WO2021190596A1

WO2021190596A1 - Control information scheduling and modification notification for multicast and broadcast

Info

Publication number: WO2021190596A1
Application number: PCT/CN2021/082965
Authority: WO
Inventors: Xuelong Wang
Original assignee: Mediatek Singapore Pte. Ltd.
Priority date: 2020-03-25
Filing date: 2021-03-25
Publication date: 2021-09-30
Also published as: WO2021189307A1

Abstract

Apparatus and methods are provided for control information scheduling and modification notification for multicast and broadcast. In one novel aspect, the control information for MBS is transmitted by multiple MCCHs each with independent MCCH notification cycle. The MCCH notification cycle is calculated based on scaling of cell specific MBS DRX cycle via a scaling factor. In one embodiment, the MCCH is scheduled by an MCCH DCI with CRC scrambled by MBMS RNTI (M-RNTI). In another embodiment, MCCH control information is scheduled with a repetition cycle and repetition factor within MCCH notification cycle. In one embodiment, a resource pool is allocated with a number of MBS notification frames (NFs) for MBS control information transmission and modification notification. In one embodiment, the NF has a number of notification occasions. In one embodiment, the configuration of the MBS parameters for MCCH reception for MBS services are transmitted by an MBS specific SIB.

Description

CONTROL INFORMATION SCHEDULING AND MODIFICATION NOTIFICATION FOR MULTICAST AND BROADCAST

CROSS REFERENCE TO RELATED APPLICATIONS

This application is filed under 35 U.S.C. §111 (a) and is based on and hereby claims priority under 35 U.S.C. §120 and §365 (c) from International Application No. PCT/CN2020/081157, titled “Methods and Apparatus of Control Information Scheduling and Modification Notification for Multicast and Broadcast Service, ” with an international filing date of March 25, 2020. The disclosure of each of the foregoing documents is incorporated herein by reference.

TECHNICAL FIELD

The disclosed embodiments relate generally to wireless communication, and, more particularly, to control information scheduling and modification notification for multicast and broadcast.

BACKGROUND

With the exponential growth of wireless data services, content delivery to large mobile user groups has grown rapidly. Initial wireless multicast/broadcast services, the multicast and include streaming services such as mobile TV and IPTV. With the growing demand for large group content delivery, recent application development for mobile multicast services requires highly robust and critical communication services such as group communication in disaster situations and the necessity of public safety network-related multicast services. The early 3GPP LTE standard defines enhanced multimedia broadcast multicast services eMBMS. The single-cell point to multipoint (SC-PTM) services and multicast-broadcast single-frequency network (MBSFN) are defined. The traditional MBMS control information is carried by multicast control channel (MCCH) logical channel. The MCCH is transmitted with a fixed repetition period within a modification period. The MCCH is repeated at each repetition period within a modification period. The modification period is a multiple of the repetition period. Changes in MCCH information is only performed at the boundary of modification period and is not performed in the middle of a modification period. The fixed timing for transmission of the MCCH is not flexible since all multicast traffic channels (MTCHs) and all UEs share one mCCH repetition period and modification period. In general, different MBS application and its services require different cycle for transmission and control information. The applications of new radio (NR) broadcast and multicast technology includes V2X use cases, public safety usage, video streaming transmission, software upgrade, etc. The traditional fixed timing transmission of MCCH does not provide a way to serve the rapid growing multicast and broadcast services.

Improvements and enhancements are required to support flexible MCCH notification and modification for multicast and broadcast services.

SUMMARY

Apparatus and methods are provided for control information scheduling and modification notification for multicast and broadcast. In one novel aspect, the control information for MBS is transmitted by multiple MCCHs each with independent MCCH notification cycle. The MCCH notification cycle is calculated based on scaling of cell specific MBS DRX cycle via a scaling factor. In one embodiment, the MCCH is scheduled by an MCCH DCI with CRC scrambled by MBMS RNTI (M-RNTI) . The MCCH DCI includes one or more MCCH elements comprising an indicator of an existence of scheduling information for MCCH transmission, an indicator of an existence of scheduling information for MCCH notification, a one-bit indicator of modification of MCCH information, and an indicator to indicate the start of a new service and a change of an ongoing service with a different MCCH notification cycle. In another embodiment, MCCH control information is scheduled with a repetition cycle and repetition factor within MCCH notification cycle. The modification notification is only indicated at the boundary of MCCH notification cycle. In one embodiment, a resource pool is allocated with a number of MBS notification frames (NFs) for MBS control information transmission and modification notification. In one embodiment, the NF has a number of notification occasions for MBS control information transmission and modification notification. The UEs that are interested in a particular MBS service or MBS service group only monitors the NFs according to the MCCH notification cycle configured for the MBS service or MBS service group. In one embodiment, the configuration of the MBS parameters for MCCH reception for MBS services are transmitted by an MBS specific SIB. The MBS specific SIB is defined to carry MCCH information, which contains the MBS DRX configuration of the cell and one or more MBS services or MBS service groups. The MBS DRX configuration of the cell includes one or more the information elements, including the MBS DRX cycle, the number of NFs within the MBS DRX cycle, the frame offset, the number of notification occasions within each NF, and the first PDCCH monitoring occasion for each notification occasion of the NF. The MBS service group includes one or more of the information elements, including the MBS service group identity, the MBS scaling factor (or MCCH notification cycle) , and corresponding MCCH LCID. Optionally, the MBS service group further includes the MCCH repetition cycle and repetition factor for each MBS service group.

This summary does not purport to define the invention. The invention is defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, where like numerals indicate like components, illustrate embodiments of the invention.

Figure 1 is a schematic system diagram illustrating an exemplary NR wireless network that supports control information scheduling and modification notification for multicast and broadcast in accordance with embodiments of the current invention.

Figure 2A illustrates an exemplary NR wireless system with centralized higher layers of the NR radio interface stacks and UE stack with multicast protocol and unicast protocol in accordance with embodiments of the current invention.

Figure 2B illustrates exemplary diagrams for group-based MCCH information provision and updates in the NR network in accordance with embodiments of the current invention.

Figure 3 illustrates an exemplary NR MBS DRX cycle with notification frame configuration in accordance with embodiments of the current invention.

