Patent Description:
A wireless multiple-access communications system may include a number of base stations (BSs), each simultaneously supporting communications for multiple communication devices, which may be otherwise known as user equipment (UE).

To meet the growing demands for expanded mobile broadband connectivity, wireless communication technologies are advancing from the long term evolution (LTE) technology to a next generation new radio (NR) technology, which may be referred to as <NUM>th Generation (<NUM>). For example, the NR is designed to provide a lower latency, a higher bandwidth or a higher throughput, and a higher reliability than the LTE. The NR is designed to operate over a wide array of spectrum bands, for example, from low-frequency bands below about <NUM> gigahertz (GHz) and mid-frequency bands from about <NUM> to about <NUM>, to highfrequency bands such as millimeter wave (mmWave) bands. The NR is also designed to operate across different spectrum types, including licensed spectrum, unlicensed and shared spectrum. Spectrum sharing enables operators to opportunistically aggregate spectrums to dynamically support high-bandwidth services. Spectrum sharing can extend the benefit of NR technologies to operating entities that may not have access to a licensed spectrum.

As wireless communications evolve, so does signaling, such as radio resource control (RRC) signaling, that the BSs and UEs use to communicate with each other. As the signaling evolves, there is an expectation that the new signaling that the BS transmits to the new UEs be backward compatible with the legacy signaling that the BS transmits to the legacy UEs.

<CIT> provides a method and device for transmitting, receiving configuration information of a low latency service. The method comprises: a site configuring sub-frames of low latency service, and transmitting the configuration information of the sub-frames of low latency service; the configuration information comprising: the site configuring Multimedia Broadcast multicast service Single Frequency Network (MBSFN) sub-frames used for low latency service transmission and/or configuring non-MBSFN sub-frames used for low latency service transmission, wherein the MBSFN sub-frames or the non-MBSFN sub-frames used for transmitting low latency service using a short Transmission Time Interval (TTI) to transmit data.

The scope of protection is defined by the independent claims.

This disclosure relates generally to wireless communications systems, also referred to as wireless communications networks. In various embodiments, the techniques and apparatus may be used for wireless communication networks such as code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, single-carrier FDMA (SC-FDMA) networks, LTE networks, Global System for Mobile Communications (GSM) networks, <NUM>th Generation (<NUM>) or new radio (NR) networks, as well as other communications networks. As described herein, the terms "networks" and "systems" may be used interchangeably.

An OFDMA network may implement a radio technology such as evolved UTRA (E-UTRA), Institute of Electrical and Electronics Engineers (IEEE) <NUM>, IEEE <NUM>, IEEE <NUM>, flash-OFDM (orthogonal frequency division multiplexing) and the like. UTRA, E-UTRA, and GSM are part of universal mobile telecommunication system (UMTS). 3GPP long term evolution (LTE) is a 3GPP project which was aimed at improving the UMTS mobile phone standard.

In particular, <NUM> networks contemplate diverse deployments, diverse spectrum, and diverse services and devices that may be implemented using an OFDM-based unified, air interface. In order to achieve these goals, further enhancements to LTE and LTE-A are considered in addition to development of the new radio technology for <NUM> NR networks. The <NUM> NR will be capable of scaling to provide coverage (<NUM>) to a massive Internet of things (IoTs) with a ULtra-high density (e.g., ~<NUM> nodes/km<NUM>), ultra-low complexity (e.g., ~<NUM> of bits/sec), ultra-low energy (e.g., ~<NUM>+ years of battery life), and deep coverage with the capability to reach challenging locations; (<NUM>) including mission-critical control with strong security to safeguard sensitive personal, financial, or classified information, ultra-high reliability (e.g., ~<NUM>% reliability), ultra-low latency (e.g., ~ <NUM>), and users with wide ranges of mobility or lack thereof; and (<NUM>) with enhanced mobile broadband including extreme high capacity (e.g., ~ <NUM> Tbps/km<NUM>), extreme data rates (e.g., multi-Gbps rate, <NUM>+ Mbps user experienced rates), and deep awareness with advanced discovery and optimizations.

The <NUM> NR may be implemented to use optimized OFDM-based waveforms with scalable numerology and transmission time interval (TTI); having a common, flexible framework to efficiently multiplex services and features with a dynamic, low-latency time division duplex (TDD)/frequency division duplex (FDD) design; and with advanced wireless technologies, such as massive multiple input, multiple output (MIMO), robust millimeter wave (mmWave) transmissions, advanced channel coding, and device-centric mobility. Scalability of the numerology in <NUM> NR, with scaling of subcarrier spacing, may efficiently address operating diverse services across diverse spectrum and diverse deployments. For example, in various outdoor and macro coverage deployments of less than <NUM> FDD/TDD implementations, subcarrier spacing may occur with <NUM>, for example over <NUM>, <NUM>, <NUM>, and the like bandwidth (BW). For other various outdoor and small cell coverage deployments of TDD greater than <NUM>, subcarrier spacing may occur with <NUM> over <NUM>/<NUM> BW. For other various indoor wideband implementations, using a TDD over the unlicensed portion of the <NUM> band, the subcarrier spacing may occur with <NUM> over a <NUM> BW. Finally, for various deployments transmitting with mmWave components at a TDD of <NUM>, subcarrier spacing may occur with <NUM> over a <NUM> BW.

<NUM> NR also contemplates a self-contained integrated subframe design with UL/downlink scheduling information, data, and acknowledgement in the same subframe. The self-contained integrated subframe supports communications in unlicensed or contention-based shared spectrum, adaptive UL/downlink that may be flexibly configured on a per-cell basis to dynamically switch between UL and downlink to meet the current traffic needs.

As wireless communications evolve, so does the control signaling, such as radio resource control (RRC) signaling between a base station (BS) and user equipments (UEs). Because certain fields in the signal configuration are required, these fields must be present in different versions of the control signaling for backward compatibility. At the same time, the new control signaling that is received by the new UEs should not be able to activate or enable the features in the older or legacy UEs. Similarly, the legacy control signaling that is received by the legacy or old UEs should not be able to activate features in the new UEs. Example features may be different sub-carrier spacing for sub-carriers that are used by the legacy and new multimedia broadcast multicast service (MBMS). When the new signaling activates the features in the legacy UE or vice versa, the UEs may exhibit unexpected behavior and generate unintended errors. The aspects below describe techniques for configuring new control signaling for new UEs with backward compatibility for the legacy UEs.

<FIG> illustrates a wireless communication network <NUM> according to some aspects of the present disclosure. The network <NUM> may be a <NUM> network. The network <NUM> includes a number of base stations (BSs) <NUM> (individually labeled as 105a, 105b, 105c, 105d, 105e, and 105f) and other network entities. A BS <NUM> may be a station that communicates with UEs <NUM> and may also be referred to as an evolved node B (eNB), a next generation eNB (gNB), an access point, and the like. Each BS <NUM> may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to this particular geographic coverage area of a BS <NUM> and/or a BS subsystem serving the coverage area, depending on the context in which the term is used.

