computer-readable medium or transmitted therethrough. Other examples and implementations are within the scope of this disclosure and the appended claims. For example, due to the nature of software, the functions described above can be implemented using software executed by a processor, hardware, firmware, hardwiring, or a combination of any of these. The features used to implement the functions can also be physically located in various locations, including being distributed so that parts of the functions are implemented in different physical locations. In addition, as used herein, including in the claims, as used in a list of items (e.g., a list of items ending with a phrase such as "at least one of..." or "one or more of..."), "or" indicates an inclusive list, so that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). In addition, as used herein, the phrase "based on" should not be interpreted as a reference to a closed set of conditions. For example, an exemplary step described as "based on condition A" can be based on both condition A and condition B without departing from the scope of this disclosure. In other words, as used herein, the phrase "based on" should be interpreted in the same manner as the phrase "based at least in part on" is interpreted.

[0269] Computer readable medium includes both non-transitory computer storage medium and communication medium, and described communication medium includes any medium that promotes computer program to be transferred from one place to another place.Non-transitory storage medium can be any available medium that can be accessed by general or special-purpose computer.By way of example and not limitation, non-transitory computer readable medium can include RAM, ROM, electrically erasable programmable read-only memory (EEPROM), compact disc (CD) ROM or other optical disc storage, magnetic disk storage or other magnetic storage device or can be used for carrying or storing desired program code unit and any other non-transitory medium that can be accessed by general or special-purpose computer or general or special-purpose processor in the form of instruction or data structure.In addition, any connection is suitably referred to as computer readable medium.For example, if software is sent from website, server or other remote source using coaxial cable, optical fiber cable, twisted pair, digital subscriber line (DSL) or wireless technology (such as infrared, radio and microwave), then coaxial cable, optical fiber cable, twisted pair, digital subscriber line (DSL) or wireless technology (such as infrared, radio and microwave) are included in the definition of medium. As used herein, disk and disc include CDs, laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

[0270] The description herein is provided to enable those skilled in the art to implement or use the present disclosure. Various modifications to the present disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the scope of the present disclosure. Therefore, the present disclosure is not limited to the examples and designs described herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0271] The equivalents of all structures and functions of the elements of the various aspects described throughout this disclosure, known to those of ordinary skill in the art or to be known later, are expressly incorporated herein by reference, and are intended to be included by the claims. In addition, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is clearly recorded in the claims. Words "module," "mechanism," "element," "device," "component," etc. may not be substitutes for the word "unit." Thus, no claim element is to be interpreted as a unit plus function unless the element is explicitly recorded using the phrase "unit for ..."

Claims

1. A method for wireless communication at a user equipment (UE), comprising: receiving control signaling from a network device identifying a time division duplex mode, the time division duplex mode indicating one or more transmission directions for a short transmission time interval, the short transmission time interval being shorter than a time slot, and the time division duplex mode indicating at least one flexible symbol, wherein the transmission direction of the at least one flexible symbol is reconfigurable for uplink transmission or downlink transmission; receiving a downlink control information message from the network device, the downlink control information message including an indication to reconfigure a transmission direction for at least a portion of the short transmission time interval to uplink or downlink; and Communicating with the network device in the short transmission time interval is performed based at least in part on the reconfiguration.

2. The method according to claim 1, further comprising: The downlink control information message is received within the time slot.

3. The method according to claim 2, wherein: The time division duplex mode indicates the one or more transmission directions for the time slots including the short transmission time interval, wherein receiving the downlink control information message comprises: The downlink control information message is received in the time slot according to the time division duplex mode.

4. The method according to claim 1, wherein The reconfiguration changes the transmission direction for the at least one flexible symbol to uplink or downlink.

5. The method according to claim 1, further comprising: A modified time division duplex pattern is identified based at least in part on the reconfiguration, wherein the modified time division duplex pattern applies to a predetermined number of short transmission time intervals that includes the short transmission time interval.

6. The method according to claim 1, further comprising: A time division duplex mode indicator is received via the downlink control information message, wherein the time division duplex mode indicator includes the indication of the reconfiguration.

7. The method according to claim 1, wherein The control signaling includes radio resource control signaling.

8. The method according to claim 1, further comprising: It is identified that the time division duplex mode applies to a predetermined number of transmission time intervals including the short transmission time interval.

9. A method for wireless communication at a network device, comprising: sending control signaling identifying a time division duplex mode to a user equipment (UE), the time division duplex mode indicating one or more transmission directions for a short transmission time interval, the short transmission time interval being shorter than a time slot, and the time division duplex mode indicating at least one flexible symbol, wherein the transmission direction of the at least one flexible symbol is reconfigurable for uplink transmission or downlink transmission; sending a downlink control information message to the UE, the downlink control information message including an indication of reconfiguring a transmission direction for at least a portion of the short transmission time interval to uplink or downlink; and Communicating with the UE in the short transmission time interval is performed based at least in part on the reconfiguration.

10. The method according to claim 9, further comprising: The downlink control information message is sent within the time slot.

11. The method according to claim 10, wherein: The time division duplex mode indicates the one or more transmission directions for the time slots including the short transmission time interval, wherein sending the downlink control information message comprises: The downlink control information message is sent in the time slot according to the time division duplex mode.

