S.S. Panwar

Polytechnic Institute of New York University, Brooklyn, New York, United States

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Publications (126)50.64 Total impact

  • Huawen Ye, Zhong-Ping Jiang, Shivendra S Panwar
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    01/2011;
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    Shunyuan Ye, Marina Thottan, Jesse Simsarian, Shivendra S. Panwar
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    ABSTRACT: The rapid increase in Internet traffic is forcing packet routers to grow in capacity to meet the demand. Optical packet routers with less buffering and a greater degree of optical transparency are actively being researched as a way to improve energy efficiency and capacity scaling over traditional electronic routers. Since it is difficult to buffer packets in the optical domain, in this paper we analyze the performance of a hybrid optoelectronic packet router. The router architecture has multiple optical switch planes and a shared electronic buffer to resolve output-port contention. By using multiple ports on the switch planes for each input and output fiber, and by using some switch-plane ports to inter-connect the planes, we can achieve a relatively low packet loss ratio in a router with no buffer. In this case, most traffic can be switched using only the through optical paths of the router without entering the shared buffer. The shared electronic buffer is primarily used to reduce the packet drop ratio under periods of heavy loads and occasionally for optical regeneration of a packet.We run extensive simulations to evaluate the performance of the router with varying number of switch plane ports, number of connections to the electronic buffer, and number of interconnections between the switch planes. We show that the router can provide good throughput, with realistic on-off bursty traffic and asynchronous packet arrivals.
    Proceedings of the 12th IEEE International Conference on High Performance Switching and Routing, HPSR 2011, 4-6 July 2011, Cartagena, Spain; 01/2011
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    ABSTRACT: Internet traffic has increased at a very fast pace in recent years. The traffic demand requires that future packet switching systems should be able to switch packets in a very short time, i.e., just a few nanoseconds. Algorithms with lower computation complexity are more desirable for this high-speed switching design. Among the existing algorithms that can achieve 100% throughput for input-queued switches for any admissible Bernoulli traffic, ALGO3 and EMHW have the lowest computation complexity, which is O(logN), where N is the number of ports in the switch. In this paper, we propose a randomized scheduling algorithm, which can also stabilize the system for any admissible traffic that satisfies the strong law of large number. The algorithm has a complexity of O(1). Since the complexity does not increase with the size of a switch, the algorithm is highly scalable and a good choice for future high-speed switch designs. We also show that the algorithm can be implemented in a distributed way by using a low-rate control channel. Simulation results show that the algorithm can provide a good delay performance as compared to algorithms with higher computation complexity.
    Communication, Control, and Computing (Allerton), 2010 48th Annual Allerton Conference on; 11/2010
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    Oezgue Alay, Zhili Guo, Yao Wang, Elza Erkip, Shivendra Panwar
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    ABSTRACT: In this paper, a cooperative multicast scheme that uses Randomized Distributed Space Time Codes (R-DSTC), along with packet level Forward Error Correction (FEC), is studied. For the source packets, two-hop transmission is considered, where a packet is transmitted first by the access point (AP), and then forwarded using R-DSTC by the nodes that receive the packet. On the other hand, parity packets are generated by the nodes that receive all the source packets correctly and are transmitted using R-DSTC. The optimum transmission rates for source and parity packets, as well as the number of parity packets required, are determined such that the video quality at all nodes is maximized. It is shown that this scheme can support a higher video rate than a previously developed R-DSTC based scheme where both source and parity packets go through a two-hop transmission, as well as non-cooperative direct transmission.
    Personal Indoor and Mobile Radio Communications (PIMRC), 2010 IEEE 21st International Symposium on; 10/2010
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    ABSTRACT: Wireless video multicast enables delivery of popular events to many mobile users in a bandwidth efficient manner. However, providing good and stable video quality to a large number of users with varying channel conditions remains elusive. In this paper, an integration of layered video coding, packet level forward error correction, and two-hop relaying is proposed to enable efficient and robust video multicast in infrastructure-based wireless networks. First, transmission with conventional omni-directional antennas is considered where relays have to transmit in non-overlapping time slots in order to avoid collision. In order to improve system efficiency, we next investigate a system in which relays transmit simultaneously using directional antennas. In both systems, we consider a non-layered configuration, where the relays forward all received video packets and all users receive the same video quality, as well as a layered setup, where the relays forward only the base-layer video. For each system setup, we consider optimization of the relay placement, user partition, transmission rates of each hop, and time scheduling between source and relay transmissions. Our analysis shows that the non-layered system can provide better video quality to all users than the conventional direct transmission system, and the layered system enables some users to enjoy significantly better quality, while guaranteeing other users the same or better quality than direct transmission. The directional relay system can provide substantial improvements over the omni-directional relay system. To support our results, a prototype is implemented using open source drivers and socket programming, and the system performance is validated with real-world experiments.
