Now showing items 21-40 of 134

  • Cyclic spreading codes for CDMA systems 

    Lu, Jin; Aazhang, Behnaam (1997-10-20)
    In this paper, we propose a CDMA system using cyclic convolutional matched filter. The multiple access interference in this system is small under arbitrary relative delays
  • 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 DOA estimation in CDMA communication systems via maximum likelihood techniques 

    Madyastha, Raghu; Aazhang, Behnaam (1997-10-20)
    We present a maximum likelihood method for delay estimation in a CDMA wireless communication system. An antenna array is used at the receiver, which facilitates the concomitant estimation of the direction of arrival (DOA) ...
  • 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 bounded packet scheduling of bursty traffic over wireless channels 

    Rajan, Dinesh; Sabharwal, Ashutosh; Aazhang, Behnaam (2004-01-01)
    In this paper, we study minimal power transmission of bursty sources over wireless channels with constraints on mean queuing delay. The power minimizing schedulers adapt power and rate of transmission based on the queue ...
  • Demonstration of all-optical CDMA with bipolar codes 

    Dennis, Tasshi; Aazhang, Behnaam; Young, James F. (1996-10-20)
    Using a fiber-based testbed, we experimentally verify that the advantageous correlation properties of bipolar spread-spectrum codes can be preserved in an optical channel using direct detection and all-optical encoder/decoders. ...
  • Design of Coded Modulation Schemes for Orthogonal Transmit Diversity 

    Borran, Mohammad Jaber; Memarzadeh, Mahsa; Aazhang, Behnaam (2001-06-20)
    In this paper, we propose a technique to decouple the problems of spatial and temporal diversity gain maximization involved in the design of space-time codes in fast Rayleigh fading channels by using orthogonal transmit ...
  • Design of Coded Modulation Schemes for Orthogonal Transmit Diversity 

    Borran, Mohammad Jaber; Memarzadeh, Mahsa; Aazhang, Behnaam (2001-05-20)
    In this paper, we propose a technique to decouple the problems of maximizing spatial diversity gain, temporal diversity gain, and coding gain, involved in the design of space-time codes in Rayleigh fading channels. For ...
  • Design of Multiple Antenna Coding Schemes with Channel Feedback 

    Mukkavilli, Krishna Kiran; Sabharwal, Ashutosh; Aazhang, Behnaam (2001-11-20)
    In this paper, we derive multiple antenna transmission strategies in the presence of limited channel information at the transmitter and the receiver. In particular, we look at the cases of complete channel information, ...
  • Design of Space Time Codes With Optimal Coding Gain 

    Mukkavilli, Krishna Kiran; Aazhang, Behnaam; Ionescu, Michael D. (2000-09-20)
    Space time codes have been proposed in the literature as an efficient means for improving the data rates over fading channels with multiple transmit antennas. In particular, the rank and the determinant of code difference ...
  • Design of space-time codes with optimal coding gain 

    Mukkavilli, Krishna Kiran; Ionescu, Michael D.; Aazhang, Behnaam (2000-10-20)
    Space time codes have been proposed in the literature as an efficient means for improving the data rates over fading channels with multiple transmit antennas. In particular, the rank and the determinant of code difference ...
  • Design of the Transit Access Point Hardware Platform 

    Murphy, Patrick; Frantz, Patrick; Aazhang, Behnaam (2005-09-01)
    Our objective is to design, analyze, prototype and experimentally study the theoretical underpinnings for a wireless internet that simultaneously achieves deployability, scalability, high performance and a cost-effective ...
  • Design of WARP: A Wireless Open-Access Research Platform 

    Murphy, Patrick; Sabharwal, Ashutosh; Aazhang, Behnaam (2006-09-01)
    This paper presents the design of WARP, a custom platform for research in advanced wireless algorithms and applications. The platform consists of both custom hardware and FPGA implementations of key communications blocks. ...
  • Distorted Channel Capacity: A Geometrical Approach 

    Das, Suman; Cavallaro, Joseph R.; Erkip, Elza; Aazhang, Behnaam (2000-06-20)
    Shannon's capacity result has often been used as a benchmark to compare the performance of practical codes. Shannon's theorem helps us to calculate the maximum rate at which data can be transferred without making any errors. ...
  • DSP architectural considerations for optimal baseband processing 

    Rajagopal, Sridhar; Rixner, Scott; Cavallaro, Joseph R.; Aazhang, Behnaam (2002-08-20)
    The data rate requirements for future wireless systems has increased by orders-of-magnitude (from Kbps to several Mbps), requiring more sophisticated algorithms for their implementation. This tutorial will explore different ...
  • Dual Problems in Power Control 

    Sabharwal, Ashutosh; Rajan, Dinesh; Aazhang, Behnaam (2001-10-20)
    In this paper, we study power control to minimize packet loss for delay-bounded transmission of bursty sources over Gaussian channels and transmission of constant rate sources over time-varying block fading channels. In ...
  • Efficient Multiuser Receivers for CDMA Systems 

    Sengupta, Chaitali; Das, Suman; Cavallaro, Joseph R.; Aazhang, Behnaam (1999-09-20)
    We focus on the design of multiuser receiver structures for Code Division Multiple Access (CDMA) communication systems, in the presence of multipath elects and multiple sensors at the base station receiver. We present a ...
  • 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 ...
  • EM-Based Multiuser Detection in Fast Fading Multipath Environments 

    Borran, Mohammad Jaber; Aazhang, Behnaam (2002-08-01)
    We address the problem of multiuser detection in fast fading multipath environments for DS-CDMA systems. In fast fading scenarios, temporal variations of the channel cause significant performance degradation even with the ...