Channel Sounding Bandwidth Assignment for Inter-Cell Interference
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Solution Overview
Problem
Conventional channel sounding techniques in wireless communication systems, particularly for cell-edge subscriber stations, result in increased system bandwidth requirements, higher inter-cell interference due to narrower bandwidths, and do not significantly improve channel estimation accuracy.
Innovation Solution
Implementing a technique where low-geometry subscriber stations are assigned a channel sounding bandwidth greater than or equal to that of high-geometry stations, allowing them to sound the entire system bandwidth or a portion of it, using code division multiplexed signals to minimize interference and improve channel estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If cell-edge subscriber stations limit their channel sounding bandwidth to reduce interference, then inter-cell interference decreases, but system bandwidth requirements increase due to frequency hopping overhead
Solution Approach 1:
The system bandwidth is segmented into multiple channel sounding bandwidths (first channel sounding bandwidth and second channel sounding bandwidth). Cell-edge SSs are assigned a first channel sounding bandwidth that is less than the second channel sounding bandwidth assigned to non-cell-edge SSs. This segmentation allows cell-edge SSs to sound a portion of the system bandwidth, reducing interference while non-cell-edge SSs sound the entire bandwidth, eliminating the need for frequency hopping overhead.
2Object-affected harmful factors
If cell-edge subscriber stations use narrower bandwidth for channel sounding, then interference with neighboring cells is reduced, but channel estimation accuracy does not improve
Solution Approach 1:
Different channel sounding bandwidths are assigned based on the local characteristics of subscriber stations. Cell-edge SSs (experiencing high interference) are assigned a narrower first channel sounding bandwidth, while non-cell-edge SSs (experiencing low interference) are assigned a wider second channel sounding bandwidth. This local quality approach ensures that each SS uses the appropriate bandwidth for its specific location and interference conditions, optimizing both interference reduction and channel estimation accuracy.
3Reliability
If cell-edge subscriber stations transmit at higher power spectral density to improve signal strength, then received signal quality improves, but inter-cell interference increases
Solution Approach 1:
The system changes the bandwidth parameter for channel sounding transmissions based on SS location. Cell-edge SSs transmit channel sounding bursts over a narrower first channel sounding bandwidth, which allows them to maintain adequate signal strength while reducing the total interference power transmitted. This parameter change (bandwidth adjustment) directly addresses the trade-off between received signal quality and inter-cell interference for power-limited cell-edge stations.
Data Source
AI summary
A technique of operating a wireless communication system includes determining respective geometries of multiple subscriber stations, which include a first subscriber station and a second subscriber station, with respect to a serving base station. Respective channel sounding bandwidths for sounding the channel between the multiple subscriber stations and the serving base station are then scheduled, based on the respective geometries. The respective channel sounding bandwidths include a first channel sounding bandwidth (associated with the first subscriber station) and a second channel sounding bandwidth (associated with the second subscriber station). The first channel sounding bandwidth is greater than or equal to the second channel sounding bandwidth and the first subscriber station has a lower geometry than the second subscriber station.