Patent Description:
The following relates generally to wireless communication, and more specifically to self-contained uplink for reduced duration transmission time intervals (TTIs).

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. A wireless multiple-access communications system may include a number of base stations, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE).

Wireless multiple-access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example telecommunication standard is Long Term Evolution (LTE). LTE is designed to improve spectral efficiency, lower costs, improve services, make use of new spectrum, and better integrate with other open standards. LTE may 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.

A base station and a UE in a system employing multiple-access technology may operate according to a low latency physical (PHY) layer timing structure. Low latency operations (for example, operations based on a reduced transmission time interval (TTI)) may provide for reduced delay between a transmission and a HARQ response, for example. Low latency operation may, however, introduce issues related to receiving various transmissions relative other transmissions, and low latency scheduling may affect device operation, such as demodulation, in either the uplink or downlink.

QUALCOMM INCORPORATED "TTI shortening and reduced processing time for UL transmission" 3GPP Draft; R1-<NUM> provides design details that deal with the uplink transmission portion of TTI shortening and reduced processing time.

<CIT> relates to communicating in a wireless network. An uplink resource grant can be received from a network entity for communicating in the wireless network. A transmission time interval (TTI) for an uplink transmission within a subframe based on the uplink resource grant can be determined, wherein the TTI comprises one or more symbols which are a subset of a plurality of symbols in the subframe.

<NPL> discusses specification impacts caused by TTI shortening and reduced processing times.

The invention is defined in independent claims. Dependent claims concern particular embodiments of the invention. Any subject matter presented in the description but not falling under the claims constitutes an aspect of the disclosure which may be useful for understanding the invention.

According to aspects of the disclosure, a user equipment (UE) may receive an uplink resource allocation associated with low latency, two-symbol transmission time intervals (TTIs). The uplink resource allocation may schedule the UE for transmission of demodulation reference signals (DM-RS) or data, or both, during two-symbol TTIs. Including the DM-RS in the two-symbol TTI with data may facilitate demodulation by a base station. The UE may, based on the uplink resource allocation, determine whether a DM-RS is to be transmitted in a symbol of the two-symbol TTI. In some cases, the UE may transmit the DM-RS in a first symbol of the two-symbol TTI and transmit data in a second symbol of the two-symbol TTI. In such a scenario, the UE may transmit a subsequent two-symbol TTI that includes two symbols of data. In some cases, the first symbol conveying the DM-RS of the UE may also convey DM-RS of another UE. The second symbol of the two-symbol TTI may include data from one of the UEs and the two symbols of a subsequent two-symbol TTI may include data from the other UE.

A method of wireless communication is described. The method may include receiving an uplink resource allocation that is associated with a two-symbol TTI and determining whether a DM-RS is scheduled to be transmitted in one symbol of the two-symbol TTI as part of the uplink resource allocation. The method may include transmitting data or the DM-RS, or both, during the two-symbol TTI based at least in part on the determination of whether the DM-RS is scheduled.

An apparatus for wireless communication is described. The apparatus may include means for receiving an uplink resource allocation that is associated with a two-symbol TTI and means for determining whether a DM-RS is scheduled to be transmitted in one symbol of the two-symbol TTI as part of the uplink resource allocation. The apparatus may include means for transmitting data or the DM-RS, or both, during the two-symbol TTI based at least in part on the determination of whether the DM-RS is scheduled.

A further apparatus is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be operable to cause the processor to receive an uplink resource allocation that is associated with a two-symbol TTI and determine whether a DM-RS is scheduled to be transmitted in one symbol of the two-symbol TTI as part of the uplink resource allocation. The instructions may be operable to cause the processor to transmit data or the DM-RS, or both, during the two-symbol TTI based at least in part on the determination of whether the DM-RS is scheduled.

A non-transitory computer readable medium for wireless communication is described. The non-transitory computer-readable medium may include instructions to cause a processor to receive an uplink resource allocation that is associated with a two-symbol TTI and determine whether a DM-RS is scheduled to be transmitted in one symbol of the two-symbol TTI as part of the uplink resource allocation. The non-transitory computer-readable medium may include instructions to cause the processor to transmit data or the DM-RS, or both, during the two-symbol TTI based on the determination of whether the DM-RS is scheduled.

Some examples of the method, apparatus, or non-transitory computer-readable medium described above may further include processes, features, means, or instructions for determining that the DM-RS is scheduled, wherein the DM-RS and the data are transmitted during the two-symbol TTI, and transmitting additional data during a subsequent TTI, wherein the subsequent TTI excludes another DM-RS. In some cases, the number of symbol periods between the symbol with the DM-RS and the subsequent TTI is an odd number. In some cases, transmitting the data or the DM-RS, or both, includes transmitting the DM-RS during a first symbol of the two-symbol TTI and transmitting the data during a second symbol of the two-symbol TTI. In some cases, transmitting the data or the DM-RS, or both, includes transmitting the DM-RS during a first symbol of the two-symbol TTI and refraining from transmitting during a second symbol of the two-symbol TTI, wherein resources of the second symbol TTI are available for communications by another device.

In some examples, the first symbol of the two-symbol TTI comprises DM-RS transmissions from two or more UEs. Some examples of the method, apparatus, or non-transitory computer-readable medium described above may further include processes, features, means, or instructions for transmitting data during a subsequent TTI that excludes another DM-RS. In some cases, the uplink resource allocation is received in a downlink control channel during a prior two-symbol TTI. In some examples, the uplink resource allocation is received in a downlink control channel of during TTI that has a longer duration than the two-symbol TTI.

A method of wireless communication is described. The method may include transmitting an uplink resource allocation that is associated with a two-symbol TTI and determining whether a DM-RS is scheduled to be transmitted in one symbol of the two-symbol TTI as part of the uplink resource allocation. The method may include receiving data or the DM-RS, or both, during the two-symbol TTI based at least in part on the determination of whether the DM-RS is scheduled.

An apparatus for wireless communication is described. The apparatus may include means for transmitting an uplink resource allocation that is associated with a two-symbol TTI and means for determining whether a DM-RS is scheduled to be transmitted in one symbol of the two-symbol TTI as part of the uplink resource allocation. The apparatus may include means for receiving data or the DM-RS, or both, during the two-symbol TTI based at least in part on the determination of whether the DM-RS is scheduled.

A further apparatus is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be operable to cause the processor to transmit an uplink resource allocation that is associated with a two-symbol TTI and determine whether a DM-RS is scheduled to be transmitted in one symbol of the two-symbol TTI as part of the uplink resource allocation. The instructions may be operable to cause the processor to receive data or the DM-RS, or both, during the two-symbol TTI based at least in part on the determination of whether the DM-RS is scheduled.

A non-transitory computer readable medium for wireless communication is described. The non-transitory computer-readable medium may include instructions to cause a processor to transmit an uplink resource allocation that is associated with a two-symbol TTI and determine whether a DM-RS is scheduled to be transmitted in one symbol of the two-symbol TTI as part of the uplink resource allocation. The non-transitory computer-readable medium may include instructions to cause the processor to receive data or the DM-RS, or both, during the two-symbol TTI based on the determination of whether the DM-RS is scheduled.

Some examples of the method, apparatus, or non-transitory computer-readable medium described above may further include processes, features, means, or instructions for determining that the DM-RS is scheduled, wherein the DM-RS and the data are received during the two-symbol TTI and receiving additional data during a subsequent TTI, wherein the subsequent TTI excludes another DM-RS. In some cases, receiving the data or the DM-RS, or both, includes receiving the DM-RS during a first symbol of the two-symbol TTI and receiving the data during a second symbol of the two-symbol TTI. In some examples, receiving the data or the DM-RS, or both, includes receiving the DM-RS during a first symbol of the two-symbol TTI, wherein the DM-RS is associated with a first UE and receiving another DM-RS during the first symbol of the two-symbol TTI, wherein the other DM-RS is associated with a second UE. In some examples, the method, apparatus, or non-transitory computer-readable medium described above may further include processes, features, means, or instructions for receiving data from the second UE during a second symbol of the two-symbol TTI and receiving data from the first UE during a subsequent TTI that excludes another DM-RS.

In some cases, a wireless system may utilize low latency operations. This may be achieved by using a reduced transmission time interval (TTI) as compared with other TTIs in the system or communication schemes. A Long Term Evolution (LTE) system, for instance, utilizes a TTI of <NUM> duration, which is referred to as a subframe and which, as discussed below, may include time divisions referred to as symbols or symbol periods. But low latency operations may be employed via TTIs that have a substantially shorter duration than an LTE subframe. A low latency TTI may be just one or two symbols in duration, for example. These low latency TTIs may be scheduled to coexist or complement longer duration TTIs.

