Patent Description:
These systems may be capable of supporting communication with multiple UEs by sharing the 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., a Long Term Evolution (LTE) system). 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 may transmit information to one or more UEs using a transmission time interval (TTI) that is reduced in length. Such a TTI may be referred to as a shortened TTI (sTTI), and a UE receiving information in an sTTI may be a low latency UE. An sTTI may be divided into a number of blocks across a system bandwidth. The blocks may be allocated to one or more UEs by a base station. The base station may transmit control information or a control message in a first portion of the block to provide resource allocations for UEs. A low latency UE may attempt to decode the control information in the block. As sTTIs become shorter, it is ever more important to reduce the control overhead. Thus, it is desirable to efficiently communicate control information, and minimize the amount of processing time required for a UE to receive and decode the control information. Furthermore, a configuration of the blocks should be flexible to account for different scenarios. Document 3GPP, R1-<NUM> discloses design details to enable multiplexing of sPDCCH and data over each sTTI. Document 3GPP, R1-<NUM> discloses sharing DMRS REs between sPDCCH and sPDSCH. Document <CIT> discloses a method and an apparatus for performing communication in a wireless communication system. A control channel element is configured by using a resource element group in the same symbol of a resource block. The resource element group includes a plurality of resource elements in the same symbol. The resource block is transmitted in units of sTTIs which is set to be shorter than TTI. A control channel corresponding to the control channel element, and a data channel scheduled by the control channel are configured. The control channel and the data channel are transmitted in different frequency bands. Data is transmitted through the data channel.

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.

In an aspect of the disclosure, a method, an apparatus, and a computer program product are provided.

In some aspects, the method may be performed by a user equipment (UE), and may include identifying a resource block set that includes a data region and a control region, wherein the resource block set spans a portion of a system bandwidth in a shortened transmission time interval (sTTI), wherein the sTTI includes three symbols, wherein the control region occupies the three symbols and includes control information for the UE for the sTTI, and wherein the control region and the data region are frequency division multiplexed; and obtaining content in the sTTI based at least in part on the control information.

In some aspects, the apparatus may include a memory and at least one processor coupled to the memory. The at least one processor may be configured to identify a resource block set that includes a data region and a control region, wherein the resource block set spans a portion of a system bandwidth in a shortened transmission time interval (sTTI), wherein the sTTI includes three symbols, wherein the control region occupies the three symbols and includes control information for the apparatus for the sTTI, and wherein the control region and the data region are frequency division multiplexed; and obtain content in the sTTI based at least in part on the control information.

In some aspects, the apparatus may include means for identifying a resource block set that includes a data region and a control region, wherein the resource block set spans a portion of a system bandwidth in a shortened transmission time interval (sTTI), wherein the sTTI includes three symbols, wherein the control region occupies the three symbols and includes control information for the apparatus for the sTTI, and wherein the control region and the data region are frequency division multiplexed; and means for obtaining content in the sTTI based at least in part on the control information.

In some aspects, the computer program product may include a non-transitory computer-readable medium storing computer executable code. The code may include code for identifying a resource block set that includes a data region and a control region, wherein the resource block set spans a portion of a system bandwidth in a shortened transmission time interval (sTTI), wherein the sTTI includes three symbols, wherein the control region occupies the three symbols and includes control information for the sTTI, and wherein the control region and the data region are frequency division multiplexed; and code for obtaining content in the sTTI based at least in part on the control information.

Aspects generally include a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, wireless communication device, base station, and processing system as substantially described herein with reference to and as illustrated by the accompanying drawings and specification.

Control channels for low latency transmissions may be designed, mapped, and communicated to decrease signaling overhead and to increase the availability of resources for low latency data channels. Data channels using reduced length transmission time intervals (TTIs) (e.g., including a shortened TTI (sTTI)) may encounter a number of challenges, including the need to efficiently support multiple low latency UEs, as well as legacy UEs, while allowing for the efficient reception and decoding of control information. An sTTI may include multiple resource management blocks for downlink transmissions of data. Certain resources within the sTTI may have already been allocated for other types of transmission. Such non-low latency transmissions that may be scheduled within the sTTI may include legacy data transmissions in a physical downlink control channel (PDSCH) within a portion of the system bandwidth also used by the low latency UEs, narrowband internet-of-things (NB-IOT) type transmission, or common signals, such as a cell-specific reference signal (CRS), primary synchronization signal (PSS), secondary synchronization signal (SSS), or physical broadcast channel (PBCH), or other signals reserved by higher level signaling, such as radio resource control (RRC) signaling.

Efficient coexistence between low latency and non-low latency transmissions may increase capacity and transmission efficiency. A control region may be located at the beginning of a resource management block, and a UE may receive and decode control information received in the control region to determine that the data region of the resource management block has been allocated for that UE. Mechanisms to provide for efficient reception and decoding of this control information are desired. In addition, reducing the size of the control region, or otherwise maximizing the size of the data region of the resource management block relative to the control region, or even eliminating one or more of the control regions from one or more of the resource management blocks of the sTTI to minimize the impact of control overhead are desired.

In some aspects, a UE may identify a resource management block based at least in part on a resource management block configuration indicated by a base station. The resource management block may span a portion of a system bandwidth in an sTTI. The UE may identify a resource block set that is a self-contained subset of the resource management block. The resource block set may include control information for the UE for the sTTI. The UE may use the control information to locate content, intended for the UE, at least partially within a data region of the sTTI.

Aspects of the disclosure introduced above are described below in the context of a wireless communications system. Resource allocation diagrams and resource structures are then illustrated to describe aspects of the disclosure. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to downlink control channel structure for low latency communications.

<FIG> illustrates an example of a wireless communications system <NUM>, 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 a LTE (or LTE-Advanced) network.

Each base station <NUM> may provide communication coverage for a respective geographic coverage area <NUM>. Communication links <NUM> shown in wireless communications system <NUM> may include UL transmissions from a UE <NUM> to a base station <NUM>, or DL transmissions, from a base station <NUM> to a UE <NUM>. A UE <NUM> may also be referred to as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology. A UE <NUM> 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, or the like.

In some cases, a base station <NUM> and a user equipment (UE) <NUM> may communicate using more than one carrier. Each aggregated carrier is referred to as a component carrier (CC). Each component can have a bandwidth of, e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM>. In some cases, the number of CCs can be limited to, e.g., a maximum of five <NUM> carriers, giving maximum aggregated bandwidth is <NUM>. In frequency division duplexing (FDD), the number of aggregated carriers can be different in downlink (DL) and uplink (UL). The number of UL component carriers may be equal to or lower than the number of DL component carriers. The individual component carriers can also be of different bandwidths. For time division duplexing (TDD), the number of CCs as well as the bandwidths of each CC will normally be the same for DL and UL. Component carriers may be arranged in a number of ways. For example, a carrier aggregation (CA) configuration may be based at least in part on contiguous component carriers within the same operating frequency band, i.e., called intra-band contiguous CA. Non-contiguous allocations can also be used, where the component carriers may be either be intra-band, or inter-band.

These systems may be capable of supporting communication with multiple UEs by sharing the 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 communications system may include a number of base stations, each simultaneously supporting communication for one or more multiple communication devices, which may be otherwise known as a UE.

A base station <NUM> may communicate with one or more of UEs <NUM> using low latency transmissions, for example using sTTIs. An sTTI may be divided into a number of resource management blocks, one or more of which may include a control region, also referred to as a resource block set. The control region may include a downlink grant for a low latency UE <NUM>, for example indicating a data region of the resource management block is for the UE <NUM> to receive data. In some aspects, the base station <NUM> may indicate a resource management block configuration to the UE <NUM> (e.g., during RRC connection configuration). The resource management block configuration may identify a plurality of resource management blocks that span at least a portion of system bandwidth and are allocated in an sTTI. The UE <NUM> may identify the resource management block based at least in part on the resource management block configuration indicated by the base station <NUM>. The UE <NUM> may identify a resource block set (e.g., a control region) that is a self-contained subset of the resource management block. The resource block set may include control information for the sTTI (and/or one or more other sTTIs). For example, the base station <NUM> may transmit control information for the sTTI in the resource block set. The UE <NUM> may use the control information to locate content, intended for the UE <NUM>, at least partially within a data region of the sTTI.

