Uplink Reference Signal Orthogonalization in MIMO Terminals

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Solution Overview

Problem

In MIMO transmission, existing technologies face challenges in orthogonalizing uplink reference signals between multiple antennas, which affects transmission efficiency in LTE systems.

Innovation Solution

A mobile terminal apparatus is designed with a reference signal generator and cyclic shift section to cyclically shift uplink reference signals, ensuring orthogonality between antenna ports, and a transmitter to send these signals to a radio base station, using techniques like distributed FDMA and block spreading for further orthogonality between users.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If MIMO transmission using plural antennas is adopted to achieve higher transmission speed, then transmission speed is improved, but orthogonalization of reference signals between plural antennas becomes problematic

Engineering Contradiction:

Improvetransmission speedVSAvoidorthogonality of reference signals

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies parameter changes by introducing a start point shift parameter (v) that varies across different antenna ports. Instead of using identical reference signals for all antennas, the system modifies the starting position of the reference signal sequence for each antenna port, thereby achieving orthogonality while maintaining MIMO transmission capabilities and high transmission speed.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If the same ZC sequences are used for uplink reference signals from multiple mobile terminal apparatus, then signal generation is simplified, but orthogonalization between different terminal apparatus becomes difficult

Engineering Contradiction:

Improvesignal generation simplicityVSAvoidorthogonality between terminal apparatus

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies segmentation by dividing the reference signal orthogonality into two independent dimensions: (1) orthogonality between different mobile terminal apparatus is achieved through cyclic shift values, and (2) orthogonality between different antenna ports is achieved through start point shifts. This segmentation allows each dimension to be handled independently while maintaining overall system simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces another dimension of orthogonality by adding the start point shift parameter (v) that is specific to each antenna port. This dimensional extension allows the system to achieve orthogonality in both the terminal apparatus dimension and the antenna port dimension simultaneously, resolving the conflict between simplicity and orthogonality.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS9048912B2Mobile terminal apparatus, radio base station apparatus and communication control method

Publication Date: 2015.06.02 NTT DOCOMO INC

AI summary

Provided are a mobile terminal apparatus, a radio base station apparatus and a communication method, capable of orthogonalizing uplink reference signals between plural antennas in MIMO transmission. The mobile terminal apparatus has a reference signal generator (11) for generating DM-RSs using ZC sequences and a cyclic shift section (13) for cyclically shifting the DM-RSs by unit of plural antenna ports (19) to orthogonalize the DM-RSs for the antenna ports (19) between the antenna ports (19), and the cyclically shifted DM-RSs are transmitted via the respective antenna ports (19) to a radio base station apparatus eNB in an uplink.