Multiuser MIMO Scheduling via Adaptive Terminal Grouping
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Solution Overview
Problem
In Multiple Input Multiple Output (MIMO) communication systems with multiple user terminals, existing methods face challenges in maximizing multiplexing gain and reducing inter-user interference due to limited channel information and increasing interference with the number of user terminals, leading to suboptimal throughput.
Innovation Solution
A method and apparatus for adaptively scheduling multiuser terminals by determining the optimal number based on average Signal to Noise Ratio (SNR) and grouping user terminals with similar SNR, using a subset of random precoding vectors to maximize throughput and reduce inter-user interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of multiuser terminals is increased to maximize multiplexing gain, then throughput is improved, but inter-user interference increases causing throughput degradation
Solution Approach 1:
The invention dynamically adjusts the number of multiuser terminals based on channel conditions and interference levels. By changing the parameter of user terminal count adaptively rather than fixing it, the system optimizes the balance between multiplexing gain and interference management, resolving the contradiction between maximizing throughput and controlling inter-user interference.
Solution Approach 2:
The system transitions from static user terminal selection to dynamic scheduling where the number and composition of multiuser terminals changes based on real-time channel state information. This dynamic approach allows the system to exploit favorable channel conditions while avoiding situations where interference would degrade performance, thus resolving the throughput-interference tradeoff.
2Productivity
If all transmit antennas are used for multiplexing channels, then multiplexing gain is maximized, but the number of user terminals needed increases exponentially
Solution Approach 1:
Instead of requiring all user terminals to be simultaneously multiplexed with all transmit antennas, the invention applies partial action by selecting a subset of user terminals for multiplexing based on channel conditions. This partial multiplexing approach achieves significant multiplexing gain without requiring the exponential increase in user terminals that would be needed for complete antenna utilization.
3Device complexity
If the number of user terminals is limited in real-world environments, then system complexity is reduced, but it becomes difficult to find sufficient user terminals to avoid inter-user interference
Solution Approach 1:
The invention implements feedback mechanisms where channel state information is collected from user terminals and used to make intelligent scheduling decisions. This feedback enables the base station to identify combinations of user terminals that minimize inter-user interference, resolving the contradiction between limited user terminal availability and interference avoidance in realistic system complexity constraints.
Data Source
AI summary
A method and apparatus for scheduling multiuser terminals in a communication system is provided. A receiver receives feedback information from a plurality of user terminals. A user grouping unit selects terminals having a maximum Signal to Interference plus Noise Ratio (SINR) among terminals having the same beam index and beam subset index, from among the plurality of user terminals, and generates terminal groups using the selected terminals, each terminal group including terminals having the same beam subset index. A group scheduling unit calculates a throughput of each of the terminal groups to determine which terminal group has the maximum throughput. A random precoding unit generates random beam vectors corresponding to terminals included in the terminal group determined to have the maximum throughput, and transmits data for user terminals, included in the terminal group determined to have the maximum throughput, over the generated random beam vectors.