    IEEE Transactions on Circuits and Systems for Video Technology 09/2010; 20(8-20):1095 - 1109. DOI:10.1109/TCSVT.2010.2056951 · 2.26 Impact Factor
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    ABSTRACT: The promise of a buffered crossbar switch - a crossbar switch with a packet buffer at each crosspoint - is that it can provide good delay performance with much less complex, practical scheduling algorithms. With today's technology, it is now possible to implement it in a single chip. Thus it has attracted great attention recently. Though simple distributed algorithms can achieve 100% throughput under uniform traffic, so far there are no distributed algorithms which can achieve 100% throughput under general admissible arrival patterns. In this paper, we propose a distributed scheduling algorithm which achieves 100% throughput for any admissible Bernoulli arrival traffic. To the best of our knowledge, this is the first distributed algorithm which can achieve this. The algorithm is called DISQUO: DIStributed QUeue input-Output scheduler. Our simulation results also show that DISQUO can provide good delay performance for different traffic patterns.
    High Performance Switching and Routing (HPSR), 2010 International Conference on; 07/2010
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    A. Rath, Sha Hua, S.S. Panwar
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    ABSTRACT: The ever increasing user demand for highly data-intensive applications is motivating cellular operators to provide more data services. However, the operators are suffering from the heavy budgetary burden of upgrading their infrastructure. Most macrocell Base Stations still connect to backhauls with capacities of less than 8 Mbps, much too low to be able to serve all voice and data users in the cell. This so-called macrocell backhaul bandwidth shortage problem is encumbering the growth of cellular data services. In this paper, we propose a novel solution, FemtoHaul , which efficiently exploits the potential of femtocells to bear the macrocell backhaul traffic by using relays, enhancing the data rates of cellular subscribers. We design a system architecture and its related signaling and scheduling strategies. Extensive simulations demonstrate that FemtoHaul can effectively serve more users and support higher data demand with the existing macrocell backhaul capacity.
    INFOCOM IEEE Conference on Computer Communications Workshops , 2010; 04/2010
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    Sha Hua, Yang Guo, Yong Liu, Hang Liu, S.S. Panwar
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    ABSTRACT: Mobile video broadcasting service, or mobile TV, is a promising application for 3G wireless network operators. Most existing solutions for video broadcast/multicast services in 3G networks employ a single transmission rate to cover all viewers. The system-wide video quality of the cell is therefore throttled by a few viewers close to the boundary, and is far from reaching the social-optimum allowed by the radio resources available at the base station. In this paper, we propose a novel scalable video broadcast/multicast solution, SV-BCMCS, that efficiently integrates scalable video coding, 3G broadcast and adhoc forwarding to balance the system-wide and worst-case video quality of all viewers in a 3G cell. We study the optimal resource allocation problem in SV-BCMCS and develop practical helper discovery and relay routing algorithms. Through analysis and extensive OPNET simulations, we demonstrate that SV-BCMCS can significantly improve the system-wide video quality at the price of slight quality degradation of a few viewers close to the boundary.
    Global Telecommunications Conference, 2009. GLOBECOM 2009. IEEE; 01/2010
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    Shunyuan Ye, Yanming Shen, Shivendra S. Panwar
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    ABSTRACT: Fast growing traffic for both the Internet and within data centers has lead to an increasing demand for high-speed switching systems. In this paper, we propose a fully distributed scheduling algorithm with an O(1) complexity, for a switch with an optical switching fabric. The inputs only use local queue information to make their scheduling decisions, and the switch consumes much less power than an electronic switch. Therefore, we call the switch HELIOS: High Energy-efficiency Locally-scheduled Input-queued Optical Switch. HELIOS can achieve 100% throughput for any admissible Bernoulli i.i.d traffic. To our knowledge, this is the first distributed scheduling algorithm to guarantee 100% throughput for an input-queued optical switch.
