Patent Description:
Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (for example, bandwidth, transmit power, or the like, or a combination thereof).

The above multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different user equipments (UEs) to communicate on a municipal, national, regional, and even global level. New Radio (NR), which may also be referred to as <NUM>, is a set of enhancements to the LTE mobile standard promulgated by the 3GPP. NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) (CP-OFDM) on the downlink (DL), using CP-OFDM or SC-FDM (for example, also known as discrete Fourier transform spread OFDM (DFT-s-OFDM)) on the uplink (UL), as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. Preferably, these improvements are applicable to other multiple access technologies and the telecommunication standards that employ these technologies.

A cellular broadcast service may be used to allow one or more base stations to broadcast communications for receipt by any UEs in a geographical area (for example, one or more cells) covered by the broadcast (such that any UE located in the one or more cells can receive the broadcasted communications). An example of a cellular broadcast service is a television service. In order to extend and enhance outreach and capabilities of cellular broadcast services (beyond the outreach and capabilities of cellular broadcast services in a legacy network, such as an LTE network), additional scenarios should be considered. In order to support a cellular broadcast service in these additional scenarios, a design of new numerologies is needed (for example, in terms of OFDM subcarrier spacing, cyclic-prefix length, reference signal design, or the like). However, a challenge in such scenarios is to ensure that cell acquisition information - which informs a UE of details of the cellular broadcast scheme employed in the network-is received reliably by UEs. Ensuring receipt of cell acquisition information is challenging because, to be backward compatible with legacy UEs (for example, LTE UEs) supporting cellular broadcast services, a numerology and a periodicity of a cell acquisition subframe (CAS) cannot be changed. Further, these new scenarios may mean a lower received signal-to-noise ratio (SNR) of channels in the CAS (as compared to scenarios covered in previous releases).

<CIT> relates to a method for providing enhanced physical downlink control channel (ePDCCH) in a multiple carrier communication system, which comprises receiving, at a wireless transmit and receive unit (WTRU), a configuration for monitoring an ePDCCH resource; configuring the WTRU to monitor the ePDCCH resource on a subframe based on the configuration; and monitoring, at the WTRU, the ePDCCH resource on the subframe.

<CIT> relates to a method for receiving or transmitting a broadcast signal in a wireless communication system and an apparatus therefor.

<CIT> relates to Technology for determining a common search space (CSS) from a physical resource block (PRB) indication for a stand-alone carrier type.

<CIT> relates to wireless telecommunications systems and more particularly to control channels in wireless telecommunications systems.

There still exists a need for improved wireless communication employing cellular broadcast services.

A solution is provided according to the subject matter of the independent claims.

In some aspects, a method of wireless communication, performed by a user equipment (UE), may include receiving a master information block (MIB) including enhancement information associated with an enhanced cell acquisition subframe (CAS) for a cellular broadcast service; and receiving the enhanced CAS, associated with the cellular broadcast service, based at least in part on the enhancement information associated with the enhanced CAS.

In some aspects, a UE for wireless communication may include memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to receive a MIB including enhancement information associated with an enhanced CAS for a cellular broadcast service; and receive the enhanced CAS, associated with the cellular broadcast service, based at least in part on the enhancement information associated with the enhanced CAS.

In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a UE, may cause the one or more processors to: receive a MIB including enhancement information associated with an enhanced CAS for a cellular broadcast service; and receive the enhanced CAS, associated with the cellular broadcast service, based at least in part on the enhancement information associated with the enhanced CAS.

In some aspects, an apparatus for wireless communication may include means for receiving a MIB including enhancement information associated with an enhanced CAS for a cellular broadcast service; and means for receiving the enhanced CAS, associated with the cellular broadcast service, based at least in part on the enhancement information associated with the enhanced CAS.

In some aspects, a method of wireless communication, performed by a base station, may include transmitting a MIB including enhancement information associated with an enhanced CAS for a cellular broadcast service; and transmitting the enhanced CAS, associated with the cellular broadcast service, based at least in part on the enhancement information associated with the enhanced CAS.

In some aspects, a base station for wireless communication may include memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to transmit a MIB including enhancement information associated with an enhanced CAS for a cellular broadcast service; and transmit the enhanced CAS, associated with the cellular broadcast service, based at least in part on the enhancement information associated with the enhanced CAS.

In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a base station, may cause the one or more processors to: transmit a MIB including enhancement information associated with an enhanced CAS for a cellular broadcast service; and transmit the enhanced CAS, associated with the cellular broadcast service, based at least in part on the enhancement information associated with the enhanced CAS.

In some aspects, an apparatus for wireless communication may include means for transmitting a master information block (MIB) including enhancement information associated with an enhanced CAS for a cellular broadcast service; and means for transmitting the enhanced CAS, associated with the cellular broadcast service, based at least in part on the enhancement information associated with the enhanced CAS.

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

The foregoing has outlined rather broadly the features and technical advantages of examples in accordance with the disclosure in order that the detailed description that follows may be better understood.

It is to be noted, however, that the appended drawings illustrate only some typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects.

This disclosure may, however, be embodied in many different forms and are not to be construed as limited to any specific structure or function presented throughout this disclosure. Based on the teachings herein one skilled in the art may appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any quantity of the aspects set forth herein. Any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

These apparatuses and techniques will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, or the like, or combinations thereof (collectively referred to as "elements").

It should be noted that while aspects may be described herein using terminology commonly associated with <NUM> or <NUM> wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems, such as <NUM> and later, including NR technologies.

A cellular broadcast service may be used to allow one or more base stations to broadcast communications for receipt by any UEs in a geographical area (for example, one or more cells) covered by the broadcast (such that any UE located in the one or more cells can receive the broadcasted communications). An example of a cellular broadcast service is a television service. In order to extend and enhance outreach and capabilities of cellular broadcast services (beyond the outreach and capabilities of cellular broadcast services in a legacy network, such as an LTE network), various use cases should be considered. Such use cases include, for example, a cellular broadcast service that uses a network with relatively large inter-site-distances (ISDs) between cells (for example, as compared to ISDs in a legacy LTE network), and a cellular broadcast service usable in a high mobility scenario (for example, when a given UE is located in a moving vehicle).

In order to support a cellular broadcast service in such scenarios, a design of new numerologies is needed (for example, in terms of OFDM subcarrier spacing, cyclic-prefix length, reference signal design, or the like). However, a challenge in such scenarios is to ensure that cell acquisition information - which informs a UE of details of the cellular broadcast scheme employed in the network-is received reliably by UEs.

Ensuring receipt of cell acquisition information is challenging because these new scenarios may mean a lower received signal-to-noise ratio (SNR) of channels in the CAS (as compared to scenarios considered in the design of cellular broadcast services for a legacy network). Further, ensuring receipt of cell acquisition information is challenging because, to be backward compatible with legacy UEs (for example, LTE UEs from earlier releases) supporting cellular broadcast services, a numerology and a periodicity of a cell acquisition subframe (CAS) cannot be changed. For example, in an LTE-based broadcast scenario, a CAS carries system information for broadcast (for example, OFDM subcarrier spacings employed in multicast-broadcast single-frequency network (MBSFN) subframes, cyclic prefix length, or the like), as well as the usual synchronization signals. In an LTE system, the CAS is one subframe long, has a periodicity of <NUM> milliseconds (ms), has legacy LTE numerology (in other words, <NUM> OFDM subcarrier spacing), carries typical LTE channels (for example, a PDCCH, a PDSCH, a PBCH, a PCFICH, and a physical hybrid automatic repeat request indicator channel (PHICH)), and carries a set of synchronization signals (for example, PSS and SSS). Per LTE specifications, the PDCCH can at most be three symbols in duration (for typical broadcast bandwidths of <NUM> and above). Notably, in the legacy PDCCH design, the largest size of a PDCCH candidate that a UE monitors in a common search space is eight control channel elements (CCEs) - which maps to <NUM> resource element groups (REGs) on the time-frequency grid in a specified pattern. A legacy UE can monitor a PDCCH candidate up to this size (in other words, an aggregation level of eight CCEs) and in this specified location. This CAS PDCCH design cannot be affected in order to ensure that a cellular broadcast service is backward compatible with legacy UEs.

Some aspects described herein provide CAS enhancements for cellular broadcast services. In some aspects, the CAS may be enhanced by defining an enhanced PDCCH candidate for monitoring by non-legacy UEs, where the enhanced CAS carries control information that is decodable by legacy UEs. In some aspects, the CAS may be enhanced by utilizing unused PHICH resources in the CAS (for example, to transmit an additional PCFICH, an additional cell-specific reference signal, an additional PDCCH, or the like). In some aspects, the CAS may be enhanced to carry other information associated with improving reception of the cell acquisition information. In some aspects, a master information block (MIB) may be used to carry information associated with the enhanced CAS. Additional details regarding such CAS enhancements are described below.

