Distributed Antenna Beamforming via Dirty-Paper Coding
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Solution Overview
Problem
Current distributed antenna systems in coordinated cellular networks face challenges in maximizing data rates while maintaining power constraints, as existing methods for choosing beamforming vectors do not effectively maximize data rates while ensuring no interference is deposited on other users.
Innovation Solution
A method is proposed where a controller in a distributed antenna system performs dirty-paper coding and calculates optimal beamforming vectors to maximize data rates for each user, ensuring that the transmitted signal does not interfere with other users, and power is distributed efficiently across streams to meet total and per-antenna power constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional beamforming vector selection methods are used, then device complexity is reduced, but data rate maximization is not achieved
Solution Approach 1:
The system performs preliminary calculations of beamforming vectors before actual data transmission. The controller pre-computes the beamforming vectors based on channel state information and user requirements, storing them for subsequent use. This preliminary action enables the system to achieve maximum data rates without computing complexity during real-time transmission.
Solution Approach 2:
The patent replaces complex iterative optimization algorithms with a closed-form mathematical solution for beamforming vector calculation. By substituting the mechanical/iterative computation process with a direct mathematical formula involving matrix operations, the system achieves both data rate maximization and computational efficiency.
2Productivity
If beamforming vectors are optimized to maximize data rates, then interference to other users may increase, but if interference suppression is prioritized, data rate maximization is compromised
Solution Approach 1:
The patent converts the harmful interference effect into a beneficial constraint by incorporating interference suppression directly into the beamforming vector optimization criterion. The beamforming vectors are designed to maximize data rates while simultaneously suppressing interference to other users, transforming the interference problem into part of the optimization objective function.
Solution Approach 2:
The system dynamically adjusts beamforming vector parameters based on channel state information and user distribution. By changing the beamforming parameters adaptively, the system maximizes data rates for current users while maintaining interference suppression levels within acceptable thresholds for other users.
3Use of energy by moving object
If total power constraint is enforced, then energy efficiency is improved, but per-antenna power distribution flexibility is reduced
Solution Approach 1:
The patent segments the total power constraint into per-antenna power constraints, allowing independent control and optimization of power distribution across individual antennas. This segmentation enables the system to enforce overall power limits while maintaining flexibility in distributing power adaptively to different antennas based on channel conditions and user requirements.
Data Source
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AI summary
In a distributed antenna system (100) that includes a plurality of transmitters (115) and a controller (110), a method, performed by the controller (110), may be characterized by performing dirty-paper coding on downlink transmissions to users based on an order of the users, calculating beamforming vectors to provide that each of the downlink transmissions associated with each of the users does not interfere with other users, and maximizing, based on the calculated beamforming vectors, a data rate subject to a power constraint of the distributed antenna system (100).