1. ESS Load Balancing Requirements
Month Year
Jul 2005
July 2005
ESS Load Balancing Requirements
Date:
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Bin Wang, ZTE Corporation
Bin Wang, ZTE Corporation

2. Month Year
Jul 2005
July 2005
Abstract
This document suggests ESS load balancing requirements for Wireless Network Managements.
Bin Wang, ZTE Corporation
Bin Wang, ZTE Corporation

3. Agenda Introduction Load balancing illustration 802.11 Current
Month Year
Jul 2005
July 2005
Agenda
Introduction
Load balancing illustration
Current
Load balancing in ESS
Proposed text
Bin Wang, ZTE Corporation
Bin Wang, ZTE Corporation

4. Introduction The meaning of load balancing:
Month Year
Jul 2005
July 2005
Introduction
The meaning of load balancing:
The traffic in ESS maintain even distribution during it’s life, varies smoothly.
It is reasonable to satisfy high QoS requirement Applications that some STAs with low-level QoS requirements will be handed over to another AP, release their resources for the high QoS application.
The necessity of load balancing:
The utilization of the ESS’s resources will be more evenly and effectively, could decrease drastic wave and boosting of traffic.
The characteristics of ESS: BSSs live in harmony with each other to form a ESS, and work together to supply services for STAs in the ESS.
To guarantee the continuity of the Application which has QoS requirements.
To prevent the happening of AP’s congestion and choke.
Bin Wang, ZTE Corporation
Bin Wang, ZTE Corporation

5. Unbalanced Wireless Network
July 2005
Unbalanced Wireless Network
Bin Wang, ZTE Corporation

6. July 2005
AP Load Balancing
Bin Wang, ZTE Corporation

7. Month Year
Jul 2005
July 2005
Current
The APs in ESS manage their own load status respectively and independently, and the distribution of load burden among APs just according to RSSI.
STA based hand over: After STA decide to handover, it break it’s current connection and then subscribe JOIN request to it’s favorite target;
As current hand over is a new process of authentication and JOIN, it is in all probability to happen that STA frequently checking out from a AP and checking in back to the same one, which degrades the performance of ESS tremendously.
Handover caused by load balancing is a “two-edged sword”. It could release the burden of AP or break the application of STA. So the action must be controlled and restricted.
Advantages:
STA knows exactly the occasion of hand over.
STA knows exactly the strength of signals in around.
Disadvantages:
No communication and correspond among BSSs.
The information STA can acquire is insufficient to make correct decision.
Huge differences between STAs from different venders.
Uncontrolled handover.
Heavy bss will retain their chaos, while the lighter couldn’t be a partaker.
Bin Wang, ZTE Corporation
Bin Wang, ZTE Corporation

8. July 2005
Load balancing in ESS
When unbalancing happening, two methods can the network be operate:
Load limitation: when new STA JOIN, check load status and reject.
Let some STAs who has adequate condition to handover to light APs.
An AP has more confederates to accomplish one task.
Solve the same problem with more sufficient resources.
Bin Wang, ZTE Corporation

9. AP based or AP-STA collaborated load balancing
July 2005
AP based or AP-STA collaborated load balancing
ESS has the inherent privilege to gather global load balancing information.
Could make use of both the network condition and the client status.
Could make the decision more accurate.
Could make the command or recommend generated by load balancing policy more meaningful.
Diminish the “bad” handover or “regret” handover.
Bin Wang, ZTE Corporation

10. July 2005
Proposed text
TGv should support ESS Load balancing to improve throughput, and enlarge the network tolerance, ultimately to improve network performance.
AP based or AP-STA collaborated load balancing policy is reasonable.
Bin Wang, ZTE Corporation

11. July 2005
Feedback?
Bin Wang, ZTE Corporation