Licensed assisted access signal detection for reducing power use

This disclosure relates to techniques for detecting a signal and powering off at least some receiver components if no signal is detected. A wireless device may take one or more measurements of one or more signals. The wireless device may determine, based on the measurements, whether a signal (e.g., a signal of a licensed assisted access cell) is anticipated during an upcoming time period, e.g., a subframe or portion of a subframe. If no signal is anticipated, the wireless device may power off at least some receiver functions.

TECHNICAL FIELD

The present application relates to wireless communication, including methods, systems, and apparatuses to reduce power consumption.

DESCRIPTION OF THE RELATED ART

Wireless communication systems are rapidly growing in usage. Further, wireless communication technology has evolved from voice-only communications to also include the transmission of data, such as Internet and multimedia content.

Mobile electronic devices may take the form of smart phones or tablets that a user typically carries. Wearable devices (also referred to as accessory devices) are a newer form of mobile electronic device, one example being smart watches. Additionally, low-cost low-complexity wireless devices intended for stationary or nomadic deployment are also proliferating as part of the developing “Internet of Things”. In other words, there is an increasingly wide range of desired device complexities, capabilities, traffic patterns, and other characteristics. In general, it would be desirable to recognize and provide improved support for a broad range of desired wireless communication characteristics. For example, the design of cellular networks may increasingly include licensed assisted access (LAA). LAA cells may not transmit in all subframes, however mobile electronic devices may use power to detect transmissions. Therefore, improvements in the field are desired.

SUMMARY

Embodiments are presented herein of, inter alia, systems, apparatuses, and methods for performing cell set based mobility as part of wireless communications.

As noted above, the number of use cases wireless devices is growing, including use of licensed assisted access (LAA) cells. LAA cells may not transmit any signal during some time periods, however legacy devices may continue to receive during such time periods. This disclosure presents techniques for a wireless device to reduce power consumption based on signal detection. A wireless device may detect whether a signal is expected so that the wireless device may shut off radio components during time periods when no signal is expected. Thus, the wireless device may reduce power use by reducing the amount of time that radio components are active.

The techniques described herein may be implemented in and/or used with a number of different types of devices, including but not limited to cellular phones, tablet computers, accessory and/or wearable computing devices, portable media players, cellular base stations and other cellular network infrastructure equipment, servers, and any of various other computing devices.

DETAILED DESCRIPTION

Acronyms

The following acronyms are used in the present disclosure.

3GPP: Third Generation Partnership Project

3GPP2: Third Generation Partnership Project 2

RAN: Radio Access Network

GSM: Global System for Mobile Communications

UMTS: Universal Mobile Telecommunications System

UTRAN: UMTS Terrestrial Radio Access Network or Universal Terrestrial Radio Access Network

UE: User Equipment

LTE: Long Term Evolution

NR: New Radio

E-UTRAN: Evolved UMTS Radio Access Network or Evolved Universal Radio Access Network

RRC: Radio Resource Control

RLC: Radio Link Control

MAC: Media Access Control

PDCP: Packet Data Convergence Protocol

RF: radio frequency

BS: base station

MME: Mobility Management Entity

RAT: radio access technology

PLMN: public land mobile network

LAA: licensed assisted access

DRS: discovery reference signal

DMTC: DRS measurement timing configuration

CRS: cell reference signal

PSS: primary sounding signal

SSS: secondary sounding signal

IRX: internal receiver

ORX: out receiver

PDCCH: physical downlink control channel

PDSCH: physical downlink shared channel

PRB: physical resource block

DCI: downlink control information

RSRP: reference signal received power

Terms

FIG. 1illustrates an exemplary (and simplified) wireless communication system in which aspects of this disclosure may be implemented, according to some embodiments. For example, any or all of the wireless devices illustrated inFIG. 1may be configured for performing signal detection as described herein, e.g., according to one or more of the methods described herein. It is noted that the system ofFIG. 1is merely one example of a possible system, and embodiments may be implemented in any of various systems, as desired.

The base station102A may be a base transceiver station (BTS) or cell site, and may include hardware and/or software that enables wireless communication with the UEs106A through106N. The base station102A may also be equipped to communicate with a network100(e.g., a core network of a cellular service provider, a telecommunication network such as a public switched telephone network (PSTN), and/or the Internet, among various possibilities). Thus, the base station102A may facilitate communication among the user devices and/or between the user devices and the network100.

