DMRS OCC Multiplication Mode Switching for LTE-A PUSCH Reception
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Solution Overview
Problem
In LTE radio communication systems, base stations face challenges in correctly receiving PUSCH due to uncertainty about whether a mobile station operates as LTE or LTE-A, particularly when OCC is used for DMRS, leading to incorrect channel estimation and reception issues.
Innovation Solution
A mobile station apparatus and base station apparatus communication system where the mobile station decodes downlink control information to determine the appropriate orthogonal code application for DMRS based on predetermined formats and RNTI, ensuring correct multiplication and transmission of DMRS signals, allowing the base station to correctly receive PUSCH.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If OCC is used for DMRS in LTE-A to reduce interference, then interference reduction is improved, but compatibility with LTE systems deteriorates because base stations cannot correctly perform channel estimation when they cannot recognize whether OCC is being used
Solution Approach 1:
The patent implements dynamic switching between two operational modes: Mode 1 (without OCC) for LTE compatibility and Mode 2 (with OCC) for LTE-A interference reduction. The base station dynamically selects the appropriate mode based on whether it has prior knowledge of OCC usage, enabling the system to adapt to different network scenarios and maintain both interference reduction capability and backward compatibility
Solution Approach 2:
The patent changes the operational parameter of the DMRS by introducing a mode indicator that switches between two states: using OCC multiplication (Mode 2) for interference reduction and not using OCC (Mode 1) for LTE compatibility. This parameter change allows the system to optimize performance based on the specific network context while maintaining reliability across different scenarios
2Adaptability or versatility
If the base station assumes OCC is not used for channel estimation, then LTE compatibility is maintained, but PUSCH reception fails in LTE-A systems where OCC is used
Solution Approach 1:
The base station dynamically adjusts its channel estimation approach based on the mode indicator. When Mode 1 is detected, the base station performs channel estimation without OCC de-multiplication, maintaining LTE compatibility. When Mode 2 is detected, the base station applies OCC de-multiplication to correctly estimate the channel, ensuring reliable PUSCH reception in LTE-A systems. This dynamic adaptation resolves the contradiction between compatibility and reliability
3Productivity
If the base station assumes OCC is used for channel estimation, then LTE-A performance is optimized, but PUSCH reception fails in LTE systems where OCC is not used
Solution Approach 1:
The system dynamically switches between OCC-based and non-OCC-based channel estimation based on the mode indicator. In LTE-A scenarios where OCC is used, the base station applies OCC de-multiplication to maximize spectrum efficiency and productivity. In LTE scenarios where OCC is not used, the base station uses standard channel estimation to ensure reliable reception. This dynamic switching prevents productivity loss in LTE-A while avoiding reception failures in LTE
Data Source
AI summary
In a radio communication system using an Orthogonal Cover Code (OCC) for a DeModulation Reference Signal (DMRS), abase station apparatus correctly receives a Physical Uplink Shared CHannel (PUSCH). If a first mode is set in which a DMRS of a PUSCH is multiplied by an OCC determined in advance or if a temporary Cell Radio Network Temporary Identifier (C-RNTI) was used for a transmission of Downlink Control Information (DCI), the DMRS of the PUSCH is multiplied by the OCC determined in advance, and if a second mode is set in which the DMRS of the PUSCH is multiplied by an OCC determined based on cyclic shift information in the DCI and if an Radio Network Temporary Identifier (RNTI) other than the temporary C-RNTI was used for a transmission of the DCI, the DMRS of the PUSCH is multiplied by the OCC determined based on the cyclic shift information in the DCI.