LTE Base Station Scheduling for Wi-Fi Coexistence
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Solution Overview
Problem
The coexistence of LTE and Wi-Fi networks in the same frequency band leads to interference issues, causing Wi-Fi networks to spend a significant amount of time in listening mode, thereby degrading their performance, as LTE networks typically dominate the spectrum, reducing throughput and fairness in resource sharing.
Innovation Solution
A method where a cellular base station learns the operational characteristics of co-existing Wi-Fi networks, calculates a fair proportion of time for shared resource usage, and schedules LTE traffic to minimize interference by prioritizing uplink subframes for user equipment closer to the base station, allowing fair sharing of the frequency band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cellular base stations use scheduled OFDMA transmission in the same frequency band as Wi-Fi access points, then the capacity of the cellular base station is increased, but collision between cellular and Wi-Fi signals occurs
Solution Approach 1:
The frequency band is segmented into different time intervals, with the cellular base station transmitting during certain time slots and Wi-Fi access points transmitting during other time slots. This temporal segmentation allows both systems to share the same frequency band without signal collision, resolving the contradiction between increasing base station capacity and avoiding signal collision.
2Reliability
If Wi-Fi systems use CSMA carrier sense multiple access to reduce collisions, then collision avoidance is improved, but Wi-Fi networks spend excessive time in listening mode due to cellular interference
Solution Approach 1:
The cellular base station performs preliminary action by transmitting a notification signal before its scheduled transmission, informing Wi-Fi access points that the frequency band will be occupied. This allows Wi-Fi systems to avoid the listening mode delay and directly schedule their transmissions during available time slots, reducing the time lost to listening while maintaining collision avoidance.
3Length of stationary object
If cellular networks transmit at high power to ensure coverage, then transmission distance is improved, but interference with Wi-Fi networks increases
Solution Approach 1:
The transmission power is made local and variable rather than uniform. The cellular base station transmits at high power only during time slots when no Wi-Fi transmission is scheduled, and at reduced power during time slots when Wi-Fi access points are transmitting. This local differentiation of transmission quality resolves the contradiction between ensuring coverage and reducing interference.
Data Source
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AI summary
A method, computer program and base station are disclosed. The method is performed at a base station providing radio coverage within a cell of a cellular wireless communication network. The method comprises: prior to scheduling cellular traffic within a frequency band used by at least one access point located within the cell and supporting non-cellular wireless communication, determining an indication of operational characteristics of the at least one access point within the cell; assessing, based on a comparison of the determined operational characteristics of the at least one access point within the cell with operational characteristics of the base station providing the radio coverage within the cell, a proportion of time that the frequency band may be used by the base station; and scheduling transmission of the cellular traffic in the frequency band in accordance with the assessed proportion of time. Aspects and embodiments may provide a configurable fair method according which the mode of operation of a scheduled cellular system can be intelligently chosen to cause a predictable degree of disruption to a contention-based system which shares resource with the scheduled cellular system.