Joint Space-Time Optimum Filters for Interference Cancellation
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Solution Overview
Problem
Current Global System for Mobile Communications (GSM) cellular systems face challenges in addressing co-channel interference (CCI) on the mobile station side and meeting Downlink Advanced Receiver Performance (DARP) requirements, with existing solutions not providing sufficient interference cancellation and channel impulse response estimation.
Innovation Solution
A mobile wireless communications device with a virtual antenna and a space-time filter circuit that jointly estimates space-time filter weights and channel impulse response, using a multi-channel, space-time filter circuit with a matched filter circuit for adaptive and optimal interference cancellation, and an auto-switching strategy to optimize performance in varying noise conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single channel structures and pre-filters are used for interference cancellation, then some channel impulse response estimation is provided, but sufficient interference cancellation and channel impulse response estimation are not achieved
Solution Approach 1:
The patent combines multiple channels into a multi-channel structure where signals from multiple antennas are processed together. This merging allows the system to achieve both sufficient interference cancellation and accurate channel impulse response estimation by utilizing the spatial diversity and correlation information across multiple channels simultaneously, rather than processing each channel independently.
Solution Approach 2:
The patent introduces a spatial dimension by using multiple antennas and processing signals in the space-time domain. This dimensionality change from single-channel temporal processing to multi-channel space-time processing enables the system to separate interference from desired signals more effectively and estimate channel responses with higher precision through spatial filtering techniques.
2Reliability
If maximization of signal-to-interference is used to design jointly a single channel space-time filter and CIR estimation, then interference reduction is achieved, but device complexity increases
Solution Approach 1:
The patent segments the complex joint optimization problem into separate processing stages: first performing multi-channel signal filtering to reduce interference, then estimating channel impulse responses from the filtered signals. This segmentation reduces computational complexity by avoiding the need to simultaneously optimize all parameters, while still achieving good signal-to-interference ratio through the staged processing approach.
3Reliability
If virtual antenna array is used to increase number of antenna elements, then interference cancellation capability is improved, but device complexity increases
Solution Approach 1:
The patent creates virtual antenna elements by processing signals from a smaller number of physical antennas through mathematical transformations and signal processing techniques. These virtual antennas are copies or synthesized versions that simulate the response of additional physical antennas, enabling the system to achieve interference cancellation capability equivalent to having more physical antennas without the corresponding increase in hardware complexity.
Data Source
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AI summary
A mobile wireless communications device may include a portable housing, at least one virtual antenna carried by the portable housing, and a space-time filter circuit carried by the portable housing for filtering a communications signal received by the at least one virtual antenna by jointly estimating space-time filter weights and at least one channel impulse response (CIR). The mobile wireless communications device may further include a matched filter circuit carried by the portable housing downstream from the space-time filter circuit and having a filter response that is provided by a channel impulse response estimation from the space-time filter circuit.