Patent Description:
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 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 in some LTE or NR deployments may transmit to one or more UEs using a transmission time interval (TTI) that is reduced in length relative to legacy LTE TTIs. Such a TTI may be referred to as a shortened TTI (sTTI) and users communicating using sTTIs may be referred to as low latency users. A sTTI may be a subset of one or more subframes that correspond to legacy TTI subframes. The use of sTTIs may help reduce latency for wireless communications and may be used in some cases when low latency communications are desirable. A base station may allocate transmission resources for sTTIs to a UE that may include time and/or frequency resources. Efficient allocation of such resources for data, requests for resource allocations, and communications related to allocations may help to further reduce latency for users and may help to increase the efficiency of a wireless communications system. <CIT> is directed to configuring a random access channel in a short transmission time interval or contention based uplink transmission and contention based scheduling request (CB-SR) transmission in a wireless communication system. Thereby, the CB-SR transmission enables more frequent transmission of SR by configuring SR with shorter SR period and therefore, the UE can inform the eNB of need for UL grant as soon as possible if SR is successfully transmitted. <NPL>) is directed to beam failure recovery mechanism and teaches that if beam failure recovery procedure is triggered when the quality X (<Y) out of Y beam pair links falls below certain threshold, then the UE may be able to transmit a beam failure recovery request on the configured resource, which can be shared with resource for other usage, e.g., SR. The gNB is then able to receive the beam failure recovery request and identify the UE by the resource on which it is received. <NPL>) considers RACH preamble design for NR and teaches that a possible use case of the short PRACH sequences is the contention based synchronized PRACH for the RRC Connected UEs to send the scheduling request. Thereby, sets of orthogonal time slots for UE selection, equivalently increasing the PRACH capacity for SR transmission are introduced. Further, it is observed that if the RACH procedure is to be supported for scheduling request purpose in NR, the short RACH sequence with CP can be considered.

The described techniques relate to improved methods, systems, devices, or apparatuses that support scheduling request (SR) techniques in wireless transmissions. Generally, the described techniques provide for SR resources that may be used by a user equipment (UE) to request uplink resources. In some cases, a base station may allocate SR resources within random access channel resources, and a UE may use the SR resources to transmit a SR. In some examples, the random access resources may be allocated in a first duration transmission time interval (TTI) that has a duration that is shorter than a second duration TTI (e.g., a <NUM> legacy LTE TTI duration). In some instances, the SR resources may be a subset of random access preambles associated with the random access resources. In some aspects, the first duration TTI may correspond to a two-symbol TTI or a three-symbol TTI. In some cases, the three-symbol TTI may include a reference signal transmission in the last symbol of the TTI, and in such cases the random access resources of the three-symbol TTI may be converted to random access resources for a two-symbol TTI.

Improved methods, systems, devices, or apparatuses of various examples may be used to support scheduling request (SR) transmissions with shortened transmission time intervals (TTIs) in low latency wireless communications Resources allocated for low latency communications, such as ultra-reliable low latency communications (URLLC), may be used for uplink and downlink communication using shortened TTIs (sTTIs) that have a reduced length relative to TTIs of communications that may be relatively latency insensitive, such as mobile broadband (MBB) transmissions that may use a <NUM> TTI duration. Communications using sTTIs may use, in some cases, a TTI duration that corresponds to one slot of a wireless subframe, or a TTI duration that corresponds to two or three orthogonal frequency division multiplexing (OFDM) symbols, for example. In some examples, sTTIs may be configured to have boundaries within or aligned with boundaries of a slot of a <NUM> TTI, which may be referred to as slot-aligned TTIs. In some examples, the TTIs may span two or three OFDM symbols, and each slot may have two two-symbol TTIs and one three-symbol TTI. In such a manner, all seven symbols of a slot using a normal cyclic prefix (CP) may be utilized and system resources may be more efficiently utilized.

Various techniques as disclosed herein may provide configurations for SR transmissions in sTTIs, such as TTIs spanning two or three OFDM symbols. In some cases, a base station may allocate random access resources in certain sTTIs for random access request transmissions from a UE to the base station. The base station may allocate a portion of such random access resources for SR transmissions, the these SR resources may be used by a UE to request uplink resources. In some examples, the SR resources may be a subset of random access preambles associated with the random access resources. In some instances, a three-symbol TTI may include a reference signal transmission in the last symbol of the TTI, and in such cases the random access resources of the three-symbol TTI may be converted to random access resources for a two-symbol TTI.

Such low latency communications may be used in systems, for example, that may support multiple different services for data communications that may be selected depending upon the nature of the communications. For example, communications that require low latency and high reliability, sometimes referred to as mission critical (MiCr) communications, may be served through a lower-latency service (e.g., a URLLC service) that uses sTTIs. Correspondingly, communications that are more delay-tolerant may be served through a service that provides relatively higher throughput with somewhat higher latency, such as a mobile broadband service (e.g., an enhanced MBB (eMBB) service) that uses <NUM> TTIs. In other examples, communications may be with UEs that are incorporated into other devices (e.g., meters, vehicles, appliances, machinery), and a machine-type communication (MTC) service (e.g., massive MTC (mMTC)) may be used for such communications. In some cases, different services (e.g., eMBB, URLLC, mMTC) may have different TTIs, different sub-carrier (or tone) spacing and different CPs.

Aspects of the disclosure are initially described in the context of a wireless communications system. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to SR techniques in wireless transmissions.

<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 Long Term Evolution (LTE), LTE-Advanced (LTE-A) network, or a New Radio (NR) network. In some cases, wireless communications system <NUM> may support enhanced broadband communications, ultra-reliable (i.e., MiCr) communications, low latency communications, and communications with low-cost and low-complexity devices. UEs <NUM> and base stations <NUM> may communicate using low latency communications in which SR resources may be allocated within random access resources.

