Now showing items 1-16 of 16

    • Architectures for Cognitive Radio Testbeds and Demonstrators – An Overview 

      Gustafsson, Oscar; Amiri, Kiarash; Andersson, Dennis; Blad, Anton; Bonner, Christian; Cavallaro, Joseph R.; Declerck, Jeroen; Dejonghe, Antoine; Eliardsson, Patrik; Glasse, Miguel; Hayar, Aawatif; Hollevoet, Lieven; Hunter, Chris; Joshi, Madhura; Kaltenberger, Florian; Knopp, Raymond; Le, Khanh; Miljanic, Zoran; Murphy, Patrick; Naessens, Frederik; Nikaein, Navid; Nussbaum, Dominique; Pacalet, Renaud; Raghavan, Praveen; Sabharwal, Ashutosh; Sarode, Onkar; Spasojevic, Predrag; Sun, Yang; Tullberg, Hugo M.; Vander Aa, Tom; Van der Perre, Liesbet; Wetterwald, Michelle; Wu, Michael (2010-06-01)
      Wireless communication standards are developed at an ever-increasing rate of pace, and significant amounts of effort is put into research for new communication methods and concepts. On the physical layer, such topics include ...
    • Data Collection by a Mobile Observer in a Single-hop Sensor Network 

      Chakrabarti, Arnab; Sabharwal, Ashutosh; Aazhang, Behnaam (2005-01-15)
      In this paper, we demonstrate significant reduction in communication power by using a mobile observer to collect data from a wireless single-hop network of static sensors. The key challenge in using a mobile observer is ...
    • Delay and Rate Constrained Transmission Policies over Wireless Channels 

      Rajan, Dinesh; Sabharwal, Ashutosh; Aazhang, Behnaam (2001-11-20)
      In this paper, we study delay and rate-constrained transmission of bursty traffic over wireless channels. We characterize the minimum power requirements via bounds for both single user and multiuser downlink problems, using ...
    • Delay-constrained Scheduling: Power Efficiency, Filter Design, and Bounds 

      Khojastepour, Mohammad; Sabharwal, Ashutosh (2004-03-01)
      In this paper, packet scheduling with maximum delay constraints is considered with the objective to minimize average transmit power over Gaussian channels. The main emphasis is on deriving robust schedulers which do ...
    • FPGA in Wireless Communications Applications 

      Amiri, Kiarash; Duarte, Melissa; Cavallaro, Joseph R.; Dick, Chris; Rao, Raghu; Sabharwal, Ashutosh (2012-07-12)
      In the past decade we have witnessed explosive growth in the wireless communications industry with over 4 billion subscribers worldwide. While first and second generation systems focused on voice communications, third ...
    • MultiHop Communication is Order Optimal for Homogeneous Sensor Networks 

      Chakrabarti, Arnab; Sabharwal, Ashutosh; Aazhang, Behnaam (2004-04-01)
      The main goal of this paper is to show that multi-hop single-user communication achieves the per node transport capacity of O(lnN/N) in homogeneous sensor networks, making it order-optimal. Our contributions in this paper ...
    • On Beamforming with Finite Rate Feedback in Multiple Antenna Systems 

      Mukkavilli, Krishna Kiran; Sabharwal, Ashutosh; Erkip, Elza; Aazhang, Behnaam (2003-10-20)
      In this paper, we study a multiple antenna system where the transmitter is equipped with quantized information about instantaneous channel realizations. Assuming that the transmitter uses the quantized information for ...
    • On Design Criteria and Construction of Non-coherent Space-Time Constellations 

      Borran, Mohammad Jaber; Sabharwal, Ashutosh; Aazhang, Behnaam (2003-10-20)
      We consider the problem of digital communication in a Rayleigh flat fading environment using a multiple-antenna system, when the channel state information is available neither at the transmitter nor at the receiver. It ...
    • On the Asymptotic Performance of Multiple Antenna Channels with Fast Channel Feedback 

      Khoshnevis, Ahmad; Sabharwal, Ashutosh (2005-10-01)
      In this paper, we analyze the asymptotic performance of multiple antenna channels where the transmitter has either perfect or finite bit channel state information. Using the diversitymultiplexing tradeoff to characterize ...
    • Partially Coherent Constellations for Multiple-Antenna Systems 

      Borran, Mohammad Jaber; Sabharwal, Ashutosh; Aazhang, Behnaam; Varshney, Prabodh (2003-11-20)
      We consider the problem of digital communication in a Rayleigh flat fading environment using a multiple antenna system. We assume that the transmitter doesnâ t know the channel coefficients, and that the receiver has only ...
    • Partially Coherent Multiple Antenna Systems: Design Criterion and Construction Methods for Constellations and Coded Modulation 

      Borran, Mohammad Jaber; Sabharwal, Ashutosh; Aazhang, Behnaam (2004-01-15)
      We consider multiple-antenna communication systems in Rayleigh fading channel, where the transmitter does not know the channel coefficients and the receiver has only an estimate of them. We further assume that the transmitter ...
    • Power efficient broadcast scheduling with delay deadlines 

      Rajan, Dinesh; Sabharwal, Ashutosh; Aazhang, Behnaam (2004-10-01)
      In this paper, we present a framework for the design of minimal power schedulers that satisfy average packet delay bounds for multiple users in a Gaussian wireless broadcast channel. We completely characterize the achievable ...
    • Rate-constrained Relaying: A Model for Cooperation with Limited Relay Resources 

      Sabharwal, Ashutosh; Mitra, Urbashi (2005-06-01)
      In this paper, the impact of limited resources on achievable rates in relay channels is investigated. Resource limitation is modeled as a rate constraint, Rbar, which constrains the rate at which a relay can reliably ...
    • Using Predictable Observer Mobility for Power Efficient Design of Sensor Networks 

      Chakrabarti, Arnab; Sabharwal, Ashutosh; Aazhang, Behnaam (2003-04-20)
      In this paper, we explore a novel avenue of saving power in sensor networks based on predictable mobility of the observer (or data sink). Predictable mobility is a good model for public transportation ve- hicles (buses, ...
    • WARP, a Modular Testbed for Configurable Wireless Network Research at Rice 

      Amiri, Kiarash; Sun, Yang; Murphy, Patrick; Hunter, Chris; Cavallaro, Joseph R.; Sabharwal, Ashutosh (2007-03-01)
      Wireless Open-Access Research Platform (WARP), developed at CMC lab, Rice University, provides a scalable and configurable platform for wireless network research. Its programmability and flexibility makes it easy to prototype ...
    • WARP, a UnifiedWireless Network Testbed for Education and Research 

      Amiri, Kiarash; Sun, Yang; Murphy, Patrick; Hunter, Chris; Cavallaro, Joseph R.; Sabharwal, Ashutosh (2007-06-01)
      In this paper, we introduce the Wireless Open-Access Research Platform (WARP) developed at CMC lab, Rice University. WARP provides a scalable and configurable platform mainly designed to prototype wireless communication ...