Affan Syed - Academia.edu (original) (raw)

Papers by Affan Syed

Unrestricted An understanding of the key areas of difference in acoustic underwater sensor networ... more Unrestricted An understanding of the key areas of difference in acoustic underwater sensor networks and their impact on network design is essential for a rapid deployment of aquatic sensornets. Such an understanding will allow system designers to harvest the vast literature of research present in RF sensornets and focus on just those key aspects that are different for acoustic sensornets. Most complexities at the physical layer will eventually be handled either by assuming short ranges or with technology advancements making complex algorithms both cost and power efficient. However, the impact of large latency and the resulting magnification of multipath will remain a great impediment for developing robust sensor networks. This thesis contributes towards an understanding of, and solutions to, the impact of latency on sensornet migration to an underwater acoustic environment.; The thesis of this dissertation is that Latency-awareness allows both migration of existing terrestrial senso...

Proceedings IEEE INFOCOM 2006. 25TH IEEE International Conference on Computer Communications, 2006

Distributed time synchronization is an important part of a sensor network where sensing and actua... more Distributed time synchronization is an important part of a sensor network where sensing and actuation must be coordinated across multiple nodes. Several time synchronization protocol that maximize accuracy and energy conservation have been developed, including FTSP, TPSN, and RBS. All of these assume nearly instantaneous wireless communication between sensor nodes; each of them work well in today's RF-based sensor networks. We are just beginning to explore underwater sensor networks where communication is primarily via acoustic telemetry. With acoustic communication, where the propagation speed is nearly five orders of magnitude slower than RF, assumptions about rapid communication are incorrect and new approaches to time synchronization are required. We present Time Synchronization for High Latency (TSHL), designed assuming such high latency propagation. We show through analysis and simulation that it achieves precise time synchronization with minimal energy cost. Although at very short distances existing protocols are adequate, TSHL shows twice the accuracy at 500m, demonstrating the need to model both clock skew and propagation latency.

IEEE Wireless Communications and Networking Conference, 2006. WCNC 2006., 2006

This paper explores applications and challenges for underwater sensor networks. We highlight pote... more This paper explores applications and challenges for underwater sensor networks. We highlight potential applications to offshore oilfields for seismic monitoring, equipment monitoring, and underwater robotics. We identify research directions in shortrange acoustic communications, MAC, time synchronization, and localization protocols for high-latency acoustic networks, longduration network sleeping, and application-level data scheduling. We describe our preliminary design on short-range acoustic communication hardware, and summarize results of high-latency time synchronization.

2015 IEEE International Conference on Communications (ICC), 2015

Infected machines pose threats to not only their users, but also their network owners (ISPs and e... more Infected machines pose threats to not only their users, but also their network owners (ISPs and enterprises). To neutralize the effect of these infected machines, common solutions span two ends of an architectural spectrum; either fully distributed solutions that are host-based, or completely centralized appliances at the network core. We present NetworkRadar, inspired by an SDN-enabled ISP framework, that operates in between these extremes and contains the benefits of both these approaches. We perform data-plane intensive event monitoring at aggregation points close to customers, and maintain a centralized control plane for correlating and high-granularity blocking of malicious bot activity. Here we present the architecture of our solution and evaluate a prototype deployment over an isolated slice of an ISP network, showing its viability due to a negligible (<;1%) impact on customer throughput and its control plane scaling linearly to the customer base.

Proceedings of the 2015 ACM Sixth International Conference on Future Energy Systems - e-Energy '15, 2015

This paper targets the unexplored problem of demand response within the context of power-grids th... more This paper targets the unexplored problem of demand response within the context of power-grids that are allowed to regularly enforce blackouts as a mean to balance supply with demand: highly-stressed grids. Currently these utilities use as a cyclic and binary (power/no-power) schedule over consumer groups leading to significant wastage of capacity and long hours of no-power. We present here a novel building DLC system, Aashiyana, that can enforce several user-defined low-power states. We evaluate distributed and centralized load-shedding schemes using Aashiyana that can, compared to current load-shedding strategy, reduce the number of homes with no power by > 80% for minor change in the fraction of homes with full-power.

This paper aims to improve the accuracy of port-scan detectors by analyzing traffic of BitTorrent... more This paper aims to improve the accuracy of port-scan detectors by analyzing traffic of BitTorrent hosts and differentiating their respective BitTorrent connection (attempts) from port-scans. It is shown that by looking at BitTorrent coordination traffic and modelling port-scanning behavior the number of BitTorrent-related false positives can be reduced by 80% without any loss of IDS accuracy.