Each base station <NUM> may provide communication coverage for a respective geographic coverage area <NUM>. Control information and data may be multiplexed on an uplink channel or downlink according to various techniques. Control information and data may be multiplexed on a downlink channel, for example, using time division multiplexing (TDM) techniques, frequency division multiplexing (FDM) techniques, or hybrid TDM-FDM techniques. In some examples, the control information transmitted during a TTI of a downlink channel may be distributed between different control regions in a cascaded manner (e.g., between a common control region and one or more UE-specific control regions).

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 MTC device, an appliance, an automobile, or the like.

In some examples, groups of UEs <NUM> communicating via D2D communications may utilize a one-to-many (<NUM>:M) system in which each UE <NUM> transmits to every other UE <NUM> in the group. In some instances, a base station <NUM> facilitates the scheduling of resources for D2D communications.

For example, base stations <NUM> may interface with the core network <NUM> through backhaul links <NUM> (e.g., S1). Base stations <NUM> may communicate with one another over backhaul links <NUM> (e.g., X2) either directly or indirectly (e.g., through core network <NUM>).

The core network <NUM> may provide user authentication, access authorization, tracking, IP connectivity, and other access, routing, or mobility functions. At least some of the network devices, such as base station <NUM> may include subcomponents such as an access network entity, which may be an example of an access node controller (ANC). Each access network entity may communicate with a number of UEs <NUM> through a number of other access network transmission entities, each of which may be an example of a smart radio head, or a transmission/reception point (TRP). In some configurations, various functions of each access network entity or base station <NUM> may be distributed across various network devices (e.g., radio heads and ANCs) or consolidated into a single network device (e.g., a base station <NUM>).

Wireless communications system <NUM> may operate in an ultra-high frequency (UHF) frequency region using frequency bands from <NUM> to <NUM> (<NUM>), although some networks (e.g., a wireless local area network (WLAN)) may use frequencies as high as <NUM>. This region may also be known as the decimeter band, since the wavelengths range from approximately one decimeter to one meter in length. UHF waves may propagate mainly by line of sight, and may be blocked by buildings and environmental features. However, the waves may penetrate walls sufficiently to provide service to UEs <NUM> located indoors. Transmission of UHF waves is characterized by smaller antennas and shorter range (e.g., less than <NUM>) compared to transmission using the smaller frequencies (and longer waves) of the high frequency (HF) or very high frequency (VHF) portion of the spectrum. In some cases, wireless communications system <NUM> may also utilize extremely high frequency (EHF) portions of the spectrum (e.g., from <NUM> to <NUM>). This region may also be known as the millimeter band, since the wavelengths range from approximately one millimeter to one centimeter in length. Thus, EHF antennas may be even smaller and more closely spaced than UHF antennas. In some examples, this may facilitate use of antenna arrays within a UE <NUM> (e.g., for directional beamforming). However, EHF transmissions may be subject to even greater atmospheric attenuation and shorter range than UHF transmissions.

A Radio Link Control (RLC) layer may in some examples perform packet segmentation and reassembly to communicate over logical channels. The MAC layer may also use Hybrid Automatic Repeat Request (HARQ) to provide retransmission at the MAC layer to improve link efficiency. 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 a network device, network device, or core network <NUM> supporting radio bearers for user plane data.

Time intervals in LTE or NR may be expressed in multiples of a basic time unit (which may be a sampling period of Ts = <NUM>/<NUM>,<NUM>,<NUM> seconds). Time resources may be organized according to radio frames of length of <NUM> (Tf = 307200Ts), 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 CP prepended to each symbol). Excluding the CP, 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, such as discussed herein, a TTI may be shorter than a subframe or may be dynamically selected (e.g., in sTTI bursts or in selected component carriers using sTTIs).

A resource element may consist of one symbol period and one subcarrier (e.g., a <NUM> frequency range). A resource block (RB) may contain <NUM> consecutive subcarriers in the frequency domain and, for a normal CP 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 RBs that a UE <NUM> receives and the higher the modulation scheme, the higher the data rate may be.

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 be configured with multiple downlink CCs and one or more uplink CCs for CA. CA may be used with both FDD and TDD component carriers.

In some cases, wireless communications system <NUM> may utilize enhanced CCs (eCCs). An eCC may be characterized by one or more features including: wider bandwidth, shorter symbol duration, shorter TTIs, and modified control channel configuration. In some examples, an eCC may be associated with a CA configuration or a dual connectivity configuration (e.g., when multiple serving cells have a suboptimal or non-ideal backhaul link). An eCC may also be configured for use in unlicensed spectrum or shared spectrum (where more than one operator is allowed to use the spectrum). An eCC characterized by wide bandwidth may include one or more segments that may be utilized by UEs <NUM> that are not capable of monitoring the whole bandwidth or prefer to use a limited bandwidth (e.g., to conserve power).

A shorter symbol duration is associated with increased subcarrier spacing. A device, such as a UE <NUM> or base station <NUM>, utilizing eCCs may transmit wideband signals (e.g., <NUM>, <NUM>, <NUM>, or <NUM>) at reduced symbol durations (e.g., <NUM> microseconds). A TTI in eCC may consist of one or multiple symbols. In some examples, the TTI duration (that is, the number of symbols in a TTI) may be variable.

For example, wireless system <NUM> may employ LTE License Assisted Access (LTE-LAA) or LTE Unlicensed (LTE U) radio access technology or NR technology in an unlicensed band such as the <NUM> Industrial, Scientific, and Medical (ISM) band. When operating in unlicensed radio frequency spectrum bands, wireless devices such as base stations <NUM> and UEs <NUM> may employ listen-before-talk (LBT) procedures to ensure the channel is clear before transmitting data. In some examples, operations in unlicensed bands may be based on a CA configuration in conjunction with CCs operating in a licensed band. Operations in unlicensed spectrum may include downlink transmissions, uplink transmissions, or both. Duplexing in unlicensed spectrum may be based on frequency division duplexing (FDD), time division duplexing (TDD) or a combination of both.

