Node B Downlink Scheduling Adaptation for Wireless Channel Variations
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Solution Overview
Problem
Downlink data transmission through the FACH in wireless communication systems is not adapted to fast changes in wireless channel states and is not suitable for high-speed transmission due to limited data transmission rates.
Innovation Solution
The method involves scheduling downlink data transmission through the MAC layer of Node B, where user equipment provides measurement information for channel status, allowing dynamic adjustment of transmission power and data rate to adapt to changing channel conditions, enabling efficient data transmission via both FACH and HS-DSCH channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If downlink data transmission is scheduled by RNC through FACH, then control and management is simplified, but the system cannot adapt to fast changes in wireless channel states and transmission speed is limited
Solution Approach 1:
The patent implements dynamic scheduling by enabling Node B to perform autonomous scheduling decisions based on real-time channel quality indicators (CQI) reported by user equipment. This allows the system to adapt transmission parameters such as modulation scheme, code rate, and transport block size dynamically according to current channel conditions, resolving the contradiction between adaptability and control complexity by pushing intelligence to the edge (Node B) rather than maintaining centralized RNC control.
Solution Approach 2:
The patent introduces a feedback mechanism where user equipment measures channel quality and reports CQI values to Node B. Node B uses this feedback information to make informed scheduling decisions, adjusting transmission parameters to match actual channel conditions. This feedback loop enables the system to adapt to fast channel variations while keeping RNC involvement minimal, thus improving adaptability without significantly increasing overall system complexity.
2Speed
If FACH is used for downlink data transmission, then common channel allocation is simplified, but high speed data transmission is not suitable due to limited data transmission rate
Solution Approach 1:
The patent makes Node B's scheduling function universal by enabling it to handle multiple transport channels (FACH and HS-DSCH) and make unified scheduling decisions based on channel conditions. The scheduling mechanism is not channel-specific but rather adapts to the appropriate channel based on requirements, allowing the system to achieve high-speed transmission when conditions permit while maintaining the simplicity of FACH for other cases, thus resolving the contradiction between transmission speed and channel flexibility.
Solution Approach 2:
The patent enables dynamic parameter changes in transmission by allowing Node B to adjust modulation schemes, code rates, and transport block sizes based on reported CQI values. This parameter adaptation allows the system to transition from lower-rate FACH transmissions to higher-rate HS-DSCH transmissions when channel conditions improve, effectively increasing data transmission rate while maintaining channel selection flexibility through parameter-driven adaptation.
3Reliability
If RNC performs scheduling of FACH, then centralized control is maintained, but the transmission is not adapted to fast change in wireless channel state
Solution Approach 1:
The patent implements preliminary action by having user equipment continuously measure and report channel quality indicators (CQI) to Node B before actual data transmission occurs. This advance information allows Node B to pre-adjust transmission parameters and make informed scheduling decisions, ensuring reliable transmission while responding quickly to channel changes. The preliminary CQI reporting mechanism bridges the gap between centralized RNC control and the need for rapid adaptation to channel variations.
Solution Approach 2:
The patent introduces CQI reporting as an intermediary mechanism that bridges the gap between RNC's centralized control and the need for fast channel adaptation. User equipment acts as an intermediary by measuring channel conditions and providing feedback to Node B, which then uses this information to make local scheduling decisions. This intermediary feedback loop enables the system to maintain RNC's centralized control architecture while achieving rapid response to channel changes through distributed intelligence at Node B.
Data Source
AI summary
Methods of transmitting data through a downlink common transport channel in a wireless communication system are disclosed. One of the methods comprises receiving measurement information transmitted from a user equipment (UE) at an upper network node (NB), forwarding control information of the common transport channel, which is acquired from the measurement information, from the upper network node (NB) to a base station, and transmitting downlink data from the base station to the user equipment (UE) through the common transport channel in accordance with the control information.