PHICH-less Uplink Scheduling for TDD Configuration Zero
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Solution Overview
Problem
In LTE systems, inter-band carrier aggregation with different uplink/downlink configurations on different bands faces challenges in handling PHICH-less cases, particularly in cross-carrier scheduling scenarios where the PHICH resource is not available, leading to issues with PUSCH scheduling and HARQ timing alignment between legacy and inter-band CA UEs.
Innovation Solution
The method involves using a two-bit new data indicator to trigger and schedule physical uplink shared channel transmissions on a secondary cell configured with time division duplex uplink/downlink configuration zero, allowing for adaptive retransmissions and new transmissions without relying on PHICH, and employing a single uplink grant to manage multiple HARQ processes, thereby addressing the PHICH-less scenario.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single uplink grant is used to trigger multiple PUSCH transmissions without PHICH, then device complexity is reduced and scheduling efficiency is improved, but HARQ timing alignment becomes difficult to manage
Solution Approach 1:
The patent segments the HARQ process by introducing separate HARQ process identifiers for different PUSCH transmissions triggered by a single uplink grant. This allows the system to manage multiple HARQ processes independently without requiring PHICH, resolving the timing alignment issue while maintaining scheduling efficiency.
Solution Approach 2:
The patent applies preliminary action by pre-configuring HARQ process parameters and timing relationships in the uplink grant before transmissions occur. This pre-configuration establishes clear timing alignment rules for multiple PUSCH transmissions without requiring real-time PHICH feedback.
2Adaptability or versatility
If PHICH is not used in inter-band TDD CA with different UL-DL configurations, then adaptability to diverse network scenarios is improved, but PUSCH scheduling reliability deteriorates
Solution Approach 1:
The patent implements feedback mechanisms through explicit HARQ process identifiers and timing relationship signaling in the uplink grant. This provides the necessary feedback for reliable PUSCH scheduling without relying on PHICH, maintaining adaptability across different TDD configurations.
Solution Approach 2:
The patent introduces an intermediary mechanism where the uplink grant itself carries HARQ process information and timing parameters, acting as a mediator between the scheduler and the PUSCH transmissions. This replaces the PHICH intermediary function while supporting diverse UL-DL configurations.
3Productivity
If multiple HARQ processes are managed by a single uplink grant, then productivity is improved through efficient resource utilization, but difficulty of detecting and measuring increases
Solution Approach 1:
The patent uses distinct HARQ process identifiers as unique identifiers for different HARQ processes, similar to color-coding different items. This makes it easy to distinguish and track multiple HARQ processes managed by a single uplink grant, reducing the difficulty of detection and measurement while improving productivity.
Data Source
AI summary
Various communication systems may benefit from techniques for handling inter-band carrier aggregation (CA). For example, systems of the third generation partnership project (3GPP) long term evolution (LTE) advanced (LTE-A) may benefit from a uplink (UL) downlink (DL) configuration zero handling, particularly in cases where there is no physical hybrid automatic repeat request (HARQ) indicator channel (PHICH). For example, certain embodiments may be applicable to inter-band CA having different UL/DL configuration in use. A method can include triggering in a downlink subframe a first physical uplink shared channel transmission in a first hybrid automatic repeat request process. The method can also include triggering in the downlink subframe a second physical uplink shared channel transmission in a second hybrid automatic repeat request process. The secondary cell can be configured with time division duplex uplink/downlink configuration number zero. The triggerings can be performed by means of a single uplink grant but without a hybrid automatic repeat request indicator.