SC-FDMA Control Signaling Placement for Reliability
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Solution Overview
Problem
In SC-FDMA communication systems, there is a need to ensure better reception reliability for control bits, particularly ACK/NAK bits, which are transmitted alongside data bits, and to determine optimal placement and resource allocation for control and channel quality indicator (CQI) bits to maintain reliable communication under varying channel conditions.
Innovation Solution
The solution involves placing a reference signal on the first symbol of a slot, followed by HARQ-ACK on the second symbol, with data and CQI information placed on other symbols, ensuring that control bits are positioned close to the reference signal for improved channel estimation and reliability, and allocating resources based on channel conditions to prioritize ACK/NAK bit transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If control bits are transmitted alongside data bits in the same sub-frame, then resource utilization is improved, but reception reliability of control bits deteriorates
Solution Approach 1:
The patent segments the transmission resources by separating control bits and data bits into different time slots (symbols) within a sub-frame. Control bits are transmitted in specific symbols while data bits are transmitted in other symbols, allowing both to coexist without severe interference while maintaining their respective reliability requirements
Solution Approach 2:
The patent applies local quality by assigning different transmission parameters to control bits and data bits based on their respective reliability requirements. Control bits are given priority in resource allocation and can use more robust modulation and coding schemes in their designated symbols, while data bits use parameters optimized for their own requirements in other symbols
2Device complexity
If control bits are placed far from reference signals, then resource allocation is simplified, but channel estimation accuracy deteriorates
Solution Approach 1:
The patent performs preliminary action by placing reference signals at specific positions in the time domain before control bits are transmitted. This allows the receiver to perform channel estimation using these pre-positioned reference signals, improving the accuracy of channel estimation for subsequently received control bits in the same sub-frame
3Reliability
If more resources are allocated to control bits, then reception reliability is improved, but resource overhead increases
Solution Approach 1:
The patent applies partial action by allocating resources to control bits selectively rather than uniformly. Control bits are transmitted in specific symbols with dedicated resources when reliability is critical, while in other symbols or conditions, fewer resources may be allocated. This partial allocation approach maintains reliability where needed without unnecessarily increasing overall resource overhead
Data Source
AI summary
An apparatus and method are provided for transmitting control information and data in a DFT based communication system. The method includes placing a reference signal onto a first symbol among a plurality of symbols in one slot; placing a HARQ-ACK onto a second symbol first placed after the first symbol in the one slot; placing the data onto other symbols except for the first symbol; and transmitting a signal including the reference signal, the HARQ-ACK and the data. A part of CQI information is further placed onto at least one symbol, except for the first symbol, in case that the CQI information is present for transmission in the one slot.