Figure 4 illustrates an exemplary diagram for the MCCH notification allocation within one NR MBS DRX cycle with different scaling factors in accordance with embodiments of the current invention.

Figure 5 illustrates an exemplary diagram for the NF allocation of different MCCH notification cycles within one NR MBS DRX cycle in accordance with embodiments of the current invention.

Figure 6 illustrates exemplary diagrams of MCCH notification allocation for repeated MCCH transmission and/or modification notification within one NR MBS DRX cycle in accordance with embodiments of the current invention.

Figure 7A illustrates exemplary diagrams of MCCH notification information and MBS configuration MCCH transmission and/or modification notification in accordance with embodiments of the current invention.

Figure 7B illustrates exemplary diagrams for MBS specific SIB carrying MCCH information in accordance with embodiments of the current invention.

Figure 8 illustrates an exemplary procedure for MCCH control information transmission in accordance with embodiments of the current invention.

Figure 9 illustrates an exemplary flow chart for the control information scheduling and modification notification for multicast and broadcast in accordance with embodiments of the current invention.

DETAILED DESCRIPTION

Reference will now be made in detail to some embodiments of the invention, examples of which are illustrated in the accompanying drawings.

Aspects of the present disclosure provide methods, apparatus, processing systems, and computer readable mediums for NR (new radio access technology, or 5G technology) or other radio access technology. NR may support various wireless communication services, such as enhanced mobile broadband targeting wide bandwidth, millimeter wave targeting high carrier frequency, massive machine type communications targeting non -backward compatible machine type communication (MTC) techniques, and/or mission critical targeting ultra-reliable low-latency (URLLC) communications. These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTI) to meet respective quality of service (QoS) requirements. In addition, these services may co-exist in the same subframe.

Figure 1 is a schematic system diagram illustrating an exemplary NR wireless network that supports control information scheduling and modification notification for multicast and broadcast in accordance with embodiments of the current invention. NR wireless system 100 includes one or more fixed base infrastructure units forming a network distributed over a geographical region. The base unit may also be referred to as an access point, an access terminal, a base station, a Node-B, an eNode-B (eNB) , a gNB, or by other terminology used in the art. The network can be a homogeneous network or heterogeneous network, which can be deployed with the same frequency or different frequency. gNB 101 and gNB 102are base stations in the NR network, the serving area of which may or may not overlap with each other. The backhaul connection, such as 136, connects the non-co-located receiving base units, such as gNB 101 and gNB 102. These backhaul connections can be either ideal or non-ideal. gNB 101 connects with gNB 102 via Xnr interface.

NR wireless network 100 also includes multiple communication devices or mobile stations, such user equipments (UEs) such as

UEs

111, 112, 113, 114, 116, 117, 121, and 122. The exemplary mobile devices in wireless network 100 have sidelink capabilities. The mobile devices can establish one or more unicast connections with one or more base stations. For example, UE 111 has unicast connection 131 with gNB 101.

UEs

114 and 115 connect with gNB 101 with

unicast connections

133 and 134, respectively. Similarly, UE 121 connects with gNB 102 with unicast connection 132.

In one novel aspect, enhanced control information scheduling and modification notification for multicast and broadcast are supported. A multicast service-1 is provided by gNB 101 and gNB 102.

UEs

111, 112 and 113 receive multicast services from gNB 101. UEs 121 and 122 receive multicast services from gNB 102. Multicast service-2 is provided by gNB 101 to the UE group of UEs 116, 117, and 118. Multicast service-1 and multicast service-2 are delivered in multicast mode with a multicast radio bearer (MRB) configured by the NR wireless network. Multicast service-1 and multicast service-2 provides MCCH notification to UEs with independent notification cycle. The receiving UEs receive MCCH notification information from DCI and monitors MCCH notifications based on MBS configurations.

In one novel aspect, NR multicast is transmitted in the coverage of a cell. From logical channel perspective, the MCCH and MTCH are mapped on DL-SCH. The scheduling for NR multicast is done by the gNB. MCCH provides the information of a list of NR multicast services with ongoing sessions transmitted on MTCH (s) . At physical layer, MTCH is scheduled by gNB in the common search space of PDCCH with G-RNTI scrambled. UE decodes the MTCH data for a multicast session in the multicast PDSCH according to the resource indicated by DCI.

Figure 1 further illustrates simplified block diagrams of a base station and a mobile device/UE for control information scheduling and modification notification for multicast and broadcast. gNB 102 has an antenna 156, which transmits and receives radio signals. An RF transceiver circuit 153, coupled with the antenna, receives RF signals from antenna156, converts them to baseband signals, and sends them to processor 152. RF transceiver 153 also converts received baseband signals from processor152, converts them to RF signals, and sends out to antenna 156. Processor 152 processes the received baseband signals and invokes different functional modules to perform features in gNB 102. Memory 151 stores program instructions and data 154 to control the operations of gNB 102. gNB 102also includes a set of control modules 155 that carry out functional tasks to communicate with mobile stations.

Figure 1 also includes simplified block diagrams of a UE, such as UE 111. The UE has an antenna 165, which transmits and receives radio signals. An RF transceiver circuit 163, coupled with the antenna, receives RF signals from antenna165, converts them to baseband signals, and sends them to processor 162. In one embodiment, the RF transceiver may comprise two RF modules (not shown) . A first RF module is used for HF transmitting and receiving, and the other RF module is used for different frequency bands transmitting and receiving which is different from the HF transceiver. RF transceiver 163 also converts received baseband signals from processor162, converts them to RF signals, and sends out to antenna 165. Processor 162 processes the received baseband signals and invokes different functional modules to perform features in the UE 111. Memory 161 stores program instructions and data 164 to control the operations of the UE 111. Antenna 165 sends uplink transmission and receives downlink transmissions to/from antenna 156 of gNB 102.