In some cases, a low latency uplink TTI (e.g., a two-symbol TTI) may include one or more symbols of that include data transmission. For instance, the data may be transmitted in physical uplink control channel (PUSCH), which, as discussed below may be referred to as a low latency, short, or self-contained PUSCH (sPUSCH). According to the techniques described herein, the low latency TTI conveying sPUSCH may be preceded by another low latency TTI (e.g., a two-symbol TTI) or symbol of a low latency TTI (e.g., one symbol of a two-symbol TTI) conveying a demodulation reference signal (DM-RS), which may be used in the demodulation of the sPUSCH. So in some cases, the low latency TTI conveying sPUSCH may also include the DM-RS. Thus, the low latency TTI may be self-contained in that it may include both data and signaling used to facilitate demodulation of the data. In some cases, a single DM-RS symbol in a low latency TTI may be transmitted for multiple sPUSCH symbols from the same user equipment (UE). In some examples, a single DM-RS symbol in a low latency TTI may convey DM-RS for multiple UEs and may precede sPUSCH symbols (in the same or different low latency TTIs) corresponding to each of the UEs.

Aspects of this disclosure introduced above are described below in the context of a wireless communication system. Specific examples are then described for various low latency transmission techniques for DM-RS are described. Additionally, specific examples for self-contained DM-RS transmissions are described. These and other aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts.

<FIG> illustrates an example of a wireless communications system <NUM> that supports self-contained uplink for reduced duration transmission time intervals in accordance with various aspects of the present disclosure. The wireless communications system <NUM> includes base stations <NUM>, UEs <NUM>, and a core network <NUM>. In some examples, the wireless communications system <NUM> may be an LTE or LTE-Advanced (LTE-A) network.

The base stations <NUM> may wirelessly communicate with the UEs <NUM> via one or more base station antennas. The communication links <NUM> shown in wireless communications system <NUM> may include uplink (UL) transmissions from a UE <NUM> to a base station <NUM>, or downlink (DL) transmissions, from a base station <NUM> to a UE <NUM>. In some cases, wireless communications system <NUM> may support operation on multiple cells or carriers, a feature which may be referred to as carrier aggregation (CA) or multi-carrier operation. A carrier may also be referred to as a component carrier (CC), a layer, a channel, etc. The terms "carrier," "component carrier," "cell," and "channel" may be used interchangeably herein. A UE <NUM> may thus be configured with multiple downlink CCs and one or more uplink CCs for carrier aggregation. Carrier aggregation may be used with both frequency division duplexed (FDD) and time division duplexed (TDD) component carriers.

The base stations <NUM> may interface with the core network <NUM> through backhaul links <NUM> (e.g., S1, etc.). The base stations <NUM> may also communicate with one another over backhaul links <NUM> (e.g., X1, etc.) either directly or indirectly (e.g., through core network <NUM>). In some cases, base stations <NUM> may perform radio configuration and scheduling for communication with the UEs <NUM>, or may operate under the control of a base station controller (not shown). In various examples, base stations <NUM> may be macro cells, small cells, hot spots, or the like. The base stations <NUM> may also be referred to as eNodeBs (eNBs) <NUM> in some examples. The base stations <NUM> may support and may utilize low latency operations (e.g., two-symbol TTIs) to facilitate faster processing of certain delay intolerant communications with low latency capable UEs <NUM>.

Time intervals in LTE may be expressed in multiples of a basic time unit (e.g., the sampling period, Ts= <NUM>/<NUM>,<NUM>,<NUM> seconds). Time resources may be organized according to radio frames of length of <NUM> (Tf = <NUM>·Ts), which may be identified by a system frame number (SFN) ranging from <NUM> to <NUM>. Each frame may include ten <NUM> subframes numbered from <NUM> to <NUM>. A subframe may be further divided into two. <NUM> slots, each of which contains <NUM> or <NUM> modulation symbol periods (depending on the length of the cyclic prefix prepended to each symbol). Excluding the cyclic prefix, each symbol contains <NUM> sample periods. In some cases the subframe may be the smallest scheduling unit, also known as a TTI. In other cases, a TTI may be shorter than a subframe (e.g., the TTI may be two symbols) or may be dynamically selected (e.g., in short TTI bursts or in selected component carriers using short TTIs).

The communication networks that may accommodate some of the various disclosed examples, including wireless communications system <NUM> of <FIG>, may be packet-based networks that operate according to a layered protocol stack and data in the user plane may be based on Internet protocol (IP). A radio link control (RLC) layer may perform packet segmentation and reassembly to communicate over logical channels. A medium access control (MAC) layer may perform priority handling and multiplexing of logical channels into transport channels. In the control plane, the radio resource control (RRC) protocol layer may provide establishment, configuration, and maintenance of an RRC connection between a UE <NUM> and the base stations <NUM>. In some cases, RRC signaling may be utilized to signal DM-RS patterns, including low latency DM-RS patterns, and carrier configurations to UEs <NUM>. The RRC protocol layer may also be used for core network <NUM> support of radio bearers for the user plane data.

Data may be divided into logical channels, transport channels, and physical layer channels. Channels may also be classified into Control Channels and Traffic Channels. DL physical channels may, for example, include physical broadcast channel (PBCH) for broadcast information, physical control format indicator channel (PCFICH) for control format information, physical downlink control channel (PDCCH) for control and scheduling information, physical HARQ indicator channel (PHICH) for HARQ status messages, physical downlink shared channel (PDSCH) for user data and physical multicast channel (PMCH) for multicast data. UL physical channels may include physical random access channel (PRACH) for access messages, physical uplink control channel (PUCCH) for control data, and physical uplink shared channel (PUSCH) for user data. In some cases, additional low latency physical channels may be employed to support low latency operations. These may include a low latency PDCCH (sPDCCH) and low latency PDSCH (sPDSCH) in the downlink and low latency PUCCH (sPUCCH) and low latency PUSCH (sPUSCH) in the uplink.

PDCCH may carry downlink control information (DCI) in control channel elements (CCEs), which may consist of nine logically contiguous resource element groups (REGs), where each REG contains <NUM> resource elements (REs). Likewise, uPDCCH may carry DCI in low latency CCEs (uCCEs), which may consist of low latency REGs (uREGs). DCI includes information regarding DL scheduling assignments, UL resource grants, transmission scheme, UL power control, HARQ information, modulation and coding scheme (MCS) and other information. The size and format of the DCI messages can differ depending on the type and amount of information that is carried by the DCI. For example, if spatial multiplexing is supported, the size of the DCI message is large compared to contiguous frequency allocations. Similarly, for a system such as wireless communications system <NUM> that employs Multiple Input Multiple Output (MIMO), the DCI may also include additional signaling information. DCI size and format may depend on the amount of information as well as factors such as bandwidth, the number of antenna ports, and duplexing mode being utilized. The size and format of the DCI may determine the number of resources a wireless communications system <NUM> allocates to the PDCCH or sPDCCH.

The wireless communications system <NUM> may transmit control information on the PDCCH corresponding to a legacy downlink or uplink transmission. The control information may be used by a UE <NUM> to determine a resource allocation in a following subframe. For instance, a legacy UE <NUM> may determine a reference signal pattern, what resources are allocated to the PDSCH, and the like for the subframe. The system may additionally transmit a sPDCCH that communicates similar control information corresponding to a low latency transmission, which a low latency UE <NUM> may use to determine a low-latency resource allocation. A low latency UE <NUM> may, for instance, determine that a low latency TTI (e.g., a two-symbol TTI) is scheduled and determine resources that are allocated to sPUSCH and DM-RS during the low latency TTI. For example, a UE <NUM> may receive an uplink grant (e.g., conveyed by sPDCCH) that indicates to the UE <NUM> that a two-symbol TTI is to be transmitted that includes both data (e.g., conveyed by sPUSCH) and DM-RS. Thus, a UE <NUM> may receive an uplink resource allocation via a downlink control channel (e.g., sPDCCH) that is associated with two-symbol TTIs.

<FIG> illustrates an example of a wireless communications system <NUM> that supports self-contained uplink for reduced duration transmission time intervals in accordance with various aspects of the present disclosure. Wireless communications system <NUM> may include UE <NUM>-a, UE <NUM>-b, and base station <NUM>-a, which may be examples of a UE <NUM> or a base station <NUM> described above with reference to <FIG>. Base station <NUM>-a may communicate with UE <NUM>-b via communication link <NUM>, which may utilize legacy TTIs <NUM>, and with UE <NUM>-a via communications link <NUM>, which may utilize low latency TTIs <NUM> and <NUM>, when the UEs <NUM> are within geographic coverage area <NUM>-a, as generally described above with reference to <FIG>. Low latency TTIs <NUM> may be two-symbol TTIs as described herein.

