Backoff Domain Segmentation for Mobile Handover Collision Reduction
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Solution Overview
Problem
Current broadband wireless access systems, such as IEEE 802.16e, face challenges in supporting fast handover of subscriber stations between base stations due to high collision rates and inefficient resource allocation, leading to service disruptions and resource wastage during mobility.
Innovation Solution
Implementing a method that assigns backoff domains with specific start and end points based on priority levels for ranging operations, allowing subscriber stations to select and re-perform ranging operations within the most suitable backoff domain, thereby reducing collision rates and optimizing resource usage during handover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If subscriber stations perform ranging operations using a common access channel, then network access service is provided, but collision rates increase and resource allocation becomes inefficient
Solution Approach 1:
The common access channel is segmented into multiple backoff domains (first backoff domain and second backoff domain) with different priority levels. Subscriber stations select domains based on service type: handover ranging uses the first backoff domain for fast access, while initial ranging uses the second backoff domain. This segmentation reduces collisions by separating different access scenarios into dedicated time resources.
Solution Approach 2:
Different backoff domains are assigned different quality characteristics (priority levels) suited to specific access scenarios. The first backoff domain provides high-priority fast access for handover operations, while the second backoff domain provides standard access for initial ranging. This local quality differentiation ensures each access type receives appropriate resource allocation.
2Speed
If handover operations are prioritized for fast access, then service continuity is improved, but resource allocation efficiency decreases
Solution Approach 1:
The system dynamically allocates backoff domains based on the type of ranging operation performed. When a subscriber station performs handover ranging, it automatically selects the first backoff domain for fast access. When performing initial ranging, it selects the second backoff domain. This dynamic selection ensures handover operations receive prioritized resource allocation while maintaining overall system efficiency.
3Productivity
If multiple ranging operations share the same access channel, then channel utilization is improved, but service quality differentiation is lost
Solution Approach 1:
The access channel is divided into multiple backoff domains with different priority levels to maintain service quality differentiation. The first backoff domain is dedicated to handover operations requiring fast access, while the second backoff domain serves initial ranging operations. This segmentation allows the system to simultaneously achieve high channel utilization through shared access while preserving service quality differentiation through priority-based domain selection.
Data Source
AI summary
The present invention relates to a method for performing a ranging operation according to the priority order in a mobile communication system using a BWA (Broadcast Wireless Access) scheme. The method according to the invention for performing a range operation by a subscriber terminal in a mobile communication system using the BWA (Broadcast Wireless Access) scheme comprises steps of: receiving backoff domains having the start and end values of the backoff corresponding to each ranging operation, the backoff domains being determined from a base station according to the priority order of the ranging operations between the base station and subscriber terminals; performing a ranging operation and, if it is determined that the step of performing the ranging operation fails, selecting backoff domains among the received backoff domains according to the priority order of the performed ranging operations; and, re-performing the ranging operation according to the selected backoff domains.