<FIG> is a block diagram illustrating an example wireless network <NUM> in accordance with various aspects of the present disclosure. The wireless network <NUM> may be a Long Term Evolution (LTE) network or some other wireless network, such as a <NUM> or NR network. The wireless network <NUM> may include a quantity of base stations (BSs) <NUM> (shown as BS 110a, BS 110b, BS 110c, and BS 110d) and other network entities. A BS is an entity that communicates with user equipment (UE(s)) and may also be referred to as a Node B, an eNodeB, an eNB, a gNB, a NR BS, a <NUM> node B (NB), an access point (AP), a transmit receive point (TRP), or the like, or combinations thereof (these terms are used interchangeably herein). In 3GPP, the term "cell" can refer to a coverage area of a BS or a BS subsystem serving this coverage area, depending on the context in which the term is used.

A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, or another type of cell. A macro cell may cover a relatively large geographic area (for example, several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (for example, a home) and may allow restricted access by UEs having association with the femto cell (for example, UEs in a closed subscriber group (CSG)). A BS may support one or multiple (for example, three) cells.

Wireless network <NUM> may be a heterogeneous network that includes BSs of different types, for example, macro BSs, pico BSs, femto BSs, relay BSs, or the like, or combinations thereof. For example, macro BSs may have a high transmit power level (for example, <NUM> to <NUM> Watts) whereas pico BSs, femto BSs, and relay BSs may have lower transmit power levels (for example, <NUM> to <NUM> Watts). A network controller <NUM> may couple to the set of BSs 102a, 102b, 110a and <NUM>10b, and may provide coordination and control for these BSs. The BSs may also communicate with one another, for example, directly or indirectly via a wireless or wireline backhaul.

In some aspects, a cell may not be stationary, rather, the geographic area of the cell may move in accordance with the location of a mobile BS. In some aspects, the BSs may be interconnected to one another or to one or more other BSs or network nodes (not shown) in the wireless network <NUM> through various types of backhaul interfaces such as a direct physical connection, a virtual network, or the like, or combinations thereof using any suitable transport network.

A relay station is an entity that can receive a transmission of data from an upstream station (for example, a BS or a UE) and send a transmission of the data to a downstream station (for example, a UE or a BS). A relay station may also be referred to as a relay BS, a relay base station, a relay, or the like, or combinations thereof.

UEs <NUM> (for example, 120a, 120b, 120c) may be dispersed throughout wireless network <NUM>, and each UE may be stationary or mobile. A UE may also be referred to as an access terminal, a terminal, a mobile station, a subscriber unit, a station, or the like, or combinations thereof. A UE may be a cellular phone (for example, a smart phone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or equipment, biometric sensors/devices, wearable devices (smart watches, smart clothing, smart glasses, smart wrist bands, smart jewelry (for example, smart ring, smart bracelet)), an entertainment device (for example, a music or video device, or a satellite radio), a vehicular component or sensor, smart meters/sensors, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless medium.

MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, or the like, or combinations thereof, that may communicate with a base station, another device (for example, remote device), or some other entity. A wireless node may provide, for example, connectivity for or to a network (for example, a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet-of Things (IoT) devices, or may be implemented as NB-IoT (narrowband internet of things) devices. UE <NUM> may be included inside a housing that houses components of UE <NUM>, such as processor components, memory components, or the like, or combinations thereof.

In general, any quantity of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular radio access technology (RAT) and may operate on one or more frequencies or frequency channels. A frequency may also be referred to as a carrier or the like, or combinations thereof.

In some aspects, two or more UEs <NUM> (for example, shown as UE 120a and UE 120e) may communicate directly with one another using one or more sidelink channels (for example, without using a base station <NUM> as an intermediary). For example, the UEs <NUM> may communicate using peer-to-peer (P2P) communications, device-to-device (D2D) communications, a vehicle-to-everything (V2X) protocol (for example, which may include a vehicle-to-vehicle (V2V) protocol, a vehicle-to-infrastructure (V2I) protocol, or the like, or combinations thereof), a mesh network, or the like, or combinations thereof. In this case, the UE <NUM> may perform scheduling operations, resource selection operations, or other operations described elsewhere herein as being performed by the base station <NUM>.

<FIG> is a block diagram <NUM> illustrating an example base station (BS) in communication with a user equipment (UE) in a wireless network in accordance with various aspects of the present disclosure.

At base station <NUM>, a transmit processor <NUM> may receive data from a data source <NUM> for one or more UEs, select one or more modulation and coding schemes (MCSs) for each UE based at least in part on channel quality indicators (CQIs) received from the UE, process (for example, encode) the data for each UE based at least in part on the MCS(s) selected for the UE, and provide data symbols for all UEs. Transmit processor <NUM> may also process system information (for example, for semi-static resource partitioning information (SRPI) or the like, or combinations thereof) and control information (for example, CQI requests, grants, upper layer signaling, or the like, or combinations thereof) and provide overhead symbols and control symbols. Transmit processor <NUM> may also generate reference symbols for reference signals (for example, the cell-specific reference signal (CRS)) and synchronization signals (for example, the primary synchronization signal (PSS) and secondary synchronization signal (SSS)). A transmit (TX) multiple-input multiple-output (MIMO) processor <NUM> may perform spatial processing (for example, precoding) on the data symbols, the control symbols, the overhead symbols, or the reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each MOD <NUM> may process a respective output symbol stream (for example, for OFDM or the like, or combinations thereof) to obtain an output sample stream. Each MOD <NUM> may further process (for example, convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. T downlink signals from MODs 232a through 232t may be transmitted via T antennas 234a through 234t, respectively. In accordance with various aspects described in more detail below, the synchronization signals can be generated with location encoding to convey additional information.

At UE <NUM>, antennas 252a through 252r may receive the downlink signals from base station <NUM> or other base stations and may provide received signals to R demodulators (DEMODs) 254a through 254r, respectively. Each DEMOD <NUM> may condition (for example, filter, amplify, downconvert, and digitize) a received signal to obtain input samples. Each DEMOD <NUM> may further process the input samples (for example, for OFDM or the like, or combinations thereof) to obtain received symbols. A MIMO detector <NUM> may obtain received symbols from all R DEMODs 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor <NUM> may process (for example, decode) the detected symbols, provide decoded data for UE <NUM> to a data sink <NUM>, and provide decoded control information and system information to a controller/processor <NUM>. A channel processor may determine a reference signal received power (RSRP), a received signal strength indicator (RSSI), a reference signal received quality (RSRQ), a channel quality indicator (CQI), or the like, or combinations thereof.

On the uplink, at UE <NUM>, a transmit processor <NUM> may receive and process data from a data source <NUM> as well as control information (for example, for reports including RSRP, RSSI, RSRQ, CQI, or the like, or combinations thereof) from controller/processor <NUM>. The symbols from transmit processor <NUM> may be precoded by a TX MIMO processor <NUM> if applicable, further processed by MODs 254a through 254r (for example, for discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM), orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) (CP-OFDM), or the like, or combinations thereof), and transmitted to base station <NUM>. At base station <NUM>, the uplink signals from UE <NUM> and other UEs may be received by antennas <NUM>, processed by DEMODs <NUM>, detected by a MIMO detector <NUM> if applicable, and further processed by a receive processor <NUM> to obtain decoded data and control information sent by UE <NUM>.

Controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, or any other component(s) of <FIG> may perform one or more techniques associated with cell acquisition subframe enhancements for cellular broadcast services, as described in more detail elsewhere herein. For example, controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, or any other component(s) of <FIG> may perform or direct operations of, for example, process <NUM> of <FIG>, process <NUM> of <FIG>, or other processes as described herein. Memories <NUM> and <NUM> may store data and program codes for base station <NUM> and UE <NUM>, respectively. A scheduler <NUM> may schedule UEs for data transmission on the downlink or uplink.

In some aspects, UE <NUM> may include means for receiving a master information block (MIB) including enhancement information associated with an enhanced cell acquisition subframe (CAS) for a cellular broadcast service, means for receiving the enhanced CAS, associated with the cellular broadcast service, based at least in part on the enhancement information associated with the enhanced CAS, or the like, or combinations thereof. In some aspects, such means may include one or more components of UE <NUM> described in connection with <FIG>.

In some aspects, base station <NUM> may include means for transmitting a MIB including enhancement information associated with an enhanced CAS for a cellular broadcast service, means for transmitting the enhanced CAS, associated with the cellular broadcast service, based at least in part on the enhancement information associated with the enhanced CAS, or the like, or combinations thereof. In some aspects, such means may include one or more components of base station <NUM> described in connection with <FIG>.

