Beamformed Sounding for Spatially Compatible User Scheduling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing multi-antenna wireless communication systems face challenges in determining spatial compatibility among users to avoid interference when scheduling multiple users on the same time and frequency resource, particularly in TDD retro-directive beamforming systems with dynamic allocations in time, frequency, and space.
Innovation Solution
The system determines spatial compatibility by transmitting beamformed sounding signals and receiving feedback data to calculate a compatibility metric, using signal strength and signal-to-interference data to schedule users on the same time-frequency resource, and computes transmit weights based on receive weights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple users are scheduled on the same time and frequency resource, then system productivity increases, but interference between users increases
Solution Approach 1:
The patent applies local quality by determining spatial compatibility metrics for different user pairs and applying interference cancellation specifically to identified incompatible users. The system calculates compatibility metrics based on channel characteristics and selectively applies interference cancellation techniques only where needed, rather than uniformly across all users, thus improving throughput while managing interference locally.
Solution Approach 2:
The patent converts harmful interference into a beneficial signal processing task by using interference cancellation techniques. The receiver deliberately decodes both the desired signal and interfering signals, then subtracts the decoded interference from the received signal to recover the desired signal with improved quality. This transforms the harmful effect of interference into an opportunity for enhanced signal processing and throughput.
2Measurement precision
If transmit weights are optimized for spatial multiplexing, then signal quality improves, but calculation complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating spatial compatibility metrics and identifying incompatible user pairs before scheduling decisions are made. The system determines compatibility metrics based on channel characteristics in advance, allowing the scheduler to make informed decisions without performing complex real-time calculations during the scheduling process itself.
Solution Approach 2:
The patent segments the complex weight optimization problem into manageable steps: first determining spatial compatibility metrics for user pairs, then identifying incompatible users, and finally applying interference cancellation. This segmentation breaks down the overall complexity into distinct, manageable tasks that can be processed sequentially rather than as a single complex optimization problem.
3Measurement precision
If channel sounding is performed to obtain spatial information, then spatial compatibility determination improves, but loss of time increases
Solution Approach 1:
The patent applies universality by designing the channel sounding procedure to serve multiple purposes simultaneously: it obtains channel characteristics needed for spatial compatibility determination while also providing information for beamforming and other signal processing functions. The same sounding signals and received data are reused across different processing tasks, reducing the overall time required compared to performing separate measurements for each function.
Data Source
AI summary
Systems and methods for spatial compatibility determination and weight determination include a base node transmitting a sequence of beamformed sounding signals to a plurality of nodes including at least two nodes; receiving, responsive to the sequence and at the base node, receive signal strength data and signal to interference data for each node of the plurality of nodes; and, calculating, at the base node, a compatibility metric for the at least two nodes. Scheduling the at least two nodes to use a same time-frequency resource based on the compatibility metric and, and transmitting signals using the same time-frequency resource to the at least two nodes, is described. Determining initial downlink and uplink payload transmit weights from the sequence of transmit beamforming sequences is described. Calculating a per-user transmit weight for a base station is also described. Predicting the expected channel quality, pathloss, and selection of signal modulation is described.