Embedding ACK/NACK Bits in CQI Reference Signals
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Solution Overview
Problem
In wireless cellular communication networks, existing technologies face challenges in reliably transmitting ACK/NACK bits in a timely manner to support Hybrid Automatic Repeat Request (HARQ) operations, especially in scenarios where channel quality indicators (CQI) are transmitted, due to the need for high reliability and efficient resource allocation.
Innovation Solution
The solution involves embedding ACK/NACK bits within CQI reference signals using quadrature amplitude modulation (QAM) in orthogonal frequency division multiple access (OFDMA) and single carrier frequency division multiple access (SC-FDMA) systems, allowing ACK/NACK information to be transmitted in reference symbols while maintaining channel estimation through pre-defined reference signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ACK/NACK bits are transmitted using dedicated physical uplink control channel (PUCCH), then transmission reliability is improved, but resource allocation efficiency deteriorates due to separate channel overhead
Solution Approach 1:
The patent combines ACK/NACK control information with CQI reference signals by embedding the ACK/NACK bits within the CQI reference signal structure. This merging eliminates the need for separate PUCCH resources, thereby improving resource allocation efficiency while maintaining transmission reliability through the integrated channel.
Solution Approach 2:
The CQI reference signal is designed to serve dual purposes: traditional channel quality indication and ACK/NACK control information transmission. This multi-functionality allows the same signal structure to carry both CQI and ACK/NACK, improving resource efficiency without sacrificing the reliability needed for HARQ operations.
2Productivity
If ACK/NACK bits are embedded in CQI reference signals, then resource allocation efficiency is improved, but transmission reliability deteriorates due to shared channel usage
Solution Approach 1:
The patent applies different modulation schemes to different parts of the transmitted signal. CQI data uses one modulation scheme while embedded ACK/NACK bits use a different, more robust modulation scheme. This local quality differentiation ensures that the ACK/NACK portion maintains high reliability even when embedded in the shared CQI reference signal channel.
Solution Approach 2:
The system incorporates redundancy and error protection mechanisms in advance for the embedded ACK/NACK bits. By pre-applying protective coding and robust modulation before transmission, the system cushions against potential reliability deterioration that could result from sharing the channel with CQI information.
3Reliability
If separate channels are used for CQI and ACK/NACK transmission, then transmission reliability is improved, but device complexity increases due to multiple channel management requirements
Solution Approach 1:
The patent merges CQI and ACK/NACK transmission into a single integrated signal structure. By combining these previously separate channels, the system reduces device complexity related to managing multiple channels while maintaining reliability through the unified transmission approach.
4Productivity
If ACK/NACK transmission timing is delayed to match CQI transmission, then resource allocation efficiency is improved, but HARQ operation performance deteriorates due to increased latency
Solution Approach 1:
The patent embeds ACK/NACK bits within the CQI reference signal structure in advance, preparing the combined signal for simultaneous transmission. This preliminary action allows both CQI and ACK/NACK to be transmitted together without delay, improving resource efficiency while avoiding HARQ latency penalties.
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 ensures timely and reliable transmission of ACK/NACK bits, enhancing HARQ operations by integrating control information directly into CQI transmissions, thereby improving the overall reliability and efficiency of wireless communication networks.
Implementation Method 1
embedding ACK/NACK bits within CQI reference signals using quadrature amplitude modulation (QAM)
Data Source
AI summary
A transmission within a wireless cellular network may include a first and second type of information. A subframe includes a plurality of symbols, at least one symbol is designated as a data symbol and at least one symbol is designated as a reference signal symbol that contains a pre-defined reference signal. The first type of information is embedded in the data symbols. If the second type of data is expected, then the second type of information is embedded in at least one reference symbol by quadrature amplitude modulating the pre-defined reference signal. The subframe is then transmitted from one node in the network to a second node. If it is determined that the second node is not expecting the second type of information, then a discontinuous transmission (DTX) response is embedded in the reference symbol instead of the second type of information.