In some aspects, a downlink grant transmitted in the control region of a resource management block may be both for the resource management block in which the downlink grant is sent by a base station <NUM> (or received at a UE <NUM>) and for a second resource management block within the same TTI. In particular, the downlink grant may include an indication (e.g., a field made up of a number of bits that is one less than the total number of resource management blocks in the TTI) to inform the UE <NUM> that the downlink grant, in addition to being for data to be received by the UE <NUM> in a data region of the resource management block, is also for the UE <NUM> to receive data in a data region of one or more of the other resource management blocks in the TTI.

In addition to a downlink grant in a control region of the TTI, the control region may include one or more uplink grants. One of the uplink grants may be for the same UE <NUM> as the downlink grant. Other uplink grants may be for different UEs <NUM> than the downlink grant. The downlink grant may be at the beginning of the control region, against a first boundary of the control region, and the one or more uplink grants may be at the end of the control region, against a second boundary of the control region. The size of the control region may be large enough so that, for the different possible aggregation levels, uplink grants and the downlink grant do not overlap in the control region. An unused portion of the control region, for example for lower aggregation levels, may be reallocated to the data region. An indication of the start of the uplink grants may be provided in the downlink grant of the control region so that, in conjunction with knowledge by the UE <NUM> of the end of its downlink grant, UE <NUM> may identify the reallocated data region within the control region.

Other examples are possible and may differ from what was described in connection with <FIG>.

<FIG> illustrates an example of a wireless communications system <NUM> for downlink control channel structures for low latency communications, in accordance with various aspects of the present disclosure. Wireless communications system <NUM> includes one or more base stations <NUM>-a and UEs <NUM>-a, which may be examples of aspects of a UE <NUM> as described with reference to <FIG>. Base station <NUM>-a may transmit resource allocations and other control information in one or more shortened physical downlink control channel (sPDCCH) transmissions to UE <NUM>-a. The resource allocations may include one or both of downlink grants and uplink grants of resources for transmission of downlink data (e.g., in a shortened physical downlink shared channel (sPDSCH)) and uplink data (e.g., in a shortened physical uplink shared channel (sPUSCH)) for UE <NUM>-a. Wireless communications system <NUM> may support non-low latency communication <NUM> and a low latency communication <NUM>. Resources for low latency communication <NUM> may be time division multiplexed and/or frequency division multiplexed with non-low latency communication <NUM>.

An sTTI for low latency communications may have multiple resource management blocks, which may span the whole system bandwidth or a portion of the system bandwidth. The resource management blocks may have the same or different sizes in frequency. Each resource management block may be allocated for a single UE or multiple UEs. The UEs may access one, multiple, or all of the resource management blocks of the sTTI, depending on a resource management block configuration. The resource management block structure used may be defined by higher level signaling (e.g., in an RRC connection configuration message), for example for a semi-static configuration.

A resource management block may have an sPDCCH associated with the resource management block. In some aspects, the sPDCCH may be referred to as a control region or a resource block set. The sPDCCH may be embedded in the resource management block (e.g., may be self-contained within the resource management block). The sPDCCH may be at the beginning of the resource management block (e.g., in the first one or more symbols of the resource management block) to enable early decoding of the sPDCCH in the resource management block. The sPDCCH may span the bandwidth of the resource management block, or may occupy less than the full bandwidth of the resource management block, with additional signaling included above (e.g., at a higher frequency) and/or below (e.g., at a lower frequency) the resource elements occupied by the sPDCCH in the resource management block.

In some cases, an sPDCCH may allocate an sPDSCH for a low latency UE to a resource management block that has already been allocated to a PDSCH for some other UEs (e.g., legacy UEs) in a TTI. The TTI may overlap in whole or in part with at least one sTTI. That is, a PDSCH allocation of a TTI may overlap in whole or in part with a resource management block of an sTTI. A transmission with a PDCCH (e.g., which may be referred to as a legacy or regular PDCCH) for a TTI may include an indication of the PDSCH resource allocation within the TTI. For example, a PDSCH indicated by the PDCCH may be allocated to a set of frequency resources. A low latency UE may be configured to monitor for such PDCCHs (e.g., receive and decode legacy PDCCHs) in addition to sPDCCHs. The low latency UE may thus receive and decode the indication in the PDCCH and identify the PDSCH resource allocation.

The low latency UE may also receive an sPDCCH identifying an sPDSCH of a resource management block of an sTTI for the low latency UE, the resource management block also including the regular or legacy PDSCH resource allocation. The low latency UE, having received the indication for the PDSCH, may determine a location of the PDSCH within the sTTI. Based at least in part on the indication, the low latency UE may then determine that the sPDSCH associated with the sPDCCH that the low latency UE has received, for example based at least in part on a downlink grant in the sPDCCH, is frequency division multiplexed with the regular or legacy PDSCH. Thus, the low latency UE may receive low latency data in an sPDSCH even in the presence of a legacy PDSCH resource allocation within the sTTI be monitoring for and identifying an indicator in the legacy or regular PDCCH.

In other cases, an sPDCCH for one resource management block within an sTTI for a UE may include a downlink grant for one or more additional resource management blocks within the sTTI for the same UE. For example, as described above, the sPDCCH may be in the first portion of the sTTI block (e.g., in the first symbol of the sTTI) at a predefined location within the resource management block of the sTTI. A low latency UE may monitor the control region (e.g., the sPDCCH) for each sTTI resource management block to determine whether a downlink grant of resources has been sent (e.g., from a serving base station <NUM>-a) in the sPDCCH to the low latency UE. A low latency UE may search for both uplink and downlink grants in the sPDCCH. In some examples, a two stage grant for the low latency UE may be used, where the first stage grant, received in messaging sent during a time interval prior to the sTTI, specifies an aggregation level associated with the resource management blocks of the sTTI.

As described above, an sPDCCH may be positioned at the beginning of a resource management block of an sTTI. In addition, a downlink grant of the sPDCCH may be positioned at the beginning of the sPDCCH. By providing the downlink grant for a low latency UE in a same position of each sPDCCH, a search space for the low latency UE may be reduced. In some examples, if a low latency UE searches for a control message, for example a downlink grant of resources, for that UE in an sPDCCH, and successfully identifies such a downlink grant is present, the low latency UE may infer that the associated sPDSCH of that resource management block is allocated for that low latency UE. Thus, the low latency UE may efficiently identify the sPDSCH allocated to that UE.

In addition, the downlink grant may include one or more bits to indicate other resource management blocks of the sTTI that include an sPDSCH for that same low latency UE. The one or more bits may be, for example, resource assignment information. Each of the one or more bits may indicate whether or not a resource management block is allocated for the same low latency UE. For example, where an sTTI includes three resource management blocks, two bits in the downlink grant in an sPDSCH of one resource management block may be used to indicate whether the downlink grant is for any of the other three resource management blocks for the low latency UE. Downlink grants in other of the resource management blocks may be for other low latency UEs, and may likewise indicate that the sPDSCH in the resource management block containing the sPDCCH with the downlink grant is for that other low latency UE, and one or more bits (e.g., two bits for three resource management blocks), used to indicate whether any of the other resource management blocks are for the other low latency UE. The bits may be appropriately indexed and the resource management block to which they relate based at least in part on a position of the resource management block in which the one or more bits of the downlink grant appear. The above-described procedure may efficiently indicate downlink grants at least in part because a low latency UE may only need to perform a blind decode in a fixed position of the sPDCCH within the resource management block, and a number of blind decodes used to determine the downlink grant may be limited to a number of resource management blocks configured by a base station <NUM>-a (e.g., cell) in the sTTI.