The UE also includes a set of control modules that carry out functional tasks. These control modules can be implemented by circuits, software, firmware, or a combination of them. A configuration module 191 configures a plurality of multicast broadcast services (MBSs) , wherein control information for the plurality of MBSs are received on multiple multicast control channels (MCCHs) each with an independent MCCH notification cycle. An MBS notification module 192 receives an MBS configuration of MCCH notification for the configured MBSs. A monitor module 193 monitors MCCH notifications for each corresponding configured MCCH notification based on the MBS configuration, wherein each MCCH notification cycle is based on a scaling of cell-specific MBS DRX cycle associated with a scaling factor S. An MBS receiver 194 receives the plurality of MBSs based on detected plurality of MCCH notifications for corresponding MBSs.

Figure 2A illustrates an exemplary NR wireless system with centralized higher layers of the NR radio interface stacks and UE stack with multicast protocol and unicast protocol in accordance with embodiments of the current invention. Different protocol split options between central unit (CU) and distributed unit (DU) of gNB nodes may be possible. The functional split between the CU and DU of gNB nodes may depend on the transport layer. Low performance transport between the CU and DU of gNB nodes can enable the higher protocol layers of the NR radio stacks to be supported in the CU, since the higher protocol layers have lower performance requirements on the transport layer in terms of bandwidth, delay, synchronization and jitter. In one embodiment, SDAP and PDCP layer are located in the CU, while RLC, MAC and PHY layers are located in the DU. A core unit 201 is connected with one central unit 211 with gNB higher layer 252. In one embodiment 250, gNB higher layer 252 includes the PDCP layer and optionally the SDAP layer. Central unit 211 connects with distributed

units

221, 222, and 221. Distributed

units

221, 222, and 223 each corresponds to a cell 231, 232, and 233, respectively. The DUs, such as 221, 222 and 223 includes gNB lower layers 251. In one embodiment, gNB lower layers 251 include the PHY, MAC and the RLC layers. In another embodiment 260, each gNB has the protocol stacks 261 including SDAP, PDCP, RLC, MAC and PHY layers.

Figure 2B illustrates exemplary diagrams for group-based MCCH information provision and updates in the NR network in accordance with embodiments of the current invention. The NR multicast is transmitted in the coverage of a cell. From logical channel perspective, the MCCH and MTCH are mapped on DL-SCH. The scheduling for NR multicast is done by the gNB. MCCH provides the information of a list of NR multicast services with ongoing sessions transmitted on MTCH (s) . At physical layer, MTCH is scheduled by gNB in the common search space (CSS) of PDCCH with G-RNTI scrambled. The UE decodes the MTCH data for a multicast session in the multicast PDSCH according to the resource indicated by DCI. Different MBS applications and their services require different cycle for transmitting the control information. In a cell, a number of MBS 290 are supported, with each, MBS 291, 292, 293, and 294, carried by an independent MTCH. UE 202 is configured with MBS 292 and MBS 293. A single MCCH or multiple MCCHs are supported to transmit the control information of all or a group of the MTCHs. MCCH-1270 are configured to transmit control information for the MTCH supporting MBS 292. MCCH-2280 are configured to support MTCHs that carry MBS 291, MBS 293, and MBS 294. The configuration of only a single MCCH repetition period and modification period for these MBS services is not power consumption friendly and not flexible enough. On one hand, some of UEs may experience delay when attempting to read the update of MCCH control information, on the other hand, some of UEs may read the MCCH control information too often to save the UE power. Both cases are not desirable to the UE and the network for NR multicast and broadcast services.

MCCH mainly carries the identities of MBS services and their scheduling information (e.g. G-RNTI) . The change of MCCH information include two cases. One case is to start one or a plural of new MBS service. The other case is to modify or stop one or a plural of ongoing MBS service. A specific modification notification is sent together with MCCH control information carried by a MCCH when there is modification on the MCCH control information. Both modification notification and MCCH control information are addressed by a common RNTI in order to reduce UE’s complexity for the search at PDCCH search space. The modification notification is piggybacked by the DCI scheduling the transmission of MCCH control information in the current MCCH notification cycle. When the transmission of MCCH information is repeated, the modification notification is piggybacked by the first DCI scheduling the transmission of MCCH information within the MCCH notification cycle or by all of the DCIs that schedules the transmission of MCCH information within the MCCH notification cycle. MCCH-1270 is configured with MCCH-1 repetition period 272. MCCH is configured with four repetitions within one MCCH-1 notification period N 272. A MCCH-1 also carries modification information. At period 273 the MCCH-1 modification period (N+1) including four MCCH-1 repetition for notifications are configured. For MCCH-2280, one notification frame is configured with one MCCH-2 repetition period 281. The MCCH-2 modification period 282 includes four notification frames.

The MCCH control information transmission and modification notification can be subject to discontinuous reception (DRX) like operation, in order to reduce UE power saving. This means the UEs can only monitor the PDCCH at the occasions as defined by the given MCCH notification cycle to check if there is any transmitted MCCH control information and/or modification notification. The delivery of the MCCH control information by the network can be subject to discontinuous transmission (i.e. DTX) . In one novel aspect, the MCCH control information transmission by network is stopped at some MCCH notification cycles, which is indicated by the DCI. When there is no MCCH control information transmission by the DCI, the UE will skip the decoding/receiving of the PDSCH. A specific MBS DRX cycle is defined for NR MBS control information transmission and modification notification within a particular cell. Within the MBS DRX cycle, a pool of transmission resources are allocated for NR MBS control information transmission and modification notification. The number of radio frames is defined within the resource pool. The radio frame for MBS control information transmission and modification notification is called the notification frame (NF) . The NF may only carry MBS control information transmission and there is no modification notification. The NF may carry both MBS control information transmission and modification notification indicator. In one embodiment, one radio frame in the pool may include one, two or four MBS notification occasions. The network selects one notification occasion within a particular NF to transmit the MBS control information transmission and/or modification notification. Accordingly, the UE selects the same notification occasion to perform reception. The UEs that are interested in a particular MBS service or MBS service group only monitors the notification frames according to the MCCH notification cycle configured for the MBS service or MBS service group. Different UEs that are interested in different MBS service (s) or MBS service group (s) may monitor different notification frames with diverse time interval. This principle applies to the PDCCH monitoring for both MCCH control information reception and MCCH modification notification. The unit of MBS DRX cycle and MCCH notification cycle can be one radio frame (i.e. 10ms) and the value of MBS DRX cycle and MCCH notification cycle are integer multiples of radio system frames.