<FIG> is a block diagram illustrating an example frame structure <NUM> for use in a wireless network in accordance with various aspects of the present disclosure. For example, frame structure <NUM> may be used for frequency division duplexing (FDD) in a telecommunications system (for example, NR). The transmission timeline for each of the downlink and uplink directions may be partitioned into units of radio frames (sometimes referred to simply as "frames"). Each radio frame may have a predetermined duration (for example, <NUM> milliseconds (ms)) and may be partitioned into a set of Z (Z ≥ <NUM>) subframes (for example, with indices of <NUM> through Z-<NUM>). Each subframe may have a predetermined duration (for example, <NUM>) and may include a set of slots (for example, <NUM>m slots per subframe are shown in <FIG>, where m is numerology used for a transmission, such as <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or the like, or combinations thereof). For example, each slot may include fourteen symbol periods (for example, as shown in <FIG>), seven symbol periods, or another quantity of symbol periods. In a case where the subframe includes two slots (for example, when m = <NUM>), the subframe may include <NUM> symbol periods, where the <NUM> symbol periods in each subframe may be assigned indices of <NUM> through <NUM>-<NUM>. In some aspects, a scheduling unit for the FDD may be frame-based, subframe-based, slot-based, symbol-based, or the like, or combinations thereof.

While some techniques are described herein in connection with frames, subframes, slots, or the like, or combinations thereof, these techniques may equally apply to other types of wireless communication structures, which may be referred to using terms other than "frame," "subframe," "slot," or the like, or combinations thereof in <NUM> NR. In some aspects, a wireless communication structure may refer to a periodic time-bounded communication unit defined by a wireless communication standard or protocol. Additionally or alternatively, different configurations of wireless communication structures than those shown in <FIG> may be used.

In some telecommunications (for example, NR), a base station may transmit synchronization signals. For example, a base station may transmit a primary synchronization signal (PSS), a secondary synchronization signal (SSS), or the like, or combinations thereof, on the downlink for each cell supported by the base station.

In some aspects, the base station may transmit the PSS, the SSS, or the PBCH in accordance with a synchronization communication hierarchy (for example, a synchronization signal (SS) hierarchy) including multiple synchronization communications (for example, SS blocks), as described below in connection with <FIG>.

<FIG> is a block diagram illustrating an example synchronization communication hierarchy for use in a wireless communication network in accordance with various aspects of the present disclosure. The SS hierarchy, which is an example of a synchronization communication hierarchy. As shown in <FIG>, the SS hierarchy may include an SS burst set, which may include a plurality of SS bursts (identified as SS burst <NUM> through SS burst B-<NUM>, where B is a maximum quantity of repetitions of the SS burst that may be transmitted by the base station). As further shown, each SS burst may include one or more SS blocks (identified as SS block <NUM> through SS block (bmax_ss-<NUM>), where bmax_SS-<NUM> is a maximum quantity of SS blocks that can be carried by an SS burst).

In some aspects, an SS block includes resources that carry the PSS, the SSS, the PBCH, or other synchronization signals (for example, a tertiary synchronization signal (TSS)) or synchronization channels. In some aspects, multiple SS blocks are included in an SS burst, and the PSS, the SSS, or the PBCH may be the same across each SS block of the SS burst. In some aspects, the SS block may be at least four symbol periods in length, where each symbol carries one or more of the PSS (for example, occupying one symbol), the SSS (for example, occupying one symbol), or the PBCH (for example, occupying two symbols).

Similarly, in some aspects, one or more SS blocks of the SS burst may be transmitted in consecutive radio resources (for example, consecutive symbol periods) during one or more slots. Additionally or alternatively, one or more SS blocks of the SS burst may be transmitted in non-consecutive radio resources.

In some aspects, the SS bursts may have a burst period during which the SS blocks of the SS burst are transmitted by the base station in accordance with the burst period. In some aspects, the SS burst set may have a burst set periodicity, and the SS bursts of the SS burst set are transmitted by the base station in accordance with the fixed burst set periodicity.

The base station may transmit system information, such as system information blocks (SIBs) on a physical downlink shared channel (PDSCH) in some slots. The base station may transmit control information/data on a physical downlink control channel (PDCCH) in C symbol periods of a slot, where C may be configurable for each slot. The base station may transmit traffic data or other data on the PDSCH in the remaining symbol periods of each slot.

<FIG> is a block diagram <NUM> illustrating an example slot format <NUM> in accordance with various aspects of the present disclosure. Each resource block may cover a set of subcarriers (for example, <NUM> subcarriers) in one slot and may include a quantity of resource elements. Each resource element may cover one subcarrier in one symbol period (for example, in time) and may be used to send one modulation symbol, which may be a real or complex value.

An interlace structure may be used for each of the downlink and uplink for FDD in some telecommunications systems (for example, NR). For example, Q interlaces with indices of <NUM> through β - <NUM> may be defined, where Q may be equal to <NUM>, <NUM>, <NUM>, <NUM>, or some other value. Each interlace may include slots that are spaced apart by Q frames. In particular, interlace q may include slots q, q + Q, q + 2Q, etc., where q ∈ {<NUM>,. , Q-<NUM>}.

The serving BS may be selected based at least in part on various criteria such as received signal strength, received signal quality, path loss, or the like, or combinations thereof.

New Radio (NR) may refer to radios configured to operate in accordance with a new air interface (for example, other than Orthogonal Frequency Divisional Multiple Access (OFDMA)-based air interfaces) or fixed transport layer (for example, other than Internet Protocol (IP)). In aspects, NR may utilize OFDM with a cyclic prefix (CP) (herein referred to as cyclic prefix OFDM or CP-OFDM) or SC-FDM on the uplink, may utilize CP-OFDM on the downlink and include support for half-duplex operation using time division duplexing (TDD). In aspects, NR may, for example, utilize OFDM with a CP (herein referred to as CP-OFDM) or DFT-s-OFDM on the uplink, may utilize CP-OFDM on the downlink and include support for half-duplex operation using TDD. NR may include Enhanced Mobile Broadband (eMBB) service targeting wide bandwidth (for example, <NUM> megahertz (MHz) and beyond), millimeter wave (mmW) targeting high carrier frequency (for example, <NUM> gigahertz (GHz)), massive MTC (mMTC) targeting non-backward compatible MTC techniques, or mission critical targeting ultra reliable low latency communications (URLLC) service.

Each slot may indicate a link direction (for example, downlink (DL) or uplink (UL)) for data transmission and the link direction for each slot may be dynamically switched.

<FIG> is a diagram showing an example downlink (DL)-centric slot <NUM> or communication structure in accordance with various aspects of the present disclosure. The DL-centric slot (or wireless communication structure) may include a control portion <NUM> during which the scheduling entity (for example, UE or BS) transmits various scheduling information or control information corresponding to various portions of the DL-centric slot to the subordinate entity (for example, UE). The control portion <NUM> may exist in the initial or beginning portion of the DL-centric slot. In some configurations, the control portion <NUM> may be a physical DL control channel PDCCH, as indicated in <FIG>. In some aspects, the control portion <NUM> may include legacy PDCCH information, shortened PDCCH (sPDCCH) information), a control format indicator (CFI) value (for example, carried on a physical control format indicator channel (PCFICH)), one or more grants (for example, downlink grants, uplink grants, or the like, or combinations thereof), or the like, or combinations thereof.

The DL-centric slot may also include a DL data portion <NUM> during which the scheduling entity (for example, UE or BS) transmits DL data to the subordinate entity (for example, UE) using communication resources utilized to communicate DL data. The DL data portion <NUM> may sometimes be referred to as the payload of the DL-centric slot. In some configurations, the DL data portion <NUM> may be a PDSCH.

The DL-centric slot may also include an UL short burst portion <NUM> during which the subordinate entity (for example, UE) transmits reference signals or feedback to the scheduling entity (for example, UE or BS) using communication resources utilized to communicate UL data. The UL short burst portion <NUM> may sometimes be referred to as an UL burst, an UL burst portion, a common UL burst, a short burst, an UL short burst, a common UL short burst, a common UL short burst portion, or various other suitable terms. In some aspects, the UL short burst portion <NUM> may include one or more reference signals. Additionally or alternatively, the UL short burst portion <NUM> may include feedback information corresponding to various other portions of the DL-centric slot. For example, the UL short burst portion <NUM> may include feedback information corresponding to the control portion <NUM> or the data portion <NUM>. Nonlimiting examples of information that may be included in the UL short burst portion <NUM> include an acknowledgement (ACK) signal (for example, a physical uplink control channel (PUCCH) ACK, a physical uplink shared channel (PUSCH) ACK, or an immediate ACK), a negative acknowledgement (NACK) signal (for example, a PUCCH NACK, a PUSCH NACK, or an immediate NACK), a scheduling request (SR), a buffer status report (BSR), a hybrid automatic repeat request (HARQ) indicator, a channel state indication (CSI), a channel quality indicator (CQI), a sounding reference signal (SRS), a demodulation reference signal (DMRS), PUSCH data, or various other suitable types of information. The UL short burst portion <NUM> may include additional or alternative information, such as information pertaining to RACH procedures, scheduling requests, and various other suitable types of information.

