Adaptive resource management for robust communication in new radio

The present disclosure provides for adaptive resource management in new radio operations that favors the usage of resources for pilot signals and channel estimation in the transition slots of a slot burst, and the transmission of data in the subsequent slots of the slot burst. A device such as a user equipment (UE) and/or a base station may determine that the UE is operating in a transition state. The device may adapt a first numerology including a first number of symbols per slot used for transmission in the transition slots during the transition state, to a second scaled numerology including a second number of symbols per slot used for transmission in the subsequent slots after the transition state. A ratio of reference signal symbols to data symbol symbols may be greater in the transition slots than in the subsequent slots.

BACKGROUND

Aspects of this disclosure relate generally to telecommunications, and more particularly to resource management in wireless communication systems.

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and single-carrier frequency division multiple access (SC-FDMA) systems.

These 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. For example, 5G new radio (NR) communications technology is envisaged to expand and support diverse usage scenarios and applications with respect to current mobile network generations. In an aspect, 5G communications technology includes enhanced mobile broadband addressing human-centric use cases for access to multimedia content, services and data; ultra-reliable-low latency communications (URLLC) with strict requirements, especially in terms of latency and reliability; and massive machine type communications for a very large number of connected devices and typically transmitting a relatively low volume of non-delay-sensitive information. As the demand for mobile broadband access continues to increase, however, there exists a need for further improvements in 5G communications technology and beyond. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

It is envisaged that 5G NR will, in some cases, be deployed in time division duplexing (TDD) bands using very large spectrum (e.g., greater than 100 MHz). Due to the large spectrum, devices may be able to complete transmission of available data relatively quickly. Accordingly, the transmission pattern for 5G NR may be bursty in nature. The bursty transmission pattern allows the user equipment (UE) to more frequently utilize a sleep operation (e.g., discontinuous reception (DRX)) for power savings. The UE may be in a sleep state, then wake up for a short period of time to receive and/or transmit data, then return to the sleep state.

Network capacity improvements by 5G communications technology in terms of, for example, spectral and energy efficiency may nonetheless adversely impact some aspects of existing technologies. For example, it is well known that orthogonal frequency-division multiplexing (OFDM) systems and single carrier frequency-division multiplexing (SC-FDM) system are relatively sensitive to noise and interference. Particularly, in order to transfer data correctly between the UE and a network, the UE and the base station (e.g., evolved Node B), generally use channel estimation to filter out noise and/or interference. In bursty transmission patterns, however, there may not be enough time for enhancing the channel estimates through across-slot filtering. For example, a UE may wake up for only a few slots. By the time the UE and base station transmit enough reference signals to build channel estimation filters, the burst may be complete.

SUMMARY

The present disclosure provides for adaptive resource management that favors the usage of resources for pilot signals and channel estimation in the first slots of a slot burst, and the transmission of data in the later slots of a slot burst.

In an aspect, the disclosure provides a method of resource adaptation for wireless communications. The method includes determining that a UE is operating in a transition state. The method also includes transmitting, using a first numerology including a first number of symbols per slot, a first transmission having a first ratio of reference signal symbols to data symbols, for at least one transition slot while the UE is operating in the transition state. The method further includes adapting the first numerology, in a subsequent slot after the transition state, to a scaled numerology including a second number of symbols per slot, according to a defined adaptation schedule. The method additionally includes transmitting, using the scaled numerology, a second transmission having a second ratio of reference signal symbols to data symbols, in the subsequent slot. The first ratio may be greater than the second ratio.

In another aspect, the disclosure provides an apparatus for wireless communications. The apparatus includes a processor and a memory coupled to the processor. The memory includes instructions executable by the processor to determine that a UE is operating in a transition state. The processor is further configured to transmit, using a first numerology including a first number of symbols per slot, a first transmission having a first ratio of reference signal symbols to data symbols, for at least one transition slot while the UE is operating in the transition state. The processor is further configured to adapt the first numerology, in a subsequent slot after the transition state, to a second scaled numerology including a second number of symbols per slot according to a defined adaptation schedule. The processor is further configured to transmit, using the second scaled numerology, a second transmission having a second ratio of reference signal symbols to data symbols, in the subsequent slot, wherein the first ratio is greater than the second ratio.

In another aspect, the disclosure provides another apparatus for wireless communication. The apparatus includes means for determining that a UE is operating in a transition state. The apparatus further includes means for transmitting, using a first numerology including a first number of symbols per slot, a first transmission having a first ratio of reference signal symbols to data symbols, for at least one transition slot while the UE is operating in the transition state. The apparatus further includes means for adapting the first numerology, in a subsequent slot after the transition state, to a scaled numerology including a second number of symbols per slot, according to a defined adaptation schedule. The means for transmitting may also be configured to transmit, using the scaled numerology, a second transmission having a second ratio of reference signal symbols to data symbols, in the subsequent slot. The first ratio may be greater than the second ratio.

In another aspect, the disclosure provides a computer readable medium for wireless communication. The computer readable medium includes code for determining that a UE is operating in a transition state. The computer readable medium includes code for transmitting, using a first numerology including a first number of symbols per slot, a first transmission having a first ratio of reference signal symbols to data symbols, for at least one transition slot while the UE is operating in the transition state. The computer readable medium includes code for adapting the first numerology, in a subsequent slot after the transition state, to a scaled numerology including a second number of symbols per slot, according to a defined adaptation schedule. The computer readable medium includes code for transmitting, using the scaled numerology, a second transmission having a second ratio of reference signal symbols to data symbols, in the subsequent slot. The first ratio may be greater than the second ratio.

DETAILED DESCRIPTION

As discussed above, emerging 5G or New Radio (NR) communications technology, may employ large spectrum and have a bursty transmission pattern. The transmission pattern may be organized as a series of slots. As used herein, the term “slot” may refer to a time period during which a UE may be scheduled for communication. For example, the time period referred to as a “subframe” in 4G/LTE terminology may be considered a slot. In 5G/NR a slot may have a different duration depending on a current configuration. Slots may be a self-contained and do not necessarily rely on a fixed frame structure to define the contents or format of a slot.