2014 44th Annual IEEE/IFIP International Conference on Dependable Systems and Networks, 2014

ABSTRACT Botnets are an evolutionary form of malware, unique in requiring network connectivity fo... more ABSTRACT Botnets are an evolutionary form of malware, unique in requiring network connectivity for herding by a botmaster that allows coordinated attacks as well as dynamic evasion from detection. Thus, the most interesting features of a bot relate to its rapidly evolving network behavior. The few academic and commercial malware observation systems that exist, however, are either proprietary or have large cost and management overhead. Moreover, the network behavior of bots changes considerably under different operational contexts. We first identify these various contexts that can impact its fingerprint. We then present Titan: a system that generates faithful network fingerprints by recreating all these contexts and stressing the bot with different network settings and host interactions. This effort includes a semi-automated and tunable containment policy to prevent bot proliferation. Most importantly, Titan has low cost overhead as a minimal setup requires just two machines, while the provision of a user-friendly web interface reduces the setup and management overhead.

Proceedings of the 6th ACM conference on Embedded network sensor systems - SenSys '08, 2008

38th Annual IEEE Conference on Local Computer Networks, 2013

ABSTRACT Software-defined networking (SDN) is envisioned to provide a centralized interface to pr... more ABSTRACT Software-defined networking (SDN) is envisioned to provide a centralized interface to programmatically manage networking elements. However, despite its conceptual simplicity, current switch and SDN architectures have poor performance with little support to innovate and test novel SDN applications. We propose an application extensibility framework that allows researchers to build new SDN applications without requiring modification to the OpenFlow-based plumbing available today. We also employ both hardware and software packet processing capabilities of switching elements by offloading intensive per-packet processing onto the switch processing pipeline using dynamically loadable packet processing modules (PPMs). Our architecture thus allows flexibility in the type of applications alongside high switching performance. We believe that our architecture will unleash the potential of SDN by inspiring the SDN “killer app”. We evaluate our framework using an encryption middlebox application and show a two orders-of-magnitude improvement over an implementation using the current SDN architecture when using hardware offload blocks.

Proceedings of the Seventh ACM International Conference on Underwater Networks and Systems - WUWNet '12, 2012

Underwater acoustic sensor networks (UWSN) is a relatively new research area, and remains quite c... more Underwater acoustic sensor networks (UWSN) is a relatively new research area, and remains quite challenging due to limited bandwidth, low data rate, severe multipath, and high variability in the channel conditions. These complicated and non-linear channel characteristics render incorrect most simplifying assumptions used in simulations. We believe that, while researchers have proposed several novel protocols, their use of models and simulations as the only form of validation and intra-protocol comparison remains removed from reality. We argue that research experimentation is hindered by two fundamental constraints: high cost of underwater networking experiments, and lack of a single, easily-replicable platform for evaluation. We present here Underwater Platform to Promote Experimental Research (UPPER): a low-cost (about 25/node)andflexibleunderwaterplatformdesignedtoenablecost−e↵ectiveandrepeatableexperimentation.WeutilizeCOTScomponentstoprovideaHW/SWintegratedsolutionthatinterfacesourcustomhydrophones(25/node) and flexible underwater platform designed to enable cost-e↵ective and repeatable experimentation. We utilize COTS components to provide a HW/SW integrated solution that interfaces our custom hydrophones (25/node)andflexibleunderwaterplatformdesignedtoenablecost−e↵ectiveandrepeatableexperimentation.WeutilizeCOTScomponentstoprovideaHW/SWintegratedsolutionthatinterfacesourcustomhydrophones(5 ea.) with laptops that act as an SDR-based physical layer, while allowing higher layer protocols to interact via a plug-and-play interface. We show that our platform can communicate over small (5-10m) distances and over a range of data rates (100-600bps). We believe our platform removes the barrier to validating simulation results in underwater environments and also allowing a fair comparison with related protocols.

Lecture Notes in Computer Science, 2015

We propose a Corrupt Packet Recycling (CPR) approach for WSN that processes and forwards partiall... more We propose a Corrupt Packet Recycling (CPR) approach for WSN that processes and forwards partially-corrupt packets over multiple hops without necessitating their complete recovery. We motivate this approach with two insights: address-agnostic routing in WSN can forgive header errors since intermediate nodes know the next hop and the destination; and that payload errors can be either interpolated, due to error-tolerant nature of information in WSN applications, or rectified using spatio-temporal redundancies. CPR, without introducing any transmission overhead, improves information delivery rate by up to 4×.

Proceedings of the 3rd International ICSTConference on Wireless Internet, 2007

We consider the end-to-end fair rate control problem in a multi-hop Aloha network with capture. C... more We consider the end-to-end fair rate control problem in a multi-hop Aloha network with capture. Capture (also referred to as co-channel interference tolerance) occurs when a packet with a stronger signal strength can be correctly decoded at the receiver despite the presence of a weaker interfering signal. We provide an approximate model for the link capacity with capture and incorporate it into a cross-layer joint link/session rate optimization framework. We show that this is a convex optimization problem and then present a sub-gradient algorithm for realistic distributed implementation in a network. Through analysis and simulations, we quantify the improvement in performance obtained with capture. We find that the capture effect benefits primarily low-contention links and non-bottleneck sessions. As a result, although capture provides significant improvements in the total throughput (sum rate), it seems to provide little improvement in the objective function (sum of the logarithm of the rates).

