Investigation of modulation format conversion for optical channel deaggregation in elastic optical network

To adapt to the network dynamics and support elastic network resource allocation in the future elastic optical networks, optical transmitter with flexibility and re-configurability in modulation formats becomes indispensable, offering network providers flexibility in transport bandwidth. In this paper, we discuss our proposed two flexible high-order quadrature amplitude modulation (QAM) transmitter schemes, including (i) a flexible transmitter based on tandem in-phase/quadrature (IQ) modulators for generating 16QAM, 32QAM, 64QAM signals; and (ii) a scheme based on monolithically-integrated quad-Mach-Zehnder IQ modulator (QMZ-IQ) with binary driving electronics for synthesizing minimum phase-shift keying (MSK), quadrature phase-shift-keying (QPSK), 8-ary phase-shift keying (8PSK), and 16QAM signals. These schemes provide different approaches to configure a flexible high-order QAM transmitter, either using cascaded off-the-shelf modulators, or via highly-integrated monolithic modulator. These flexible and reconfigurable transmitter schemes provide the network providers different flexible transmitter solutions suitable for different application scenarios in elastic optical networks.

Background/Objectives: Tremendous growth in the mobile communication services in this technology driven era has made possible for the people to exchange information (data, voice or image) with each other while they are on the move. These wireless systems have brought a revolution in the current market for their high data rates and performance enhanced features. Methods/Statistical Analysis: One of the key issues affecting the performance of a wireless channel is the random variations in the signal strength which may be resulted due to some obstructions like buildings, trees, etc. or due to the movement of the mobile user. This leads to stochastic behavior of the radio channel.. A highly faded Two-Wave with Diffuse Power (TWDP) environment is discussed along with hybrid diversity combining technique. The effectiveness of this scheme is further evaluated by analyzing the system performance in terms of Bit Error Rate (BER) vs Signal to Noise Ratio (SNR). Binary Phase Shift Keying (BPSK) and Quadrature Phase Shift Keying (QPSK) modulation techniques were employed. Findings: It has been shown clearly that TWDP forms the poorer link when compared with other fading channels as BER is higher in this case. Moreover, TWDP fading environment can serve as the worst case scenario in wireless communication system. Also it has been shown as the diversity order increases system’s performance is improved in terms of BER and reduction in SNR requirement to achieve a constant BER value. Application/Improvement: This paper presents the need to obtain a clear perception of channel characteristics and to model a system for combating fading and improving the system performance by considering a TWDP fading channel instead of Rayleigh channel while designing a wireless communication system in worst channel conditions..

The WiMax (Worldwide Interoperability for Microwave Access) is a technology in<strong> </strong>broadband wireless access, which employs OFDM (Orthogonal Frequency Division Multiplexing) as an alternative transmission to enable high speed data in communication system. This research aim is to analyze the performance system of the OFDM-Based WiMAX, which used the cyclic prefix. The model was designed in four schemes of simulation method, the BPSK (Binary Phase Shift Keying, QPSK (Quadrature Phase Shift Keying), 16 QAM (Quadrature Amplitude Modulation) and 64 QAM. Each scheme was investigated BER (Bit Error Rate) on AWGN (Additive White Gaussian Noise) channel and multipath Rayleigh fading channel, which had applied the cyclic prefix. By simulation of the cyclic prefix was produced the modulation measurement of the BPSK, QPSK, 16 and 64 QAM. The performance result of Eb/No 15 dB was obtained the BER of BPSK and QPSK of 1.11E-11, the BER of 16 QAM and 64 QAM of 8.69E-06 and 0.00333 respectively. Those results indicated much smaller BER value than EbNo 0 dB which BPSK and QPSK of 1 BER, 1.5 and 1.75 BER for 16 QAM and 64 QAM respectively. In conclusion, a higher value of EbNo, hence the BER value would be lower.

Low voltage, in-home power-line communications (PLC) networks allow direct communication between smart meters (SM) and in-home devices (IHD). In order to minimize security issues, in many deployment scenarios transmission takes place only towards the IHD to display consumption data, with no backwards channel. As a result, channel estimation is difficult and it is necessary to use robust transmission techniques to mitigate the effect of the impulsive noise within the PLC channel. Performance of such system must be evaluated by taking into account realistic interference and channel models for a broad range of configurations. In this work we focus on performance in terms of bit error rate (BER) of a narrowband PLC (NB-PLC) operating in the CENELEC-C band (125–140 kHz) taking into account realistic noise models. Our system is based on binary phase shift keying (BPSK) and quadrature phase shift keying (QPSK) modulation.

In this chapter, a successful attempt for transmission of secured compressed data over GSM voice channel has been made. In this work, given text of any length is converted to real-time speech signal and then compressed with discrete wavelet transform, encoded with gold code sequence, modulated using quadrature phase-shift keying and sent over the GSM voice channel. The aim of this paper was to present a secured digital data compression and modulation for robust data transmission in terms of voice. The main objective was to achieve higher data rates, lower bit error rate, and less utilization of the bandwidth. The performance of the proposed technique is compared to an already existing technique for data transmission over voice channel. It has been observed that the proposed technique shows much better results in terms of bit error rate (BER), mean square error (MSE), and peak signal-to-noise ratio (PSNR) as compared to the already existing techniques. The proposed scheme has a great significance in GSM systems where data security and quality of service (QoS) are two main issues.