This time separation may sometimes be referred to as a gap, a guard period, a guard interval, or various other suitable terms. This separation provides time for the switch-over from DL communication (for example, reception operation by the subordinate entity (for example, BS or UE)) to UL communication (for example, transmission by the subordinate entity (for example, UE)). The foregoing provides some examples of a DL-centric wireless communication structure, but alternative structures having similar features may exist without deviating from the aspects described herein.

<FIG> is a diagram showing an example uplink (UL)-centric slot <NUM> or communication structure in accordance with various aspects of the present disclosure. The UL-centric slot (or wireless communication structure) may include a control portion <NUM>. The control portion <NUM> may exist in the initial or beginning portion of the UL-centric slot. The control portion <NUM> in <FIG> may be similar to the control portion <NUM> described above with reference to <FIG>. The UL-centric slot may also include an UL long burst portion <NUM>. The UL long burst portion <NUM> may sometimes be referred to as the payload of the UL-centric slot. The UL portion may refer to the communication resources utilized to communicate UL data from the subordinate entity (for example, UE) to the scheduling entity (for example, UE or BS). In some configurations, the control portion <NUM> may be a physical DL control channel PDCCH.

This time separation may sometimes be referred to as a gap, guard period, guard interval, or various other suitable terms. This separation provides time for the switch-over from DL communication (for example, reception operation by the scheduling entity) to UL communication (for example, transmission operation by the scheduling entity).

The UL-centric slot may also include an UL short burst portion <NUM>. The UL short burst portion <NUM> in <FIG> may be similar to the UL short burst portion <NUM> described above with reference to <FIG>, and may include any of the information described above in connection with <FIG>. The foregoing is merely one example of an UL-centric wireless communication structure, and alternative structures having similar features may exist without deviating from the aspects described herein.

In some circumstances, two or more subordinate entities (for example, UEs) may communicate with each other using side link signals. Real-world applications of such side link communications may include public safety, proximity services, UE-to-network relaying, V2V communications, Internet of Everything (IoE) communications, IoT communications, mission-critical mesh, or various other suitable applications. Generally, a sidelink signal may refer to a signal communicated from one subordinate entity (for example, UE1) to another subordinate entity (for example, UE2) without relaying that communication through the scheduling entity (for example, UE or BS), even though the scheduling entity may be utilized for scheduling or control purposes. In some aspects, the side link signals may be communicated using a licensed spectrum band; in other aspects, the sidelink signals may be communicated using an unlicensed spectrum band.

In one example, a wireless communication structure, such as a frame, may include both UL-centric slots and DL-centric slots. In this example, the ratio of UL-centric slots to DL-centric slots in a frame may be dynamically adjusted based at least in part on the amount of UL data and the amount of DL data that are transmitted. For example, if there is more UL data, then the ratio of UL-centric slots to DL-centric slots may be increased. Conversely, if there is more DL data, then the ratio of UL-centric slots to DL-centric slots may be decreased.

A cellular broadcast service may be used to allow one or more base stations to broadcast communications for receipt by any UEs in a geographical area (for example, one or more cells) covered by the broadcast (such that any UE located in the one or more cells can receive the broadcasted communications). An example of a cellular broadcast service is a television service. In order to extend and enhance outreach and capabilities of cellular broadcast services (beyond the outreach and capabilities of cellular broadcast services in a legacy network, such as an LTE network), various use cases should be considered. Such use cases include, for example, a cellular broadcast service that uses a network with relatively large ISDs between cells (for example, as compared to ISDs in a legacy LTE network), and a cellular broadcast service usable in a high mobility scenario (for example, when a given UE is located in a moving vehicle).

Ensuring receipt of cell acquisition information is challenging because these new scenarios may mean a lower received SNR of channels in the CAS (as compared to scenarios considered in the design of cellular broadcast services for a legacy network). Further, ensuring receipt of cell acquisition information is challenging because, to be backward compatible with legacy UEs (for example, LTE UEs) supporting cellular broadcast services, a numerology and a periodicity of a cell acquisition subframe (CAS) cannot be changed. For example, in an LTE-based broadcast scenario, a CAS carries system information for broadcast (for example, OFDM subcarrier spacings employed in MBSFN subframes, cyclic prefix length, or the like), as well as the usual synchronization signals. In an LTE system, the CAS is one subframe long, has a periodicity of <NUM> milliseconds (ms), has legacy LTE numerology (in other words, <NUM> OFDM subcarrier spacing), carries typical LTE channels (for example, a PDCCH, a PDSCH, a PBCH, a PCFICH, and a PHICH), and carries a set of synchronization signals (for example, PSS and SSS). Per LTE specifications, the PDCCH can at most be three symbols in duration (for typical broadcast bandwidths of <NUM> and above). Notably, in the legacy PDCCH design, the largest size of a PDCCH candidate that a UE monitors in a common search space is eight CCEs - which maps to <NUM> REGs on the time-frequency grid in a specified pattern. A PDCCH candidate is a possible location for a PDCCH (in other words, a set of resources in which it is possible for the PDCCH to be communicated). A common search space is a set of resources comprising all of the PDCCH candidates associated with a group of UEs (in other words, a group of sets of resources in which it is possible for the PDCCH to be communicated to the group of UEs). A legacy UE can monitor a PDCCH candidate up to this size (in other words, an aggregation level of eight CCEs) and in this specified location. This CAS design cannot be changed, in order to ensure that a cellular broadcast service is backward compatible with legacy UEs.

Some aspects described herein provide CAS enhancements for cellular broadcast services. In some aspects, the CAS may be enhanced by defining an enhanced PDCCH candidate for monitoring by non-legacy UEs, where the enhanced CAS carries control information that is decodable by legacy UEs. In some aspects, the CAS may be enhanced by utilizing unused PHICH resources in the CAS (for example, to transmit an additional PCFICH, an additional PDCCH, an additional cell-specific reference signal, or the like). In some aspects, the CAS may be enhanced to carry other information associated with improving reception of the cell acquisition information. In some aspects, a MIB may be used to carry information associated with the enhanced CAS. Additional details regarding such CAS enhancements are described below.

<FIG> are diagrams illustrating examples associated with CAS enhancements for cellular broadcast services in accordance with various aspects of the present disclosure.

In example <NUM> of <FIG>, in a first operation <NUM>, a base station (for example, base station <NUM>) transmits a MIB including enhancement information associated with an enhanced CAS for a cellular broadcast service. In some aspects, the base station transmits the MIB in a PBCH to be received by one or more non-legacy UEs. In some aspects, the enhancement information may be included in one or more spare or unused bits in the MIB (in other words, one or more bits that a legacy UE is configured to ignore when receiving the MIB). The base station may transmit the MIB such that a legacy portion of the MIB (in other words, bits that are not ignored by the legacy UEs) is unaffected in order to allow legacy UEs to receive the MIB. A non-legacy UE is a UE configured to access the cellular broadcast service via a non-legacy network, such as a <NUM> cellular broadcast network (rather than accessing the cellular broadcast service via a legacy network).

An enhanced CAS, as described herein, is a CAS including information that improves reliability and coverage associated with receipt of the CAS by the non-legacy UE (in other words, to improve a likelihood that the non-legacy UE will successfully receive the CAS). The enhancement information, included in the MIB, is information describing enhancements present in the enhanced CAS. In some aspects, the enhancement information is used to indicate the enhancements present in the CAS (for example, in order to allow a non-legacy UE that receives the enhanced CAS to interpret information included in the CAS). In a second operation <NUM>, a non-legacy UE (for example, a UE <NUM>) receives the MIB including the enhancement information. Further operations of <FIG> are described below, followed by particular examples and operations associated with enhancement information and enhanced CASs.

In a third operation <NUM>, the base station transmits the enhanced CAS, associated with the cellular broadcast service, based at least in part on the enhancement information associated with the enhanced CAS. In some aspects, the base station transmits the CAS in accordance with the enhancement information (such that the non-legacy UE can receive and interpret the enhanced CAS based at least in part on the enhancement information previously received by the UE). Illustrative examples of enhanced CASs are described below with regard to <FIG>.

In a fourth operation <NUM>, the non-legacy UE receives the enhanced CAS, associated with the cellular broadcast service, based at least in part on the enhancement information associated with the enhanced CAS. For example, the non-legacy UE may receive the enhanced CAS and interpret information included in the CAS in accordance with the enhancement information.

In some aspects, the enhancement to the CAS may include an enhancement associated with a PDCCH. For example, in some aspects, the enhancement information may include an indication that the non-legacy UE is to monitor an enhanced PDCCH candidate in a common search space of the enhanced CAS. The enhanced PDCCH candidate is a PDCCH candidate having an aggregation level greater than a legacy maximum aggregation level (for example, greater than a legacy maximum aggregation level of eight). For example, the enhanced PDCCH candidate may have an aggregation level greater than eight, such as <NUM>, <NUM>, or the like. In some aspects, the enhanced PDCCH candidate may have an aggregation level up to <NUM> (in other words, less than or equal to <NUM>). In some aspects, the enhanced PDCCH candidate may have at least one time-frequency resource in common with a legacy PDCCH candidate in the common search space of the enhanced CAS (such that the enhanced PDCCH candidate at least partially overlaps the legacy PDCCH candidate).