The UEs <NUM> may transmit DM-RS to base station <NUM>-a. The DM-RS from a UE <NUM> may be used by base station <NUM>-a to equalize and demodulate transmissions from that particular UE <NUM>. For example, DM-RS from UE <NUM>-a may be used by base station <NUM>-a to demodulate data transmissions (e.g., conveyed by sPUSCH) from UE <NUM>-a. In some cases, a UE <NUM> may send DM-RS in a two-symbol TTI (e.g., two-symbol TTI <NUM>) that also includes data (e.g., sPUSCH). In some cases, the DM-RS may be used for subsequent data transmissions from that UE <NUM>. Also on the uplink, a UE <NUM> may transmit a periodic sounding reference signal (SRS) for link adaptation.

A frame structure may be used within the wireless communications system <NUM> to organize physical resources. A frame may be a <NUM> interval that may be further divided into <NUM> equally sized subframes, as depicted in <FIG>. Each subframe may include two consecutive time slots. Each slot may include <NUM> or <NUM> OFDMA symbol periods. A resource element consists of one symbol period and one subcarrier (a <NUM> frequency range). A resource block may contain <NUM> consecutive subcarriers in the frequency domain and, for a normal cyclic prefix in each OFDM symbol, <NUM> consecutive OFDM symbols in the time domain (<NUM> slot), or <NUM> 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). Thus, the more resource blocks that a UE receives and the higher the modulation scheme, the higher the data rate may be for the UE.

In some cases, and as discussed above, an LTE subframe, such as TTI <NUM>, may be the smallest scheduling unit, also known as a TTI. In other cases, a TTI may be shorter than a subframe or may be dynamically selected (e.g., in short TTI bursts or in selected component carriers using short TTIs). Wireless communications system <NUM> may employ TTIs of varying lengths to communicate with low latency and legacy UEs <NUM>. For low latency or low latency operation, TTIs with short durations, such as two-symbol TTI <NUM>, may be employed. In some cases, using shorter length TTIs may reduce over-the-air latency. For example, one-symbol TTI <NUM> or two-symbol TTIs <NUM>, which may have a duration of one and two LTE symbol periods, respectively, may help reduce HARQ latency as compared with legacy TTIs <NUM> (e.g., an LTE subframe). Such latency gains may be realized while maintaining compatibility with legacy operation because wireless communications system <NUM> may utilize LTE numerology for low latency operation such that the two-symbol TTI duration may be different while tone spacing and symbol duration may be the same. That is, a two-symbol TTI configuration may use the same tone spacing (e.g., <NUM>) and symbol duration (e.g., approximately <NUM> for a normal CP) as a legacy TTI configuration.

<FIG> illustrates an example of a frame configuration <NUM> for self-contained uplink for reduced duration transmission time intervals in accordance with various aspects of the present disclosure. Frame configuration <NUM> may illustrate aspects of a transmission between a UE <NUM>, such as low latency or legacy UE <NUM>, and a base station <NUM>, as described above with reference to <FIG> and <FIG>. Frame configuration <NUM> may include a frame <NUM>, which may include a number of low latency subframes <NUM> scheduled for downlink or uplink. Low latency subframes <NUM> may be examples of legacy TTIs <NUM> as described with reference to <FIG>. In some case, transmissions using frame <NUM> may be configured to support low latency operation using short duration TTIs. Frame <NUM> may be used in a FDD or TDD system.

Frame <NUM> may include a number of subframes configured as low latency downlink subframes <NUM> and low latency uplink subframes <NUM>. In some cases, frame <NUM> may include both low latency subframes and non-low latency subframes. The distribution of low latency downlink subframes <NUM> and low latency uplink subframes <NUM> may be determined by a base station <NUM> according to predefined uplink/downlink TDD configurations, for example. Between the low latency downlink subframes <NUM> and the low latency uplink subframes <NUM>, the base station may not schedule any information. Such scheduling gaps may allow a UE <NUM> to transition from a downlink setup to an uplink setup. Thus, frame <NUM> may include special subframes <NUM> which act as guard periods for occasions when communication direction changes (e.g., from downlink to uplink).

Low latency subframes <NUM> may be partitioned into smaller segments-that is, larger TTIs, such as subframes, may include smaller TTIs, such as two-symbol TTIs <NUM>. For example, low latency subframes <NUM> may include a number of low latency symbols <NUM>. Two low latency symbols <NUM> may be combined to form a two-symbol TTI <NUM>. A two-symbol TTI may be scheduled to convey downlink data (e.g., downlink symbols) or uplink data (e.g., uplink symbols such as sPUSCH and DM-RS symbols). In some low-latency configurations, a base station <NUM> may schedule the low latency symbols <NUM> of a low latency subframe <NUM> according to the same or different direction as a low latency subframe <NUM>. A HARQ process may be performed at the symbol-level (e.g., within a low latency subframe <NUM>). Two-symbol TTIs may allow a system to, in the UL, more readily implement frequency hopping while maintaining a single carrier waveform (e.g., an approximation of an SC-FDM waveform).

In some cases, a base station <NUM> may schedule gaps between communication direction changes at the symbol-level (e.g., the gaps may be within a low latency subframe <NUM>). For example, a base station <NUM> may schedule guard periods <NUM> and <NUM>-a, which may allow a low latency UE <NUM> to change configurations.

A base station <NUM> may use control signaling to support different TTI configurations or to support low latency operation. For instance, a base station <NUM> may signal to a low latency UE <NUM> which two-symbol TTIs <NUM> are for uplink. In response, the UE <NUM> may include DM-RS symbols in the same or a prior TTI. The UE <NUM> may also include data (e.g., sPUSCH) in the same or a prior TTI. The base station <NUM> may schedule TTIs based on two symbol intervals, such as DL or UL two-symbol TTIs <NUM>. In some cases, a base station <NUM> may signal a DM-RS trigger that alerts a UE <NUM> that DM-RS is to be sent with, or prior to, data (e.g., sPUSCH). Absence of the DM-RS trigger may indicate to a UE <NUM> that DM-RS is not to be sent with the data. In some cases, a base station <NUM> may also signal a DM-RS offset. Both the DM-RS trigger and the DM-RS offset may be included in an uplink grant. The DM-RS trigger may be a bit and the DM-RS offset may be a field.

The location of the uplink grant may point to an uplink two-symbol TTI location. For example, if the uplink grant is in two-symbol TTI N and if the uplink grant points to N + <NUM>, the uplink two-symbol TTI may be transmitted in two-symbol TTI N + <NUM>. In such a scenario, the DM-RS trigger may indicate if there is a DM-RS transmission in the first symbol in two-symbol TTI N + <NUM>. The DM-RS offset may be an additional delay in two-symbol TTI transmissions. For example, if the DM-RS offset is zero, the data may be transmitted in two-symbol TTI N + <NUM>. If the DM-RS offset is x, then the data may be transmitted in TTI N + <NUM> + x. Thus, if DM-RS is triggered and the DM-RS offset is zero, the DM-RS and data will be transmitted in the same two-symbol TTI. In that case, the DM-RS will be transmitted in the first symbol and the data (e.g., sPUSCH) will be transmitted in the remaining symbol. If the DM-RS is not triggered, or the DM-RS offset is non-zero, then the data (e.g., sPUSCH) may be transmitted in a later two-symbol TTI than the DM-RS (e.g., the data will be transmitted in both symbols of a two-symbol TTI). In the case where data (e.g., uPUSCH) is transmitted in two-symbol TTI N + <NUM> + x, a retransmission uplink grant may be transmitted in two-symbol TTI N + <NUM> + x + <NUM> (assuming it takes <NUM> two-symbol TTIs to process the uPUSCH).

<FIG> illustrate examples of uplink transmissions <NUM>-a, <NUM>-b, and <NUM>-c that support self-contained uplink for reduced duration transmission time intervals in accordance with various aspects of the present disclosure. Uplink transmissions <NUM>-a, <NUM>-b, and <NUM>-c may illustrate aspects of an uplink transmission between a UE <NUM>, such as a low latency UE <NUM>, and a base station <NUM>, as described above with reference to <FIG>. Uplink transmissions <NUM> may be part of a frame <NUM> such as described in <FIG> and may include two-symbol TTIs <NUM>. In a wireless communications system that uses two-symbol TTIs, there may be one DM-RS symbol (e.g., a DM-RS symbol <NUM>) and two sPUSCH symbols (e.g., sPUSCH symbols <NUM>) per uplink transmission (e.g., uplink transmissions <NUM>). The DM-RS symbol may be transmitted before the sPUSCH symbols to relax (e.g., lengthen) the decoding time. In some cases, DM-RS may be reused for a UE <NUM> that transmits sPUSCH continuously or frequently. In some examples, overlapping DM-RS with different cyclic shifts may be used to separate DM-RS from different UEs <NUM> when multiple UEs <NUM> transmit sPUSCH. That is, cyclic prefix shifting may be used to distinguish DM-RS that are sent by multiple UEs <NUM> in the same symbol of a two-symbol TTI.

