Spread spectrum modulation techniques are mostly employed in wireless communication systems. In order to fully understand spread spectrum communications, we need to have a basic idea on the characteristics of wireless channels. The behavior of a typical mobile wireless channel is considerably more complex than that of an AWGN channel. Besides the thermal noise at the receiver front end (which i...

| Diversity techniques provide a powerful approach to combat fading. Due to the presence of multipath and Doppler shifts, the mobile wireless channel inherently provides diversity that can be exploited using appropriate signaling and reception. While existing CDMA systems exploit only multipath diversity using spread-spectrum signaling, we develop signaling and reception schemes that exploit jo...

The diversity is used to provide the receiver with several replicas of the same signal. The diversity techniques like selection diversity, equal gain diversity and maximum ratio combining diversity have been discussed to improve the quality of service parameters in CDMA communication network. Key WordsQos, Network, Diversity, CDMA, Gain * Computer Science Department, MGM College of Engineering&...

Frequency-domain pre-equalization (pre-FDE) transmission can be used instead of FDE reception for improving the transmission performance in a severe frequency-selective fading channel. Antenna diversity technique is also a well-known technique for improving the transmission performance, especially, transmit antenna diversity technique has been attracting much attention. In this paper, we propos...

In this paper, the space time transmit diversity (STTD) decoding combined with minimum mean square error (MMSE) equalization and antenna diversity reception is presented for MC-CDMA downlink and uplink in the presence of multiple users. The equalization weights that minimize the mean square error (MSE) for each subcarrier are used. From computer simulation, it was found that the downlink BER pe...

We compare three receivers for coded narrowband transmission over a channel with fading, shadowing , and co-channel interference. The baseline receiver includes conventional diversity reception with maximal-ratio combining. A multiuser approach allows us to derive a maximum-likelihood (ML) multiuser diversity receiver and its reduced-complexity suboptimal version. Finally, a decor-relating dive...

Diversity schemes are being used on mobile cellular networks to combat the effect of multipath fading mainly at the base station site. Since digital TV will be deployed using UHF bands, this paper proposes to study the feasibility of using space diversity for the mobile digital TV reception since these kind of system is also subjected to multipath effects. This work experimentally investigates ...

Type-based receivers assume no a priori channel model, and were previously shown to be e ective in direct-sequence spread spectrum communications. In this paper, we investigate the macro-diversity combining of multiple type-based receivers in single-mobile-user reception (BPSK). We present a method for the exact calculation of the bit error rate of type-based receivers in this scenario. Maximal...

A closed form formula is derived for the bit error rate (BER) of orthogonal-frequency-division-multiplexing (OFDM) with -ary differential-phase-shift-keying (MDPSK) systems in frequency-selective Rayleigh and Rician fading channels with diversity reception. New BER curves are obtained as a function of the rms delay spread of the diffused component for three different types of delay profiles: 1)...

We consider multi-receiver networks with diversity reception from an information-theoretic point of view. In particular we nd their capacity and investigate how the frequency spectrum should be allocated to the users. We conclude that eecient transmission schemes cannot be built based on re-use partitioning and therefore advocate a spread spectrum approach. We also show that diierences in recei...