Generally, existing technologies utilize channel estimation filters to improve reception of signals by filtering out noise and interference by averaging or generally performing across-slot channel estimation procedures. In the case of bursty transmissions, such channel estimation filters may become outdated during a sleep operation and no longer be effective. When the next burst starts, the channel estimation filters may not have enough time to become as effective before the UE returns to the sleep operation. Similarly, when the UE is experiencing varying channel conditions (e.g., high Doppler effects), channel estimation filters may also be ineffective.

One technique for improving channel estimation filters in the case of bursty communications is to provide special wake-up slots including additional sounding reference signals (SRS). The wake-up slots may be uplink centric slots in a TDD transmission pattern. The additional SRS allows the base station to more quickly build a channel estimation filter. In an aspect, the channel estimation filter may improve the ability of the base station to correctly decode a transmission from the UE, especially for single bit control information such as acknowledgments (ACK) or negative acknowledgments (NACK). For example, the use of channel estimation filters may decrease the required signal-to-noise ratio (SNR) or signal-to-noise plus interference ratio (SINR) for reliable reception of ACK/NACK by several decibels (dB). The use of wake-up slots, however, may not be as effective or efficient in the case of short bursts.

In an aspect, the present disclosure provides for adaptive resource management that favors the usage of resources for pilot signals and channel estimation in the first slots of a burst and the transmission of data in the later slots of the burst. The first slots in the burst may be referred to as transition slots or cold-start slots and the UE may be considered to be operating in a transition state when transmitting or receiving transition slots. Various transmission properties may be adjusted by both the UE and the base station as the UE switches from the transition state to transmit in a normal state in subsequent slots. The adjustment of the transmission properties may be according to a defined schedule. The schedule may be defined in a standard, configured for an individual UE via physical layer signaling (e.g., a physical downlink control channel (PDCCH)) or higher layer signaling (e.g., radio resource control), or broadcast by the base station (e.g., in system information blocks (SIB)). In an aspect, transmission properties that may be adapted between transition slots and subsequent slots include a numerology, transmission powers for various channels, symbol waveforms, and time density and/or frequency density of reference signals.

Various aspects are now described in more detail with reference to theFIGS. 1-10. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects. It may be evident, however, that such aspect(s) may be practiced without these specific details. Additionally, the term “component” as used herein may be one of the parts that make up a system, may be hardware, firmware, and/or software stored on a computer-readable medium, and may be divided into other components.

Referring toFIG. 1, in accordance with various aspects of the present disclosure, an example wireless communication network100includes at least one UE110having a transition component160configured to perform one or more techniques described herein. A base station105may also include a transition component160configured to perform similar or complementary techniques described herein at the base station105.

In particular, transition component160may include a detection component165configured to determine whether the UE110is operating in a transition state. Generally, the UE may operate in a transition state whenever the UE or the base station does not have an effective channel estimation filter. For example, the channel estimation filter may be out of date due to a period of inactivity or due to changing channel conditions. Specifically, detection component165may determine whether the UE is operating in a transition state according to one or more defined rules. For example, the UE may operate in a transition state when the UE110first establishes a connection with the base station. As another example, the UE may operate in a transition state when the UE110exits a DRX mode. In another example, the UE may operate in the transition state when the UE or base station determines that a channel estimation filter is not effective. For example, the UE or base station may detect a number or percentage of reception failures or detect a metric (e.g., Doppler shift) that indicates changing channel conditions. The base station105may signal to the UE110that the UE110should switch to the transition state. The detection component165at the UE110may detect signals from the base station105.

The transition state may be a defined number of slots (e.g., 1-5). The number of slots may be defined according to a schedule. During the transition state, the UE110and/or the base station105may adapt transmission properties. In an aspect, one or more transmission properties may have a first value during the transition state and a different value in a slot subsequent to the transition state. In another aspect, where the transition state includes multiple slots, the one or more transmission properties may also be adapted between slots of the transition state. The transmission properties may not change once the UE110has left the transition state. For example, a scaled numerology may be adapted during the transition state to allow a gradual decrease in a ratio of reference signal symbols to data symbols. Once the UE110leaves the transition state, the UE110may no longer adapt the transmission property. The one or more transmission properties used for the subsequent slot may be used for remaining slots in the slot burst.

In some examples of the present disclosure, the transition component160may further include adaptation component170for adapting a first transmission property used in the transition state to a second transmission property in a slot subsequent to the transition state. After the UE110has transmitted or received the one or more transition slots using a first transmission property, the adaptation component170may change the first transmission property to a second transmission property. Adapting or changing the transmission property may involve an adaptation or change in the characteristics, features, or attributes of a property, including an adaptation or a change in the value. For example, the adaptation component170may change the transmission power of one or more channels. As another example, the adaptation component170may change a numerology and/or a ratio of reference signal symbols to data symbols. In another aspect, the adaptation component170may change the waveform of a specific symbol. In another aspect, the adaptation component170may change a ratio of reference signal resource elements to data resource elements.

In an aspect, the adaptation component170may optionally include power component172for adapting a transmission power of the UE110or base station105. In a transition slot, the UE110may transmit specific signals or channels with a higher power if the UE110is not set to transmit with a maximum power based on current conditions. For example, the UE110may transmit physical layer channels that typically carry pilot signals such as the SRS and/or physical channels that carry payload such as PUCCH or PUSCH with higher power in the transition slots. The base station105may also adapt its transmission power for transition slots. For example, the base station105may transmit physical layer channels including pilots such as sounding reference signal (SRS). a demodulation reference signal (DMRS), a cell reference signal (CRS), and/or physical layer channels that carry a payload such as a physical downlink shared channel (PDSCH), and/or a physical downlink control channel (PDCCH) with a higher transmission power. As another example, a reference signal (RS) bearing channel and a data-bearing channel may be boosted, or one of the channels may be boosted in comparison to a transmission power in a subsequent slot. In any case, the UE110and base station105may agree on an RS/Data power ratio, which may be determined according to the adaptation schedule. Further, the power component172may adapt a change in transmission power (“delta”) applied to the transmission power based on the adaptation schedule. For example, during the transition state, the UE110may increase or decrease the transmit power in steps of 3 decibels (dB), whereas in the subsequent slots the UE110may increase or decrease the transmit power in steps of 1 dB for the same power control command. Accordingly, the interpretation of the power control commands may be adapted between slots. Further, the adaptation schedule may establish a base transmit power. The base transmission power may be based on a transmission power used prior to a DRX state. The base transmission power may also be signaled to the UE110via PDCCH, a SIB, or higher layer signaling. Additionally, the adaptation schedule with respect to power adaptation across slots may be configurable for an individual UE110, predetermined in a standard, or indicated for all UEs served by the base station105.