In some cases, a base station <NUM> may configure certain resources for SR transmissions in sTTIs. In some examples, the base station <NUM> may allocate random access resources in certain sTTIs for random access request transmissions from a UE <NUM> to the base station <NUM>. The base station <NUM> may allocate a portion of such random access resources for SR transmissions, the these SR resources may be used by the UE <NUM> to request uplink resources. In some instances, the SR resources may be a subset of random access preambles associated with the random access resources. In some aspects, a three-symbol TTI may include a reference signal transmission in the last symbol of the TTI, and in such cases the random access resources of the three-symbol TTI may be converted to random access resources for a two-symbol TTI.

<FIG> illustrates an example of a wireless communications system <NUM> that supports SR techniques in wireless transmissions in accordance with various aspects of the present disclosure. Wireless communications system <NUM> includes base station <NUM>-a and UE <NUM>-a, which may be examples of aspects of a base station <NUM> and a UE <NUM> as described above with reference to <FIG>. In the example of <FIG>, the wireless communications system <NUM> may operate according to a radio access technology (RAT) such as a LTE, a <NUM> or NR RAT, although techniques described herein may be applied to any RAT and to systems that may concurrently use two or more different RATs.

Base station <NUM>-a may communicate with UE <NUM>-a over an uplink carrier <NUM> and a downlink carrier <NUM>. In some examples, base station <NUM>-a may allocate resources for communication with UEs <NUM> over uplink carrier <NUM> and downlink carrier <NUM>. For example, base station <NUM>-a may allocate uplink subframes <NUM> in uplink carrier <NUM> for uplink transmissions from UE <NUM>-a, and one or more uplink subframes <NUM> may correspond to a legacy LTE TTI of <NUM> or a sTTI of two or three OFDM symbols. In this example, uplink subframes <NUM> may include a first uplink subframe <NUM>-a, a second uplink subframe <NUM>-b, and a third uplink subframe <NUM>-c. Each of the uplink subframes <NUM> may include two slots, in which each slot may have seven OFDM symbols for a normal CP. In this example, a first slot (slot <NUM>) <NUM> and a second slot (slot <NUM>) <NUM> may be included in the first subframe <NUM>-a.

As indicated above, in low latency communications, different TTI lengths may be used for transmissions over uplink carrier <NUM>, downlink carrier <NUM>, or both. For example, two or three symbol TTI and <NUM>-slot TTI durations may be supported for physical random access channel (PRACH) transmissions (or shortened PRACH (sPRACH) transmissions). Thus, within first slot <NUM> or second slot <NUM>, there may be multiple TTIs, such as a first TTI (TTI-<NUM>) <NUM>, a second TTI (TTI-<NUM>) <NUM>, and a third TTI (TTI-<NUM>) <NUM>, that may each have a two or three OFDM symbol duration. Such TTI durations may also apply to downlink subframes <NUM> transmitted on downlink carrier <NUM>. In some examples, different length TTIs may be used on the uplink carrier <NUM> and the downlink carrier <NUM>, resulting in asymmetric TTI lengths for uplink and downlink transmissions.

When two or three symbol TTIs are used, in some cases it may be desirable to have a fixed TTI structure in which TTI boundaries lie within slot boundaries or are aligned with slot boundaries, such as the boundaries of the first slot <NUM> or second slot <NUM>, which may be referred to as slot-aligned TTIs. As discussed above, when using a normal CP, seven symbols are included in each slot <NUM> - <NUM>, and thus each slot may include three TTIs for slot-aligned TTIs. In some examples, one of the TTIs may be configured as a three-symbol TTI, so as to efficiently utilize each symbol of each slot. In such cases, different patterns can be considered, such as having the three-symbol TTI located at the end of a slot <NUM>-<NUM>, or at the beginning of a slot <NUM>-<NUM>. When using two-symbol TTIs or a combination of two-symbol and three-symbol TTIs, such TTIs may be referred to as <NUM>-symbol TTIs. When using TTIs having a duration correspond to a subframe, such TTIs may be referred to as <NUM> TTIs or legacy TTIs.

Various aspects of the present disclosure provide SR techniques when using sTTIs. In some cases, the base station <NUM>-a may configure PRACH resources within certain TTIs. Within the PRACH resources, the base station <NUM>-a may further configure a subset of resources for SR transmissions. In some cases, the base station <NUM>-a also may configure SR to transmitted in physical uplink control channel (PUCCH) transmissions (or shortened PUCCH (sPUCCH) transmissions) along with feedback information (e.g., HARQ feedback) that may be transmitted in the PUCCH transmissions. For example, additional cyclic shifts may be used with a within a <NUM> RB/two-symbol transmission to convey SR. In some examples, certain PRACH preambles may be reserved by the base station <NUM>-a for SR transmissions, which may be communicated to the UE <NUM>-a and then used by the UE <NUM>-a to transmit SRs. In some instances, SR using sTTIs may use existing LTE legacy PRACH preamble format <NUM>, and messages <NUM>-<NUM> of the PRACH procedure may be transmitted on the sTTI timelines, which may reduce overall latency for low latency communications. In some aspects, the PRACH resources may be allocated relatively frequently in order to help reduce startup latency for random access requests. Further, depending upon the level of loading at the base station <NUM>-a, all PRACH resources may not be required, and SR resources in some cases may be allocated based on such loading. In such cases, if the UE <NUM>-a does not have a feedback transmission (e.g., acknowledgement (ACK) feedback or negative ACK (NACK) feedback), it may instead send SR on assigned resource within the PRACH resource. In some examples, the allocated SR resources may be a portion of preamble signatures that may be allocated to connected mode UEs for SR, with remaining signatures used for fast random access functionality. In some instances, in order to avoid split band transmission on PUCCH and PRACH, if the UE <NUM>-a has a SR and ACK/NACK that are both to be transmitted, it may transmit only in PUCCH resources. Such transmissions may help to provide a good peak to average power ratio (PAPR) and avoid radio frequency (RF) intermodulation performance issues due to split band transmissions.

