Contention-Based Uplink Acknowledgement via Dedicated PDCCH Feedback
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Solution Overview
Problem
In contention-based transmission schemes, the base station struggles to accurately provide feedback on the reception status of data from user equipment, leading to inefficiencies and increased latency due to the lack of specific identification of successfully received transmissions, resulting in incorrect ACK/NACK feedback for multiple user equipment.
Innovation Solution
A method and arrangement where a common identifier is used to send dedicated acknowledgement feedback on the physical downlink control channel, including the identity of user equipment that successfully received data, allowing for precise acknowledgement of successful transmissions within contention-based grants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a common identifier is used for contention-based grants, then multiple user equipments can share the same grant resource, but the base station cannot accurately identify which user equipment successfully transmitted data, leading to incorrect ACK/NACK feedback
Solution Approach 1:
The patent segments the feedback mechanism by introducing separate feedback channels: PHICH for common ACK/NACK feedback and PDCCH for dedicated ACK feedback. This segmentation allows the system to provide both general acknowledgment and user-specific acknowledgment, resolving the contradiction between shared resource usage and accurate identification.
Solution Approach 2:
The patent introduces an intermediary mechanism where the base station uses PDCCH messages containing C-RNTI identifiers to mediate between the common grant resource and individual user equipment. This intermediary allows accurate identification of successful transmissions while maintaining the efficiency of contention-based sharing.
2Measurement precision
If dedicated scheduling grants are used for each user equipment, then the base station can accurately identify and provide feedback for each transmission, but signaling overhead and latency increase due to scheduling request and grant exchange
Solution Approach 1:
The patent merges the advantages of both contention-based and scheduled access by combining common PHICH feedback with dedicated PDCCH feedback. This merging allows the system to maintain low latency through contention-based sharing while achieving accurate feedback through the combined feedback mechanism, avoiding the need for separate scheduling request exchanges.
3Device complexity
If a single ACK/NACK bit is sent for a common grant, then signaling overhead is reduced, but the feedback becomes incorrect for individual user equipments when multiple transmissions occur on the same grant
Solution Approach 1:
The feedback mechanism is segmented into two parts: a common PHICH channel that provides general ACK/NACK feedback with low overhead, and a dedicated PDCCH channel that provides user-specific feedback for accurate identification. This segmentation resolves the contradiction by distributing the feedback function across two channels with different overhead and reliability characteristics.
Solution Approach 2:
The patent applies partial action by sending ACK feedback only when necessary through PDCCH. The common PHICH provides baseline feedback, and the dedicated PDCCH feedback is added selectively to correct or supplement the common feedback when individual user equipment identification is needed, avoiding excessive signaling overhead while ensuring reliability.
Data Source
AI summary
A method is provided in a base station for providing feedback to user equipments on reception status of data transmitted by the user equipments. The base station and the user equipments are within a wireless communication system adapted for contention based transmissions. A common identifier is used to identify contention based grants on a physical downlink control channel. Upon successful reception of data from at least one of the plurality of user equipments, dedicated acknowledgement feedback is provided by including an indication of the identity of the at least one user equipment from which data was successfully received in a message to said common identifier on the physical downlink control channel. Related arrangements in a base station, methods in a user equipment, and arrangements in a user equipment are disclosed.