In some aspects, when the enhancement information includes an indication that the non-legacy UE is to monitor an enhanced PDCCH candidate, the base station may generate the PDCCH to be transmitted in resources of the enhanced PDCCH candidate in the common search space of the enhanced CAS associated with the cellular broadcast service, and may transmit the PDCCH in the resources of the enhanced PDCCH candidate in the common search space of the CAS associated with the cellular broadcast service. Here, when receiving the enhanced CAS, the non-legacy UE may monitor the enhanced PDCCH candidate in association with receiving the PDCCH included in the common search space of the CAS and, as a result, may receive the PDCCH in resources of the common search space based at least in part on monitoring the enhanced PDCCH candidate. In some aspects, the enhanced PDCCH candidate may be within three or fewer PDCCH symbols in the enhanced CAS.

In some aspects, control information included in the PDCCH (for example, DCI), is decodable by a legacy UE configured to monitor a legacy PDCCH candidate in the common search space of the enhanced CAS. For example, when generating the PDCCH, the base station may map a first encoded bit stream, associated with control information included in the PDCCH, to a first set of resources, and may map a second encoded bit stream, associated with the control information included in the PDCCH, to a second set of resources. In other words, the base station may map a first bit stream comprising the control information to a first legacy set of resources, and may map a second bit stream comprising the control information (the same control information) to a second set of resources. Here, the first set of resources is included in both the enhanced PDCCH candidate and the legacy PDCCH candidate, and the second set of resources is included in the enhanced PDCCH candidate only. A legacy UE may receive the control information in the first set of resources based at least in part on monitoring the legacy PDCCH candidate, while the non-legacy UE may receive the control information in the first and/or the second set of resources based at least in part on monitoring the enhanced PDCCH candidate. Thus, the non-legacy UE may see a lower code rate and, therefore, experience better reliability as compared to the legacy UE. Notably, in this example, the encoding and mapping for the legacy portion is not altered, but a separate encoded stream (corresponding to the same information) is mapped in additional time-frequency locations.

As another example, when generating the PDCCH, the base station may map a single encoded bit stream, associated with the control information, to resources associated with the legacy PDCCH candidate and the enhanced PDCCH candidate. Here, the base station may generate the PDCCH such that the control information is decodable from a first portion of the single encoded bit stream based at least in part on monitoring the legacy PDCCH candidate, and such that the control information is decodable from the first portion of the single encoded bit stream and a second portion of the single encoded bit stream based at least in part on monitoring the enhanced PDCCH candidate. In such a case, the control information may be decodable from the first portion of the single encoded bit stream (for example, such that the legacy UE can decode the control information from only the first portion of the single encoded bit stream), while the second portion of the single encoded bit stream provides, to the non-legacy UE, reliability and enhanced coverage associated with decoding the control information. In some aspects, the second portion of the single encoded bit stream is scrambled/descrambled or rotated based at least in part on a characteristic associated with the enhanced CAS, such as a frame number associated with the CAS. In some aspects, performing such operations based at least in part on the characteristic may facilitate cross-subframe combining of PDCCHs, as described below.

An example using this process for generating the PDDCH is provided below. In a first operation, an aggregation level (for example, L = <NUM>, <NUM>) for the new PDCCH candidate is defined. In a next operation, an encoder output from an encoder (for example, a tail-biting convolutional coder (TBCC) encoder) may be rate matched to a length corresponding to L × <NUM> × <NUM> × <NUM> = <NUM> × L bits. Here, an order and position of the first <NUM> × <NUM> bits (in other words, the bits corresponding to the legacy PDCCH candidate comprising <NUM> CCEs) are unchanged. In a next operation, an independent bit-level operation (for example, scrambling) may be performed on the other {<NUM> × <NUM> + <NUM> to <NUM> × L}bits (in other words, the non-legacy bits). In some aspects, this bit-level operation may be performed based at least in part on a frame number (for example, to facilitate cross-subframe combining). In some aspects, the bit stream is then scrambled by a cell identifier specific sequence as described for example in TS <NUM> Section <NUM>. In a next operation, the bit stream (comprising legacy bits in unchanged positions, and additional bits from the rate-matching output, together with <NIL> elements) may be mapped for example per procedures in TS <NUM> Section <NUM>. <NUM> onwards. Here, the mapping operation as described in TS <NUM> Section <NUM>. <NUM> may ensure that the position of the modulated legacy bits in the time-frequency grid are unchanged, while the additional bits may will be mapped to REGs that were otherwise mapping <NIL> elements.

<FIG> is a diagram of an example of enhanced CAS including a PDCCH enhancement. In <FIG>, the PDCCH REGs labeled "PDCCH L" correspond to bits generated in a manner that matches legacy, while the PDCCH REGs labeled "PDCCH E" correspond to bits generated beyond the legacy bit stream. In this example, the legacy PDCCH candidate corresponds to the PDCCH REGs labeled as "PDCCH L", while the enhanced PDCCH candidate corresponds to the combination of the PDCCH REGs labeled as "PDCCH L" and the PDCCH REGs labeled as "PDCCH E".

In some aspects, the non-legacy UE may combine the PDCCH, received based at least in part on monitoring the enhanced PDCCH candidate, with another PDCCH included in a common search space of another CAS. For example, the enhancement information may include an indication that the non-legacy UE is to combine the PDCCH, to be received in the common search space of the CAS, with another PDCCH (for example, a PDCCH received in a common search space of a previously received CAS, a PDCCH to be received in a common search space of a CAS to be received at a later time, or the like). Here, the non-legacy UE may receive the PDCCH, and may combine the PDCCH with the other PDCCH, accordingly. In this way, cross-subframe combining of PDCCHs may be achieved. In some aspects, an operation performed on a bit stream associated with the control information may be performed based at least in part on a characteristic of the enhanced CAS in order to facilitate cross-subframe combining (such that the non-legacy UE may identify a manner or order in which the PDCCHs are to be combined).

In some aspects, because the mode of operation is downlink-only for broadcast, PHICH resources may be unutilized. Thus, in some aspects, the enhancement information may include an indication to receive an additional PCFICH (in other words, information that identifies a number of control symbols in the enhanced CAS) in at least one symbol of a set of resources associated with the PHICH. Here, when transmitting the enhanced CAS, the base station may transmit the additional PCFICH (the same PCFICH that is transmitted in a set of symbols typically used to transmit the PCFICH) in the at least one symbol of the set of resources associated with the PHICH. The non-legacy UE, when receiving the enhanced CAS, may receive the additional PCFICH in the at least one symbol of the set of resources associated with the PHICH based at least in part on the enhancement information. In this way, the enhanced CAS may be used to improve coverage of the PCFICH.

<FIG> is a diagram of an example of enhanced CAS including such an additional PCFICH. In <FIG>, the legacy PDCCH candidate corresponds to the PDCCH REGs labeled as "PDCCH L" and the enhanced PDCCH candidate corresponds to the combination of the PDCCH REGs labeled as "PDCCH L" and the PDCCH REGs labeled as "PDCCH E", as described above in association with <FIG>. As further shown in <FIG>, a PCFICH may be carried in a REG labeled as "PCFICH L," and an additional PCFICH may be carried in previously unused PHICH resources, which are labeled as "PCFICH E" in <FIG>.

In some aspects, as noted above, because the mode of operation is downlink-only for broadcast, PHICH resources may be unutilized. In some aspects, the enhancement information may include an indication to receive an additional PDCCH in at least one symbol of the set of resources associated with the PHICH. Here, when transmitting the enhanced CAS, the base station may transmit the additional PDCCH (for example, a separate PDCCH bit stream that is mapped to the PHICH resources) in the at least one symbol of the set of resources associated with the PHICH. The non-legacy UE, when receiving the enhanced CAS, may receive the additional PDCCH in the at least one symbol of the set of resources associated with the PHICH based at least in part on the enhancement information. In this way, the enhanced CAS may be used to further improve coverage of the PDCCH.

<FIG> is a diagram of an example of enhanced CAS including such an additional PDCCH. In <FIG>, the legacy PDCCH candidate corresponds to the PDCCH REGs labeled as "PDCCH L" and the enhanced PDCCH candidate corresponds to the combination of the PDCCH REGs labeled as "PDCCH L" and the PDCCH REGs labeled as "PDCCH E", as described above in association with <FIG>. As further shown in <FIG>, an additional PDCCH (identified as PDCCH2) may be carried in previously unused PHICH resources, which are labeled as "PDCCH2 E" in <FIG>.