In an aspect, the adaptation component170may optionally include numerology component174for adapting a numerology used by the UE110or base station105for transmissions. For example, the numerology component174may adapt a first numerology used for transmissions in a transition state to a second numerology used for transmissions in a subsequent slot after the transition state. As discussed in further detail below, the second numerology may be a scaled numerology. The numerology component174may also adapt a ratio of reference signal symbols to data symbols used in the transition state and/or the subsequent slots. For example, the numerology component174may adjust the ratio such that the ratio is greater during the transition state than during the subsequent slots. Accordingly, transmissions using the greater ratio of reference signal symbols to data symbols may be easier to decode when a channel estimation filter180is not available or is otherwise deficient.

Additionally, the transition component160may further include a transmission component175for transmitting according to the transmission properties determined by the detection component165and/or the adaptation component170. For example, the transmission component175may transmit according to properties determined by the detection component165when the UE110is in the transition state for transition slots. In slots subsequent to the transition state, the transmission component175may transmit according to transmission properties determined by the adaptation component170.

The transition component160may also include a channel estimation filter180for filtering received signals. In an aspect, the channel estimation filter180may become outdated or reset when the UE110experiences an interruption in communications such as entering a DRX state. As the UE begins a new slot burst, the transition component160may build up the channel estimation filter180based on reference signals transmitted in the slots.

The wireless communication network100may include one or more base stations105, one or more UEs110, and a core network115. The core network115may provide user authentication, access authorization, tracking, internet protocol (IP) connectivity, and other access, routing, or mobility functions. The base stations105may interface with the core network115through backhaul links120(e.g., S1, etc.). The base stations105may perform radio configuration and scheduling for communication with the UEs110, or may operate under the control of a base station controller (not shown). In various examples, the base stations105may communicate, either directly or indirectly (e.g., through core network115), with one another over backhaul links125(e.g., X1, etc.), which may be wired or wireless communication links.

The base stations105may wirelessly communicate with the UEs110via one or more base station antennas. Each of the base stations105may provide communication coverage for a respective geographic coverage area130. In some examples, base stations105may be referred to as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, eNodeB (eNB), a gNodeB (gNB), transmit-receive point (TRP), Home NodeB, a Home eNodeB, a relay, or some other suitable terminology. The geographic coverage area130for a base station105may be divided into sectors or cells making up only a portion of the coverage area (not shown). The wireless communication network100may include base stations105of different types (e.g., macro base stations or small cell base stations, described below). Additionally, the plurality of base stations105may operate according to different ones of a plurality of communication technologies (e.g., 5G, 4G/LTE, 3G, Wi-Fi, Bluetooth, etc.), and thus there may be overlapping geographic coverage areas130for different communication technologies.

In some examples, the wireless communication network100may be or include a Long Term Evolution (LTE) or LTE-Advanced (LTE-A) technology network. The wireless communication network100may also be a next generation technology network, such as a 5G wireless communication network. Moreover, the wireless communication network100may support high frequency operations such as millimeter wave communications. In LTE/LTE-A networks, the term evolved node B (eNB) may be generally used to describe the base stations105, while the term UE may be generally used to describe the UEs110. The wireless communication network100may be a heterogeneous LTE/LTE-A network in which different types of eNBs provide coverage for various geographical regions. For example, each eNB or base station105may provide communication coverage for a macro cell, a small cell, or other types of cell. The term “cell” is a 3GPP term that can be used to describe a base station, a carrier or component carrier associated with a base station, or a coverage area (e.g., sector, etc.) of a carrier or base station, depending on context.

A macro cell may generally cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by the UEs110with service subscriptions with the network provider.

A small cell may include a relative lower transmit-powered base station, as compared with a macro cell, that may operate in the same or different frequency bands (e.g., licensed, unlicensed, etc.) as macro cells. Small cells may include pico cells, femto cells, and micro cells according to various examples. A pico cell, for example, may cover a small geographic area and may allow unrestricted access by the UEs110with service subscriptions with the network provider. A femto cell may also cover a small geographic area (e.g., a home) and may provide restricted access and/or unrestricted access by the UEs110having an association with the femto cell (e.g., in the restricted access case, the UEs110in a closed subscriber group (CSG) of the base station105, which may include the UEs110for users in the home, and the like). An eNB for a macro cell may be referred to as a macro eNB. An eNB for a small cell may be referred to as a small cell eNB, a pico eNB, a femto eNB, or a home eNB. An eNB may support one or multiple (e.g., two, three, four, and the like) cells (e.g., component carriers).

The communication networks that may accommodate some of the various disclosed examples may be packet-based networks that operate according to a layered protocol stack and data in the user plane may be based on the IP. A radio link control (RLC) layer may perform packet segmentation and reassembly to communicate over logical channels. A MAC layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use 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 UE110and the base stations105. The RRC protocol layer may also be used for core network115support of radio bearers for the user plane data. At the physical (PHY) layer, the transport channels may be mapped to physical channels.

The UEs110may be dispersed throughout the wireless communication network100, and each UE110may be stationary or mobile. A UE110may also include or be referred to by those skilled in the art 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 UE110may 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 wireless local loop (WLL) station, an entertainment device, a vehicular component, or any device capable of communicating in wireless communication network100. Additionally, a UE110may be Internet of Things (IoT) and/or machine-to-machine (M2M) type of device, e.g., a low power, low data rate (relative to a wireless phone, for example) type of device, that may in some aspects communicate infrequently with wireless communication network100or other UEs. A UE110may be able to communicate with various types of base stations105and network equipment including macro eNBs, small cell eNBs, relay base stations, and the like.

