Per-Antenna Training Isolation Using Transmit-Receive Switches
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing multiple antenna communication systems face challenges in achieving accurate channel estimation and backwards compatibility due to inadequate antenna isolation during per-antenna training, leading to issues like RF leakage, phase or magnitude offsets, and glitches in power amplifiers and voltage-controlled oscillators.
Innovation Solution
The implementation of a per-antenna training technique that uses an antenna transmit/receive RF Switch and variable scaling of OFDM symbols to provide improved isolation, where only one transmit antenna is active during the long training sequence, and the others are in receive mode, with digital-to-analog converters receiving a 0-code to maintain power amplifier and RF transceiver stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If per-antenna training is implemented with sequential transmit antenna activation, then channel estimation accuracy is improved, but antenna isolation becomes insufficient leading to RF leakage
Solution Approach 1:
A transmit/receive switch is introduced as an intermediary component between the power amplifier and antenna for silent transmit antennas. This switch connects silent antennas to the receiver input port, creating an isolation path that prevents RF leakage from active antennas from corrupting channel estimation measurements on silent antennas.
2Object-affected harmful factors
If transmit antenna chains are switched on and off for isolation, then antenna isolation is improved, but power amplifier temperature stability deteriorates causing phase or magnitude offsets
Solution Approach 1:
The system dynamically configures each antenna chain's operational mode (transmit or receive) based on its role in per-antenna training. Silent transmit antennas are dynamically switched to receive mode, allowing their power amplifiers to remain in a stable state without repeated on/off cycling, thereby maintaining temperature stability and avoiding phase or magnitude offsets.
3Object-affected harmful factors
If transmit antenna chains are turned off for isolation, then antenna isolation is improved, but voltage controlled oscillator stability deteriorates causing glitches
Solution Approach 1:
The voltage controlled oscillator in silent transmit antenna chains continues to operate continuously rather than being turned off. By keeping the VCO running and switching the antenna chain to receive mode instead, the system maintains oscillator stability and avoids glitches while still achieving the necessary antenna isolation for accurate channel estimation.
4Object-affected harmful factors
If power amplifiers are repeatedly activated and deactivated, then antenna isolation is improved, but system reliability deteriorates due to excessive delays
Solution Approach 1:
The system dynamically switches silent transmit antennas to receive mode during per-antenna training, allowing power amplifiers to remain in a stable on-state without repeated activation and deactivation cycles. This dynamic reconfiguration eliminates start-up delays and excessive waiting times while maintaining the isolation necessary for accurate channel estimation.
Data Source
AI summary
Methods and apparatus are provided for per-antenna training in a multiple antenna communication system having a plurality of transmit antenna branches. A long training sequence is transmitted on each of the transmit antenna branches such that only one of the transmit antenna branches is active at a given time. The active transmit antenna branch is configured in a transmit mode during the given time and one or more of the inactive transmit antenna branches are configured in a receive mode during the given time. The transmit and receive modes are configured, for example, by applying a control signal to one or more switches.