    Proceedings of the 2010 ACM/IEEE Symposium on Architecture for Networking and Communications Systems, ANCS 2010, San Diego, California, USA, October 25-26, 2010; 01/2010
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    ABSTRACT: Although there are several successful commercial deployments of live P2P streaming systems, the current designs; lack incentives for users to contribute bandwidth resources; lack adaptation to aggregate bandwidth availability; and exhibit poor video quality when bandwidth availability falls below bandwidth supply. In this paper, we propose, prototype, deploy, and validate LayerP2P, a P2P live streaming system that addresses all three of these problems. LayerP2P combines layered video, mesh P2P distribution, and a tit-for-tat-like algorithm, in a manner such that a peer contributing more upload bandwidth receives more layers and consequently better video quality. We implement LayerP2P (including seeds, clients, trackers, and layered codecs), deploy the prototype in PlanetLab, and perform extensive experiments. We also examine a wide range of scenarios using trace-driven simulations. The results show that LayerP2P has high efficiency, provides differentiated service, adapts to bandwidth deficient scenarios, and provides protection against free-riders.
    IEEE Transactions on Multimedia 12/2009; DOI:10.1109/TMM.2009.2030656 · 1.78 Impact Factor
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    ABSTRACT: With the increased popularity of mobile multimedia services, efficient and robust video multicast strategies are of critical importance. In a conventional multicast system, the source station transmits at the base rate of the underlying network so that all the nodes can receive the data correctly. The performance of such a multicast system is limited by the node with the worst channel conditions, which usually corresponds to the nodes at the edge of the multicast coverage range. To overcome this problem, we propose a two-hop cooperative transmission scheme where in the first hop the source station transmits the packets and the nodes who receive the packets forward the packets simultaneously in the second hop using randomized distributed space time codes (R-DSTC). We further integrate this randomized cooperative transmission with layered video coding to provide users different video quality based on their channel conditions. The performance of the system is evaluated and compared with a conventional multicast system. Our results show that the proposed cooperative system significantly improves the performance compared to conventional multicast.
    INFOCOM Workshops 2009, IEEE; 05/2009
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    Shunyuan Ye, S. Panwar
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    ABSTRACT: Carrier sensing has been used as an effective way to reduce collisions and exploit spatial reuse in wireless networks. Previous research has attempted to tune the carrier sensing range to maximize the network throughput. However, the impact of carrier sensing threshold on the probability of successful transmission has been ignored. In this paper, we derive an analytical model to calculate the successful transmission probability. We then calculate the throughput of routing protocols using different link metrics. To the best of our knowledge, this perhaps is the first attempt to derive the throughput of routing protocols like expected transmission count (ETX) [1] and expected transmission time (ETT) [2] in wireless networks. We also investigate the impact of some other important factors, such as node density, average contention window size and packet length. Our results show that optimal routing protocols that are using ETT as the path metric can achieve around 30% more throughput than those using ETX and End-to-end delay. Compared to the minimum hop count protocols such as DSR and AODV, the optimal routing protocol can improve the throughput by up to 100%.
    Wireless Communications and Networking Conference, 2009. WCNC 2009. IEEE; 05/2009
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    ABSTRACT: Cooperative communication fully leverages the broadcast nature of the wireless channel and spatial diversity, thereby achieving tremendous improvements in system capacity and delay. A cross-layer implementation approach has been pursued in this demonstration, in order to confirm the viability and efficacy of cooperation at the MAC layer, in conjunction with the routing layer, in multi-hop ad-hoc networks. In the cooperative MAC protocol, a station would use a neighboring helper station for MAC layer forwarding, if the two-hop relaying yields to a better performance than a direct single-hop transmission. In this cross layer scheme, the DSDV routing protocol defines a multihop path from the source to the destination, while the cooperative MAC scheme, eventually selects two hop forwarding for each routing layer hop, in order to boost the performance of the routing protocol. The Cooperative MAC scheme has been implemented in the MadWiFi driver, while the DSDV routing protocol has been implemented in the Click modular router. In the demo, a video clip is streamed from a server to a remote client, where the received video is played out in real time. The basic route is discovered by the DSDV routing protocol that runs on every station. The underlying MAC implementation would dynamically alternate between IEEE 802.11 g and the cooperative MAC protocol, for each route hop. In the multi-hop, ad-hoc network, the cooperative cross-layer scheme delivers a smooth user experience while the video playout over the legacy IEEE 802.11 g has noticeable freezes and frequent distortions. The demo verifies the extensibility of the cooperative MAC protocol into multi-hop ad-hoc networks, where in conjunction with the routing protocol, can achieve superior performance, compared to the legacy IEEE 802.11 g.
