Terminal NACK-Only Feedback Cyclic Shift Modulation
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Solution Overview
Problem
In multicast/broadcast services (MBS) for 5G NR, the network struggles to recognize the number of bits in NACK-only feedback due to varying configuration methods among user equipment (UE), necessitating blind decoding.
Innovation Solution
A terminal (UE) employs a control unit that applies a single cyclic shift index or two-phase shift modulation to resources of the uplink control channel for NACK-only feedback, assuming a specific correspondence between bit strings and resources, thereby simplifying feedback recognition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different configuration methods are used for NACK-only feedback among UEs, then feedback can be transmitted, but the network cannot recognize the number of bits and blind decoding is required
Solution Approach 1:
The patent applies parameter changes by using cyclic shift values as indicators to convey the number of NACK bits. Instead of using different configuration methods that require blind decoding, the system changes the parameter (cyclic shift value) to encode feedback information, allowing the network to recognize bit length without complex processing.
Solution Approach 2:
The patent replaces the mechanical blind decoding process with a signal-based indication system. Rather than requiring the network to mechanically try multiple decoding options, the cyclic shift value directly indicates the feedback bit length, substituting a complex mechanical search process with a simpler signal interpretation.
2Adaptability or versatility
If blind decoding is performed to recognize feedback bit length, then network can handle varying configurations, but processing time and complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-defining the relationship between cyclic shift values and feedback bit lengths. The indication is prepared in advance through the cyclic shift parameter, so when feedback is received, the network already knows how to interpret it without needing to perform time-consuming blind decoding operations.
3Quantity of substance
If multiple cyclic shift indices are applied to multiplex multiple bits, then feedback capacity increases, but configuration complexity increases
Solution Approach 1:
The patent applies universality by making the cyclic shift mechanism serve multiple functions: it both modulates the feedback signal and simultaneously indicates the number of bits. This single mechanism handles both signal transmission and information encoding, eliminating the need for separate configuration structures and reducing overall complexity while maintaining multiplexing capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables efficient NACK-only feedback in MBS, avoiding blind decoding and improving network recognition of feedback, thus enhancing communication reliability.
Implementation Method 1
applies only an index of one cyclic shift to one of the resources
Implementation Method 2
applies two-phase shift modulation to one of the resources
Data Source
AI summary
A terminal transmits the feedback of the automatic retransmission request. When the bit string of the feedback is associated with the resource of the uplink control channel and only the negative response is fed back, the terminal applies only the index of one cyclic shift to one resource.