Figure 3 illustrates an exemplary NR MBS DRX cycle with notification frame configuration in accordance with embodiments of the current invention. The MBS DRX cycle 380 is defined as 1280ms (i.e. one hundred and twenty-eight radio frames) . For simplicity, in the example, the MBS DRX cycle starts from system frame number (SFN) one. As an example, sixteen MBS notification frames, such as

NF

310, 320, and 370, are included in the MBS DRX cycle 380, each with two independent MBS notification occasions configured. Then in total, there are thirty-two MBS notification occasions, such as 311, 312, 321, 322, 371, and 372, within one MBS DRX cycle 380. Different MBS notification occasions within an MBS notification frame (NF) may be located at different subframes or slots within the same radio frame. For example, the first NF 310 starts from the first radio frame (SFN=1) . The frame offset for NF 310 is zero. The second NF 320, with NF=2, starts with SFN=9, while the last NF 370, with NF=16, starts with SFN=129. Within a cell, the control information and modification notification of different MBS services are scheduled with variable length of MCCH notification cycle. The MCCH notification cycle is also known as MCCH modification cycle or MCCH modification period. The length of a MCCH notification cycle is the shortest cycle when the MCCH modification notification can be transmitted to the UE. The length of a MCCH notification cycle indicates how often the UE needs to monitor PDCCH occasions to check if there is updated MCCH information.

For the NR MBS service that changes slowly (e.g. for delay tolerant MBS service) , a long MCCH notification cycle can be configured. The longest MCCH notification cycle within a cell is the configured MBS DRX cycle. For the NR MBS service that is subject to dynamic change, a short MCCH notification cycle is configured. A scaling factor is an integer defined to calculate the exact length of MCCH notification cycle. The configured MBS DRX cycle (e.g. expressed by MBS-DRX-cycle) for a cell is scaled by a configured scaling factor S (e.g. expressed by Scaling-Factor) to derive the MCCH notification cycle (e.g. expressed by MCCH-Notification -cycle) . In one embodiment, MCCH-Notification-cycle=MBS-DRX-cycle div Scaling-Factor. For example, the scaling factor S is configured to be {1, 2, 4, 8 or 16} . The shortest MCCH notification cycle is one-sixteenth of the MBS DRX cycle for cell when the scaling factor S=16. In other embodiments, the MCCH notification cycle and the occupied notification frames of an MBS service is determined by both scaling factor S and the system frame offset for MCCH.

Figure 4 illustrates an exemplary diagram for the MCCH notification allocation within one NR MBS DRX cycle with different scaling factors in accordance with embodiments of the current invention. The MBS DRX cycle is defined as 1280ms (i.e. 128 radio frames) . Sixteen MBS notification frames are included in the MBS DRX cycle. The shortest MCCH notification cycle 401 is one-sixteenth of MBS DRX cycle. There are sixteen MCCH notification cycles within one configured MBS DRX cycle for the cell. In one example, the shortest MCCH notification cycle 401 is configured based on zero system frame offset. The longest MCCH notification cycle 403 is the full MBS DRX cycle. There is only one MCCH notification cycle within one configured MBS DRX cycle within the cell. In another example, MCCH notification cycle 402 is one-fourth of MBS DRX cycle. There are two MCCH notification cycles within one configured MBS DRX cycle. MCCH notification cycle 402, as shown has the system frame offset configured to be five radio frames. When the control information of a MBS service is transmitted from the cell to the UEs with a shorter MCCH notification cycle within the configured MBS DRX cycle, the UEs are expected to read the MCCH more frequently. Otherwise, the UEs reads the MCCH less frequently. The UEs interested in receiving different services may read different MCCHs at different time and/or with different frequency. The same principle applies to the UEs receiving ongoing MBS services.

Figure 5 illustrates an exemplary diagram for the NF allocation of different MCCH notification cycles within one NR MBS DRX cycle in accordance with embodiments of the current invention. The MBS DRX cycle 511 is configured to be 1280ms. The first MBS service 521 is configured with a MCCH notification cycle 320ms and zero SFN offset. Then there are four NFs of this MBS service. The second MBS service 522 is configured with a MCCH notification cycle 640ms and SFN_offset=16. The sixteen SFN offset equals two NFs offset because there are eight system-frame intervals between two consecutive NFs. There are two NFs valid for the second MBS service within one MBS DRX cycle. The third MBS service 523 is configured with a MCCH notification cycle 1280ms and SFN_offset=24, which is three NFs offset. There is only one NF valid for MBS service 523 in one MBS DRX cycle.

Figure 6 illustrates exemplary diagrams of MCCH notification allocation for repeated MCCH transmission and/or modification notification within one NR MBS DRX cycle in accordance with embodiments of the current invention. An MBS MCCH notification configuration 610 has the MBS DRX cycle 611 configured to be 1280ms, an initial MCCH notification 615 with notification cycle=320ms, and a repeated MCCH notification 616 with repetition cycle=80ms. In one embodiment, the notification of an MBS service and the transmission of the actual control information of the MBS service is repeated once or more times to allow UEs to receive the missed notification in the repeated notification frames within the configured MCCH notification cycle. The MBS service is configured with a MCCH notification cycle of 320ms and zero SFN offset. There are four NFs valid for the initial transmission of the control information and/or notification of this MBS service. As an example, the MBS service is configured with a repetition cycle 612 of 80ms (i.e. eight system frames) . Then there are four repeated transmissions of the control information and/or notification for this MBS service. Each initial transmission is only repeated once for this MBS service. In different scenarios, depending on the configuration of the repetition cycle, the initial transmission can be repeated once or a plural of times within the configured MCCH notification cycle.

