NodeB Interference Cancellation Using Time-Sliced Uplink Decoding
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Solution Overview
Problem
In wireless communication systems, multi-user interference in uplink channels hampers successful decoding of data channels, leading to reduced cell capacity and data throughput, as existing interference cancellation methods are inefficient in removing interference effectively.
Innovation Solution
Implementing methods and architectures at NodeB receivers to cancel interference in physical control and data channels by demodulating and combining multi-path components of baseband antenna signals, using techniques like maximal ratio combining, HARQ combining, and error correction to enhance decoding success rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional interference cancellation methods are used, then multi-user interference is partially reduced, but decoding success rate remains low and cell capacity is limited
Solution Approach 1:
The received signal is divided into multiple time slices, with each slice dedicated to a specific user. This segmentation allows the receiver to process and decode signals from different users separately in time, eliminating multi-user interference and significantly improving decoding success rate while enabling support for more users (increased cell capacity).
Solution Approach 2:
The system performs preliminary interference cancellation by reconstructing and subtracting known user signals from the received mixture before decoding. This preliminary action removes dominant interference components, making subsequent decoding of remaining users more reliable and improving overall cell capacity.
2Productivity
If multiple users transmit simultaneously in the same frequency band, then data throughput increases, but multi-user interference increases and hamper decoding
Solution Approach 1:
The system uses periodic time-sliced transmission where users transmit in alternating time intervals rather than continuously simultaneously. This periodic time-division approach maintains high data throughput by keeping all users active while eliminating interference through temporal separation, allowing the receiver to process each user's signal during their dedicated time slice.
3Reliability
If interference cancellation is implemented, then decoding success improves, but receiver complexity increases
Solution Approach 1:
By segmenting the received signal into time slices for different users, the receiver processes each user's signal separately rather than dealing with the full multi-user mixture simultaneously. This segmentation simplifies the interference cancellation process and reduces receiver complexity compared to attempting to decode all users from a mixed signal.
Solution Approach 2:
The receiver performs preliminary interference cancellation by reconstructing and removing known user signals before attempting to decode unknown users. This preliminary action simplifies the subsequent decoding process by reducing the interference environment, making the overall receiver architecture more manageable despite the added cancellation step.
Data Source
AI summary
Example embodiments include methods of interference cancellation at NodeB receivers of baseband antenna signals including physical channels. The methods include canceling interference from a received baseband antenna signal by removing a reconstructed baseband signal from the processed received baseband antenna signal. The processed reconstructed baseband signal includes users whose physical data channel signals were successfully decoded. Methods also include removing interference from a received baseband signal to form an interference cancelled baseband signal that will be processed by the receiver. The interference cancelled baseband signal is the received baseband antenna signal minus users' signal interference contributions whose demodulated physical data channel signals have a determined user symbol energy value that exceeds a threshold. Methods further include removing interference from a user's signal to be error corrected. The interference is symbol interference from an earlier successfully decoded user's symbols. The user symbol interference is determined by cross correlations.