The communication area (or coverage area) of the base station may be referred to as a “cell.” The base station102A and the UEs106may be configured to communicate over the transmission medium using any of various radio access technologies (RATs), also referred to as wireless communication technologies, or telecommunication standards, such as GSM, UMTS (WCDMA, TD-SCDMA), LTE, LTE-Advanced (LTE-A), NR, 3GPP2 CDMA2000 (e.g., 1×RTT, 1×EV-DO, HRPD, eHRPD), Wi-Fi, WiMAX etc.

Note that a UE106may be capable of communicating using multiple wireless communication standards. For example, a UE106might be configured to communicate using two or more of GSM, UMTS, CDMA2000, WiMAX, LTE, LTE-A, NR, WLAN, Bluetooth, one or more global navigational satellite systems (GNSS, e.g., GPS or GLONASS), one and/or more mobile television broadcasting standards (e.g., ATSC-M/H or DVB-H), etc. Other combinations of wireless communication standards (including more than two wireless communication standards) are also possible.

FIG. 2illustrates user equipment106(e.g., one of the devices106A through106N) in communication with a base station102(e.g., one of the base stations102A through102N), according to some embodiments. The UE106may be a device with cellular communication capability such as a mobile phone, a hand-held device, a wearable device, a computer or a tablet, or virtually any type of wireless device.

As noted above, the UE106may be configured to communicate using any of multiple RATs. For example, the UE106may be configured to communicate using two or more of GSM, CDMA2000, UMTS, LTE, LTE-A, NR, WLAN, or GNSS. Other combinations of wireless communication technologies are also possible.

FIG. 3—Block Diagram of a UE Device

FIG. 3illustrates one possible block diagram of a UE device106. As shown, the UE device106may include a system on chip (SOC)300, which may include portions for various purposes. For example, as shown, the SOC300may include processor(s)302which may execute program instructions for the UE device106, and display circuitry304which may perform graphics processing and provide display signals to the display360. The SOC300may also include motion sensing circuitry370which may detect motion of the UE106, for example using a gyroscope, accelerometer, and/or any of various other motion sensing components. The processor(s)302may also be coupled to memory management unit (MMU)340, which may be configured to receive addresses from the processor(s)302and translate those addresses to locations in memory (e.g., memory306, read only memory (ROM)350, flash memory310). The MMU340may be configured to perform memory protection and page table translation or set up. In some embodiments, the MMU340may be included as a portion of the processor(s)302.

As shown, the SOC300may be coupled to various other circuits of the UE106. For example, the UE106may include various types of memory (e.g., including NAND flash310), a connector interface320(e.g., for coupling to a computer system, dock, charging station, etc.), the display360, and wireless communication circuitry330(e.g., for LTE, LTE-A, NR, CDMA2000, Bluetooth, Wi-Fi, NFC, GPS, etc.).

The UE device106may include at least one antenna, and in some embodiments multiple antennas335aand335b(and/or further additional antennas), for performing wireless communication with base stations and/or other devices. For example, the UE device106may use antennas335aand335bto perform the wireless communication. As noted above, the UE device106may in some embodiments be configured to communicate wirelessly using a plurality of wireless communication standards or radio access technologies (RATs).

The wireless communication circuitry330may include Wi-Fi Logic332, a Cellular Modem334, and Bluetooth Logic336. The Wi-Fi Logic332is for enabling the UE device106to perform Wi-Fi communications on an 802.11 network. The Bluetooth Logic336is for enabling the UE device106to perform Bluetooth communications. The cellular modem334may be a lower power cellular modem capable of performing cellular communication according to one or more cellular communication technologies (e.g., LTE, 5G NR, GSM, etc.).

As described herein, UE106may include hardware and software components for implementing embodiments of this disclosure. For example, one or more components of the wireless communication circuitry330(e.g., cellular modem334) of the UE device106may be configured to implement part or all of the methods described herein, e.g., by a processor executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium), a processor configured as an FPGA (Field Programmable Gate Array), and/or using dedicated hardware components, which may include an ASIC (Application Specific Integrated Circuit).

FIG. 4—Block Diagram of a Base Station (BS)

The base station102may include at least one antenna434, and possibly multiple antennas. The antenna(s)434may be configured to operate as a wireless transceiver and may be further configured to communicate with UE devices106via radio430(or multiple radios430). The antenna(s)434communicates with the radio430via communication chain432. Communication chain432may be a receive chain, a transmit chain or both. The radio430may be configured to communicate via various wireless communication standards, including, but not limited to, LTE, LTE-A, NR, GSM, UMTS, CDMA2000, Wi-Fi, etc.