    Testbeds and Research Infrastructures for the Development of Networks & Communities and Workshops, 2009. TridentCom 2009. 5th International Conference on; 04/2009
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    T. Korakis, M. Knox, E. Erkip, S. Panwar
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    ABSTRACT: Cooperative networking, by leveraging the broadcast nature of the wireless channel, significantly improves system performance and constitutes a promising technology for next-generation wireless networks. Although there is a large body of literature on cooperative communications, most of the work is limited to theoretical or simulation studies. To impact the next generation of wireless technologies and standards, it is essential to demonstrate that cooperative techniques indeed work in practice. This article describes two programmable cooperative communication testbeds built at Polytechnic Institute of NYU to achieve this goal. The testbeds are based on open-source platforms and enable implementation of cooperative networking protocols in both the physical and the medium access control layer. Extensive experiments carried out using the testbeds suggest not only that cooperative communication techniques can be integrated into current wireless technologies, but also that significant benefits of cooperation can be observed in terms of network throughput, delay, and video quality in real applications.
    IEEE Communications Magazine 03/2009; DOI:10.1109/MCOM.2009.4785391 · 4.46 Impact Factor
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    O. Alay, T. Korakis, Yao Wang, S. Panwar
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    ABSTRACT: Video multicast over wireless local area networks (WLANs) faces many challenges due to varying channel conditions and limited bandwidth. A promising solution to this problem is the use of packet level forward error correction (FEC) mechanisms. However, the adjustment of the FEC rate is not a trivial issue due to the dynamic wireless environment. This decision becomes more complicated if we consider the multi-rate capability of the existing wireless LAN technology that adjusts the transmission rates based on the channel conditions and the coverage range. In order to explore the above issues we conducted an experimental study of the packet loss behavior of the IEEE 802.11b protocol. In our experiments we considered different transmission rates under the broadcast mode in indoor and outdoor environments. We further explored the effectiveness of packet level FEC for video multicast over wireless networks with multi-rate capability. In order to evaluate the system quantitatively, we implemented a prototype using open source drivers and socket programming. Based on the experimental results, we provide guidelines on how to efficiently use FEC for wireless video multicast in order to improve the overall system performance. We show that the Packet Error Rate (PER) increases exponentially with distance and using a higher transmission rate together with stronger FEC is more efficient than using a lower transmission rate with weaker FEC for video multicast.
    Consumer Communications and Networking Conference, 2009. CCNC 2009. 6th IEEE; 02/2009
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    O. Alay, T. Korakis, Yao Wang, S. Panwar
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    ABSTRACT: Wireless video multicast enables delivery of popular events to many mobile users in a bandwidth efficient manner. However, providing good and stable video quality to a large number of users with varying channel conditions remains elusive. A promising solution to this problem is the use of packet level (FEC) mechanisms. However, the adjustment of the FEC rate is not a trivial issue due to the dynamic wireless environment. This decision becomes more complicated if we consider the multi-rate capability of the existing wireless LAN technology that adjusts the transmission rates based on the channel conditions and the coverage range. In this paper, we explore the dynamics of Forward Error Correction (FEC) schemes in multi-rate wireless local area networks. We study the fundamental behavior of a 802.11g network which already has embedded error correction in physical layer, under unicast and broadcast modes in a real outdoor environment. We then explore the effectiveness of packet level FEC over wireless networks with multi-rate capability. In order to evaluate the system quantitatively, we implemented a prototype using open source drivers, and ran experiments. Based on the experimental results, we provide guidelines on how to efficiently use FEC for wireless multicast services in order to improve the overall system performance. We argue that even there is a physical layer error correction, using a higher transmission rate together with stronger FEC is more efficient than using a lower transmission rate with weaker FEC for multicast.
