Coordinated Cell Transmissions via Orthogonal Cover Codes

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Solution Overview

Problem

Wireless communication systems face challenges in minimizing inter-cell interference at cell edges, despite advancements in MIMO systems, which affect the performance of mobile devices.

Innovation Solution

The implementation of a processing system that coordinates transmissions between cells using multiple antenna systems, including MIMO, to enhance performance by sending more spatial beams and minimizing interference, achieved through channel estimation and puncturing techniques to avoid reference signal collisions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If MIMO systems with multiple transmit antennas are introduced to generate directional fixed beam patterns, then system capacity and coverage are improved, but inter-cell interference at cell edges increases

Engineering Contradiction:

Improvesystem capacityVSAvoidinter-cell interference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent segments the transmission resources by introducing orthogonal cover codes (OCC) that divide the reference signal resources across different cells. This segmentation allows multiple cells to transmit reference signals simultaneously without collision, thereby maintaining system capacity while reducing inter-cell interference at cell edges.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent extends the reference signal design into the time domain by using orthogonal cover codes across multiple slots. This dimensional extension provides additional orthogonality resources, enabling reference signal multiplexing across cells without frequency or time conflicts, thus reducing interference while preserving capacity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Productivity

If reference signals are transmitted on overlapping subcarriers in frequency and time, then resource utilization is improved, but signal collision and interference increase

Engineering Contradiction:

Improveresource utilizationVSAvoidreference signal collision

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces orthogonal cover codes as an intermediary layer between different cell reference signals. These codes provide an additional dimension of orthogonality that mediates between overlapping reference signals, allowing them to coexist on the same time-frequency resources without collision or interference.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If coordinated transmissions between cells are implemented, then performance at cell edges is improved, but system complexity increases

Engineering Contradiction:

Improveperformance at cell edgesVSAvoidtransmission coordination complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-configuring orthogonal cover codes for reference signals in different cells before transmission. This advance preparation establishes orthogonality relationships in advance, eliminating the need for complex real-time coordination during transmission, thus improving cell edge performance while keeping system complexity manageable.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP2327168B1Coordinated transmissions between cells of a base station in a wireless communications system

Publication Date: 2014.11.19 QUALCOMM INC

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AI summary

Systems and methods for providing coverage to a first cell (104i) through a first antenna system (106i) and coverage to a second cell (104 j) through a second antenna system (106g). Data is also processed for transmission to a mobile device (108i) in the first cell using the first and second antenna systems.