Dynamic Access Control for LTE Restricted Cells
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Solution Overview
Problem
In wireless communication systems, particularly in Evolved Universal Mobile Telecommunications Systems (E-UMTS) or Long Term Evolution (LTE), the presence of access-restricted cells, such as Closed Subscriber Group (CSG) cells, causes interference issues and degrades service quality when user equipment (UE) approaches these cells while camping on a typical cell, leading to interference and service degradation for both UE and network.
Innovation Solution
A method is introduced where the UE determines if a cell is access-restricted, checks the radio signal quality, and if it meets certain conditions, considers the cell accessible, allowing access even if previously restricted, thereby minimizing interference by evaluating downlink path loss values and using access indicators to enable access when conditions are met.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If access restriction is applied to CSG cells, then service quality for authorized users is improved, but interference to neighboring cells and service degradation for unauthorized users occurs
Solution Approach 1:
The patent changes the access control parameter from a static binary restriction to a dynamic condition-based restriction. The access indicator is modified from a fixed state to a variable state that depends on radio conditions (downlink path loss), allowing the system to adapt access rights based on actual network load and signal quality measurements.
Solution Approach 2:
The access restriction mechanism is transformed from a static configuration to a dynamic control system. The base station continuously monitors downlink path loss values and adjusts the access indicator accordingly, enabling real-time adaptation to changing network conditions and allowing flexible management of CSG cell access.
2Reliability
If strict access restriction is maintained, then authorized user service is protected, but UE camping on typical cells experiences service degradation when approaching restricted cells
Solution Approach 1:
The patent introduces a feedback mechanism where the UE measures downlink path loss values and reports this information to the base station. The base station uses this feedback to dynamically adjust the access indicator, creating a closed-loop control system that responds to actual radio conditions and ensures continuous service quality.
Solution Approach 2:
The access control parameter is changed from a fixed restriction to a dynamic state based on measured radio conditions. By monitoring downlink path loss and adjusting the access indicator accordingly, the system maintains service quality while allowing flexible access when network conditions permit.
3Device complexity
If access restriction is enforced without considering radio conditions, then network control is simplified, but uplink quality and communication link stability deteriorate
Solution Approach 1:
The patent introduces a new dynamic parameter (access indicator based on downlink path loss) to the access control mechanism. This additional parameter enables the system to consider radio conditions when making access decisions, thereby improving uplink quality and communication reliability while managing the added complexity through automated measurements and base station control.
Data Source
AI summary
Disclosed is the radio (wireless) communication system providing a radio communication service and the terminal, and more particularly, to a method of releasing a restricted-access based on a network's setting and an interference situation measured by the terminal in an Evolved Universal Mobile Telecommunications System (E-UMTS) evolved from the Universal Mobile Telecommunications System (UMTS) or a Long Term Evolution (LTE) system.