Signaling MIMO Allocations for Interference Cancellation
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Solution Overview
Problem
In CDMA systems, intersymbol interference caused by multipath propagation leads to a loss of orthogonality among signals, resulting in degraded system performance and increased interference, which existing technologies struggle to mitigate effectively.
Innovation Solution
A method is introduced where a base station communicates allocation information of codes and timeslots to mobile terminals, allowing them to build an allocation table and use this information to mitigate interference through techniques like multi-user detection and spatial diversity, enhancing signal quality and system performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If CDMA systems use spread spectrum techniques with orthogonal or pseudo-orthogonal codes to support multiple users, then system capacity increases, but intersymbol interference from multipath propagation causes loss of orthogonality and degraded system performance
Solution Approach 1:
The base station performs preliminary actions by determining and signaling code allocation information to mobile terminals before the actual data transmission occurs. This allows mobile terminals to pre-configure their interference cancellation capabilities based on known allocations, enabling them to effectively mitigate intersymbol interference and maintain signal orthogonality even in multipath environments
Solution Approach 2:
The system implements feedback mechanisms where the base station signals code allocation information to mobile terminals, which then use this information to cancel interference from other codes. This feedback loop enables mobile terminals to adapt their reception processing dynamically, improving reliability while supporting multiple users through coordinated interference management
2Measurement precision
If mobile terminals use matched filtering with assigned codes to decode signals, then signal detection accuracy improves, but interference from other codes transmitted in the same timeslot increases
Solution Approach 1:
The invention converts the harmful interference from other codes into a beneficial effect by providing mobile terminals with code allocation information. This enables them to implement interference cancellation techniques where the previously harmful signals from other codes are now used as reference signals to subtract and eliminate interference, thereby improving signal detection accuracy while maintaining support for multiple users
Solution Approach 2:
Code allocation information acts as an intermediary element between the base station and mobile terminals. This information enables mobile terminals to identify and cancel interference from other codes by providing knowledge about which codes are allocated to which terminals, effectively mediating the interference problem and improving signal detection accuracy without reducing system capacity
Data Source
AI summary
The present invention relates to demodulation of radio signals from a base station having collocated transmit antennas, and more particularly to signaling allocation information from a base station to a mobile terminal. The allocation information may include timeslot and code information of allocation to other mobile terminals. Some embodiments of the present invention facilitate a mobile terminal's ability to receive and demodulate a signal containing multiple interfering signals by communicating codes allocated to other mobile terminals.