When transmitting a SR on PRACH resources, in some cases a UE <NUM>-a may use a contention-based two-step random access procedure with payload, or a signature-based four step random access procedure with and without contention, which may be implemented in <NUM> and <NUM> symbol length TTIs. In some examples, a UE <NUM>-a may be in connected mode, and may be assigned a cyclic shift to transmit SR. The base station <NUM>-a may reserve a first portion of the signatures within a TTI for SR and a second portion of the signature for PRACH functionality. Such reservations may be, for example, time varying in which the base station <NUM>-a may reserve a time-varying portion of signatures across TTIs for SR functionality and for PRACH functionality. Additionally or alternatively, the signatures reserved for PRACH functionality can be split into contention-based and contention-free resources. The base station <NUM>-a, in some case, may determine which TTIs within frame contain PRACH and provide an indication to the UE <NUM>-a via a periodicity function or a bitmap. Further, in some instances, the base station <NUM>-a may assign signatures to the UE <NUM>-a based on UE characteristics, such that the base station <NUM>-a may intelligently assign users to signatures based on users' likelihood of signature usage (e.g., low likelihood users can occupy cyclic shifts that are closely spaced, or can occupy signatures that have been assigned as contention-based). In some aspects, the base station <NUM>-a may re-use certain signatures for multiple UEs based on a likelihood of the UEs to interfere with each other (e.g., users that can be spatially separated can be assigned cyclic shifts that are closely spaced).

<FIG> illustrates an example of a two-symbol TTI <NUM> that supports SR techniques in wireless transmissions in accordance with various aspects of the present disclosure. In some examples, two-symbol TTI <NUM> may implement aspects of wireless communication system <NUM>. As discussed above, in some cases SR transmissions may be provided using two-symbol TTIs, using a portion of PRACH resources allocated in the two-symbol TTI. In some examples, a SR may be transmitted in a manner similar to existing legacy preamble format <NUM> structure in two OFDM symbols <NUM>, in which a six RB transmission may be provided with a Tseq <NUM>, in which Tseq = <NUM>•Ts, which implies sub carrier spacing of <NUM> and up to <NUM> sequences. For preamble sequence generation, the sequence may be determined according to Equation (<NUM>) below: <MAT> where NZC is the length of the Zadoff-Chu sequence and u is the chosen root of the Zadoff-Chu sequence.

In some cases, Cyclic shifts may be chosen based on a trade-off between capacity and performance, such as according to Equation (<NUM>) below: <MAT> where Cv is a cyclic shift of the Zadoff-Chu sequence and NCS is a set parameter that indicates or limits the set of possible cyclic shifts Cv. In some examples, NCS may be provided to a UE or base station via signaling and by implementing NCS, increased performance in high doppler channels may be achieved at the expense of a lowered maximum capacity of the random access channel.

In some cases, waveform placement may be based on a choice of Tcp <NUM> and Tguard <NUM>, wherein Tcp is the duration of a CP and Tguard is the duration of a guard period. The sum of Tcp <NUM> and Tguard <NUM> may be constrained to be less than <NUM>•Ts based on a duration of two OFDM symbols <NUM>. In such cases, PRACH functionality may be limited to near cell users. For example, for the case of Tguard = <NUM>•Ts, the supportable UE <NUM> to base station <NUM> distance would be about <NUM> meters.

<FIG> illustrates an example of a three symbol TTI <NUM> that supports SR techniques in wireless transmissions in accordance with various aspects of the present disclosure. In some examples, three symbol TTI <NUM> may implement aspects of wireless communication system <NUM>. As discussed above, in some cases SR transmissions may be provided using three-symbol TTIs, using a portion of PRACH resources allocated in the three-symbol TTI. In some examples, two TTIs in each <NUM> subframe may have a length of three OFDM symbols <NUM>. For these TTIs, a larger cell radius can be supported. In some instances, for three OFDM symbols <NUM> the Tseq <NUM> waveform may be <NUM>•Ts, the same as two-symbol case, and may span three symbols with Tcp <NUM> plus Tguard <NUM> being <NUM>•Ts. Relative to the two-symbol case, the CP and guard length increases may support larger cell sizes. For example, in the case of Tguard <NUM> having a duration of <NUM>•TS, the maximum UE to base station distance is about <NUM>. For UEs where the base station to UE distance exceeds this amount, they can revert to using legacy <NUM> PRACH transmissions.

In some cases, such a determination may be based on a timing advance (TA) of the UE. If the base station is given the UE TA value, it may make a determination as to whether shortened PRACH or legacy <NUM> PRACH is to be configured for a given UE. In some examples, a TA value above a threshold value may be used to determine which random access resources are to be used by a UE to transmit SR transmissions. In some instances, a three-symbol TTI may have a sounding reference signal (SRS) transmission in a last symbol of the TTI. In such cases, even though the TTI is a three symbol TTI, the first two symbols can be converted to use the two-symbol PRACH allocation and the last symbol is configured as SRS.

<FIG> illustrates an example of a process flow <NUM> that supports SR techniques in wireless transmissions in accordance with various aspects of the present disclosure. Process flow <NUM> may include a base station <NUM>-b, and a UE <NUM>-b, which may be examples of the corresponding devices described with reference to <FIG> and <FIG>. The base station <NUM>-b and the UE <NUM>-b may establish a connection <NUM> according to established connection establishment techniques for the wireless communications system.

At block <NUM>, the base station <NUM>-b may configure random access resources and SR resources. As discussed above, in some cases base station <NUM>-b may configure PRACH resources within certain TTIs to allow UE <NUM>-b to transmit random access requests. In some examples, the PRACH resources may be allocated such that a first portion of the resource may be allocated for SR transmissions and a second portion of the resources may be allocated for random access transmissions. In some instances, certain preamble signatures may be identified for SR and random access transmissions.

At optional block <NUM>, the UE <NUM>-b may identify its TA. The UE <NUM>-b may in some cases, determine its TA according to established techniques for TA determination, such as based on a round trip time for transmissions between the UE <NUM>-b and base station <NUM>-b. The UE <NUM>- may transmit a TA indication <NUM> to the base station <NUM>-b.

