ACK Resource Mapping in Single Carrier FDMA Systems
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Solution Overview
Problem
Current communication systems face inefficiencies in transmitting acknowledgement channel messages due to high overhead in explicit signaling and resource requirements, especially in LTE systems, where the number of bits needed to identify user equipment (UE) is large, leading to suboptimal ACK/NACK bit error rates and increased signaling overhead.
Innovation Solution
Establishing a functional relationship between uplink acknowledgement channel resources and downlink control channel resources through mapping schemes, such as using Zadoff-Chu sequences and phase-shift-keying, to reduce the need for explicit signaling and optimize resource allocation, allowing for efficient transmission of multiple ACKs/NAKs without increasing overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If explicit signaling is used to transmit ACK channel resource information, then the resource allocation can be clearly indicated, but the signaling overhead becomes large
Solution Approach 1:
The patent extracts the resource allocation information from explicit signaling and embeds it in the data channel resources themselves. By removing the redundant control signaling and using the data channel's resource structure to carry ACK information, the system eliminates the need for separate explicit ACK resource indication while maintaining clear resource allocation knowledge at the receiver.
Solution Approach 2:
The data channel resources are made multi-functional, serving both data transmission and ACK channel resource indication purposes. The same resource elements that carry data also encode information about ACK resource allocation, allowing a single signaling mechanism to fulfill multiple functions and thereby reducing overall signaling overhead.
2Loss of information
If ACK channel resources are linked to data channel resources, then resource allocation can be indicated, but the required ACK channel resources increase significantly
Solution Approach 1:
Instead of allocating full dedicated ACK channel resources for every possible data channel configuration, the patent uses a partial mapping approach where a subset of data channel resources is used to indicate ACK resource allocation. This partial action approach reduces the total ACK channel resource requirement while still providing sufficient information for proper resource allocation.
Solution Approach 2:
The patent changes the parameter used for resource indication from dedicated ACK channel resource indices to data channel resource indices. By transforming the indication mechanism to use data channel resource parameters, the system reduces the quantity of ACK channel resources needed while maintaining the ability to clearly indicate resource allocation.
3Loss of information
If UE ID is attached to ACK/NACK bits, then the destination can be clearly identified, but the number of bits per UE becomes significantly larger
Solution Approach 1:
The patent removes the UE ID from the ACK/NACK signaling and extracts the destination identification function from the bit stream. By taking out the redundant UE ID and relying on the structured resource allocation mapping, the system maintains clear destination identification with significantly fewer bits.
Solution Approach 2:
The resource allocation mapping acts as an intermediary that translates between the physical resource indices and the logical destination identification. Instead of directly embedding UE IDs in the bit stream, the system uses the resource mapping relationship as an intermediary to convey destination information, reducing the bit requirement while maintaining identification capability.
4Measurement precision
If more bits are used per UE in ACK/NACK signaling, then destination indication is more accurate, but the overhead increases and bit error rate increases
Solution Approach 1:
The patent extracts the destination indication function from high-bit-rate UE-specific signaling and relocates it to the resource allocation mapping structure. By removing the need for lengthy UE ID fields and using the structured mapping of resources to destinations, the system achieves accurate destination indication with minimal overhead and reduced bit error rate.
Data Source
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AI summary
A mapping scheme between a plurality of control channel element sets and a plurality of acknowledgement channel resource sets is established. Each of the control channel element sets includes at least one control channel element, and each of the acknowledgement channel resource sets includes at least one acknowledgement channel resource. In accordance with a scheduling grant transmitted using a control channel element set selected from the plurality of control channel element sets, a data packet is transmitted via a second node to a first node. Then, an acknowledgement channel message is transmitted via the first node to the second node by using at least one acknowledgement channel resource selected from the acknowledgement channel resource set that correspond to the control channel element set used for transmitting the scheduling grant in accordance with the mapping scheme.