Single Channel Full Duplex Small Cell Interference Management

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Solution Overview

Problem

Massive MIMO multi-user beamforming (MM-MUBF) systems face significant overhead in channel estimation, especially when dealing with a large number of fast-moving User Equipment (UEs) and the need for in-band wireless backhaul, which requires frequent CSI estimation and efficient use of frequency resources.

Innovation Solution

Implementing Single Channel Full Duplex (SCFD) technology in base stations and small cells using massive MIMO with self-interference cancellation and interference suppression techniques, allowing simultaneous transmission and reception in the same frequency channel, and leveraging channel reciprocity to reduce estimation overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the number of RF chains and antennas is increased to provide high capacity wireless backhaul, then the throughput and spectral efficiency are improved, but the channel estimation overhead increases significantly

Engineering Contradiction:

ImprovethroughputVSAvoidchannel estimation overhead

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent segments the channel estimation process by separating backhaul channel estimation from access channel estimation. The BS-SC backhaul channels are estimated separately from the SC-UE access channels, allowing independent optimization of each estimation process and reducing overall overhead.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent makes the SC serve dual functions: as a receiver for BS downlink signals and as a transmitter for UE downlink signals simultaneously. This multi-functionality allows the same hardware infrastructure to support both wireless backhaul and access services, improving resource utilization.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Device complexity

If out-band wireless backhaul is used to avoid channel estimation overhead, then the channel estimation complexity is reduced, but the frequency resources are consumed

Engineering Contradiction:

Improvechannel estimation complexityVSAvoidfrequency resources

Core Design Contradiction:

Device complexityVSQuantity of substance

Solution Approach 1:

The patent merges the backhaul communication and access communication into the same frequency band. The BS communicates with SCs and the SC communicates with UEs simultaneously in-band, eliminating the need for separate out-band resources while managing interference through advanced signal processing.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent converts the harmful self-interference at the SC into a beneficial signal for channel estimation. The strong transmitted signal from the SC, which would normally be interference, is actually used to estimate the SC-UE access channel, turning a problem into a solution.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Quantity of substance

If in-band wireless backhaul is implemented to save frequency resources, then the frequency resource utilization is improved, but the self-interference at the SC increases

Engineering Contradiction:

Improvefrequency resource utilizationVSAvoidself-interference

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by pre-canceling the self-interference signal before it reaches the receiver. The SC transmits a known reference signal and uses it to generate and subtract an estimate of its own transmitted signal from the received signal, preventing the interference from degrading the desired signal.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent introduces an intermediary processing stage at the SC that mediates between the transmitted signal and the received signal. The self-interference cancellation module acts as an intermediary that processes the strong transmitted signal and removes its harmful effects before the weak desired signal is processed.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Measurement precision

If frequent channel estimation is performed for fast moving UEs, then the channel state accuracy is improved, but the time available for data communication is reduced

Engineering Contradiction:

Improvechannel state accuracyVSAvoiddata communication time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent segments the estimation requirements by recognizing that backhaul channels (BS-SC) change slowly while access channels (SC-UE) change rapidly due to UE mobility. This allows different estimation frequencies and methods to be applied to each channel type, optimizing the balance between accuracy and overhead.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS20170331526A1Massive MIMO multi-user beamforming and single channel full duplex for wireless networks

Publication Date: 2017.11.16 RF DSP INC

AI summary

This invention presents a method and apparatuses for wireless networking comprising one or more BS with Nbs antennas; two or more SCs in the range of a BS where a SC has Nsc antennas, uses Nsc1≦Nsc antennas for communication with a BS and uses Nsc2≦Nsc antennas for communication with one or more UEs; at the same time a BS transmitting DL signals to K SCs using multi-user transmit BF in a frequency channel, a SC simultaneously transmitting DL signals to one or more UEs in its range using the same frequency channel; and, at the same time a BS receiving UL signals from K SCs using multi-user receive BF in a frequency channel, a SC simultaneously receiving UL signals from one or more UEs in its range using the same frequency channel. Furthermore, beamforming using antennas on the SCs is performed to reduce the inter-SC interferences.