The UEs <NUM> are dispersed throughout the wireless network <NUM>, and each UE <NUM> may be stationary or mobile. A UE <NUM> may also be referred to as a terminal, a mobile station, a subscriber unit, a station, or the like. A UE <NUM> may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a wireless local loop (WLL) station, or the like. In one aspect, a UE <NUM> may be a device that includes a Universal Integrated Circuit Card (UICC). In another aspect, a UE may be a device that does not include a UICC. In some aspects, the UEs <NUM> that do not include UICCs may also be referred to as IoT devices or internet of everything (IoE) devices. The UEs 115a-115d are examples of mobile smart phone-type devices accessing network <NUM>. A UE <NUM> may also be a machine specifically configured for connected communication, including machine type communication (MTC), enhanced MTC (eMTC), narrowband IoT (NB-IoT) and the like. The UEs 115e-<NUM> are examples of various machines configured for communication that access the network <NUM>. The UEs 115i-<NUM> are examples of vehicles equipped with wireless communication devices configured for communication that access the network <NUM>. A UE <NUM> may be able to communicate with any type of the BSs, whether macro BS, small cell, or the like. In <FIG>, a lightning bolt (e.g., communication links) indicates wireless transmissions between a UE <NUM> and a serving BS <NUM>, which is a BS designated to serve the UE <NUM> on the downlink (DL) and/or uplink (UL), desired transmission between BSs <NUM>, backhaul transmissions between BSs, or sidelink transmissions between UEs <NUM>.

The macro BS 105d may perform backhaul communications with the BSs 105a-105c, as well as small cell, the BS 105f The macro BS 105d may also transmits multicast services which are subscribed to and received by the UEs 115c and 115d.

The BSs <NUM> may also communicate with a core network. The core network may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. At least some of the BSs <NUM> (e.g., which may be an example of a gNB or an access node controller (ANC)) may interface with the core network through backhaul links (e.g., NG-C, NG-U, etc.) and may perform radio configuration and scheduling for communication with the UEs <NUM>. In various examples, the BSs <NUM> may communicate, either directly or indirectly (e.g., through core network), with each other over backhaul links (e.g., X1, X2, etc.), which may be wired or wireless communication links.

The network <NUM> may also support mission critical communications with ultra-reliable and redundant links for mission critical devices, such as the UE 115e, which may be a drone. Redundant communication links with the UE 115e may include links from the macro BSs 105d and 105e, as well as links from the small cell BS 105f Other machine type devices, such as the UE 115f (e.g., a thermometer), the UE <NUM> (e.g., smart meter), and UE <NUM> (e.g., wearable device) may communicate through the network <NUM> either directly with BSs, such as the small cell BS 105f, and the macro BS 105e, or in multi-step-size configurations by communicating with another user device which relays its information to the network, such as the UE 115f communicating temperature measurement information to the smart meter, the UE <NUM>, which is then reported to the network through the small cell BS 105f The network <NUM> may also provide additional network efficiency through dynamic, low-latency TDD/FDD communications, such asV2V (vehicle-to-vehicle), V2X (vehicle-to-everything), C-V2X (cellular-V2X) communications between a UE 115i, 115j, or <NUM> and other UEs <NUM>, and/or vehicle-to-infrastructure (V2I) communications between a UE 115i, 115j, or <NUM> and a BS <NUM>.

In some implementations, the network <NUM> utilizes OFDM-based waveforms for communications. An OFDM-based system may partition the system BW into multiple (K) orthogonal subcarriers, which are also commonly referred to as subcarriers, tones, bins, or the like. Each subcarrier may be modulated with data. In some instances, the subcarrier spacing between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may be dependent on the system BW. The system BW may also be partitioned into sub-bands. In other instances, the subcarrier spacing and/or the duration of TTIs may be scalable.

In some aspects, the BSs <NUM> can assign or schedule transmission resources (e.g., in the form of time-frequency resource blocks (RB)) for downlink (DL) and uplink (UL) transmissions in the network <NUM>. DL refers to the transmission direction from a BS <NUM> to a UE <NUM>, whereas UL refers to the transmission direction from a UE <NUM> to a BS <NUM>. The communication can be in the form of radio frames. A radio frame may be divided into a plurality of subframes or slots, for example, about <NUM>. Each slot may be further divided into mini-slots. In a FDD mode, simultaneous UL and DL transmissions may occur in different frequency bands. For example, each subframe includes a UL subframe in a UL frequency band and a DL subframe in a DL frequency band. In a TDD mode, UL and DL transmissions occur at different time periods using the same frequency band. For example, a subset of the subframes (e.g., DL subframes) in a radio frame may be used for DL transmissions and another subset of the subframes (e.g., UL subframes) in the radio frame may be used for UL transmissions.

The DL subframes and the UL subframes can be further divided into several regions. For example, each DL or UL subframe may have pre-defined regions for transmissions of reference signals, control information, and data. Reference signals are predetermined signals that facilitate the communications between the BSs <NUM> and the UEs <NUM>. For example, a reference signal can have a particular pilot pattern or structure, where pilot tones may span across an operational BW or frequency band, each positioned at a pre-defined time and a pre-defined frequency. For example, a BS <NUM> may transmit cell specific reference signals (CRSs) and/or channel state information -reference signals (CSI-RSs) to enable a UE <NUM> to estimate a DL channel. Similarly, a UE <NUM> may transmit sounding reference signals (SRSs) to enable a BS <NUM> to estimate a UL channel. Control information may include resource assignments and protocol controls. Data may include protocol data and/or operational data. In some aspects, the BSs <NUM> and the UEs <NUM> may communicate using self-contained subframes. A self-contained subframe may include a portion for DL communication and a portion for UL communication. A self-contained subframe can be DL-centric or UL-centric. A DL-centric subframe may include a longer duration for DL communication than for UL communication. A UL-centric subframe may include a longer duration for UL communication than for UL communication.

In some aspects, the network <NUM> may be an NR network deployed over a licensed spectrum. The BSs <NUM> can transmit synchronization signals (e.g., including a primary synchronization signal (PSS) and a secondary synchronization signal (SSS)) in the network <NUM> to facilitate synchronization. The BSs <NUM> can broadcast system information associated with the network <NUM> (e.g., including a master information block (MIB), remaining system information (RMSI), and other system information (OSI)) to facilitate initial network access. In some instances, the BSs <NUM> may broadcast the PSS, the SSS, and/or the MIB in the form of synchronization signal block (SSBs) over a physical broadcast channel (PBCH) and may broadcast the RMSI and/or the OSI over a physical downlink shared channel (PDSCH).