12. The method according to claim 9, wherein The reconfiguration changes the transmission direction for the at least one flexible symbol to uplink or downlink.

13. The method according to claim 9, further comprising: A modified time division duplex pattern is identified based at least in part on the reconfiguration, wherein the modified time division duplex pattern applies to a predetermined number of short transmission time intervals that includes the short transmission time interval.

14. The method according to claim 9, further comprising: A time division duplex mode indicator is sent via the downlink control information message, wherein the time division duplex mode indicator includes the indication of the reconfiguration.

15. The method according to claim 9, wherein The control signaling includes radio resource control signaling.

16. The method according to claim 9, further comprising: It is identified that the time division duplex mode applies to a predetermined number of transmission time intervals including the short transmission time interval.

17. An apparatus for wireless communication at a user equipment (UE), comprising: processor; a memory in electronic communication with the processor; as well as Instructions stored in the memory and operable, when executed by the processor, to cause the apparatus to: receiving control signaling from a network device identifying a time division duplex mode, the time division duplex mode indicating one or more transmission directions for a short transmission time interval, the short transmission time interval being shorter than a time slot, and the time division duplex mode indicating at least one flexible symbol, wherein the transmission direction of the at least one flexible symbol is reconfigurable for uplink transmission or downlink transmission; receiving a downlink control information message from the network device, the downlink control information message including an indication to reconfigure a transmission direction for at least a portion of the short transmission time interval to uplink or downlink; and Communicating with the network device in the short transmission time interval is performed based at least in part on the reconfiguration.

18. The device according to claim 17, wherein The short transmission time interval is included in the time slot, wherein the instructions are further executable by the processor to cause the apparatus to perform the following operations: The downlink control information message is received within the time slot.

19. The device according to claim 18, wherein The time division duplex mode indicates the one or more transmission directions for the time slots including the short transmission time interval, wherein the instructions for receiving the downlink control information message are further executable by the processor to cause the apparatus to perform the following operations: The downlink control information message is received in the time slot according to the time division duplex mode.

20. The apparatus according to claim 17, wherein The reconfiguration changes the transmission direction for the at least one flexible symbol to uplink or downlink.

21. The apparatus according to claim 17, wherein The instructions may also be executed by the processor to cause the device to perform the following operations: A modified time division duplex pattern is identified based at least in part on the reconfiguration, wherein the modified time division duplex pattern applies to a predetermined number of short transmission time intervals that includes the short transmission time interval.

22. The apparatus according to claim 17, wherein The instructions may also be executed by the processor to cause the device to perform the following operations: A time division duplex mode indicator is received via the downlink control information message, wherein the time division duplex mode indicator includes the indication of the reconfiguration.

23. The apparatus according to claim 17, wherein The control signaling includes radio resource control signaling.

24. The apparatus according to claim 17, wherein The instructions may also be executed by the processor to cause the device to perform the following operations: It is identified that the time division duplex mode applies to a predetermined number of transmission time intervals including the short transmission time interval.

25. An apparatus for wireless communication at a network device, comprising: processor; a memory in electronic communication with the processor; as well as Instructions stored in the memory and operable, when executed by the processor, to cause the apparatus to: sending control signaling identifying a time division duplex mode to a user equipment (UE), the time division duplex mode indicating one or more transmission directions for a short transmission time interval, the short transmission time interval being shorter than a time slot, and the time division duplex mode indicating at least one flexible symbol, wherein the transmission direction of the at least one flexible symbol is reconfigurable for uplink transmission or downlink transmission; sending a downlink control information message to the UE, the downlink control information message including an indication of reconfiguring a transmission direction for at least a portion of the short transmission time interval to uplink or downlink; and Communicating with the UE in the short transmission time interval is performed based at least in part on the reconfiguration.

26. The device according to claim 25, wherein The instructions may also be executed by the processor to cause the device to perform the following operations: The downlink control information message is sent within the time slot.

27. The device according to claim 26, wherein The time division duplex mode indicates the one or more transmission directions for the time slots including the short transmission time interval, wherein the instructions for sending the downlink control information message are further executable by the processor to cause the apparatus to perform the following operations: The downlink control information message is sent according to the time division duplex mode.

28. The apparatus according to claim 25, wherein The reconfiguration changes the transmission direction for the at least one flexible symbol to uplink or downlink.

29. The apparatus according to claim 25, wherein The instructions may also be executed by the processor to cause the device to perform the following operations: A modified time division duplex pattern is identified based at least in part on the reconfiguration, wherein the modified time division duplex pattern applies to a predetermined number of short transmission time intervals that includes the short transmission time interval.

30. The apparatus of claim 25, wherein: The instructions may also be executed by the processor to cause the device to perform the following operations: A time division duplex mode indicator is sent via the downlink control information message, wherein the time division duplex mode indicator includes the indication of the reconfiguration.

31. The apparatus according to claim 25, wherein The control signaling includes radio resource control signaling.

32. The apparatus according to claim 25, wherein The instructions may also be executed by the processor to cause the device to perform the following operations: It is identified that the time division duplex mode applies to a predetermined number of transmission time intervals including the short transmission time interval.

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