Research Plan on Scheduling Algorithms for WDM-PON under SUCCESS-HPON Architecture

• To provide better fairness among all traffic flows both up- and downstream, we need more systematic approach in designing scheduling algorithms, hopefully based on some quantitative analysis like fairness bounds. For systematic approach and quantitative analysis, it's critical to extend the definition of fairness to multiple-server case.
• Deficit Round-Robin (DRR) fair queueing and its many variations could be good starting points in that they could naturally support variable size packets and rather simple to implement.

Barack Obama, Illinois's Senator, writes on Lincoln

The writing of a man is himself. In this regard, his short article on
The President Lincoln in the recent special issue of Time Magazine
reveals much of himself; I am interested in him, at least.

Politics and Politicians, especially nowadays, are definitely not my favorite topics; I'm simply disappointed at all and have been
thinking that it would be hard to see again figures like Lincoln and
Reagan. Barack's writing, however, reminds me that there are still
God's chosen men and wemen here and there, even right now.

OMNeT++: The Best Open Source Network Simulator!

I have been using it for various kinds of optical networking simulations since 2001; in my humble opinion, this is simply the best open source networking simulator available now in terms of speed, flexibility and extensibility. The only other simulator that comes close to it is OPNET, which is, however, a commercial one and very expensive.

For more information, please visit its home page, where you could find all the relevant projects and publications.

My Recent Paper on Scheduler Design and Analysis for WDM-PON under SUCCESS-HPON Architecture

Kyeong Soo Kim, David Gutierrez, Fu-Tai An, and Leonid G. Kazovsky,
"Design and performance analysis of scheduling algorithms for WDM-PON under SUCCESS-HPON architecture,"
To appear in IEEE/OSA Journal of Lightwave Technology, Nov. 2005.

Abstract

We report the results of our design and performance analysis of two new algorithms for efficient and fair scheduling of variable-length frames in a wavelength division multiplexing (WDM)-passive optical network (PON) under Stanford University aCCESS-Hybrid PON (SUCCESS-HPON) architecture. The WDM-PON under the SUCCESS-HPON architecture has unique features that have direct impacts on the design of scheduling algorithms: First, an optical line terminal (OLT) uses tunable transmitters and receivers that are shared by all the optical network units (ONUs) served by the OLT to reduce the number of expensive dense WDM (DWDM) transceivers. Second, also for cost reduction, ONUs have no local DWDM light sources but use optical modulators to modulate optical continuous wave (CW) bursts provided by the OLT for upstream transmissions. Therefore, the tunable transmitters at the OLT are used for both upstream and downstream transmissions. To provide efficient bidirectional communications between the OLT and the ONUs and guarantee fairness between upstream and downstream traffic, we have designed two scheduling algorithms – batching earliest departure first (BEDF) and sequential scheduling with schedule-time framing (S3F). The BEDF is based on the batch scheduling mode where frames arriving at the OLT during a batch period are stored in virtual output queues (VOQs) and scheduled at the end of the batch period. It improves transmission efficiency by selecting the frame with the earliest departure time from a batch of multiple frames, which optimizes the usage of tunable transmitters in scheduling. Considering the high complexity of the optimization process in BEDF, we have also designed the S3F based on the sequential scheduling mode as in the original sequential scheduling algorithm proposed earlier. In S3F we use VOQs to provide memory space protection among traffic flows and a granting scheme together with schedule-time framing for both upstream and downstream traffic to reduce framing and guard band overhead. Through extensive simulations under various configurations of the tunable transmitters and receivers, we have demonstrated that both the BEDF and S3F substantially improve the throughput and delay performances over the original sequential scheduling algorithm, while guaranteeing better fairness between upstream and downstream traffic.

Index Terms

• Access
• Media access control (MAC) protocols
• Passive optical network (PON)
• Scheduling
• Wavelength division multiplexing (WDM)

Vitreous Floaters

This is also called 'eye floaters', 'vitreous opacities', or '비문증' in Korean.

Here is the link for more detailed information:
http://www.eyefloaters.com/

I've finally got my Gmail account!

Finally got my Gmail account!
Here is the address: kyeongsooDotKimAtGmailDotCom