In some aspects, a UE <NUM> attempting to access the network <NUM> may perform an initial cell search by detecting a PSS from a BS <NUM>. The PSS may enable synchronization of period timing and may indicate a physical layer identity value. The UE <NUM> may then receive a SSS. The SSS may enable radio frame synchronization, and may provide a cell identity value, which may be combined with the physical layer identity value to identify the cell. The PSS and the SSS may be located in a central portion of a carrier or any suitable frequencies within the carrier.

After receiving the PSS and SSS, the UE <NUM> may receive a MIB. The MIB may include system information for initial network access and scheduling information for RMSI and/or OSI. After decoding the MIB, the UE <NUM> may receive RMSI and/or OSI. The RMSI and/or OSI may include radio resource control (RRC) information related to random access channel (RACH) procedures, paging, control resource set (CORESET) for physical downlink control channel (PDCCH) monitoring physical UL control channel (PUCCH), physical UL shared channel (PUSCH), power control, and SRS.

After obtaining the MIB, the RMSI and/or the OSI, the UE <NUM> can perform a random access procedure to establish a connection with the BS <NUM>. In some examples, the random access procedure may be a four-step random access procedure. For example, the UE <NUM> may transmit a random access preamble and the BS <NUM> may respond with a random access response. The random access response (RAR) may include a detected random access preamble identifier (ID) corresponding to the random access preamble, timing advance (TA) information, a UL grant, a temporary cell-radio network temporary identifier (C-RNTI), and/or a backoff indicator. Upon receiving the random access response, the UE <NUM> may transmit a connection request to the BS <NUM> and the BS <NUM> may respond with a connection response. The connection response may indicate a contention resolution. In some examples, the random access preamble, the RAR, the connection request, and the connection response can be referred to as message <NUM> (MSG1), message <NUM> (MSG2), message <NUM> (MSG3), and message <NUM> (MSG4), respectively. In some examples, the random access procedure may be a two-step random access procedure, where the UE <NUM> may transmit a random access preamble and a connection request in a single transmission and the BS <NUM> may respond by transmitting a random access response and a connection response in a single transmission.

After establishing a connection, the UE <NUM> and the BS <NUM> can enter a normal operation stage, where operational data may be exchanged. For example, the BS <NUM> may schedule the UE <NUM> for UL and/or DL communications. The BS <NUM> may transmit UL and/or DL scheduling grants to the UE <NUM> via a PDCCH. The scheduling grants may be transmitted in the form of DL control information (DCI). The BS <NUM> may transmit a DL communication signal (e.g., carrying data) to the UE <NUM> via a PDSCH according to a DL scheduling grant. The UE <NUM> may transmit a UL communication signal to the BS <NUM> via a PUSCH and/or PUCCH according to a UL scheduling grant.

In some aspects, the BS <NUM> may communicate with a UE <NUM> using HARQ (hybrid automatic repeat request) techniques to improve communication reliability, for example, to provide a URLLC (ultra-reliable low-latency communication) service. The BS <NUM> may schedule a UE <NUM> for a PDSCH communication by transmitting a DL grant in a PDCCH. The BS <NUM> may transmit a DL data packet to the UE <NUM> according to the schedule in the PDSCH. The DL data packet may be transmitted in the form of a transport block (TB). If the UE <NUM> receives the DL data packet successfully, the UE <NUM> may transmit a HARQ ACK (acknowledgment) to the BS <NUM>. Conversely, if the UE <NUM> fails to receive the DL transmission successfully, the UE <NUM> may transmit a HARQ NACK (negative acknowledgement) to the BS <NUM>. Upon receiving a HARQ NACK from the UE <NUM>, the BS <NUM> may retransmit the DL data packet to the UE <NUM>. The retransmission may include the same coded version of DL data as the initial transmission. Alternatively, the retransmission may include a different coded version of the DL data than the initial transmission. The UE <NUM> may apply soft-combining to combine the encoded data received from the initial transmission and the retransmission for decoding. The BS <NUM> and the UE <NUM> may also apply HARQ for UL communications using substantially similar mechanisms as the DL HARQ.

In some aspects, the network <NUM> may operate over a system BW or a component carrier (CC) BW. The network <NUM> may partition the system BW into multiple BWPs (e.g., portions). A BS <NUM> may dynamically assign a UE <NUM> to operate over a certain BWP (e.g., a certain portion of the system BW). The assigned BWP may be referred to as the active BWP. The UE <NUM> may monitor the active BWP for signaling information from the BS <NUM>. The BS <NUM> may schedule the UE <NUM> for UL or DL communications in the active BWP. In some aspects, a BS <NUM> may assign a pair of BWPs within the CC to a UE <NUM> for UL and DL communications. For example, the BWP pair may include one BWP for UL communications and one BWP for DL communications.

In some aspects, the network <NUM> may operate over a shared channel, which may include shared frequency bands or unlicensed frequency bands. For example, the network <NUM> may be an NR-unlicensed (NR-U) network operating over an unlicensed frequency band. In such an aspect, the BSs <NUM> and the UEs <NUM> may be operated by multiple network operating entities. To avoid collisions, the BSs <NUM> and the UEs <NUM> may employ a listen-before-talk (LBT) procedure to monitor for transmission opportunities (TXOPs) in the shared channel. For example, a transmitting node (e.g., a BS <NUM> or a UE <NUM>) may perform an LBT prior to transmitting in the channel. When the LBT passes, the transmitting node may proceed with the transmission. When the LBT fails, the transmitting node may refrain from transmitting in the channel. In an example, the LBT may be based on energy detection. For example, the LBT results in a pass when signal energy measured from the channel is below a threshold. Conversely, the LBT results in a failure when signal energy measured from the channel exceeds the threshold. In another example, the LBT may be based on signal detection. For example, the LBT results in a pass when a channel reservation signal (e.g., a predetermined preamble signal) is not detected in the channel. A TXOP may also be referred to as channel occupancy time (COT).

In some aspects, network <NUM> may communicate with UEs <NUM> that communicate using different versions of the control signaling, such as radio resource control (RRC) signaling. The UEs <NUM> that receive the new or latest RRC signaling from the BS <NUM> may be referred to as new UEs 115n and UEs <NUM> that receive an older or legacy RRC signaling may be referred to as old or legacy UEs <NUM>. In some cases, the RRC signaling may include control information for configuring the multimedia broadcast multicast service (MBMS). The MBMS is a service that transmits data packets to multiple users at the same time and that is used for efficient delivery of broadcast or multicast services. Although the aspects below are discussed with respect to configuring and processing backward compatible new and legacy RRC signaling that provides control information for the MBMS, the aspects are also applicable to other types of control signaling. Further, it is desirable for the new signaling to enable the new MBMS without enabling the features of the legacy MBMS and vice versa.

