PDCCH Robustness via DCI Format Alignment
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Solution Overview
Problem
The imbalance in PDCCH formats for downlink (DL) and uplink (UL) communication in LTE networks leads to degradation in voice quality and handover disruptions, particularly at the cell edge, due to the larger size of DL formats compared to UL formats, resulting in issues like missed handover commands.
Innovation Solution
A method in a base station to determine interference levels using signal-to-noise-ratio (SNR) and adjust the aggregation level for transmitting messages, employing DCI Format 1A with transmit diversity for downlink signal radio bearer assignments, ensuring message robustness and alignment with uplink message formats to mitigate interference and improve handover reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If DCI format 2A is used for downlink messages to achieve scheduling flexibility and MIMO support, then transmission capability is improved, but message size increases causing imbalance with uplink formats and degradation at cell edge
Solution Approach 1:
The patent changes the DCI format parameter from format 2A to format 1A for downlink handover messages. This parameter change reduces the message size to match uplink format sizes, improving the balance between DL and UL PDCCH formats and enhancing reliability at the cell edge while maintaining adequate scheduling flexibility through the format 1A structure.
2Adaptability or versatility
If DCI format 2A is used for downlink messages, then MIMO transmission support is improved, but message size becomes larger than uplink formats causing voice quality degradation
Solution Approach 1:
The patent changes the DCI format parameter from format 2A to format 1A for downlink handover messages. This parameter change reduces the message size to match uplink format sizes, eliminating the imbalance that causes voice quality degradation at the cell edge, while MIMO support is maintained through separate physical layer mechanisms.
3Loss of information
If larger DCI format 2A is used for downlink, then more information can be transmitted, but imbalance with uplink formats leads to missed handover commands
Solution Approach 1:
The patent changes the DCI format parameter from format 2A to format 1A for downlink handover messages. This parameter change equalizes the message size with uplink formats, ensuring balanced robustness against interference and reducing the probability of missed handover commands, while essential information is maintained through optimized field configurations.
Data Source
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AI summary
A method performed in a base station includes the base station determining a level of interference in a channel between the base station and the wireless communication device based on a signal-to-noise-ratio (SNR) in the channel. The base station determines, in accordance with the determined interference, whether to use a predetermined power level to transmit a message to the wireless communication device. In response to determining to use the predetermined power level, the base station further determines whether the wireless communication device requires downlink signal radio bearer (SRB) assignments. In response to determining that the wireless communication device requires the downlink signal radio bearer assignments, the base station transmits the message to the wireless communication device using a downlink control information (DCI) message format having a same size as a message format used for uplink messages.