A UE110may be configured to establish one or more wireless communication links135with one or more base stations105. The wireless communication links135shown in wireless communication network100may carry UL transmissions from a UE110to a base station105, or downlink (DL) transmissions, from a base station105to a UE110. The downlink transmissions may also be called forward link transmissions while the uplink transmissions may also be called reverse link transmissions. Each wireless communication link135may include one or more carriers, where each carrier may be a signal made up of multiple subcarriers (e.g., waveform signals of different frequencies) modulated according to the various radio technologies described above. Each modulated signal may be sent on a different subcarrier and may carry control information (e.g., reference signals, control channels, etc.), overhead information, user data, etc. In an aspect, the communication links135may transmit bidirectional communications using frequency division duplex (FDD) (e.g., using paired spectrum resources) or time division duplex (TDD) operation (e.g., using unpaired spectrum resources). Frame structures may be defined for FDD (e.g., frame structure type 1) and TDD (e.g., frame structure type 2). Moreover, in some aspects, the communication links135may represent one or more broadcast channels.

In some aspects of the wireless communication network100, base stations105or UEs110may include multiple antennas for employing antenna diversity schemes to improve communication quality and reliability between base stations105and UEs110. Additionally or alternatively, base stations105or UEs110may employ multiple input multiple output (MIMO) techniques that may take advantage of multi-path environments to transmit multiple spatial layers carrying the same or different coded data.

FIG. 2is an example frame structure200utilizing time-division duplexing. The frame structure200may be used for a burst of traffic in one or both of the uplink or downlink. The frame structure200may include an initial control slot205, which may carry a physical dedicated control channel (PDCCH)205that provides initial control information for the frame structure200. In some examples, the slot205may be broadcasted by the base station105to one or more UEs110within its cell.

The frame structure200may further include slots210,220,230, and240. Each of the slots210,220,230,240, may be subdivided into a plurality of resource blocks (e.g., OFDM or SC-FDM symbols) corresponding to frequency and time domain according to a numerology. As used herein, the term “numerology” may refer to a relation of subcarrier spacing in the frequency domain and a symbol period in the time domain. In an aspect, a mini-slot may refer to a unit of time corresponding to one or more symbol periods. A UE may be scheduled to communicate during a mini-slot within a slot. A numerology may be used for OFDM and/or SC-FDM. As discussed in further detail below, the numerology may be scalable.

Each of the slots may be designated as a downlink centric or uplink centric slot. For example, slot210may be an uplink centric slot210carrying a physical uplink control channel (PUCCH) for carrying control information and a physical uplink shared channel (PUSCH) for carrying data. Slot220may be an example of a downlink centric slot carrying the PDCCH and data (e.g., on a physical downlink shared channel (PDSCH)). The downlink centric slot220may be used primarily for downlink traffic, but may also include an opportunity for the UE110to transmit a sounding reference signal (SRS) and an ACK/NACK in the uplink. In an aspect, the ACK/NACK may be indicated by a selection of the SRS. Each of the slots210,220,230,240may be followed by a guard period separating the subsequent slot from the preceding slot.

In an aspect, slot210may be an example of a warm-up slot. The slot210may include a physical uplink control channel (PUCCH)212followed by a physical uplink shared channel (PUSCH)214. The PUSCH214may be interspersed with additional sounding reference signals (SRS)216. The additional SRS216may be used to build a channel estimation filter at the base station. The slot210may end with a main SRS218, which may be included in every slot regardless of whether the slot is indicated as a warm-up slot.

In an aspect, the slots205,210,220, and230may be considered transition slots250. The UE110may operate in a transition state when receiving and transmitting the transmission slots. The transmission properties of the transition slots250may be adapted between slots. In contrast, the slot240and any further slots in the slot burst may be considered subsequent slots260. The transmission properties of the subsequent slots260may be fixed. That is, certain transmission properties may be adapted during the transition state, but become fixed once the UE110leaves the transition state.

FIG. 3is a conceptual diagram showing an example of scaled numerology for adaptive resource management. A frequency-division numerology may be utilized in an OFDMA system or a SC-FDMA system. In an aspect, in 5G or NR, both OFDMA and SC-FDMA may be utilized for uplink traffic depending on the scenario. For example, OFDMA may be used for UEs that are located relatively close to the base station and SC-FDMA may be used for UEs near a cell edge. SC-FDMA may also be utilized for energy efficiency. The frequency-division numerology defines a subcarrier spacing in the frequency domain and a symbol period in the time domain that divide the available resources into resource elements (RE). The frequency-domain numerology may be identified by the subcarrier spacing. The resource elements may be further grouped into resource blocks (RB).

Scaling a numerology means that the ratio of the scaled subcarrier spacing to a nominal subcarrier spacing equals the ratio of any two positive integers. For example, scaling a numerology may include changing the subcarrier spacing by a power of 2 such that the ratio is ½^k or 2^k, where k is a positive integer. A nominal subcarrier spacing may refer to a lowest subcarrier spacing allowed for a particular radio access technology (RAT). For example, a nominal subcarrier spacing may be a subcarrier spacing for a legacy RAT such as 4G/LTE. As another example, a nominal subcarrier spacing may be an agreed nominal subcarrier spacing and maybe indicated as f0. A nominal subcarrier spacing may also be referred to as a base subcarrier spacing. When the subcarrier spacing is doubled, the symbol period is halved. For example, a nominal subcarrier spacing may be 15 kilohertz (KHz) (f0) and scaled numerologies may have a subcarrier spacing of 30 KHz (2×f0), 60 KHz (4×f0), or 120 Khz (8×f0). Such scaled numerologies may be compatible with the nominal subcarrier spacing because a time period (e.g., a time slot or subframe) may be evenly divided into a greater number of symbols. In an aspect, a scaled numerology may be utilized to provide a finer degree of control over allocation of resources in one or more slots.

