Relative Grant Signaling for Uplink HARQ Rate Control
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Solution Overview
Problem
In mobile communication systems using E-DCH, the downlink signaling overhead is high due to the need to transmit scheduling grants for controlling uplink data rates, which limits system performance and increases interference among uplink signals.
Innovation Solution
The method involves generating and interpreting a Relative Grant (RG) that applies to multiple HARQ processes, with a reference RG and non-reference RG, reducing the need for repeated signaling by using a common channelization code and interpreting RG values to adjust data rates efficiently, thereby minimizing downlink signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If scheduling grants are transmitted for each HARQ process to control uplink data rates, then data rate control reliability is improved, but downlink signaling overhead increases
Solution Approach 1:
The patent combines multiple scheduling grants for different HARQ processes into a single common scheduling grant transmitted on the E-RGCH. The base station transmits one scheduling grant that applies to multiple HARQ processes simultaneously, reducing the number of separate downlink signals needed while maintaining control over uplink data rates for all processes.
Solution Approach 2:
The common scheduling grant serves multiple functions by applying to multiple HARQ processes simultaneously. A single scheduling grant message performs the data rate control function for multiple parallel HARQ processes, making the signaling mechanism universal and efficient rather than requiring separate dedicated grants for each process.
2Measurement precision
If separate scheduling grants are transmitted for each HARQ process, then control precision is improved, but system throughput decreases due to increased overhead
Solution Approach 1:
Multiple separate scheduling grant transmissions are merged into a single common scheduling grant. This reduces the total number of downlink signals transmitted, freeing up downlink capacity for other data transmissions and improving overall system throughput while maintaining precise control through the unified grant structure.
Solution Approach 2:
Instead of transmitting the minimum required separate grants for each HARQ process, the system uses a partial action approach by transmitting one grant that partially controls multiple processes simultaneously. This excessive coverage in terms of control scope reduces overhead without sacrificing the necessary control precision for individual processes.
Data Source
AI summary
A method and apparatus for transmitting and receiving downlink control information in a mobile communication system supporting an uplink packet data service are provided. To transmit packet data in an HARQ mobile communication system, a second transceiver receives an RG as rate control information from a first transceiver. The second transceiver sets the allowed maximum data rate of an HARQ process to which the RG is applied to the allowed maximum data rate of an HARQ process previous to the HARQ process, if the RG indicates hold. The second transceiver transmits packet data within the set allowed maximum data rate to the first transceiver.