At block <NUM>, the base station <NUM>-b may allocate SR resources and/or preamble signatures to the UE <NUM>-b. In some cases, the SR resources may be allocated based at least in part on the TA value for the UE <NUM>-b, and a distance between the UE <NUM>-b and the base station <NUM>-b. In some examples, SR resources may be allocated based at least in part on a loading of the base station <NUM>-b and how many other users may be present that may need random access resources. In further cases, the base station <NUM>-b may identify a likelihood of the UE <NUM>-b transmitting a SR, and may allocate SR resources based at least in part on the likelihood of such a SR transmission. For instance, if the UE <NUM>-b is a MTC device that has relatively few transmissions, the base station <NUM>-b may allocate SR resources that overlap with one or more other UEs, or may assign UE <NUM>-b a cyclic shift that is closely spaced with other cyclic shifts, or may assign UE <NUM>-b signatures that have been assigned as contention-based. The base station <NUM>-b may transmit configuration information <NUM> to the UE <NUM>-b that may indicate the SR resources. Such configuration information <NUM> may be transmitted using, for example, RRC signaling. In some aspects, the configuration information <NUM> may include a periodicity function or a bitmap that may indicate PRACH resources and SR resources within the PRACH resources.

At block <NUM>, the UE <NUM>-b may determine that uplink resources are needed. For example, the UE <NUM>-b may receive data from an application running at the UE <NUM>-b that is to be transmitted in an uplink transmission, and for which the UE <NUM>-b has not been allocated resources. In some cases, as discussed above, if the UE <NUM>-b also have HARQ ACK/NACK feedback to transmit, the SR may be transmitted using PUCCH resources associated with the HARQ feedback. In cases where the UE <NUM>-b does not have ACK/NACK to transmit, SR resources within the random access resources may be used for the SR transmission. At block <NUM>, the UE <NUM>-b may generate the SR using the SR resources, and may transmit the SR <NUM> to the base station <NUM>-b.

The base station <NUM>-b may receive the SR <NUM>, and at block <NUM> may allocate uplink resources to the UE <NUM>-b for uplink transmissions. The allocated uplink resources may be provided to the UE <NUM>-b in an uplink grant <NUM> that may be transmitted to the UE <NUM>-b.

<FIG> shows a block diagram <NUM> of a wireless device <NUM> that supports SR techniques in wireless transmissions in accordance with aspects of the present disclosure. Wireless device <NUM> may be an example of aspects of a UE <NUM> as described herein. Wireless device <NUM> may include receiver <NUM>, UE communications 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 SR techniques in wireless transmissions). 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 receiver <NUM> may utilize a single antenna or a set of antennas.

UE communications manager <NUM> may be an example of aspects of the UE communications manager <NUM> described with reference to <FIG>. UE communications manager <NUM> and/or at least some of its various sub-components may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions of the UE communications manager <NUM> and/or at least some of its various sub-components may be executed by a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a 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 in the present disclosure.

The UE communications manager <NUM> and/or at least some of its various sub-components may be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations by one or more physical devices. In some examples, UE communications manager <NUM> and/or at least some of its various sub-components may be a separate and distinct component in accordance with various aspects of the present disclosure. In other examples, UE communications manager <NUM> and/or at least some of its various sub-components may be combined with one or more other hardware components, including but not limited to an I/O component, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof in accordance with various aspects of the present disclosure.

UE communications manager <NUM> may identify first random access resources within a first duration TTI and second random access resources within a second duration TTI, where the first duration TTI is shorter than the second duration TTI, generate a SR using resources allocated for SRs within the first random access resources, and transmit the SR.

<FIG> shows a block diagram <NUM> of a wireless device <NUM> that supports SR techniques in wireless transmissions in accordance with 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 herein. Wireless device <NUM> may include receiver <NUM>, UE communications 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).

UE communications manager <NUM> may be an example of aspects of the UE communications manager <NUM> described with reference to <FIG>. UE communications manager <NUM> may also include random access resource manager <NUM> and SR generator <NUM>.

Random access resource manager <NUM> may identify first random access resources within a first duration TTI and second random access resources within a second duration TTI, where the first duration TTI is shorter than the second duration TTI. In some cases, the random access resources may include a cyclic shift that is received in in RRC signaling from a base station. In some examples, the random access resource manager <NUM> may identify which of a set of first duration TTIs include the first random access resources based on configuration information received from a base station, which may include a subset of available preamble signatures associated with the first random access resources. In some examples, the first random access resources may be identified according to a two-OFDM symbol TTI configuration rather than a three-OFDM symbol TTI configuration. In some instances, the first random access resources include a first subset of resources corresponding to the resources allocated for SRs and a second subset of resources allocated for random access requests. In some aspects, the configuration information includes one or more of a periodicity function or a bitmap for determining which of the set of first duration TTIs include the first random access resources. In some instances, the first duration TTI spans three OFDM symbols, and it may be determined that a reference signal is to be transmitted in a last OFDM symbol of the first duration TTI, and the remaining two OFDM symbols used to determine SR resources.

SR generator <NUM> may generate a SR using resources allocated for SRs within the first random access resources, and transmit the SR. In some cases, SR generator <NUM> may generate a second SR using second random access resources within the second duration TTI, and generate the second SR using resources within a control channel allocated for the feedback transmission. In some examples, the second duration TTI corresponds to a one millisecond TTI duration.

<FIG> shows a block diagram <NUM> of a UE communications manager <NUM> that supports SR techniques in wireless transmissions in accordance with aspects of the present disclosure. The UE communications manager <NUM> may be an example of aspects of a UE communications manager <NUM>, a UE communications manager <NUM>, or a UE communications manager <NUM> described with reference to <FIG>, <FIG>, and <FIG>. The UE communications manager <NUM> may include random access resource manager <NUM>, SR generator <NUM>, preamble manager <NUM>, TA component <NUM>, and feedback manager <NUM>. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses).

