TTI Bundling for Downlink Robustness in Wireless Systems

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Solution Overview

Problem

Wireless communication systems face challenges in providing robust downlink communication, particularly in scenarios with limited transmit power or degraded channel conditions, where existing technologies struggle to maintain effective communication.

Innovation Solution

The implementation of Transmission Time Interval (TTI) bundling in wireless communication systems, where a base station and wireless device enable TTI bundling to compensate for limited transmit power and degraded channel conditions by bundling downlink communications across component carriers, allowing for flexible enablement on a per-carrier basis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If transmit power is increased to improve downlink communication quality, then communication reliability is improved, but power consumption and interference increase

Engineering Contradiction:

Improvedownlink communication reliabilityVSAvoidtransmit power

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent combines multiple downlink transmissions into a single TTI bundle, transmitting the same data across multiple subframes with the same resource allocation. This merging approach allows the receiver to combine signals from multiple transmissions, achieving diversity gain and improved reliability without requiring proportional increases in transmit power for each individual transmission.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent performs preliminary actions by pre-configuring TTI bundling parameters and resource allocations before actual data transmission. The base station determines appropriate bundle sizes and resource configurations in advance based on channel conditions, allowing optimized power distribution across the bundled transmissions rather than reactive power adjustments.

Inventive Principle:

Principle #10Preliminary action

2Area of stationary object

If TTI bundling is enabled to compensate for limited transmit power, then communication coverage is improved, but system complexity increases

Engineering Contradiction:

Improvecommunication coverage areaVSAvoidsystem complexity

Core Design Contradiction:

Area of stationary objectVSDevice complexity

Solution Approach 1:

The patent segments the downlink communication into configurable TTI bundles with specific sizes (e.g., 2, 4, or 8 subframes). This segmentation allows flexible adaptation to different coverage requirements and channel conditions while maintaining manageable system complexity through standardized bundle configurations rather than requiring completely new communication protocols.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic TTI bundling configuration where the base station can adjust bundle sizes and enable/disable bundling on different component carriers based on real-time channel conditions and power availability. This dynamic adaptation allows the system to optimize coverage without permanently increasing complexity, as bundling parameters can be adjusted or deactivated when not needed.

Inventive Principle:

Principle #15Dynamics

3Reliability

If TTI bundling is applied on all component carriers to maximize robustness, then communication reliability is improved, but resource efficiency decreases

Engineering Contradiction:

Improvedownlink communication reliabilityVSAvoidresource efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies TTI bundling with different configurations on different component carriers based on their specific characteristics and channel conditions. Some carriers may use larger bundle sizes for better coverage, while others use smaller bundles or no bundling for higher efficiency. This localized optimization ensures that reliability improvements are achieved only where necessary, preserving resource efficiency on carriers with good channel conditions.

Inventive Principle:

Principle #3Local quality

4Reliability

If TTI bundle size is increased to improve robustness in degraded channel conditions, then communication reliability is improved, but transmission latency increases

Engineering Contradiction:

Improvedownlink communication reliabilityVSAvoidtransmission latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent enables dynamic adjustment of TTI bundle sizes based on channel conditions, allowing the system to use larger bundles only when channel degradation is detected. When channels are good, smaller bundles or no bundling is used to minimize latency. This dynamic approach balances reliability improvements against latency penalties, applying robustness only when and where channel conditions warrant it.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11832224B2TTI bundling for downlink communication

Publication Date: 2023.11.28 APPLE INC

AI summary

This disclosure relates to TTI bundling for downlink communication. According to one embodiment, a base station and a wireless device may establish a wireless communication link. The base station may determine to enable TTI bundling for downlink communication for at least one carrier of the wireless communication link. The base station may provide an indication to the wireless device to enable TTI bundling for downlink communication for the determined carrier(s) of the wireless communication link. The base station may subsequently transmit TTI bundle downlink communications to the wireless device via the determined carrier(s).