As described above, a downlink grant may have a position at the beginning of an sPDCCH. In some cases, one or more uplink grants for low latency UEs may be positioned in an sPDSCH of an sTTI that already contains a downlink grant for a low latency UE, where the uplink grant may be for a different low latency UE than the low latency UE that the downlink grant is for. As described above, a first stage grant may specify an aggregation level. The one or more uplink grants may be sent at the specified aggregation level. Where other aggregation levels are specified, the uplink grants may be sent according to other specified aggregation levels.

The uplink grants of an sPDCCH already containing a downlink grant may be separated from the downlink grants. For example, the downlink grants may be transmitted at the beginning of the sPDCCH control region, and the uplink grants may be sent at the end of the sPDCCH control region. As used herein, the sPDCCH control region may be a virtual control region, for example meaning that the resource elements of the sPDCCH may not all be adjacent in the time-frequency domain. The downlink and uplink grants of an sPDCCH may be separated at least in part so that the downlink and uplink grant search spaces do not overlap. Providing the downlink grant at a fixed position relative to a boundary of the sPDCCH control region, and uplink grants at a fixed position relative to another boundary of the sPDCCH control region may reduce the number of blind decode attempts for a low latency UE. In addition, because a downlink grant may be received at a set or predetermined position that is separated from a search space for the one or more uplink grants, UE <NUM>-a may begin to decode the downlink grant prior to completing a blind decoding process for the uplink grants. In some cases, downlink grant processing and uplink grant blind decoding may proceed in parallel, increasing efficiency by decreasing the amount of time needed for UE <NUM>-a to receive and process an sPDCCH.

A position of each of the uplink grants to be transmitted in an sPDCCH may be determined by a transmitting base station <NUM>-a based at least in part on the uplink grant aggregation level. As described above, base station <NUM>-a may transmit an indication of the uplink grant aggregation level to a low latency UE in a prior grant message. The base station <NUM>-a may statically define uplink grant locations for each of multiple aggregation levels. In other examples, multiple uplink grant locations may be defined for a particular aggregation level. Multiple uplink grant locations may result in a greater number of blind decoding attempts by receiving UE <NUM>-a since there are an increased number of potential uplink grant locations for the UE <NUM>-a.

In some examples, the size of the sPDCCH control region may be sized at least large enough to accommodate a nominal level of grants and aggregation levels without overlap of the downlink grants and uplink grants at the various aggregation levels. As such, a portion of the sPDCCH control region may be unused. The size of the unused portion of the sPDCCH control region may depend on a number of uplink grants and the aggregation level for a particular sPDCCH. This unused sPDCCH control region may be repurposed by including an indication in the downlink grant of the sPDCCH (e.g., an sPDCCH rate matching information field) that indicates the start of the uplink grants in the sPDCCH. The UE <NUM>-a that holds the downlink grant may rate match the sPDSCH data region around the downlink grant and uplink grants, if any, to use this otherwise unallocated portion of the sPDCCH as an additional portion of the sPDSCH. The size of this indicator may provide the number of available positions to start the uplink grans in the sPDCCH. For example, where the indictor includes three bits, one of eight possible positions for the start of the uplink grants may be indicated.

<FIG> illustrates an example of a resource allocation diagram <NUM> for downlink control channel structures for low latency communications, in accordance with various aspects of the present disclosure. Resource allocation diagram <NUM> shows a system bandwidth <NUM>, and two sTTIs: sTTI <NUM> and sTTI <NUM>. sTTI <NUM> and sTTI <NUM> may be examples of low latency communication <NUM> described with reference to <FIG>. In this example, each sTTI is associated with two resource management blocks, resource management block <NUM> and resource management block <NUM>. The resource management blocks <NUM> and <NUM> need not necessarily span the entire system bandwidth <NUM>. For example, unallocated region <NUM> and unallocated region <NUM> in sTTI <NUM> and sTTI <NUM>, respectively, may be within the system bandwidth, but not allocated as a low latency resource management block.

PDCCH <NUM>, which in some examples may be included at the start of a subframe, may be transmitted by a base station <NUM> for a TTI associated with that subframe. PDCCH <NUM>, which may be a legacy or otherwise regular PDCCH, may allocate resources within the TTI. In particular, in resource allocation diagram <NUM>, PDCCH <NUM> may allocate PDSCH <NUM>. PDCCH <NUM> may include a control message, receivable by a low latency UE, indicating the allocation of PDSCH <NUM> within the system bandwidth <NUM>. PDSCH <NUM> may have a duration of <NUM> in some examples. Base station <NUM> may allocate resource management block <NUM> and resource management block <NUM> of sTTI <NUM> to a low latency UE, UE A; resource management block <NUM> of sTTI <NUM> to a low latency UE, UE B; and resource management block <NUM> of sTTI <NUM> to a low latency UE, UE C. The base station <NUM> may include sPDCCH <NUM> (e.g., a control region or resource block set) allocating resources (e.g., by including a first DL grant in the sPDCCH <NUM>) to sPDSCH <NUM> for UE A in a control region of resource management block <NUM> of sTTI <NUM>. In addition, sPDCCH <NUM> may allocate resources (e.g., by including a second DL grant in the sPDCCH <NUM>) to sPDSCH <NUM> for UE A in a control region of resource management block <NUM> of sTTI <NUM>. In this example, base station <NUM> may frequency division multiplex sPDSCH <NUM> with PDSCH <NUM>, such that an sPDSCH <NUM> includes portions both above and below PDSCH <NUM> in frequency. The base station <NUM> may provide a control message, for example an indication, in PDCCH <NUM> that it has allocated PDSCH <NUM> to UE A. Receiving UE A may then monitor for and read the indication in PDCCH <NUM> that PDSCH <NUM> has an allocation, so that UE A, after receiving the downlink grant in sPDCCH <NUM>, receive data in the sPDSCH <NUM> data region on either side of PDSCH <NUM>.

In sTTI <NUM>, sPDCCH <NUM> may allocate resources for sPDSCH <NUM> in resource management block <NUM>, and sPDCCH <NUM> may allocate resources for sPDSCH <NUM> in resource management block <NUM>. In this example, base station <NUM> may frequency division multiplex both sPDCCH <NUM> and sPDSCH <NUM> with PDSCH <NUM>, such that sPDCCH <NUM> includes portions both above and below PDSCH <NUM> in frequency, and sPDSCH <NUM> includes portions both above and below PDSCH <NUM> in frequency. Receiving UE C, monitors for and receives the indication in PDCCH <NUM> that PDSCH <NUM> has an allocation with sTTI <NUM>. UE C then monitors for and receives the control message of sPDCCH <NUM> to determine that UE C has an allocation of sPDSCH <NUM> and receives data in the sPDSCH <NUM> data region on either side of PDSCH <NUM>.

Similarly, an sPDCCH and/or sPDSCH may be frequency division multiplexed around other signals transmitted during sTTI <NUM> and sTTI <NUM> as illustrated for resource allocation diagram <NUM>. In one example, a narrowband internet-of-things (NB-IOT) transmission <NUM> may be reserved to be sent during sTTI <NUM> and sTTI <NUM> by RRC signaling. Base station <NUM> may frequency division multiplex (or rate match) around NB-IOT transmission <NUM>. In other example, one or more resource management blocks may be reserved for a common signal, for example a CRS, PSS, SSS, or PBCH, or other signals reserved by higher level signaling, such as RRC signaling.

As described above, the control message in the legacy PDCCH in one TTI may identify a data region, such as a PDSCH or NB-IOT, or common signaling, such as PSS, SSS, CRS, or PBCH, that a low latency UE (or UE <NUM>) can use to identify a resource allocation in an sTTI containing one or more resource management blocks allocated to the low latency UE. The low latency UE may then receive low latency data, for example in a PDSCH, of a data region of one or more of the resource management blocks, where the data is frequency domain multiplexed with the data region identified by the control message in the legacy PDCCH.

