Radio over Fibre Transport of Alamouti-coded MIMO Signals with Self-Recovery Capability

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Jaswinder Kaur ◽  
Vishal Sharma
Keyword(s):  
Spectral Efficiency ◽  
High Speed ◽  
Multipath Fading ◽  
Block Code ◽  
Wireless Channel ◽  
Modulation Scheme ◽  
Wireless Data ◽  
Wireless System ◽  
Radio Over Fibre ◽  
The Impact

AbstractRadio over Fibre (RoF) transport of high-speed wireless data provides a comprehensive solution for the forthcoming highly-reliable and spectral-efficient wireless systems. MIMO is one of the most widely used wireless technologies to increase the system reliability and capacity without any increased demand of power/bandwidth. However, the inherent non-linearities of RoF link and the multipath fading of the wireless channel can degrade the overall performance of the wireless system. In this work, authors demonstrate RoF transport of adaptively modulated MIMO signals and report the improvement in spectral efficiency under the impact of RoF link non-linearity. The transmitter of the proposed RoF based wireless system selects the appropriate modulation scheme with the assumption of perfect channel state information to achieve the acceptable BER at the subscriber end. The spectral efficiency improvement by this self-recovering MIMO-RoF system is evaluated by incorporating orthogonal Space-Time Block Code with 2 × 2 antenna configuration over the frequency-selective Rayleigh fading channel.

scholarly journals COMPARATIVE ANALYSIS OF MODULATION SCHEMES USING ADAPTIVE EQUALIZATION AS FADING MITIGATION TECHNIQUE

2012 ◽  
pp. 25-31
Author(s):  
SABITA NAHATA ◽  
SUBRATA BHATTACHARYA
Keyword(s):  
Comparative Analysis ◽  
Data Transmission ◽  
High Speed ◽  
Signal To Noise Ratio ◽  
Multipath Fading ◽  
Symbol Error Rate ◽  
Adaptive Equalization ◽  
Modulation Scheme ◽  
Modulation Schemes ◽  
Mitigation Technique

Inter-symbol interference (ISI) due to multipath fading is a vital problem in high-speed wireless communication which restricts communication quality and capacity. Therefore, in addition to choosing a fading mitigation technique, it is also important to strategically select a modulation scheme for effective data transmission. Recent literature review on wireless standards, such as 3G and 4G indicates that QAM and QPSK are suitable choices for data transmission. In this paper, a comparative analysis on selected modulation schemes is performed in a fading environment. The mitigation of fading is done using adaptive equalization technique. Also, we show that the signal to noise ratio (SNR) is an important parameter to choose. It is observed that, even when an adaptive equalizer is used at the receiver, a very low SNR gives very high symbol error rate (SER). We derive some important conclusions from our simulation result: QPSK shows minimum SER, whereas 256-PSK and 256-PAM perform worse. Given its spectral efficiency and a low SER, the best choice is 256- QAM.

Adaptive Transmission of Multimedia Data over UMTS

2007 ◽  
pp. 20-24
Author(s):  
A. Alexiou
Keyword(s):  
High Speed ◽  
Limited Resource ◽  
Mobile User ◽  
Wireless Channel ◽  
Multimedia Data ◽  
The Internet ◽  
Wireless Data ◽  
Multimedia Services ◽  
Internet Applications ◽  
Universal Mobile Telecommunications System

As communications technology is being developed, users’ demand for multimedia services raises. Meanwhile, the Internet has enjoyed tremendous growth in recent years. Consequently, there is a great interest in using the IP-based networks to provide multimedia services. One of the most important areas in which the issues are being debated is the development of standards for the universal mobile telecommunications system (UMTS). UMTS constitutes the third generation of cellular wireless networks which aims to provide high-speed data access along with real-time voice calls. Wireless data is one of the major boosters of wireless communications and one of the main motivations of the next-generation standards. Bandwidth is a valuable and limited resource for UMTS and every wireless network in general. Therefore, it is of extreme importance to exploit this resource in the most efficient way. Consequently, when a user experiences a streaming video, there should be enough bandwidth available at any time for any other application that the mobile user might need. In addition, when two different applications run together, the network should guarantee that there is no possibility for any of the above-mentioned applications to prevail against the other by taking all the available channel bandwidth. Since Internet applications adopt mainly TCP as the transport protocol, while streaming applications mainly use RTP, the network should guarantee that RTP does not prevail against the TCP traffic. This means that there should be enough bandwidth available in the wireless channel for the Internet applications to run properly.

scholarly journals PAPR reduction in OFDM system for DVB-S2

2020 ◽  
Vol 17 (1) ◽  
pp. 317
Author(s):  
Zainab M Abid ◽  
Awatif A Jaffaar ◽  
Suha Q Hadi
Keyword(s):  
Fading Channels ◽  
Power Amplifier ◽  
Spectral Efficiency ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Average Power ◽  
Multipath Fading ◽  
Papr Reduction ◽  
Major Drawback ◽  
Ofdm Signal