As illustrated inFIG. 3, a nominal numerology310having a nominal subcarrier spacing may include a single symbol for a time period350. The single symbol may be used to carry either a reference signal (RS) or data. The single symbol may be repeated on multiple subcarriers. In OFDMA, the symbol may be interleaved with one or more other symbols on the subcarriers. In an aspect, scalable numerology may be used to split differently the time-domain resource (e.g., symbols) in transition slots and subsequent slots. For example, a numerology320having double the subcarrier spacing has half of the symbol period. Accordingly two symbols may be transmitted in the time period350. In an aspect, the symbols may be allocated between reference signals and data. For example, one symbol may be allocated to an RS and the other symbol to data, providing a 1:1 ratio between RS and data. Further scaling the numerology to 4 times the subcarrier spacing provides 4 symbols within the time period350. Different ratios of RS to data may be achieved with the scaled numerology. For example, scaled numerology330allocates three symbols to RS and one symbol to data for a ratio of 3:1. In contrast, scaled numerology330allocates one (1) symbol to RS and three symbols to data for a ratio of 1:3. In an aspect, when the UE110transmits multiple consecutive RS, each symbol may be the same. Accordingly, a cyclic prefix (CP) may be unnecessary for a sequence of consecutive identical RS symbols because one of the other RS symbols may be used as a CP for any of the identical RS symbols.

As discussed above, when the UE110is in a transition state, it may be desirable to provide more RS to help with both decoding of transmitted data as well as building of a channel estimation filter. The additional RS, however, becomes a less efficient use of resources as the channel estimation filter is built. In an aspect, the adaptation component170may adjust the scaled numerology for a portion of a slot. Such that the allocation of RS and data symbols can be adjusted. The adaptation component may also adjust the allocation of RS and data symbols (e.g., by changing a ratio).

FIG. 4illustrates a conceptual diagram showing an example of adaptation of reference signals between slots using a scaled numerology. Each of slots410,420,430, and440may have a different ratio of RS symbols to data symbols. The scaled numerology may be adapted as the transmitted slot transitions from slot410, to slot420, to slot430, to slot440. In an aspect, the slot440may be a slot subsequent to the transition state and the ratio of RS symbols to data symbols used in slot440may be used for all slots subsequent to the transition state in the slot burst. In an aspect, the slot410may be a first slot in a burst and may be considered a transition slot. In the first slot410, the numerology may be scaled such that four (4) symbols may be transmitted within a time period450, which may, for example, correspond to a slot. For example, a nominal subcarrier spacing of N (e.g. 15 KHz) may be scaled by a factor of 4, which is a power of 2, to have a subcarrier spacing of 4N. The time-domain resources may be allocated such that three (3) symbols are allocated to RS and one (1) symbol is allocated to data, giving a ratio of 3:1 of 75% RS. The relatively high ratio of RS may improve decoding of the data when a channel estimation filter is not available.

In the second slot420, the numerology may be further scaled. For example, the nominal subcarrier spacing of N may be scaled by a factor of 8, which is a power of 2, resulting in a subcarrier spacing of 8N and 8 symbols within the time period450. The resources may be allocated such that five (5) symbols are allocated to RS and three (3) symbols are allocated to data. Accordingly, the ratio of RS to data may be 5:3 or 62.5% RS. It may be noted that such a ratio is unavailable with the numerology of slot410(at least in SC-FDM). Accordingly, by changing the numerology, a gradual reduction in the ratio may be achieved.

In slot430, the numerology may be scaled by a different factor. For example, the nominal subcarrier spacing of N may be scaled by a factor of 2, resulting in a subcarrier spacing of 2N and 2 symbols in the time period450. One symbol may be allocated for RS and one symbol may be allocated for data for a ratio of 1:1 or 50% RS. In this example, the scaling is reduced because the lower numerology allows for the desired ratio. In an aspect, a lower numerology or lower slot spacing may be desirable because the lower slot spacing may be more robust to delay spread and/or inter-symbol interference.

The slots410,420,430may be considered part of the transition state and may a transition slot460. Slot440may be considered one of the subsequent slots470. Slot440may be immediately subsequent to the transition slots460. In an aspect, slot440may be followed by additional subsequent slots470. In slot440, the numerology may return to the nominal subcarrier spacing of N being scaled by a factor of 8, resulting in a subcarrier spacing of 8N and 8 symbols within the time period450. Three (3) symbols may be allocated for RS and five (5) symbols may be allocated for data for a ratio of 3:5 or 37.5% RS. The relatively low ratio may allow an increase in the amount of data that may be transmitted in the subsequent slots. The ratio in slot440may be used for each slot within the slot burst that is subsequent to the transition state.

FIG. 5is a conceptual diagram500showing adaptation of tone allocation. Adaptation of tone allocation may be utilized in OFDM transmissions. In a first slot510, RS tones are interleaved with data tones such that alternating tones are RS tones. Accordingly, the ratio of RS tones to data tones is 1:1 or 50% RS. The first slot510may be the first slot in a burst and may be considered a transition slot. In a subsequent slot520, the tone allocation may be changed to decrease the frequency density of the RS tones such that RS tones are interleaved at every fourth tone. Accordingly, in slot520, the ratio of RS tones to data tones is 1:3 or 25% RS. The higher ratio of RS tones in the transition slot510may provide additional reference signals to help decode data. The lower ratio of RS tones in the subsequent slot520may allow more data to be transmitted in the subsequent slot520.

FIG. 6is a conceptual diagram600illustrating adaptation of tone allocation and symbol allocation using scaled numerology. In the slots610and620, the numerology may be scaled in comparison to slots510and520such that two symbols may be transmitted in each slot. In the first slot, every tone of the first symbol may be allocated as an RS tone and in the second symbol, RS tones may be interleaved with data tones. Accordingly, the total ratio of RS tones to data tones for the slot610is 3:1 or 75% RS. The first slot610may be the first slot in a burst and may be considered a transition slot. In the subsequent slot620, the tone allocation may be changed such that in the first symbol, RS tones are interleaved with data tones and in the second symbol all of the tones are data tones. Accordingly, in slot620, the ratio of RS tones to data tones is 3:1 or 75% RS. The higher ratio of RS tones in the transition slot610may provide additional reference signals to help decode data. The lower ratio of RS tones in the subsequent slot620may allow more data to be transmitted in the subsequent slot620. Where a combination of both time and frequency adaptation is possible a desired ratio may be achieved while providing robustness against delay spread and frequency shifts.