As discussed above, the UEs <NUM> may receive RRC signals from BS <NUM>. The RRC signals may carry control information related to the MBMS. The MBMS control information may be provided on the multicast control channel or MCCH. The BS <NUM> may use one MCCH per multicast-broadcast single-frequency network (MBSFN) area. In some instances, UE <NUM> may receive an MBSFN-AreaInfoList information element from BS <NUM> that contains information that UE <NUM> requires to acquire from the MBMS control information associated with one or more MBSFN areas. The AreaInfoList information element may be included in the RRC signals.

<FIG> is a diagram <NUM> illustrating a base station transmitting the RRC signaling to a user equipment, according to aspects of the disclosure. As illustrated in diagram, UE <NUM> makes an RRC connection request <NUM> to BS <NUM>. In response to the RRC connection request <NUM>, BS <NUM> may transmit an RRC connection setup message <NUM> to UE <NUM>. Once UE <NUM> receives and processes the RRC connection setup message <NUM>, UE <NUM> enters into the RRC connection mode and transmits the RRC connection established message <NUM> to BS <NUM>. Subsequent to the RRC connection established message <NUM>, UE <NUM> may receive RRC signaling <NUM> from BS <NUM>.

As MBMSs evolve, so does the RRC signaling that BS <NUM> transmits to UEs <NUM> and that UEs <NUM> use to set-up and configure the MBMSs. As part of the new signaling configuration for the RRC signaling, the BS <NUM> may specify new numerologies for the physical multicast channel (PMCH) which includes enhanced physical channels and signals in the cell-acquisition subframe (CAS). Accordingly, the new numerologies for the PMCH may have different sub-carrier spacing than the PMCH numerologies in the legacy MBMS. There is an expectation, however, for the new signaling configuration to be backward compatible and to be added to the RRC signaling in a way that the new signaling configuration does not disrupt the legacy RRC signaling for the legacy physical channels. This is because the new signaling may be used by the new UEs 115n that may set up the new MBMS while the legacy signaling may be used by the legacy UEs <NUM> that may set up the legacy MBMS. Thus, it is desirable for BS <NUM> to generate the RRC signals that include the new signaling configuration for the new UEs 115n and legacy signaling configuration for the legacy UEs <NUM>. Further, it is desirable for the new UEs 115n to be backwards compatible and be able to process the RRC signaling that includes the new signaling configurations for enhanced physical channels for MBMS without enabling the legacy features in the MBMS. Correspondingly, there is an expectation for the legacy UEs <NUM> configured for legacy RRC signaling to be able to identify the RRC signaling that includes the legacy signaling configuration and also identify and ignore the RRC signaling that includes the new signaling configuration. This is because the new MBMS with new sub-carrier spacing may not work with legacy UEs <NUM>.

The signaling configuration carried by the RRC signaling may have mandatory or non-optional fields. The mandatory or non-optional fields may carry MBMS control information. This control information may be common to different versions of the MBMS. For the RRC signaling to be backwards compatible, these fields exist in the new and legacy signaling configurations. However, simply leaving the mandatory fields and adding new fields to the new signaling configuration may not solve the backward compatibility issue for signaling configurations between the legacy UEs <NUM> and new UEs 115n. This is because the fields in the RRC signaling that are specific to the new UE 115n can be processed by the legacy UE <NUM>, and the legacy UE <NUM> may assume MBMS functionality that is either erroneous or incompatible with the legacy UE <NUM>.

To make the new signaling configuration backward compatible, BS <NUM> may use a combination of a legacy configuration and a new configuration in the new signaling configuration. For example, the BS <NUM> may identify a non-optional field in the legacy configuration which the legacy UE <NUM> may decode without an error. However, the BS <NUM> may include a value in the non-optional field that may indicate a configuration error to the legacy UE <NUM> that causes the legacy UE <NUM> to ignore the new signaling configuration. The value that indicates an error is a value that has all bits set to zero, a value that is outside of an expected value range. In this way, when the legacy UE <NUM> receives the RRC signaling that includes the legacy configuration and the new configuration, the legacy UE <NUM> may decode the non-optional field and based on its value determine that the RRC signaling is to be ignored. Thus, if the legacy UE <NUM> receives the RRC signaling that includes the set-up for the new MBMS, the legacy UE <NUM> may not set up or configure the MBMS service.

In addition to the non-optional field in the legacy configuration, the BS <NUM> may also create a separate new configuration for the new UE 115n and add the new configuration to the new signaling configuration included in the RRC signaling. Thus, the new signaling configuration includes a legacy configuration with a non-optional field and a new configuration. While including the non-optional field in the signaling configuration causes the signaling configuration to be in a format that is backward compatible with the legacy UE <NUM>, when the new UE 115n receives the new signaling configuration, the value in the non-optional field indicates to UE 115n to decode the new signaling configuration. The BS <NUM> encodes the non-optional field with a value that indicates that the new UE 115n may process the new configuration included in the new signaling configuration while the legacy UE <NUM> may ignore the new signaling configuration. In this way, when the legacy UE <NUM> receives the new signaling configuration, the legacy UE <NUM> may decode the non-optional field with a value that indicates that the configuration is to be ignored and does not decode the new configuration. However, when the new UE 115n receives the new signaling configuration, the new UE 115n may decode both the non-optional field in the legacy configuration and the new configuration. If the new signaling configuration includes a set-up for a new MBMS service, the new UE 115n may set up the new MBMS service upon decoding the new signaling configuration.

The aspects above may be further illustrated using an MBSFN-AreaInfoList information element (IE) that BS <NUM> includes in the RRC signaling to set up the MBMS with the UE <NUM>. The MBSFN-AreaInfoList IE contains information required to acquire the MBMS control information associated with one or more MBSFN areas. The BS <NUM> may generate the MBSFN-AreaInfoList IE as part of an RRC signal broadcast transmission to UEs <NUM>. Both new UEs 115n and legacy UEs <NUM> may receive the broadcast transmission with the MBSFN-AreaInfoList IE included in the RRC signaling.

<FIG> is a diagram 300A that illustrates a legacy MBSFN-AreaInfoList information element according to aspects of the disclosure. The MBSFN-AreaInfoList IE in <FIG> is a MBSFN-AreaInfoList-r9 IE <NUM> which includes a legacy MBSFN-AreaInfoList-r9 configuration <NUM> that is associated with a software release <NUM>. The MBSFN-AreaInfoList-r9 configuration <NUM> may be referred to as the legacy MBMS configuration. The MBSFN-AreaInfoList-r9 configuration <NUM> is a mandatory configuration and must include a number of non-zero elements, where each element is defined by a MBSFN-AreaInfo-r9 configuration <NUM>. The MBSFN-AreaInfo-r9 configuration <NUM> includes a mandatory or non-optional sf-AllocInfo-r9 field <NUM>. The sf-AllocInfo-r9 field <NUM> may specify the subframes of the radio frame that may carry the MCCH. In particular, the sf-AllocInfo-r9 field <NUM> may indicate the subframes of the radio frames indicated by a mcch-RepetitionPeriod field <NUM> and a mcch-Offset-r9 field <NUM>. The sf-AllocInfo-r9 field <NUM> may include one or more bits that can be configured with "<NUM>" or "<NUM>" values. The value "<NUM>" indicates that the corresponding subframe is allocated. In one aspect of the disclosure, all bits in sf-AllocInfo-r9 field <NUM> may be set to zero. In this case, the corresponding MBSFN area is considered to be not configured and may not carry the MCCH.

