SC-FDMA MIMO Receiver Soft Interference Cancellation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional MIMO systems face performance loss in frequency selective fading channels due to noise enhancement and lack of interference cancellation using feedback from both desired and interfering user/stream decoders, particularly in SC-FDMA uplink communications.
Innovation Solution
The implementation of parallel soft interference cancellation (P-SIC) and serial soft interference cancellation (S-SIC) processes that utilize feedback from both desired and interfering user/stream decoders to improve equalization and cancel interference, reducing complexity by scaling feedback in the user plane rather than the antenna plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional MIMO equalization is used without interference cancellation, then device complexity is reduced, but throughput performance and reliability deteriorate due to noise enhancement and interference from multiple users
Solution Approach 1:
The equalization process is segmented into multiple iterative stages. In each iteration, the receiver separately processes desired signals and interfering signals through distinct equalization chains, then combines the results. This segmentation allows interference cancellation to improve throughput while managing complexity through structured modular processing.
Solution Approach 2:
The invention implements feedback mechanisms where soft decisions from initial equalization are fed back into the equalization process. The receiver uses decoded soft symbols from previous iterations to refine interference estimation and improve subsequent equalization, creating a feedback loop that enhances throughput performance iteratively.
2Reliability
If soft interference cancellation with feedback from both desired and interfering user decoders is implemented, then reliability and throughput are improved, but device complexity increases due to additional processing requirements
Solution Approach 1:
The receiver merges the equalization of desired signals and interfering signals into a unified processing framework. By combining multiple equalization results weighted according to their reliability, the system achieves improved detection reliability while sharing computational resources across different signal processing chains, thereby managing complexity.
Solution Approach 2:
The invention implements partial interference cancellation where the receiver processes interfering signals to the extent needed to achieve sufficient reliability improvement. Rather than perfectly canceling all interference, the system performs partial cancellation that provides adequate reliability enhancement while limiting the additional processing complexity to necessary levels.
3Measurement precision
If feedback is scaled in the antenna plane, then interference cancellation accuracy is improved, but device complexity and computational load increase significantly
Solution Approach 1:
The invention changes the dimension in which feedback is scaled from the antenna plane to the user plane. Instead of scaling feedback across multiple antenna dimensions, the system scales feedback according to user-specific parameters and channel conditions, reducing the dimensional complexity while maintaining cancellation accuracy through user-oriented processing.
Solution Approach 2:
The receiver applies local quality scaling where feedback is weighted according to user-specific channel conditions and signal characteristics rather than uniform antenna-based scaling. This localized approach maintains interference cancellation accuracy for each user while reducing overall processing complexity by avoiding full antenna-plane operations.
Data Source
AI summary
A system and method are provided for Soft Interference Cancellation (SIC) in receiving Single Carrier Frequency Division Multiple Access (SC-FDMA) Multiple-Input Multiple Output (MIMO) signals. A receiver with Mr antennas accepts multicarrier signals transmitted simultaneously, with N overlapping carrier frequencies. The receiver removes a cyclic prefix (CP), and fast Fourier transforms (FFT) the multicarrier signal from each antenna, supplying Mr number of N-tone signals y. Using either parallel SIC (P-SIC) or successive SIC (S-SIC), interference is canceled in each of the Mr signals, and soft symbols are supplied for each of U layers. Interference is canceled using the P-SIC process by parallel processing the U layers in an i-th iteration, in response to feedback from an (i−1)th iteration. Alternatively, interference is canceled using the S-SIC process by sequentially processing the U layers in an i-th iteration, in the order of u0,u1, . . . , uU−1, using feedback generated from previously processed layers.