Uplink transmission <NUM>-a may include a DM-RS symbol <NUM>-a that is transmitted before sPUSCH symbol <NUM>-a and sPUSCH symbol <NUM>-b. The DM-RS symbol <NUM>-a and sPUSCH symbols <NUM>-a and <NUM>-b may be transmitted by the same UE <NUM>. The DM-RS symbol <NUM>-a may be separated from another DM-RS symbol (e.g., from another UE <NUM>) via cyclic shifting. In some cases, a configurable delay <NUM> may be introduced between the DM-RS symbol <NUM>-a and the sPUSCH symbols <NUM>. The configurable delay may be a number of symbol periods, or two-symbol TTIs periods, between a symbol with the DM-RS and the subsequent TTI. The number of symbol periods may include an even or odd integer number. The configurable delay <NUM> may temporally position the DM-RS symbol <NUM>-a in an even or odd symbol in a <NUM>-symbol TTI. Thus, two DM-RS symbols may be separated via cyclic shifting and/or via time division multiplexing (TDM) (e.g., temporally).

In some cases, as is shown in <FIG>, a DM-RS trigger (e.g., sent in a downlink control message such as an uplink grant) may be used to suppress the DM-RS transmission when a UE <NUM> has repeated sPUSCH transmissions. For example, a UE <NUM> (e.g., UE0) may be scheduled to transmit sPUSCH in two consecutive two-symbol TTIs <NUM>. In such a scenario, a DM-RS symbol <NUM>-b may be transmitted before the first two-symbol TTI transmission (e.g., two-symbol TTI <NUM>-b, which may include sPUSCH symbol <NUM>-c and sPUSCH symbol <NUM>-d). Because the DM-RS symbol <NUM>-b has already been transmitted, there may not be a DM-RS trigger for the second two-symbol TTI transmission (e.g., two-symbol TTI <NUM>-c, which may include sPUSCH symbol <NUM>-e and sPUSCH symbol <NUM>-f). Therefore, the UE <NUM> may refrain from transmitting a second DM-RS symbol and DM-RS symbol <NUM>-b may be used for both two-symbol TTI transmissions (e.g., two-symbol TTI <NUM>-b and two-symbol TTI <NUM>-c). Using a single DM-RS symbol for multiple two-symbol TTI transmissions may reduce overhead and increase system efficiency.

In some examples, multiple UEs <NUM> may be scheduled to transmit data (e.g., sPUSCH). In such cases, the configurable delay <NUM> between DM-RS and sPUSCH can be used to position the DM-RS for the respective UEs <NUM> so that they overlap. The configurable delay <NUM> may also be used to separate the respective sPUSCHs. An example of such a transmission scheme is shown in <FIG>. In such cases, two UEs <NUM> (e.g., UEo and UE1) may be scheduled for sPUSCH. As shown by uplink transmission <NUM>-c, the two UEs <NUM> may share a single DM-RS symbol <NUM>-c. One of the UEs <NUM> (e.g., UE0) may be granted (e.g., via uplink resource scheduling conveyed by sPDCCH) a configurable delay equal to zero (e.g. symbol periods) so that the sPUSCH symbols for the UE <NUM> (e.g., sPUSCH symbol <NUM>-g and sPUSCH symbol <NUM>-h which may be included in two-symbol TTI <NUM>-d) are transmitted in the two symbols immediately after the DM-RS symbol <NUM>-c. The other scheduled UE <NUM> (e.g., UE1) may be granted a configurable delay equal to two (e.g., two symbol periods) so that the sPUSCH symbols for the UE <NUM> (e.g., sPUSCH symbol <NUM>-i and sPUSCH symbol <NUM>-j, which may be included in two-symbol TTI <NUM>-e) are transmitted in the third and fourth symbols after DM-RS symbol <NUM>-c. Thus, a UE <NUM> may refrain from transmitting sPUSCH in certain symbols or two-symbol TTIs based on the configurable delay assigned to that UE <NUM>.

In some cases, a DM-RS symbol <NUM> may be included in a two-symbol TTI (e.g., the two-symbol TTI may be self-containing). A self-containing two-symbol TTI may reduce latency and overhead compared to a two-symbol TTI that is not self-containing. Examples of uplink transmissions associated with self-containing two-symbol TTIs are depicted in <FIG>. <FIG>, <FIG> illustrate examples of uplink transmissions <NUM>-a, <NUM>-b, <NUM>-c, <NUM>-d and <NUM>-e that support self-contained uplink for reduced duration transmission time intervals in accordance with various aspects of the present disclosure. Uplink transmissions <NUM>-a, <NUM>-b, <NUM>-c, <NUM>-d, and <NUM>-e may illustrate aspects of an uplink transmission between a UE <NUM>, such as a low latency UE <NUM>, and a base station <NUM>, as described above with reference to <FIG>. Uplink transmissions <NUM> may include two-symbol TTIs <NUM>. In a wireless communications system that uses two-symbol TTIs, there may be one DM-RS symbol (e.g., a DM-RS symbol <NUM>) and one sPUSCH symbol (e.g., sPUSCH symbols <NUM>) per two-symbol TTI (e.g., two-symbol TTI <NUM>). Alternatively, a two-symbol TTI may include sPUSCHs and no DM-RS (e.g., if there is not DM-RS trigger associated with the two-symbol TTI). In another example, DM-RS for multiple UEs <NUM> may be included in a two-symbol TTI (e.g., in one of the symbols of the two-symbol TTI).

Uplink transmission <NUM>-a illustrates an example of a self-containing two-symbol TTI <NUM>-a. Two-symbol TTI <NUM>-a may include a DM-RS symbol <NUM>-a and sPUSCH symbol <NUM>-a for a single UE <NUM>. For example, a UE <NUM> that receives a DM-RS trigger (e.g., in an uplink grant) may transmit DM-RS symbol <NUM>-a in the first symbol of the two-symbol TTI <NUM>-a and transmit sPUSCH symbol <NUM>-a in the second symbol of the two-symbol TTI-a. If the UE <NUM> does not receive a DM-RS trigger, the UE <NUM> (e.g., UE0) may transmit sPUSCH in both symbols of a two-symbol TTI. Such an example is depicted in <FIG>, in which both symbols of two-symbol TTI <NUM>-a convey sPUSCH (e.g., the first symbol conveys sPUSCH symbol <NUM>-c for UEo and the second symbol conveys sPUSCH symbol <NUM>-d for UE0). Thus, the payload for two-symbol TTI <NUM>-b (e.g., one symbol) may be different from the payload for two-symbol TTI <NUM>-a (e.g., two symbols).

In some cases, a configurable delay may be introduced between a DM-RS symbol and sPUSCH symbols. For example, configurable delay <NUM> may be introduced between DM-RS symbol <NUM>-b and two-symbol TTI <NUM>-c, which may include sPUSCH symbol <NUM>-e and sPUSCH symbol <NUM>-f. The configurable delay may be a number of symbol periods, or two-symbol TTIs periods, between a symbol with the DM-RS and the subsequent TTI. The number of symbol periods may include an even or odd integer number. The configurable delay <NUM> may temporally displace the DM-RS symbol <NUM>-e so that the DM-RS symbol is transmitted prior to the symbol that is immediately before the first symbol of the two-symbol TTI <NUM>-c. For example, the configurable delay <NUM> may be selected (e.g., as an integer number of symbols) so that the DM-RS symbol <NUM>-e aligns with the DM-RS symbol of different UE <NUM>. In some cases, the DM-RS symbol <NUM>-e may be part of a two-symbol TTI that includes an empty symbol. In other cases, DM-RS symbol <NUM>-e may be part of a one-symbol TTI.

In some examples, multiple two-symbol TTIs <NUM> may be sent consecutively. For example, in <FIG>, two two-symbol TTIs <NUM> are transmitted back-to-back. The two-symbol TTIs <NUM> may include one or more DM-RS symbols <NUM> and sPUSCH symbols for a UE <NUM> (e.g., UE0). The content of a two-symbol TTI <NUM> may be based on the presence, or absence, of DM-RS trigger(s) in an uplink grant to the UE <NUM>. For example, the first two-symbol TTI <NUM>-c may include both a DM-RS symbol and an sPUSCH symbol (DM-RS symbol <NUM>-c and sPUSCH symbol <NUM>-g) if a DM-RS trigger is received by the UE <NUM> for that particular sPUSCH symbol. The second two-symbol TTI <NUM>-d may include two sPUSCH symbols (e.g., sPUSCH symbol <NUM>-h and sPUSCH symbol <NUM>-i) if a DM-RS trigger is not received for those particular sPUSCH symbols.