The base station102may be configured to communicate wirelessly using multiple wireless communication standards. In some instances, the base station102may include multiple radios, which may enable the base station102to communicate according to multiple wireless communication technologies. For example, as one possibility, the base station102may include an LTE radio for performing communication according to LTE as well as a Wi-Fi radio for performing communication according to Wi-Fi. In such a case, the base station102may be capable of operating as both an LTE base station and a Wi-Fi access point. As another possibility, the base station102may include a multi-mode radio which is capable of performing communications according to any of multiple wireless communication technologies (e.g., LTE and Wi-Fi, LTE and UMTS, LTE and CDMA2000, LTE and 5G NR, UMTS and GSM, etc.). The BS102may provide one or more cells of one or more communication technologies and/or one or more public land mobile networks (PLMNs). The BS102may provide multiple cells which may be organized, grouped, or configured as one or more cell sets, according to some embodiments. One or more cell sets that are provided by BS102may also include cells provided by one or more additional base stations, according to some embodiments.

The BS102may be an eNodeB (eNB) or gNodeB (gNB), according to some embodiments.

5G New Radio (NR) and LTE may increasingly include a variety of cell types, e.g., including licensed and/or unlicensed spectrum. For example, licensed assisted access (LAA) cells may be increasingly common. Note that an LAA cell may aggregate licensed and unlicensed spectrum of a radio access network, e.g., at a media access control level, among various possibilities. For example, an LAA cell (e.g., a special type of secondary cell or SCell) may operate in an unlicensed band and may be assisted by an LTE cell (e.g., a primary cell or PCell) that may operate in a licensed band.

Unlike legacy LTE cells (e.g., operating in licensed spectrum) which may consistently transmit reference signals (e.g., cell-specific reference signals (CRS), PSS, SSS, etc.) in each subframe (e.g., regardless of whether the LTE cell has data to transmit), an LAA cell may not transmit reference signals under some circumstances. For example, outside of a discovery reference signal (DRS) measurement timing configuration (DMTC) window, a LAA cell may choose not to transmit any signal when LAA cell has no data to transmit. In a subframe during which an LAA cell transmits data (e.g., LTE data) on unlicensed frequency, reference signals may also be transmitted on unlicensed frequency (e.g., as in LTE cells in licensed frequency bands). An LAA cell may seek to avoid unnecessary conflicts with other uses of unlicensed frequency (e.g., Wi-Fi, Bluetooth, etc.).

A discovery window, such as a DMTC window may be configured as desired (e.g., configuration may be carrier-specific). For example, a DMTC window may be a 6 ms window during which all cells on a given carrier are configured to transmit DRS. During a subframe that collides with a discovery window, the LAA cell may transmit reference signals, e.g., DRS, on unlicensed spectrum. DRS may be similar to CRS and may be transmitted in time/frequency resources associated with discovery (e.g., as configured by the network for the DMTC window). Thus, during a discovery window, a UE may demodulate reference signals. For example, a UE may demodulate DRS/CRS which may be scrambled by subframe0(e.g., for regular subframe locations0-4) or subframe5(e.g., for regular subframe locations5-9) in order to accommodate possible DRS/CRS subframe shift.

In some embodiments, a UE may keep its receiver functions/components (e.g., Rx) powered on during an LAA signal detection period. A UE may actively track potential signal (e.g., grants) from an LAA cell. During this period, the UE may try to demodulate and decode PDCCH, according to some embodiments. This behavior may result in power use for Rx (e.g., for demodulation and/or decoding) when no LAA signal is present. Accordingly, it may be advantageous to determine whether an LAA signal is present and to power off at least some Rx components/functions when no LAA signal is anticipated (e.g., an empty subframe). For example, such techniques may allow for Rx to be shut off at symbol5-7in subframes when the UE detects an empty subframe (e.g., with sufficiently high confidence).

FIG. 5is a flow chart diagram illustrating a method for detecting signals and powering off at least some Rx functions, according to some embodiments. The method ofFIG. 5may provide power savings, e.g., reducing the amount of time that Rx functions are active and avoiding receiving when no signal (e.g., LAA) may be present, according to some embodiments. For example, the method ofFIG. 5may enable the UE to minimize power use to receive during subframes in which no signal may be detected.

In various embodiments, some of the elements of the method shown may be performed concurrently, in a different order than shown, may be substituted for by other method elements, or may be omitted. Additional method elements may also be performed as desired.

