TTI Bundling for V2X in Unlicensed Spectrum
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Solution Overview
Problem
In wireless communication systems, vehicles often face issues with discontinuous or delayed data transmissions due to data payloads exceeding the allocated resources within a single Transmission Time Interval (TTI), leading to increased latency and decreased throughput, especially when using contention-based mechanisms like listen-before-talk (LBT) in shared radio frequency spectrum bands.
Innovation Solution
User Equipment (UE) implements TTI bundling by determining the data size and type, and if it exceeds a threshold, configures subsequent TTIs for data transmission, using control and LBT symbols to manage resource allocation and transmission across multiple TTIs, thereby optimizing resource usage and reducing contention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a vehicle uses contention-based mechanisms like listen-before-talk (LBT) in shared radio frequency spectrum bands, then the vehicle can access the channel, but data payloads exceeding the allocated TTI resources cause discontinuous or delayed transmissions, increasing latency and decreasing throughput
Solution Approach 1:
The patent combines multiple TTIs into a bundled structure where multiple data transmissions are aggregated within a single TTI allocation. This merging allows the vehicle to transmit larger data payloads without requiring multiple separate contention cycles, thereby reducing latency and improving throughput by eliminating discontinuous transmissions.
Solution Approach 2:
The patent applies preliminary action by performing LBT and resource allocation in advance before the actual data transmission begins. The vehicle determines the size of data to be transmitted and configures subsequent TTIs for data transmission before the transmission starts, ensuring continuous transmission without interruptions and reducing latency.
2Ease of operation
If a vehicle transmits data in a single TTI, then the transmission is simple and fast, but data payloads exceeding the allocated resources require re-contention, causing discontinuous transmissions
Solution Approach 1:
The patent segments the data transmission process into multiple TTIs that are bundled together. Instead of attempting to transmit the entire data payload in a single TTI, the data is divided across multiple TTIs within the bundled structure, allowing the vehicle to maintain continuous transmission while managing larger payloads that would otherwise require re-contention.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining the data transmission process across multiple TTIs without interruption. The bundled TTI structure allows the vehicle to continue transmitting data seamlessly from one TTI to the next, eliminating the discontinuities that would occur with separate contention-based transmissions and improving overall transmission reliability.
3Quantity of substance
If the vehicle performs multiple contentions to transmit large data payloads, then the data can be transmitted in smaller segments, but the overall transmission time increases and throughput decreases
Solution Approach 1:
The patent merges multiple data transmission segments into a single bundled TTI structure. Instead of performing multiple separate contentions for different data segments, the vehicle aggregates all segments into one TTI allocation, transmitting them continuously. This merging approach maintains the ability to handle large data payloads while significantly improving throughput by eliminating the time lost in multiple contention cycles.
Data Source
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AI summary
Methods, systems, and devices are described for vehicle-to-everything (V2X) communication over one or more determined transmission time intervals (TTIs) in an unlicensed (shared) radio frequency spectrum band. A user equipment (UE) such as a vehicle may perform one or more listen-before-talk (LBT) mechanisms on the shared radio frequency spectrum and contend for access to available system resources. Upon gaining access, the UE may determine a data payload for transmission. The data type or payload may exceed a threshold and as a result, the UE may bundle a multiple TTIs for continuous data transmission. The UE may send control information, indicating a TTI bundling implementation as well as modification to the control or LBT symbols of subsequent TTIs of the data transmission, and subsequently perform data transmission over a plurality of TTIs.