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Code synchronization is a critical step for fast and reliable code search in direct-sequence spread-spectrum (DS-SS) system. In this paper, we propose a novel differentially coherent (DC) detection scheme for rapid code acquisition over a fast Rayleigh fading mobile radio channel with frequency offset, and compare the performance with the conventional I-Q noncoherent detection scheme. Numerical results...
The vast literature on power control for CDMA systems ignored the fact that propagation delays occur inevitably during data communication between the base station and the mobile units or viceversa. If these delays are not considered into the power control design stage, the performance of the resulting feedback system can be severely deteriorated or even instability could be triggered in a practical...
In this paper, performance analyses of Direct Sequence Code Division Multiplexing (DS-CDMA), Multi-Tone (MT) CDMA, Multi-Carrier (MC) CDMA and MC-DS-CDMA transmission systems are carried out in a mobile radio environment. The analysis is conceded out to find the carrier to Multi-Access Interference (MAI) considering a Rake receiver. The expression of Bit Error Rate (BER) is found with respect to number...
Co existence of Global Positioning System services (GPS) with cellular and other services and features in a mobile handset presents challenges to GPS performance. Particularly challenging is the over the air (OTA) interface to the GPS receiver that results from carriers like the Global System for Mobile (GSM) and Wideband Code Division Multiple Access (WCDMA) where the transmit (TX) section of the...
The need for self-managing multihop MANETs (mobile ad hoc networks) arose recently, where the network rapidly adapts to the changes of the environment without any central control. One of the challenges is how to spread the information fast and resource-effectively in the network. This paper presents a novel adaptive framework, which utilizes natural selection for choosing the adequate message forwarding...
A new differential transceiver with frequency-shift orthogonal keying (FSOK) technique is proposed for the multi- carrier spread spectrum (MC-SS) system over the fast changing frequency selective fading channels. The design of the transceiver involves the following procedures. First, the data stream is mapped into QPSK-FSOK symbols and spreaded by the frequency-shift orthogonal sequences. Second,...
In this paper, we outline a framework for achieving high data rate connectivity in a multi-hop vehicular network. The data streams are sent to the receiver on the highest data rate path from the source vehicles. The method does not rely upon a location service for obtaining position information. Moreover, as the source and the receivers move from one position to the other, the paths are recomputed...
In this paper we study the performance of orthogonal poly-phase (OPP) sequences on the uplink of asynchronous code division multiple access (CDMA) systems. We explore the application of dynamic code allocation (DCA) of OPP sequences with the objective to minimize multiple access interference (MAI), arising due to the asynchronous transmission, and enhance the system's overall performance. Two DCA...
In this paper, an enhanced architecture for wide band data transfer based on a true differential modulation is presented, showing extremely high resistance against dispersion and fading due to multi-path propagation. The proposed system operates well with minor frequency stabilizing requirements and is characterized by a low part count. Since the modulation is based on the phase difference between...
Multicarrier code-division multiple access (MCCDMA) system with adaptive frequency hopping (AFH) has attracted attention of researchers due to its excellent spectral efficiency. A suboptimal water-filling (WF) channel allocation algorithm was previously proposed for the reverse link of this system. To overcome the limitations of the WF algorithm in the presence of fading-induced near-far problem,...
Spread spectrum technology can effectively solve the problems such as bad channel environment, multi-path fading etc between mobile station and subscribers. At present the research on the synchronization of PN code is more concentrated on how to implement fast acquisition. This paper introduces the sliding correlation method of PN code acquisition, gives out a serial and parallel acquisition method...
A full digital intermediate frequency (IF) differential BPSK direct sequence spread spectrum receiver platform is introduced. In the receiver the FPGA chip based hardware design is adopted and digital signal processing algorithm is combined to realize signal acquisition, tracking and demodulation. A scheme of a parallel combined serial acquisition is applied, and the Tong decision algorithm is also...
The orthogonal frequency division multiplex (OFDM), which is at the heart of many digital broadcasting and wireless standards, is very sensitive to Doppler spread induced by time variations of the mobile channel. This undesirable effect can be particularly detrimental to system performance when such a system is used for vehicular reception at high frequency bands since the maximum Doppler frequency...
This paper studies the effect of movement around a circular path mainly around a round about on a WCDMA receiver performance, the paper shows how to model this effect through a laboratory experiment; it explains what related parameters that control the moving propagation behaviour are. A number of scenarios are presented which show how the received signal behaves at the receive side due to the mobile...
The high-speed downlink packet access (HSDPA) communication protocol improves downlink performance on mobile networks and is currently being deployed in networks around the world. In Norway, two operators started offering this service in 2007. This article discusses performance measurements done in Telenorpsilas HSDPA network in Oslo in the context of video streaming. In particular, we present the...
Cell overloading is a bandwidth efficient scheme to increase the number of users in a fixed bandwidth for mobile applications. One of the efficient schemes to overload a CDMA system is to use two sets of orthogonal signal waveforms (O/O) [2]. An iterative soft decision interference cancellation receiver (SDIC) scheme is used to cancel interference between the two sets of users. In this paper, the...
The IEEE802.15.4a Task Group for wireless personal area networks (WPAN) is working on an ultra-wideband (UWB) radio standard for the indoor sensor network applications. In 4a Task Group, various modulation and signal sources are being proposed to find the sensor network solutions satisfied with low cost and low power consumption. Among of them, the non-coherent direct sequences (DS) chaotic system...
In this paper, we propose a cognitive radio-based multi-user resource allocation framework for mobile ad hoc networks using multi-carrier DS CDMA modulation over a frequency-selective fading channel. In particular, given pre-existing communications in the spectrum where the system is operating, in addition to potential narrow-band interference, a channel sensing and estimation mechanism is provided...
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