FIG. 7is a conceptual diagram700showing adaptation of a waveform of a reference signal. A first slot710may be an example of a downlink centric slot having a downlink portion712and an ACK portion714. The ACK portion714may be used to provide an indication of whether downlink portion712was correctly received. In an aspect, the ACK portion714may include an SRS. The selection of the SRS waveform may indicate ACK or NACK. In the slot710, an ACK may be indicated by a first SRS1and a NACK may be indicated by a second, SRS2having a sequence that is orthogonal to SRS1. In an aspect, SRS1being orthogonal to SRS2may allow the ACK/NACK to be decoded using noncoherent communication. As used herein, noncoherent communication may refer to communications where the receiver does not know the phase of every subcarrier. For example, the receiver may not have built an effective channel estimate filter or phase estimate because the slot710is a transition slot. Because SRS1and SRS2are orthogonal, the difference should be reliably detected, for example, by a metric such as received energy.

Slot720may also be an example of a downlink centric slot including a downlink portion722and an ACK/NACK portion724. Once again, the ACK portion724may be used to provide an indication of whether downlink portion712was correctly received using the selection of the SRS waveform. In slot720, the reliability of the communication may be improved by using coherent communication. In the subsequent slot720, the receiver may have built a coherent filter, for example, based on the SRS in the ACK portion714and/or other reference signals. The ACK portion724may indicate an ACK using a first SRS (e.g., SRS1) and indicate a NACK using a sequence that is the opposite of the first SRS (e.g., −SRS1). Because the phase of each of the subcarriers is known, the receiver may more reliably decode which SRS symbol was transmitted in comparison to a noncoherent communication.

FIG. 8is a flowchart of an example method800of resource adaptation for wireless communications. The method800may be performed using an apparatus (e.g., the UE110or a base station105, for example). Although the method800is described below with respect to the elements of the UE110, other components may be used to implement one or more of the steps described herein.

In block805, the method800may optionally include receiving an indication of an adaptation schedule. In an aspect, the transition component160may receive the indication of the adaptation schedule. For example, the indication may be broadcast by a base station in a system information block (SIB) or transmitted to the UE110in signaling information such as a PDCCH or higher level signaling. The adaptation schedule may be defined by a standard or specification that is followed by the UE110and the base station105. The adaptation schedule may be defined by one or more parameters that may be signaled during operation. For example, the standard may define multiple adaptation schedules and a base station may signal an indication of which adaptation schedule is to be applied by the UE110. In another aspect, an adaptation schedule may include a time period (e.g., a number of slots) that define when adaptation is to occur. The base station105may signal additional parameters that define the adaptation to be applied by the UE110. Accordingly, both the UE110and the base station105may have access to the adaptation schedule and may implement the adaptations at the same time.

In block810, the method800may include determining that a UE is operating in a transition state. In an aspect, for example, the detection component165may determine that the UE110is operating in a transition state. The UE110may operate in the transition state at the start of a transmission burst. For example, the detection component165may determine that the UE has transitioned to a connected mode (e.g. established a connection with the base station105). As another example, the detection component165may determine that the UE110has transitioned from a discontinuous reception (DRX) state. As another example, the detection component165may determine that the UE110is experiencing changing channel conditions (e.g., by analyzing channel metrics). As another example, the detection component165may determine that a channel estimation filter is unreliable (e.g., by evaluating the sources for or performance of the channel estimation filter). The detection component165may request the transition state from the base station105in response to experiencing changing channel conditions or determining that a channel estimation filter is unreliable. The base station105may also determine that the UE is operating in a transition state. The base station105may determine when the UE transitions to the connected mode or transitions from the DRX state. Additionally, the base station105may signal the UE110to enter the transition state based on conditions detected by the base station105. Further details regarding determining that a UE is operating in a transition state are described below with respect toFIG. 9.

In block815, the method800may include transmitting using a first numerology including a first number of symbols per slot, a first transmission having a first ratio of reference signal symbols to data symbols, for at least one transition slot while the UE is operating in the transition state. In an aspect, the transmission component175at either the UE110or base station105may transmit, using the first numerology including the first number of symbols per slot, the first transmission having the first ratio of reference signal symbols to data symbols, for the at least one transition slot while the UE is operating in the transition state. For example, the transmission component175at the UE110may transmit the first transmission, and the base station105may receive the first transmission according to the first numerology. Conversely, the transmission component175at the base station105may transmit the first transmission, and the UE110may receive the first transmission according to the first numerology. Accordingly, the first transmission may be between the UE110and the base station105in either the uplink direction or the downlink direction. The first numerology may be determined by the numerology component174based on the transition state and the adaptation schedule. Generally, the first numerology may favor usage of resources for pilot signals and channel estimation. For example, the first numerology may allow a relative increase in the ratio of reference symbols to data symbols during the transition state as compared to during subsequent slots.

In block820, the method800may include adapting the first numerology, in a subsequent slot after the transition state, to a second scaled numerology including a second number of symbols per slot, according to a defined adaptation schedule. In an aspect, for example, the numerology component174may adapt the first numerology, in the subsequent slot after the transition state, to the second scaled numerology including the second number of symbols per slot according to the defined adaptation schedule. The adaptation schedule may be the adaptation schedule indicated in block805. By changing the number of symbols per slot, the adaptation component170may achieve a desired ratio of RS symbols to data symbols. For example, using the scaled numerology, the adaptation component170may change an allocation of RS symbols and data symbols in the time domain.