Aspects of the method ofFIG. 5may be implemented by a wireless device, such as the UEs106A-B and/or BS102illustrated in and described with respect toFIGS. 1-4, or more generally in conjunction with any of the computer systems or devices shown in the Figures, among other devices, as desired. Note that while at least some elements of the method ofFIG. 5are described in a manner relating to the use of communication techniques and/or features associated with 3GPP specification documents, such description is not intended to be limiting to the disclosure, and aspects of the method ofFIG. 5may be used in any suitable wireless communication system, as desired. For example, although aspects of the method ofFIG. 5are described relating to LAA cells, it should be noted that the method may apply to other types of cells or wireless networks and other types of aggregation. As shown, the method may operate as follows.

A wireless device (e.g., UE106) may perform measurements of one or more signals transmitted by one or more base stations (e.g., BS102) (510). The UE and the BS may communicate using one or more radio access technologies, e.g., NR. The UE and BS may exchange application and/or control data in the uplink and/or downlink directions. The communication and measurements may occur on any frequency or combination of frequencies, e.g., including licensed and/or unlicensed spectrum. The communication and measurements may continue (e.g., periodically, randomly, as needed, etc.) for any amount of time. For example, the communication and measurements may occur over any number of subframes and/or symbols. The measurements may include any radio link measurements such as signal-noise ratio (SNR), signal to interference and noise ratio (SINR), reference signal received power (RSRP), reference signal received quality (RSRQ), received signal strength indicator (RSSI), channel quality indicator (CQI), channel state information (CSI), etc. The UE and/or BS may retain a history of measurement values. The UE/BS may compare the measurement values, or metrics calculated based on the measured values, to one or more thresholds. The UE/BS may use various parameters, e.g., for hysteresis, in such comparisons. The measurements, thresholds, and/or parameters may be configured by the BS (e.g., by the network) and/or by the UE. The UE and/or BS may report measurement values, comparison results, etc. to each other and/or to the network at any time.

In some embodiments, the UE may measure and record SNR and RSRP of an LAA cell over any number of time intervals (e.g., subframes); these measurements may be referred to as baseline measurements. The SNR and RSRP of the LAA cell in previous non-empty time intervals may be useful to the UE for determining whether/when to turn of Rx features in a current time interval. For example, the UE may calculate averages (e.g., moving averages, possibly weighted based on time) of SNR and RSRP over a number of subframes. The number of subframes may be limited to a number of most recent non-empty subframes; empty subframes may be excluded. The UE may use any of various other statistics instead of or in addition to averaging, e.g., the UE may calculate median or other percentile, standard deviation, variance, range, etc. Such measurements and statistics may establish a baseline for the signal characteristics of a cell when transmissions occur, e.g., during non-empty time intervals. Note that other measurements may be used in addition to or instead of SNR and/or RSRP, e.g., SINR and/or RSRQ may be used, among various possibilities. In some embodiments, only a single measurement (e.g., only SNR or only RSRP) may be used. The RSRP may be measured and recorded for CRS, DRS, and/or any other reference signals.

In some embodiments, the UE may measure RSRP of a current time interval, e.g., subframe. These measurements may be referred to as current interval measurements. For example, the UE may measure the RSRP of the CRS and/or DRS (or any other reference signals, e.g., PSS, SSS). Such reference signals may be scheduled relatively early in the time interval, such as in symbol0of a subframe, among various possibilities. Thus, by determining that a reference signal is not (or is) present, the UE may be able to infer that the time interval is (or is not) empty and may (or may not) be able to power off Rx functions.

In some embodiments, the UE may measure the RSRP of CRS as current interval measurements. CRS may be present during any time interval that the cell transmits data. To measure CRS (e.g., to detect an LTE signal), the UE may assume that CRS is scrambled using information from the current time interval (e.g., a current subframe number/information). For example, CRS may be scheduled (e.g., if data is to be transmitted) during symbol0of a subframe.

In some embodiments, the UE may also measure DRS as current interval measurements, e.g., within a discovery window. To measure DRS (e.g., within a DMTC window), the UE may assume that CRS is scrambled by subframe0(e.g., for subframes n=0-4) or by subframe5(e.g., for subframes n=5-9). The UE may assume another scrambling subframe/symbol/time, e.g., according to an RS shift of the cell.

The RSRP (e.g., of CRS and/or of DRS) may be used by the UE to determine whether the current time interval is empty, e.g., to determine whether LAA signal is anticipated during the remainder of the subframe. Note that other measurements may be used in addition to or instead of RSRP, e.g., RSRQ may be used, among various possibilities. The measurements may be taken for any port or ports containing reference signals.

