PUSCH Rank Indicator Encoding for 3-Bit LTE-Advanced Feedback
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Solution Overview
Problem
Existing 3GPP LTE and LTE-advanced systems lack methods for efficiently encoding and transmitting channel rank information (RI) when the number of bits exceeds three, particularly with increased transmitter antennas or carrier aggregation, which is necessary for improved data transmission rates and carrier aggregation.
Innovation Solution
A method involving mapping channel RI to a 3-bit or more bit string and applying Reed-Muller coding with a 32-bit code length, followed by modulation symbol generation, to efficiently transmit channel RI using a physical uplink shared channel (PUSCH).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of transmitter antennas is increased to eight or more for LTE-advanced, then the data transmission rate is improved, but the number of bits required to transmit channel RI increases to three or more, which is not supported by existing encoding methods
Solution Approach 1:
The patent changes the encoding parameters by introducing a mapping table that assigns 3-bit RI values to specific modulation symbols (QPSK, 16-QAM, or 64-QAM) based on the number of transmitter antennas. This allows the system to adapt the encoding scheme to match the increased antenna configuration, enabling proper transmission of 3-bit RI values that indicate channel ranks from 1 to 8.
2Productivity
If carrier aggregation is implemented to aggregate multiple carrier bands, then the data transmission capacity is improved, but the number of bits for transmitting channel RI increases, which exceeds the existing two-bit limitation
Solution Approach 1:
The patent modifies the RI encoding parameters by using a mapping table that translates 3-bit RI values into appropriate modulation symbols. This ensures that when carrier aggregation involves multiple carrier bands requiring 3-bit RI values, the system can accurately represent all possible channel rank combinations (1-8) without information loss.
Solution Approach 2:
The patent creates a universal encoding solution that works for both traditional two-antenna configurations (1-bit RI) and advanced eight-antenna configurations (3-bit RI) by using a single mapping table that accommodates different RI bit widths. This multi-functional approach allows the same PUSCH transmission mechanism to handle various carrier aggregation scenarios without requiring separate encoding schemes.
3Measurement precision
If three bits are used to transmit channel RI for eight transmitter antennas, then the channel feedback precision is improved, but the existing repetition coding method in 3GPP LTE release 8/9 does not support this bit width
Solution Approach 1:
The patent changes the encoding parameter by introducing a mapping table that specifically maps 3-bit RI values to modulation symbols suitable for PUSCH transmission. This table-based approach provides a straightforward implementation method that maintains compatibility with existing LTE release 8/9 repetition coding while extending support to 3-bit RI values for eight-antenna configurations.
Data Source
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AI summary
Provided is a method of transmitting channel rank information (RI) when the number of bits for transmitting the channel RI to be transmitted through a physical uplink shared channel (PUSCH) is three or more. The method includes mapping channel RI to be transmitted to a channel RI bit string of 3 bits or more, Reed-Muller coding and rate-matching the channel RI bit string using a basis sequence having a 32-bit code length, and generating modulation symbols by applying the bit sequence that has been Reed-Muller coded and rate-matched to a modulation mapper. Accordingly, the method of transmitting downlink channel RI can be employed when five or more antennas are used for downlink transmission or several carrier bands are used by carrier aggregation as specified in Third Generation Partnership Project (3GPP) long term evolution (LTE)-advanced following 3GPP LTE release 10.