Random access resource manager <NUM> may identify first random access resources within a first duration TTI and second random access resources within a second duration TTI, where the first duration TTI is shorter than the second duration TTI. In some cases, the random access resources may include a cyclic shift that is received in in RRC signaling from a base station. In some examples, the random access resource manager <NUM> may identify which of a set of first duration TTIs include the first random access resources based on configuration information received from a base station, which may include a subset of available preamble signatures associated with the first random access resources. In some instances, the first random access resources may be identified according to a two-OFDM symbol TTI configuration rather than a three-OFDM symbol TTI configuration. In some aspects, the first random access resources include a first subset of resources corresponding to the resources allocated for SRs and a second subset of resources allocated for random access requests. In some examples, the configuration information includes one or more of a periodicity function or a bitmap for determining which of the set of first duration TTIs include the first random access resources. In some examples, the first duration TTI spans three OFDM symbols, and it may be determined that a reference signal is to be transmitted in a last OFDM symbol of the first duration TTI, and the remaining two OFDM symbols used to determine SR resources.

Preamble manager <NUM> may generate a preamble for the SR transmission. In some cases, the first subset of resources include a first subset of random access preamble signatures for transmitting SRs and the second subset of resources include a second subset of random access preamble signatures for transmitting random access requests. In some examples, the first subset of resources and the second subset of resources are time-varying across a set of first duration TTIs. In some examples, the second subset of resources is split to include contention-based resources and contention-free resources. In some aspects, the first random access resources include a set of available preamble signatures for a four-step random access procedure used for the SR. In some instances, the first random access resources include a first preamble signature for use in transmitting the SR, the first preamble signature selected based on a likelihood of signature usage. In some cases, one or more of a cyclic shift spacing between the first preamble signature and one or more other preamble signatures or a contention category of the first preamble signature is selected based on the likelihood of signature usage. In some examples, one or more of a cyclic shift spacing between the first preamble signature and one or more other preamble signatures or a contention category of the first preamble signature is selected based on a spatial separation of transmitters that may concurrently transmit using the first random access resources.

TA component <NUM> may determine a TA value for transmissions between a UE and a base station, and provide the TA value to the base station. The first duration TTI that includes the first random access resources may selected from two or more TTI durations that are shorter than the second duration TTI based on the TA, in some examples. In some cases, the two or more TTI durations include a two-symbol TTI duration and a three-symbol TTI duration, and the three-symbol TTI duration is selected responsive to the TA value exceeding a first threshold value. In some instances, it may be determined that the TA value exceeds a second threshold value, and a <NUM> TTI may be used for a SR transmission. Feedback manager <NUM> may determine that a feedback transmission is to be transmitted to the base station to indicate successful or unsuccessful reception of a received transmission. In some aspects, if a SR and feedback transmissions are both present, uplink control channel resources used for feedback transmissions may also be used for the SR transmission.

<FIG> shows a diagram of a system <NUM> including a device <NUM> that supports SR techniques in wireless transmissions in accordance with 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> and <FIG>. Device <NUM> may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including UE communications 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 buses (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 DSP, a central processing unit (CPU), a microcontroller, an ASIC, a 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 SR techniques in wireless transmissions).

Software <NUM> may include code to implement aspects of the present disclosure, including code to support SR techniques in wireless transmissions. 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.

However, in some examples the device may have more than one antenna <NUM>, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

In some examples, I/O controller <NUM> may utilize an operating system such as iOS®, ANDROID®, MS-DOS®, MS-WINDOWS®, OS/<NUM>®, UNIX®, LINUX®, or another known operating system. In some instances, I/O controller <NUM> may be implemented as part of a processor. In some aspects, a user may interact with device <NUM> via I/O controller <NUM> or via hardware components controlled by I/O controller <NUM>.

<FIG> shows a block diagram <NUM> of a wireless device <NUM> that supports SR techniques in wireless transmissions in accordance with aspects of the present disclosure. Wireless device <NUM> may be an example of aspects of a base station <NUM> as described herein. Wireless device <NUM> may include receiver <NUM>, base station communications 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 communications manager <NUM> may be an example of aspects of the base station communications manager <NUM> described with reference to <FIG>. Base station communications manager <NUM> and/or at least some of its various sub-components may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions of the base station communications manager <NUM> and/or at least some of its various sub-components may be executed by a general-purpose processor, a DSP, an ASIC, a FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure.

The base station communications manager <NUM> and/or at least some of its various sub-components may be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations by one or more physical devices. In some examples, base station communications manager <NUM> and/or at least some of its various sub-components may be a separate and distinct component in accordance with various aspects of the present disclosure. In other examples, base station communications manager <NUM> and/or at least some of its various sub-components may be combined with one or more other hardware components, including but not limited to an I/O component, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof in accordance with various aspects of the present disclosure.

Base station communications manager <NUM> may identify first random access resources within a first duration TTI and second random access resources within a second duration TTI, where the first duration TTI is shorter than the second duration TTI, allocate SR resources within the first random access resources for use by at least one UE, and receive a SR from the UE over the SR resources.

<FIG> shows a block diagram <NUM> of a wireless device <NUM> that supports SR techniques in wireless transmissions in accordance with aspects of the present disclosure. Wireless device <NUM> may be an example of aspects of a wireless device <NUM> or a base station <NUM> as described with reference to <FIG>. Wireless device <NUM> may include receiver <NUM>, base station communications 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 communications manager <NUM> may be an example of aspects of the base station communications manager <NUM> described with reference to <FIG>. Base station communications manager <NUM> may also include random access resource manager <NUM> and SR resource manager <NUM>.

Random access resource manager <NUM> may identify first random access resources within a first duration TTI and second random access resources within a second duration TTI, where the first duration TTI is shorter than the second duration TTI. In some cases, the first random access resources include a first subset of resources for use in transmitting SRs and a second subset of resources for use in transmitting random access requests. In some examples, the first subset of resources include a first subset of random access preamble signatures for transmitting SRs and the second subset of resources include a second subset of random access preamble signatures for transmitting random access requests. In some instances, the first subset of resources and the second subset of resources are time-varying across a set of first duration TTIs. In some aspects, the second subset of resources is split to include contention-based resources and contention-free resources. In some examples, the first random access resources include a set of available preamble signatures for a four-step random access procedure used for the SR.