<FIG> illustrates an example of a resource allocation diagram <NUM> for downlink control channel structures for low latency communications, in accordance with various aspects of the present disclosure. Resource allocation diagram <NUM> includes one of sTTI <NUM> having a system bandwidth <NUM>. sTTI <NUM> may represent an sTTI within a legacy TTI, or a separate TTI. In some examples, and as may be the case with other sTTI described here, sTTI <NUM> may be of different durations, for example a single symbol period, two symbol periods, three symbol periods, a single slot width associated with a legacy TTI, etc. In this example, sTTI <NUM> includes four resource management blocks: resource management block <NUM> and resource management block <NUM> for UE A, and resource management block <NUM> and resource management block <NUM> for UE B.

A base station <NUM> may generate a downlink grant <NUM> to be included in an sPDCCH <NUM>, the control region of resource management block <NUM>. The sPDCCH <NUM> may be, for example, in a first symbol period of the resource management block <NUM>. The downlink grant <NUM> may be for an sPDSCH <NUM> in a data region of the resource management block <NUM> that contains the downlink grant. The downlink grant may also be for a second sPDSCH, sPDSCH <NUM>, in a data region of resource management block <NUM> that are also for UE A, to be jointly used to receive data at UE A based at least in part on the control information of downlink grant <NUM>. In some aspects, sPDCCH <NUM> (e.g., a control region of resource management block <NUM>) may be referred to as a resource block (RB) set <NUM>.

A base station <NUM> may also generate a second downlink grant <NUM> to be included in an sPDCCH <NUM>, the control region of resource management block <NUM>. The second downlink grant <NUM> may be for the sPDSCH <NUM> of the resource management block <NUM>, and may also be for the sPDSCH for resource management block <NUM>. In some aspects, sPDCCH <NUM> (e.g., a control region of resource management block <NUM>) may be referred to as a resource block set <NUM>.

For both downlink grants, one or more bits in each of downlink grant <NUM> and downlink grant <NUM> may be generated by a transmitting base station <NUM> to indicate other resource management blocks of the sTTI that include an sPDSCH for that same low latency UE. In this example, sTTI <NUM> includes four resource management blocks. Downlink grant <NUM> for a UE A may thus include three bits to indicate whether the downlink grant <NUM> is for any of the other three resource management blocks for UE A.

In one example, the bits of the indication may make up or be a part of a resource allocation field in the downlink grant <NUM>. In other examples, the bits of the indication may be included at another position in an sPDCCH, such as sPDCCH <NUM>, or elsewhere within the control region of a resource management block, such as resource management block <NUM>. The first bit of the indication may be associated with resource management block <NUM>, the second bit may be associated with resource management block <NUM>, and the third bit may be associated with resource management block <NUM>. The receiving UEs, UE A and UE B may infer the relationship between the bits and the resource management blocks. For example, the first bit may be associated with the first resource management block of the sTTI <NUM> that does not contain the downlink grant having the bits of the indication, and so on. In the example shown in resource allocation diagram <NUM> for sTTI <NUM>, in downlink grant <NUM> the third bit of the indication identifies the fourth resource management block <NUM> as for UE A. In downlink grant <NUM>, the second bit of the indication identifies the second resource management block <NUM> as for UE B.

The above-described procedure may efficiently indicate downlink grants at least in part because a low latency UE may only need to perform a blind decode in a fixed position of the sPDCCH within the resource management block, and a number of blind decodes used to determine the downlink grant may be limited to a number of resource management blocks configured by a base station (e.g., cell) in the sTTI. Furthermore, the maximum number of bits in the indication of the downlink grant may also be limited to the number of resource management blocks of the sTTI minus one.

In some aspects, a base station <NUM> may indicate a resource management block configuration to a UE <NUM> (e.g., during RRC connection configuration). The resource management block configuration may identify a plurality of resource management blocks (e.g., resource management block <NUM>, resource management block <NUM>, resource management block <NUM>, resource management block <NUM>, and/or the like) that span at least a portion of system bandwidth <NUM> and are allocated in an sTTI <NUM>. The UE <NUM> may identify a resource management block <NUM> based at least in part on the resource management block configuration indicated by the base station <NUM>. The UE <NUM> may identify a resource block set <NUM> that is a self-contained subset of the resource management block <NUM>. The resource block set <NUM> may include control information for the sTTI <NUM> (and/or one or more other sTTIs). For example, the resource block set <NUM> may be used to communicate a downlink grant <NUM>. The UE <NUM> may use the control information to locate content, intended for the UE <NUM>, at least partially within a data region of the sTTI <NUM>.

<FIG> illustrate examples of resource allocation diagrams <NUM> and <NUM> for downlink control channel structures for low latency communications, in accordance with various aspects of the present disclosure.

Each of resource allocation diagrams <NUM> and <NUM> show a resource management block <NUM> for an sTTI <NUM>, where the resource management block <NUM> includes a control region including sPDCCH <NUM> and a data region including sPDSCH <NUM> for UE A that is indicated by sPDCCH <NUM>. The sPDCCH <NUM> may be or include one or more aspects of sPDCCH <NUM>, sPDCCH <NUM>, sPDCCH <NUM>, sPDCCH <NUM>, and sPDCCH <NUM>. The sPDCCH <NUM> includes at least one downlink grant <NUM> for a UE A. Some examples of an sPDCCH <NUM> may include one more uplink grants for one or more UEs, which may also include an uplink grant for UE A. The examples of resource allocation diagrams <NUM> and <NUM> include uplink grant <NUM> for UE A, uplink grant <NUM> for UE B, uplink grant <NUM> for UE C. In some aspects, sPDCCH <NUM> (e.g., a control region of resource management block <NUM>) may be referred to as a resource block set <NUM>.

As illustrated in resource allocation diagrams <NUM> and <NUM>, a downlink grant <NUM> may be at the beginning of the control region, sPDCCH <NUM>, at a position at a first boundary of the sPDCCH <NUM> control region. The uplink grants may be clustered at the end of the control region, sPDCCH <NUM>. The uplink grants may be transmitted by a base station <NUM> in sPDCCH <NUM> of resource management block <NUM> according to one of multiple different aggregation levels for UE A. In some examples, the aggregation level for UE A may have been indicated in a previously transmitted grant from base station <NUM>. For example, a two-stage grant configuration may be used, such that the first grant in a previous transmission (e.g., a previous sTTI or TTI, such as a PDCCH in a previouslyreceived TTI) may include the aggregation level for UE A, and the second grant may be the downlink grant <NUM>. The uplink grant <NUM>, uplink grant <NUM>, and uplink grant <NUM> may be at the end of sPDCCH <NUM>, with the uplink grant <NUM> for UE A at the end of sPDCCH <NUM> and located at a position at a second boundary of the sPDCCH <NUM> control region. Each of uplink grant <NUM> and uplink grant <NUM> may be at positions adjacent the uplink grant <NUM> for UE A. A size of sPDCCH <NUM> may be large enough such that for any aggregation level that can be indicated for UE A, the downlink grant <NUM> and multiple uplink grants do not overlap if the downlink grant <NUM> is at the beginning of sPDCCH <NUM> and the uplink grants are positioned at the end of sPDCCH <NUM>.

The configuration of downlink grants at the beginning of sPDCCH <NUM> and uplink grants at the end of sPDCCH <NUM>, may reduce the number of blind decode attempts for a UE. For example, one downlink grant for a UE may be at the beginning of sPDCCH <NUM>. If an attempted blind decode at the beginning of sPDCCH is unsuccessful, the UE knows that the sPDSCH <NUM> is not for that UE.

