Dispersion code modulation for enhanced spectral efficiency in wireless communications

2016 ◽  
Author(s):  
Lianfeng Zou ◽  
Shulabh Gupta ◽  
Christophe Caloz
Keyword(s):  
Wireless Communications ◽  
Spectral Efficiency ◽  
Code Modulation

scholarly journals Medium access control protocol design for wireless communications and networks review

2022 ◽  
Vol 12 (2) ◽  
pp. 1711
Author(s):  
Zaid Hashim Jaber ◽  
Dheyaa Jasim Kadhim ◽  
Ahmed Sabah Al-Araji
Keyword(s):  
Wireless Networks ◽  
Wireless Communications ◽  
Access Control ◽  
Medium Access Control ◽  
Spectral Efficiency ◽  
Research Method ◽  
Multiple Access ◽  
Mac Protocol ◽  
Protocol Design ◽  
Medium Access

<p><span>Medium access control (MAC) protocol design plays a crucial role to increase the performance of wireless communications and networks. The channel access mechanism is provided by MAC layer to share the medium by multiple stations. Different types of wireless networks have different design requirements such as throughput, delay, power consumption, fairness, reliability, and network density, therefore, MAC protocol for these networks must satisfy their requirements. In this work, we proposed two multiplexing methods for modern wireless networks: Massive multiple-input-multiple-output (MIMO) and power domain non-orthogonal multiple access (PD-NOMA). The first research method namely Massive MIMO uses a massive number of antenna elements to improve both spectral efficiency and energy efficiency. On the other hand, the second research method (PD-NOMA) allows multiple non-orthogonal signals to share the same orthogonal resources by allocating different power level for each station. PD-NOMA has a better spectral efficiency over the orthogonal multiple access methods. A review of previous works regarding the MAC design for different wireless networks is classified based on different categories. The main contribution of this research work is to show the importance of the MAC design with added optimal functionalities to improve the spectral and energy efficiencies of the wireless networks.</span></p>

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 Evaluation of 5G Modulation Candidates WCP-COQAM, GFDM-OQAM, and FBMC-OQAM in Low-Band Highly Dispersive Wireless Channels

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Aitor Lizeaga ◽  
Pedro M. Rodríguez ◽  
Iñaki Val ◽  
Mikel Mendicute
Keyword(s):  
Cognitive Radio ◽  
Wireless Communications ◽  
Mobile Communications ◽  
Spectral Efficiency ◽  
Wireless Channels ◽  
Multipath Channels ◽  
Low Latency ◽  
Power Spectral ◽  
Industrial Communications ◽  
Indoor Spaces

We analyse some of the candidates for modulations for 5G: FBMC-OQAM, GFDM-OQAM, and WCP-COQAM. Unlike most of the related bibliographies, which are oriented to mobile communications, our research is focused on 5G in cognitive radio based industrial wireless communications. According to the ultrareliability and low-latency requirements of industrial communications, we simulate the aforementioned modulations in low-band transmissions (carrier frequencies below 6 GHz and a bandwidth narrower than 100 MHz) through large indoor spaces and severe multipath channels that emulate industrial halls. Moreover, we give detailed information about WCP-COQAM and how the windowing affects the protection against multipath effect and reduces spectral efficiency compared to GFDM-OQAM. We also compare the aforementioned filtered multicarrier techniques and OFDM in terms of robustness against multipath channels, power spectral density, and spectral efficiency. Based on these results, we aim at providing an approximate idea about the suitability of 5G MCM candidates for industrial wireless communications based on CR.

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