SC-PTM Multicast for Narrowband IoT via MPDCCH Segmentation
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Solution Overview
Problem
Current cellular network technologies face challenges in efficiently supporting a massive number of low complexity Machine-Type Communications (MTC) devices, particularly in terms of bandwidth, power consumption, and latency, especially in Single-Cell Point-To-Multipoint (SC-PTM) environments, where existing solutions do not adequately optimize for low complexity Bandwidth Reduced (BR) and Narrowband (NB) User Equipment (UEs).
Innovation Solution
The implementation of techniques that enable the use of MTC Physical Downlink Control Channel (MPDCCH) and Narrowband PDCCH (NPDCCH) in SC-PTM environments, allowing for dynamic adjustment of broadcast/multicast services and optimized multicast scheduling, which includes modifying the configuration of the Single-Cell Multicast Control Channel (SC-MCCH) and Traffic Channel (SC-MTCH) to accommodate the specific needs of BR and NB UEs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If eMBMS synchronized multi-eNB transmission is used, then coverage and reliability are improved, but device complexity and synchronization requirements increase
Solution Approach 1:
The patent segments the multicast service into two independent parts: control plane (SC-MCCH) and user plane (SC-MTCH). The control plane uses dedicated MPDCCH/NPDCCH for reliable delivery to BL/NB UEs, while the user plane uses PTM transmission. This segmentation allows each part to be optimized independently, reducing overall system complexity while maintaining reliability.
Solution Approach 2:
The patent introduces an intermediary mechanism where the SC-MCCH control channel acts as a mediator between the network and BL/NB UEs. The control channel carries scheduling information and configuration parameters that enable UEs to efficiently receive multicast data without requiring complex synchronization, thus simplifying the overall system while maintaining reliability.
2Productivity
If standard LTE bandwidth is allocated to all UEs, then system capacity is maintained, but power consumption and device complexity increase for low complexity UEs
Solution Approach 1:
The patent applies local quality by allocating different bandwidth resources to different UE types. BL/NB UEs are allocated narrowband resources (180 kHz) only when needed for multicast reception, while other UEs continue to use standard LTE bandwidth. This localized resource allocation reduces power consumption for narrowband UEs without impacting overall system capacity.
Solution Approach 2:
The patent implements periodic action through discontinuous reception (DRX) mechanisms and periodic scheduling of SC-MTCH transmissions. BL/NB UEs wake up periodically to receive control information on SC-MCCH and then receive data on SC-MTCH only during scheduled intervals, significantly reducing power consumption while maintaining system capacity utilization.
3Productivity
If SC-PTM uses eMBMS system architecture, then resource utilization is improved, but adaptability to low complexity UEs deteriorates
Solution Approach 1:
The patent introduces dynamics by making the SC-PTM system adaptable to different UE capabilities. The control plane uses dynamic scheduling information carried on MPDCCH/NPDCCH that can be customized for BL/NB UEs, allowing the system to dynamically adjust resource allocation and transmission parameters based on UE type, thereby maintaining resource utilization while improving adaptability.
Solution Approach 2:
The patent applies parameter changes by modifying key system parameters for BL/NB UE support, including using narrowband frequency resources, adjusting timing configurations, and changing modulation and coding schemes. These parameter changes enable the eMBMS-based SC-PTM architecture to accommodate low complexity UEs without sacrificing resource utilization efficiency.
4Area of stationary object
If multicast services are broadcast to all UEs, then service coverage is maximized, but bandwidth efficiency deteriorates for specific target groups
Solution Approach 1:
The patent segments multicast service delivery into control plane (SC-MCCH) and user plane (SC-MTCH), with further segmentation by UE type. Control information is separately addressed to BL/NB UEs using UE-specific RNTI scrambling, while data transmission uses group-based addressing. This segmentation enables targeted delivery that maximizes coverage for specific groups while optimizing bandwidth efficiency.
Solution Approach 2:
The patent implements partial action by transmitting control information only to the intended target group (BL/NB UEs) rather than all UEs. The SC-MCCH uses CRC scrambling with UE-specific RNTI values, so only targeted UEs can decode and process the control information, reducing unnecessary bandwidth consumption by other UEs while maintaining full service coverage for the target group.
Data Source
AI summary
Support of Single-Cell Point-To-Multipoint (SC-PTM) for narrowband (UEs) and low complexity (BL) UEs can is implemented at both the physical layers and the higher layers. For example, in one implementation, a UE may transmit, to a Single-Cell Point-To-Multipoint (SC-PTM) base station, multicast service preference information, including at least one of a Coverage Enhancement (CE) mode or a maximum Transport Block Size (TBS) of the UE. The UE may also monitor a common search space (CSS) of a MTC Physical Downlink Control Channel (MPDCCH) or Narrowband Physical Data Control Channel (NPDCCH) for the scheduling of a Physical Downlink Shared Channel (PDSCH) or a Narrowband Physical Downlink Shared Channel (NPDSCH), respectively, to obtain downlink control information (DCI) that includes configuration information relating to a Single-Cell Multicast Control Channel (SC-MCCH).