Uplink Reference Signal Resource Allocation for LTE Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wireless communications networks face a trade-off between throughput and feedback information, where quantizing feedback reduces performance and limits the ability to support advanced transmission schemes like LTE's downlink multi-user MIMO and CoMP, necessitating additional bandwidth without sacrificing user data bandwidth.
Innovation Solution
The method involves selecting and detecting radio resources for uplink reference signals to convey feedback information from wireless devices to base stations, using cyclic shifts and time/frequency resources, allowing for enhanced feedback without reducing data bandwidth, exemplified by using uplink Sounding Reference Signals (SRS) in LTE networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If quantized feedback information is transmitted to reduce the number of feedback bits, then the bandwidth for user data is preserved, but the network performance deteriorates and advanced transmission schemes cannot be supported
Solution Approach 1:
The patent conveys feedback information by selecting radio resources (time-frequency resources, cyclic shifts, orthogonal cover codes) for uplink reference signals rather than transmitting feedback bits directly. This transforms the feedback mechanism from a bit-stream dimension to a resource-selection dimension, enabling additional feedback capacity without consuming user data bandwidth.
Solution Approach 2:
Uplink reference signals serve dual purposes: maintaining their original function for channel estimation and quality measurement, while simultaneously conveying feedback information through resource selection. This multi-functionality allows the same signal to support both channel monitoring and feedback transmission without requiring separate dedicated feedback channels.
2Reliability
If additional bandwidth is allocated for feedback information, then network performance and advanced transmission schemes are supported, but the bandwidth available for user data transmission is reduced
Solution Approach 1:
The patent exploits the resource selection dimension (which radio resource to use for reference signal transmission) as an additional channel for feedback information. This approach adds feedback capacity in a different dimension rather than competing for the same bandwidth resources, thereby avoiding the trade-off between feedback bandwidth and user data bandwidth.
Solution Approach 2:
The system uses existing uplink reference signal resources that are already allocated for channel estimation purposes to also carry feedback information. By making existing resources serve multiple purposes, no additional bandwidth needs to be allocated specifically for feedback, thus preserving user data bandwidth while enhancing feedback capability.
3Reliability
If feedback information is transmitted via PUCCH or PUSCH using periodic schemes, then feedback is provided, but the flexibility and efficiency of resource utilization is limited
Solution Approach 1:
The patent enables dynamic feedback transmission by allowing wireless devices to select from multiple configured radio resources based on current channel conditions and feedback content. Unlike fixed periodic PUCCH/PUSCH schemes, this approach dynamically adapts resource selection to transmission needs, improving both efficiency and flexibility.
Solution Approach 2:
The base station pre-configures multiple radio resources for uplink reference signals before feedback transmission occurs. This preliminary configuration enables the wireless device to immediately select appropriate resources for feedback conveyance without requiring complex real-time resource allocation negotiations, simplifying the transmission process while maintaining flexibility.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Feedback information is conveyed between a wireless device and a base station in a cellular communications network via selection and detection of radio resources utilized for an uplink reference signal transmitted from a wireless device to a base station. In this manner, additional feedback information may be sent from the wireless device to the base station without sacrificing any bandwidth available for data transfer between the wireless device and the base station. The radio resources utilized for the uplink reference signal may include cyclic shift and/or time and frequency resources. The uplink reference signal may be an uplink sounding reference signal for a long term evolution network (LTE), or its evolution, such as LTE-Advanced.