Uplink ACK Detection Using Differential Modulation and Codeword Correlation
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Solution Overview
Problem
In Broadband Wireless Access communication systems, the existing OFDM/OFDMA scheme faces challenges in reliably transmitting uplink ACK information due to insufficient pilot tones, leading to increased error probability and decreased channel estimation performance, which affects the stability and throughput of the communication system.
Innovation Solution
The method involves identifying first codewords used in data transmission, setting third codewords by adding second codewords, calculating correlation values of orthogonal vectors, and detecting information based on these values to enhance the detection of ACK information, thereby improving data rate and resource use efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a small quantity of frequency-time resources is allocated for transmitting uplink ACK information, then the overhead ratio is reduced, but the probability of error increases and channel estimation performance decreases
Solution Approach 1:
The patent changes the modulation parameter from coherent modulation to differential modulation for uplink ACK information transmission. This allows the system to achieve reliable transmission with minimal frequency-time resources by utilizing differential encoding characteristics, thereby resolving the contradiction between low overhead and high reliability.
Solution Approach 2:
The patent employs differential modulation which creates a relationship between consecutive symbols. The receiver uses the difference between current and previous symbols to decode information, effectively copying the encoding strategy to maintain reliability without requiring additional resources.
2Loss of energy
If a small quantity of frequency-time resources is allocated for transmitting uplink ACK information, then the overhead ratio is reduced, but channel estimation performance decreases
Solution Approach 1:
The patent uses differential modulation where the channel estimation is performed on differential symbols rather than requiring separate pilot tones. The receiver estimates channel characteristics by analyzing the differential encoding patterns, thereby achieving adequate channel estimation performance with minimal resources allocated for ACK transmission.
3Measurement precision
If the number of pilot tones is increased to improve channel estimation performance, then channel estimation performance improves, but the number of data tones becomes insufficient
Solution Approach 1:
The patent eliminates the need for separate pilot tones by using differential modulation for ACK information. The channel estimation is derived from the differential encoding structure itself, allowing all allocated resources to be used for data transmission and thereby maximizing data rate without sacrificing channel estimation performance.
4Reliability
If a large quantity of frequency-time resources is used for transmitting uplink ACK information, then stability is improved, but the overhead ratio increases and throughput decreases
Solution Approach 1:
The patent changes the transmission parameter from coherent modulation to differential modulation, which provides stability through differential encoding rather than through increased resource allocation. This allows the system to maintain high throughput by using minimal frequency-time resources while achieving stable and reliable ACK information transmission.
Data Source
AI summary
An apparatus and method for receiving data in a communication system are provided. The method includes identifying first codewords, which have been used in transmission of data by a transmitter, in the data received from the transmitter, setting third codewords by adding second codewords to the identified first codewords, calculating correlation values of orthogonal vectors corresponding to the third codewords and detecting information included in the data based on the calculated correlation values. Accordingly, feedback information may be better received and detected.