As illustrated in resource allocation diagram <NUM>, a portion of the control region for sPDCCH <NUM> (e.g., a portion of RB set <NUM>) may be reallocated to be a part of data region for sPDSCH <NUM>, recapturing unused control overhead from sPDCCH <NUM>. Thus, reallocated sPDSCH <NUM> may be reallocated from a portion of the sPDCCH <NUM>-a between downlink grant <NUM>-a and the uplink grants, specifically an uplink grant <NUM>-a for UE B. The size of reallocated sPDSCH <NUM> may depend in part on the aggregation level. The resources of sPDCCH <NUM>-a that are to be used for reallocated sPDSCH <NUM> may be signaled in the downlink grant <NUM>-a. In particular, an indication may identify the start of the uplink grant region, which may include uplink grant <NUM>-a, uplink grant <NUM>-a, and uplink grant <NUM>-a for sPDCCH <NUM>-a. In some examples, the indication may be rate matching information field, as further described below.

In some aspects, a base station <NUM> may indicate a resource management block configuration to a UE <NUM>. The resource management block configuration may identify a plurality of resource management blocks that span at least a portion of system bandwidth and are allocated in an sTTI <NUM>. The UE <NUM> may identify a resource management block <NUM>, of the plurality of resource management blocks, based at least in part on the resource management block configuration indicated by the base station <NUM>. The UE <NUM> may identify a resource block set <NUM> that is a self-contained subset of the resource management block <NUM>. The resource block set <NUM> may be used to communicate control information for the sTTI <NUM> (and/or one or more other sTTIs). For example, the resource block set <NUM> may be used to communicate one or more downlink grants <NUM>, one or more uplink grants <NUM>, <NUM>, <NUM>, and/or the like. In some aspects, a portion of the resource block set <NUM> may be reallocated to the data region, shown as reallocated sPDSCH <NUM>, thereby reducing control overhead.

Other examples are possible and may differ from what was described in connection with <FIG>.

<FIG> illustrates an example of an uplink search space <NUM> for downlink control channel structures for low latency communications, in accordance with various aspects of the present disclosure. The sPDCCH uplink search space <NUM> may represent an uplink search space for an sPDCCH that may be or include one or more aspects of sPDCCH <NUM>, sPDCCH <NUM>, sPDCCH <NUM>, sPDCCH <NUM>, sPDCCH <NUM>, and sPDCCH <NUM>. The uplink search space <NUM> is shown for four aggregation levels, including a first aggregation level <NUM>, a second aggregation level <NUM>, a third aggregation level <NUM>, and a fourth aggregation level <NUM>. As described above, the uplink grants may be positioned at a boundary <NUM> (e.g., the end) of an sPDCCH control region. An uplink grant for UE A may be transmitted at first aggregation level <NUM>, an uplink grant for UE B may be transmitted at second aggregation level <NUM>, and an uplink grant for UE C may be transmitted at third aggregation level <NUM>.

As described above, an indication may identify the start of the uplink grant region, which may include uplink grant <NUM> for UE A, uplink grant <NUM> for UE B, and uplink grant <NUM> for UE C. The indication may be a rate matching information field in a downlink grant, for example downlink grant <NUM> for UE B transmitted at a second aggregation level <NUM>. As illustrated for uplink search space <NUM>, the indication may be three bits to identify one of eight different positions <NUM>. In this example, downlink grant <NUM> for UE B is transmitted at a second aggregation level <NUM> and includes an indication of "<NUM>" to indicate that the start of the uplink grant region is at "<NUM>" position of positions <NUM>. UE B, having received its downlink grant <NUM>, may then understand that the region <NUM> of the PDCCH control region between the end of the downlink grant <NUM> for UE B and the "<NUM>" position of positions <NUM>.

In other implementations, a greater or fewer number of positions for the start of the uplink grants may be indicated in the downlink grant. A greater number of positions <NUM> may be indicated by adding one or more bits, for example by increasing the size of the rate matching information field to four or more bits. Increasing the number of positions <NUM> may increase scheduling flexibility, but may also increase overhead the number of blind decode attempts for a UE receiver to search for uplink grants. Similarly, a smaller number of positions <NUM> may be indicated (e.g., four positions using two bits in the downlink grant), decreasing flexibility, but also decreasing overhead and the number of blind decode attempts for a UE receiver.

<FIG> illustrates an example resource structure <NUM> used for low latency communications, in accordance with various aspects of the present disclosure. Resource structure <NUM> provides an illustration of various groups of resources described herein. Resource structure <NUM> includes a subframe <NUM>, which may represent a TTI in some wireless communications systems (e.g., LTE systems). Subframe <NUM> may include multiple sTTIs <NUM>, which may represent a TTI in other wireless communications systems (e.g., low latency systems).

The sTTIs <NUM> may each include multiple symbols (e.g., two (<NUM>) or three (<NUM>)) symbols, and each sTTI <NUM> may be self-contained. That is, each sTTI <NUM> may include a control region that schedules the transmission of low latency data during the sTTI <NUM> (e.g., uplink or downlink low latency communications). Further, each sTTI <NUM> may be associated with an index that indicates a number of resource elements available for a transmission of downlink control information (DCI) in a control region of the sTTI <NUM>. For example, the third sTTI <NUM> in subframe <NUM> may be associated with an index of two (<NUM>), and a number of resource elements used for other signaling (e.g., CRS transmissions) in the third sTTI <NUM> may be determined based at least in part on the sTTI index.

The control region of an sTTI <NUM> may be referred to as an sPDCCH and/or a resource block set, and may be structured to support an efficient use of resources as described herein. As illustrated, a symbol <NUM> of an sTTI <NUM> includes multiple (i.e., two (<NUM>)) shortened control channel elements (sCCEs) <NUM> that span a portion of the system bandwidth. An sCCE <NUM> contains DCI that is used to provide control information for communications during the sTTI <NUM>. A base station <NUM> may transmit DCI during multiple sCCEs <NUM> (as shown), where the number of sCCEs <NUM> used for the transmission of DCI represents the aggregation level used by the base station for the transmission of DCI. In the example of <FIG>, a base station may utilize an aggregation level of two (<NUM>) for control transmissions to a UE <NUM> during an sTTI <NUM> (i.e., two sCCEs <NUM>). In other examples, a base station may utilize an aggregation level of one (<NUM>) (i.e., one sCCE <NUM>), four (<NUM>) (i.e., four sCCEs <NUM>), etc. for control transmissions to a UE <NUM> during an sTTI <NUM>.

Each sCCE <NUM> may include a fixed number of sREGs <NUM> (e.g., four (<NUM>)) or may include a variable number of sREGs <NUM> (not shown). Each sREG <NUM> may include one (<NUM>) resource block, which may include <NUM> resource elements <NUM> within a symbol <NUM>. As described above, in some cases, some resource elements <NUM> within an sREG <NUM> may be used for other signaling, such as cell-specific reference signal (CRS) signaling, demodulation reference signal (DMRS) signaling, channel state information-reference signal (CSI-RS) signaling, and/or the like.

A resource block set <NUM> may include one or more sCCEs <NUM>. In some aspects, the number of sCCEs <NUM> included in a resource block set <NUM> may be signaled to a UE <NUM> by a base station <NUM> using higher layer signaling (e.g., in an RRC connection configuration message). Additionally, or alternatively, such signaling may indicate the mapping of sCCEs <NUM> to sREGs <NUM>. In some aspects, the mapping may indicate a contiguous (e.g., localized) group of sREGs <NUM> included in an sCCE <NUM>. In some aspects, the mapping may indicate a non-contiguous (e.g., distributed) group of sREGs <NUM> included in an sCCE <NUM>. In some aspects, when the resource block set is configured with a DMRS based reference signal demodulation scheme, the mapping may be contiguous. In some aspects, when the resource block set is configured with a CRS based reference signal demodulation scheme, the mapping may be contiguous or non-contiguous.

In some aspects, the UE <NUM> may be configured with a single resource block set <NUM> that contains a UE-specific sTTI search space specific to the UE <NUM>. In some aspects, the UE <NUM> may be configured with multiple resource block sets <NUM> (e.g., two resource block sets <NUM>, more than two resource block sets <NUM>, etc.) that contain a UE-specific sTTI search space specific to the UE <NUM>.

