We study the performance of a UMTS downlink, as achieved by a single-user (RAKE) and a multiuser (linear MMSE) receiver with adaptive modulation and multicode in the presence of multipath fading. We advocate an adaptive transmission scheme that varies the number of virtual users and the modulation spectral efficiency in order to optimize the system throughput. Two multipath channel models are c...

Abstract In this paper hybrid ARQ is applied to DS-CDMA with minimum mean square error frequency-domain equalization (MMSE-FDE). The throughput of turbo-coded HARQ is evaluated in addition to the packet error rate (PER). DS-CDMA with MMSE-FDE can provide much better PER performance than with rake combining in a frequency-selective fading channel and the performance improves with the increase in...

Error performance of DS-CDMA is discussed over independent Rayleigh faded multipath channel employing selective Rake (SRake) receiver. Simple-to-evaluate and accurate error probabilities are given following Holtzman’s simplified improved Gaussian approximation (SIGA). Comparing with SIGA, the validity of standard Gaussian approximation (SGA) is then verified. It is shown that SGA is accurate fo...

In this paper, we analyze the trade-offs encountered when minimizing the total execution time using the rake-based applications on GPUs. We use clustering data streams as a case study, and present a rake-based implementation for it, making it more efficient in terms of memory usage. In order to maximize performance for different problem sizes and architectures, we propose a model-based auto-tun...

In this paper, we describe the design and implementation of a rake receiver for use with ultra wide band (UWB) systems. The rake receiver uses spread spectrum modulation (SSM) aided by kasami sequence generator. The combination is found to be effective in dealing with multipath fading and signal to noise ratio. The design is initially simulated using MATLAB 7.10 and is implemented using a HDL c...

The IMT-DS system is one of the approved 3G radio interface standards which employ RAKE receivers to exploit multipath diversity. This paper discusses a new dimension in DS-CDMA channel estimation, i.e., chip-level adaptive channel estimation. A novel despreader-respreader based channel estimator (DRCE) is proposed to obtain uplink (UL) channel estimates at chip-level which resolves the deficie...

Gear skiving is used as a gear finishing process to reduce distortion errors which occurred on the gears due to the heat treatment. This process is similar to gear hobbing but the difference is that the cutting tool has a negative rake angle and tooth rake offset. The present study simulates the kinematics of the cutting process with the aid of commercial CAD software and allows the precise det...

Long-code wideband CDMA receivers are for computational reasons usually based on simple matched-filter techniques, and hence suffer from multiaccess interference. To mitigate this problem, we propose computationally efficient decorrelating RAKE and MMSE receivers for the uplink of long-code CDMA systems. The decorrelating matched filter eliminates multiaccess interference by code matrix inversi...

In a Code Division Multiple Access system operating in a multipath fading channel, a bank of RAKE receivers is needed for each active user at the base station. In this paper, low-power RAKE receivers are proposed that utilize the Strength Reduction (SR) transformation technique. The SR transformation can result in remarkable savings in consumed power and silicon area. A possible disadvantage of...

Adaptive linear minimum mean square error (LMMSE) receivers for frequency selective fading channels are developed by modifying the constrained LMMSE receiver in [6]. In particular, additional constraints regarding interpath interference are imposed on the constrained optimization in [6], and simple adaptation rules are derived by converting the constrained MMSE problem into an unconstrained opt...