Uplink Control Channel Transmission Diversity in LTE
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Solution Overview
Problem
LTE lacks a scheme to select multiple combinations of radio resources, cyclic shifts, and orthogonal code sequences in the time domain for transmission diversity on the uplink control channel, limiting its ability to utilize transmission diversity effectively while maintaining compatibility with LTE.
Innovation Solution
The system employs a method where mobile station apparatuses select and use multiple combinations of radio resources, cyclic shifts, and orthogonal code sequences in the time domain for each transmission antenna, allowing for code spread and transmission diversity without altering the existing channel structure, enabling compatibility with LTE and LTE-Advanced.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LTE uses a single carrier communication scheme with code spread for uplink control channel, then compatibility with LTE is maintained, but transmission diversity cannot be effectively utilized
Solution Approach 1:
The patent segments the uplink control channel transmission into multiple independent components: multiple radio resources (frequency bands), multiple cyclic shifts, and multiple orthogonal code sequences. Each transmission antenna uses a unique combination of these segmented elements, enabling transmission diversity while keeping each individual component simple and compatible with LTE standards.
Solution Approach 2:
The patent extends the single-dimension code spread approach into multiple dimensions by introducing combinations of radio resources (frequency domain), cyclic shifts (time domain phase rotation), and orthogonal code sequences (code domain). This multi-dimensional approach enables transmission diversity without increasing the complexity of any single dimension beyond LTE capabilities.
2Reliability
If multiple combinations of radio resources, cyclic shifts, and orthogonal code sequences are selected for transmission diversity, then transmission diversity gain is achieved, but scheduling and resource allocation complexity increases
Solution Approach 1:
The patent establishes predetermined rules and formulas for selecting combinations of radio resources, cyclic shifts, and orthogonal code sequences for each transmission antenna. These selection rules are defined in advance in the standard specification, allowing both base station and mobile station to independently determine the appropriate combinations without complex real-time scheduling negotiations, thereby reducing signaling overhead and scheduling complexity.
3Reliability
If LTE-Advanced introduces transmission diversity for uplink control channel, then uplink control channel quality is improved, but compatibility with LTE is compromised
Solution Approach 1:
The patent designs the transmission diversity scheme using universal elements that are already present in LTE: radio resources (physical resource blocks), cyclic shifts (phase rotations in time domain), and orthogonal code sequences (Walsh codes). By combining these universal LTE elements in multiple dimensions, the scheme achieves transmission diversity functionality while maintaining full compatibility with LTE infrastructure and protocols.
Data Source
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AI summary
Each of mobile station apparatuses 2 receives downlink allocation information from a base station apparatus in a downlink control channel (PDCCH) (Step S10). Next, the mobile station apparatus 2 performs demodulation, decoding, and cyclic redundancy check (CRC) on the downlink shared channel (PDSCH) in accordance with the downlink allocation information received in Step S10 (Step S11). Next, the mobile station apparatus 2 generates an acknowledgement (ACK) or a non-acknowledgement (NACK) in accordance with the result of the cyclic redundancy check (CRC) in Step S12 (Step S12). Next, the mobile station apparatus 2 selects the lowest number and the second lowest number of the numbers of the control channel elements (CCEs) in which the downlink allocation information is received (Step S13). Next, based on the selected numbers, the mobile station apparatus 2 obtains a physical resource block (PRB), as well as a cyclic shift and an orthogonal code sequence in the time domain for each transmission antenna, and spreads the acknowledgement (ACK) or the non-acknowledgement (NACK) and the uplink pilot channel (Step S14). Next, the acknowledgment (ACK) or the non-acknowledgement (NACK) and the uplink pilot channel after the code spread are arranged in the physical resource block (PRB) obtained for the antenna, and then are transmitted to the base station apparatus (Step S15). Thereby, the mobile station apparatus transmits the signals in consideration of compatibility with LTE by using the same channel as in LTE to the maximum extent, and thus a transmission diversity gain can be obtained.