Uplink CQI Feedback for MBMS Link Adaptation
Solution Overview
Problem
Current wireless communication systems, particularly in the 3GPP HSPA evolution, face challenges with link adaptation in Cell_FACH and UTRAN paging states due to limited uplink feedback, leading to inefficient resource allocation and power setting for MBMS, resulting in unnecessary interference and potential reception issues for users.
Innovation Solution
A method that allows link adaptation and power adjustment for HS-DSCH channels without dedicated CQI reports from all receivers, using a broadcasted CQI value for resource allocation and power setting, with receivers only reporting reduced link quality, and an outer loop power control to maintain desired coverage and reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If FACH channel uses conservative modulation and coding to reach all UEs at cell edge, then coverage is improved, but resource consumption increases
Solution Approach 1:
The patent implements dynamic link adaptation by allowing the Node B to adjust modulation and coding schemes based on CQI feedback from UEs. This transforms the static conservative transmission into a dynamic system that adapts to actual channel conditions, achieving both coverage and resource efficiency
Solution Approach 2:
The patent introduces CQI feedback mechanism where UEs report channel quality to the Node B, which then adjusts transmission parameters accordingly. This feedback loop enables the system to optimize resource allocation while maintaining coverage, resolving the contradiction between conservative transmission and resource consumption
2Speed
If HS-DSCH channel is used for MBMS to achieve higher bit-rates, then data rate is improved, but uplink feedback capability deteriorates
Solution Approach 1:
The patent makes the HS-DSCH channel multi-functional by enabling it to carry both MBMS data and support CQI feedback mechanisms. Through uplink shared channels, UEs can provide channel quality information even when receiving MBMS services, allowing the system to maintain high data rates while acquiring necessary feedback for link adaptation
Solution Approach 2:
The patent segments the feedback mechanism from the data channel by using separate uplink shared channels for CQI reporting while maintaining HS-DSCH for MBMS data transmission. This separation allows the downlink to achieve high bit-rates while the uplink provides necessary feedback information
3Adaptability or versatility
If dedicated CQI reporting is implemented in FACH/paging states, then link adaptation is improved, but system complexity increases
Solution Approach 1:
The patent implements partial link adaptation by enabling CQI reporting only when necessary (when UEs are in Cell_DCH state or when uplink shared resources are available), rather than requiring continuous dedicated feedback. This partial approach provides sufficient link adaptation capability without the full complexity of dedicated CQI reporting in all states
Data Source
AI summary
A method for transmitting data flows between a network element and a number of receivers over a first channel. The method comprises the steps of: performing a link adaptation for the transmission of a data flow by said network element, and transmitting the data flow, transmitting an indication of a channel quality required for reception of the data flow on a second channel, receiving by said receivers said indication of channel quality, measuring a link quality by said receivers by monitoring a pilot channel, comparing said measured link quality with said received indication of the channel quality, and transmitting to said network element result of said comparison of said measured link quality with said received indication of the channel quality, if said result is lower than a predetermined value. The invention also relates to a network element and a user equipment.