MBSFN Subframe Configuration for MBMS Information Delivery
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Solution Overview
Problem
In LTE wireless communication systems, user equipment (UE) faces challenges in receiving multicast broadcast single frequency network (MBSFN) subframes, particularly when secondary cells (S-cells) transmit MBMS-related information without a defined common search space for PDCCH and PBCH, making it difficult for UEs to obtain necessary system information, especially in RRC_IDLE state.
Innovation Solution
The method involves transmitting MBMS-related information through an NCT subframe configured as an MBSFN subframe, using an enhanced PDCCH (EPDCCH) or a common search space (CSS) defined in the NCT subframe, and employing a new carrier type (NCT) reference signal (NCT-CRS) to support MBMS services, allowing UEs to receive MBMS change information even in RRC_IDLE state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If S-cells transmit MBMS-related information without a defined common search space for PDCCH and PBCH, then spectral efficiency is improved, but UEs cannot obtain necessary system information especially in RRC_IDLE state
Solution Approach 1:
The patent introduces an MBSFN subframe as an intermediary structure that carries MBMS-related information. This MBSFN subframe includes a PMCH (Physical Multicast Channel) that can transmit system information to UEs in RRC_IDLE state, thereby mediating between the need for spectral efficiency and the need for information delivery. The MBSFN configuration acts as a bridge that allows S-cells to transmit MBMS information without requiring traditional PDCCH/PBCH common search spaces.
2Loss of information
If UEs monitor MCCH change notification for all MBSFN areas, then complete MBMS information is received, but device complexity and power consumption increase
Solution Approach 1:
The patent segments the MBMS information reception process by introducing area-specific MBSFN configurations. Instead of requiring UEs to monitor all MBSFN areas uniformly, the system divides MBSFN areas into distinct configurations, allowing UEs to selectively monitor only relevant areas based on their service requirements. This segmentation reduces the overall monitoring burden and device complexity while ensuring complete reception of necessary MBMS information.
Solution Approach 2:
The patent applies local quality by allowing different MBSFN areas to have different configuration characteristics. Each MBSFN area can be configured with specific parameters such as subframe allocations, PMCH configurations, and MCCH settings tailored to local requirements. This enables UEs to adapt their monitoring behavior to local area characteristics rather than applying a uniform monitoring strategy across all areas, thereby reducing overall complexity.
3Device complexity
If UEs are aware of PMCH configuration of only one MBSFN area when interested session is started, then device complexity is reduced, but UEs cannot know PMCH configuration of other MBSFN areas
Solution Approach 1:
The patent implements preliminary action by pre-configuring MBSFN area information in system information blocks (SIBs) that are available to UEs in RRC_IDLE state. This preliminary configuration includes MBSFN area identifiers, subframe allocations, and PMCH configuration parameters. When UEs become interested in MBMS services, they already possess basic configuration knowledge for multiple MBSFN areas, eliminating the need for complex on-demand configuration acquisition and enhancing adaptability without significantly increasing device complexity.
Data Source
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AI summary
Disclosed is a method for transmitting a multicast broadcast single frequency network (MBSFN) subframe, including: configuring, by a base station (BS), at least one subframe, among a plurality of subframes included in a downlink radio frame, to an MBSFN subframe; determining, by the BS, resource allocation with respect to a tracking reference signal in the at least one configured MBSFN subframe based on whether a physical multicast channel is transmitted in the at least one configured MBSFN subframe; and transmitting, by the BS, the tracking reference signal through an MBSFN subframe in which the PMCH is not transmitted among the at least one configured MBSFN subframe.