MU-MIMO Downlink Scheduling with Decoupled ARQ Rate Control
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Solution Overview
Problem
In wireless cellular systems, the uncertainty in signal, noise, and interference levels affects the efficiency of user-scheduling and MU-MIMO downlink signaling, leading to transmission outages and suboptimal resource utilization due to unknown inter-cell interference and channel conditions.
Innovation Solution
A method that decouples ARQ protocol parameters from scheduling decisions, allowing for independent optimization of ARQ blocks and user terminal scheduling weights based on estimated channel quality and application constraints, using a processing unit to update scheduling weights and generate precoded data for MIMO transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the maximum transmission rate is determined based on estimated channel conditions, then the scheduling efficiency is improved, but the reliability of transmission deteriorates due to uncertainty in signal, noise, and interference levels
Solution Approach 1:
The patent applies preliminary action by generating multiple ARQ blocks in advance before the actual transmission scheduling decision is made. These pre-generated blocks are stored and can be selectively transmitted based on actual channel conditions, allowing the system to prepare multiple rate options ahead of time without committing to a single potentially suboptimal rate decision
Solution Approach 2:
The patent changes the parameter of transmission rate by providing multiple ARQ blocks with different coding rates. Instead of using a single fixed rate based on estimated conditions, the system transmits multiple blocks with varying rates (e.g., different code rates like 1/2, 2/3, 3/4) to adapt to the actual channel quality, thereby resolving the contradiction between scheduling efficiency and transmission reliability
2Productivity
If ARQ parameters are coupled with scheduling decisions, then the system can optimize for each user individually, but the system complexity increases
Solution Approach 1:
The patent applies segmentation by separating the ARQ block generation process from the scheduling decision process. The ARQ blocks are generated independently of scheduling based on channel quality distributions, while the scheduler simply selects which pre-generated blocks to transmit. This decoupling reduces system complexity while maintaining user-specific optimization capabilities
Solution Approach 2:
By generating ARQ blocks in advance (preliminary action) independent of scheduling decisions, the system prepares all necessary transmission blocks beforehand. The scheduling process then becomes simpler, only needing to select from the pre-generated blocks based on current channel conditions, thereby reducing the complexity of joint optimization
3Productivity
If the transmission rate is increased to approach maximum sum throughput, then the productivity is improved, but the decoding delay increases
Solution Approach 1:
The patent applies dynamics by enabling the system to dynamically adjust the effective transmission rate through selective transmission of ARQ blocks with different coding rates. Based on actual channel conditions and quality distributions, the system can choose to transmit higher rate blocks when conditions are good (increasing throughput) or use lower rate blocks when conditions are poor (reducing delay), thus dynamically balancing throughput and delay
Data Source
AI summary
A method and apparatus is disclosed herein for performing wireless communication. In one embodiment, the apparatus comprises a processing unit to run a scheduling selection algorithm to update user terminal scheduling weights in response to scheduling feedback transmitted by a plurality of user terminals by an end of an immediately preceding scheduling event; a scheduler and precoder, responsive to the updated user terminal scheduling weights generated by the scheduling algorithm and channel estimates of user terminals, to choose a set of user terminals for scheduling and to choose precoder beams and their power for such user terminal in the set of user terminals; a plurality of precoding blocks to receive one coded ARQ block for at least one packet for each user terminal in the set and, responsive to the precoder beams, to generate precoded data, where the one coded ARQ block is one of a plurality of ARQ blocks generated for a single packet and being generated using a single ARQ scheme for such each user terminal; and a transmitter to transmit the precoded data using MIMO transmission.