Partial CQI Feedback for Wireless Uplink Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communication systems, especially in OFDMA and SC-FDMA, the limited resources for CQI feedback in uplink control channels result in limited coding gain, making it challenging to support dynamic scheduling and MIMO transmission effectively, particularly for cell-edge UEs with coverage issues.
Innovation Solution
Implementing partial CQI feedback by dropping MCS/PMI in subframes where RI is transmitted, allowing separate RI and MCS/PMI feedback schemes, which enables frequency diversity and reduces the overall CQI information bits, thereby improving detection performance and coding gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If full CQI feedback (including MCS/PMI and RI) is transmitted in the same subframe, then complete channel quality information is provided for MIMO scheduling, but the number of CQI bits increases and coding gain decreases
Solution Approach 1:
The CQI feedback is segmented into two separate schemes: one for RI feedback and another for MCS/PMI feedback. This segmentation allows each feedback type to be optimized independently, with RI transmitted in specific subframes and MCS/PMI transmitted in other subframes, thereby reducing the total number of bits transmitted simultaneously and improving coding gain while maintaining complete channel quality information over time.
Solution Approach 2:
The patent implements periodic feedback mechanisms where RI and MCS/PMI are transmitted in alternating or separated periodic subframes. This periodic separation ensures that complete CQI information is provided over multiple transmission cycles while maintaining reliable coding in each individual transmission, resolving the contradiction between information completeness and coding reliability.
2Adaptability or versatility
If CQI feedback resources are increased to support dynamic scheduling and MIMO, then scheduling flexibility improves, but uplink control channel resources are consumed
Solution Approach 1:
By segmenting CQI feedback into separate RI and MCS/PMI transmission schemes with different periodicities and resource allocations, the patent enables dynamic scheduling and MIMO support while efficiently managing uplink control resources. Each segment can be optimized for its specific purpose without consuming excessive overall resources.
Solution Approach 2:
The patent introduces dynamic adaptability by allowing the network to configure different feedback modes and periodicities based on channel conditions and scheduling requirements. This dynamic approach enables the system to provide necessary scheduling flexibility while adapting resource consumption to actual network needs rather than allocating maximum resources continuously.
3Measurement precision
If cell-edge UEs transmit full CQI feedback, then channel quality information accuracy improves, but detection performance deteriorates due to limited resources
Solution Approach 1:
The segmentation of CQI feedback into separate RI and MCS/PMI transmissions with optimized periodicity and resource allocation significantly improves detection performance for cell-edge UEs. By reducing the number of bits transmitted in each subframe and optimizing the timing of transmissions, the patent maintains channel quality information accuracy while overcoming the detection performance limitations that would result from transmitting all CQI bits simultaneously under resource constraints.
Data Source
AI summary
Within a wireless network, feedback information from user equipment (UE) to a control node (eNodeB) is necessary to support various functions. A UE receives an allocation from the eNodeB comprising a plurality of periodic transmission instances for a channel quality indicator (CQI) and a schedule comprising a plurality of periodic transmission instances for a rank indicator (RI), wherein the CQI comprises RI and other CQI fields. The UE then transmits an RI without transmitting the other CQI fields in a transmission instance allocated for both RI and other CQI fields.