Multicast Window Adjustment for NR Transmission Reliability
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Solution Overview
Problem
The New Radio (NR) system lacks a feedback mechanism for multicast scenarios in multimedia broadcast multicast service (MBMS), resulting in unreliable transmission of MBMS services, as terminal devices do not receive feedback, and thus, the transmission reliability of MBMS services cannot be guaranteed.
Innovation Solution
Implementing a window adjustment method that includes determining sending parameters for data packets and moving send and receive windows based on acknowledgment (ACK) or negative acknowledgment (NACK) feedback, enabling retransmission of packets and ensuring accurate receipt by terminal devices, thereby introducing RLC or PDCP feedback mechanisms in multicast scenarios to enhance transmission reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a feedback mechanism is introduced in multicast scenario, then transmission reliability is improved, but device complexity increases
Solution Approach 1:
The patent implements an ARQ feedback mechanism where terminal devices send ACK/NACK feedback to the network device for multicast data packets. The network device adjusts its transmission based on this feedback, sending retransmissions only when NACK is received, thereby improving transmission reliability through structured feedback loops.
Solution Approach 2:
The send window and receive window are dynamically adjusted based on feedback from terminal devices. The network device moves the send window forward when ACK is confirmed, and terminal devices adjust their receive windows based on received packets and feedback, creating a dynamic adaptation mechanism that improves reliability without static complexity.
2Productivity
If window adjustment mechanism is implemented, then transmission efficiency is improved, but control complexity increases
Solution Approach 1:
The network device pre-configures the send window with multiple data packets before transmission begins. Terminal devices pre-configure their receive windows to match the expected packet range. This preliminary setup enables efficient batch transmission and reduces per-packet control overhead, improving transmission efficiency while managing control complexity.
Solution Approach 2:
Terminal devices autonomously manage their own receive windows and generate feedback messages based on locally received packets. The network device autonomously adjusts its send window based on received feedback without requiring centralized coordination for each packet, enabling self-service operation that improves efficiency while distributing control complexity.
Data Source
AI summary
A window adjustment method and apparatus, a network device and a terminal device, the method comprising: a network device determining a first sending parameter, the first sending parameter being used to indicate an SN of a first data packet, and sending the first data packet according to the first sending parameter, the first data packet being a next data packet expected to be sent in a send window (501); if the network device confirms that the first data packet has been accurately received by at least one terminal device, the network device moving the send window; a starting SN of the send window before being moved being a first SN, a starting SN of the send window after being moved being a second SN, and the second SN being a first unconfirmed SN after the first SN (502).