In some examples, an uplink grant can introduce a configurable delay (e.g., such as configurable delay <NUM>) to delay the transmission of sPUSCH symbols with respect the DM-RS symbol. An example of such a transmission is shown in <FIG>. In <FIG>, uplink transmission <NUM>-e may include multiple (e.g., two or more) two-symbol TTIs <NUM>. For example, uplink transmission <NUM>-e may include two-symbol TTI <NUM>-e and two-symbol TTI <NUM>-f. Two-symbol TTI <NUM>-e (e.g., the first two-symbol TTI) may include DM-RS symbol <NUM>-d for multiple UEs <NUM> (e.g., UE0 and UE1) and an sPUSCH symbol <NUM>-j for one of the UEs <NUM> (e.g., UE0). DM-RS symbols for different UEs <NUM> may be separated via cyclic offset. Two-symbol TTI <NUM>-f may include sPUSCH symbols (e.g., sPUSCH symbol <NUM>-k and sPUSCH symbol <NUM>-l) for the other UE <NUM> (e.g., UE1).

In the example depicted in <FIG>, the configurable delay may be one (e.g., one symbol period) so that the DM-RS is transmitted in the first symbol in the first two-symbol TTI and sPUSCH symbols for a first UE <NUM> (e.g., UE <NUM>) are transmitted in the two symbols of the second two-symbol TTI. The second symbol of the first two-symbol TTI may be empty (e.g., reserved for another UE <NUM>, such as UE0). Thus, UE1 may transmit DM-RS in the first symbol of two-symbol TTI <NUM>-e and may refrain from transmitting data (e.g., sPUSCH) in the second symbol of two-symbol TTI <NUM>-e. The configurable delay for UEo may be zero so that UE0 may transmit DM-RS in the first symbol of two-symbol TTI <NUM>-c and sPUSCH in the second symbol of two-symbol TTI <NUM>-c.

The UEs <NUM> may be scheduled their respective configurable delays, symbols, and two-symbol TTIs based on buffer size and/or quality of service (QoS) (e.g., the UE <NUM> with the largest buffer size or highest QoS may be scheduled two sPUSCH symbols <NUM>). Or the UEs <NUM> may be assigned their respective symbols and two-symbol TTIs based on the order that scheduling requests from each UE <NUM> arrived at a base station <NUM> (e.g., UE0 may be assigned sPUSCH symbol <NUM>-g because a scheduling request from UEo arrived at the base station <NUM> earlier than a scheduling request from UE1). Although described with reference to two UEs <NUM>, the techniques described herein for multiple UEs <NUM> may be used for any number of UEs <NUM>.

<FIG> illustrates an example of a process flow <NUM> that supports self-contained uplink for reduced duration transmission time intervals in accordance with various aspects of the present disclosure. Process flow <NUM> may include steps or signaling performed by UE <NUM>-c and base station <NUM>-b, which may be examples of a UE <NUM> or base station <NUM> described above with reference to <FIG> and <FIG>. In some examples, a base station <NUM>-b may transmit a two-symbol TTI transmission to a low latency UE <NUM>-c using resources that are also available for legacy transmissions.

At <NUM>, UE <NUM>-c may transmit, and base station <NUM>-b may receive, a scheduling request. The scheduling request may request uplink resources (e.g., time and frequency) to be allocated/scheduled for UE <NUM>-c. A scheduling request may also be referred to as a service request. The scheduling request may include uplink buffer size information, priority level information, and/or a QoS information associated with UE <NUM>-c. At <NUM>, base station <NUM>-b may determine resource allocations (e.g., scheduling) for UE <NUM>-c. In some cases, base station <NUM>-b may determine whether a DM-RS is scheduled to be transmitted in one symbol of a two-symbol TTI sent by UE <NUM>-c. Base station <NUM>-b may determine the resource allocations based on the timing of the scheduling request sent by the UE <NUM>-c, or based on the uplink buffer size information or the QoS information associated with UE <NUM>-c.

At <NUM>, base station <NUM>-b may transmit, and UE <NUM>-c may receive, an uplink grant that includes an uplink resource allocation for UE <NUM>-c. The uplink resource allocation may be received in a downlink control channel (e.g., sPDCCH) during a two-symbol TTI. Alternatively, the uplink resource allocation may be received in a downlink control channel of during TTI that has a longer duration than the two-symbol TTI (e.g., the uplink resource allocation may be received in a downlink control channel during a legacy TTI).

The uplink resource allocation may include an indication of the time and frequency resources assigned for use by UE <NUM>-c for uplink communication. The uplink resource allocation may be associated with two-symbol TTIs (e.g., the uplink resource allocation may include an indication that UE <NUM>-c is to use two-symbol TTIs for uplink). In some cases, the uplink resource allocation may include one or more DM-RS triggers that indicate to UE <NUM>-c that DM-RS is to be sent for particular sPUSCHs. The uplink resource allocation includes an indication of the number of symbol periods between DM-RS symbol and a subsequent TTI (e.g., a two-symbol TTI). For example, the uplink resource allocation may include an indication of a configurable delay.

At <NUM>, UE <NUM>-c may determine the content of one or more two-symbol TTIs based at least in part on the uplink grant. For example, UE <NUM>-c may determine whether DM-RS is scheduled to be transmitted as part of a self-contained two-symbol TTI. In some cases, the determination may be based on uplink resource allocation (e.g., the determination may be based on the presence or absence of a DM-RS trigger in the uplink resource allocation).

At <NUM>, UE <NUM>-c may transmit, and base station <NUM>-c may receive, a self-contained two-symbol TTI. The self-contained two-symbol TTI may be an example of an uplink transmission <NUM> described with reference to <FIG>. The self-contained two-symbol TTI includes DM-RS and may include data (e.g., sPUSCH). For example, both DM-RS and data may be transmitted during the two-symbol TTI if UE <NUM>-c determines that the DM-RS is scheduled. The DM-RS may be transmitted in a first symbol of the two-symbol TTI and the data may be transmitted in a second symbol of the two-symbol TTI. In some examples of such cases, UE <NUM>-c may transmit additional data during a subsequent TTI (e.g., a two-symbol TTI). The subsequent TTI may exclude DM-RS and may be sent according to a configurable delay.

In some cases, UE <NUM>-c may transmit DM-RS in the first symbol of the two-symbol TTI and refrain from transmitting during the second symbol of the two-symbol TTI. In such cases, the second symbol of the two-symbol TTI may be reserved for or available for communications by another UE <NUM>. In some examples, the first symbol of the two-symbol TTI includes DM-RS from multiple UEs <NUM> (e.g., UE <NUM>-c and another UE <NUM>). The DM-RS may be cyclically shifted relative to each other to provide for detection at base station <NUM>-b. In such a scenario, the second symbol may include data from one of the UEs <NUM> and a subsequent twos-symbol TTI may exclude DM-RS.

<FIG> illustrates an example of a transmission timing diagram <NUM> that supports self-contained uplink for reduced duration transmission time intervals in accordance with various aspects of the present disclosure. Transmission timing diagram <NUM> may include steps or signaling performed by a UE <NUM> and base station <NUM>, which may be examples of a UE <NUM> or base station <NUM> described above with reference to <FIG> and <FIG>. Transmission timing diagram <NUM> may include a number of two-symbol TTIs <NUM>. Transmission timing diagram assumes a processing duration of four two-symbol TTIs.

A base station <NUM> may transmit an uplink grant in two-symbol TTI N (e.g., two-symbol TTI <NUM>-a). The uplink grant may include uplink resource allocation scheduling information for two UEs (e.g., UEo and UE <NUM>). Each UE may receive the uplink grant and determine uplink transmission resources based on the resource allocation scheduling information. The uplink grant may include a DM-RS trigger for UEo and a DM-RS trigger for UE1. The uplink grant may also include a DM-RS offset for UE0 and a DM-RS offset for UE1. Responsive to the uplink grant, UE0 may transmit DM-RS in the first symbol of two-symbol TTI N + <NUM> (e.g., two-symbol TTI <NUM>-b) and transmit data (e.g., sPUSCH) in the second symbol of two-symbol TTI N + <NUM> (e.g., two-symbol TTI <NUM>-b). Also responsive to the uplink grant, UE1 may transmit DM-RS in the first symbol of two-symbol TTI N + <NUM> (e.g., two-symbol TTI <NUM>-b) and transmit data in both symbols of two-symbol TTI N + <NUM> (e.g., two-symbol TTI <NUM>-c).

