Precoding Vector Switching for Uplink Transmit Diversity
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Solution Overview
Problem
Current wireless communication systems face challenges in providing reliable transmit diversity over uplink channels, particularly in multiple-access networks like LTE, where peak to average power ratio (PAPR) and scheduling restrictions limit the effectiveness of transmit diversity schemes.
Innovation Solution
The implementation of a transmit diversity scheme using precoding vector switching (PVS) and frequency hopping across slots of a subframe, where precoding vectors are determined based on a received indicator to provide orthogonal transmissions and improve reliability, allowing for flexible operation in frequency hopping or non-frequency hopping modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transmit diversity schemes are implemented in uplink communication, then reliability of data transmission is improved, but peak to average power ratio (PAPR) increases
Solution Approach 1:
The patent applies parameter changes by dynamically switching between different precoding vectors based on channel conditions and frequency hopping patterns. This allows the system to adjust transmission parameters adaptively, maintaining reliability while controlling PAPR through optimized precoding selections that vary transmission characteristics across different time-frequency resources.
Solution Approach 2:
The patent implements dynamics through frequency hopping and precoding vector switching that adapt to changing channel conditions. The system dynamically adjusts transmission parameters across slots and subframes, enabling transmit diversity benefits while managing PAPR through time-varying transmission strategies rather than static diversity schemes.
2Reliability
If transmit diversity schemes are implemented in uplink communication, then reliability of data transmission is improved, but scheduling restrictions increase
Solution Approach 1:
The patent applies segmentation by dividing the uplink transmission into multiple slots within subframes, with different precoding vectors applied to different slots. This segmentation allows transmit diversity to be implemented in a structured manner that is compatible with existing scheduling frameworks, reducing the complexity burden compared to unified diversity approaches.
Solution Approach 2:
The patent implements periodic action through frequency hopping patterns and precoding vector switching that occur at regular intervals (e.g., slot boundaries). This periodic structure aligns well with existing scheduling periodicity in LTE systems, making integration easier and reducing scheduling complexity compared to aperiodic diversity schemes.
3Reliability
If frequency hopping and precoding vector switching are used, then transmit diversity is improved, but device complexity increases
Solution Approach 1:
The patent applies self-service by enabling the user equipment to autonomously select and switch between precoding vectors based on predefined criteria and received indicators, without requiring complex centralized coordination. This self-service approach reduces overall system complexity while maintaining transmit diversity benefits through distributed intelligence at the UE side.
Solution Approach 2:
The patent implements preliminary action by pre-configuring precoding vector sets and frequency hopping patterns before transmission begins. The base station provides indicators in advance that guide the UE's precoding selections, allowing the UE to prepare transmission parameters ahead of time rather than making complex real-time decisions, thus reducing operational complexity.
Data Source
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AI summary
Methods and apparatuses are provided that include providing transmit diversity for data channel transmissions. Different precoding vectors can be used over different slots of a given subframes to precode corresponding signals. The precoding vectors, in one example, can be orthogonal. In addition, using the different precoding vectors can be determined based on a user equipment receiving an indicator from a base station receiving the data channel transmissions of whether to use frequency hopping over the slots. Moreover, precoding vectors used to precode data channel transmissions can additionally or alternatively vary across subframes.