Fast Ranging Message Transmission During Handover
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Solution Overview
Problem
In portable Internet systems based on the IEEE 802.16e standard, handover delays occur due to delayed handover initiation, lost control messages, and inefficient allocation of wireless resources during the fast ranging process, leading to wasted resources and prolonged ranging operations.
Innovation Solution
A method that recalculates the action time for transmitting fast ranging information messages based on the time of handover confirmation and RAS switching time, ensuring timely delivery of fast ranging information even when handover decisions are delayed or control messages are lost, thereby reducing standby times and resource wastage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If handover initiation is delayed or control messages are lost during handover decision operation, then handover delay occurs and fast ranging IE cannot be received, but the mobile station still needs to perform handover to maintain service continuity
Solution Approach 1:
The target RAS pre-calculates and stores the fast ranging IE message in advance before the mobile station arrives. When the mobile station performs handover, the pre-prepared message can be immediately transmitted without waiting for message exchange delays, thus resolving the contradiction between service continuity reliability and handover delay
Solution Approach 2:
The patent introduces an intermediary mechanism where the target RAS proactively transmits the fast ranging IE message to the mobile station during the handover process, rather than waiting for the mobile station to request it. This intermediary action ensures the message is delivered even when handover initiation is delayed or control messages are lost
2Ease of manufacture
If fast ranging IE is allocated to action time during handover decision operation, then wireless resource allocation is simplified, but resources are wasted when handover is cancelled due to good signal state
Solution Approach 1:
The patent makes the fast ranging IE transmission dynamic by conditionally transmitting the message based on whether handover is actually performed. The target RAS transmits the pre-calculated message only when handover occurs, adapting the resource allocation to actual handover needs rather than allocating unconditionally, thus reducing wireless resource wastage while maintaining allocation simplicity
3Speed
If mobile station waits for fast ranging IE at action time, then ranging operation can be fast when message is received, but standby time increases when message is not received due to delayed handover
Solution Approach 1:
The target RAS performs preliminary calculation and preparation of the fast ranging IE message in advance, storing it ready for transmission. This preliminary action ensures that when the mobile station arrives, the message is already prepared and can be transmitted immediately, eliminating the standby time while maintaining fast ranging speed
Data Source
AI summary
Disclosed is a portable internet system, and more particularly, to a method of supporting fast ranging upon handover. The method comprises calculating an action time based on a time when a handover confirmation message is received from a serving Radio Access Station (RAS), in a target RAS; and transmitting a fast ranging information message to a mobile station on the basis of the action time.