Now showing items 1-20 of 26

    • 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 ...
    • Efficient VLSI Architectures for Baseband Signal Processing for Wireless Base-Station Receivers 

      Rajagopal, Sridhar; Bhashyam, Srikrishna; Cavallaro, Joseph R.; Aazhang, Behnaam (2000-07-20)
      A real-time VLSI architecture is designed for multiuser channel estimation, one of the core base-band processing operations in wireless base-station receivers. Future wireless basestation receivers will need to use ...
    • Efficient VLSI architectures for multiuser channel estimation in wireless base-station receivers 

      Rajagopal, Sridhar; Bhashyam, Srikrishna; Cavallaro, Joseph R.; Aazhang, Behnaam (2002-06-20)
      This paper presents a reduced-complexity, fixed-point algorithm and efficient real-time VLSI architectures for multiuser channel estimation, one of the core baseband processing operations in wireless base-station receivers ...
    • Fast Multi-user Detector for a Time-varying CDMA System 

      Das, Suman; Cavallaro, Joseph R.; Aazhang, Behnaam (1997-07-01)
      This paper investigates methods to reduce the amount of computation needed to detect information bits using a linear detector for a CDMA system. We show windowing technique coupled with pipelining can reduce the amount of ...
    • Gradient Estimation for Sensitivity Analysis and Adaptive Multiuse Interface Rejection in Code-division Multiple-access Systems 

      Mandayam, Narayan B.; Aazhang, Behnaam (1997-07-20)
      In this paper, we consider a direct-sequence code-division multiple-access (DS-CDMA) system in the framework of a discrete-event dynamic system (DEDS) in order to optimize the system performance. Based on this formulation, ...
    • Gradient Estimation for Stochastic Optimization of Optical Code-Division Multiple-Access Systems: Part I -- Generalized Sensitivity Analysis 

      Mandayam, Narayan B.; Aazhang, Behnaam (1997-05-20)
      For optimizing the performance of optical code-division multiple-access (CDMA) systems, there is a need for determining the sensitivity of the bit-error rate (BER) of the system to various system parameters. Asymptotic ...
    • Joint signaling strategies for approaching the capacity of twisted-pair channels 

      Sendonaris, Andrew; Veeravalli, Venugopal V.; Aazhang, Behnaam (1998-10-20)
      A technique is presented for jointly optimizing the signaling in the two directions of transmission on a twisted-pair communications channel. It is then applied to twisted-pair channel models with monotonic channel response ...
    • Low Complexity Iterative Multiuser Detection and Decoding for Real-Time Applications 

      Das, Suman; Erkip, Elza; Cavallaro, Joseph R.; Aazhang, Behnaam (2005-07-01)
      This paper presents a low-complexity multiuser decoding technique that can be implemented in real time for a convolutionally coded direct sequence code division multiple access (DS-CDMA) system. The main contribution, ...
    • Maximum Likelihood Multipath Channel Parameter Estimation in CDMA Systems 

      Sengupta, Chaitali; Hottinen, Ari; Cavallaro, Joseph R.; Aazhang, Behnaam (1998-03-01)
      The problem addressed in this paper is the estimation of the channel parameters in a Code Division Multiple Access(CDMA) communication system, in the presence of multipath effects. Maximum likelihood estimation of these ...
    • Maximum Weight Basis Decoding of Convolutional Codes 

      Das, Suman; Erkip, Elza; Cavallaro, Joseph R.; Aazhang, Behnaam (2002-11-01)
      In this paper we describe a new suboptimal decoding technique for linear codes based on the calculation of maximum weight basis of the code. The idea is based on estimating the maximum number locations in a codeword which ...
    • 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 ...
    • Multitier Wireless Communications 

      Aazhang, Behnaam; Cavallaro, Joseph R. (2001-06-20)
      Next-generation computing systems will be highly integrated using wireless networking. The Rice Everywhere NEtwork (RENE) project is exploring the integration of WCDMA cellular systems, high speed wireless LANs, and home ...
    • Multitier Wireless Systems 

      Aazhang, Behnaam; Cavallaro, Joseph R. (2000-05-01)
      Next-generation computing systems will be highly integrated using wireless networking. The Rice Everywhere NEtwork (RENE) project is exploring the integration of WCDMA cellular systems, high speed wireless LANs, and home ...
    • Multiuser detection in fast-fading multipath environments 

      Sayeed, Akbar M.; Aazhang, Behnaam (2001-10-20)
      We propose a new framework for multiuser detection in fast-fading channels that are encountered in many mobile communication scenarios. Existing multiuser RAKE receivers, developed to combat multipath fading and multiuser ...
    • Multiuser detection in fast-fading multipath environments 

      Sayeed, Akbar M.; Sendonaris, Andrew; Aazhang, Behnaam (1998-12-20)
      We propose a new framework for multiuser detection in fast-fading channels that are encountered in many mobile communication scenarios. Existing multiuser RAKE receivers, developed to combat multipath fading and multiuser ...
    • 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 Multipath Channel Estimation for CDMA Systems Using Multiple Sensors 

      Sengupta, Chaitali; Cavallaro, Joseph R.; Aazhang, Behnaam (2001-03-20)
      This paper focuses on the design of a multiuser receiver structure for the reverse link of a code-division multiple-access communication system, in the presence of multipath effects and using an antenna array at the base ...
    • 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 ...