The baseline and/or current interval measurements may be taken over the entire bandwidth used for transmissions from the cell (e.g., BS) to the UE. Any number of physical resource blocks (PRBs), subcarriers, channels, subchannels, etc., may be included.

The wireless device (e.g., UE106) may apply decision metrics to determine whether or not a current time interval is empty, e.g., to determine if a signal is anticipated in the remainder of the time interval (520). The decision metrics (e.g., detection metrics) may use any measurement or combination of measurements and may compare the measurements to one or more thresholds. For example, the decision metrics may use the RSRP of the current time interval and the baseline RSRP and/or SNR of one or more recent (e.g., non-empty) time intervals.

A first decision metric may be calculated based on the RSRP (e.g., and/or other measurements, as described above) of the current time interval (current interval measurements). The first decision metric may be calculated separately for CRS and DRS (e.g., DRS may be used if the current time interval collides with or overlaps with a discovery window). In some embodiments, a combined first decision metric (e.g., based on both CRS and DRS) may be calculated.FIGS. 7, 8, and 10, described below, provide more detail on the calculation of such a first decision metric.

This first decision metric may be compared to a first threshold (e.g., a threshold value that indicates the time interval is empty or “empty threshold”). If the value of the first decision metric is below the empty threshold, the UE may determine that the current time interval is empty, e.g., that no LAA signal is anticipated during the current subframe. The first decision metric being below the empty threshold may indicate that the signal energy (e.g., of the reference signal, e.g., CRS or DRS) is low. In other words, the UE may not detect an RS, e.g., in symbol0of the current subframe.

In some embodiments, if the first decision metric is above the first/empty threshold, this first decision metric may also be compared to a second threshold (e.g., a threshold that indicates that the time interval includes data via LTE, NR, etc. or a “data threshold”). If the value of the first decision metric is above the second/data threshold, the UE may determine that the current time interval is not empty, e.g., that an LAA signal is anticipated during the current subframe. If the first decision metric is between the first and second thresholds, the decision metric may be considered to be in an uncertainty region. In other words, the current time interval may be empty, however the measurements may not provide sufficient confidence. Accordingly, the UE may treat the uncertainty region similarly to the region above the second threshold, e.g., the UE may act as if the current interval is not empty and may continue to keep Rx functions/circuitry active, according to some embodiments. Thus, the UE may seek to avoid false positives (e.g., wrongly determining an empty time interval) by using the second threshold.

Respective second and third decision metrics may be calculated based on baseline measurements of SNR and RSRP of recent (e.g., non-empty) time intervals. Note that alternative or additional measurements may also be used, as described above. In some embodiments, the baseline measurements may be based on a fixed or variable number of previous time intervals, excluding the current time interval. For example, in a current subframe number101, the recent time intervals may include subframes50-100or0-100, among various possibilities. Thus, the baseline measurements may be based on all of the non-empty subframes in the such a range.

The UE may compare the baseline measurements of SNR and RSRP to respective weak signal thresholds. If the measurements (e.g., RSRP and/or SNR of recent, non-empty time intervals) is below respective RSRP and/or SNR weak signal thresholds, the UE may determine that the first decision metric may not be able to accurately determine whether the time interval is empty. In other words, if recent measurements (e.g., of the same cell) suggest that the signal is too weak (e.g., and/or too much interference/noise is present), the first decision metric may be low (e.g., below the empty threshold) simply because of weak signal or high noise levels. Therefore, the UE may seek to avoid false positives (e.g., wrongly determining an empty time interval) by treating the time interval as non-empty (e.g., even if the first decision metric is below the first/empty threshold).

In some embodiments, the UE may adjust the thresholds for the decision metrics over time and/or based on other information. In other words, the UE may retain data on the levels of the decision metrics and whether a time interval is empty. Based on such retained data, the UE may calibrate the thresholds over time. For example, a UE may use such retained data to narrow the uncertainty region, e.g., to more precisely determine the values that indicate a non-empty vs. empty time interval. Thus, the UE may adjust the first and second thresholds for use in future time intervals. Further, such retained data may include and consider other factors, such as motion/orientation of the UE, location of the UE, cell identification, network identity, time of day, day of week, etc. For example, the UE may consider past history with a certain cell (or location) in evaluating the second decision metric. In other words, the UE may consider past determinations of empty/non-empty frames for a specific LAA cell and may adjust the weak signal threshold and/or the first/second thresholds of the first decision metric based on that history. Thus, in some embodiments, the described thresholds may be automatically or dynamically adjusted. Further, the UE may set or adjust the first/empty and second/data thresholds based on the baseline measurements. In other words, in some embodiments, the UE may use the baseline measurements to set thresholds for use in comparing the current time interval measurements (e.g., via first decision metrics) and may thus not perform a comparison of the baseline measurements to weak signal thresholds.

