1. Solve Frequent Handover Requirement
Month Year
Jul 2005
November 2005
Solve Frequent Handover Requirement
Date:
Authors:
Notice: This document has been prepared to assist IEEE It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE
Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures < ieee802.org/guides/bylaws/sb-bylaws.pdf>, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE Working Group. If you have questions, contact the IEEE Patent Committee Administrator at
Bin Wang, ZTE Corporation
Bin Wang, ZTE Corporation

2. Month Year
Jul 2005
November 2005
Abstract
This document suggests the requirement to solve frequent handover of STAs in ESS for Wireless Network Management.
Bin Wang, ZTE Corporation
Bin Wang, ZTE Corporation

3. Agenda Introduction Frequent handover illustration
Month Year
Jul 2005
November 2005
Agenda
Introduction
Frequent handover illustration
The harm of frequent handover
Current of commercial equipment
Proposed text
Bin Wang, ZTE Corporation
Bin Wang, ZTE Corporation

4. Introduction The meaning of frequent handover:
Month Year
Jul 2005
November 2005
Introduction
The meaning of frequent handover:
Because of the movement of STA or the change of wireless circumstance and network condition, STAs in the overlapped range of two or more APs will handover from one to another and check back just after a little while.
In a fixed period, STA may in this kind of “check out and check back” status continuously;
So called “Ping-Pang” effect.
Bin Wang, ZTE Corporation
Bin Wang, ZTE Corporation

5. Frequent handover illustration
November 2005
Frequent handover illustration
Bin Wang, ZTE Corporation

6. Frequent handover illustration
November 2005
Frequent handover illustration
Bin Wang, ZTE Corporation

7. The harm of frequent handover
November 2005
The harm of frequent handover
Most part of frequent handover is unnecessarily
STA decided to handover just because of the signal strength.
Sometimes, The service STA can acquire from APs involved in frequent handover has no substantively difference, or unluckily, becoming worse.
High risk of application interrupt
The time consumed during once handover will up to 100ms even with the 80211r help, it is unacceptable for some time urgent application. (e.g. VoWLAN)
The 2-layer router information must updated as soon as possible to keep the application continuous.
Bin Wang, ZTE Corporation

8. The harm of frequent handover 2
November 2005
The harm of frequent handover 2
Increase the AP’s management overhead
The APs involved in frequent handover must management the whole process of STA’s movement, including disassociation, deauthentication, authentication, association……
Deteriorate the radio environment
The AP’s resources will be wasted on this kind of unnecessarily handover.
Disarrange the load balancing schedule
Maybe the STA moved to the direction inconsistent to the AP’s load balancing status.
Bin Wang, ZTE Corporation

9. Current of commercial equipment
Month Year
Jul 2005
November 2005
Current of commercial equipment
Use window protocol to control frequent handover.
Only when the target AP’s signal is higher than that of current AP’s over the threshold can the STA initiate a DISASSOCATION.
Advantages:
Signal strength means link quality.
Can eliminate the arbitrariness in a degree.
Disadvantages:
Signal strength doesn't means STA can acquire equivalent service in new AP.
The value of threshold is hard to select.
Can not ensure efficiency.
May cause confusions in roaming.
Load balancing can not completely eliminate frequent handover.
Current load balancing mechanism can lead to frequent handover sometimes.
Bin Wang, ZTE Corporation
Bin Wang, ZTE Corporation

10. November 2005
Proposed text
TGv should consider to solve the problem of frequent handover in wireless network management, supply detect/avoid/control mechanism.
TGv should take the following factors into account when solve frequent handover:
Signal strength
Single direction channel caused by AP’s different emission power from different vendors or different model.
Network resources or load information
Bin Wang, ZTE Corporation

11. November 2005
Feedback?
Bin Wang, ZTE Corporation