In some aspects, the enhancement information includes information that identifies a number of symbols associated with the PDCCH. In this way, backup to the PCFICH may be provided.

In some aspects, as noted above, because the mode of operation is downlink-only for broadcast, PHICH resources may be unutilized. In some aspects, the enhancement information may include an indication to receive an additional cell-specific reference signal (CRS) in at least one symbol of the set of resources associated with the PHICH. Here, when transmitting the enhanced CAS, the base station may transmit the additional CRS (for example, the same CRS that is transmitted in a set of symbols typically used to transmit the CRS) in the at least one symbol of the set of resources associated with the PHICH. The non-legacy UE, when receiving the enhanced CAS, may receive the additional CRS in the at least one symbol of the set of resources associated with the PHICH based at least in part on the enhancement information. In this way, the enhanced CAS may be used to further improve channel estimation. In some aspects, the additional cell-specific reference signal is scrambled/descrambled based at least in part on a cell identifier or a frame number. In some aspects, at least one symbol in which the additional cell-specific reference signal is communicated is dependent on a cell identifier.

In some scenarios, there may be only one CRS port configured by the base station. Here, REGs may not map any information to REs that corresponding to a second CRS port, even though no CRS is transmitted in the REs corresponding to the second CRS port. A legacy UE makes no assumption about contents of the REs corresponding to the second CRS port when only one CRS port is configured by the base station (in other words, the legacy UE ignores the REs corresponding to the second CRS port). In such a scenario, with an appropriate MIB indication to a non-legacy UE, an additional cell-specific reference signal can be transmitted in the (otherwise empty) REs corresponding to the second CRS port. Thus, the REs corresponding to the second CRS port may be used for transmission of an additional CRS that can be used to improve channel estimation. Thus, in some aspects, the enhancement information may include an indication to receive an additional CRS in one or more resources corresponding to a CRS port that is configured on the UE. Here, when receiving the enhanced CAS comprises, the UE may receive the additional cell-specific reference signal in the one or more resources corresponding to the CRS port. In some aspects, the additional CRS may be scrambled/descrambled based at least in part on at least one of a cell identifier, an OFDM symbol number, a frame number, or the like.

In some aspects, the enhancement information may include information that identifies a quantity of blind decoding attempts that the non-legacy UE is to perform in association with receiving the PDCCH in the common search space of the enhanced CAS. The quantity of blind decoding attempts may be different from legacy because the enhanced PDCCH candidate is larger in size than the legacy PDCCH candidate, thereby consuming additional UE resources to decode. In some aspects, the enhancement information may include an indication that the non-legacy UE is not to monitor at least one legacy PDCCH candidate in a common search space of the enhanced CAS (for example, in order to conserve resources of the non-legacy UE). In some aspects, the enhancement information may include an indication that the UE is to perform a single decoding attempt (in other words, no blind decoding) in a common search space of the enhanced CAS.

In some aspects, the enhancement information includes an indication of whether a particular CAS enhancement is active in the enhanced CAS. For example, the enhancement information may include information explicitly indicating whether one or more of the above described CAS enhancements are active (for example, cross-subframe combining, enhanced PDCCH candidate, or the like). As another example, the enhancement information may include information implicitly indicating whether one or more of the CAS enhancements are active. As a particular example, when the enhancement information includes information that identifies a quantity of blind decoding attempts that the non-legacy UE is to perform in association with receiving the PDCCH in the common search space of the enhanced CAS, this information may serve as an indication that the one or more other CAS enhancements are active.

In some aspects, the enhancement information may include an indication that the non-legacy UE is to skip decoding of a PDCCH. This may be the case when, for example, system and control information are mapped to a PDSCH (rather than a PDCCH). In some aspects, skipping the decoding of the PDCCH reduces decoding complexity and improves reliability for the non-legacy UE. In some aspects, the indication to skip the decoding of the PDCCH may include information that identifies a start symbol of a physical downlink shared channel (PDSCH). In some aspects, the indication to skip the decoding of the PDCCH may include other information, such as information that identifies a number of control symbols associated with skipping the decoding of the PDCCH, a transport block size of a system information block associated with skipping the decoding of the PDCCH, a resource allocation of the system information block associated with skipping the decoding of the PDCCH, a subframe associated with skipping the decoding of the PDCCH, or the like.

<FIG> is a diagram illustrating an example process <NUM> performed, for example, by a UE, in accordance with various aspects of the present disclosure. Example process <NUM> is an example where a UE (for example, UE <NUM> or the like) performs operations associated with cell acquisition subframe enhancements.

As shown in <FIG>, in some aspects, process <NUM> may include receiving a MIB including enhancement information associated with an enhanced CAS for a cellular broadcast service (block <NUM>). For example, the UE (for example, using receive processor <NUM>, controller/processor <NUM>, memory <NUM>, or the like) may receive a MIB including enhancement information associated with an enhanced CAS for a cellular broadcast service, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include receiving the enhanced CAS, associated with the cellular broadcast service, based at least in part on the enhancement information associated with the enhanced CAS (block <NUM>). For example, the UE (for example, using receive processor <NUM>, controller/processor <NUM>, memory <NUM>, or the like) may receive the enhanced CAS, associated with the cellular broadcast service, based at least in part on the enhancement information associated with the enhanced CAS, as described above.

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

In a first aspect, the enhancement information includes an indication that the UE is to monitor an enhanced PDCCH candidate in a common search space of the enhanced CAS. Here, receiving the enhanced CAS may include monitoring the enhanced PDCCH candidate in association with receiving a PDCCH included in the common search space of the CAS service (the enhanced PDCCH candidate having an aggregation level greater than a legacy maximum aggregation level, and having at least one resource in common with a legacy PDCCH candidate in the common search space of the enhanced CAS), and receiving the PDCCH in resources of the common search space based at least in part on monitoring the enhanced PDCCH candidate. That is, when the enhancement information includes an indication that the UE is to monitor an enhanced PDCCH candidate in a common search space of the enhanced CAS, in some examples, receiving the enhanced CAS includes monitoring the enhanced PDCCH candidate in association with receiving a PDCCH included in the common search space of the CAS service, and receiving the PDCCH in resources of the common search space based at least in part on monitoring the enhanced PDCCH candidate.

In a second aspect, in combination with the first aspect, the enhanced PDCCH candidate is within three or fewer PDCCH symbols in the enhanced CAS.

In a third aspect, in combination with any one or more of the first and second aspects, the legacy maximum aggregation level is eight.

In a fourth aspect, in combination with any one or more of the first through third aspects, control information, included in the PDCCH, is decodable by a legacy UE configured to monitor the legacy PDCCH candidate in the common search space of the enhanced CAS.

In a fifth aspect, in combination with any one or more of the first through fourth aspects, control information, included in the PDCCH, comprises a first encoded bit stream mapped to a first set of resources and a second encoded bit stream mapped to a second set of resources. Here, the first set of resources is included in both the enhanced PDCCH candidate and the legacy PDCCH candidate, and the second set of resources is included in the enhanced PDCCH candidate only.

In a sixth aspect, in combination with any one or more of the first through fourth aspects, control information, included in the PDCCH, comprises a single encoded bit stream. Here, the control information is decodable from a first portion of the single encoded bit stream based at least in part on monitoring the legacy PDCCH candidate, and the control information is decodable from the first portion of the single encoded bit stream and a second portion of the single encoded bit stream based at least in part on monitoring the enhanced PDCCH candidate.

In a seventh aspect, in combination with the sixth aspect, the control information is decodable from the first portion of the single encoded bit stream, while the second portion of the single encoded bit stream provides reliability and enhanced coverage associated with decoding the control information.

In an eighth aspect, in combination with any one or more of the sixth and seventh aspects, the second portion of the single encoded bit stream is descrambled or rotated based at least in part on a characteristic associated with the enhanced CAS.

In a ninth aspect, in combination with any one or more of the first through eighth aspects, the UE may combine the PDCCH with another PDCCH included in a common search space of another CAS. That is, in some examples, the process <NUM> may include combining the PDCCH with another PDCCH included in a common search space of another CAS based at least in part on an indication included in the MIB.

In a tenth aspect, in combination with the ninth aspect, the PDCCH is combined with the other PDCCH based at least in part on an indication included in the MIB.

In an eleventh aspect, in combination with any one or more of the first through tenth aspects, the enhanced PDCCH candidate has an aggregation level of <NUM>.

In a twelfth aspect, in combination with any one or more of the first through eleventh aspects, the enhanced PDCCH candidate has an aggregation level that is less than or equal to <NUM>.

In a thirteenth aspect, alone or in combination with any one or more of the first through twelfth aspects, the enhancement information includes an indication to receive an additional PCFICH in at least one symbol of a set of resources associated with a PHICH. Here, receiving the enhanced CAS may include receiving the additional PCFICH in the at least one symbol of the set of resources associated with the PHICH.

