TTI Bundling for Msg3 in LTE Random Access
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Solution Overview
Problem
In wireless communication systems, particularly at the edge of communication cells, transmission quality is reduced due to high interference and low transmission power, leading to delays in decoding data, especially for Msg3 transmissions which are not TTI bundled, resulting in increased random access latency and impaired performance of TTI bundled transmissions.
Innovation Solution
Implementing TTI bundling for Msg3 transmissions by allocating a TTI-bundled transmission opportunity, allowing non-adaptive transmission of Msg3 in consecutive subframes without HARQ feedback, and modifying communication protocols to support coexistence of TTI bundling and semi-persistent scheduling, ensuring efficient decoding and reducing delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If TTI bundling is implemented for Msg3 transmissions, then decoding time is reduced and transmission efficiency is improved, but protocol complexity increases due to the need to modify communication standards to support coexistence with semi-persistent scheduling
Solution Approach 1:
The patent segments the transmission opportunities into TTI-bundled transmissions and semi-persistent scheduling transmissions, allowing each to operate with specific characteristics. By dividing the transmission process into distinct segments with different bundling configurations, the system reduces decoding time for TTI-bundled transmissions while managing protocol complexity through structured separation of functions.
Solution Approach 2:
The patent introduces dynamic configuration capabilities where the network can adaptively select between TTI-bundled transmission and semi-persistent scheduling based on current channel conditions and traffic requirements. This dynamic adaptation allows the system to optimize decoding time when needed while maintaining protocol flexibility, resolving the contradiction between performance improvement and complexity management.
2Reliability
If Msg3 transmissions are made non-adaptive with TTI bundling, then transmission reliability is improved for cell-edge users, but adaptability to varying channel conditions is reduced
Solution Approach 1:
The patent employs parameter changes by allowing the network to modify transmission parameters such as TTI bundling configuration, modulation and coding scheme, and resource allocation based on channel conditions. This enables the system to maintain high reliability for cell-edge users through TTI bundling while preserving adaptability by dynamically adjusting parameters according to varying radio environment conditions.
Solution Approach 2:
The patent implements preliminary configuration of TTI-bundled transmission opportunities where the network pre-establishes bundled transmission patterns before actual data transmission. This preliminary setup ensures reliability by preparing optimized transmission parameters in advance, while the system maintains adaptability by allowing reconfiguration based on observed channel conditions during operation.
3Productivity
If TTI bundling is applied to all transmissions, then decoding efficiency is improved, but system flexibility is reduced due to inability to support both TTI bundling and semi-persistent scheduling simultaneously
Solution Approach 1:
The patent segments the transmission system into distinct TTI-bundled transmission channels and semi-persistent scheduling channels, allowing each segment to operate with optimized parameters for its specific function. This segmentation enables high decoding efficiency for TTI-bundled transmissions while preserving system flexibility by maintaining separate pathways for different transmission modes.
Solution Approach 2:
The patent achieves multi-functionality by designing a unified transmission framework that can accommodate both TTI-bundled transmissions and semi-persistent scheduling transmissions. The system uses universal resource allocation mechanisms and control structures that support multiple transmission types simultaneously, thereby maintaining decoding efficiency for TTI bundling while preserving overall system flexibility and adaptability.
Data Source
AI summary
TTI bundling is included for Msg3 transmissions in LTE communications. A reserved group of preambles or reserved set of random access preamble transmission opportunities are used to indicate user equipment (UE) need of uplink (UL) transmission of a TTI-bundled Msg3. The UE transmits the same redundancy version for transmissions within a TTI bundle as the eNB expects even if any of the transmissions are dropped due to collisions with an Msg3 transmission. In addition, co-existence of TTI bundling and UL semi-persistent scheduling (SPS) for TDD DL/UL configurations is provided using SPS intervals which are multiples of various fixed time periods.