The wireless device (e.g., UE106) may determine to power off some or all Rx functions, components, and/or circuitry based at least in part on the decision metrics (530). The UE may consider the first, second, and third decision metrics (and/or additional/alternative metrics) together. The UE may further consider trigger conditions specific to the time interval. For example, the UE may consider the first decision metric in terms of CRS if the current time interval does not collide with a discovery window. However, if the current time interval does collide with (e.g., overlap with or coincide with) a discovery window, the UE may consider the first decision metric both in terms of CRS and DRS. In other words, if the current time interval is outside of a discovery window, the UE may not anticipate DRS and may only measure CRS. Thus, the UE may only calculate the first decision metric based on CRS. If the current time interval collides with a discovery window, the UE may anticipate both CRS and DRS, may measure both CRS and DRS, and may compare the first decision metric based on CRS and the first decision metric based on DRS to the empty threshold. In some embodiments, the empty threshold applied to CRS may be the same as the empty threshold applied to DRS. In other embodiments, different empty thresholds for CRS and DRS may be applied.

In some embodiments, the trigger condition to turn off Rx may be summarized as follows. In a time interval that does not collide with a discovery interval, Rx may be turned off early if: 1) first decision metrics for CRS of a current interval are below the first (e.g., empty) threshold and 2) the second and/or third decision metrics of recent time intervals (e.g., baseline measurements) exceed respective weak signal thresholds. If either of these trigger conditions is not met, the UE may determine that the time interval is not empty (e.g., or there is not sufficient confidence that the interval is empty) and may thus determine to leave Rx powered on. In a time interval that does collide with a discovery interval, Rx may be turned off early if: 1) first decision metrics for CRS of a current interval are below the first (e.g., empty) threshold, 2) the second and/or third decision metrics of recent time intervals (e.g., baseline measurements) exceed respective weak signal thresholds, and 3) first decision metrics for DRS are below the first (e.g., empty) threshold. Again, if any of these conditions is not met, the UE may leave Rx powered on. It should be noted that other trigger conditions or combinations may be used. For example, either the second or the third decision metrics exceeding the respective weak signal thresholds may be sufficient (e.g., in combination with the first decision metrics for CRS and/or DRS below the first threshold).

In some embodiments, some of the trigger conditions summarized above may be omitted. For example, the comparison of baseline measurements and weak signal thresholds may not be used as a separate trigger condition, according to some embodiments. Instead, the baseline measurements may be used to set/adjust the first/empty threshold. Thus, comparison of the current time interval measurements (of CRS and/or DRS) to the first empty threshold(s) may be the only comparison performed and may be the only trigger condition.

In some embodiments, the UE may power off the Rx based at least in part on other information. For example, the UE may consider scheduling information received from the network such as a downlink grant (e.g., PDSCH) received in a current and/or a previous time interval (e.g., over PDCCH). Similarly, the UE may consider any indication from a network that LAA signals would or would not be transmitted during the current time interval.

In some embodiments, in response to determining that the current time interval is empty, the UE may power off any or all Rx functions, components or circuitry. For example, the UE may power off any or all of receiver chains, one or more antennas, one or more radios, baseband circuitry, radio frequency circuitry, one or more controllers, one or more processors, etc. The UE may power of Rx functions, components, or circuitry for use with one or more frequency ranges (e.g., unlicensed spectrum). The UE may power off Rx as soon as possible following the determination in order to achieve the greatest energy saving benefit. The timing of powering off Rx may vary based on whether a downlink grant was detected in a previous time interval, whether the current interval collides with a discovery window, and/or other factors. The UE may power off Rx for the remainder of the current time interval. It should be noted that the Rx may be powered back on for a subsequent time interval. In some embodiments, the Rx may remain powered off for one or more subsequent time intervals.

The method ofFIG. 5may be applied to any number of time intervals. The UE may determine that some intervals are empty and therefore turn of Rx for these intervals. For other intervals, the UE may determine that there is not sufficient confidence that they are empty (e.g., that they are not empty) and may leave Rx on for these other intervals.

FIGS. 6-10and the following additional information are provided as being illustrative of further considerations and possible implementation details relating to the method ofFIG. 5and are not intended to be limiting to the disclosure as a whole. Numerous variations and alternatives to the details provided herein below are possible and should be considered within the scope of the disclosure.