<p>A special form of multicarrier modulation is Orthogonal Frequency Division Multiplexing (OFDM) which is offer high spectral efficiency for high speed data transmission through multipath fading channels. Many advantages can be achieved by using OFDM in addition to spectral efficiency like its robustness against intersymbol interference and multipath effect. One of a major drawback of OFDM is high Peak-to-Average Power Ratio (PAPR) of the transmitted signal which leads to a distortion in the power amplifier and causes decreasing the efficiency of power amplifier. To reduce PAPR of OFDM signal many of promising solutions have been proposed and implemented. In this paper, a joint Low Density Parity Check code (LDPC), Discrete Cosine Transform (DCT) and μ-law companding is proposed to reduce PAPR of OFDM signal at transmitter. Comparison of these PAPR reduction techniques is done based on CCDF performance of the system.</p>

scholarly journals Study on Predistortion Techniques and Adaptive Modulation Used in Fading Channels

2013 ◽  
Vol 756-759 ◽  
pp. 3723-3727
Author(s):  
Wei Liu ◽  
E Zhang
Keyword(s):  
Fading Channels ◽  
Spectral Efficiency ◽  
Adaptive System ◽  
Adaptive Modulation ◽  
Modulation Scheme ◽  
Primary Concern ◽  
Propagation Channel ◽  
Wireless Data ◽  
Mobile Channels ◽  
Linear And Nonlinear

Spectral efficiency is one of primary concern in the design of any wireless data communications systems, where fading is the main problem. An approach that can be taken to overcome the problem of fading is to adapt the modulation scheme according to the instantaneous propagation channel conditions. In this paper, we present a simplified mathematical model to calculate the probability of SER for any given constellation of M-QAM. This model plays an important role in designing spectrally efficient adaptive modulation over nonlinear mobile channels. Instantaneous spectral efficiency and its histogram distribution are found for linear and nonlinear channel cases. The achievable spectral efficiency is obtained for linear and nonlinear channel and compared with non-adaptive system and Shannon capacity.

scholarly journals BER Performance of Stratified ACO-OFDM for Optical Wireless Communications over Multipath Channel

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Zelalem Hailu Gebeyehu ◽  
Philip Kibet Langat ◽  
Ciira Wa Maina
Keyword(s):  
Wireless Communications ◽  
Spectral Efficiency ◽  
High Speed ◽  
Multipath Fading ◽  
Ofdm Systems ◽  
Optical Wireless ◽  
Optical Wireless Communications ◽  
Efficiency Loss ◽  
Optical Ofdm ◽  
Ber Performance

In intensity modulation/direct detection- (IM/DD-) based optical OFDM systems, the requirement of the input signal to be real and positive unipolar imposes a reduction of system performances. Among previously proposed unipolar optical OFDM schemes for optical wireless communications (OWC), asymmetrically clipped optical OFDM (ACO-OFDM) and direct current biased optical OFDM (DCO-OFDM) are the most accepted ones. But those proposed schemes experience either spectral efficiency loss or energy efficiency loss which is a big challenge to realize high speed OWC. To improve the spectral and energy efficiencies, we previously proposed a multistratum-based stratified asymmetrically clipped optical OFDM (STACO-OFDM), and its performance was analyzed for AWGN channel. STACO-OFDM utilizes even subcarriers on the first stratum and odd subcarriers on the rest of strata to transmit multiple ACO-OFDM frames simultaneously. STACO-OFDM provides equal spectral efficiency as DCO-OFDM and better spectral efficiency compared to ACO-OFDM. In this paper, we analyze the BER performance of STACO-OFDM under the effect of multipath fading. The theoretical bit error rate (BER) bound is derived and compared with the simulation results, and good agreement is achieved. Moreover, STACO-OFDM shows better BER performance compared to ACO-OFDM and DCO-OFDM.

scholarly journals Space-Time Block Coded Spatial Modulation Based on Golden Code

2018 ◽  
Author(s):  
Tien Dong Nguyen ◽  
Xuan Nam Tran ◽  
Vu Duc Ngo ◽  
Minh Tuan Le
Keyword(s):  
Spectral Efficiency ◽  
Block Code ◽  
Space Time ◽  
Spatial Modulation ◽  
Time Block ◽  
Space Time Block Code ◽  
New Space ◽  
Golden Code ◽  
The Impact ◽  
Theoretical Results

In this paper, a new Space-Time Block Coded Spatial Modulation (SM) scheme based on the Golden Code, called the Golden Coded Spatial Modulation (GC-SM), is proposed and analyzed. This scheme still keeps some main benefits of the Golden Code by satisfying the non-vanishing Space Time Block Code (STBC) criteria. In the signal constellation domain, the GC-SM spectral efficiency is twice that of the STBC-SM. In addition, simulation and theoretical results show that the GC-SM performance surpasses several SM schemes at the same spectral efficiency and antenna configuration. Furthermore, we study the impact of channel spatial correlation on the GC-SM performance. Finally, the GC-SM detection complexity is studied and compared with the existing SM schemes. DOI: 10.32913/rd-ict.vol2.no15.702

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

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