Cooperative Precoding for Heterogeneous Wireless Networks
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Solution Overview
Problem
In two-tier cellular networks, existing precoding schemes at small-cell transmitters are independent, leading to wasted transmit dimensions and low efficiency due to dimension restrictions, causing interference and reducing spectral efficiency.
Innovation Solution
Implementing cooperative cross-tier precoding (CTP) and intra-tier precoding (ITP) using channel state information (CSI) to optimize transmit signals, increasing transmit dimensions and reducing interference between macro-cell and small-cell networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If independent precoding is used at small-cell transmitters, then device complexity is reduced, but transmit dimensions are wasted and spectral efficiency decreases
Solution Approach 1:
The patent combines independent precoding operations at multiple small-cell transmitters into a cooperative precoding scheme. By merging the precoding functions and sharing channel state information, the system achieves better spectral efficiency while maintaining manageable complexity through distributed implementation.
Solution Approach 2:
The patent exploits additional spatial dimensions by coordinating transmissions across multiple small-cell transmitters. This dimensional expansion allows the system to overcome the dimension restrictions of independent precoding, enabling more efficient use of transmit dimensions and improving spectral efficiency.
2Ease of operation
If independent precoding is used at small-cell transmitters, then ease of operation is improved, but interference management capability deteriorates
Solution Approach 1:
The patent introduces a macro-cell receiver as an intermediary that provides feedback about received interference levels. This intermediary enables coordinated interference management without requiring direct complex interaction between all small-cell transmitters, maintaining ease of operation while improving interference control.
Solution Approach 2:
The patent implements a feedback mechanism where the macro-cell receiver informs small-cell transmitters about the interference caused by their transmissions. This feedback loop enables dynamic adjustment of precoding strategies to minimize harmful interference while maintaining system simplicity.
3Device complexity
If dimension restriction is imposed on precoding, then device complexity is reduced, but throughput and capacity are limited
Solution Approach 1:
The patent overcomes dimension restrictions by utilizing the spatial dimensions provided by multiple cooperative small-cell transmitters. This multi-transmitter coordination expands the effective dimension space available for precoding, enabling higher throughput without proportionally increasing individual device complexity.
Solution Approach 2:
The patent creates a universal precoding framework that can adapt to different numbers of small-cell transmitters and channel conditions. This multi-functional approach allows the system to optimize throughput for various configurations without requiring complex transmitter-specific designs, improving overall capacity efficiently.
Data Source
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AI summary
Embodiments are provided for a cooperative cross-tier precoding (CTP) and intra-tier precoding (ITP) scheme for two-tier networks. The cooperative precoding scheme allows exploitation of extra transmit dimensions at the second-tier network, thereby increasing the achievable throughput at the second-tier network. The embodiments allow significant increase in throughput of the second-tier network due to both CTP between the second-tier network and the first-tier network, and efficient ITP between the second-tier network transmitters. The increase in transmit dimension allows for efficient linear inra-tier precoding, which significantly reduces the intra-tier interference. A processor coupled to the second-tier network transmitters is configured to perform CTP of transmit signals in the second-tier network for cancelling signal interference from the second-tier network transmitters to a first-tier network receiver, thereby generating CTP matrix information. The processor then performs, using the CTP matrix information, ITP for reducing intra-signal interference from the second-tier transmitters to corresponding second-tier receivers.