نتایج جستجو برای: adaptive modulation
تعداد نتایج: 344707 فیلتر نتایج به سال:
Abstract—In wireless systems supporting slowly moving users, adaptive trellis-coded modulation (TCM) schemes have demonstrated large bandwidth efficiency gains over their nonadaptive counterparts. In systems with highly mobile users, the recently proposed adaptive bit-interleaved coded modulation (BICM) achieves a moderate bandwidth efficiency gain over previously proposed adaptive schemes and ...
Channel estimation at the receiver is essential for Variable Rate (adaptive) modulation schemes and this prohibits systems that are less complex from using (adaptive) variable rate and/or variable power transmissions. Providing a solution to this problem, we introduce a variable-rate (VR) M-PSK modulation scheme, for communications over fading channels, without channel gain estimation at the re...
Software defined radio (SDR) is the future trend for mobile communication. A SDR is supposed to facilitate high speed multimedia application for future mobile standards. Adaptive modulation forms an integral part of SDR system with robust and high data rate capability. Here we have analyzed adaptive modulation scheme with their performance in changing channel condition. The modulation scheme st...
شبکه های نسل آینده مخابرات سیار به سیستمهایی نیازمندند که قابلیت پشتیبانی از سرویسهای مختلف با محدوده گسترده ای از نرخ داده را دارا باشند. رشد تقاضا برای انواع سرویسهای بدون سیم به تلاش در راستای افزایش تعداد کاربران تحت پوشش، افزایش نرخ داده و تنوع نرخ انجامیده است. روشهای ارسال با نرخ وفقی که در انطباق با کانال اعمال می شوند، و روشهای چندگانگی از تکنولوژیهای کلیدی دستیابی به این مهم می باشند....
Adaptive Modulation and Coding technique has emerged as a bandwidth efficient transmission scheme. It is motivated by its ability to improve spectral efficiency by adapting the transmission rates to the variations in channel signal-to-noise ratio. The implementation of apt rate adaptation algorithms based on either signal to noise ratio or successful packet transmission has been the crucial fac...
Adaptive modulation is one of the recent technologies used to improve future communication systems. Many adaptive modulation techniques have been developed for the improving the performance of Orthogonal Frequency Division Multiplexing (OFDM) system in terms of high data rates and error free delivery of data. But uncertain nature of wireless channel reduces the performance of OFDM system with f...
In order to improve the video transmission performance in multiple input multiple output (MIMO) system, an unequal error protection (UEP) transmission scheme based on coded adaptive modulation is proposed in this paper. Specifically, the excess power which is wasted in normal adaptive modulation schemes is utilized to transmit important bits of the video source. Furthermore, a low density parit...
In this paper, introduced below are the concepts of digital modulation used in many communication systems today. Techniques described include quadrature phase shift keying (QPSK) and quadrature amplitude modulation (QAM) and how these techniques can be used to increase the capacity and speed of a wireless network. These modulation techniques are the basis of communications for systems like cabl...
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