SPS PMI Notification for Closed-Loop MIMO
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Solution Overview
Problem
Current LTE systems limit semi-persistent scheduling to only support transmit diversity and single antenna port transmission modes due to the unavailability of precoding matrix indicators (PMI) for spatial multiplexing, resulting in suboptimal transmission performance.
Innovation Solution
A method and device that dynamically notify terminals of the required PMI for closed loop spatial multiplexing MIMO transmission mode, allowing the terminal to use the latest PMI for data transmission, and group terminals to multicast PMIs, reducing signaling overhead and enabling support for closed loop spatial multiplexing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If semi-persistent scheduling is implemented without PDCCH grants for subsequent transmissions, then signaling load is reduced, but precoding matrix indicator (PMI) becomes unavailable for spatial multiplexing
Solution Approach 1:
The base station performs preliminary action by sending PMI information through the initial PDCCH grant when the SPS service is activated. This preliminary transmission of PMI allows the terminal to have the necessary precoding information available for subsequent SPS transmissions without requiring continuous PDCCH grants, thus resolving the contradiction between reduced signaling load and maintained PMI availability.
2Productivity
If closed loop spatial multiplexing is supported in SPS mode, then transmission performance is improved, but PDCCH signaling overhead increases due to PMI notification requirements
Solution Approach 1:
The base station transmits PMI information in advance through the initial PDCCH grant, enabling the terminal to perform closed loop spatial multiplexing without requiring continuous PMI updates via PDCCH signaling during the SPS transmission period, thus improving transmission performance while avoiding excessive signaling overhead.
Solution Approach 2:
The terminal feeds back PMI information to the base station through the initial PDCCH grant, allowing the base station to configure appropriate precoding matrices for subsequent SPS transmissions. This feedback mechanism enables closed loop spatial multiplexing while minimizing ongoing signaling requirements.
3Adaptability or versatility
If dynamic PMI notification is implemented for SPS terminals, then closed loop spatial multiplexing is enabled, but control channel resources are consumed
Solution Approach 1:
The base station performs preliminary action by including PMI information in the initial PDCCH grant that activates the SPS service. This one-time preliminary transmission of PMI enables the terminal to support multiple MIMO transmission modes including closed loop spatial multiplexing without consuming continuous control channel resources during the SPS transmission period.
Data Source
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AI summary
The present invention discloses a method and device for realizing a semi-persistent scheduling or semi-persistent scheduling-like service. The method includes: notifying a terminal of its SPS or SPS-like period, so that the terminal sends SPS service or SPS-like service data according to the period and by adopting a transmission mode with a closed loop rank 1; dynamically notifying the terminal of a precoding matrix indicator PMI required for its SPS or SPS-like service to support the transmission mode with the closed loop rank 1, so that the terminal uses a latest received PMI when sending the SPS service or SPS-like service data; and receiving, by a base station and based on the transmission mode with the closed loop rank 1, the SPS service or SPS-like service data sent by the terminal. Through the present invention, the SPS or SPS-like service can support a MIMO transmission mode with the closed loop rank 1.