SR resource manager <NUM> may allocate SR resources within the first random access resources for use by at least one UE. In some cases, SR resource manager <NUM> may configure the UE to use the first set of random access resources rather than the second set of random access resources in a three OFDM symbol TTI when a periodic reference signal is to be transmitted in a last OFDM symbol of the three OFDM symbol TTI, configure the UE to transmit SRs using a control channel allocated for feedback transmission when the UE has a feedback transmission to be transmitted along with the SR, and receive a SR from the UE over the SR resources. In some examples, the SR resources include a cyclic shift for use when transmitting the SR. In some instances, the allocating further includes: configuring one or more of a periodicity function or a bitmap at the UE to determine which of a set of first duration TTIs include the first random access resources. In some aspects, the first random access resources include a first preamble signature for use in transmitting the SR, the first preamble signature selected based on a likelihood of signature usage. In some cases, one or more of a cyclic shift spacing between the first preamble signature and one or more other preamble signatures or a contention category of the first preamble signature is selected based on the likelihood of signature usage. In some examples, one or more of a cyclic shift spacing between the first preamble signature and one or more other preamble signatures or a contention category of the first preamble signature is selected based on a spatial separation of UEs that may concurrently transmit using the first random access resources. In some instances, the allocating further includes: configuring a first set of random access resources for TTIs having a duration of two orthogonal frequency division multiplexing (OFDM) symbols and a second set of random access resources for TTIs having a duration of three OFDM symbols. In some aspects, the SR resources include a subset of available preamble signatures associated with the first random access resources.

<FIG> shows a block diagram <NUM> of a base station communications manager <NUM> that supports SR techniques in wireless transmissions in accordance with aspects of the present disclosure. The base station communications manager <NUM> may be an example of aspects of a base station communications manager <NUM> described with reference to <FIG>, <FIG>, and <FIG>. The base station communications manager <NUM> may include random access resource manager <NUM>, SR resource manager <NUM>, RRC component <NUM>, and TA component <NUM>. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses).

Random access resource manager <NUM> may identify first random access resources within a first duration TTI and second random access resources within a second duration TTI, where the first duration TTI is shorter than the second duration TTI. In some cases, the first random access resources include a first subset of resources for use in transmitting SRs and a second subset of resources for use in transmitting random access requests. In some examples, the first subset of resources include a first subset of random access preamble signatures for transmitting SRs and the second subset of resources include a second subset of random access preamble signatures for transmitting random access requests. In some instances, the first subset of resources and the second subset of resources are time-varying across a set of first duration TTIs. In some aspects, the second subset of resources is split to include contention-based resources and contention-free resources. In some cases, the first random access resources include a set of available preamble signatures for a four-step random access procedure used for the SR.

SR resource manager <NUM> may allocate SR resources within the first random access resources for use by at least one UE. In some cases, SR resource manager <NUM> may configure the UE to use the first set of random access resources rather than the second set of random access resources in a three OFDM symbol TTI when a periodic reference signal is to be transmitted in a last OFDM symbol of the three OFDM symbol TTI, configure the UE to transmit SRs using a control channel allocated for feedback transmission when the UE has a feedback transmission to be transmitted along with the SR, and receive a SR from the UE over the SR resources. In some examples, the SR resources include a cyclic shift for use when transmitting the SR. In some instances, the allocating further includes: configuring one or more of a periodicity function or a bitmap at the UE to determine which of a set of first duration TTIs include the first random access resources. In some aspects, the first random access resources include a first preamble signature for use in transmitting the SR, the first preamble signature selected based on a likelihood of signature usage. In some cases, one or more of a cyclic shift spacing between the first preamble signature and one or more other preamble signatures or a contention category of the first preamble signature is selected based on the likelihood of signature usage. In some examples, one or more of a cyclic shift spacing between the first preamble signature and one or more other preamble signatures or a contention category of the first preamble signature is selected based on a spatial separation of UEs that may concurrently transmit using the first random access resources. In some instances, the allocating further includes: configuring a first set of random access resources for TTIs having a duration of two OFDM symbols and a second set of random access resources for TTIs having a duration of three OFDM symbols. In some aspects, the SR resources include a subset of available preamble signatures associated with the first random access resources.

RRC component <NUM> may transmit the cyclic shift to the UE using RRC signaling. TA component <NUM> may receive a TA value for transmissions of the UE, select the first duration TTI from two or more TTI durations that are shorter than the second duration TTI based on the TA value, determine that the TA value exceeds a second threshold value, and configure the UE to use the second random access resources within the second duration TTI for SR transmissions. In some cases, the two or more TTI durations include a two-symbol TTI duration and a three-symbol TTI duration, and the three-symbol TTI duration is selected responsive to the TA value exceeding a first threshold value. In some examples, the second duration TTI corresponds to a one millisecond TTI duration.

<FIG> shows a diagram of a system <NUM> including a device <NUM> that supports SR techniques in wireless transmissions in accordance with 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 communications manager <NUM>, processor <NUM>, memory <NUM>, software <NUM>, transceiver <NUM>, antenna <NUM>, network communications manager <NUM>, and inter-station communications manager <NUM>. These components may be in electronic communication via one or more buses (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, a 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 SR techniques in wireless transmissions).

Inter-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>. In some examples, inter-station communications manager <NUM> may provide an X2 interface within an LTE/LTE-A wireless communication network technology to provide communication between base stations <NUM>.

<FIG> shows a flowchart illustrating a method <NUM> for SR techniques in wireless transmissions in accordance with aspects of the present disclosure. The operations of method <NUM> is implemented by a UE <NUM> or its components as described herein. For example, the operations of method <NUM> may be performed by a UE communications 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 device to perform the functions described below. Additionally or alternatively, the UE <NUM> may perform aspects of the functions described below using special-purpose hardware.