Because MBSFN-AreaInfoList-r9 configuration <NUM> is mandatory or non-optional, the MBSFN-ArealnfoList-r9 configuration <NUM> may be included in the new signaling configuration for the MBMS service. An example new signaling configuration may be a release <NUM>, where the release <NUM> is a new software version of the older or legacy release <NUM>. To make the MBSFN-AreaInfoList-r9 configuration <NUM> backward compatible in the new signaling configuration for the MBMS service, the BS <NUM> may include one or more elements MBSFN-AreaInfo-r9 configuration <NUM> and, in each included element, set all bits in the sf-AllocInfo-r9 field <NUM> to zero. In this case, the sf-AllocInfo-r9 field <NUM> is an indicator that indicates whether the legacy signaling configuration or a new signaling configuration may be used. When all bits in sf-AllocInfo-r9 field <NUM> are set to zero, the legacy UE <NUM> may decode the st-AllocInfo-r9 field <NUM> without an error, but based on the zero values in all bit locations may determine that the configuration should not be used because the MBSFN area is not configured. Thus, the legacy UE <NUM> may not receive the MBMS service as there is no subframe for MCCH. In this way, the legacy UE <NUM> receiving the MBSFN-AreaInfoList-r9 IE <NUM> as part of the new signaling configuration may process the MBSFN-AreaInfoList-r9 IE <NUM> but may not receive the MBMS service when all bits in st-AllocInfo-r9 field <NUM> are set to zero. Accordingly, <FIG> illustrates that MBSFN-AreaInfoList-r9 configuration <NUM> is a legacy configuration and sf-AllocInfo-r9 field <NUM> is a non-optional field which may indicate to the legacy UE <NUM> to not set up the MBMS.

To determine a new signaling configuration for new UE 115n, BS <NUM> in addition to setting all bits in the sf-AllocInfo-r9 field <NUM> to zero in the MBSFN-AreaInfoList-r9 configuration <NUM>, may also define a new configuration, such as MBSFN-AreaInfoList-r16 configuration. MBSFN-AreaInfoList-r16 configuration may include new signaling and may be decoded by the new UEs 115n, but ignored by legacy UE <NUM>. <FIG> is a diagram 300B that illustrates an MBSFN-AreaInfoList information element with a legacy MBSFN-AreaInfoList-r9 configuration and a new MBSFN-AreaInfoList-r16 configuration, according to aspects of the disclosure. In <FIG> the new MBMS configuration may include the MBSFN-AreaInfoList-r9 configuration <NUM> and a new MBSFN-AreaInfoList-r16 configuration <NUM>. The MBSFN-AreaInfoList-r9 configuration <NUM> is a legacy configuration and MBSFN-AreaInfoList-r16 <NUM> is a new configuration. The MBSFN-AreaInfoList-r16 configuration <NUM> may include sf-AllocInfo-r16 field <NUM> and subcarrierSpacingTimeSeparationMBMS-r16 field <NUM>. Notably the names of the fields <NUM> and <NUM> are exemplary for purpose of the aspects described herein. The MBSFN-AreaInfoList-r16 configuration <NUM> may indicate the subframes of the radio frames indicated by the mcch-RepetitionPeriod-r16 field <NUM> and the mcch-Offset-r16 filed <NUM> that may carry MCCH, where value "<NUM>" indicates that the corresponding subframe is allocated. Further, in one example, the first or leftmost bit may define the allocation for subframe #<NUM> of the radio frame indicated by the mcch-RepetitioPeriod-r16 field <NUM> and mcch-Offset-r16 field <NUM>, the second or the second leftmost bit may define allocation for subframe #<NUM> of the radio subframe, and so on. The allocation of subframes may also be defined in other ways, e.g. the last or rightmost bit may define the allocation for subframe #<NUM>, etc. The subcarrierSpacingTimeSeparationMBMS-r16 field <NUM> or a similar field may indicate for the MBSFN subframes, subcarrier spacing and for the <NUM> subcarrier spacing additionally indicate the staggering length for the MBSFN-RS (MBSFN reference signal) associated with the PMCH. Further, the value khz-2dot5 may refer to <NUM> subcarrier spacing, khz-<NUM>-slot2 refers to the <NUM> subcarrier spacing with staggering length of <NUM> slots and khz-<NUM>-slot4 refers to the <NUM> subcarrier spacing with staggering length of <NUM> slots. Alternatively, separate fields may be defined to indicate the subcarrier spacing and staggering length for the MBSFN-RS associated with the PMCH.

The BS <NUM> may encode the MBSFN-AreaInfoList-r9 configuration <NUM> for setting up the MBMS on the legacy UE <NUM>. In this case, BS <NUM> may set bits in sf-AllocInfo-r9 field <NUM> to values that may be processed by the legacy UE <NUM>, such as bits that are a combination of zeros and ones, or all ones.

BS <NUM> may also encode MBSFN-AreaInfoList-r9 configuration <NUM> and MBSFN-AreaInfoList-r16 configuration <NUM> for setting up the MBMS for the new UE 115n. When BS <NUM> encodes MBSFN-AreaInfoList-r16 configuration <NUM>, BS <NUM> may also encode MBSFN-AreaInfoList-r9 configuration <NUM> and set all bits in sf-AllocInfo-r9 field <NUM> to zero. In this way, when the legacy UE <NUM> receives the new signaling configuration that includes MBSFN-AreaInfoList-r9 configuration <NUM> and MBSFN-AreaInfoList-r16 configuration <NUM>, the legacy UE <NUM> may receive, properly decode, and determine that all bits in sf-AllocInfo-r9 field <NUM> are set to zero. In this case, legacy UE <NUM> may ignore the MBSFN-AreaInfoList-r9 configuration <NUM> and MBSFN-AreaInfoList-r16 configuration <NUM> because the non-optional field sf-AllocInfo-r9 field <NUM> indicates that all bits are set to zero. However, when the new UE 115n receives the new signaling configuration that includes MBSFN-AreaInfoList-r9 configuration <NUM> and MBSFN-AreaInfoList-r16 configuration <NUM>, the new UE 115n may properly decode the non-optional field sf-AllocInfo-r9 field <NUM> that indicates that all bits are set to zero. In this case, the new UE <NUM> may use the MBSFN-AreaInfoList-r16 configuration <NUM> to set up the MBMS.