The repetition pattern is based on the configuration of both the repetition cycle and a repetition factor. The repetition cycle defines the time interval between the initial transmission and its repetitions. The unit of repetition cycle is one radio frame (i.e. 10ms) and the repetition cycle is an integer of multiple radio system frames. The repetition factor is an integer, which defines how many times the same MCCH control information and/or MCCH notification repeats at a given MCCH notification cycle repeats. The configuration of repetition cycle and repetition factor are correlated. A particular repetition cycle may only support a limited set of repetition factor. The repetition cycle for the MBS service is eight radio frames (i.e. 80ms) and the repetition factor is one, which defines a single repeated transmission for the MCCH control information and/or MCCH notification. The configurable repetition factors for 610 are one, two and three since there are only three unoccupied NFs within the given MCCH notification cycle. The scaling factor S for a particular MBS service restricts the configurable repetition factors since unoccupied NFs within the given MCCH notification cycle is determined by the scaling factor. Diagram 620 illustrates an MBS MCCH notification configuration with the MBS DRX cycle 621 configured to be 1280ms, an initial MCCH notification 625 with notification cycle=320ms, a repeated MCCH notification 626 with repetition cycle=80ms, and a repetition factor 623 to be two.

The repeated transmission of the initial MCCH control information and/or MCCH notification can also be configured to skip one or a plural of follow-up NFs. MBS MCCH notification configuration 630 has the MBS DRX cycle 631 configured to be 1280ms, an initial MCCH notification 635 with notification cycle=320ms, arepeated MCCH notification 636 with repetition cycle=160ms, and a repetition factor 633 to be one. The repeated transmission can occur at the third NF in 630. The repetition cycle 632 is 160ms (i.e. sixteen system frames) . There is no additional configurable repetition factor other than one. The transmission pattern of MCCH transmission and/or notification equals to the transmission pattern of the MCCH control information and/or MCCH notification with a 320ms MCCH notification cycle and zero SFN offset since 320 ms MCCH notification cycle within 1280ms configured MBS DRX cycle means eight occurrence of transmission and/or notification.

In certain systems, such as NR system, one cell typically supports the simultaneous transmission of a large number of MBS services (e.g. 1024 services) . It would be difficult to assign a unique MCCH notification cycle to each MBS service since the available NFs within an MBS DRX cycle are usually limited. In one embodiment, multiple notification occasions are configured within the NFs to host different MBS services sharing the same MCCH notification cycle. However, the available of notification occasions within a notification frame are usually also limited. For example, in the NR network, the maximum configuration of notification occasions within a notification frame is four.

In one embodiment, a plurality of MBS services are grouped together to from a MBS service group to share the same MCCH notification cycle. In one embodiment, the same MBS services with the same or similar QoS requirement are grouped together. An MBS specific QoS class identifier (QCI) or QoS flow ID (QFI) are defined to express the service or the flow of the service with particular QoS requirement. The MBS services having same or similar QCI or QFI are grouped together to share the same MCCH notification cycle. The negative point of grouping different service together is that it increases the possibility of false alarm, when the UE checks the DCI but there is no modification notification for the MBS services the UE interested in receiving or is receiving. A limitation is determined for MBS service grouping when determining the MCCH notification cycle for the MBS services within a cell. For example, within the configured 2560ms MBS DRX cycle, it assumes there are thirty-two NFs, each with four notification occasions configured. The configurable MCCH notification cycle can be 2560ms, with scaling factor=1; 1280ms, with scaling factor=2; 640ms, with scaling factor=4; 320ms, with scaling factor=8; 160ms, with scaling factor=16; and 80ms, with scaling factor=32. Then these MCCH notification cycles have 32 NFs, 16 NFs, 8 NFs, 4 NFs, 2 NFs or 1 NF respectively. Within this cell, six unique MCCH notification cycles can be configured to different service groups. In each service group, four unique occasion can be assigned to different services when taking full advantage of all the configured notification occasions. The cell can support the MCCH transmission and/or notification without overlapping for up to 24 MBS services. When the cell supports more MBS services, the MCCH transmission and/or notification of multiple MBS services needs to be combined and transmit at the same NF and/or notification occasions. In other embodiment, when the repetition MCCH transmission and/or notification are supported, the MCCH transmission and/or notification of different MBS services to be combined at a given same NF and/or NO may present a larger number than non-repetition case.

Figure 7A illustrates exemplary diagrams of MCCH transmission and/or modification notification in accordance with embodiments of the current invention. In one embodiment, the MCCH transmission and/or notification can be addressed via a new RNTI, such as the MBS RNTI (M-RNTI) . In one embodiment 721, the content of MCCH transmission and/or notification are carried by DCI format 1_0 with CRC scrambled by M-RNTI. As an alternative, the MCCH transmission and/or notification can be addressed by P-RNTI over PDCCH. In another embodiment 722, the MCCH DCI is a new DCI format. MCCH DCI 701 includes one or more elements of 711, 712, 713, 714, 715, and 716. Element 711 is an indicator of an existence of scheduling information for MCCH transmission. Element 712 is an indicator of an existence of scheduling information for MCCH notification. Element 713 is a one-bit indicator of modification of MCCH information. Element 714 is an indicator to indicate the start of a new service and a change of an ongoing service with a different MCCH notification cycle. Element 715 is identity information of one or more MBS service groups. Element 716 is identity information of one or more multicast traffic channels (MTCHs) carried by corresponding MCCH.

The content of the MCCH transmission and/or notification carried by DCI format 1_0 can include short messages indicator (2 bits according to Table 7.3.1.2.1-1 of 3GPP TS38.212) , short messages bits, frequency domain resource assignment, time domain resource assignment, VRB-to-PRB mapping, modulation and coding scheme, TB scaling, and reserved bits. In one embodiment, the short message indicator carries information for element 711 and/or element 712. Within the short messages indicator, the reserved code point “00” is used to indicate that only scheduling information for MCCH transmission and/or notification is present in the DCI, if P-RNTI is used for addressing. Within the short messages indicator, the code points “00” or “01” are used to indicate that only scheduling information for MCCH transmission and/or notification is present in the DCI, if a new M-RNTI is used for addressing. The other code points of short messages indicator are reserved. The short messages bits (eight bits, according to Subclause 6.5 of 3GPP TS38.331) is also reserved as the intention of this DCI is only to deliver MCCH transmission and/or notification. The rest bits including frequency domain resource assignment, time domain resource assignment, VRB-to-PRB mapping, modulation and coding scheme and TB scaling are used to schedule the actual transmission of the content of MCCH over PDSCH. In another embodiment, a new DCI format is used to carry the content of MCCH transmission and/or notification to reduce the reserved bits in DCI format 1_0. When the DCI format 1_0 or a new DCI format is used to carry the content of MCCH transmission and/or notification, the DCI is called MCCH DCI.

