Open Loop Antenna Transmit Diversity for Dedicated Pilot Channels
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Solution Overview
Problem
Current 3GPP systems face significant degradation in service quality for mobile stations not supporting transmit diversity modes, as enabling transmit diversity for unsupported stations results in interference and loss of demodulation performance, preventing capacity and quality improvements until all user equipment fully supports the STTD scheme.
Innovation Solution
Modifying the open loop transmit diversity mode to enable it only for user equipment equipped to process signals from multiple antennas, by transmitting selected channels with dedicated pilots from multiple antennas and common channels from a single antenna, allowing user equipment to use dedicated pilots for channel estimation and maintaining the CPICH as a phase reference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transmit diversity is enabled for all channels including common channels, then capacity and service quality are improved for user equipment supporting transmit diversity, but performance degrades for user equipment not supporting transmit diversity due to interference and loss of demodulation performance
Solution Approach 1:
The patent segments the transmission channels into two categories: common channels (transmitted from a single antenna) and dedicated channels with dedicated pilots (transmitted from multiple antennas using transmit diversity). This segmentation allows the system to apply transmit diversity selectively, improving capacity for diversity-capable UEs while maintaining compatibility with non-diversity UEs that rely on common channels.
Solution Approach 2:
The patent applies different transmission qualities to different channel types. Common channels maintain single-antenna transmission for universal compatibility, while dedicated channels with dedicated pilots utilize multi-antenna transmit diversity for enhanced performance. This local differentiation resolves the contradiction by optimizing each channel type for its specific requirements.
2Reliability
If transmit diversity is applied to common channels, then user equipment can benefit from diversity gain, but user equipment not supporting transmit diversity experiences significant degradation in demodulation performance and synchronization
Solution Approach 1:
The patent separates common channels from dedicated channels in terms of transmit diversity application. Common channels are transmitted from a single antenna to avoid interference with non-diversity UEs, while dedicated channels with dedicated pilots use transmit diversity to provide reliability benefits to supporting UEs without affecting others.
Solution Approach 2:
Dedicated pilots serve as an intermediary mechanism that enables transmit diversity on dedicated channels without requiring changes to common channels. These dedicated pilots allow diversity-capable UEs to estimate channel conditions for multiple antennas while non-diversity UEs continue to use common channels for synchronization and basic operations.
3Productivity
If all deployed user equipment must support STTD to enable transmit diversity, then transmit diversity can be fully utilized, but this prevents deployment until all user equipment is upgraded
Solution Approach 1:
The patent divides the system into diversity-capable and non-diversity UEs, allowing the network to simultaneously support both types. Transmit diversity is activated for dedicated channels with dedicated pilots for diversity-capable UEs, while common channels maintain single-antenna transmission for compatibility with existing non-diversity UEs.
Solution Approach 2:
The patent introduces dynamic adaptability where the network can selectively enable transmit diversity on a per-channel basis. This dynamic approach allows the system to adapt to the capabilities of different UEs, enabling gradual deployment of transmit diversity without requiring all UEs to support STTD from the outset.
Data Source
AI summary
The use of the STTD is enabled in a network so that the common channels (CPICH etc.) do not need to be transmitted using transmit diversity, but the STTD can be enabled only for channels having dedicated pilots and which are intended for the UEs supporting this functionality. Other UEs not supporting transmit diversity can use the common channels as usual. In normal transmit diversity operation the UE will use the CPICH transmitted from both antennas as a phase reference. In the proposed method some of the common channels including CPICH are transmitted without transmit diversity even though the STTD is used on channels having dedicated pilots and which are intended for the UEs supporting this functionality.