In some aspects, BS <NUM> may encode the encode MBSFN-AreaInfoList-r9 configuration <NUM> and MBSFN-AreaInfoList-r16 configuration <NUM> and also set bits in sf-AllocInfo-r9 field <NUM> to values that are a combination of zeros and ones, or all ones. In this case, the legacy UE <NUM> may receive, properly decode, and process the legacy signaling configuration included in MBSFN-AreaInfoList-r9 configuration because the values in the sf-AllocInfo-r9 field indicate a valid legacy signaling configuration. The new UE 115n may also receive and properly decode the sf-AllocInfo-r9 field. Because the sf-AllocInfo-r9 field indicates a valid legacy signaling and the new UE 115n receives both MBSFN-AreaInfoList-r9 configuration <NUM> and MBSFN-AreaInfoList-r16 configuration <NUM>, the new UE 115n may select whether to use the legacy signaling configuration included in MBSFN-AreaInfoList-r9 configuration <NUM> or the new signaling configuration included in MBSFN-AreaInfoList-r16 configuration <NUM>.

As discussed in <FIG>, the BS <NUM> may set all bits of sf-AllocInfo-r9 field <NUM> to zero in the new signaling configuration to indicate to the legacy UE <NUM> to ignore the new signaling configuration. BS <NUM>, however, is not limited to this implementation, and may also use other fields and values to indicate a new signaling configuration to the legacy UE <NUM>. In another example, BS <NUM> may encode a non-optional field in the MBSFN-AreaInfoList-r9 configuration <NUM> with a value that is outside of a specified value range or an unexpected value as an indication to use the new signaling configuration. The unexpected values may be values that are not defined to be associated with MBSFN-AreaInfoList-r9 configuration <NUM>. When the value of the field is outside of the specified range or is unexpected, the legacy UE <NUM> may also correctly decode the field, determine that the field is set to a wrong value, and ignore the new signaling configuration. On the other hand, the new UE 115n may encounter the non-optional field in the MBSFN-AreaInfoList-r9 configuration <NUM> and continue to decode the new signaling configuration, e.g. MBSFN-AreaInfoList-r16 configuration <NUM> shown in <FIG> to set-up the MBMS. One example non-optional field that may store an out-of-range value may be mcch-Offset-r9 field <NUM> shown in <FIG>. The BS <NUM> may indicate that mcch-Offset-r9 field <NUM> may have values between zero and ten. However, when BS <NUM> encodes the new configuration for the new UE <NUM> that includes the MBSFN-AreaInfoList-r9 configuration <NUM> and MBSFN-AreaInfoList-r16 configuration <NUM>, BS <NUM> may set the value of mcch-Offset-r9 field <NUM> to eleven or another value that is outside of the specified range of values between zero and ten. When the new UE 115n receives a new configuration signaling that includes the legacy MBSFN-AreaInfoList-r9 configuration <NUM> with the mcch-Offset-r9 field <NUM> set to eleven or another value outside of the range of valid values and the new MBSFN-AreaInfoList-r16 configuration <NUM>, the new UE 115n may ignore the legacy MBSFN-AreaInfoList-r9 configuration <NUM> which includes mcch-Offset-r9 field <NUM> with a value eleven and use the MBSFN-AreaInfoList-r16 configuration <NUM> to set up the MBMS.

When the legacy UE <NUM> receives the new signaling configuration that includes MBSFN-AreaInfoList-r9 configuration <NUM> with mcch-Offset-r9 set to eleven or another value outside of the range of valid values and the MBSFN-AreaInfoList-r16 configuration <NUM>, the legacy UE <NUM> may decode the mcch-Offset-r9 with a value set to eleven which indicates to the legacy UE <NUM> to ignore the MBMS signaling configuration. Thus, the legacy UE <NUM> may ignore the rest of the MBSFN-AreaInfoList-r9 configuration <NUM> and MBSFN-AreaInfoList-r16 configuration <NUM>. When the legacy UE <NUM> receives the MBSFN-AreaInfoList-r9 configuration <NUM> with the mcch-Offset-r9 field <NUM> set to a value between zero and <NUM>, the legacy UE <NUM> may establish the legacy MBMS using the MBSFN-AreaInfoList-r9 configuration <NUM>. When the new UE 115n receives the MBSFN-AreaInfoList-r9 configuration <NUM> with the mcch-Offset-r9 field <NUM> set to a value between zero and <NUM> and the MBSFN-AreaInfoList-r16 configuration <NUM>, the new UE 115n apply both the legacy and new signaling configurations within the respective MBSFN areas, provided the legacy and new configurations are valid otherwise.

In some aspects, the legacy UE <NUM> or the new UE 115n may transmit capability information of the respective UE <NUM> to BS <NUM>. The UE <NUM> may transmit the capability information in the unicast or directed groupcast transmissions. Based on the capability of the UE <NUM>, BS <NUM> may determine the legacy or new signaling configuration and transmit the RRC signaling that includes the legacy or the new signaling configuration to UE <NUM>. Accordingly, if BS <NUM> receives the capability information of the legacy UE <NUM>, the BS <NUM> may configure the legacy configuration signaling and transmit the legacy configuration signaling to the legacy UE <NUM>. The legacy signaling may have the legacy subcarrier spacing. On the other hand, if the BS <NUM> receives the capability information from the new UE <NUM>, the BS <NUM> may configure a new signaling configuration that includes the non-optional field in the legacy configuration with e.g. all bits set to zero or an out of range value, and a new configuration. The BS <NUM> may then transmit the new signaling configuration to the new UE 115n.

<FIG> is a diagram 300C that indicates a capability information message, according to aspects of the disclosure. The capabilities information message may include an mbms-ScalingFactor0dot37 field <NUM>, an mbms-ScalingFactor2dot5 field <NUM>, a timeSeparation-Slot2 field <NUM> and a timeSeparation-Slot4 field <NUM>. The mbms-ScalingFactor0dot37 field <NUM> and mbms-ScalingFactor2dot5 field <NUM> indicate that the UE <NUM> supports the subcarrier spacing of <NUM> /<NUM> for MBSFN subframes. Further the values of the mbms-ScalingFactor0dot37 field <NUM> and mbms-ScalingFactor2dot5 field <NUM> may indicate a scaling factor for processing one unit of bandwidth corresponding to the subcarrier spacing of <NUM> /<NUM> with respect to one unit of bandwidth corresponding to subcarrier spacing of <NUM>.

