Spectral Efficiency Optimization in Flexi-Grid Long-Haul Optical Systems

Flexible grid optical networks allow a better exploitation of fiber capacity, by enabling a denser frequency allocation. A tighter channel spacing, however, requires narrower filters, which increase linear intersymbol interference (ISI), and may dramatically reduce system reach. Commercial coherent receivers are based on symbol by symbol detectors, which are quite sensitive to ISI. In this context, Nyquist spacing is considered as the ultimate limit to wavelength-division multiplexing (WDM) packing. In this paper, we show that by introducing a limited-complexity trellis processing at the receiver, either the reach of Nyquist WDM flexi-grid networks can be significantly extended, or a denser-than-Nyquist channel packing (i.e., a higher spectral efficiency (SE)) is possible at equal reach. By adopting well-known information-theoretic techniques, we design a limited-complexity trellis processing and quantify its SE gain in flexi-grid architectures where wavelength selective switches over a frequency grid of 12.5GHz are employed.Comment: 7 pages, 9 figure

Building up low-complexity spectrally-efficient Terabit superchannels by receiver-side duobinary shaping

Recently, an increasing interest has been put on spectrally-efficient multi-carrier superchannels for beyond 100G. Apart from orthogonal frequency-division multiplexing (OFDM) and Nyquist wavelength-division multiplexing (WDM), another low-complexity WDM approach based on transmitter-side pre-filtering and receiver-side duobinary shaping is proposed to build up multi-carrier superchannels. This approach is referred to as receiver-side duobinary-shaped WDM (RS-DBS-WDM). Generation and transmission of a 1.232-Tbit/s 11-carrier superchannel is experimentally demonstrated. The superchannel signal can be well fit inside the passband of multiple 300-GHz reconfigurable optical add and drop multiplexers (ROADMs). In the superchannel scenario, the proposed RS-DBS-WDM is qualitatively compared with OFDM and Nyquist-WDM in terms of implementation complexity. In sum, the proposed RS-DBS-WDM approach features high transceiver analog-bandwidth efficiency, high spectral-efficiency, the absence of specific spectral manipulation, compatibility with conventional WDM technologies and coherent detection algorithms, and comparable implementation penalty

Comparative Analysis of Bit Error Rate and Outage Capacity for MIMO Space Time Trellis Coding

In this paper, we have first given brief introduction to Multiple Inputs Multiple Outputs (MIMO) systems. After that different MIMO models and their capacity is discussed. We have compared bit error rate of different modulation techniques like Phase Shift Keying (PSK), Quadrature Amplitude Modulation i.e. QAM 16, QAM 32, QAM 64 using Space Time Trellis Coding (STTC). The outage capacity and bit error rate of MIMO and MISO have also been compared. The Rank criterion is used for maximizing the rank of transmitting antennas matrix in STTC. The proposed technique increases spatial diversity and coding gain of MIMO channels

Multidimensional Index Modulation for 5G and Beyond Wireless Networks

This study examines the flexible utilization of existing IM techniques in a comprehensive manner to satisfy the challenging and diverse requirements of 5G and beyond services. After spatial modulation (SM), which transmits information bits through antenna indices, application of IM to orthogonal frequency division multiplexing (OFDM) subcarriers has opened the door for the extension of IM into different dimensions, such as radio frequency (RF) mirrors, time slots, codes, and dispersion matrices. Recent studies have introduced the concept of multidimensional IM by various combinations of one-dimensional IM techniques to provide higher spectral efficiency (SE) and better bit error rate (BER) performance at the expense of higher transmitter (Tx) and receiver (Rx) complexity. Despite the ongoing research on the design of new IM techniques and their implementation challenges, proper use of the available IM techniques to address different requirements of 5G and beyond networks is an open research area in the literature. For this reason, we first provide the dimensional-based categorization of available IM domains and review the existing IM types regarding this categorization. Then, we develop a framework that investigates the efficient utilization of these techniques and establishes a link between the IM schemes and 5G services, namely enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable low-latency communication (URLLC). Additionally, this work defines key performance indicators (KPIs) to quantify the advantages and disadvantages of IM techniques in time, frequency, space, and code dimensions. Finally, future recommendations are given regarding the design of flexible IM-based communication systems for 5G and beyond wireless networks.Comment: This work has been submitted to Proceedings of the IEEE for possible publicatio

High Data Rate Wireless Communication Using MIMO

Wireless communication is the most popular and rapidly growing sector of the commu-nication industry. The permitted bandwidth for every service is very limited and the demand of data transferring is increasing day by day. Moreover, the channels are further limited by multipath and fading. Hence, it is a big challenge to provide excellent quality of service and meet the growing demand with the existing bandwidth limitation. MIMO is one very promising technique to enhance the data rate. Fading has been considered as problem for high quality with low outage wireless com-munication. However, multiple-input multiple-output (MIMO) antenna has used this fading phenomenon not only to mitigate the fading but also to exploit this fading to obtain high data rate through spatial multiplexing. In this thesis, MIMO spatial multiplexing has been studied in details. Different MIMO channel models, space time coding, and channel capacity constraints as well as the fac-tors those limits the capacity are studied. One major aim of this study is to find a com-bined optimal solution for MIMO system so that it could provide high rate data transfer.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format