The base station <NUM> may transmit acknowledgments (ACKs) or negativeacknowledgments (NACKs) to both UEs based on the success of reception of the respective data from the UEs. For example, the base station <NUM> may send an ACK to UE0 in two-symbol TTI N + <NUM> + <NUM> (e.g., two-symbol TTI <NUM>-d) if the data in two-symbol TTI N + <NUM> (e.g., two-symbol TTI <NUM>-b) is successfully received. Alternatively, the base station <NUM> may send a NACK to UE0 in two-symbol TTI N + <NUM> + <NUM> (e.g., two-symbol TTI <NUM>-d) if the DMRS and data in two-symbol TTI N + <NUM> (e.g., two-symbol TTI <NUM>-b) is not successfully received. Similarly, the base station <NUM> may send an ACK to UE1 in two-symbol TTI N + <NUM> + <NUM> (e.g., two-symbol TTI <NUM>-e) if the data in two-symbol TTI N + <NUM> (e.g., two-symbol TTI <NUM>-c) is successfully received. Or the base station <NUM> may send a NACK to UE1 in two-symbol TTI N + <NUM> + <NUM> (e.g., two-symbol TTI <NUM>-e) if the data in two-symbol TTI N + <NUM> (e.g., two-symbol TTI <NUM>-c) is not successfully received. Thus, the latency for hybrid automatic repeat request (HARQ) processes for self-contained two-symbol TTIs may be reduced compared to legacy TTIs (e.g., subframe TTIs).

<FIG> shows a block diagram of a wireless device <NUM> that supports self-contained uplink for reduced duration TTIs in accordance with various aspects of the present disclosure. Wireless device <NUM> may be an example of aspects of a UE <NUM> described with reference to <FIG> and <FIG>. Wireless device <NUM> may include receiver <NUM>, UE self-contained uplink manager <NUM> and transmitter <NUM>. Wireless device <NUM> may also include a processor. Each of these components may be in communication with each other.

The receiver <NUM> 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 self-contained uplink for reduced duration TTIs, etc.). In some cases, the receiver <NUM> may receive an uplink resource allocation (e.g., conveyed by a downlink control channel such as sPDCCH). Information may be passed on to other components of the device. The receiver <NUM> may be an example of aspects of the transceiver <NUM> described with reference to <FIG>.

The UE self-contained uplink manager <NUM> may receive an uplink resource allocation that is associated with a two-symbol TTI and determine whether a DM-RS is scheduled to be transmitted in one symbol of the two-symbol TTI as part of the uplink resource allocation. The UE self-contained uplink manager <NUM> may also transmit data or the DM-RS, or both, during the two-symbol TTI based on the determination of whether the DM-RS is scheduled. The UE self-contained uplink manager <NUM> may also be an example of aspects of the UE self-contained uplink manager <NUM> described with reference to <FIG>.

The transmitter <NUM> may transmit signals received from other components of wireless device <NUM>. In some examples, the transmitter <NUM> may be collocated with a receiver in a transceiver module. In some examples, the transmitter <NUM> may transmit two-symbol TTIs such as described herein. The transmitter <NUM> may include a single antenna, or it may include a plurality of antennas.

<FIG> shows a block diagram of a wireless device <NUM> that supports self-contained uplink for reduced duration TTIs in accordance with various aspects of the present disclosure. Wireless device <NUM> may be an example of aspects of a wireless device <NUM> or a UE <NUM> described with reference to <FIG>, <FIG> and <FIG>. Wireless device <NUM> may include receiver <NUM>, UE self-contained uplink manager <NUM> and transmitter <NUM>. Wireless device <NUM> may also include a processor. Each of these components may be in communication with each other.

The receiver <NUM> may receive information which may be passed on to other components of the device. The receiver <NUM> may also perform the functions described with reference to the receiver <NUM> of <FIG>. The receiver <NUM> may be an example of aspects of the transceiver <NUM> described with reference to <FIG>. The transmitter <NUM> may transmit signals received from other components of wireless device <NUM>. In some examples, the transmitter <NUM> may be collocated with a receiver in a transceiver module. The transmitter <NUM> may utilize a single antenna, or it may utilize a plurality of antennas.

The UE self-contained uplink manager <NUM> may be an example of aspects of UE self-contained uplink manager <NUM> described with reference to <FIG>. The UE self-contained uplink manager <NUM> may include uplink resource allocation component <NUM>, DM-RS component <NUM> and DM-RS based transmission component <NUM>. The UE self-contained uplink manager <NUM> may be an example of aspects of the UE self-contained uplink manager <NUM> described with reference to <FIG>.

The uplink resource allocation component <NUM> may receive an uplink resource allocation that is associated with a two-symbol TTI. In some cases, the uplink resource allocation includes an indication of a number of symbol periods between a symbol with the DM-RS and the subsequent TTI. In such cases, additional data may be transmitted according to the indication. In some cases, the uplink resource allocation is received in a downlink control channel (e.g., PDCCH or sPDCCH) during a prior two-symbol TTI. In some cases, the uplink resource allocation is received in a downlink control channel of during TTI that has a longer duration than the two-symbol TTI.

The DM-RS component <NUM> may determine whether a DM-RS is scheduled to be transmitted in one symbol of the two-symbol TTI as part of the uplink resource allocation. In some cases, the DM-RS component <NUM> may determine that the DM-RS is scheduled. In some cases, the DM-RS and the data are transmitted during the two-symbol TTI. The DM-RS based transmission component <NUM> may transmit the data during a second symbol of the two-symbol TTI, transmit data during a subsequent TTI that excludes another DM-RS, and transmit data or the DM-RS, or both, during the two-symbol TTI based on the determination of whether the DM-RS is scheduled. In some cases, the number of symbol periods between the symbol with the DM-RS and the subsequent TTI includes an odd number. In some cases, the transmitting includes transmitting the DM-RS during a first symbol of the two-symbol TTI. In some cases, the transmitting includes transmitting the DM-RS during a first symbol of the two-symbol TTI. In some cases, the first symbol of the two-symbol TTI includes DM-RS transmissions from two or more UE.

<FIG> shows a block diagram of a UE self-contained uplink manager <NUM> which may be an example of the corresponding component of wireless device <NUM> or wireless device <NUM>. That is, UE self-contained uplink manager <NUM> may be an example of aspects of UE self-contained uplink manager <NUM> or UE self-contained uplink manager <NUM> described with reference to <FIG> and <FIG>. The UE self-contained uplink manager <NUM> may also be an example of aspects of the UE self-contained uplink manager <NUM> described with reference to <FIG>.

The UE self-contained uplink manager <NUM> may include DM-RS component <NUM>, DM-RS based transmission component <NUM>, transmission suppression component <NUM>, uplink resource allocation component <NUM> and non DM-RS based transmission component <NUM>. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses).

The DM-RS component <NUM> may determine that a DM-RS is scheduled to be transmitted in one symbol of the two-symbol TTI as part of the uplink resource allocation. In such cases, the DM-RS and the data may be transmitted during the two-symbol TTI. The DM-RS based transmission component <NUM> may transmit the data during a second symbol of the two-symbol TTI, transmit data during a subsequent TTI that excludes another DM-RS, and transmit data or the DM-RS, or both, during the two-symbol TTI based on the determination of whether the DM-RS is scheduled.

The transmission suppression component <NUM> may refrain from transmitting during a second symbol of the two-symbol TTI. In such cases, resources of the second symbol TTI may be available for communications by another device. The uplink resource allocation component <NUM> may receive an uplink resource allocation that is associated with a two-symbol TTI. The non DM-RS based transmission component <NUM> may transmit additional data during a subsequent TTI, where the subsequent TTI excludes another DM-RS.

<FIG> shows a diagram of a system <NUM> including a device that supports self-contained uplink for reduced duration TTIs in accordance with various aspects of the present disclosure. For example, system <NUM> may include UE <NUM>-d, which may be an example of a wireless device <NUM>, a wireless device <NUM>, or a UE <NUM> as described with reference to <FIG>, <FIG> and <FIG>.

UE <NUM>-d may also include UE self-contained uplink manager <NUM>, memory <NUM>, processor <NUM>, transceiver <NUM>, antenna <NUM> and ECC module <NUM>. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses). The UE self-contained uplink manager <NUM> may be an example of a UE self-contained uplink manager as described with reference to <FIG>.

