Base Station Terminal Selection for MU-MIMO Channel Measurement
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Solution Overview
Problem
Existing MU-MIMO wireless communication systems face challenges in managing uplink traffic and processing load due to the transmission of reference symbols from multiple terminals to a base station, limiting the number of spatial multiplexes and increasing processing burdens on the base station.
Innovation Solution
A base station and terminal system that determines a subset of terminals to transmit reference symbols and select terminals for spatial multiplexing based on channel state information, reducing unnecessary reference symbol transmissions and processing loads by limiting the number of terminals involved in each data transmission cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all connected terminals transmit reference symbols at every data transmission cycle, then the base station can measure channel state information for all terminals, but the uplink traffic increases enormously and the processing load on the base station increases
Solution Approach 1:
The patent segments the set of all connected terminals into multiple groups, where only one group transmits reference symbols at a time. This segmentation allows the base station to measure channel state information for a subset of terminals in each data transmission cycle, thereby reducing the overall uplink traffic volume while maintaining comprehensive measurement coverage across all terminals over multiple cycles.
Solution Approach 2:
The patent implements periodic action by rotating different groups of terminals to transmit reference symbols in alternating data transmission cycles. This periodic rotation ensures that all terminals are measured over time while distributing the uplink traffic load evenly across cycles, preventing any single cycle from being overwhelmed by simultaneous reference symbol transmissions from all terminals.
2Measurement precision
If all connected terminals transmit reference symbols at every data transmission cycle, then the base station can measure channel state information for all terminals, but the processing load on the base station increases
Solution Approach 1:
The patent segments the measurement process into multiple phases, where each phase handles a specific group of terminals. By dividing the total set of P terminals into multiple smaller groups and measuring them sequentially rather than simultaneously, the base station's processing load in each data transmission cycle is significantly reduced, making the system scalable to support a larger number of connected terminals.
Solution Approach 2:
The patent employs periodic action by systematically rotating through different terminal groups across data transmission cycles. This periodic measurement approach distributes the computational burden of channel state information processing over multiple cycles, preventing any single cycle from requiring excessive processing power while ensuring all terminals are eventually measured.
3Productivity
If the base station communicates with only M terminals at maximum per data transmission cycle, then the system can maintain MU-MIMO spatial multiplexing, but terminals outside this limit experience communication delays
Solution Approach 1:
The patent applies periodic action by systematically rotating different groups of terminals to transmit reference symbols and participate in MU-MIMO communication across successive data transmission cycles. This ensures that while only M terminals are actively served in each cycle, all P terminals receive regular communication opportunities over time, reducing the perception of delay and ensuring fair resource distribution.
Solution Approach 2:
The patent implements dynamic terminal selection and group rotation based on varying channel conditions and traffic requirements. The system dynamically adjusts which terminals are included in the active group for reference symbol transmission and MU-MIMO communication, allowing terminals that have been waiting longer or have higher priority to be selected in subsequent cycles, thereby reducing overall communication delay.
Data Source
AI summary
A base station includes a memory holding information on P terminals in connecting to the base station, where P is an integer of 3 or more, a determination unit that determines L terminals to transmit a reference symbol used for measurement of channel state information indicating a state of a propagation path to the base station from among the P terminals based on the information on the P terminals, at every data transmission cycle, where L is an integer satisfying 2≤L<P, a selector that selects M terminals capable of spatial multiplexing communication in the data transmission cycle based on a measurement result of the channel state information based on reception of the reference symbol transmitted from L terminals, where M is an integer satisfying 2≤M≤L, and receives respective pieces of data transmitted from the M terminals via a plurality of antennas.