نتایج جستجو برای: multipath fading channel
تعداد نتایج: 240253 فیلتر نتایج به سال:
Channel estimation techniques for code-division multiple access (CDMA) systems need to combat multiple access interference (MAI) effectively. Most existing estimation techniques are designed for CDMA systems with short repetitive spreading codes. However, current and next-generation wireless systems use long spreading codes whose periods are much larger than the symbol duration. In this paper, ...
3G mobile communications is advanced and emerging technology in the field of wireless communication also providing facilities like multimedia accessing, internet services, higher capacity of data rates and multiple services for same connection. The Rake receiver involves descrambling, dispreading, channel estimation and fading cancellation. The main principle behind Rake receiver is that they e...
This paper analyses the reverse link capacity of a SIR-based power-controlled code-division multiple access (CDMA) system in a multiple-cell environment where the radio channel is affected by multipath Rayleigh fading. Unlike most previous works related to SIR-based power control, the effect of multipath fading is explicitly accounted for and mobiles are assumed to connect to the base station w...
Orthogonal Frequency Division Multiplexing (OFDM) is a special form of multicarrier modulation scheme, which divides the entire frequency selective fading channel into many orthogonal narrow band flat fading sub channels. Orthogonal Frequency Division Multiplexing (OFDM) is considered to be a promising technique against the multipath fading channel for wireless communications [1]. However, OFDM...
Successive interference cancellation is a promising technique for increasing the capacity of uplink CDMA channels. In this paper, the technique is extended to a low-earth orbit satellite channel. Unlike terrestrial cellular channels, satellite channels typically have a limited multipath profile, but significant closed-loop power control error due to the round-trip delay incurred in communicatin...
OFDM renders multipath channels with nite memory equivalent to parallel at fading subchannels, over which equalization amounts to simple phase compensation. If the channel status information is known at the transmitter side, optimal power loading across subchannels is possible. Users mobility, time and carrier asynchronism introduce variations in the equivalent channel impulse response setting ...
The widespread applications of Mobile Ad hoc Networks (MANETs) have lead to the development of many protocols in this field. Routing protocols for ad hoc networks have generally ignored channel fading. This paper proposes a routing protocol which calculates the channels non-fading duration for routing which attempts to minimize packet loss due to fading and also reuse the path with some securit...
Due to multipath fading and inter-symbol interference, the high speed transmitted data extends to several symbol periods. Signals which travel through several paths get reflected by different objects and signals taking less direct path arrive at receiver later and are often attenuated. Traditional systems employ some improvement techniques to deal with multipath signals; one technique is to use...
An effort has been made to illustrate the performance of the Rayleigh fading channel models by using Qual net simulator in terms of Throughput and PDR. A scenario has developed here for the Rayleigh fading channels, with various parameter. The parameters such as data rate and speed of nodes play very important role in the performance analysis and design of the mobile ad-hoc network over the mul...
An eecient series that is used to calculate the probability of error for a BPSK modulated DS CDMA system with chip timing and carrier phase errors in a slowly fading, multipath channel is derived. The receiver is assumed to be a coherent RAKE receiver that employs selection diversity. The error probability derivations require the characteristic functions of the intersymbol interference and the ...
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