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A DS-CDMA system is said to be Overloaded if the number of users supported is more than the spreading factor N. Overloading is an attractive candidate for next generation cellular telephony that calls for a higher user capacity than that supported by conventional DS-CDMA systems. This work derives an accurate analytical model for Overloaded DS-CDMA system under imperfect synchronization. The Model...
This paper proposes TD-uCSMA a synchronous distributed coordination function which is meant to provide CSMA/CA with a mechanism for QoS provisioning and bandwidth management over WiFi networks. TD-uCSMA relies on synchronization among nodes and the time-driven switching of contention parameters inside nodes. The TD-uCSMA operating principles and preliminary synchronization issues are presented here...
This paper proposes a two-level serial search-and-verification code acquisition algorithm for optical orthogonal codes (OOCs) in optical code division multiple access (O-CDMA) systems. We analyze the performance of the proposed algorithm using the Markov chain model. The results show that the proposed algorithm can reduce the mean acquisition time when compared with the existing two-level serial search...
This correspondence describes an efficient Bayesian framework for localization of moving terminals (MTs) in wideband wireless networks. In a previous paper, the authors have presented a grid-based technique, based on a hidden Markov model, that used the power delay profiles of the received signals to track the MT position. This grid-based Bayesian method has proved its efficacy in reducing localization...
In this paper, we propose a robust STBC transmission scheme to combat the timing synchronization errors over frequency-selective multiple-access channels. First, the equivalent channel model in the presence of timing synchronization errors is derived and we find that the synchronization errors result in an equivalent channel model with larger number of correlated channel taps. Based on this correlated...
We propose a more accurate method to analyze multilevel frequency-shift-keying frequency-hopping code-division multiple-access (MFSK/FH-CDMA) wireless communication systems using ldquoone-hitrdquo FH patterns, instead of random FH patterns. By also removing the over-optimistic symbol-synchronous assumption, the new method provides a more realistic performance analysis as the MFSK modulation may result...
In this paper, we address the issue of transmission power control (TPC) in wireless ad hoc networks. Power control plays an important role in energy saving and network performance enhancement. However, the existing TPC schemes either face the problem of hidden and exposed terminal or have additional hardware requirements. We propose a novel distributed power control protocol, called Receiver Initiated...
Video-streaming can now be offered on third-generation (3G) mobile networks. Most research efforts have focused on video download. This paper presents a detailed study of challenges faced for successfully deploying applications requiring life video upload. Both subjective and objective qualities as well as the effects of mobility are analyzed on real 3G networks. Consequently, video profiles are identified...
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