The memory <NUM> may include random access memory (RAM) and read only memory (ROM). The memory <NUM> may store computer-readable, computer-executable software including instructions that, when executed, cause the processor to perform various functions described herein (e.g., self-contained uplink for reduced duration TTIs, etc.). In some cases, the software <NUM> may not be directly executable by the processor but may cause a computer (e.g., when compiled and executed) to perform functions described herein. The processor <NUM> may include an intelligent hardware device, (e.g., a central processing unit (CPU), a microcontroller, an application specific integrated circuit (ASIC), etc.).

The transceiver <NUM> may communicate bi-directionally, via one or more antennas, wired, or wireless links, with one or more networks, as described above. For example, the transceiver <NUM> may communicate bi-directionally with a base station <NUM> or a UE <NUM>. ECC module <NUM> may enable operations using ECCs such as communication using shared or unlicensed spectrum, using reduced TTIs or subframe durations, or using a large number of component carriers.

<FIG> shows a block diagram of a wireless device <NUM> that supports self-contained uplink for reduced duration TTIs in accordance with various aspects of the present disclosure. Wireless device <NUM> may be an example of aspects of a base station <NUM> described with reference to <FIG> and <FIG>. Wireless device <NUM> may include receiver <NUM>, transmitter <NUM> and base station self-contained uplink manager <NUM>. Wireless device <NUM> may also include a processor. Each of these components may be in communication with each other.

The receiver <NUM> 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 self-contained uplink for reduced duration TTIs, etc.). In some cases, the receiver <NUM> may receive two-symbol TTIs from a UE <NUM> such as described herein. Information may be passed on to other components of the device. The receiver <NUM> may be an example of aspects of the transceiver <NUM> described with reference to <FIG>.

The transmitter <NUM> may transmit signals received from other components of wireless device <NUM>. In some cases, the transmitter <NUM> may transmit an uplink resource allocation in a downlink control channel (e.g., PDCCH or sPDCCH). In some examples, the transmitter <NUM> may be collocated with a receiver in a transceiver module. The transmitter <NUM> may include a single antenna, or it may include a plurality of antennas.

The base station self-contained uplink manager <NUM> may transmit an uplink resource allocation that is associated with a two-symbol TTI and determine whether a DM-RS is scheduled to be transmitted in one symbol of the two-symbol TTI as part of the uplink resource allocation. The base station self-contained uplink manager <NUM> may receive data or the DM-RS, or both, during the two-symbol TTI based on the determination of whether the DM-RS is scheduled. The base station self-contained uplink manager <NUM> may also be an example of aspects of the base station self-contained uplink manager <NUM> described with reference to <FIG>.

<FIG> shows a block diagram of a wireless device <NUM> that supports self-contained uplink for reduced duration TTIs in accordance with various aspects of the present disclosure. Wireless device <NUM> may be an example of aspects of a wireless device <NUM> or a base station <NUM> described with reference to <FIG>, <FIG> and <FIG>. Wireless device <NUM> may include receiver <NUM>, base station self-contained uplink manager <NUM> and transmitter <NUM>. Wireless device <NUM> may also include a processor. Each of these components may be in communication with each other.

The base station self-contained uplink manager <NUM> may be an example of aspects of base station self-contained uplink manager <NUM> described with reference to <FIG>. The base station self-contained uplink manager <NUM> may include uplink resource allocation component <NUM>, DM-RS component <NUM> and DM-RS based reception component <NUM>. The base station self-contained uplink manager <NUM> may be an example of aspects of the base station self-contained uplink manager <NUM> described with reference to <FIG>.

The uplink resource allocation component <NUM> may transmit an uplink resource allocation that is associated with a two-symbol TTI. The DM-RS component <NUM> may determine whether a DM-RS is scheduled to be transmitted in one symbol of the two-symbol TTI as part of the uplink resource allocation. In some cases, the uplink resource allocation component <NUM> may determine that the DM-RS is scheduled. In such cases, the DM-RS and the data may be received during the two-symbol TTI.

The DM-RS based reception component <NUM> may receive data or the DM-RS, or both, during the two-symbol TTI based on the determination of whether the DM-RS is scheduled. In some cases, the DM-RS based reception component <NUM> may receive additional data during a subsequent TTI which excludes another DM-RS. The DM-RS based reception component <NUM> may also receive the data during a second symbol of the two-symbol TTI. In some cases, the receiving includes receiving the DM-RS during a first symbol of the two-symbol TTI. In some cases, the receiving includes receiving the DM-RS during a first symbol of the two-symbol TTI, where the DM-RS is associated with a first UE.

<FIG> shows a block diagram of a base station self-contained uplink manager <NUM> which may be an example of the corresponding component of wireless device <NUM> or wireless device <NUM>. That is, base station self-contained uplink manager <NUM> may be an example of aspects of base station self-contained uplink manager <NUM> or base station self-contained uplink manager <NUM> described with reference to <FIG> and <FIG>. The base station self-contained uplink manager <NUM> may also be an example of aspects of the base station self-contained uplink manager <NUM> described with reference to <FIG>.

The base station self-contained uplink manager <NUM> may include DM-RS component <NUM>, DM-RS based reception component <NUM>, uplink resource allocation component <NUM>, DM-RS multiplexing component <NUM>, data multiplexing component <NUM> and non DM-RS based reception component <NUM>. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses).

The DM-RS component <NUM> may determine whether a DM-RS is scheduled to be transmitted in one symbol of the two-symbol TTI as part of the uplink resource allocation. In some cases, the DM-RS component <NUM> may determine that the DM-RS is scheduled. In such cases, the DM-RS and the data may be received during the two-symbol TTI.

The DM-RS based reception component <NUM> may receive data or the DM-RS, or both, during the two-symbol TTI based on the determination of whether the DM-RS is scheduled. The DM-RS based reception component <NUM> may receive additional data during a subsequent TTI which excludes another DM-RS. In some cases, the DM-RS based reception component <NUM> receives the data during a second symbol of the two-symbol TTI. In some cases, the receiving includes receiving the DM-RS during a first symbol of the two-symbol TTI. In some cases, the receiving includes receiving the DM-RS during a first symbol of the two-symbol TTI, where the DM-RS is associated with a first UE.

The uplink resource allocation component <NUM> may transmit an uplink resource allocation that is associated with a two-symbol TTI. The DM-RS multiplexing component <NUM> may receive another DM-RS during the first symbol of the two-symbol TTI, where the other DM-RS is associated with a second UE. The data multiplexing component <NUM> may receive data from the second UE during a second symbol of the two-symbol TTI. The non DM-RS based reception component <NUM> may receive data from the first UE during a subsequent TTI that excludes another DM-RS.

<FIG> shows a diagram of a wireless system <NUM> including a device configured that supports self-contained uplink for reduced duration TTIs in accordance with various aspects of the present disclosure. For example, wireless system <NUM> may include base station <NUM>-d, which may be an example of a wireless device <NUM>, a wireless device <NUM>, or a base station <NUM> as described with reference to <FIG>, <FIG> and <FIG> through <NUM>. Base station <NUM>-d may also include components for bi-directional voice and data communications including components for transmitting communications and components for receiving communications. For example, base station <NUM>-d may communicate bi-directionally with one or more UEs <NUM>.

Base station <NUM>-d may also include base station self-contained uplink manager <NUM>, memory <NUM>, processor <NUM>, transceiver <NUM>, antenna <NUM>, base station communications module <NUM> and network communications module <NUM>. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses). The base station self-contained uplink manager <NUM> may be an example of a base station self-contained uplink manager as described with reference to <FIG>.

The memory <NUM> may include RAM and ROM. The memory <NUM> may store computer-readable, computer-executable software including instructions that, when executed, cause the processor to perform various functions described herein (e.g., self-contained uplink for reduced duration TTIs, etc.). In some cases, the software <NUM> may not be directly executable by the processor but may cause a computer (e.g., when compiled and executed) to perform functions described herein. The processor <NUM> may include an intelligent hardware device, (e.g., a CPU, a microcontroller, an ASIC, etc.).

The transceiver <NUM> may communicate bi-directionally, via one or more antennas, wired, or wireless links, with one or more networks, as described above. For example, the transceiver <NUM> may communicate bi-directionally with a base station <NUM> or a UE <NUM>. However, in some cases the device may have more than one antenna, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

The base station communications module <NUM> may manage communications with other base station <NUM>, and may include a controller or scheduler for controlling communications with UEs <NUM> in cooperation with other base stations <NUM>. For example, the base station communications module <NUM> may coordinate scheduling for transmissions to UEs <NUM> for various interference mitigation techniques such as beamforming or joint transmission. In some examples, base station communications module <NUM> may provide an X2 interface within an LTE/LTE-A wireless communication network technology to provide communication between base stations <NUM>. The network communications module <NUM> may manage communications with the core network (e.g., via one or more wired backhaul links). For example, the network communications module <NUM> may manage the transfer of data communications for client devices, such as one or more UEs <NUM>.