In block825, the method800may optionally include adapting a second transmission property in the subsequent slot after the transition state according to the defined adaptation schedule. In an aspect, for example, the adaptation component170may adapt the second transmission property in the subsequent slot after the transition state according to the defined adaptation schedule. The adaptation to a second transmission property may be in addition to the adaptation to the numerology, which may be considered a first transmission property. The adaptation of the second transmission property may include reducing a transmission power in the subsequent slot according to a predetermined schedule. The reduction may be applied to a base transmission power. Further details regarding controlling the transmission power in the subsequent slot are described below with respect toFIG. 10. As another example, the adaptation of the second transmission property may include changing an allocation of tones in the frequency domain. In yet another example, the adaptation of the second transmission property may include the adaptation component170changing a symbol waveform mapping such that a different symbol waveform is used to indicate the same data (e.g., ACK or NACK) in the subsequent slot.

In block830, the method800may include transmitting, using the second scaled numerology, a second transmission having a second ratio of reference signal symbols to data symbols, in the subsequent slot, wherein the first ratio is greater than the second ratio. In an aspect, for example, the transmission component175at either the UE110or the base station105may transmit, using the second scaled numerology, the second transmission in the subsequent slot. For example, the transmission component175at the UE110may transmit the second transmission, and the base station105may receive the second transmission according to the second numerology. Conversely, the transmission component175at the base station105may transmit the second transmission, and the UE110may receive the second transmission according to the first numerology. Accordingly, the second transmission may be between the UE110and the base station105in either the uplink direction or the downlink direction. Further, the block830may be performed by the same device (UE110or base station105) that performs the block810. Accordingly, the second transmission may be in the same direction as the first transmission. In an aspect, the transmission component175may use the second numerology and the second ratio selected in block820. The transmission component175may also use any second transmission property selected in block825.

FIG. 9is a flowchart of an example method900of determining whether a UE is operating in a transition state. In an aspect, the method900may be an example of an implementation of the block810inFIG. 8. The method900may be performed using an apparatus (e.g., the UE110or a base station105, for example). Although the method900is described below with respect to the elements of the UE110, other components may be used to implement one or more of the steps described herein.

In block905, the method900may optionally include determining that the UE has transitioned to a connected mode. In an aspect, for example, the detection component165may determine that the UE has transitioned to a connected mode. For example, the detection component165may detect a transition to connected mode performed by a modem of the UE110. In another aspect, a detection component165at a base station105may monitor for signaling from a UE indicating the UE has transitioned to a connected mode. For example, the signaling may include a command from the base station105for the UE110to enter the connected mode or a request from the UE110to transmit data.

In block910, the method900may optionally include determining that the UE has transitioned from a discontinuous reception (DRX) state. In an aspect, for example, the detection component165may determine that the UE has transitioned from the DRX state. For example, the detection component165may determine when the UE transitions from the DRX state based on a DRX cycle of the UE110.

In block915, the method900may optionally include determining that the UE is experiencing changing channel conditions. In an aspect, for example, the detection component165may determine that the UE is experiencing changing channel conditions. For example, the detection component165may analyze a channel quality indicator (CQI) transmitted by the UE110to determine whether the channel conditions are changing. For example, the detection component165may determine whether a change in CQI satisfies a threshold. In another aspect, a detection component165at the base station105may determine whether the channel conditions are changing based on reference signals transmitted by the UE110.

In block920, the method900may optionally include determining that a channel estimation filter is unreliable. In an aspect, for example, the detection component165may determine whether the channel estimation filter180is unreliable. For example, the detection component165may determine that time period since the last update to the channel estimation filter satisfies a threshold.

In block925, the method900may optionally include determining that a threshold number of slots has not occurred since entering the transition state. In an aspect, for example, the detection component165may determine that the threshold number of slots has not occurred since entering the transition state. For example, the detection component165may determine a slot when the UE110enters the transition state. The detection component165may then determine when the UE110leaves the transition state based on the defined adaptation schedule. For example, the adaptation schedule may define a fixed number of slots in the transition state.

In block930, the method900may include determining that the UE is operating in the transition state. In an aspect, for example, the detection component165may determine that the UE is operating in the transition state based on one or more of the blocks805,810,815,820, or825. For example, the detection component165may determine that the UE110is operating in the transition state when at least one of blocks805,810,815,820, or825occurs for a slot.

FIG. 10is a flowchart of an example method1000of adapting a transmission power. In an aspect, the method1000may be an example of an implementation of the block825inFIG. 8. The method1000may be performed using an apparatus (e.g., the UE110). Although the method1000is described below with respect to the elements of the UE110, other components may be used to implement one or more of the steps described herein.

In block1005, the method1000may optionally include receiving a transmission power control command in the transition state. In an aspect, for example, the power component172may receive the transmission power control command while the UE110is in the transition state. The transmission power control command may be transmitted by the base station105.

In block1010, the method1000may optionally include adjusting the transmission power by a first value based on the transmission power control command. In an aspect, for example, the power component172may adjust the transmission power of the UE110by a first value based on the transmission power control command. The first value may be a value for use in the transition state that allows the power component172to quickly adjust the transmission power of the UE110. For example, the first value may be defined by a standard, configured for an individual UE via physical layer signaling (e.g., the PDCCH) or higher layer signaling (e.g., radio resource control), or broadcast by the base station (e.g., in SIBs). The first transmission power may be a multiple of a normal transmission power step size of the UE when operating outside of the transition state.

In block1015, the method1000may optionally include reducing a base transmission power in the subsequent slot according to a predetermined schedule. In an aspect, for example, the power component172may reduce a base transmission power in the subsequent slot according to a predetermined schedule. For example, the power component172may reduce the base transmission power by a fixed amount when leaving the transition state.

In block1020, the method1000may optionally include receiving the same transmission power control command in the subsequent slot. In an aspect, for example, the power component172may receive the same transmission power control command in the subsequent slot. For example, if an UP command is received during the transition state, the same UP command may be received in the subsequent slot. Similarly, if a DOWN command is received during the transition state, the same DOWN command may be received in a subsequent slot. That is, the signaling of transmit power control commands may be the same in the transition state and in the subsequent slot.

