Base Station Downlink SIR Estimation via Uplink Pilot Symbols
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Solution Overview
Problem
In wireless communication systems with high frequency reuse, the feedback overhead, delay, and errors in measuring and reporting the signal power to interference power ratio (SIR) for downlink channels lead to performance degradation, especially in cellular systems where the same channel interference is severe.
Innovation Solution
An apparatus and method that estimate the downlink SIR at the base station using a pilot symbol spread with a unique pseudo-noise code, eliminating the need for user feedback and enabling adaptive transmission based on the estimated SIR, thereby improving downlink performance without reducing uplink throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the user measures and feeds back the downlink SIR to the base station, then the base station can perform adaptive transmission, but performance degradation occurs due to feedback overhead, feedback delay, and feedback error
Solution Approach 1:
Instead of having the user measure and feed back the downlink SIR to the base station, the invention inverts the approach by having the base station measure the uplink SIR and use it for downlink adaptive transmission. This eliminates the need for downlink SIR feedback from the user side, thereby removing feedback overhead, delay, and errors while still enabling adaptive transmission based on channel conditions.
2Adaptability or versatility
If the user feeds back the measured SIR to the base station, then adaptive transmission can be performed, but feedback delay reduces system efficiency
Solution Approach 1:
The base station performs preliminary measurement of the uplink SIR using pilot signals before downlink transmission. By having the SIR information ready in advance through uplink measurement, the system can immediately perform adaptive transmission without waiting for user feedback, thereby eliminating feedback delay while maintaining adaptability.
3Adaptability or versatility
If the user feeds back the measured SIR to the base station, then adaptive transmission can be performed, but feedback overhead reduces uplink throughput
Solution Approach 1:
The invention extracts the SIR measurement function from the user side and relocates it to the base station side. By taking out the measurement responsibility from the user, the system eliminates the need for users to transmit feedback signals, thereby removing feedback overhead and preserving uplink throughput for actual data transmission.
4Reliability
If the base station measures uplink SIR using pilot symbols, then downlink adaptive transmission can be performed without feedback, but measurement precision must be sufficient
Solution Approach 1:
The invention uses pilot symbols as an intermediary to enable the base station to measure the uplink SIR. These known pilot signals transmitted by the user allow the base station to accurately estimate channel conditions and calculate SIR without requiring feedback from the user, thereby maintaining measurement precision while avoiding feedback-related problems.
Data Source
AI summary
A transmission and reception apparatus and method for use in a wireless communication system, and an apparatus and method for adaptively transmit and receive a signal according to channel state in a wireless communication system. An apparatus for adaptively performing transmission according to a state of a channel transmitted from a transmitter to at least one receiver includes a signal to interference ratio estimator for estimating a signal to interference ratio of the channel using a signal transmitted from the at least one receiver; and an adaptive transmitter for transmitting data to the at least one receiver on a basis of the estimated signal to interference ratio.