FIG. 6illustrates various levels of the first decision metrics. As shown, below the first (e.g., empty) threshold may be considered a low signal region based on a low value of the first decision metrics. For example, RSRP of CRS or DRS may be low. Below the first threshold, a wireless device may determine that a current time interval is empty. Accordingly, in this region, the wireless device may power off Rx and may not demodulate or decode for the remainder of the time interval in order to save energy. For example, the UE may not decode downlink control information (DCI). It should be appreciated that the UE may consider additional factors in determining that the time interval is empty and powering of Rx. For example, the UE may not power off Rx if the second or third decision metrics are below a weak signal threshold.

Above the second (e.g., LTE) threshold, the first decision metrics may be high. In other words, the UE may detect that the time interval is not empty. For example, an LTE or NR subframe may be detected. Thus, the UE may not power off Rx and may continue to decode and demodulate signals such as DCI.

Between the first and second thresholds may be considered an uncertainty region. In this region, the first decision metric may be too high for the UE to determine an empty time interval with confidence. Accordingly, in order to avoid a false positive (e.g., turning of Rx and failing to receive during a non-empty subframe, thus missing signals transmitted to the UE), the UE may not power off Rx and may continue to decode and demodulate signals such as DCI. In other words, in this region the UE may prioritize performance (e.g., timely reception) over power savings.

In some embodiments, the first and second thresholds may be configured as desired and may further be adjusted over time.

FIG. 7illustrates one possible mathematical approach for calculating first decision metrics. As shown, Xm(6k+i) may indicate the RSRP (or other measurement) of descrambled a reference signal (e.g., CRS) at symbol0(or other symbol, as desired) transmitted from Tx port m at a carrier index6k+i. The RS shift for the cell may be represented as i. Nprbmay refer to the number of physical resource blocks in the bandwidth. Thus, the first term may represent a scalar product with a 6 carrier shift, and the second term may represent a scalar product with a 12 carrier shift. The numerators and denominators of each of these scalar product terms may be summed over the bandwidth (e.g., based on the carrier index, k ranging over the number of PRBs, e.g., 0 to 2Nprb−2 for the first term, and 0 to 2Nprb−3 for the second term). The numerator of the first term may calculate the conjugate of adjacent (e.g., 6 subcarriers apart) and the numerator of the second term may calculate the conjugate of once removed (e.g., 12 subcarriers apart) reference signals. The sum of the scalar product terms may be summed over the number of ports m used for reference signals (e.g.,0and1in the illustrated example). It should be noted that the calculation illustrated inFIG. 7is exemplary only and that other formulations are possible. For example, different numbers of scalar product terms (e.g., one term for calculating adjacent instances, or more terms for calculating further separated conjugates), different numbers of ports, different subcarrier spacings of reference signals, etc., may be used.

FIG. 8is a diagram of a physical resource block illustrating the operation of the calculation ofFIG. 7in the case of 2 CRS ports in a subframe. The exemplary bandwidth may include 100 physical resource blocks (e.g., Nprb=100). As shown, the subframe may include 14 symbols (left to right) and 12 subcarriers (top to bottom). The calculation may be based on CRS detected during symbol0(810) on ports0and1. The first scalar product term calculates conjugates of all adjacent instances (e.g., spacing of 6) of CRS on the port. As shown, this term may calculate conjugates for k=0 (subcarrier1) and k=1 (subcarrier7), k=1 (subcarrier7) and k=2 (subcarrier13), etc. The second iteration (e.g., scalar product term) calculates conjugates for alternating instances (e.g., spacing of12) of CRS on the port, e.g., for k=0 (subcarrier1) and k=1 (subcarrier13), etc. As illustrated, k may range from 0 to 199 (e.g., 2*Nprb−2=199). It should be noted the illustrated arrangement is exemplary only. Other subcarrier spacing, number of ports, number of PRBs, symbols, etc. may be used.

FIG. 9is a table summarizing four exemplary use cases illustrating the operation of the method ofFIG. 5including the timing of powering off Rx as described below.