In a fourteenth aspect, alone or in combination with any one or more of the first through thirteenth aspects, the enhancement information includes an indication to receive an additional PDCCH in at least one symbol of a set of resources associated with a PHICH. Here, receiving the enhanced CAS may include receiving the additional PDCCH in the at least one symbol of the set of resources associated with the PHICH.

In a fifteenth aspect, alone or in combination with any one or more of the first through fourteenth aspects, the enhancement information includes information that identifies a number of symbols associated with a PDCCH.

In a sixteenth aspect, alone or in combination with any one or more of the first through fifteenth aspects, the enhancement information includes information that identifies a quantity of blind decoding attempts that the UE is to perform in association with receiving a PDCCH in a common search space of the enhanced CAS.

In a seventeenth aspect, alone or in combination with any one or more of the first through sixteenth aspects, the enhancement information includes an indication that the UE is not to monitor at least one legacy PDCCH candidate in a common search space of the enhanced CAS.

In an eighteenth aspect, alone or in combination with any one or more of the first through seventeenth aspects, the enhancement information includes an indication that the UE is to perform a single decoding attempt in a common search space of the enhanced CAS.

In a nineteenth aspect, alone or in combination with any one or more of the first through eighteenth aspects, the enhancement information includes an indication of whether a particular CAS enhancement is active in the enhanced CAS.

In a twentieth aspect, the enhancement information includes an indication that the UE is to skip decoding of a PDCCH.

In a twenty-first aspect, in combination with the twentieth aspect, the indication includes information that identifies a start symbol of a PDSCH.

In a twenty-second aspect, in combination with any one or more of the twentieth and twenty-first aspects, the indication includes information that identifies at least one of a number of control symbols associated with skipping the decoding of the PDCCH, a transport block size of a system information block associated with skipping the decoding of the PDCCH, a resource allocation of the system information block associated with skipping the decoding of the PDCCH, or a subframe associated with skipping the decoding of the PDCCH.

In a twenty-third aspect, alone or in combination with any one or more of the first through twenty-second aspects, the enhancement information includes an indication to receive an additional CRS in at least one symbol of a set of resources associated with a PHICH. Here, when receiving the enhanced CAS, the UE may receive the additional cell-specific reference signal in the at least one symbol of the set of resources associated with the PHICH.

In a twenty-fourth aspect, in combination with the twenty-third aspect, the additional cell-specific reference signal is descrambled based at least in part on a cell identifier or a frame number.

In a twenty-fifth aspect, in combination with any one or more of the twenty-third aspect and twenty-fourth aspects, the at least one symbol in which the additional cell-specific reference signal is received is dependent on a cell identifier.

In a twenty-sixth aspect, alone or in combination with any one or more of the first through twenty-fifth aspects, the enhancement information includes an indication to receive an additional CRS in one or more resources corresponding to a CRS port that is to be ignored by legacy UEs. Here, when receiving the enhanced CAS, the UE may receive the additional cell-specific reference signal in the one or more resources corresponding to the CRS port.

In a twenty-seventh aspect, in combination with the twenty-sixth aspect, the additional CRS is scrambled based at least in part on at least one of a cell identifier, a symbol number, or a frame number.

<FIG> is a diagram illustrating an example process <NUM> performed, for example, by a base station, in accordance with various aspects of the present disclosure. Example process <NUM> is an example where a base station (for example, base station <NUM> and/or the like) performs operations associated with cell acquisition subframe enhancements.

As shown in <FIG>, in some aspects, process <NUM> may include transmitting a MIB including enhancement information associated with an enhanced CAS for a cellular broadcast service (block <NUM>). For example, the base station (for example, using transmit processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may transmit a MIB including enhancement information associated with an enhanced CAS for a cellular broadcast service, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include transmitting the enhanced CAS, associated with the cellular broadcast service, based at least in part on the enhancement information associated with the enhanced CAS (block <NUM>). For example, the base station (for example, using transmit processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may transmit the enhanced CAS, associated with the cellular broadcast service, based at least in part on the enhancement information associated with the enhanced CAS, as described above.

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

In a first aspect, the enhancement information includes an indication that a UE (for example, UE <NUM>) is to monitor an enhanced PDCCH candidate in a common search space of the enhanced CAS. Here, transmitting the enhanced CAS may include generating the PDCCH to be transmitted in resources of the enhanced PDCCH candidate in the common search space of the enhanced CAS associated with the cellular broadcast service (the enhanced PDCCH candidate having an aggregation level greater than a legacy maximum aggregation level, and having at least one resource in common with a legacy PDCCH candidate in the common search space of the enhanced CAS), and transmitting the PDCCH in the resources of the enhanced PDCCH candidate in the common search space of the CAS associated with the cellular broadcast service. That is, when the enhancement information includes an indication that a UE is to monitor an enhanced PDCCH candidate in a common search space of the enhanced CAS, in some examples, transmitting the enhanced CAS includes generating the PDCCH to be transmitted in resources of the enhanced PDCCH candidate in the common search space of the enhanced CAS associated with the cellular broadcast service, and transmitting the PDCCH in the resources of the enhanced PDCCH candidate in the common search space of the enhanced CAS associated with the cellular broadcast service.

In a fourth aspect, in combination with any one or more of the first through third aspects, the base station may encode control information, included in the PDCCH, such that the control information is decodable by a legacy user equipment configured to monitor the legacy PDCCH candidate in the common search space of the enhanced CAS. That is, in some examples, the process <NUM> includes encoding control information, included in the PDCCH, such that the control information is decodable by a legacy UE configured to monitor the legacy PDCCH candidate in the common search space of the enhanced CAS.

In a fifth aspect, in combination with any one or more of the first through fourth aspects, the base station may map a first encoded bit stream, associated with control information included in the PDCCH, to a first set of resources, and map a second encoded bit stream, associated with the control information included in the PDCCH, to a second set of resources. Here, the first set of resources is included in both the enhanced PDCCH candidate and the legacy PDCCH candidate, and the second set of resources is included in the enhanced PDCCH candidate only.

In a ninth aspect, in combination with any one or more of the first through eighth aspects, the enhancement information includes an indication that a UE is to combine the PDCCH with another PDCCH included in a common search space of another CAS.

In a tenth aspect, in combination with any one or more of the first through ninth aspects, the enhanced PDCCH candidate has an aggregation level of <NUM>.

In an eleventh aspect, in combination with any one or more of the first through tenth aspects, the enhanced PDCCH candidate has an aggregation level that is less than or equal to <NUM>.

In a twelfth aspect, alone or in combination with any one or more of the first through eleventh aspects, the enhancement information includes an indication that a UE is to receive an additional PCFICH in at least one symbol of a set of resources associated with a PHICH.

In a thirteenth aspect, in combination with the twelfth aspect, transmitting the enhanced CAS includes transmitting the additional PCFICH in the at least one symbol of the set of resources associated with the PHICH.

In a fourteenth aspect, alone or in combination with any one or more of the first through thirteenth aspects, the enhancement information includes an indication that a UE is to receive an additional PDCCH in at least one symbol of a set of resources associated with a PHICH.

In a fifteenth aspect, in combination with the fourteenth aspect, transmitting the enhanced CAS includes transmitting the additional PDCCH in the at least one symbol of the set of resources associated with the PHICH.

In a sixteenth aspect, alone or in combination with any one or more of the first through fifteenth aspects, the enhancement information includes information that identifies a number of symbols associated with a PDCCH.

In a seventeenth aspect, alone or in combination with any one or more of the first through sixteenth aspects, the enhancement information includes information that identifies a quantity of blind decoding attempts that a UE is to perform in association with receiving a PDCCH in a common search space of the enhanced CAS.

In an eighteenth aspect, alone or in combination with any one or more of the first through seventeenth aspects, the enhancement information includes an indication that a UE is not to monitor at least one legacy PDCCH candidate in a common search space of the enhanced CAS.

In a nineteenth aspect, alone or in combination with any one or more of the first through eighteenth aspects, the enhancement information includes an indication that a UE is to perform a single decoding attempt in a common search space of the enhanced CAS.

In a twentieth aspect, alone or in combination with any one or more of the first through nineteenth aspects, the enhancement information includes an indication of whether a particular CAS enhancement is active in the enhanced CAS.

In a twenty-first aspect, the enhancement information includes an indication that a UE is to skip decoding of a PDCCH.

In a twenty-second aspect, in combination with the twenty-first aspect, the indication includes information that identifies a start symbol of a PDSCH.

In a twenty-third aspect, in combination with any one or more of the twenty-first and twenty-second aspects, the indication includes information that identifies at least one of a number of control symbols associated with skipping the decoding of the PDCCH, a transport block size of a system information block associated with skipping the decoding of the PDCCH, a resource allocation associated with skipping the decoding of the PDCCH, or a subframe associated with skipping the decoding of the PDCCH.

