Dynamic TTI Bundle Size Selection for Wireless Reliability
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Solution Overview
Problem
Conventional TTI bundling in wireless communication systems can increase uplink channel utilization and battery depletion, while also introducing latency, as it transmits data multiple times before receiving a HARQ response, which may not be optimal due to varying channel conditions and device capabilities.
Innovation Solution
A method where a radio access network (RAN) determines the suitability of TTI bundling for a wireless communication device (WCD) based on power headroom reports, uplink shared channel utilization, re-transmission rates, and remaining battery life, selecting from multiple TTI bundle sizes (e.g., N=2, N=3, N=4) to adapt bundling to specific conditions, thereby optimizing data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TTI bundling is used to transmit data multiple times before receiving HARQ response, then data reception robustness is improved, but transmission latency increases
Solution Approach 1:
The patent implements dynamic TTI bundle size selection, where the RAN configures different bundle sizes (e.g., 2, 3, or 4 TTIs) based on current channel conditions, device capabilities, and traffic requirements. This dynamic adjustment allows the system to optimize between reliability and latency in real-time, rather than using a fixed bundle size of 4 TTIs.
Solution Approach 2:
The patent changes the parameter of TTI bundle size from a fixed value to a configurable variable. The RAN can select from multiple bundle size values (N=2, N=3, N=4) based on power headroom reports, channel quality indicators, and other feedback mechanisms, thereby adjusting the transmission parameters to resolve the contradiction between reliability and latency.
2Reliability
If TTI bundling transmits data four times in four consecutive TTIs, then data reception robustness is improved, but uplink channel utilization increases
Solution Approach 1:
The patent implements dynamic TTI bundle size selection, where the RAN configures different bundle sizes based on current uplink channel utilization metrics. When utilization is high, smaller bundle sizes are selected to conserve resources; when utilization is low, larger bundle sizes can be used to improve reliability without excessive resource consumption.
Solution Approach 2:
The patent changes the TTI bundle size parameter from a fixed value of 4 to a configurable variable that can be set to 2, 3, or 4. This allows the system to adjust the parameter based on uplink shared channel utilization, balancing reliability improvements against resource consumption.
3Reliability
If TTI bundling transmits data multiple times, then data reception robustness is improved, but battery depletion increases
Solution Approach 1:
The patent implements dynamic TTI bundle size selection that considers device battery status and power headroom reports. When power is limited, the system selects smaller bundle sizes or disables bundling entirely, thereby reducing energy consumption while maintaining adequate reliability through alternative mechanisms such as adaptive modulation and coding.
Solution Approach 2:
The patent changes the TTI bundle size parameter based on power headroom reports and battery status feedback from the device. This allows the system to adjust the transmission parameter to match available power resources, resolving the contradiction between reliability and energy consumption.
4Device complexity
If conventional TTI bundling uses fixed bundle size of 4, then implementation simplicity is maintained, but adaptability to varying channel conditions deteriorates
Solution Approach 1:
The patent implements dynamic TTI bundle size selection where the RAN configures different bundle sizes based on channel quality indicators, power headroom reports, and device feedback. This dynamic approach maintains relative implementation simplicity by using existing feedback mechanisms while significantly improving adaptability to varying channel conditions and device capabilities.
Solution Approach 2:
The patent changes the TTI bundle size from a fixed parameter to a configurable parameter that can be adjusted based on channel conditions. The RAN selects from predefined bundle size values (2, 3, or 4) based on feedback from devices, providing adaptability while maintaining implementation feasibility through standardized procedures.
Data Source
AI summary
A radio access network (RAN) determines whether transmission time interval (TTI) bundling is warranted for a wireless communication device (WCD) based on at least a power headroom report from the WCD. In response to determining that TTI bundling is warranted, the RAN selects a TTI bundle size, N, for the WCD and instructs the WCD to use the selected TTI bundle size. The TTI bundle size, N, could be selected from among a set of predefined values, such as N=2, N=3, and N=4. The selection could be based on various factors, such as a utilization of an uplink shared channel, a re-transmission rate of the WCD, and/or a remaining battery life of the WCD.