نتایج جستجو برای: cdma چند سطحی
تعداد نتایج: 102047 فیلتر نتایج به سال:
The crop model data assimilation approach has been acknowledged as an effective tool for monitoring growth and estimating yield. However, the choice of assimilated variables mismatch in scale between remotely sensed observations model-simulated state have various effects on performance yield estimation. This study aims to examine accuracy estimation through joint leaf area index (LAI) soil mois...
In this paper, the near-far resistance of the minimum mean square error (MMSE) detector is derived for the multicarrier direct sequence code division multiple access (MC-DS-CDMA) communication systems. It is shown that MC-DS-CDMA has better performance on near-far resistance than that of DS-CDMA.
This report examines optical CDMA communication techniques with optical orthogonal codes. Simulations that show the desired properties of theses codes and their use in optical CDMA are reported. Based on the simulations, we investigate the properties of optical CDMA. Proba bility of error is also evaluated.
it is shown in [1] that the optimal downlink radio resource allocation for non-realtime traffic in cellular cdma/tdma networks can be mapped to a multi-dimensional multiple-choice knapsack problem (mmkp) which is np-hard. in this correspondence we propose a heuristic algorithm with polynomial time complexity for this problem. numerical results indicate significant computational performance impr...
در این پایان نامه با فرض اینکه برای دسترسی چندگانه کاربران از تخصیص کد به آن ها استفاده می شود (cdma)، ازآنجایی که در سیستم های cdma نیاز به کنترل توان کاربران مختلف است، به بررسی عملکرد سیستم های نوری با گیرنده های مختلف و اثر کنترل توان کاربران در آن ها می-پردازیم سپس راه کاری برای استفاده بهینه از توان با استفاده از کدینگ مناسب کانال مطرح شده است که مبتنی بر مرزبندی کانال و تقسیم آن به نواح...
This paper proposes a Multi-Code Multi-Carrier CDMA, best suited for multi-rate services using multicode schemes and multi-carrier services used for high rate transmission as required for the Universal Telecommunication Mobile Systems (UMTS) Long Term Evolution (LTE). The system performance has been analyzed and evaluated by means of signal-to-noise plus interference ratio and bit error rate un...
A Scalable hierarchical architecture based Code-Division Multiple Access (CDMA) is proposed for high performance Network-on-Chip (NoC). This hierarchical architecture provides the integration of a large number of IPs in a single on-chip system. The network encoding and decoding schemes for CDMA transmission are provided. The proposed CDMA NoC architecture is compared to the conventional archite...
Multiple-access interference reduction for QS-CDMA systems with a novel class of polyphase sequences
In this paper, a new class of polyphase sequences for CDMA systems and its generation method are suggested, and the correlation properties of the sequence are investigated. The performance of the sequence in quasi-synchronous CDMA (QS-CDMA) systems is investigated under frequency-selective, time-nonselective, slow Nakagami fading channel with additive white Gaussian noise (AWGN). It is shown th...
In this article we propose a solution for the channel decoder in a iterative CDMA receiver. The iterative CDMA receiver resembles a Turbo decoder for serially concatenated convolution codes since the CDMA channel is viewed as a convolutional code. The proposed solution has complexity per bit that is linear in the number of users. For the rst time we observe performance within a fraction of a dB...
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