A resource block set <NUM> may be self-contained within one resource management block. That is, a resource block set <NUM> may be embedded within a resource management block during an sTTI, and/or may include control information for the resource management block and the sTTI. In some aspects, a resource block set <NUM> may include control information for another resource management block other than the resource management block in which the resouce block set <NUM> is embedded, thereby reducing control overhead. Additionally, or alternatively, a resource block set <NUM> may include control information for another sTTI other than the sTTI during which the resouce block set <NUM> is transmitted or received, thereby further reducing control overhead.

<FIG> illustrate example resource structures <NUM> used for low latency communications, in accordance with various aspects of the present disclosure.

As shown in <FIG>, in some aspects, a resource management block may include a set of contiguous (e.g., localized) resource block groups (RBGs). As shown in <FIG>, in some aspects, a resource management block may include a set of non-contiguous (e.g., distributed) resource block groups. In some aspects, a base station <NUM> may indicate to a UE <NUM>, in a resource management block configuration, whether a resource management block includes contiguous or non-contiguous resource block groups. In the example resource structures <NUM>, a system bandwidth is <NUM>, a resource block group includes <NUM> resource blocks, and the resource block management configuration indicates three resource management blocks, shown as a first resource management block <NUM>, a second resource management block <NUM>, and a third resource management block <NUM>.

As shown in <FIG>, the first resource management block <NUM> may include a first set of RBGs <NUM>, the second resource management block <NUM> may include a second set of RBGs <NUM>, and the third resource management block <NUM> may include a third set of RBGs <NUM>. In some aspects, the number of RBGs included in a set of RBGs may be configurable based at least in part on a resource management block configuration. For example, the first set of RBGs <NUM> is shown as including <NUM> RBGs (e.g., <NUM> RBs), the second set of RBGs <NUM> is shown as including <NUM> RBGs (e.g., <NUM> RBs), and the third set of RBGs <NUM> is shown as including <NUM> RBGs (e.g., <NUM> RBs). In some aspects, a resource management block includes at least one resource block set.

As shown in <FIG>, a resource management block <NUM> may be referred to as a virtual resource management block when the resource management block <NUM> includes a set of non-contiguous RBGs. The resource management blocks shown in <FIG> may be downlink resource management blocks or uplink resource management blocks, and may be defined by higher layer signaling (e.g., during an RRC connection procedure). In some aspects, a resource management block may be cell-specific. In this way, the resource management block configuration may be shared across UEs <NUM> located in a cell, thereby reducing signaling and conserving network resources.

<FIG> illustrates an example resource structure <NUM> used for low latency communications, in accordance with various aspects of the present disclosure. As shown in <FIG>, a resource management block <NUM> may include at least one RB set <NUM>. The resource management block <NUM> shown in <FIG> corresponds to the virtual resource management block <NUM> shown in <FIG>. However, in some aspects, the resource management block <NUM> may correspond to one or more of the resource blocks shown in <FIG>.

In some aspects, the RB set <NUM> may be a subset of the resource management block <NUM>. In this way, the control region (e.g., sPDCCH) of resource management block <NUM> may be self-contained within resource management block <NUM>. For example, the RB set <NUM> may include a subset of the RBGs included in the resource management block <NUM>, shown as RBGs <NUM>. In some aspects, one or more RBGs of the resource management block <NUM> may not be included in the RB set <NUM>, shown as RBGs <NUM>. In some aspects, one or more RBGs <NUM> may be used for a data region of the resource management block <NUM> and/or may be used for another RB set of the resource management block <NUM>. In some aspects, ratematching may be performed to determine the sCCEs (and/or corresponding RBGs, REGs, etc.) used for control information in the RB set <NUM>, and sCCEs (and/or corresponding RBGs, REGs, etc.) not used for control information may be reallocated to a data region (e.g., an sPDSCH), as described elsewhere herein.

In some aspects, the RB set is cell-specific. Additionally, or alternatively, a number of symbols used for the RB set may be cell-specific. In this way, the resource management block configuration (e.g., a configuration of an RB set) may be shared across UEs <NUM> located in a cell, thereby reducing signaling and conserving network resources.

In some aspects, the RB set is configured with a DMRS based reference signal demodulation scheme. In some aspects, the RB set is configured with a CRS based reference signal demodulation scheme. In some aspects, RB sets configured with different types of reference signal demodulation schemes may be different. For example, a first RB set that is configured with a first reference signal demodulation scheme may at least partially overlap (e.g., may partially overlap or completely overlap) a second RB set that is configured with a second reference signal demodulation scheme. In some aspects, a first RB set that is configured with a first reference signal demodulation scheme may not overlap with a second RB set that is configured with a second reference signal demodulation scheme. In some aspects, an RB set configured with a DMRS based reference signal demodulation scheme may be a contiguous (e.g., localized) set of REGs. In some aspects, an RB set configured with a CRS based reference signal demodulation scheme may be a non-contiguous (e.g., distributed) set of REGs. In some aspects, all CRS based sPDCCHs in a resource management block may have an identical RB set. In some aspects, all DMRS based sPDCCHs in a resource management block may have an identical RB set.

In some aspects, CRS communications may be disabled in subframes configured for multicast broadcast single frequency communication, and demodulation of a control region and a data region in these subframes may be based at least in part on a DMRS based reference signal demodulation scheme. In this way, control overhead may be reduced.

<FIG> illustrates an example resource structure <NUM> used for low latency communications, in accordance with various aspects of the present disclosure. As shown in <FIG>, in some aspects, an sTTI <NUM> may include three symbols, shown as a first symbol <NUM>, a second symbol <NUM>, and a third symbol <NUM>. In this case, information received in the third symbol <NUM> may be demodulated according to a demodulation rule, which may be indicated in a resource management block configuration. As further shown, an RB set <NUM> may include a first portion <NUM> that includes downlink control information <NUM>, a second portion <NUM> that includes uplink control information <NUM>, and a reallocated sPDSCH portion <NUM>, as described above in connection with RB set <NUM> of <FIG>. In example resource structure <NUM>, each of the first portion <NUM>, the second portion <NUM>, and the reallocated sPDSCH portion <NUM> occupy the three symbols of the sTTI <NUM>.

In the example of <FIG>, a control region of the RB set <NUM> may be configured with a DMRS based reference signal demodulation scheme or a CRS based reference signal demodulation scheme, and a data region of the sTTI <NUM> may be configured with a DMRS based reference signal demodulation scheme. In this case, one or more DMRS signals from the first two symbols (e.g., the first symbol <NUM> and/or the second symbol <NUM>) may be used to demodulate data in the third symbol <NUM> and/or the data region of the sTTI <NUM> (e.g., as indicated by a demodulation rule). By frequency division multiplexing the first portion <NUM>, the second portion <NUM>, and the reallocated sPDSCH <NUM>, complexity may be reduced.

<FIG> illustrates an example resource structure <NUM> used for low latency communications, in accordance with various aspects of the present disclosure. As shown in <FIG>, in some aspects, an sTTI <NUM> may include three symbols, shown as a first symbol <NUM>, a second symbol <NUM>, and a third symbol <NUM>. In this case, information received in the third symbol <NUM> may be demodulated according to a demodulation rule, which may be indicated in a resource management block configuration. As further shown, an RB set <NUM> may include a first portion <NUM> that includes downlink control information <NUM> and a reallocated sPDSCH portion <NUM> (e.g., in the first symbol <NUM>, the second symbol <NUM>, and the third symbol <NUM>), a second portion <NUM> that includes uplink control information <NUM> and a reallocated sPDSCH portion <NUM> (e.g., in the third symbol <NUM>). In example resource structure <NUM>, each of the first portion <NUM> and the second portion <NUM> occupy the three symbols of the sTTI <NUM>.

