Multi-AP Beamforming for Simultaneous Uplink Downlink
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Solution Overview
Problem
Current wireless communication systems face challenges in achieving high spectrum efficiency due to the complexity of self-interference cancellation and synchronization requirements in simultaneous transmit and receive (STR) and multi-AP transmission techniques, which hinder the effective reuse of bandwidth within a cell.
Innovation Solution
The method involves using multiple access points (APs) for simultaneous uplink and downlink transmissions, where one AP acts as a Master AP for beamforming and scheduling, while other APs, referred to as Slave APs, receive uplink transmissions, thereby reducing self-interference and eliminating the need for tight synchronization, and utilizing beamforming to isolate APs and stations, allowing for efficient spectrum reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If simultaneous transmit and receive (STR) is used to improve spectrum efficiency, then spectrum efficiency is improved, but self-interference cancellation complexity increases significantly
Solution Approach 1:
The system divides the AP into multiple functional units with dedicated roles: some units are assigned exclusively for transmission while others are assigned exclusively for reception. This segmentation eliminates self-interference by ensuring that transmitting and receiving functions are separated in space, allowing STR operation without complex cancellation mechanisms.
Solution Approach 2:
The patent introduces spatial separation as an intermediary mechanism between transmission and reception functions. By using multiple radio units positioned in space and applying spatial beamforming, the system creates physical and directional separation between uplink and downlink paths, acting as a mediator that eliminates the need for complex self-interference cancellation.
2Productivity
If multi-AP transmission is used to improve spectrum efficiency, then spectrum efficiency is improved, but synchronization requirements become very strict
Solution Approach 1:
The system segments the multi-AP operation into independent scheduling domains where each AP can operate autonomously according to its assigned uplink or downlink function. This eliminates the need for tight synchronization between APs, as they operate in coordinated but independent fashion with clear role differentiation.
Solution Approach 2:
Instead of requiring APs to synchronize their operations tightly, the patent inverts the approach by having a single AP (the scheduling AP) make all scheduling decisions and assign roles to other APs. The scheduled APs then execute their assigned functions independently, reversing the traditional synchronization model.
3Productivity
If bandwidth is reused across multiple cells to improve spectrum efficiency, then spectrum efficiency is improved, but interference between cells increases
Solution Approach 1:
The patent applies local quality by using spatial beamforming to create directionally focused transmission patterns. Each radio unit transmits with tailored beam patterns that concentrate energy toward intended receivers while creating nulls in directions of potential interferers, including other APs and cells, thus enabling bandwidth reuse with minimal interference.
Solution Approach 2:
The patent converts the potential harm of simultaneous transmissions into benefit by using the known spatial relationships and channel state information to design beamforming patterns that actively steer signals and nulls. What would normally be interference becomes a controllable parameter that is exploited to improve overall system performance through coordinated spatial filtering.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances spectrum efficiency by balancing transmission powers and using beamforming to minimize interference, achieving a high signal-to-interference-plus-noise ratio (SINR) for both uplink and downlink transmissions without the complexity of self-interference cancellation and synchronization, thus optimizing resource usage within a cell.
Implementation Method 1
assigning antenna weights for an array antenna of the first access point to provide beamforming transmission of the downlink transmission towards the second station and a null towards the second access point
Data Source
AI summary
A method of a first access point and an access point arranged to provide wireless communication access for a wireless communication system are disclosed. The method comprises determining that a first station is to transmit uplink data in an uplink transmission at a first frequency band in the unlicensed spectrum, assigning a second access point for receiving the uplink transmission, wherein the second access point is covering at least an overlapping area with a coverage area of the first access point, determining a second station targeted for downlink transmission, wherein the downlink transmission is scheduled for at least partly simultaneous transmission with the uplink transmission from the first station and at least partly overlapping the first frequency band, wherein a selection of the second station targeted for downlink transmission is based on a spatial relationship between the first and second stations, assigning antenna weights for an array antenna of the first access point to provide beamforming transmission of the downlink transmission towards the second station and a null towards the second access point, and transmitting the downlink transmission using the antenna weights. The access point is arranged to perform the method.