Uplink Downlink Cell Separation for Wireless Interference
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Solution Overview
Problem
In wireless communication networks, particularly in UMTS systems, there is an imbalance in power transmission between macro and pico cells, leading to unreliable uplink communications due to the same cell being selected for both downlink and uplink operations, resulting in suboptimal radio conditions.
Innovation Solution
The method involves configuring different cells for downlink and uplink communications, where the macro cell serves as the downlink cell and the pico cell as the uplink cell, allowing for separate resource management and improved radio conditions by assigning the pico cell as the uplink serving cell based on optimal radio conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same cell is selected for both downlink and uplink operations, then the system simplifies resource management, but the uplink communication reliability deteriorates due to power imbalance between macro and pico cells
Solution Approach 1:
The patent segments the serving cell function into two independent parts: downlink serving cell and uplink serving cell. This allows different cells to be selected for downlink and uplink operations separately, optimizing each direction independently. The downlink serving cell is selected based on downlink radio conditions, while the uplink serving cell is selected based on uplink radio conditions, resolving the power imbalance issue without requiring complex unified resource management.
Solution Approach 2:
The patent applies local quality by allowing different cells to provide different serving functions based on their local characteristics. A macro cell may provide downlink serving while a pico cell provides uplink serving, or vice versa, depending on which cell offers better radio conditions for each specific direction. This localized optimization improves overall system performance by matching each serving function to the most suitable cell.
2Illumination intensity
If the macro cell is selected as the downlink serving cell due to stronger power, then downlink radio conditions improve, but uplink communication reliability deteriorates because the UE is physically closer to the pico cell
Solution Approach 1:
The patent divides the serving cell selection into separate downlink and uplink components. The downlink serving cell is independently selected to optimize downlink radio conditions, while the uplink serving cell is independently selected to optimize uplink radio conditions. This segmentation allows the system to accept that different cells will be optimal for different directions, and manages each direction separately through independent serving cell assignments.
Solution Approach 2:
The patent enables each cell to be evaluated and selected based on its local quality for the specific direction it serves. The macro cell's strong downlink power is utilized for downlink serving, while the pico cell's proximity advantage is utilized for uplink serving. This local quality optimization ensures that each serving function is performed by the cell best suited for that particular direction.
3Object-affected harmful factors
If the UE lowers its communication rate/power on uplink resources due to proximity to the pico cell, then interference to the pico cell is reduced, but the macro cell receives unreliable uplink communications
Solution Approach 1:
The patent extracts the uplink serving function from the downlink serving cell and assigns it to a separate uplink serving cell. This extraction allows the UE to transmit uplink communications at appropriate power levels determined by the uplink serving cell (pico cell) without being constrained by the downlink serving cell (macro cell). The macro cell receives reliable uplink communications because the UE transmits at power levels optimized for the actual uplink channel conditions rather than being forced to lower power to protect the pico cell.
Solution Approach 2:
The patent introduces the concept of a separate uplink serving cell as an intermediary that mediates between the UE's uplink transmissions and the network. This intermediary cell (the pico cell in this case) provides rate and power control commands specifically tailored to the uplink channel conditions, allowing the UE to transmit at optimal power levels that ensure reliable reception at the macro cell while the pico cell manages the interference through its own resource allocation and scheduling.
Data Source
AI summary
Methods and apparatuses relating to wireless communication of a user equipment (UE) are provided including receiving downlink wireless communications from multiple cells in an active set, receiving at least one of scheduling information for one or more downlink transmissions or one or more non-serving resource grants from a first cell in the active set, and receiving one or more serving resource grants for uplink communications from a second cell in the active set. In the wireless network, a second cell can be assigned as an uplink serving cell for uplink communications with the UE that is different from a first cell assigned as a downlink serving cell for downlink communications with the UE, and downlink transmissions can be scheduled from the downlink serving cell to the UE, and/or one or more serving resource grants can be transmitted from the uplink serving cell to the UE.