In the example of <FIG>, a control region of the RB set <NUM> may be configured with a DMRS based reference signal demodulation scheme, and a data region of the sTTI <NUM> may be configured with a DMRS based reference signal demodulation scheme. In this case, one or more CRS signals from the first two symbols (e.g., the first symbol <NUM> and/or the second symbol <NUM>) may be used to demodulate the third symbol <NUM> and/or a data region of the sTTI <NUM> (e.g., as indicated by a demodulation rule). Alternatively, a DMRS signal from a previous sTTI <NUM> may be used to demodulate data in the third symbol <NUM> and/or the data region (e.g., using open-loop precoding).

<FIG> illustrates an example resource structure <NUM> used for low latency communications, in accordance with various aspects of the present disclosure. As shown in <FIG>, in some aspects, an sTTI <NUM> may include three symbols, shown as a first symbol <NUM>, a second symbol <NUM>, and a third symbol <NUM>. In this case, information received in the third symbol <NUM> may be demodulated according to a demodulation rule, which may be indicated in a resource management block configuration. As further shown, an RB <NUM> within an RB set may be allocated in the sTTI <NUM>.

In the example of <FIG>, a control region of the RB set may be configured with a CRS based reference signal demodulation scheme, and a data region of the sTTI <NUM> may be configured with a DMRS based reference signal demodulation scheme. In this case, a UE may use blind decoding to identify a DRMS signal to be used to demodulate the third symbol <NUM> and/or data in a data region of the sTTI.

<FIG> shows a block diagram <NUM> of a wireless device <NUM> that supports downlink control channel structures for low latency communications, in accordance with various aspects of the present disclosure. Wireless device <NUM> may be an example of aspects of a user equipment (UE) <NUM> as described with reference to <FIG>. Wireless device <NUM> may include receiver <NUM>, UE downlink (DL) control manager <NUM>, and transmitter <NUM>. Wireless device <NUM> may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

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 downlink control channel structure for low latency communications, etc.). Information may be passed on to other components of the wireless device <NUM>. The receiver <NUM> may be an example of aspects of the transceiver <NUM> described with reference to <FIG>.

UE DL control manager <NUM> may be an example of aspects of the UE DL control manager <NUM> described with reference to <FIG>.

UE DL control manager <NUM> may identify a resource management block based at least in part on a resource management block configuration indicated by a base station, wherein the resource management block spans a portion of a system bandwidth in an sTTI. UE DL control manager <NUM> may identify a resource block set that is a self-contained subset of the resource management block, wherein the resource block set includes a control region with control information for the UE for the sTTI. UE DL control manager <NUM> may use the control information to locate content, intended for the wireless device <NUM>, at least partially within a data region of the sTTI.

<FIG> shows a block diagram <NUM> of a wireless device <NUM> that supports downlink control channel structures for low latency communications, 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> as described with reference to <FIG> and <FIG>. Wireless device <NUM> may include receiver <NUM>, UE DL control manager <NUM>, and transmitter <NUM>. Wireless device <NUM> may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

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 downlink control channel structure for low latency communications, etc.). 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>.

UE DL control manager <NUM> may be an example of aspects of the UE DL control manager <NUM> described with reference to <FIG>. UE DL control manager <NUM> may also include resource management block (RMB) identification component <NUM>, RB set identification componenet <NUM>, and control information usage component <NUM>. RMB identification component <NUM> may identify a resource management block based at least in part on a resource management block configuration indicated by a base station, wherein the resource management block spans a portion of a system bandwidth in an sTTI. RB set identification componenet <NUM> may identify a resource block set that is a self-contained subset of the resource management block, wherein the resource block set includes a control region with control information for the UE for the sTTI. Control information usage component <NUM> may use the control information to locate content, intended for the wireless device <NUM>, at least partially within a data region of the sTTI.

<FIG> shows a diagram of a system <NUM> including a device <NUM> that supports downlink control channel structures for low latency communications, in accordance with various aspects of the present disclosure. Device <NUM> may be an example of or include the components of wireless device <NUM>, wireless device <NUM>, or a UE <NUM> as described above, e.g., with reference to <FIG>, <FIG> and <FIG>. Device <NUM> may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including UE DL control manager <NUM>, processor <NUM>, memory <NUM>, software <NUM>, transceiver <NUM>, antenna <NUM>, and I/O controller <NUM>. These components may be in electronic communication via one or more busses (e.g., bus <NUM>). Device <NUM> may communicate wirelessly with one or more base stations <NUM>.

Processor <NUM> 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), an fieldprogrammable 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, processor <NUM> may be configured to operate a memory array using a memory controller. In other cases, a memory controller may be integrated into processor <NUM>. Processor <NUM> may be configured to execute computer-readable instructions stored in a memory to perform various functions (e.g., functions or tasks supporting downlink control channel structure for low latency communications).

Software <NUM> may include code to implement aspects of the present disclosure, including code to support downlink control channel structure for low latency communications. Software <NUM> may be stored in a non-transitory computer-readable medium such as system memory or other memory. 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.

<FIG> shows a block diagram <NUM> of a wireless device <NUM> that supports downlink control channel structures for low latency communications, in accordance with various aspects of the present disclosure. Wireless device <NUM> may be an example of aspects of a base station <NUM> as described with reference to <FIG>. Wireless device <NUM> may include receiver <NUM>, base station DL control manager <NUM>, and transmitter <NUM>. Wireless device <NUM> may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

Base station DL control manager <NUM> may be an example of aspects of the base station DL control manager <NUM> described with reference to <FIG>.

Base station DL control manager <NUM> may indicate a resource management block configuration that identifies a plurality of resource management blocks that span at least a portion of system bandwidth and are allocated in an sTTI.

In some aspects, transmitter <NUM> may transmit control information for the sTTI in a resource block set that is a self-contained subset of a resource management block of the plurality of resource management blocks.

<FIG> shows a diagram of a system <NUM> including a device <NUM> that supports downlink control channel structures for low latency communications, in accordance with various aspects of the present disclosure. Device <NUM> may be an example of or include the components of base station <NUM> as described above, e.g., with reference to <FIG>. Device <NUM> may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including base station DL control manager <NUM>, processor <NUM>, memory <NUM>, software <NUM>, transceiver <NUM>, antenna <NUM>, network communications manager <NUM>, and base station communications manager <NUM>. These components may be in electronic communication via one or more busses (e.g., bus <NUM>). Device <NUM> may communicate wirelessly with one or more UEs <NUM>.

Processor <NUM> 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, processor <NUM> may be configured to operate a memory array using a memory controller. In other cases, a memory controller may be integrated into processor <NUM>. Processor <NUM> may be configured to execute computer-readable instructions stored in a memory to perform various functions (e.g., functions or tasks supporting downlink control channel structure for low latency communications).

Base station communications manager <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 manager <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 manager <NUM> may provide an X2 interface within an Long Term Evolution (LTE)/LTE-A wireless communication network technology to provide communication between base stations <NUM>.

<FIG> shows a flowchart illustrating a method <NUM> for downlink control channel structures for low latency communications, in accordance with various aspects of the present disclosure. The operations of method <NUM> may be implemented by a UE <NUM> or its components as described herein. For example, the operations of method <NUM> may be performed by a UE DL control manager as described with reference to <FIG>. In some examples, a UE <NUM> may execute a set of codes to control the functional elements of the UE <NUM> 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 identify a resource management block based at least in part on a resource management block configuration indicated by a base station, wherein the resource management block spans a portion of a system bandwidth in an sTTI. The operations of block <NUM> may be performed according to the methods described with reference to <FIG>. In certain examples, aspects of the operations of block <NUM> may be performed by one or more components as described with reference to <FIG>. In some aspects, the resource management block includes a set of contiguous resource block groups. In some aspects, the resource management block includes a set of non-contiguous resource block groups.

At block <NUM>, the UE <NUM> may identify a resource block set that is a self-contained subset of the resource management block, wherein the resource block set includes a control region with control information for the UE for the sTTI. The operations of block <NUM> may be performed according to the methods described with reference to <FIG>. In certain examples, aspects of the operations of block <NUM> may be performed by one or more components as described with reference to <FIG>. In some aspects, the resource block set is a set of contiguous resource element groups. In some aspects, the resource block set is a set of non-contiguous resource element groups.

