E-DCH Scheduling Information Transmission Reliability in Heterogeneous Networks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In heterogeneous networks, the reliability of scheduling information (SI) transmission is compromised during soft handover due to uplink/downlink imbalances, leading to potential failures in receiving SI by the serving E-DCH cell, especially when power control is based on the best uplink quality rather than the serving cell's requirements.
Innovation Solution
A method for user equipment (UE) to determine an enhanced-transport format combination (E-TFC) for SI transmission by receiving an E-TFC selection power backoff value from the active macro cell, adjusting E-DCH power based on acknowledgments and non-acknowledgments, and optimizing SI and data transmission using time division multiplexing, ensuring reliable SI delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If power control for DPCCH is based on the best uplink of the radio link set, then the overall uplink performance is improved, but the scheduling information transmission to the serving E-DCH cell fails due to link imbalance
Solution Approach 1:
The patent applies local quality by determining E-TFC based on the specific link quality of the serving E-DCH cell rather than the best uplink in the radio link set. This allows the UE to select appropriate transport format combinations that ensure reliable SI delivery to the serving cell, even when other cells in the RLS have better uplink conditions. The power backoff mechanism further refines this by adjusting power allocation locally for SI transmission.
Solution Approach 2:
The patent changes the parameter used for E-TFC selection from best uplink quality to serving cell-specific uplink quality. This parameter change ensures that the transport format selection is aligned with the actual requirements of the serving E-DCH cell for receiving SI, resolving the link imbalance issue while maintaining overall system performance.
2Productivity
If higher serving grant power is allocated to increase bit rate, then data transmission efficiency is improved, but SI transmission reliability deteriorates due to uplink imbalance in SHO region
Solution Approach 1:
The patent segments the power control mechanism into two parts: one for data transmission (using best uplink quality) and one for SI transmission (using serving cell quality). This segmentation allows each function to operate with appropriate power levels, ensuring both data efficiency and SI reliability without mutual interference.
Solution Approach 2:
The patent introduces an intermediary mechanism (E-TFC determination based on serving cell quality and power backoff) that mediates between the conflicting requirements of high data rate and reliable SI transmission. This intermediary ensures that SI transmission requirements are met while allowing data transmission to operate at optimal rates.
3Reliability
If time division multiplexing is used to separate SI and data transmission, then transmission reliability is improved, but transmission time increases
Solution Approach 1:
The patent employs periodic action through time division multiplexing, where SI and data are transmitted in alternating time slots. This periodic separation ensures that SI transmissions occur during dedicated time intervals when the channel conditions are optimized for control information, thereby improving reliability while accepting the time penalty as a necessary trade-off.
Data Source
AI summary
A system to obtain an enhanced-transport format combination (E-TFC) for transmitting a scheduling information (SI) in a soft handoff (SHO) to a serving enhanced Data Channel (E-DCH) cell in a heterogeneous Network (HetNet). The system comprises receiving an E-TFC selection power backoff (ESPB) value from an active macro-cell, the active macro-cell being the service E-DCH cell; determining the E-TFC based on an indicated power of a serving grant minus the received ESPB value and a set of E-TFC power offset value received from the active macro cell, if an MAC-e/i data PDU to be transmitted is multiplexed with the SI; otherwise, determining the E-TFC based on the indicated power of the serving grant and the set of E-TFC power offset value; and transmitting the MAC-e/i PDU to the active macro cell using the indicated power of the serving grant and an enhanced dedicated channel selected based on the determined E-TFC.