    Consumer Communications and Networking Conference, 2009. CCNC 2009. 6th IEEE; 02/2009
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    ABSTRACT: Cooperative communication is a promising approach to improve the reliability of a received signal at the physical layer. Cooperating nodes create a virtual MIMO system that provides spatial diversity even though the nodes have a single antenna. Therefore, tremendous improvements in system capacity and delay can be achieved. An implementation approach has been pursued in this demonstration to confirm the viability and efficacy of cooperation at the physical layer. The implemented cooperative physical layer scheme is called CoopPHY and is based on cooperative coding. In this technique, the source node transmits only a portion of its encoded data bits based on channel conditions among cooperating nodes. Helper nodes transmit the rest of the encoded bits. The destination node, finally, combines and decodes signals received via different channels and therefore increases the decoding reliability. In this demo, a Matlab video clip is streamed frame by frame from a source to destination node using sequentially the direct communication scheme, relaying via one helper, relaying via another helper and finally cooperative scheme. CoopPHY protocol delivers a smooth user experience, while the video playout over the direct scheme shows frequent distortions. In addition to this cooperative coomunication shows better quality than just relaying via any of the helpers.
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    ABSTRACT: There has been a tremendous increase in demand for real-time video applications over military networks. Multicast provides an efficient solution for simultaneous content delivery to a group of users. It is especially valuable for military applications, as it saves network resources by sharing the data streams across receivers. Even with ever increasing channel bandwidth and computation power, efficiently multicasting video over the tactical edge is still challenging due to factors such as higher packet loss ratio, bandwidth variations and the heterogeneity of the users. In this paper, we explore the use of omni-directional relays to improve the performance of wireless video multicast in tactical environments. We focus on assessing the trade-off between total relay energy, coverage area and video quality. The results provide achievable operational regions, which can serve as a reference and a starting point for system design.
    Military Communications Conference, 2008. MILCOM 2008. IEEE; 12/2008
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    Yihan Li, Shiwen Mao, Shivendra Panwar, Scott Midkiff
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    ABSTRACT: It has been shown in the literature that many MAC protocols for wireless networks have a considerable control overhead, which limits their achievable throughput and delay performance. In this paper, we study the problem of improving the efficiency of MAC protocols. We first analyze the popular p- Persistent CSMA scheme and show that it does not achieve 100% throughput.Motivated by insights from polling system theory, we then present three polling service-based MAC schemes, termed PSMACs, for improved performance. The main idea is to serve multiple data frames after a successful contention resolution, thus amortizing the high control overhead and making the protocols more efficient. We present analysis and simulation studies of the proposed schemes. Our results show that PSMAC can effectively improve the throughput and delay performance of p-Persistent CSMA, as well as providing energy savings. We also observe that PSMAC is more efficient for handling the more general and challenging bursty traffic and outperforms p-Persistent CSMA with respect to fairness.
    IEEE Transactions on Wireless Communications 12/2008; DOI:10.1109/T-WC.2008.070666 · 2.76 Impact Factor
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    ABSTRACT: We consider the design of an open P2P live-video streaming system. When designing a live video system that is both open and P2P, the system must include mechanisms that incentivize peers to contribute upload capacity. We advocate an incentive principle for live P2P streaming: a peerpsilas video quality is commensurate with its upload rate. We propose substream trading, a new P2P streaming design which not only enables differentiated video quality commensurate with a peerpsilas upload contribution but can also accommodate different video coding schemes, including single-layer coding, layered coding, and multiple description coding. Extensive trace-driven simulations show that substream trading has high efficiency, provides differentiated service, low start-up latency, synergies among peers with different Internet access rates, and protection against free-riders.
    Network Protocols, 2008. ICNP 2008. IEEE International Conference on; 11/2008

Publication Stats

2k Citations
50.64 Total Impact Points

Institutions

  • 2006–2014
    • Polytechnic Institute of New York University
      • Department of Electrical and Computer Engineering
      Brooklyn, New York, United States
  • 2013
    • NYU Langone Medical Center
      New York, New York, United States
    • City University of New York - Brooklyn College
      Brooklyn, New York, United States
  • 2010
    • New York University
      New York, New York, United States
  • 2008
    • Indian Institute of Technology Kanpur
      • Department of Computer Science & Engineering
      Cawnpore, Uttar Pradesh, India
  • 2007
    • Auburn University
      • Department of Electrical & Computer Engineering
      Auburn, AL, United States
  • 2005
    • Walailak University
      Changwat Nakhon Si Thammarat, Nakhon Si Thammarat, Thailand
  • 2004
    • Virginia Polytechnic Institute and State University
      • Department of Electrical and Computer Engineering
      Blacksburg, VA, United States
  • 1999
    • Telcordia Technologies
      Middlesex, New Jersey, United States
  • 1997
    • AT&T Labs
      Austin, Texas, United States