Cellular radio can be regarded as the earliest form of wireless “personal communication”. It allows the subscriber to place and receive telephone calls wherever cellular coverage is provided. But with the pessage of time, it becomes more and more difficult to accomodate a large number of users within a limited frequency band. This thesis addresses capacity estimation and a review of work carrie...

The accuracy of channel estimation significantly affects the performance of coherent rake receiver in DS-CDMA systems. It is desirable for improved channel estimation to employ a channel estimation filter (CEF) whose bandwidth is adjustable to the channel condition. In this paper, we consider the use of moving average (MA) FIR filters as the CEF since it is simple to implement and can provide r...

We introduce a novel merger of direct sequence code division multiple access (DS-CDMA) and smart antenna arrays. With regard to the DS-CDMA scheme, we employ carrier interferometry DS-CDMA (CI/DS-CDMA), a novel implementation of DSCDMA where chips are decomposable into N narrowband frequency components. With regard to the antenna array, we deploy the oscillating-beam smart array. Here, applying...

The outage behaviour of the single cell DSCDMA uplink is investigated for flat Rayleigh fading channels. Goal of the work is to find an analytical way for the optimisation of the system spectral efficiency under some outage probability constraint by adjusting parameters such as modulation, spreading factor, code rate and number of codes per user. Therefore, the results of the asymptotic analysi...

This paper considers the problem of interference suppression in direct-sequence code-division multiple-access (DSCDMA) systems over fading channels. An adaptive array receiver is presented which integrates multiuser detection, beamforming, and RAKE reception to mitigate cochannel interference and fading. The adaptive multiuser detector is formulated using a blind constrained energy minimization...

The combination of Space-Time Block Coding (STBC) and Direct-Sequence Code Division Multiple Access (DSCDMA) has the potential to increase the performance of multiple users in a cellular environment. However, if not carefully designed, the resulting communication scheme suffers from increased Multi-User Interference (MUI), which dramatically deteriorates the performance. To tackle this MUI prob...

This paper concerns with a procedure of selecting the partial cancellation factor for the first stage of a hard-decision partial parallel interference cancellation of the generalized detector, which is constructed based on the generalized approach to signal processing in noise [1]–[5], in the case of direct-sequence code-division multiple access (DS-CDMA) systems. A range of the optimal partial...

This paper proposes an iterative receiver derived from recent advances in narrowband turbo equalization for the multicode transmission scheme of the downlink of DSCDMA systems with long scrambling sequences. The proposed scheme is based on a chip-rate linear equalizer exchanging soft information on the composite multiuser signal with the channel decoder in an iterative process. When all spreadi...

In this paper we present Walsh-quadrature phase-shift keying (Walsh-QPSK) pseudonoise (PN) modulation schemes for both coherent and noncoherent direct-sequence code-division multiple-access (DS-CDMA) systems, wherein the PN spreading sequences for in-phase and quadrature data in a conventional QPSK PN modulation scheme are coded by Walsh sequences indexed by a special rule to reduce the envelop...

Jung-Hun Oh et al. 177 Multicarrier DS-CDMA is an effective approach to combat fading and various kinds of interference. In this paper, we present an overlapped multicarrier DS-CDMA system, wherein each of the rate M / 1 convolutionally-encoded symbols is also repetition coded and transmitted using overlapped multicarriers. However, since the frequency spectrums of successive carriers are allow...