In one embodiment, the content of MCCH DCI includes one bit for element 713 to indicate the modification of the MCCH information comparing with last MCCH Notification cycle. This bit can be only toggled at the boundary of MCCH notification cycles. Depending on if this bit is toggled, the UE determines the succeeding reception behavior. The UEs that have already read the same MCCH content will not read the MCCH content again if this bit is not toggled. This applies to the UEs that are interested in MBS reception or are receiving ongoing MBS services. For the UEs that just power on or move to the current cell from neighbor cells, the UEs will read the MCCH content in any case.

In one embodiment, one or more MBS service group identitiesof elements 715 are included in the MCCH DCI to tell the UE (s) which MBS service group (s) is configured by this MCCH. These MBS service group (s) shares this MCCH. UE can skip the reception of the PDSCH if the UE (s) is not inteseted in the MBS services belonging to the MBS service group (s) indicated by this DCI. The length of MBS service group identity is configurable or fixed by network. In another emeobidment, the content of MCCH DCI can include one bit to indicate if there is any MCCH control information scheduled within this MCCH notification cycle. When this bit is transmitted, the UEs receiving this DCI is not expected to decode any follow-up PDSCH transmission for MCCH control information. In yet another embodiment, the content of MCCH DCI includes two bits to indicate the modification of the MCCH. One bit is used to indicate the start of new MBS service for the current MBS service group (s) that shares the same MCCH notification cycle or start of new MBS service for a new MBS service group that shares the same MCCH notification cycle as the current one. The other bit is used to indicate the change of the ongoing MBS services that have the same MCCH notification cycle.

In one embodiment, the content of MCCH DCI includes multiple bits to indicate the modification of the MCCH caused by which MBS service group. MBS service group ID (s) are included to show the modification of the MCCH information for that particular MBS service group (s) . In an embodiment, the content of MCCH DCI can include two bits for element 714 to indicate the modification of the other MCCH that uses different MCCH notification cycle. One bit is used to indicate the start of new MBS service of MBS service group that have different MCCH notification cycle from the current one. The other bit is used to indicate the change of the ongoing MBS services that have different MCCH Notification cycle. In yet another embodiment, element 716, the identity information of MBS service group, and/or the identity information of the MTCH carried by the MCCH is indicated within the MCCH DCI. This helps the UEs to judge if the interested MBS service group or MBS service is scheduled by the follow-up MCCH and this judgement helps the UE to determine if there is a need to futher decode the PDSCH carrying the MCCH in order to anquire the updated information for the interested MBS service (s) or ongoing MBS service (s) . Traditionally, for a particular MTCH, the MCCH carries the identity information of MBS service corresponding to MTCH, scheduling information of MTCH and neighbouring cell information for the MTCH. There are different ways to carry the the identity information of MBS service group, and/or the identity information of the MTCH within the MCCH DCI. One way is to use a bitmap with each bit indicating the scheduing of one MBS service group. Another bitmap is used to indicate the MBS service within the MBS service group. The identities of each MBS service group and the MBS service within each MBS service group are configured by system information at BCCH. For example, in a cell, if there are four MBS service groups each with with 8 MBS services configured. When only the first MBS service group is scheduled, bitmap “1000” or “0001” is used. When only the first two MBS services within the first MBS service group is notified in this MCCH notificaiton DCI, bitmap “10000000” or “00000001” is used.

In certain systems, such as NR system, the UEs in RRC_CONNECTED, RRC_IDLE and RRC_INACTIVE state use Discontinuous Reception (DRX) mode to monitor MCCH DCI in order to reduce power consumption. The UEs obey the MCCH notification cycle of the interested MBS service or the ongoing MBS service. If the UE intends to receive multiple types of MBS service within the same service group, the UE performs DRX reception following only one MCCH notification cycle, corresponding to the MBS service group. If the UE intends to receive multiple types of MBS service within the different service groups, the UE performs DRX reception following more than one MCCH notification cycles. For a particular MCCH notification cycle, the UE monitors one MBS Notification Occasion (NO) per MCCH notification cycle. An MBS notification occasion is a set of PDCCH monitoring occasions and can consist of multiple time slots (e.g. subframe or OFDM symbol) where MCCH DCI can be sent. The PDCCH monitoring occasions for MBS NO follows the same principle as that for legacy paging and are configured at BCCH. One MBSNF is one radio frame and may contain one or multiple MBS notification occasion (s) or starting point of a NO. In multi-beam operations, the UE assumes that the same MCCH DCI is repeated in all transmitted beams and thus the selection of the beam (s) for the reception of the MCCH DCI is up to UE implementation.

In one embodiment, the MBS notification NF is determined by an NF_offset that is determined by a system frame number (SFN) and a MCCH notification cycle T, and wherein T is determined by a number N of total NFs in an MBS DRX cycle and the scaling factor S. In another embodiment, when a repetition cycle R and a repetition factor M is configured for MBS notification repetition, and wherein the MBS notification NF is determined further based on the repetition cycle R and the repetition factor M. In one embodiment, the MBS notification occasion is determined by a group ID and a number Ns of MBS notification occasions for an MBS NF, and wherein the Ns is signaled in a broadcast control channel (BCCH) and the group ID is an identity of corresponding MBS service group.

