نتایج جستجو برای: سیستم چندحاملی cdma
تعداد نتایج: 80796 فیلتر نتایج به سال:
Abstract MC-CDMA, a multicarrier modulation scheme based on code division multiple access (CDMA) is the most likely candidate for the next generation of mobile radio communications. Rate compatible punctured turbo coded hybrid ARQ (RCPT HARQ) has been found to give improved throughput performance in a DS-CDMA system. In this paper, we apply RCPT HARQ to an MC-CDMA system and evaluate by compute...
This paper studies the trade-off between coding and direct-sequence spreading in a code-division multiple-access (CDMA) system, in the presence of errors in the delay estimate. One extreme is when all spreading is done by forward error correcting codes , referred to as code-spread CDMA (CS-CDMA) systems. CS-CDMA systems have been shown to achieve high capacity, assuming perfect channel knowledg...
In electronics and communication system MC-CDMA(Multi Carrier Code Division Multiple Access) is very attractive choice for high speed wireless communication with bandwidth utilization and BER(bit error rate) performance.MC-CDMA is used in wireless communication to avoid the problem of ISI(intersymbol interference) and also exploit frequency diversity.MC-CDMA system is used to support multiple u...
Multiband CDMA is useful for constructing DSCDMA (CDMA) systems over a non-contiguous spectrum. The method by which users are assigned to their respective frequency bands, termed ‘band allocation’, is an important part of assuring good performance in multiband CDMA systems. This paper proposes a novel approach to band allocation based on the transmission power as it is adjusted by power control...
In this paper we consider a matrix algebraic approach to derive the coded Multi-Carrier CDMA (MC-CDMA) system model for a Doppler shift channel. We derive the eeects of Doppler shift in a MC-CDMA system for low earth orbit (LEO) mobile-satellite communications and show the similarity of a MC-CDMA channel model under Doppler shift with that of the asynchronous DS-CDMA channel model. We therefore...
Multi-carrier code division multiple access (MCCDMA) is method for high speed data rate communication. It skip the problem of inter symbol interference.MC-CDMA too provide spatial diversity, which mitigate the fading. The usage of MC-CDMA can significantly improve the performance of wireless communication system. This paper presents the simulation of MC-CDMA system performance with MSK modulati...
Relying on block-symbol spreading and judicious design of user codes, this paper builds on a recently proposed Generalized Multicarrier (GMC) quasi-synchronous CDMA system that is capable of multiuser interference (MUI) elimination and intersymbol interference (ISI) suppression with guaranteed symbol recovery, regardless of the wireless frequency selective channels. GMC-CDMA aaords an all-digit...
a typical radio frequency identification system (rfid) includes one reader and a number of tags. the reader transmit to commands to the tags with interrogation radio signals, and tags receive the command and then respond with their identification. readers with interrogation signals can read tags’ responses. in rfid systems, when multiple tags respond to one reader simultaneously, tag collision ...
abstract this paper presents a multiobjective power control algorithm that updates the transmitted power based on local information. the proposed algorithm is expanded by using multiobjective optimization schemes. the objectives to be optimized in this paper are determined so as to reduce the sinr fluctuations as well as maintaining the sinr to an acceptable level with minimizing an average tra...
در سال های اخیر بحث محدودیت پهنای باند به دلیل رشد روزافزون تعداد مشترکین و پیشرفت کاربردهای چندرسانه ای با نرخ بالا بیش از پیش مورد توجه قرار گرفته است. شبکه-های رادیوشناختی به منظور مقابله با این محدودیت در سال 1999معرفی شدند، اما اجرایی کردن این شبکه ها با چالش ها و مشکلاتی همراه است. یکی از چالش های پیشرو برای پیاده-سازی این شبکه ها مسئله ی شناسایی طیفِ کاربران اولیه است. مسئله ی مطرح شده د...
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