In a first use case (scenario 1), for example, the current time interval is inside a DMTC window and a downlink (DL) grant was found in the last (e.g., prior) subframe (SF). The UE may attempt to detect DRS after an empty subframe has been preliminarily determined based on CRS. In other words, the UE may attempt to demodulate CRS (e.g., of symbol0) and measure the RSRP of CRS and may calculate first decision metrics based on CRS. Based on the first decision metrics using CRS in combination with second and third decision metrics (e.g., calculated based on previous subframes), the UE may determine that CRS is not found. After measuring the CRS, the UE may perform various tasks related to the downlink grant from the previous subframe. The UE may also attempt to demodulate DRS (e.g., also of symbol0), measure RSRP of DRS and may calculate first decision metrics based on DRS. Based on the first decision metrics using DRS in combination with second and third decision metrics (e.g., calculated based on previous subframes), the UE may determine that DRS is not found. Thus, the UE may determine that the subframe is empty. In some embodiments, the UE may power off Rx at symbol7and may thus have Rx off for the remaining 7 symbols of the SF, however it should be noted that other timing is possible. This scenario may be viewed as a worst case, e.g., resulting in less power savings than the other illustrated scenarios.

In a second use case (scenario 2), for example, the current time interval is inside a DMTC window and no DL grant was found in the last subframe. The UE may attempt to detect DRS after an empty subframe has been preliminarily determined based on CRS. In other words, the UE may attempt to demodulate CRS (e.g., of symbol0) and measure the RSRP of CRS and may calculate first decision metrics based on CRS. Based on the first decision metrics using CRS in combination with second and third decision metrics (e.g., calculated based on previous subframes), the UE may determine that CRS is not found. As no DL grant is present, no related tasks may be performed. The UE may also attempt to demodulate DRS (e.g., also of symbol0), measure RSRP of DRS and may calculate first decision metrics based on DRS. Based on the first decision metrics using DRS in combination with second and third decision metrics (e.g., calculated based on previous subframes), the UE may determine that DRS is not found. Thus, the UE may determine that the subframe is empty. In some embodiments, the UE may power off Rx at symbol6and may thus have Rx off for the remaining 8 symbols of the SF, however it should be noted that other timing is possible.

In a third use case (scenario 3), for example, the current time interval is not inside a DMTC window and a downlink grant was found in the last subframe. The UE may not attempt to detect DRS after CRS. In other words, the UE may attempt to demodulate CRS (e.g., of symbol0) and measure the RSRP of CRS and may calculate first decision metrics based on CRS. Based on the first decision metrics using CRS in combination with second and third decision metrics (e.g., calculated based on previous subframes), the UE may determine that CRS is not found. After measuring the CRS, the UE may perform various tasks related to the downlink grant from the previous subframe. Thus, the UE may determine that the subframe is empty. In some embodiments, the UE may power off Rx at symbol6and may thus have Rx off for the remaining 8 symbols of the SF, however it should be noted that other timing is possible.

In a fourth use case (scenario 4), for example, the current time interval is not inside a DMTC window and no downlink grant was found in the last subframe. The UE may not attempt to detect DRS after CRS. In other words, the UE may attempt to demodulate CRS (e.g., of symbol0) and measure the RSRP of CRS and may calculate first decision metrics based on CRS. Based on the first decision metrics using CRS in combination with second and third decision metrics (e.g., calculated based on previous subframes), the UE may determine that CRS is not found. Thus, the UE may determine that the subframe is empty. In some embodiments, the UE may power off Rx at symbol5and may thus have Rx off for the remaining 9 symbols of the SF, however it should be noted that other timing is possible. This may be considered a best case scenario, e.g., resulting in high power savings.

FIG. 10illustrates another possible mathematical approach for calculating first decision metrics, e.g., similar toFIG. 7. This illustrated formulation may use a single term to calculate conjugates of adjacent instances of reference signals.

In some embodiments, a network device (e.g., a BS102) may be configured to include a processor (or a set of processors) and a memory medium, where the memory medium stores program instructions, where the processor is configured to read and execute the program instructions from the memory medium, where the program instructions are executable to implement any of the various method embodiments described herein (or, any combination of the method embodiments described herein, or, any subset of any of the method embodiments described herein, or, any combination of such subsets). The network device may be realized in any of various forms.

As described above, aspects of the present technology may include the gathering and use of data available from various sources, e.g., to improve or enhance functionality. The present disclosure contemplates that in some instances, this gathered data may include personal information data that uniquely identifies or can be used to contact or locate a specific person. Such personal information data can include demographic data, location-based data, telephone numbers, email addresses, Twitter ID's, home addresses, data or records relating to a user's health or level of fitness (e.g., vital signs measurements, medication information, exercise information), date of birth, or any other identifying or personal information. The present disclosure recognizes that the use of such personal information data, in the present technology, may be used to the benefit of users.