• In the 1950s, Lincoln Laboratory developed the spread-spectrum Noise Modulation and Correlation (NOMAC) system for improved high-frequency radio communications. The production version of NOMAC, named the F9C, generated a pseudonoise (PN) sequence at the receiving terminal in synchronism with the PN modulation of the transmitted signal. The F9C achieved as much as 17 dB of jamming protection. ...

In this paper, the performance of DS-UWB and THUWB for a single-user link are compared for a data rate of 100 Mbps using the newly proposed, realistic UWB channel model from IEEE P802.15. The performance of suboptimal, fractionally spaced (FS), coherent Rake receivers with a pulse-matched filter is numerically evaluated with two channel estimation algorithms. DS-UWB and TH-UWB with antipodal mo...

The Rake receiver for wavelet video compression with four levels of unequal error protection (UEP) codes in wide-band code division multiple access (W-CDMA) system over additive white Gaussian noise (AWGN) and Rayleigh fading channels are performed and evaluated. The deployment of Wavelets has approached a powerful technique for compressing video sequence. The wavelet transform compression tech...

It has been reported by White (1940), Rake, McKee, and Jones (1942), White and Hill (1943), Jones, Rake, and Hamre (1943), and Bush, Dickison, Ward, and Avery (1945) that the fungus Aspergillusflavus produces an antibiotic substance known as aspergillic acid. Aspergillusflavus is also known to produce other antibiotic substances such as flavacidin (McKee, Rake, and Houck, 1943; McKee and MacPhi...

The Pre-Rake diversity combining technique decreases the complexity, size and cost of the mobile unit while achieving the same inter symbol interference (ISI) mitigation effects of conventional Rake receiver for direct sequence code division multiple access (DS-CDMA) systems. The technique is based on preprocessing of signal at the transmitter relying on knowledge of the channel state informati...

In this paper, we improve the performance analysis of the Rake receiver for the DS-CDMA forward link using long random spreading sequences (RSS’s) [15] by more accurately evaluating the correlation between the various interference terms. We also extend the analysis to the case of short (periodic) RSS. The accuracy of the expressions obtained in our analysis is verified by computer simulation. W...

One of the biggest draw back of wireless environment is the limited bandwidth. However, the users sharing this limited bandwidth have been increased considerably by using SDMA technique that can enhance the capacity of communication system. There are some techniques that can increase the capacity of the cellular system, these areSpreading Technique, Error Control Coding Technique, Multipath Div...

Wideband CDMA (WCDMA), a widely accepted thirdgeneration interface, is based on direct-sequence (DS) CDMA technology. To minimize distortion of the signals in a DSCDMA system, a rake receiver is used. A signal transmitted through the wireless channel may be severely distorted due to co-channel interference, adjacent channel interference (or multiple access interference), thermal noise, and mult...

Receivers for long-code systems are for computational reasons usually based on simple matched-filter techniques, and hence suffer frommultiaccess interference. Decorrelating RAKE andMMSE receivers do not have this problem but have not been widely studied due to the apparent complexity of the inversion of a large code matrix. Tong, van der Veen Dewilde, and Sung (IEEE Tr. Signal Proc., 2003) der...

Spread-spectrum systems are used to transmit over frequency selective fading channels. The RAKE receiver is a well-established technique to exploit the multipath diversity. However, if the channel impulse response (CIR) is known a priori in the transmitter, the signal can be precoded to increase the SNR at the receiver while the transmit power remains constant. Because the channel can be assume...