The timeSeparation-Slot2 field <NUM> and timeSeparation-Slot4 field <NUM> may indicate whether the UE <NUM> supports time staggering lengths of <NUM> or <NUM> slots for PMCH with the subcarrier spacing of <NUM> for MBSFN subframes.

In some aspects, the UE <NUM> may transmit its capability information prior to BS <NUM> generating the legacy configuration signaling or the new configuration signaling for, e.g. setting up the MBMS. In response, BS <NUM> may generate transmit the legacy configuration signaling or the new configuration signaling for the MBMS based on the capability information.

Notably, while the aspects above are described with respect to the signaling that establishes backward compatibility for the MBMS, the embodiments are also applicable to establishing backward compatibility for other types of signaling.

<FIG> is a block diagram of an exemplary UE <NUM> according to embodiments of the present disclosure. As shown, the UE <NUM> may include a processor <NUM>, a memory <NUM>, signal decoder <NUM>, a transceiver <NUM> including a modem subsystem <NUM> and a radio frequency (RF) unit <NUM>, and one or more antennas <NUM>. These elements may be in direct or indirect communication with each other, for example via one or more buses.

The processor <NUM> may include a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a controller, a field programmable gate array (FPGA) device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein.

The memory <NUM> may include a cache memory (e.g., a cache memory of the processor <NUM>), random access memory (RAM), magnetoresistive RAM (MRAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), flash memory, solid state memory device, hard disk drives, other forms of volatile and non-volatile memory, or a combination of different types of memory. In some aspects, the memory <NUM> includes a non-transitory computer-readable medium. The instructions <NUM> may include instructions that, when executed by the processor <NUM>, cause the processor <NUM> to perform the operations described herein with reference to the UEs <NUM> in connection with embodiments of the present disclosure. Instructions <NUM> may also be referred to as code. The terms "instructions" and "code" should be interpreted broadly to include any type of computer-readable statement(s). For example, the terms "instructions" and "code" may refer to one or more programs, routines, sub-routines, functions, procedures, etc. "Instructions" and "code" may include a single computer-readable statement or many computer-readable statements.

The signal decoder <NUM> may be used for various aspects of the disclosure. Signal decoder <NUM> may decode signaling configurations, including signaling configurations included in the RRC signaling and associated with the MBMS service. In particular, signal decoder <NUM> may decode signaling configuration, such as MBMS legacy and MBMS new configurations for both legacy and new UEs <NUM>, 115n.

As shown, the transceiver <NUM> may include the modem subsystem <NUM> and the RF unit <NUM>. The transceiver <NUM> can be configured to communicate bi-directionally with other devices, such as the BSs <NUM>. The modem subsystem <NUM> may be configured to modulate and/or encode the data from the memory <NUM> according to a modulation and coding scheme (MCS), e.g., a low-density parity check (LDPC) coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc. The RF unit <NUM> may be configured to process (e.g., perform analog to digital conversion or digital to analog conversion, etc.) modulated/encoded data from the modem subsystem <NUM> (on outbound transmissions) or of transmissions originating from another source such as a UE <NUM> or a BS <NUM>. The RF unit <NUM> may be further configured to perform analog beamforming in conjunction with the digital beamforming. Although shown as integrated together in transceiver <NUM>, the modem subsystem <NUM> and the RF unit <NUM> may be separate devices that are coupled together at the UE <NUM>, including UE <NUM>, 115n to enable the UE <NUM> to communicate with other devices.

The RF unit <NUM> may provide the modulated and/or processed data, e.g. data packets (or, more generally, data messages that may contain one or more data packets and other information), to the antennas <NUM> for transmission to one or more other devices. This may include, for example, transmission of the capability information and MBMS data according to embodiments of the present disclosure. The antennas <NUM> may further receive data messages transmitted from other devices. This may include, for example, reception of the legacy and new signaling configuration for the MBMS that is included in the RRC signaling. The antennas <NUM> may provide the received data messages for processing and/or demodulation at the transceiver <NUM>. The antennas <NUM> may include multiple antennas of similar or different designs in order to sustain multiple transmission links. The RF unit <NUM> may configure the antennas <NUM>.

<FIG> is a block diagram of an exemplary BS <NUM> according to embodiments of the present disclosure. The BS <NUM> may be a BS <NUM> as discussed above. A shown, the BS <NUM> may include a processor <NUM>, a memory <NUM>, signal encoder <NUM>, a transceiver <NUM> including a modem subsystem <NUM> and a RF unit <NUM>, and one or more antennas <NUM>. These elements may be in direct or indirect communication with each other, for example via one or more buses.

The signal encoder <NUM> may be used for various aspects of the disclosure. Signal decoder <NUM> may encode signaling configurations to be included in the RRC signaling, including signaling configurations for the MBMS that are transmitted using uncast transmission, broadcast transmission, or groupcast transmission to UEs <NUM>, <NUM>. In particular, signal decoder <NUM> may encode signaling configurations, e.g. MBMS legacy and MBMS new configurations for both legacy and new UEs 115n, <NUM> and may include backward capability for signaling configurations.

As shown, the transceiver <NUM> may include the modem subsystem <NUM> and the RF unit <NUM>. The transceiver <NUM> can be configured to communicate bi-directionally with other devices, such as the UEs <NUM> and/or another core network element. The modem subsystem <NUM> may be configured to modulate and/or encode data according to a MCS, e.g., a LDPC coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc. The RF unit <NUM> may be configured to process (e.g., perform analog to digital conversion or digital to analog conversion, etc.) modulated/encoded data from the modem subsystem <NUM> (on outbound transmissions) or of transmissions originating from another source such as a UE <NUM>. The RF unit <NUM> may be further configured to perform analog beamforming in conjunction with the digital beamforming. Although shown as integrated together in transceiver <NUM>, the modem subsystem <NUM> and the RF unit <NUM> may be separate devices that are coupled together at the BS <NUM> to enable the BS <NUM> to communicate with other devices.

The RF unit <NUM> may provide the modulated and/or processed data, e.g. data packets (or, more generally, data messages that may contain one or more data packets and other information), to the antennas <NUM> for transmission to one or more other devices. This may include, for example, transmission of information to complete attachment to a network and communication with a camped UE <NUM> and also transmission of the legacy and/or new signaling configuration for the MBMS service, according to embodiments of the present disclosure. The antennas <NUM> may further receive data messages transmitted from other devices, including capability information from the UE <NUM> and provide the received data messages for processing and/or demodulation at the transceiver <NUM>. The antennas <NUM> may include multiple antennas of similar or different designs in order to sustain multiple transmission links.