Proceedings of the second workshop on Underwater networks - WuWNet '07, 2007

The goal of this paper is to gain deep understanding of how location-dependent propagation latenc... more The goal of this paper is to gain deep understanding of how location-dependent propagation latency affects medium access control (MAC) by using ALOHA as a case study. MAC protocols in underwater acoustic networks suffer from latency that is five orders-of-magnitude larger than that in radio networks. Existing work on analyzing MAC throughput in RF networks, where the propagation latency is negligible, generally makes assumptions that render propagation latency irrelevant. As a result, only transmit time is considered as being uncertain in contention-based protocols. We introduce the spatial dimension of uncertainty that is inherent to varying locations of transmitters, resulting in unequal propagation latency to a receiver, where collision occurs. We show through simulation that the benefit of synchronization in slotted ALOHA is lost due to such latency. We propose a modification that adds guard bands to transmission slots to handle spatial uncertainty. We then perform simulation and first order analysis on this modified MAC to find its optimal operating parameters.

Proceedings of the 8th ACM Conference on Embedded Networked Sensor Systems - SenSys '10, 2010

In many cases, sensornets require continuous monitoring, 24x7, at remote, inaccessible locations ... more In many cases, sensornets require continuous monitoring, 24x7, at remote, inaccessible locations making energy management a critical part of most sensornets. The sensornet research community has explored energy conservation and energy harvesting to address this problem of long-lived sensornets. Energy conservation is a primary concern in almost all sensornet work, and techniques from low-power hardware and OSes to coordinated network protocols and applications. Complementing energy conservation, energy harvesting gathers new energy from the environment.

Proceedings of the Fifth ACM International Workshop on UnderWater Networks - WUWNet '10, 2010

The key aspect in the design of any contention-based medium access control (MAC) protocol is the ... more The key aspect in the design of any contention-based medium access control (MAC) protocol is the mechanism to measure and resolve simultaneous contention. Generally, terrestrial wireless MACs can only observe success or collision of a contention attempt through carrier sense. An implicit estimate of the number of contenders occurs through repeated observation and changing back-o contention window. Recent work in underwater MAC protocols suggest there it is possible to directly count the number of contenders by exploiting the spatio-temporal uncertainty inherent to high-latency underwater acoustic medium. Prior work has shown how to use counting in underwater MACs, and how to optimize contention windows in radio MACs. In this paper, we quantify bounds to convergence time for MAC protocols employing exact contender counting. We show that perfect counting allows contention to converge quickly, independent of network density, with an asymptotic limit of 3.6 contention rounds on average. We conrm this analysis with simulation of a specic underwater MAC protocol, and suggest the opportunity for the results to generalize for any radio-based MACs that estimate contenders.

Proceedings of the 9th ACM Conference on Embedded Networked Sensor Systems - SenSys '11, 2011

Proceedings of the 5th international conference on Future energy systems - e-Energy '14, 2014

We propose to demonstrate a smart-home solution coupled with a smart-grid that can eliminate the ... more We propose to demonstrate a smart-home solution coupled with a smart-grid that can eliminate the cost of battery backups used in the developing world. We are developing a smart-home application, SoftUPS, that instruments a home and enforces lower levels of power consumption, providing a way for a grid to reduce demand and prevent whole-scale blackouts. We have built hardware to enable such control and will demonstrate this control using a Lab-of-Things application.

Proceedings of the 2013 ACM SIGSAC conference on Computer & communications security - CCS '13, 2013

ACM SIGCOMM Computer Communication Review, 2014

With only access billing no longer ensuring profits, an ISP's growth now relies on rolling ou... more With only access billing no longer ensuring profits, an ISP's growth now relies on rolling out new and differentiated services. However, ISPs currently do not have a well-defined architecture for rapid, cost-effective, and scalable dissemination of new services. We present iSDF, a new SDN-enabled framework that can meet an ISP's service delivery constraints concerning cost, scalability, deployment flexibility, and operational ease. We show that meeting these constraints necessitates an SDN philosophy for a centralized management plane, a decoupled (from data) control plane, and a programmable data plane at customer premises. We present an ISP service delivery framework (iSDF) that provides ISPs a domain-specific API for network function virtualization by leveraging a programmable middlebox built from commodity home-routers. It also includes an application server to disseminate, configure, and update ISP services. We develop and report results for three diverse ISP applicatio...