PHICH Resource Allocation for LTE TDD Cross-Carrier Scheduling
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Solution Overview
Problem
In LTE TDD systems with carrier aggregation, cross-carrier scheduling between serving cells with different subframe ratios poses challenges in effectively reserving and allocating PHICH resources, particularly when introducing new subframe ratios or flexible subframes, leading to inefficiencies in data transmission.
Innovation Solution
The method involves a network-side device sending and receiving different subframe ratio information to user equipment, determining acknowledgement subframes based on specific timing relations, and reserving corresponding PHICH resources to ensure efficient acknowledgement transmission, either using existing or reserved PHICH resource sets depending on their availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cross-carrier scheduling is performed between serving cells with different subframe ratios, then the system supports more flexible subframe configurations and new functions, but the PHICH resource allocation becomes complex and inefficient
Solution Approach 1:
The PHICH resource allocation is segmented by creating separate PHICH resource sets for different subframe ratios. Each PHICH resource set is independently configured and managed, allowing the system to handle multiple subframe ratios without interference. This segmentation resolves the complexity by dividing the resource allocation into manageable, ratio-specific segments.
Solution Approach 2:
The network side device performs preliminary configuration of PHICH resource sets before actual data transmission. By pre-defining the timing relations and resource allocations for different subframe ratios, the system avoids complex real-time calculations and resolves the allocation complexity in advance.
2Reliability
If PHICH resources are reserved for each cross-carrier scheduled serving cell, then acknowledgement feedback is reliable, but PHICH resource overhead increases
Solution Approach 1:
A single PHICH resource set can serve multiple serving cells by utilizing the association relationship between PHICH resources and serving cell indices. This multi-functionality allows the same PHICH resources to provide acknowledgement feedback for different cells, reducing overall resource overhead while maintaining reliability.
Solution Approach 2:
The system changes the parameter of PHICH resource configuration by introducing PHICH resource sets with different timing relations for different subframe ratios. This parameter change allows efficient resource utilization by matching PHICH resources to the specific timing requirements of each serving cell, reducing waste while ensuring reliable feedback.
3Productivity
If multiple PHICH resource sets are configured for different subframe ratios, then acknowledgement transmission is optimized for each ratio, but system configuration complexity increases
Solution Approach 1:
The system dynamically selects which PHICH resource set to use based on the subframe ratio of the current transmission. This dynamic selection, guided by timing relation parameters, allows the system to optimize acknowledgement transmission for each specific ratio while managing configuration complexity through automated selection logic.
Solution Approach 2:
The network side device provides feedback to the user equipment about the configured PHICH resource sets and their associated timing relations. This feedback mechanism ensures that both sides have consistent understanding of the configuration, reducing complexity by establishing clear communication protocols for resource set identification and selection.
Data Source
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AI summary
Embodiments of the present invention provide a method and a device for sending and receiving an acknowledgement. The sending method includes: sending first subframe ratio information and second subframe ratio information to a UE; reserving a first PHICH resource set in a first acknowledgement subframe set; reserving a second PHICH resource set in an acknowledgement subframe, in which the first PHICH resource set does not exist, of a second acknowledgement subframe set; receiving uplink data sent by the UE; determining an acknowledgement subframe for the uplink data; and sending an acknowledgement to the UE by using a PHICH resource in the first PHICH resource set if the first PHICH resource set exists in the acknowledgement subframe, or sending an acknowledgement to the UE by using a PHICH resource in the second PHICH resource set if the first PHICH resource set does not exist in the acknowledgement subframe. PHICH resource overhead of a system is lowered and data transmission for the user equipment is ensured.