Base Station Uplink Rate Detection for Ghost Grant Interference
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Solution Overview
Problem
In HSUPA systems, false detection of absolute grants (ghost grants) by user entities can lead to excessive uplink transmissions, causing interference and instability due to unmanaged power emissions, especially in TD scheduling where resources are not available to decode transmissions, resulting in long retransmission tails and unnecessary interference.
Innovation Solution
A method in a base station that detects the rate of uplink transmissions and sends an ACK without forwarding data to the core network if the rate exceeds the granted rate, thereby preventing overload and reducing interference by managing grant levels and acknowledging successful decoding, thus stopping unnecessary transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base station sends NACK when decoding fails, then the user entity retransmits data, but this causes long retransmission tails and excessive interference when ghost grants occur
Solution Approach 1:
The patent converts the harmful effect of ghost grants (which cause unnecessary retransmissions and interference) into a beneficial outcome by detecting the anomaly and sending ACK instead of NACK. This stops the harmful retransmission cycle while maintaining reliable data transmission through upper layer protocols.
Solution Approach 2:
The patent implements a feedback mechanism where the base station monitors uplink transmission rates and compares them against granted rates. When a discrepancy is detected (indicating ghost grant), the system provides corrective feedback by sending ACK to stop retransmissions, thereby controlling interference while maintaining reliability.
2Productivity
If the base station allows user entities to transmit at high rates, then uplink throughput increases, but this causes overload situations and interference when grants are falsely detected
Solution Approach 1:
The patent performs preliminary detection of transmission rate anomalies before overload and interference occur. By monitoring the ratio between actual and granted rates, the system identifies ghost grant conditions early and takes preventive action by sending ACK, thus avoiding the harmful effects while allowing high throughput during normal operation.
Solution Approach 2:
The patent dynamically adjusts the ACK/NACK signaling behavior based on real-time detection of transmission rate conditions. When ghost grant is detected (dynamic condition), the system switches to sending ACK to stop transmissions; otherwise, it maintains normal NACK-based retransmission protocol, thereby optimizing both throughput and interference control.
3Stability of the object's composition
If the base station sends ACK without forwarding data, then retransmission tails are prevented, but this requires detecting overload situations which adds complexity
Solution Approach 1:
The patent implements a self-service detection mechanism where the base station uses its existing knowledge of granted rates and actual transmission rates to automatically detect ghost grant conditions. This self-detection capability maintains network stability without requiring complex external detection systems or additional infrastructure.
Data Source
AI summary
A method for a base station, and a base station, adapted for scheduling and receiving uplink transmissions from user entities and further forwarding data related to such transmissions to a core network, wherein the base station being adapted for transmitting serving grant signals for allowing a user entity to transmit uplink transmissions at a given maximum granted data rate, at least at a subsequent transmission opportunity. An uplink transmission from a user entity may be responded to by the base station by a not acknowledge, NACK, or an acknowledge, ACK, signal. The method comprises the steps of detecting the rate of an uplink transmission, detecting whether an overload situation exists, and if the rate exceeds the granted rate and an overload situation exists, sending an ACK to the user entity, although without forwarding any uplink data to the core network.