Uplink Signal Multiplexing for CoMP Channel Measurement

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Solution Overview

Problem

In coordinated multi-point (CoMP) transmission systems, the existing method for obtaining channel state information (CSI) results in significant signaling overheads, affecting spectrum efficiency due to the need for multiple NodeBs to transmit and feedback downlink reference signals.

Innovation Solution

The method involves transmitting uplink signals in a multiplexing mode on both the uplink and downlink bands, allowing NodeBs to receive uplink signals on the downlink band for channel measurement, thereby reducing the need for downlink reference signals and feedback.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple NodeBs transmit downlink reference signals for CoMP transmission, then downlink channel measurement can be performed, but signaling overheads increase significantly

Engineering Contradiction:

Improvedownlink channel measurementVSAvoidsignaling overheads

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The patent inverts the traditional reference signal transmission direction by having the UE transmit uplink reference signals on the downlink band instead of the NodeB transmitting downlink reference signals. This allows the NodeB to measure downlink channel characteristics by receiving the uplink reference signals, thereby eliminating the need for multiple NodeBs to transmit downlink reference signals and significantly reducing signaling overheads.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The UE transmits uplink reference signals on the downlink band to enable the NodeB to perform downlink channel measurement autonomously. The UE's uplink transmission serves the dual purpose of uplink communication and downlink channel characterization, eliminating the need for separate downlink reference signal transmissions from multiple NodeBs.

Inventive Principle:

Principle #25Self-service

2Loss of information

If UE feeds back downlink CSI to each NodeB through uplink band, then channel state information is obtained, but spectrum efficiency decreases

Engineering Contradiction:

Improvechannel state informationVSAvoidspectrum efficiency

Core Design Contradiction:

Loss of informationVSProductivity

Solution Approach 1:

The patent eliminates the need for UE to feed back downlink CSI to multiple NodeBs by inverting the measurement approach. Instead of the UE measuring downlink signals and feeding back CSI, the NodeBs directly measure downlink channel characteristics by receiving uplink reference signals from the UE on the downlink band, thereby obtaining CSI without requiring uplink feedback transmissions.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent extracts the downlink channel measurement function from the uplink feedback process. By having the NodeB receive uplink reference signals on the downlink band, the system separates the channel measurement function from the traditional downlink reference signal transmission and UE feedback mechanism, thereby eliminating the overhead associated with transmitting and processing downlink CSI feedback.

Inventive Principle:

Principle #2Taking out (Extraction)

3Measurement precision

If downlink reference signals are transmitted for channel measurement, then CSI can be obtained, but system resources are consumed

Engineering Contradiction:

Improvechannel state informationVSAvoidsystem resources

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The uplink reference signal transmission by the UE serves multiple functions: it performs uplink communication and simultaneously enables downlink channel measurement when transmitted on the downlink band. This multi-functionality eliminates the need for separate downlink reference signals, thereby reducing consumption of system resources such as time frequency resources and transmission power.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent inverts the traditional approach where NodeBs transmit downlink reference signals to enable channel measurement. Instead, the UE transmits uplink reference signals on the downlink band, allowing the NodeB to measure downlink channels using the uplink transmissions. This inversion eliminates the need for dedicated downlink reference signal transmissions and reduces overall system resource consumption.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS8982808B2Method for transmitting a signal and communications apparatus

Publication Date: 2015.03.17 HUAWEI TECH CO LTD

AI summary

A method for transmitting a signal and a communications apparatus are provided. The method includes: obtaining a signal transmission mode, where the signal transmission mode indicates that an uplink signal is transmitted in a multiplexing mode; and transmitting the uplink signal on an uplink band and a downlink band in the multiplexing mode according to the obtained signal transmission mode. The communications apparatus includes: a first obtaining unit, configured to obtain a signal transmission mode, where the signal transmission mode indicates that an uplink signals is transmitted in a multiplexing mode; and a transmitting unit, configured to transmit the uplink signal on an uplink band and a downlink band in the multiplexing mode according to the obtained signal transmission mode. The technical solutions of embodiments of the present invention can reduce signaling overheads of the system and improve spectrum efficiency of the system when obtaining channel state information (CSI).