In block1025, the method1000may optionally include adjusting the transmission power by a second value based on the same transmission power control command, wherein the first value is greater than the second value. In an aspect, for example, the power component172may adjust the transmission power by the second value based on the same transmission power control command. Because the first value is greater than the second value, the power component172may adjust the transmission power to a lesser extend during the subsequent slot than in the transition state even though the same transmission power command is received. For example, if the transmission power is adjusted by 3 dB during the transition state, the transmission power may be adjusted by 1 dB during the subsequent slot. Applying the smaller second value may allow the power component172to have finer control over the transmission power during the subsequent slots.

FIG. 11schematically illustrates hardware components and subcomponents of the UE110for implementing one or more methods (e.g., methods800,900,1000) described herein in accordance with various aspects of the present disclosure. For example, one example of an implementation of UE110may include a variety of components, some of which have already been described above, but including components such as one or more processors1112and memory1116and transceiver1102in communication via one or more buses1144, which may operate in conjunction with the transition component160to enable one or more of the functions described herein related to including one or more methods of the present disclosure. Further, the one or more processors1112, modem1114, memory1116, transceiver1102, RF front end1188and one or more antennas1165, may be configured to support voice and/or data calls (simultaneously or non-simultaneously) in one or more radio access technologies.

In an aspect, the one or more processors1112can include a modem1114that uses one or more modem processors. The various functions related to transition component160may be included in modem1114and/or processors1112and, in an aspect, can be executed by a single processor, while in other aspects, different ones of the functions may be executed by a combination of two or more different processors. For example, in an aspect, the one or more processors1112may include any one or any combination of a modem processor, or a baseband processor, or a digital signal processor, or a transmit processor, or a receiver processor, or a transceiver processor associated with transceiver1102. In other aspects, some of the features of the one or more processors1112and/or modem1114associated with transition component160may be performed by transceiver1102.

Also, memory1116may be configured to store data used herein and/or local versions of applications or transition component160and/or one or more of its subcomponents being executed by at least one processor1112. Memory1116can include any type of computer-readable medium usable by a computer or at least one processor1112, such as random access memory (RAM), read only memory (ROM), tapes, magnetic discs, optical discs, volatile memory, non-volatile memory, and any combination thereof. In an aspect, for example, memory1116may be a non-transitory computer-readable storage medium that stores one or more computer-executable codes defining transition component160and/or one or more of its subcomponents, and/or data associated therewith, when UE110is operating at least one processor1112to execute UE transition component160and/or one or more of its subcomponents.

Transceiver1102may include at least one receiver1106and at least one transmitter1108. Receiver1106may include hardware, firmware, and/or software code executable by a processor for receiving data, the code comprising instructions and being stored in a memory (e.g., computer-readable medium). Receiver1106may be, for example, a radio frequency (RF) receiver. In an aspect, receiver1106may receive signals transmitted by at least one base station105. Additionally, receiver1106may process such received signals, and also may obtain measurements of the signals, such as, but not limited to, Ec/Io, SNR, RSRP, RSSI, etc. Transmitter1108may include hardware, firmware, and/or software code executable by a processor for transmitting data, the code comprising instructions and being stored in a memory (e.g., computer-readable medium). A suitable example of transmitter1108may including, but is not limited to, an RF transmitter.

Moreover, in an aspect, UE110may include RF front end1188, which may operate in communication with one or more antennas1165and transceiver1102for receiving and transmitting radio transmissions, for example, wireless communications transmitted by at least one base station105or wireless transmissions transmitted by UE110. RF front end1188may be connected to one or more antennas1165and can include one or more low-noise amplifiers (LNAs)1190, one or more switches1192, one or more power amplifiers (PAs)1198, and one or more filters1196for transmitting and receiving RF signals.

In an aspect, LNA1190can amplify a received signal at a desired output level. In an aspect, each LNA1190may have a specified minimum and maximum gain values. In an aspect, RF front end1188may use one or more switches1192to select a particular LNA1190and its specified gain value based on a desired gain value for a particular application.

Further, for example, one or more PA(s)1198may be used by RF front end1188to amplify a signal for an RF output at a desired output power level. In an aspect, each PA1198may have specified minimum and maximum gain values. In an aspect, RF front end1188may use one or more switches1192to select a particular PA1198and its specified gain value based on a desired gain value for a particular application.

Also, for example, one or more filters1196can be used by RF front end1188to filter a received signal to obtain an input RF signal. Similarly, in an aspect, for example, a respective filter1196can be used to filter an output from a respective PA1198to produce an output signal for transmission. In an aspect, each filter1196can be connected to a specific LNA1190and/or PA1198. In an aspect, RF front end1188can use one or more switches1192to select a transmit or receive path using a specified filter1196, LNA1190, and/or PA1198, based on a configuration as specified by transceiver1102and/or processor1112. In an aspect, during subsequent slots after the transition state, the channel estimation filter180may be used as one of the filters1196or may be used to determine which of the filters1196is selected.

As such, transceiver1102may be configured to transmit and receive wireless signals through one or more antennas1165via RF front end1188. In an aspect, transceiver may be tuned to operate at specified frequencies such that UE110can communicate with, for example, one or more base stations105or one or more cells associated with one or more base stations105. In an aspect, for example, modem1114can configure transceiver1102to operate at a specified frequency and power level based on the UE configuration of the UE110and the communication protocol used by modem1114.

In an aspect, modem1114can be a multiband-multimode modem, which can process digital data and communicate with transceiver1102such that the digital data is sent and received using transceiver1102. In an aspect, modem1114can be multiband and be configured to support multiple frequency bands for a specific communications protocol. In an aspect, modem1114can be multimode and be configured to support multiple operating networks and communications protocols. In an aspect, modem1114can control one or more components of UE110(e.g., RF front end1188, transceiver1102) to enable transmission and/or reception of signals from the network based on a specified modem configuration. In an aspect, the modem configuration can be based on the mode of the modem and the frequency band in use. In another aspect, the modem configuration can be based on UE configuration information associated with UE110as provided by the network during cell selection and/or cell reselection.

AlthoughFIG. 11illustrates hardware components and subcomponents of the UE110, the base station105may include similar components for implementing one or more methods (e.g., methods800,900,1000) described herein in accordance with various aspects of the present disclosure.