The MBS NF and notification occasion are determined by the following formulas. SFN for the NF is determined by: SFN mod T=NF_offset. NF_offset is the offset used for NF determination and the unit of NF_offset is one radio frame. T is the MCCH notification cycle of the MBS service or MBS service group. T is determined by: T=N div S. N is the number of total NFs within an MBS DRX cycle in the cell. S is the scaling factor for MCCH notification cycle within the MBS DRX cycle. It means that the value T is determined by scaling factor of the MBS service or MBS service group and the number of total NFs within an MBS DRX cycle. The values N and NF_offset are configured via BCCH. When repetition cycle and repetition factor are configured for MCCH repeated transmission, the repetition SFN for the NF is determined by: SFN mod T=NF_offset+m*R. R is the repetition cycle of the MBS service or MBS service group. Repetition cycle can be configured by RRC layer in system information. The integer n includes all the integers within the set {0, 1, …, M} , where M is the configured repetition factor of the MBS service or MBS service group. T is determined by: T=N div S, which follows the same principle as for non-repetition case. Index (i_s) , indicating the index of the NO is determined by: i_s=Group_ID mod Ns. Ns is the number of notification occasions for a NF. Parameter Ns is signaled in BCCH. Group_ID can be the identity of the MBS service group. Alternatively, the identity of the first MBS service within the MBS service group can be used as Group ID in the formula. When repetition is configured for a particular MCCH transmission, the same notification occasion is used in the repeated NF as the initial transmission NF.

Figure 7B illustrates exemplary diagrams for MBS specific SIB carrying MCCH information in accordance with embodiments of the current invention. In the NR network, the MBS related control information is transmitted by MCCH. A limited amount of MBS control information is provided on the BCCH. This primarily concerns the information needed to acquire the MCCH. The MCCH information (i.e. information transmitted in messages sent over MCCH) is transmitted periodically, using a configurable MCCH notification cycle. The MCCH may be repeated with a repetition cycle within the MCCH notification cycle.

A new SIB, the MBS specific SIB 702, is defined to carry MCCH information. MBS specific SIB 701contains the information required to acquire the control information associated with the transmission of MBS service (s) . This SIB contains the cell specific MBS DRX configuration 781 and one or more MBS service 782 or MBS service group 783. The cell specific MBS DRX configuration 781 includes one or more elements comprising an MBS DRX cycle, a number of notification frames with corresponding DRX cycle, a frame offset, a number of notification occasions within each notification frame, and a first physical downlink control channel (PDCCH) monitoring occasion for each notification occasion of corresponding notification frame. Within this SIB, a list of MBS service group 783 is included. For each MBS service group, one or more elements comprising an MBS service group identity, an MCCH notification cycle, corresponding MCCH logical channel ID (LCID) , and optionally, an MCCH repetition cycle, and a repetition factor. A cell may support one or more MCCH channels. Each MCCH logical channel has a unique MCCH notification cycle. Each MCCH is responsible for the transmission of the MBS control information of one or more MBS service groups. In one embodiment, within the MBS specific SIB, a list of MBS service is included. For each MBS service, one or any combination of the information elements of MBS Service identity 784, MBS scaling factor (or MCCH notification cycle) , and corresponding MCCH LCID. Optionally, the MCCH repetition cycle and repetition factor are also included for each MBS Service. The MBS Service identity can be the MBS session ID, the list of the MTCHs 785, or an index of the supported MBS service within the cell. The BCCH provides the overview of all the MBS services or MBS service groups transmitted or to be transmitted in the cell. The MCCH provides a full or subset of the information of the MBS services or MBS service groups in the MCCH notification cycle. However, looking at the whole MBS DRX cycle, a full set of the information of the MBS services or MBS service groups is provisioned by the MCCHs. In the MCCH notification cycle, the MCCH provides the configuration of a list of MBS service groups. The MCCH also provides a list of neighbour cells providing MBS services. For each MBS service group, the MBS service group ID, and a list of MTCH are provided. For each MTCH, MBS session information, G-RNTI and MTCH scheduling information are included. Optionally, for each MTCH, a local index is provided to express the sequential number of the MBS service within current MBS service group. This index can be used to form the bitmap for purpose of modification notification in MCCH DCI. For example, if the current MBS service group has eight MBS services in transmission, the value range of the local index is the integer of the set {0, 1, …, 7} . As an alternative, no MBS service group information is provided, only MBS service-related information is provided in MCCH.

Figure 8 illustrates an exemplary procedure for MCCH control information transmission in accordance with embodiments of the current invention. UE 801 receives multicast services from the NR network via gNB 802. At step 811, SIB1 schedules the MBS specific SIB for MBS transmission. According to the SIB1 scheduling, UE 801 can read the MBS specific SIB. At step 821, gNB 802 sends the MBS specific broadcast. UE 801 finds interested MBS service group or MBS service, determines the exact NF/notification occasion and MCCH notification cycle to monitor the corresponding MCCH DCI for the MBS service group or MBS service. Optionally the repetition cycle and repetition factor are used by UE 801 to find the closest upcoming MCCH transmission. At step 831, gNB 802 sends MCCH scheduling in MCCH notification cycle. The relevant MCCH control information is scheduled by the network following the configured MCCH notification cycle (and MCCH Repetition cycle) in a notification frame. UE 801 monitors the notification frame and notification occasion according to the local calculation and decodes the MCCH DCI by M-RNTI. After decoding the DCI, UE 801 decodes the corresponding PDSCH to read the MCCH to get the scheduling information of the MBS service that UE 801 is interested. The transmission of MCCH is carried by a single transport block (TB) . One-shot transmission is used for the MCCH. In one embodiment, the transmission of MCCH is carried by multiple TBs. UE 801 needs to keep monitoring the PDCCH after the reception of the first PDSCH for the first TB. In this case, the legacy On-Duration-Timer, DRX-Inactivity-Timer, and Scheduling-Period-Start-Offset may be configured by BCCH for this MCCH. UE 801 needs to monitor the PDCCH until finish reception of all the TBs for MCCH.

At step 841, gNB 802 transmits MTCH scheduling. The relevant MTCH transmission is scheduled by the network based on the configured MTCH scheduling information as acquired by the UE 801. UE 801 receives the MTCH transmission, which is transmitted in multicast or broadcast manner. At step 842, UE 801 periodically checks the MCCH DCI in the boundary of MCCH notification cycle. When there is no modification indicated in the DCI, UE 801 skips the reception of the MCCH scheduled by the DCI. In one embodiment, some modifications for other MBS services or MBS service groups are also included in the current MCCH DCI. At step 843, the MTCH transmission scheduled by the network is the same as step 841, as there is no modification. At step 851, gNB 802 send MCCH modification in MCCH notification cycle. The network broadcasts the MCCH modification indicator (i.e. change notification) within the MCCH DCI in the boundary of MCCH notification cycle. At step 852, UE 801 decodes the MCCH DCI, finds there is indication for the modification of the MCCH control information, and then decodes the PDSCH carrying the updated MCCH control information. At step 861, gNB 802 sends new MTCH scheduling. The relevant MTCH transmission is scheduled by the network for the updated MTCH scheduling information as acquired by the UE in step 852.

