Multi-User MIMO Precoding with Clipping Thresholds

Solution Overview

Problem

Conventional wireless communication apparatuses face limitations in channel capacity due to limited antennas and radio units, leading to increased device scale and power consumption, especially when using multi-user MIMO transmission methods like Tomlinson-Harashima precoding or vector perturbation, which require wider dynamic ranges and higher power consumption.

Innovation Solution

A wireless communication apparatus that sets upper limit values for additional signals in multi-user MIMO transmission, allowing for precoding within defined ranges to minimize transmission power without exceeding device scale or power consumption, thereby maintaining effective channel capacity and system throughput.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If Tomlinson-Harashima precoding or vector perturbation is applied in multi-user MIMO transmission, then channel capacity and system throughput are improved, but device scale and power consumption increase due to wider dynamic range requirements

Engineering Contradiction:

Improvechannel capacityVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent changes the parameter of dynamic range by introducing clipping threshold values that limit the amplitude of precoded signals. This parameter change allows the system to maintain the benefits of precoding for channel capacity while restricting the signal dynamics to fit within the receiver's fixed dynamic range, thereby avoiding increased device scale and power consumption.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies preliminary anti-action by pre-clipping or pre-normalizing the precoded signals before transmission to prevent the receiver from needing to handle excessive dynamic ranges. The base station processes signals to ensure they fall within acceptable amplitude bounds, thereby protecting the receiver from requiring larger dynamic ranges and associated increased power consumption.

Inventive Principle:

Principle #9Preliminary anti-action

2Productivity

If Tomlinson-Harashima precoding or vector perturbation is applied in multi-user MIMO transmission, then channel capacity and system throughput are improved, but device scale increases due to wider dynamic range requirements

Engineering Contradiction:

Improvechannel capacityVSAvoiddevice scale

Core Design Contradiction:

ProductivityVSVolume of moving object

Solution Approach 1:

The patent changes the parameter of dynamic range by introducing clipping threshold values that limit the amplitude of precoded signals. This parameter change allows the system to maintain the benefits of precoding for channel capacity while restricting the signal dynamics to fit within the receiver's fixed dynamic range, thereby avoiding increased device scale.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If beamforming only is used for multi-user MIMO multiplexing, then device complexity is reduced and implementation is easier, but performance degrades significantly when propagation path correlation is high between terminals

Engineering Contradiction:

Improveimplementation complexityVSAvoidcommunication performance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent segments the precoding function into two parts: the base station performs linear precoding with controlled output amplitude, and the receiver performs simple detection without needing complex iterative processing. This segmentation allows the system to achieve reliability benefits of precoding while keeping device complexity low at the receiver side.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8175633B2Wireless communication apparatus, system, method, and program

Publication Date: 2012.05.08 INT SEMICON GRP

AI summary

A wireless communication apparatus includes a first storage unit configured to store each of a plurality of upper limit values of absolute values of additional signals that are set for a corresponding one of a plurality of first wireless communication apparatuses and are added when a plurality of modulation symbols to be transmitted to the first wireless communication apparatuses are precoded, a coding unit configured to decide each of a plurality of first values of the additional signals for a corresponding one of the first wireless communication apparatuses within ranges defined by the upper limit values, and precode the modulation symbols using the first values to obtain a plurality of transmission signals, and a first transmission unit configured to transmit, using multi-user MIMO (Multiple Input Multiple Output), the transmission signals to the first wireless communication apparatuses.