UE Feedback Vector for SLNR Precoding Latency
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Solution Overview
Problem
Existing SLNR pre-coding methods in wireless communication networks are limited by the need for full channel information, proprietary UE detection algorithms, and high computational complexity, particularly in multi-cell systems, leading to processing latency and traffic load issues.
Innovation Solution
A method where user equipment (UE) determines a feedback vector based on received transmissions and transmits it to the radio base station (RBS), allowing the RBS to calculate an SLNR pre-coding vector for subsequent transmissions, exploiting temporal channel correlation to improve downlink performance without iterative procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If iterative SLNR pre-coding is used to jointly optimize precoder and receiver, then sum rate performance is improved, but processing latency and computational complexity increase
Solution Approach 1:
The patent applies preliminary action by having the UE estimate the effective channel and determine the combining vector in advance before the RBS performs pre-coding. This allows the RBS to use the pre-computed combining vector directly without needing to perform iterative optimization, thereby reducing processing latency while maintaining improved sum rate performance.
Solution Approach 2:
The patent extracts the receiver optimization function from the iterative joint optimization process and implements it separately at the UE side. The UE determines the combining vector based on the effective channel estimation, and this extracted receiver component is then used by the RBS for pre-coding, eliminating the need for iterative computation at the RBS.
2Productivity
If iterative SLNR pre-coding is used to jointly optimize precoder and receiver, then sum rate performance is improved, but computational complexity increases
Solution Approach 1:
The patent applies preliminary action by having the UE estimate the effective channel and determine the combining vector in advance before the RBS performs pre-coding. This allows the RBS to use the pre-computed combining vector directly without needing to perform iterative optimization, thereby reducing processing latency while maintaining improved sum rate performance.
Solution Approach 2:
The patent extracts the receiver optimization function from the iterative joint optimization process and implements it separately at the UE side. The UE determines the combining vector based on the effective channel estimation, and this extracted receiver component is then used by the RBS for pre-coding, eliminating the need for iterative computation at the RBS.
3Productivity
If full channel information is required for iterative SLNR pre-coding, then optimization performance is improved, but traffic load at X2 interface increases in multi-cell systems
Solution Approach 1:
The patent applies local quality by having each UE independently determine its own combining vector based on its local effective channel estimation. Each UE processes only its own channel information locally without needing to exchange full channel matrices with other cells, thereby reducing traffic load at the X2 interface while maintaining optimization performance for each user.
4Device complexity
If conventional SLNR pre-coding is used, then device complexity is reduced, but downlink performance deteriorates
Solution Approach 1:
The patent applies feedback by having the UE determine the combining vector based on the effective channel estimation and provide this information to the RBS. The RBS then uses this feedback combining vector to perform pre-coding, creating a feedback loop that improves downlink performance without requiring complex iterative optimization at the RBS side.
Data Source
AI summary
A user equipment, UE, (300), a radio base station, RBS, (400) and a respective method (100) and (200) therein for joint transmit and receive procedure are provided. The method (100) in the UE comprises receiving (110) at a time slot n, a first transmission from the RBS, the transmission comprising a first pre-coded symbol; and estimating (120) a real channel referring to a transfer function of the channel and an effective channel referring to the real channel adjusted by transmission weights for the received first transmission. The method further comprises determining (130) a combining vector based on the effective channel, and determining (140) a feedback vector based on the combining vector and the real channel. The method comprises transmitting (150) the feedback vector to the RBS, to be used by the RBS for determining an SLNR pre-coding vector for a second transmission to the UE in a subsequent time slot.