Access Node Position-Based Precoding for Wireless Control Channels
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Solution Overview
Problem
Current wireless communication systems face inefficiencies in managing and transmitting control information, particularly in MIMO systems, where the need for accurate CSI and frequent pilot signals consumes significant radio resources, limiting the number of user nodes that can be served due to constraints on channel sounding and control channel capacities.
Innovation Solution
An access node with a transceiver and processor that determines the physical location of user nodes and distinguishes between line of sight and non-line of sight radio links, using position-based precoding with narrowband beacons to reduce the number of uplink pilots required, and employing hybrid channel matrices to support both channel-based and position-based precoding, allowing for efficient transmission of control and data signals on the same radio resource.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If non-precoded control channels are used, then implementation is simple, but radio resources are wasted and spectral efficiency is low
Solution Approach 1:
The patent applies parameter changes by transitioning from non-precoded to precoded control channels, where the precoding matrix is selected based on channel state information (CSI) parameters. This allows the system to adapt the transmission parameters to channel conditions, improving spectral efficiency while maintaining manageable complexity through predefined precoding matrices.
Solution Approach 2:
The patent implements dynamics by making the control channel precoding adaptive to channel conditions. The precoding matrix varies dynamically based on CSI feedback from user equipment, allowing the system to optimize resource utilization according to changing channel states rather than using a fixed non-precoded approach.
2Measurement precision
If frequent wideband pilot symbols are transmitted, then accurate channel estimation is achieved, but radio resources are significantly consumed
Solution Approach 1:
The patent applies partial action by transmitting only necessary pilot symbols rather than frequent wideband pilots. The system uses reduced pilot overhead combined with interpolation and prediction techniques to achieve adequate channel estimation accuracy, thereby reducing radio resource consumption while maintaining sufficient measurement precision.
Solution Approach 2:
The patent uses preliminary action by pre-defining precoding matrices and using historical channel state information to predict future channel conditions. This allows the system to prepare transmission parameters in advance based on past measurements, reducing the need for frequent new pilot transmissions.
3Productivity
If the number of user nodes is increased, then network capacity is improved, but control channel capacity becomes a limiting factor
Solution Approach 1:
The patent applies merging by combining multiple user nodes' control information into the same time-frequency resources through precoding. By using spatial multiplexing with precoded control channels, the system can serve multiple users simultaneously on overlapping resources, effectively increasing network capacity without proportionally increasing control channel resource consumption.
Solution Approach 2:
The patent introduces another dimension by utilizing the spatial domain through multiple antennas and precoding. Instead of allocating separate time-frequency resources for each user's control channel, the system exploits the spatial dimension to multiplex multiple users, thereby increasing capacity without consuming additional time-frequency resources.
4Quantity of substance
If position-based precoding with narrowband beacons is used, then uplink pilot resources are reduced, but system must handle line of sight and non-line of sight conditions
Solution Approach 1:
The patent applies dynamics by implementing adaptive precoding that changes based on radio link conditions. The system dynamically selects between position-based precoding for line of sight conditions and other precoding schemes for non-line of sight conditions, ensuring optimal performance across varying environmental scenarios while reducing uplink pilot resources.
Solution Approach 2:
The patent uses parameter changes by adjusting the precoding approach based on detected radio link characteristics. When line of sight conditions are detected, the system switches to position-based precoding with narrowband beacons; when non-line of sight conditions are detected, it employs alternative precoding methods, thereby adapting parameters to match environmental conditions.
Data Source
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AI summary
An access node in a wireless communication system that includes a transceiver and a processor. The transceiver being configured to receive one or more uplink pilots associated with a user node via a radio link. The processor is configured to determine, based on the one or more uplink pilots, a location of the user node and whether the radio link is a line of sight radio link or a non-line of sight radio link. When the radio link is a line of sight radio link, the processor determines a position based precoding vector based on the location of the user node, and generates a precoded downlink control signal based on the determined position based precoding vector. The transceiver transmits the precoded downlink control signal to the user node.