In a twenty-fourth aspect, alone or in combination with any one or more of the first through twenty-third aspects, the enhancement information includes an indication that a UE is to receive an additional CRS in at least one symbol of a set of resources associated with a PHICH.

In a twenty-fifth aspect, in combination with the twenty-fourth aspect, the additional CRS is descrambled based at least in part on a cell identifier or a frame number.

In a twenty-sixth aspect, in combination with any one or more of the twenty-fourth and twenty-fifth aspects, the at least one symbol in which the additional CRS is received is dependent on a cell identifier.

In a twenty-seventh aspect, alone or in combination with any one or more of the first through twenty-sixth aspects, the enhancement information includes an indication that a UE is to receive an additional CRS in one or more resources corresponding to a CRS port that is to be ignored by legacy UEs.

In a twenty-eighth aspect, in combination with the twenty-seventh aspect, the additional CRS is scrambled based at least in part on at least one of a cell identifier, a symbol number, or a frame number.

<FIG> is a block diagram of an example apparatus <NUM> for wireless communication. The apparatus <NUM> may be a UE, or a UE may include the apparatus <NUM>. In some aspects, the apparatus <NUM> includes a reception component <NUM>, a communication manager <NUM>, and a transmission component <NUM>, which may be in communication with one another (for example, via one or more buses). As shown, the apparatus <NUM> may communicate with another apparatus <NUM> (such as a UE, a base station, or another wireless communication device) using the reception component <NUM> and the transmission component <NUM>.

In some aspects, the apparatus <NUM> may be configured to perform one or more operations described herein in connection with <FIG>. Additionally or alternatively, the apparatus <NUM> may be configured to perform one or more processes described herein, such as process <NUM> of <FIG>. In some aspects, the apparatus <NUM> may include one or more components of the UE described above in connection with <FIG>.

The reception component <NUM> may provide received communications to one or more other components of the apparatus <NUM>, such as the communication manager <NUM>. In some aspects, the reception component <NUM> may perform signal processing on the received communications (such as filtering, amplification, demodulation, analog-to-digital conversion, demultiplexing, deinterleaving, de-mapping, equalization, interference cancellation, or decoding, among other examples), and may provide the processed signals to the one or more other components.

In some aspects, the communication manager <NUM> may generate communications and may transmit the generated communications to the transmission component <NUM> for transmission to the apparatus <NUM>. In some aspects, the transmission component <NUM> may be collocated with the reception component <NUM> in a transceiver.

The communication manager <NUM> may receive or may cause the reception component <NUM> to receive a master information block (MIB) including enhancement information associated with an enhanced cell acquisition subframe (CAS) for a cellular broadcast service; and may receive or may cause the reception component <NUM> to receive the enhanced CAS, associated with the cellular broadcast service, based at least in part on the enhancement information associated with the enhanced CAS. In some aspects, the communication manager <NUM> may include a controller/processor, a memory, or a combination thereof, of the UE described above in connection with <FIG>.

In some aspects, the enhancement information includes an indication that the apparatus <NUM> is to monitor an enhanced PDCCH candidate in a common search space of the enhanced CAS, and the communication manager <NUM>, when receiving the enhanced CAS or causing the reception component <NUM> to receive the enhanced CAS, may monitor or may cause the reception component <NUM> to monitor the enhanced PDCCH candidate in association with receiving a PDCCH included in the common search space of the enhanced CAS. The communication manager <NUM> may receive or may cause reception component <NUM> to receive the PDCCH in resources of the common search space of the enhanced CAS based at least in part on monitoring the enhanced PDCCH candidate. In some aspects, the communication manager <NUM> may receive or may cause the reception component <NUM> to combine the PDCCH with another PDCCH included in a common search space of another CAS based at least in part on an indication included in the MIB.

In some aspects, the communication manager <NUM> may include a set of components associated with performing operations described herein. In some aspects, one or more components of the set of components may include or may be implemented within a controller/processor, a memory, or a combination thereof, of the UE described above in connection with <FIG>. Additionally or alternatively, one or more components of the set of components may be implemented at least in part as software stored in a memory. For example, a component (or a portion of a component) may be implemented as instructions or code stored in a non-transitory computer-readable medium and executable by a controller or a processor to perform the functions or operations of the component.

<FIG> is a block diagram of an example apparatus <NUM> for wireless communication. The apparatus <NUM> may be a base station, or a base station may include the apparatus <NUM>. In some aspects, the apparatus <NUM> includes a reception component <NUM>, a communication manager <NUM>, and a transmission component <NUM>, which may be in communication with one another (for example, via one or more buses). As shown, the apparatus <NUM> may communicate with another apparatus <NUM> (such as a UE, a base station, or another wireless communication device) using the reception component <NUM> and the transmission component <NUM>.

In some aspects, the apparatus <NUM> may be configured to perform one or more operations described herein in connection with <FIG>. Additionally or alternatively, the apparatus <NUM> may be configured to perform one or more processes described herein, such as process <NUM> of <FIG>. In some aspects, the apparatus <NUM> may include one or more components of the base station described above in connection with <FIG>.

The reception component <NUM> may provide received communications to one or more other components of the apparatus <NUM>, such as the communication manager <NUM>. In some aspects, the reception component <NUM> may perform signal processing on the received communications (such as filtering, amplification, demodulation, analog-to-digital conversion, demultiplexing, deinterleaving, de-mapping, equalization, interference cancellation, or decoding, among other examples), and may provide the processed signals to the one or more other components. In some aspects, the reception component <NUM> may include one or more antennas, a demodulator, a MIMO detector, a receive processor, a controller/processor, a memory, or a combination thereof, of the base station described above in connection with <FIG>.

In some aspects, the communication manager <NUM> may generate communications and may transmit the generated communications to the transmission component <NUM> for transmission to the apparatus <NUM>. In some aspects, the transmission component <NUM> may include one or more antennas, a modulator, a transmit MIMO processor, a transmit processor, a controller/processor, a memory, or a combination thereof, of the base station described above in connection with <FIG>. In some aspects, the transmission component <NUM> may be collocated with the reception component <NUM> in a transceiver.

The communication manager <NUM> may or may cause transmission component <NUM> to transmit a master information block (MIB) including enhancement information associated with an enhanced cell acquisition subframe (CAS) for a cellular broadcast service; and may transmit or may cause transmission component <NUM> to transmit the enhanced CAS, associated with the cellular broadcast service, based at least in part on the enhancement information associated with the enhanced CAS. In some aspects, the communication manager <NUM> may include a controller/processor, a memory, a scheduler, a communication unit, or a combination thereof, of the base station described above in connection with <FIG>.

In some aspects, the enhancement information includes an indication that a UE is to monitor an enhanced PDCCH candidate in a common search space of the enhanced CAS, and the communication manager <NUM>, when transmitting the enhanced CAS or causing the transmission component <NUM> to transmit the enhanced CAS, may generate or cause the transmission component <NUM> to generate the PDCCH to be transmitted in resources of the enhanced PDCCH candidate in the common search space of the enhanced CAS associated with the cellular broadcast service. The communication manager <NUM> may transmit or may cause transmission component <NUM> to transmit the PDCCH in the resources of the enhanced PDCCH candidate in the common search space of the enhanced CAS associated with the cellular broadcast service. In some aspects, the communication manager <NUM> may encode or may cause transmission component <NUM> to encode control information, included in the PDCCH, such that the control information is decodable by a legacy user equipment configured to monitor the legacy PDCCH candidate in the common search space of the enhanced CAS.

In some aspects, the communication manager <NUM> may include a set of components. In some aspects, one or more components of the set of components may include or may be implemented within a controller/processor, a memory, a scheduler, a communication unit, or a combination thereof, of the base station described above in connection with <FIG>. Additionally or alternatively, one or more components of the set of components may be implemented at least in part as software stored in a memory. For example, a component (or a portion of a component) may be implemented as instructions or code stored in a non-transitory computer-readable medium and executable by a controller or a processor to perform the functions or operations of the component.

As used herein, satisfying a threshold may refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, or the like, or combinations thereof.

It will be apparent that systems or methods described herein may be implemented in different forms of hardware, firmware, or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems or methods is not limiting of the aspects. Thus, the operation and behavior of the systems or methods were described herein without reference to specific software code-it being understood that software and hardware can be designed to implement the systems or methods based, at least in part, on the description herein.

Claim 1:
A method of wireless communication performed by a user equipment, UE (<NUM>), comprising:
receiving (<NUM>) a master information block, MIB, including enhancement information associated with an enhanced cell acquisition subframe, CAS, for a cellular broadcast service, wherein the enhancement information includes an indication that the UE (<NUM>) is to monitor an enhanced physical downlink control channel, PDCCH, candidate in a common search space of the enhanced CAS; and
receiving (<NUM>) the enhanced CAS, associated with the cellular broadcast service, based at least in part on the enhancement information associated with the enhanced CAS.