E-DCH Frame Timing Offset for CELL_FACH to CELL_DCH Transition Latency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The transition from CELL_FACH to CELL_DCH in wireless communications involves significant latency and resource overhead, particularly in high-speed packet access scenarios, due to difficulties in initializing the F-DPCH frame timing and power control, which delays power control updates and affects E-DCH performance.
Innovation Solution
The method involves determining the start of an E-DCH frame based on a relative F-DPCH timing offset signaled to the WTRU, allowing for earlier transmission of the DPCCH power control preamble and optimizing E-DCH frame alignment to minimize latency and power synchronization issues, while dynamically allocating access slots for R8 and R99 WTRUs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the WTRU transitions from CELL_FACH to CELL_DCH to support high-speed data services, then the data service quality is improved, but the transition latency and network resource overhead increase significantly
Solution Approach 1:
The patent segments the transition process by allowing E-DCH transmission in CELL_FACH state before full CELL_DCH transition is complete. This enables partial use of CELL_DCH resources (E-DCH) while remaining in CELL_FACH, thereby reducing the need for complete state transition and associated latency.
Solution Approach 2:
The patent implements preliminary action by performing E-DCH transmission in advance within CELL_FACH state. The WTRU can transmit data using E-DCH resources before the formal CELL_DCH transition is finalized, effectively preparing the data service in advance and reducing overall transition latency.
2Reliability
If the F-DPCH frame timing is initialized during CELL_FACH to CELL_DCH transition, then the power control can be established, but the initialization complexity and latency increase
Solution Approach 1:
The patent applies preliminary action by determining the F-DPCH frame timing and initiating power control procedures while the WTRU is still in CELL_FACH state, before the formal CELL_DCH transition. This preliminary setup reduces the complexity and time required for timing initialization during the actual transition.
Solution Approach 2:
The WTRU performs self-service by autonomously determining its F-DPCH frame timing offset relative to the P-CCPCH frame timing without requiring complex network coordination. The WTRU calculates the timing offset based on available synchronization information, reducing network overhead and initialization complexity.
3Stability of the object's composition
If the WTRU waits for F-DPCH frame timing alignment before transmitting E-DCH data, then the power control loop is stable, but the transmission latency increases
Solution Approach 1:
The patent implements preliminary action by determining the F-DPCH frame timing and preparing power control parameters while in CELL_FACH state, before E-DCH transmission begins. This preliminary preparation allows the WTRU to start E-DCH transmission sooner without compromising power control stability.
Solution Approach 2:
The patent applies dynamics by allowing the WTRU to dynamically adjust its transmission timing based on the determined F-DPCH frame timing offset. The WTRU can flexibly align E-DCH transmissions with the power control loop requirements while minimizing waiting time, rather than strictly waiting for perfect alignment.
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
A method and apparatus for radio link synchronization and power control in CELL_FACH state and idle mode are disclosed. A wireless transmit/receive unit (WTRU) transmits a random access channel (RACH) preamble and receives an acquisition indicator acknowledging the RACH preamble via an acquisition indicator channel (AICH) and an index to an enhanced dedicated channel (E-DCH) resource. The WTRU determines a start of an E-DCH frame. An F-DPCH timing offset is defined with respect to one of the RACH access slot and an AICH access slot carrying the acquisition indicator. A relative F-DPCH timing offset may be signaled to the WTRU and the WTRU may determine a start of an E-DCH frame based on the relative F-DPCH timing offset and timing of an AICH access slot including the acquisition indicator. The WTRU may transmit a dedicated physical control channel (DPCCH) power control preamble before starting an E-DCH transmission.