<FIG> shows a flowchart illustrating a method <NUM> for self-contained uplink for reduced duration TTIs in accordance with various aspects of the present disclosure. The operations of method <NUM> may be implemented by a device such as a UE <NUM> or its components as described with reference to <FIG> and <FIG>. For example, the operations of method <NUM> may be performed by the UE self-contained uplink manager as described herein. In some examples, the UE <NUM> may execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively, the UE <NUM> may perform aspects the functions described below using special-purpose hardware.

At block <NUM>, the UE <NUM> may receive an uplink resource allocation that is associated with a two-symbol TTI as described above with reference to <FIG>. In certain examples, the operations of block <NUM> may be performed by the uplink resource allocation component as described with reference to <FIG> and <FIG>.

At block <NUM>, the UE <NUM> may determine whether a DM-RS is scheduled to be transmitted in one symbol of the two-symbol TTI as part of the uplink resource allocation as described above with reference to <FIG>. In certain examples, the operations of block <NUM> may be performed by the DM-RS component as described with reference to <FIG> and <FIG>.

At block <NUM>, the UE <NUM> may transmit data or the DM-RS, or both, during the two-symbol TTI based on the determination of whether the DM-RS is scheduled as described above with reference to <FIG>. In certain examples, the operations of block <NUM> may be performed by the DM-RS based transmission component as described with reference to <FIG> and <FIG>.

<FIG> shows a flowchart illustrating a method <NUM> for self-contained uplink for reduced duration TTIs in accordance with various aspects of the present disclosure. The operations of method <NUM> may be implemented by a device such as a base station <NUM> or its components as described with reference to <FIG> and <FIG>. For example, the operations of method <NUM> may be performed by the base station self-contained uplink manager as described herein. In some examples, the base station <NUM> may execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively, the base station <NUM> may perform aspects the functions described below using special-purpose hardware.

At block <NUM>, the base station <NUM> may transmit an uplink resource allocation that is associated with a two-symbol TTI as described above with reference to <FIG>. In certain examples, the operations of block <NUM> may be performed by the uplink resource allocation component as described with reference to <FIG> and <FIG>.

At block <NUM>, the base station <NUM> may determine whether a DM-RS is scheduled to be transmitted in one symbol of the two-symbol TTI as part of the uplink resource allocation as described above with reference to <FIG>. In certain examples, the operations of block <NUM> may be performed by the DM-RS component as described with reference to <FIG> and <FIG>.

At block <NUM>, the base station <NUM> may receive data or the DM-RS, or both, during the two-symbol TTI based on the determination of whether the DM-RS is scheduled as described above with reference to <FIG>. In certain examples, the operations of block <NUM> may be performed by the DM-RS based reception component as described with reference to <FIG> and <FIG>.

It should be noted that these methods describe possible implementation, and that the operations and the steps may be rearranged or otherwise modified such that other implementations are possible. In some examples, aspects from two or more of the methods may be combined. For example, aspects of each of the methods may include steps or aspects of the other methods, or other steps or techniques described herein. Thus, aspects of the disclosure may provide for self-contained uplink for reduced duration TTIs.

The description herein is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not to be limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different (physical) locations. Also, as used herein, including in the claims, "or" as used in a list of items (for example, a list of items prefaced by a phrase such as "at least one of" or "one or more") indicates an inclusive list such 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).

By way of example, and not limitation, non-transitory computer-readable media can comprise RAM, ROM, electrically erasable programmable read only memory (EEPROM), compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor.

Techniques described herein may be used for various wireless communications systems such as CDMA, TDMA, FDMA, OFDMA, single carrier frequency division multiple access (SC-FDMA), and other systems. The terms "system" and "network" are often used interchangeably. IS-<NUM> Releases <NUM> and A are commonly referred to as CDMA2000 1X, 1X, etc. IS-<NUM> (TIA-<NUM>) is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. A TDMA system may implement a radio technology such as (Global System for Mobile communications (GSM)). An OFDMA system may implement a radio technology such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE <NUM>, IEEE <NUM> (WiMAX), IEEE <NUM>, Flash-OFDM, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunications system (Universal Mobile Telecommunications System (UMTS)). 3GPP LTE and LTE-advanced (LTE-A) are new releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-a, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). The description herein, however, describes an LTE system for purposes of example, and LTE terminology is used in much of the description above, although the techniques are applicable beyond LTE applications.

In LTE/LTE-A networks, including networks described herein, the term evolved node B (eNB) may be generally used to describe the base stations. The wireless communications system or systems described herein may include a heterogeneous LTE/LTE-A network in which different types of eNBs provide coverage for various geographical regions. For example, each eNB or base station may provide communication coverage for a macro cell, a small cell, or other types of cell. The term "cell" is a 3GPP term that can be used to describe a base station, a carrier or component carrier (CC) associated with a base station, or a coverage area (e.g., sector, etc.) of a carrier or base station, depending on context.

Base stations may include or may be referred to by those skilled in the art as a base transceiver station, a radio base station, an access point (AP), a radio transceiver, a NodeB, eNodeB (eNB), Home NodeB, a Home eNodeB, or some other suitable terminology. The geographic coverage area for a base station may be divided into sectors making up only a portion of the coverage area. The wireless communications system or systems described herein may include base stations of different types (e.g., macro or small cell base stations). The UEs described herein may be able to communicate with various types of base stations and network equipment including macro eNBs, small cell eNBs, relay base stations, and the like. There may be overlapping geographic coverage areas for different technologies. In some cases, different coverage areas may be associated with different communication technologies. In some cases, the coverage area for one communication technology may overlap with the coverage area associated with another technology. Different technologies may be associated with the same base station, or with different base stations.

A small cell is a lower-powered base stations, as compared with a macro cell, that may operate in the same or different (e.g., licensed, unlicensed, etc.) frequency bands as macro cells. An eNB may support one or multiple (e.g., two, three, four, and the like) cells (e.g., component carriers (CCs)). A UE may be able to communicate with various types of base stations and network equipment including macro eNBs, small cell eNBs, relay base stations, and the like.

The DL transmissions described herein may also be called forward link transmissions while the UL transmissions may also be called reverse link transmissions. Each communication link described herein including, for example, wireless communications system <NUM> and <NUM> of <FIG> and <FIG> may include one or more carriers, where each carrier may be a signal made up of multiple sub-carriers (e.g., waveform signals of different frequencies). Each modulated signal may be sent on a different subcarrier and may carry control information (e.g., reference signals, control channels, etc.), overhead information, user data, etc. The communication links described herein (e.g., communication links <NUM> of <FIG>) may transmit bidirectional communications using frequency division duplex (FDD) (e.g., using paired spectrum resources) or time division duplex (TDD) operation (e.g., using unpaired spectrum resources). Frame structures may be defined for FDD (e.g., frame structure type <NUM>) and TDD (e.g., frame structure type <NUM>).

Thus, aspects of the disclosure may provide for self-contained uplink for reduced duration TTIs. It should be noted that these methods describe possible implementations, and that the operations and the steps may be rearranged or otherwise modified such that other implementations are possible. In some examples, aspects from two or more of the methods may be combined.

The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a digital signal processor (DSP), an ASIC, an field programmable gate array (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. Thus, the functions described herein may be performed by one or more other processing units (or cores), on at least one integrated circuit (IC). In various examples, different types of ICs may be used (e.g., Structured/Platform ASICs, an FPGA, or another semicustom IC), which may be programmed in any manner known in the art. The functions of each unit may also be implemented, in whole or in part, with instructions embodied in a memory, formatted to be executed by one or more general or application-specific processors.

The words "module," "mechanism," "element," "device," "component", and the like may not be a substitute for the word "means. " As such, no claim element is to be construed as a means plus function unless the element is expressly recited using the phrase "means for.

Claim 1:
A method of wireless communication performed by a user equipment, UE, the method comprising:
receiving an uplink resource allocation that is associated with a two-symbol transmission time interval, TTI, the uplink resource allocation comprising an indication of a number of symbol periods between a symbol with a demodulation reference signal, DM-RS and a subsequent two-symbol TTI scheduled for data;
determining that a demodulation reference signal, DM-RS, is scheduled to be transmitted in one symbol of the two-symbol TTI as part of the uplink resource allocation; and
transmitting the DM-RS in the one symbol of the two-symbol TTI and data in the subsequent two-symbol TTI according to the uplink resource allocation.