Grant Loss Detection in Wireless Control Channels
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Solution Overview
Problem
Wireless communication networks, such as LTE, face inefficiencies due to the lack of direct reception quality feedback for control channels, leading to suboptimal adaptation of the Physical Downlink Control Channel (PDCCH) and subsequent network inefficiencies.
Innovation Solution
A method and apparatus for detecting grant loss in wireless communication networks, allowing for the tracking and compensation of link adaptation values for the downlink control channel and controlling Hybrid Automatic Repeat Request (HARQ) processing, by determining erasure events corresponding to scheduling grants and adjusting coding rates and transmit power accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PDSCH feedback is used to drive PDCCH outer loop control, then the control algorithm can be implemented, but the adaptation becomes suboptimal when channel conditions for PDCCH and PDSCH diverge
Solution Approach 1:
The patent implements a feedback mechanism where the UE sends ACK/NACK signals for PDCCH grant reception status. The eNodeB uses this direct feedback to adjust PDCCH transmission parameters (coding rate, power) through outer loop control, replacing the indirect PDSCH feedback approach. This enables accurate adaptation to actual PDCCH channel conditions.
Solution Approach 2:
The patent introduces an intermediary indicator (ACK/NACK signal) that directly represents PDCCH reception quality. This intermediary provides the eNodeB with actionable information about grant delivery status, enabling precise control of PDCCH transmission parameters without relying on PDSCH performance as a proxy.
2Measurement precision
If direct reception quality feedback is implemented for PDCCH, then grant loss detection becomes possible, but the system complexity increases
Solution Approach 1:
The patent reuses existing HARQ ACK/NACK signaling infrastructure for the dual purpose of both data acknowledgment and PDCCH grant reception feedback. This multi-functional use of existing mechanisms provides direct PDCCH quality measurement without adding dedicated feedback channels or complex new signaling protocols.
Solution Approach 2:
The system uses the UE's own HARQ acknowledgment signals to simultaneously indicate both data reception status and control channel grant reception status. The UE self-services the network by providing the necessary feedback information through existing uplink signaling resources, eliminating the need for separate feedback mechanisms.
3Ease of manufacture
If PDCCH is adapted based on PDSCH feedback, then implementation is straightforward, but network efficiency decreases due to suboptimal adaptation
Solution Approach 1:
The patent implements direct PDCCH feedback through UE ACK/NACK signals that explicitly indicate grant reception status. The eNodeB uses this feedback in an outer loop control algorithm to adjust PDCCH coding rate and power, enabling adaptive optimization that directly responds to actual PDCCH channel conditions rather than relying on PDSCH performance proxies.
Solution Approach 2:
The patent introduces dynamic adaptation of PDCCH transmission parameters (coding rate, power) based on real-time feedback about grant reception success. The system transitions from static or indirectly-adapted PDCCH parameters to dynamically optimized parameters that respond to changing PDCCH channel conditions, improving network efficiency.
Data Source
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AI summary
The present invention provides a method and apparatus for improving wireless communication network performance and efficiency, based on detecting the occurrence of grant loss in relation to the transmission of scheduling grants to mobile terminals over a downlink control channel. Grant loss detection is based on detecting erasure events corresponding to the transmitted scheduling grants, and the incidence of grant loss with respect to a given mobile terminal can be tracked and used to compensate the control value(s) used for link adaptation of the downlink control channel, with respect to that terminal. Additionally, or alternatively, when a given grant is determined to be lost, a new grant is sent and the HARQ redundancy version is reset for the newly scheduled transmission.