TTI Bundling in TDD Configurations with Fewer Than Four Subframes
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Solution Overview
Problem
Conventional TTI bundling in LTE systems with TDD configurations is limited by the requirement for consecutive subframes, which is not supported in configurations with fewer than four consecutive subframes, leading to increased latency and inefficiencies in data transmission.
Innovation Solution
The method allows for variable bundle sizes and non-consecutive subframe transmissions, enabling TTI bundling in TDD configurations by comparing the bundle size with the available number of subframes and selecting an appropriate set of subframes for data transmission, thereby accommodating configurations with fewer than four consecutive subframes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional TTI bundling uses four consecutive subframes for data transmission, then data reception robustness is improved, but the system cannot support TDD configurations with fewer than four consecutive uplink subframes
Solution Approach 1:
The patent makes the TTI bundling parameters dynamic by allowing the bundle size to be configurable rather than fixed at four transmissions. The system can adapt the number of consecutive subframes used for bundling based on the specific TDD configuration, enabling support for configurations with fewer than four consecutive uplink subframes while maintaining the core benefit of multiple transmissions for improved reception robustness
Solution Approach 2:
The invention changes the parameters of TTI bundling from fixed values to configurable variables. Specifically, the bundle size (number of transmissions) and the TDD configuration (number of consecutive uplink subframes) are made adjustable parameters that can be optimized for different deployment scenarios and configuration requirements, thereby resolving the contradiction between maintaining robust reception and supporting diverse TDD configurations
2Reliability
If data is re-transmitted multiple times until successful reception, then data transmission reliability is improved, but transmission latency increases
Solution Approach 1:
The patent implements preliminary action by performing multiple transmissions of the same data block within a single TTI bundling interval before waiting for HARQ feedback. This allows the system to proactively send redundant copies of the data in advance, so that if the first transmission fails, the receiver already has backup copies to use, thereby reducing the need for additional round-trip delays for retransmission while maintaining high reliability
Data Source
AI summary
A base station and a user equipment (UE) device may communicate over an air interface in a particular time division duplexing (TDD) configuration. The TDD configuration specifies a certain number of consecutive subframes for uplink communications and a certain number of consecutive subframes for downlink communications. A transmitter (either the UE device or the base station) may transmit data using transmission time interval (TTI) bundling with a bundle size of N. To select a set of N subframes to use to transmit the data, the transmitter may compare N to C, the number of consecutive subframes available to transmit the data. If N≤C, the N subframes in the set are consecutive subframes. If N>C, the set of N subframes includes C consecutive subframes and at least one additional subframe that is separated from the consecutive subframes by one or more subframes not in the set.