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QoS routing protocol has become a hot research spot. However, it is difficult to offer guaranteed QoS, such as bandwidth, delay and delay jitter. To solve this problem, we proposed a Delay-Minimized Routing protocol based on Bandwidth Estimation (DMR-BE) that incorporates an admission control scheme and a route decision scheme to meet the QoS requirement of bandwidth and real-time applications. Bandwidth...
The deep quasiperiodic variations in the part of frequency dependence of amplitude of reflections from layer Es observed by Kazan ionosonde was discovered. The analysis of height location of traces in an ionogram has shown that beatings arise because of interference between o- and x-modes. For an explanation of such interaction details a modeling is performed on the basis of calculations of coefficient...
In this paper, we propose a distributed angle estimation method for wireless sensor network localization with multipath fading. The multiple antenna system is equipped at the anchor and the angle of departure (AOD) can be estimated individually at each sensor node with single antenna system. Further, we exploit the space diversity to improve the estimation performance by deploying multiple parallel...
In this paper, a new method is proposed for delay and Doppler estimation using copula theory. Copula analysis helps to explore the underlying inter-dependence between the desired and undesired parts of a received signal. At first, the probability density function (PDF) of the desired signal is extracted analytically. This analytic result contains the simultaneous influence of delay and Doppler. Our...
This paper gives an introduction to a generic OFDM based testbed for positioning using time difference of arrival (TDoA) measurements. An overview of the transmitter system and receiver system is given. Furthermore an inital access algorithm with interference mitigation for subsample delay estimation is presented and simulation results are shown. The influence of the geographic base station mapping...
Using wireless sensor networks (WSNs) to observe physical processes for control systems has attracted much attention recently. For some real-time control applications, controllers need to accurately estimate the process state within rigid delay constraints. In this paper, we jointly consider state estimation and scheduling problems in multihop WSNs. For accurately estimating a process state as well...
Load balancing in wireless mesh networks (WMNs) is one of the major design goals for any routing protocol. In this paper, we propose AntMesh, an efficient data forwarding scheme, specifically designed for load balancing in multi-radio infrastructure WMNs. As the foundation of AntMesh, we use Ant Colony Optimization (ACO) in which artificial ants (agents) perform the routing and data forwarding to...
We present our initial work on the design and implementation of an efficient routing architecture for wireless mesh networks (WMNs). We have proposed two routing schemes namely AMIRA and AntMesh, which provide efficient data forwarding for improved load-balancing and reduced interference in single and multi-radio infrastructure mesh networks. Both of our proposed schemes are derived from the principle...
In this paper, we investigate the performance of superimposed training-based channel estimation techniques considering an asynchronous code-division multiple-access (CDMA) uplink transmission over frequency-selective fading channels. In that, we analyze the performance of a channel estimation and data detection scheme based on superimposed training for space-time spreading (STS) systems. Our results...
In this paper, an algorithm reprocessing of the power spectrum density (RPSD) is proposed to detect and estimate the PN code's period of the multipath direct sequence spread spectrum (DS/SS) signal in low SNR, which develops the previous processing method based on the single path environment. It can solve the difficult problem of PN code's period detection and estimation in multipath environment....
In the uplink of OFDMA (Orthogonal Frequency Division Multiple Access) based M-WiMAX (Mobile-Worldwide Interoperability for Microwave Access) system, linear phase shift is caused by signals transmitted from multiuser with different delay time and thus, MAI (Multiple Access Interference) occurs. MAI degrades the performance of ranging code detection and delay time estimation in the uplink. Therefore,...
In recent years, smart antenna technologies are of ever-increasing interest to boost the capacity of existing and future wireless systems. Several standards support these techniques such as the wireless metropolitan area network IEEE 802.16 (WiMAX) and IMT-Advanced candidates. In applying smart antenna beamforming and Space Division Multiple Access (SDMA) techniques, adaptive antennas are able to...
The multipath estimation delay locked loop was researched and improved through the limited points estimation method in the paper. In this paper, the structure chart of the PN code tracking loop was introduced, and the mathematics model of the signal tracking system in multipath environment was also presented. When only one multipath signal was considered, its influence to the loop discriminative character...
A novel estimation technique of timing delay and frequency offset that takes advantage of a dual-chirp signal is proposed and investigated in this paper. The proposed technique can be implemented with low hardware or computational complexity by using fully-digital circuitry or a digital signal processor (DSP). In addition, it can achieve sufficiently low errors both on timing delay and frequency offset...
Spread spectrum signals are now widely used for secure communications, as well as for multiple access interference (MAI). They have many interesting properties, including low probability of interception. Indeed, DS/SS transmitters use a periodical pseudo-random sequence to modulate the baseband signal before transmission. A receiver which does not know the sequence can not demodulate the signal. Blind...
In this paper we consider a centralized cross-layer splitting algorithm of a multi-packet reception slotted ALOHA system for contention resolution. In the algorithm, a base station estimates the number of backlogged mobile terminals by using a first-order auto-regressive (AR) model based on the number of packets successfully transmitted over previous contention resolution intervals (CRIs). Estimation...
In this paper, we present a centralized quasi-static channel assignment for multi-radio WMNs (wireless mesh networks) to provide high-throughput paths. We probe data packets at each wireless access point and estimate the traffic load for each network link using a new load estimation algorithm. So the channel assignment can intelligently assigns channels with the objective of maximizing the aggregate...
Interference cancellation is one major multiuser detection strategy for suppressing interference effects and improving system performance. In this paper, a novel blind decision-feedback interference cancellation framework and its implementations with least squares, maximum likelihood and minimum mean squared error criteria are proposed and analyzed. Compared with existing blind multiuser receivers,...
The performance of an adaptive interference canceller (AIC) is sensitive to the dasiasignal crosstalkpsila in the reference channel. This paper analyzes the performance of the crosstalk-resistant AIC at first. The transmitting function of the channel of the signal crosstalk in the cosite interference can be estimated approximately, so an additive channel is added at the input of the reference signal...
Frequency-hopped OFDM (FH-OFDM) technology will provide the additional benefits of frequency diversity and inter-cell interference averaging. However, it is difficult to get the channel state information. In this paper, we propose a method of channel estimation over slow fading channels for FH-OFDM systems. In the algorithm, the channel impulse response is estimated by correlation operation, by using...
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