Multi-Carrier CQI Reporting via Single Uplink Grant
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Solution Overview
Problem
Current wireless communication systems, particularly 3GPP LTE, face inefficiencies in reporting channel quality indicators (CQI) in multi-carrier systems, leading to suboptimal radio resource utilization, as they are designed for single-carrier systems and require additional uplink grants for each carrier.
Innovation Solution
A method and apparatus for reporting channel states in multi-carrier systems that allow for efficient CQI reporting across multiple carriers without an additional uplink grant, utilizing existing 3GPP LTE structures, where CQIs can be transmitted over multiple subframes with designated offsets and reporting modes adapted for each carrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If CQIs for all carriers are reported separately, then channel quality information for each carrier is obtained, but radio resources are inefficiently used due to additional uplink grants required
Solution Approach 1:
The patent combines CQI reporting for multiple carriers into a single uplink transmission. Specifically, CQIs for multiple downlink carriers are multiplexed and transmitted together on a single uplink shared channel (PUSCH) or uplink control channel (PUCCH), eliminating the need for separate uplink grants for each carrier's CQI reporting.
Solution Approach 2:
The patent makes a single uplink grant serve multiple carriers by enabling it to trigger CQI reporting for multiple downlink carriers simultaneously. The uplink grant structure is enhanced to include carrier indicator fields that can reference multiple carriers, allowing one grant to allocate resources for CQI reporting across multiple carriers.
2Adaptability or versatility
If single carrier channel structure is used in multi-carrier system, then backward compatibility is maintained, but CQI reporting efficiency decreases
Solution Approach 1:
The patent introduces dynamic CQI reporting mechanisms for multi-carrier systems while preserving the basic single-carrier structure. The system dynamically selects which carriers to report CQI for based on current channel conditions, traffic patterns, and scheduling decisions, allowing flexible adaptation without requiring complete structural redesign.
Solution Approach 2:
The patent modifies CQI reporting parameters such as reporting periodicity, offset values, and carrier selection criteria to optimize multi-carrier performance. By adjusting these parameters dynamically, the system achieves efficient multi-carrier CQI reporting while maintaining compatibility with existing single-carrier protocols and structures.
3Reliability
If CQI reporting is performed periodically on PUCCH, then channel state is monitored regularly, but radio resource overhead increases
Solution Approach 1:
The patent implements periodic CQI reporting on PUCCH with configurable periods and offsets for different carriers. The reporting periodicity can be adjusted based on channel volatility and scheduling requirements, allowing the system to balance reliable channel state monitoring with reduced resource overhead by reporting only when necessary.
Solution Approach 2:
The patent enables selective CQI reporting where not all carriers need to report CQI in every periodic opportunity. The system can configure subset reporting where only certain carriers report CQI in each period, or use differential reporting where only changes from previous reports are transmitted, reducing overall overhead while maintaining monitoring reliability.
Data Source
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AI summary
A method and an apparatus for reporting a channel state in a multi-carrier system are provided. User equipment receives an uplink grant including an uplink resource allocation and a channel quality indicator (CQI) request via one downlink carrier from among a plurality of downlink carriers. The user equipment reports CQIs for the plurality of downlink carriers via a plurality of subframes in accordance with the CQI request.