Cognitive Radio Spectrum Handover Random Access Conflict Reduction
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Solution Overview
Problem
Current cognitive radio (CR) systems face significant random access conflicts during spectrum handover procedures, leading to higher failure probabilities and longer service interruptions, with no effective solution to manage these conflicts and differentiate user service levels.
Innovation Solution
Incorporating random access backoff time parameter information into the spectrum handover command, which includes a delay factor sequence specific to different service levels, allowing UEs to initiate random access procedures at predetermined times, thereby dispersing access and reducing conflicts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all UEs in connection state initiate random access procedure on target working frequency simultaneously during spectrum handover, then spectrum handover can be completed, but serious random access conflict occurs leading to higher failure probability and longer service interruption time
Solution Approach 1:
The base station performs preliminary actions by calculating and notifying each UE of its specific random access delay time before the actual random access procedure. This advance notification allows UEs to stagger their access attempts, preventing simultaneous conflicts while ensuring all UEs eventually complete handover. The delay time is determined based on UE identification information, creating a pre-planned access sequence that eliminates collision.
Solution Approach 2:
The random access procedure is segmented by introducing different delay times for different UEs. Instead of all UEs attempting access simultaneously, the access process is divided into multiple time slots based on UE identification. This segmentation of the access timeline distributes the random access attempts across different time periods, reducing conflict probability while maintaining handover completion for all UEs.
2Productivity
If all UEs initiate random access procedure simultaneously on target working frequency, then handover procedure can be executed, but random access conflict increases leading to higher failure probability
Solution Approach 1:
The base station calculates and notifies random access delay times to all UEs before they initiate their random access procedures. This preliminary timing arrangement ensures that UEs access the target frequency in a staggered manner rather than simultaneously, reducing collision probability and improving random access success rate while maintaining efficient handover execution.
Solution Approach 2:
The random access delay time is dynamically determined based on UE identification information. Each UE receives a specific delay time that is calculated by the base station, creating a dynamic access schedule that adapts to the number and identity of UEs performing handover. This dynamic timing mechanism optimizes access distribution without requiring complex collision resolution protocols.
3Device complexity
If no differentiation is made for users at different service levels, then simple handover procedure can be maintained, but user experience of CR system is influenced
Solution Approach 1:
Different quality of service is provided to different UEs through localized differentiation based on UE identification information. The base station calculates random access delay times specific to each UE's service level, allowing high-priority users to access the target frequency with shorter delays while low-priority users receive longer delays. This local quality differentiation within the handover procedure enhances user experience without requiring complete procedural redesign.
Solution Approach 2:
The random access delay time parameter is changed based on UE service levels. By modifying this single parameter according to UE identification information, the system achieves differentiated service treatment. High-priority UEs receive smaller delay values while low-priority UEs receive larger delay values, creating service level differentiation through parameter variation rather than procedural complexity.
Data Source
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AI summary
Various examples of the present disclosure describe a random access method and device in a CR system. The method includes: generating, by a base station device, a spectrum handover command, wherein the spectrum handover command comprises random access backoff time parameter information; and sending, by the base station device, the spectrum handover command to a user equipment in a cell to instruct the UE to initiate, during a spectrum handover procedure, a random access procedure using the random access backoff time parameter information. According to the various examples of the present disclosure, the random access backoff time parameter information is carried in the spectrum handover command, so that a random access conflict is suppressed during the spectrum handover procedure of the CR system. A large number of UEs that intensively perform random access on a target working frequency are pre-dispersed in time. As such, the delay and the failure probability of the random access on the target working frequency during the spectrum handover procedure are reduced, and thus the failure probability of the spectrum handover and the service interruption time are reduced, so that the user experience of the CR system is improved.