At block <NUM> the UE <NUM> identifies first random access resources within a first duration TTI and second random access resources within a second duration TTI, where the first duration TTI is shorter than the second duration TTI. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a random access resource manager as described with reference to <FIG>.

At block <NUM> the UE <NUM> generates a SR using resources allocated for SRs within the first random access resources. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a SR generator as described with reference to <FIG>.

At block <NUM> the UE <NUM> transmits the SR. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a SR generator as described with reference to <FIG>.

<FIG> shows a flowchart illustrating a method <NUM> for SR techniques in wireless transmissions in accordance with 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 communications 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 device to perform the functions described below. Additionally or alternatively, the UE <NUM> may perform aspects of the functions described below using special-purpose hardware.

At block <NUM> the UE <NUM> may identify first random access resources within a first duration TTI and second random access resources within a second duration TTI, where the first duration TTI is shorter than the second duration TTI. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a random access resource manager as described with reference to <FIG>.

At block <NUM> the UE <NUM> may determine a TA value for transmissions between a UE and a base station. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a TA component as described with reference to <FIG>.

At block <NUM> the UE <NUM> may provide the TA value to the base station, and where the first duration TTI that includes the first random access resources is selected from two or more TTI durations that are shorter than the second duration TTI based at least in part on the TA value. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a TA component as described with reference to <FIG>.

At block <NUM> the UE <NUM> may generate a SR using resources allocated for SRs within the first random access resources. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a SR generator as described with reference to <FIG>.

At block <NUM> the UE <NUM> may transmit the SR. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a SR generator as described with reference to <FIG>.

At block <NUM> the UE <NUM> may determine that a second SR is to be transmitted to a base station. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a SR generator as described with reference to <FIG>.

At block <NUM> the UE <NUM> may determine that a feedback transmission is to be transmitted to the base station to indicate successful or unsuccessful reception of a received transmission. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a feedback manager as described with reference to <FIG>.

At block <NUM> the UE <NUM> may generate the second SR using resources within a control channel allocated for the feedback transmission. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a SR generator as described with reference to <FIG>.

At block <NUM> the UE <NUM> may receive an indication of the resources allocated for SRs within first random access resources from a base station, the resources allocated for SRs comprising a subset of available preamble signatures associated with the first random access resources. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a random access resource manager as described with reference to <FIG>.

<FIG> shows a flowchart illustrating a method <NUM> for SR techniques in wireless transmissions in accordance with aspects of the present disclosure. The operations of method <NUM> is 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 communications manager as described with reference to <FIG>. In some examples, a 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 of the functions described below using special-purpose hardware.

At block <NUM> the base station <NUM> identifies first random access resources within a first duration TTI and second random access resources within a second duration TTI, where the first duration TTI is shorter than the second duration TTI. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a random access resource manager as described with reference to <FIG>.

At block <NUM> the base station <NUM> allocates SR resources within the first random access resources for use by at least one UE. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a SR resource manager as described with reference to <FIG>.

At block <NUM> the base station <NUM> receives a SR from the UE over the SR resources. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a SR resource manager as described with reference to <FIG>.

<FIG> shows a flowchart illustrating a method <NUM> for SR techniques in wireless transmissions in accordance with 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 communications manager as described with reference to <FIG>. In some examples, a 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 of the functions described below using special-purpose hardware.

At block <NUM> the base station <NUM> may identify first random access resources within a first duration TTI and second random access resources within a second duration TTI, where the first duration TTI is shorter than the second duration TTI. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a random access resource manager as described with reference to <FIG>.

At block <NUM> the base station <NUM> may allocate SR resources within the first random access resources for use by at least one UE. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a SR resource manager as described with reference to <FIG>.

At block <NUM> the base station <NUM> may receive a TA value for transmissions of the UE. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a TA component as described with reference to <FIG>.

At block <NUM> the base station <NUM> may select the first duration TTI from two or more TTI durations that are shorter than the second duration TTI based at least in part on the TA value. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a TA component as described with reference to <FIG>.

At block <NUM> the base station <NUM> may determine that the TA value exceeds a second threshold value. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a TA component as described with reference to <FIG>.

At block <NUM> the base station <NUM> may configure the UE to use the second random access resources within the second duration TTI for SR transmissions. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a TA component as described with reference to <FIG>.

At block <NUM> the base station <NUM> may configure the UE to transmit SRs using a control channel allocated for feedback transmission when the UE has a feedback transmission to be transmitted along with the SR. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a SR resource manager as described with reference to <FIG>.

At block <NUM> the base station <NUM> may receive a SR from the UE over the SR resources. The operations of block <NUM> may be performed according to the methods described herein. In certain examples, aspects of the operations of block <NUM> may be performed by a SR resource manager as described with reference to <FIG>.

The terms "system" and "network" are often used interchangeably.

In LTE/LTE-A networks, including such networks described herein, the term 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 or NR network in which different types of eNBs provide coverage for various geographical regions. For example, each eNB, next generation NodeB (gNB), 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) 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, eNB, gNB, 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, gNBs, relay base stations, and the like. There may be overlapping geographic coverage areas for different technologies.

A small cell is a lower-powered base station, as compared with a macro cell, that may operate in the same or different (e.g., licensed, unlicensed) frequency bands as macro cells.

Each communication link described herein-including, for example, wireless communications systems <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).

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.

The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a DSP, an ASIC, a 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.

Claim 1:
A method (<NUM>) for wireless communication by a user equipment, UE (<NUM>), comprising:
identifying (<NUM>) first random access resources within a first duration transmission time interval, TTI, and second random access resources within a second duration TTI, wherein the first duration TTI is shorter than the second duration TTI;
generating (<NUM>) a scheduling request using resources allocated for scheduling requests within the first random access resources, wherein the first random access resources comprise a first preamble signature for use in transmitting the scheduling request, wherein a cyclic shift spacing between the first preamble signature and one or more other preamble signatures is selected based at least in part on a likelihood of signature usage; and
transmitting (<NUM>) the scheduling request.