Group meeting

Topic: "Interference Model in Wireless Networks"
A survey of the interference models in wireless networks. Hope it can be a starting point if anyone wants to study or use interference model. The powerpoint is in the public/group_meeting folder.

Topic: "SNR Walls for Signal Detection", Rahul Tandra and Anant Sahai, IEEE JOURNAL OF SELECTED TOPICS IN SIGNAL PROCESSING, VOL. 2, NO. 1, FEBRUARY 2008
presentation:
SNRwalls.ppt
paper:
SNRwlsfsidet.pdf

Topic: "A Distributed Optimization Algorithm for Cognitive Radio Networks", Yi Shi, T. Hou, Vtech INFOCOM 2008
The paper, technical report, and presentation can be found in /home/public/group_meeting/eric/2008_04_07\

Topic: "Better Wi-Fi Experience: a user's perspective"
In the meeting, we've discussed three papers about AP selection, AP aggregation and Wi-Fi interface power saving. The discussed paper and slides can be found in directory /home/public/group_meeting/public/group_meeting

Topic: "Optimal Transmission Strategy for OSA"
The discussed paper can be found in directory /home/public/group_meeting/senhua/mar_03_2008.

(Dan Xu?)

We talked about my ongoing research on integrated WiFi/WiMAX networks. The ppt can be found in /home/public/group_meeting/

Topic: "The road to the success of Ph.D"
Discussed important factors for the success of Ph.D in CS and ECE. Some slides and materials can be found in the server directories /home/public/group_meeting and /home/public/phdroad. The discussion is very helpful.

Topic: "Style of technical writing"
Slides can be found in the server directory /home/public/group_meeting

Topic: "Non-intrusive opportunistic spectrum access in cognitive radio networks"
Cognitive radio is a promising technique to relieve the imbalance between spectrum shortage and wasteful spectrum usage in the allocated bands. It enables secondary users to have opportunistic access to the spectrum vacated by the primary user and thus increases the spectrum efficiency. In cognitive radio networks, the protection of the primary user's communication is vital to the success of opportunistic spectrum access. We focus on the non-intrusive spectrum access schemes. Specifically, we have defined several protection metrics (e.g., busy time collision probability, overlapping time, packet collision probability, interference power) to quantify the harm to the primary user, and designed the spectrum access schemes for the secondary users via a constraint optimization approach. Several spectrum access schemes are proposed and analyzed. We have shown that, the characteristics of primary user's behavior (constraints, idle time distribution, location etc.) have significant impacts on the performance of the secondary user. We also shown that, the availability of knowledge about the primary user's behavior is also important to the throughput performance of the secondary user.

Topic: "Study of Public Safety Spectrum in Howard County, Maryland"
In a joint study with JHU/APL, we have been studying activity in the public safety spectrum in Howard County, Maryland. The Howard County public safety system consists of 23 narrow voice-only channels interspersed throughout the 850-870 Mhz band. The entire 800 Mhz band is considered a prime candidate to be used in opportunistic spectrum access schemes because of its strong physical properties and relatively low activity. Our investigation of these 23 channels has revealed many issues that arise in power detection schemes in real-life scenarios: how to choose a power threshold which can eliminate false detections, and how we process the activity statistics to obtain "ground truth" detection of primary users' activity. Since our initial paper (DySPAN 2007), we have also expanded the study to look at the entire 20 Mhz band to determine statistics on bandwidth availability, as well as characterize the 23 channels activity probabilistically.

Topic: "Non-intrusive cognitive radio networks based on smart antenna technology"
Abstract: We will discuss our paper accepted by IEEE GLOBECOM 2007. We proposed a system scheme to exploit the spectrum opportunities in the spatial dimension by deploying multiple antennas at cognitive transmitter, and showed that the proposed scheme can improve the spectrum efficiency considerably.

Paper is available here PID467562.pdf

Topic: "Spectrum Auctioneering"

Abstract: We will discuss the best student paper from DySPAN 07, "A General Framework foor Wireless Spectrum Auctions".

Haitao Zheng's group at UCSB CS department has done extensive research on spectrum assignment in the opportunistic spectrum setting. They have previously addressed the complexity of the optimal spectrum allocation problem, with considerations made for fairness. This paper builds upon those results, providing a "framework" for spectrum auctions in an open spectrum context, addressing the problems of fairness between customers as well as the needs of sellers ($$). The paper introduces a "bidding language" which allows sellers and buyers to express their desired parameters. For reference on their use of graph theory in the optimal spectrum problem, read:

"Utilization and Fairness in Spectrum Assignment for Opportunistic Spectrum Access".

Comment: interesting idea on how to reduce LP complexity by imposing simple more restrictive leftmost-node constraint. Worth a try on similar problems.

Topic: SCAN: Spectrum Allocation in Cognitive Wireless Mesh Network

Abstract: This talk would introduce an ongoing research project SCAN. The main idea is how to better ultilize some propoerties of cognitive radio for wireless mesh network. To this end, we first propose a centralized static spectrum allocation strategy with consideration of characteristics of "white space". In addition, a traffic adpative scheme would also be presented to combat some pros of static scheme. For slides, you may find it in /home/public/group_meeting

Topic: Opportunistic spectrum access of in cognitive radio networks

Abstract: I will talk about the analytical and simulation results on the achievable throughput of secondary user under the collision probability constraint posed by the primary user. I uploaded the draft submitted to INFOCOM2008 in /home/public/group_meeting/senhua/aug_02_2007. The ppt slice is available in the server in the same directory as the draft paper.

Topic: Network coding and aggregation in wireless networks

Abstract: I am gonna talk about the idea on combining network coding with aggregation in wireless networks. Some preliminary results validate our motivation. You can find the ppt in /home/public/group_meeting