Carrier Aggregation Reply Message Assignment Module
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Solution Overview
Problem
In wireless communication systems employing interband carrier aggregation, the timing conflict between different uplink-downlink configurations of component carriers can prevent the transmission of acknowledgement and non-acknowledgement messages, such as HARQ ACK/NAK, due to incompatible UL-DL configurations between primary and secondary serving cells.
Innovation Solution
The implementation of a reply message assignment module that includes a downlink monitor and an uplink scheduler, which uses a downlink association set index to map downlink subframes to appropriate uplink subframes for transmitting HARQ ACK/NAK messages, ensuring compatibility across different UL-DL configurations by scheduling responses on a common uplink subframe or distributing them across multiple subframes based on specific indices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If interband carrier aggregation with different UL-DL configurations is implemented, then transmission bandwidth and data rates are improved, but timing conflicts prevent reliable transmission of control messages
Solution Approach 1:
The patent segments the control message transmission by introducing a separate feedback carrier (anchor carrier) dedicated to carrying HARQ ACK/NACK messages, distinct from the data carriers. This segmentation allows control messages to be transmitted independently on a carrier with a fixed UL-DL configuration, resolving the timing conflicts that arise when trying to use carriers with different configurations for both data and control transmissions.
Solution Approach 2:
The patent introduces an intermediary anchor carrier that mediates between the primary cell and secondary cells with different UL-DL configurations. This anchor carrier serves as a common reference point for control message transmission, allowing the system to maintain reliable control channel communication while enabling carrier aggregation with diverse configurations across multiple carriers.
2Area of stationary object
If multiple component carriers with different UL-DL configurations are aggregated, then bandwidth utilization is improved, but timing alignment for feedback messages deteriorates
Solution Approach 1:
The patent implements universality by designating one carrier as an anchor carrier that serves multiple functions: it carries both data transmissions and all control feedback messages (HARQ ACK/NACK) for the entire carrier aggregation system. This multi-functional anchor carrier provides a universal timing reference that works across all aggregated carriers with different configurations, eliminating feedback timing alignment issues.
3Device complexity
If feedback is restricted to primary serving cell only, then control message management is simplified, but transmission flexibility across different configurations is reduced
Solution Approach 1:
The patent merges the control message transmission function across all secondary cells into the primary serving cell (anchor carrier). Instead of allowing each cell to independently manage its own control messages, the system combines all HARQ feedback transmissions onto the anchor carrier, maintaining simplified control management while enabling support for multiple carrier configurations through the anchor carrier's universal role.
Data Source
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AI summary
An apparatus may include a radio frequency (RF) transceiver to receive a first message over a first carrier in a first band in a downlink sub-frame of a first radio frame in a communications link, where the communications link comprises interband carriers aggregated over primary and secondary cells. The apparatus may also include a processor and a reply message assignment module operable on the processor to determine a downlink sub-frame in which the downlink transmission is received and to adjust timing of a reply/acknowledge message to be sent by the RF transceiver in response to the first message so as to coincide with a predetermined uplink sub-frame of a radio frame. Other embodiments are described and claimed.