In some aspects, the resource block set is cell-specific and a number of symbols used for the resource block set is cell-specific. In some aspects, the resource block set is configured with a demodulation reference signal (DMRS) based reference signal demodulation scheme or a cell-specific reference signal (CRS) based reference signal demodulation scheme. In some aspects, the resource block set at least partially overlaps with another resource block set that uses a different reference signal demodulation scheme than the resource block set. In some aspects, the resource block set does not overlap with another resource block set that uses a different reference signal demodulation scheme than the resource block set.

At block <NUM>, the UE <NUM> may use the control information to locate content, intended for the UE <NUM>, at least partially within a data region of the sTTI. The operations of block <NUM> may be performed according to the methods described with reference to <FIG>. In certain examples, aspects of the operations of block <NUM> may be performed by one or more components as described with reference to <FIG>.

Process <NUM> may include additional aspects, such as any single aspect or any combination of aspects described below and/or in connection with one or more other processes described herein.

In some aspects, cell-specific reference signal (CRS) communications are disabled in subframes configured for multicast broadcast single frequency communication, and demodulation of a control region and a data region in these subframes is based at least in part on a demodulation reference signal (DMRS) based reference signal demodulation scheme.

In some aspects, the control region of the resource block set is configured with a demodulation reference signal (DMRS) based reference signal demodulation scheme or a cell-specific reference signal (CRS) based reference signal demodulation scheme, the sTTI includes three symbols and the data region is configured with a DMRS based reference signal demodulation scheme, and one or more DMRS signals from the first two symbols are used to demodulate data in the data region.

In some aspects, the control region of the resource block set and the data region of the sTTI are configured with a demodulation reference signal (DMRS) based reference signal demodulation scheme, the sTTI includes three symbols, and one or more cell-specific reference signals from the first two symbols are used to demodulate data in the data region.

In some aspects, the control region of the resource block set and the data region of the sTTI are configured with a demodulation reference signal (DMRS) based reference signal demodulation scheme, the sTTI includes three symbols, and a DMRS signal in a previous sTTI is used to demodulate data in the data region using open-loop precoding.

In some aspects, the control region of the resource block set is configured with a cell-specific reference signal (CRS) based reference signal demodulation scheme, the sTTI includes three symbols and the data region is configured with a demodulation reference signal (DMRS) based reference signal demodulation scheme, and blind decoding is used to identify a DMRS signal to be used to demodulate data in the data region.

Although <FIG> shows example blocks of method <NUM>, in some implementations, method <NUM> may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in <FIG>. Additionally, or alternatively, two or more of the blocks of method <NUM> may be performed in parallel.

<FIG> shows a flowchart illustrating a method <NUM> for downlink control channel structures for low latency communications, in accordance with various aspects of the present disclosure. The operations of method <NUM> may be implemented by a base station <NUM> or its components as described herein. For example, the operations of method <NUM> may be performed by a base station DL control manager as described with reference to <FIG> and <FIG>. In some examples, a base station <NUM> may execute a set of codes to control the functional elements of the base station <NUM> 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 indicate a resource management block configuration that identifies a plurality of resource management blocks that span at least a portion of system bandwidth and are allocated in an sTTI. The operations of block <NUM> may be performed according to the methods described with reference to <FIG>. In certain examples, aspects of the operations of block <NUM> may be performed by one or more components as described with reference to <FIG> and <FIG>.

At block <NUM>, the base station <NUM> may transmit control information for the sTTI in a resource block set that is a self-contained subset of a resource management block of the plurality of resource management blocks. The operations of block <NUM> may be performed according to the methods described with reference to <FIG>. In certain examples, aspects of the operations of block <NUM> may be performed by one or more components as described with reference to <FIG> and <FIG>.

Process <NUM> may include additional aspects, such as any single aspect or any combination of aspects described in connection with one or more other processes described herein.

<FIG> shows a flowchart illustrating a method <NUM> for downlink control channel structures for low latency communications, in accordance with various aspects of the present disclosure. The operations of method <NUM> may be implemented by a UE <NUM> or its components as described herein. For example, the operations of method <NUM> may be performed by a UE DL control manager as described with reference to <FIG>. In some examples, a UE <NUM> may execute a set of codes to control the functional elements of the UE <NUM> to perform the functions described below. Additionally or alternatively, the UE <NUM> may perform the functions described below using special-purpose hardware.

At block <NUM>, the UE <NUM> identifies a resource block set that includes a data region and a control region, wherein the resource block set spans a portion of a system bandwidth in a shortened transmission time interval (sTTI), wherein the sTTI includes three symbols, wherein the control region occupies the three symbols and includes control information for the UE for the sTTI, and wherein the control region and the data region are frequency division multiplexed. The operations of block <NUM> may be performed according to the methods described with reference to <FIG>. In certain examples, aspects of the operations of block <NUM> may be performed by one or more components as described with reference to <FIG>.

At block <NUM>, the UE <NUM> obtains content in the sTTI based at least in part on the control information. The operations of block <NUM> may be performed according to the methods described with reference to <FIG>. In certain examples, aspects of the operations of block <NUM> may be performed by one or more components as described with reference to <FIG>.

In some aspects, the data region occupies the three symbols. In some aspects, the control region includes a first portion that includes downlink control information and a second portion that includes uplink control information. In some aspects, the first portion and the second portion are frequency division multiplexed. In some aspects, the data region is located between the first portion and the second portion within the resource block set. In some aspects, the data region is a reallocated data region.

In some aspects, one or more resources to be used for the data region are signaled in the control region. In some aspects, the control region is configured with a demodulation reference signal (DMRS) based reference signal demodulation scheme or a cell-specific reference signal (CRS) based reference signal demodulation scheme. In some aspects, the data region is configured with a demodulation reference signal (DMRS) based reference signal demodulation scheme. In some aspects, the three symbols include a first symbol that occurs before a second symbol that occurs before a third symbol, and wherein one or more demodulation reference signal (DMRS) signals from at least one of the first symbol or the second symbol are used to demodulate information in the third symbol.

The terms "system" and "network" are often used interchangeably. A code division multiple access (CDMA) system may implement a radio technology such as CDMA2000, Universal Terrestrial Radio Access (UTRA), etc. CDMA2000 covers IS-<NUM>, IS-<NUM>, and IS-<NUM> standards. A time division multiple access (TDMA) system may implement a radio technology such as Global System for Mobile Communications (GSM).

An orthogonal frequency division multiple access (OFDMA) system may implement a radio technology such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), Institute of Electrical and Electronics Engineers (IEEE) <NUM> (Wi-Fi), IEEE <NUM> (WiMAX), IEEE <NUM>, Flash-OFDM, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunications system (UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are new releases of Universal Mobile Telecommunications System (UMTS) that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and Global System for Mobile communications (GSM) are described in documents from the organization named "3rd Generation Partnership Project" (3GPP). While aspects an LTE system may be described for purposes of example, and LTE terminology may be used in much of the description, the techniques described herein are applicable beyond LTE applications.

In LTE/LTE-A networks, including such 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 evolved node B (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" may be used to describe a base station, a carrier or component carrier 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, 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.

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.

By way of example, and not limitation, non-transitory computer-readable media may 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. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave are included in the definition of medium.

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 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.

Claim 1:
A method for downlink control channel structure of wireless communication performed by a user equipment, UE, comprising:
identifying (<NUM>) a resource block set that includes a data region and a control region, wherein the resource block set spans a portion of a system bandwidth in a shortened transmission time interval, sTTI, wherein the sTTI includes three symbols, wherein the control region occupies the three symbols and includes control information for the UE for the sTTI, and wherein the control region and the data region are frequency division multiplexed, and wherein the control region includes a first portion that includes downlink control information and a second portion that includes uplink control information, and wherein the data region is located between the first portion and the second portion within the resource block set; and
obtaining (<NUM>) content in the sTTI based at least in part on the control information.