Schedule of Talks: Fall 2012

    Past Talks:

  • Date: 11-30-2012
    Speaker: Aditya Sundarrajan
    Talk Title:XIA: Efficient Support for Evolvable Internetworking

  • Date: 11-16-2012
    Speaker: Hanif Rahbari
    Talk Title:Temporal Reachability Graphs

  • Date: 11-02-2012
    Speaker: Mohammad Jamal Abdel Rahman
    Talk Title: Adaptive Frequency Hopping Algorithms for Multicast Rendezvous in DSA Networks
    Establishing communications in a dynamic spectrum access (DSA) network requires communicating nodes to “rendezvous” before transmitting their data packets. Frequency hopping (FH) provides an effective method for rendezvousing without relying on a predetermined control channel. FH rendezvous protocols have mainly targeted pairwise rendezvous, using fixed (non-adaptive) FH sequences and assuming a homogeneous spectrum environment, i.e., all nodes perceive the same spectrum opportunities. In this paper, we address these limitations by developing three multicast rendezvous algorithms: AMQFH, CMQFH, and nested-CMQFH. The three algorithms are intended for asynchronous spectrum-heterogeneous DSA networks. They provide different tradeoffs between speed and robustness to node compromise. We use the uniform k-arbiter and the Chinese remainder theorem (CRT) quorum systems to design our multicast rendezvous algorithms. We also design two “optimal” channel ordering mechanisms for channel sensing and assignment, one for AMQFH and the other for CMQFH and nested-CMQFH. Finally, we develop a proactive out-of-band sensing based dynamic FH (DFH) algorithm for online adaptation of the FH sequences used in the proposed rendezvous algorithms. Extensive simulations are used to evaluate our algorithms.

  • Date: 10-26-2012
    Speaker: Junseok Kim
    Talk Title: 802.11ec: Collision Avoidance without Control Messages

  • Date: 10-19-2012
    Speaker: Selda Uyanıkr
    Talk Title: AutoMAC: Rateless Wireless Concurrent Medium Access

  • Date: 10-12-2012
    Speaker: Harish Kumar Shankar
    Talk Title: Cooperative QoS-aware Sensing/Probing Architecture and Cross-layer Protocol Design for Multi-rate CRNs
    The intermittent nature of spectrum availability combined with the uncertainty in the channel quality makes the problem of supporting multimedia communications over the TV white spaces very challenging. In this paper, we design a QoS-aware cooperative sensing/probing architecture called QC-SPA and a cross-layer protocol, which encompasses all the essential components to efficiently support bandwidth-hungry multimedia applications. In addition to supporting multimedia flows, the proposed architecture also accommodates low-bandwidth traffic flows. Our design consists of five principal components. First, we estimate the channel usage patterns of incumbent users and use these patterns to schedule the spectrum sensing/probing process and to compute the most optimal channel for disseminating control and management information. Second, we propose an adaptive TDMA-based frame structure whose objective is to minimize the control message overhead and hence maximize the data-transmission period. Third, we propose a novel multi-channel multi-user concurrent sensing/probing scheme, which exploits the inherent multi-user diversity of the wireless system and maximizes the discovered opportunities over a given time period. Fourth, from the outcome of the channel sensing/probing process, we design a centralized data-channel allocation scheme that aims at maximizing the number admitted flows. Finally, we propose an adaptive double-threshold based spectrum sensing algorithm that minimizes the false-alarm probability in addition to guaranteeing a given degree of protection to incumbent users. This sensing algorithm is shown to increase spectrum discovery per unit time when compared with traditional fixed single-threshold based sensing algorithms. Performance evaluation results bolster the efficiency of the proposed schemes.

  • Date: 10-05-2012
    Speaker: Yan Zhang
    Talk Title: Watchdogs to the rescue: Securing wireless TCP

  • Date: 09-28-2012
    Speaker: Wessam Afifi
    Talk Title: Improving Spectrum Efficiency using Micro-ACKs

  • Date: 09-14-2012
    Speaker: Alejandro Proaño
    Talk Title: Physical Layer Security in Wireless Networks

  • Date: 09-07-2012
    Speaker: Diep Nguyen
    Talk Title: Embrace Multi-antenna Techniques to Sensor and Cognitive Networks

  • Date: 08-31-2012
    Speaker: Hanif Rahbari
    Talk Title: Packet Detection and Recovery Techniques

  • Networking Seminar Fall 2013

    Networking Seminar Spring 2013