<FIG> is a flow diagram of a method <NUM> according to some aspects of the disclosure. Steps of the method <NUM> can be executed by a computing device (e.g., a processor, processing circuit, and/or other suitable component) of a wireless communication device or other suitable means for performing the steps. For example, a wireless communication device, such as the BS <NUM> may utilize one or more components, such as the processor <NUM>, the signal encoder <NUM>, the transceiver <NUM>, the modem <NUM>, and the one or more antennas <NUM>, to execute the steps of method <NUM>. As illustrated, the method <NUM> includes a number of enumerated steps, but aspects of the method <NUM> may include additional steps before, after, and in between the enumerated steps. In some aspects, one or more of the enumerated steps may be omitted or performed in a different order.

At step <NUM>, a new signaling configuration with backward compatibility is determined. The new signaling configuration is included in the RRC signaling to set up the MBMS. The new signaling configuration may be the new MBMS configuration that sets up the MBMS. BS <NUM> determines a new signaling configuration for the new UE 115n that is backward compatible with the legacy configuration for the legacy UE <NUM>. The new signaling configuration includes the legacy configuration (legacy MBMS configuration) with information in a mandatory or non-optional field and a new configuration. BS <NUM> identifies the mandatory or non-optional field in the legacy configuration and includes a value in the mandatory or non-optional field that causes the legacy UE <NUM> to decode the legacy configuration correctly but to ignore the configuration. An example non-optional field may have a value with all bits set to zero, value that is out of range from available values, or another value that may be decoded correctly but indicates to the legacy UE <NUM> to ignore the configuration and, for example, to ignore setting up the new MBMS that has new sub-carrier spacing on the legacy UE <NUM>. BS <NUM> also includes a new configuration in the new signaling configuration. The new configuration may be decoded by the new UE 115n to, for example, establish an MBMS. An example new signaling configuration may indicate new sub-carrier spacing used in the MBMS by the new UE 115n.

At step <NUM>, the new signaling configuration is transmitted. For example, BS <NUM> may transmit the new signaling configuration, including the legacy configuration with a set mandatory or non-optional field and the new configuration. The signaling configuration may be included as part of the RRC signaling to the new and legacy UEs 115n, <NUM> in the network <NUM>. The transmission may be a broadcast transmission, groupcast transmission or unicast transmission.

<FIG> is a flow diagram of a method <NUM> according to some aspects of the disclosure. Steps of the method <NUM> can be executed by a computing device (e.g., a processor, processing circuit, and/or other suitable component) of a wireless communication device or other suitable means for performing the steps. For example, a wireless communication device, such as the UE <NUM>, <NUM> may utilize one or more components, such as the processor <NUM>, the memory <NUM>, signal decoder <NUM>, the transceiver <NUM>, the modem <NUM>, and the one or more antennas <NUM>, to execute the steps of method <NUM>. As illustrated, the method <NUM> includes a number of enumerated steps, but aspects of the method <NUM> may include additional steps before, after, and in between the enumerated steps. In some aspects, one or more of the enumerated steps may be omitted or performed in a different order.

At step <NUM>, the new signaling configuration is decoded at an old or legacy UE. For example, the legacy UE <NUM> may receive the new signaling configuration (e.g. new MBMS signaling configuration) a part of the RRC signaling that sets up an MBMS. The new signaling configuration may be configured in step <NUM> and includes a mandatory or non-optional field in the legacy configuration and the new configuration. As discussed above, the new signaling configuration may be included in the RRC signaling for setting up the MBMS that includes sub-carrier spacing in a sub frame that is different from the sub-carrier spacing used by the legacy MBMS.

At step <NUM>, the mandatory or non-optional field in the legacy configuration portion of the new signaling configuration is decoded at the legacy UE. For example, the legacy UE <NUM> decodes the mandatory or non-optional field in the legacy configuration (e.g. legacy MBMS configuration) portion of the new signaling configuration. The legacy UE <NUM> determines that the non-optional field includes a value that indicates an error, e.g. all bits are set to zero, the value is out of range of expected values, etc. When the value indicates an error, the legacy UE <NUM> determines that the new signaling configuration is to be ignored.

At step <NUM>, the new signaling configuration is ignored by the legacy UE. For example, the legacy UE <NUM> ignores the new signaling configuration because of an unexpected or error value in the non-optional field. Thus, the legacy UE <NUM> does not set up the new MBMS.

<FIG> is a flow diagram of a method <NUM> according to some aspects of the disclosure. Steps of the method <NUM> can be executed by a computing device (e.g., a processor, processing circuit, and/or other suitable component) of a wireless communication device or other suitable means for performing the steps. For example, a wireless communication device, such as the UE <NUM>, <NUM>, may utilize one or more components, such as the processor <NUM>, the memory <NUM>, signal decoder <NUM>, the transceiver <NUM>, the modem <NUM>, and the one or more antennas <NUM>, to execute the steps of method <NUM>. As illustrated, the method <NUM> includes a number of enumerated steps, but aspects of the method <NUM> may include additional steps before, after, and in between the enumerated steps. In some aspects, one or more of the enumerated steps may be omitted or performed in a different order.

At step <NUM>, the new signaling configuration is decoded at a new UE. For example, the new UE 115n may receive a new signaling configuration in the new RRC signaling that sets up an MBMS at the new UE 115n. The new signaling configuration may be configured in step <NUM> and includes a mandatory or non-optional field in the legacy configuration and a new configuration. As discussed above, the new signaling configuration may set up a new MBMS that includes sub-carrier spacing in a sub frame that is different from the sub-carrier spacing in the legacy MBMS.

At step <NUM>, the mandatory or non-optional field in the legacy configuration portion of the new signaling configuration is decoded at the new UE. For example, the new UE 115n decodes the mandatory or non-optional field in the legacy configuration portion of the new signaling configuration and determines that the field includes a value that indicates that the new configuration should be decoded, at which point the method proceeds to step <NUM>. Step <NUM> may be optional in some instances, and the new UE 115n may proceed from step <NUM> to step <NUM>.

At step <NUM>, the new signaling is decoded. For example, the new UE 115n decodes the new configuration in the new signaling configuration. As discussed above, the new configuration may indicate sub-carrier spacing for the MBMS that may be used by the new UE 115n. The new UE 115n decodes the new configuration to determine the sub-carrier spacing.

At step <NUM>, the control information is received using the new configuration. For example, the UE 115n may receive control information associated with the MBMS. The control information may be carried by a sub-frame in a radio frame on a sub-carrier indicated by the new signaling configuration.

Claim 1:
A method of wireless communication by a base station (<NUM>), comprising:
determining (<NUM>), at the base station (<NUM>), a multimedia broadcast multicast service, MBMS, configuration, wherein the MBMS configuration includes at least one non-optional field with all bits of the non-optional field set to zero wherein all the bits set to zero is an indication that the MBMS configuration is associated with a second UE (<NUM>-n) having a second MBMS capability; wherein the second MBMS capability is different from a first MBMS capability of a first UE; and
broadcasting (<NUM>) the MBMS configuration to a first UE (<NUM>) and the second UE(115n).