Figure 9 illustrates an exemplary flow chart for the control information scheduling and modification notification for multicast and broadcast in accordance with embodiments of the current invention. At step 901, the UE configures a plurality of multicast broadcast services (MBSs) , wherein control information for the plurality of MBSs are received on multiple multicast control channels (MCCHs) each with an independent MCCH notification cycle. At step 902, the UE receives an MBS configuration of MCCH notification for the configured MBSs. At step 903, the UE monitors MCCH notifications for each corresponding configured MCCH notification based on the MBS configuration, wherein each MCCH notification cycle is based on a scaling of cell-specific MBS DRX cycle associated with a scaling factor S. At step 904, the UE receives the plurality of MBSs based on detected plurality of MCCH notifications for corresponding MBSs.

Although the present invention has been described in connection with certain specific embodiments for instructional purposes, the present invention is not limited thereto. Accordingly, various modifications, adaptations, and combinations of various features of the described embodiments can be practiced without departing from the scope of the invention as set forth in the claims.

Claims

A method comprising:

configuring, by a user equipment (UE) , a plurality of multicast broadcast services (MBSs) , wherein control information for the plurality of MBSs are received on multiple multicast control channels (MCCHs) each with an independent MCCH notification cycle;

receiving an MBS configuration of MCCH notification for the configured MBSs;

monitoring MCCH notifications for each corresponding configured MCCH notification based on the MBS configuration, wherein each MCCH notification cycle is based on a scaling of cell-specific MBS DRX cycle associated with a scaling factor S;

receiving the plurality of MBSs based on detected plurality of MCCH notifications for corresponding MBSs.
The method of claim 1, wherein MCCH notification information is carried by an MCCH DCI with cyclic redundant check (CRC) scrambled by multimedia broadcast multicast services (MBMS) radio network temporary identifier (M-RNTI) .
The method of claim 2, wherein the MCCH DCI includes one or more MCCH elements comprising an indicator of an existence of scheduling information for MCCH transmission, an indicator of an existence of scheduling information for MCCH notification, a one-bit indicator of modification of MCCH information, and an indicator to indicate the start of a new service and a change of an ongoing service with a different MCCH notification cycle.
The method of claim 2, wherein the MCCH DCI includes one or more elements comprising identity information of one or more MBS service groups and identity information of one or more multicast traffic channels (MTCHs) carried by corresponding MCCH.
The method of claim 1, wherein the MBS configuration includes an allocation of a resource pool for MBS control information and notification reception.
The method of claim 5, wherein the resource pool is configured with a plurality of MBS notification frames (NFs) for corresponding MBS or MBS service groups.
The method of claim 6, wherein the MBS notification NF is determined by an NF_offset that is determined by a system frame number (SFN) and a MCCH notification cycle T, and wherein T is determined by a number N of total NFs in an MBS DRX cycle and the scaling factor S.
The method of claim 7, wherein a repetition cycle R and a repetition factor M is configured for MBS notification repetition, and wherein the MBS notification NF is determined further based on the repetition cycle R and the repetition factor M.
The method of claim 6, wherein each MBS NF is configured with one or more MBS notification occasions.
The method of claim 9, wherein the MBS notification occasion is determined by a group ID and a number Ns of MBS notification occasions for an MBS NF, and wherein the Ns is signaled in a broadcast control channel (BCCH) and the group ID is an identity of corresponding MBS service group.
The method of claim 1, wherein the MBS configuration includes MBS parameters for MCCH reception for MBS services, and wherein the MBS parameters for MCCH reception for MBS services are received on an MBS specific system information block (SIB) .
The method of claim 11, wherein the MBS specific SIB carries MCCH information includes one or more elements comprising a cell specific MBS DRX configuration, one or more MBS services, and one or more MBS service groups.
The method of claim 12, wherein the cell specific MBS DRX configuration includes one or more elements comprising an MBS DRX cycle, a number of notification frames with corresponding DRX cycle, a frame offset, a number of notification occasions within each notification frame, and a first physical downlink control channel (PDCCH) monitoring occasion for each notification occasion of corresponding notification frame.
The method of claim 12, wherein the MBS service group includes one or more elements comprising an MBS service group identity, an MCCH notification cycle, corresponding MCCH logical channel ID (LCID) , an MCCH repetition cycle, and a repetition factor.
The method of claim 12, wherein the MCCH information further includes one or more MBS service group IDs and a list of MTCHs.
The method of claim 15, wherein the list of MTCHs includes a local index for each MTCH indicating a sequential number for corresponding MBS service within the MBS service group.
A user equipment (UE) , comprising:

a transceiver that transmits and receives radio frequency (RF) signal in a new radio (NR) wireless network;

a configuration module that configures a plurality of multicast broadcast services (MBSs) , wherein control information for the plurality of MBSs are received on multiple multicast control channels (MCCHs) each with an independent MCCH notification cycle;

an MBS notification module that receives an MBS configuration of MCCH notification for the configured MBSs;

a monitor module that monitors MCCH notifications for each corresponding configured MCCH notification based on the MBS configuration, wherein each MCCH notification cycle is based on a scaling of cell-specific MBS DRX cycle associated with a scaling factor S;

an MBS receiver that receives the plurality of MBSs based on detected plurality of MCCH notifications for corresponding MBSs.
The UE of claim 17, wherein MCCH notification information is carried by an MCCH DCI with cyclic redundant check (CRC) scrambled by multimedia broadcast multicast services (MBMS) radio network temporary identifier (M-RNTI) .
The UE of claim 17, the MBS configuration includes an allocation of a resource pool for MBS control information and notification reception.
The UE of claim 17, the MBS configuration includes MBS parameters for MCCH reception for MBS services.