An underwater acoustic multimedia communication (UWAMC) system is proposed with 2400 transmission modes according to time-varying multipath underwater acoustic (UWA) channel conditions. The orthogonal variable spreading factor (OVSF) scheme and Gold sequence (GS) scramble code are integrated into multi-input multi-output UWAMC system based on orthogonal frequency-division multiplexing to achieve the quality of service of multimedia transmission in the UWA channel. Binary phase shift keying (BPSK) and quadrature phase shift keying (QPSK) adaptive modulation, direct mapping (DM) or space–time block code (STBC) transmission strategies, convolution channel code with rate 1/2 and 1/3, and a power assignment mechanism were adopted in the proposed system. Simulation results show that the bit error rate (BER) and power saving ratio (PSR) performance of the STBC strategy with transmission diversity is superior to that of the DM strategy without transmission diversity, and the performance of the BERs and PSRs of the transmission scheme with the GS scramble code surpasses that of the scheme without the code. The performance of the BERs and PSRs of BPSK modulation with a channel code rate of 1/3 is better than that of BPSK modulation with a channel code rate of 1/2, and the performances of BERs and PSRs of BPSK modulation with a channel code rate of 1/3 are better than that of QPSK modulation with a channel code rate of 1/3. As the length of the OVSF codes increases, the UWAMC system’s BERs decrease, and its PSRs increase. The UWAMC system can achieve either maximum transmission speed or maximum transmission power efficiency.

This paper presents three 4-level optical modulation formats; two of which are intensity modulation formats - the 4-pulse amplitude modulation (4-PAM) and the absolute added correlative coding (AACC); and one coherent modulation format - the quadrature phase shift keying (QPSK); in a laser inter-satellite link (LISL), respectively. Each modulated link is modelled to operate in a low Earth orbit (LEO) satellite broadband constellation network and simulated for various performance parameters. These parameters include the power-efficiency, link-extendibility, receiver-sensitivity and spectral-efficiency of the modelled links. As all three modulated LISLs share a spectral-efficiency, the 4-PAM is observed to need a minimum transmitter laser power of 32 dBm to support a bit rate of 20 Gbps at the maximum LEO LISL distance of 6000 km. The AACC and QPSK required 28 dBm. Keeping to a bit-error rate (BER) of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−9</sup> and a constant transmitter power of 30 dBm, the AACC and QPSK sustains the maximum LEO LISL distance whereas the 4-PAM supports a link distance of 4000 km. The AACC modulated LISL also observed an improvement of ~ 7 dBm in receiver-sensitivity over the 4-PAM. All three modulated LISLs are then simulated for a bit rate of 40 Gbps. The 4-PAM and QPSK were found to support a link distance of 3000 km and 5000 km, respectively, whilst the AACC sustains up to a distance of 6000 km.

In this paper, a scheme for optical modulation format conversion from one 20Gbps quadrature phase-shift keying (QPSK) signal to one 20Gbps binary phase-shift keying (BPSK) signal with information integrity is proposed and verified by simulation. The theory of degenerate phase-sensitive amplifier (PSA) employed as a phase de-multiplexer is derived in detail and used to decompose the in- (I) and quadrature- (Q) phase components of QPSK. Then the I and Q components are parallel-to-series converted into one BPSK. The constellations show that the phase noise of the original signal is effectively restrained by the conversion system through use of the PSA. The error vector magnitude and bit-error rate (BER) of the QPSK, converted BPSK, and a back-to-back BPSK are measured and compared with each other. We find that the BER performance of the converted BPSK is better than QPSK and maintains the original information integrity with different input signal quality. Some potential issues are also discussed as to practical implementation of the scheme. This modulation-format-conversion scheme has potential applications in improving the signal BER performance and flexible transmitters and receivers in software-defined networks.

Hybrid code division multiple access (CDMA) scheme utilizes advantages of both direct sequence spread spectrum (DS/SS) and frequency hopped spread spectrum (FH/SS) systems, while overcoming some of their shortcomings. To enhance performance of this hybrid system, an efficient modulation scheme must be used that can perform favorably in a fading environment. We have compared the bit error rate (BER) performance of two spectrally efficient schemes namely, quadrature phase shift keying (QPSK) and minimum phase shift keying (MSK), when used in a hybrid system, over a Rayleigh fading channel. Simulation results show that hybrid MSK indeed is a better scheme in a multi-user (CDMA) environment in that, it achieves lower BER than hybrid QPSK. The comparison has been extended by including a predetection diversity reception scheme. >

Elastic optical networking (EON) equipped with multiple modulation formats has recently emerged as a promising solution to flexible provisioning in optical networks. To overcome the limit of high-order modulation formats for long distance transmission, traffic can be split and carried by multiple channels, with each modulated at lower rates. However, the flexibility offered by EON and its multi-channel variant comes with a higher cost for extra hardware components (e.g., laser and modulator array). This paper studies the single- and multi- channel EON schemes from a cost effectiveness point of view, with comparison to the conventional 40/100G provisioning scheme based on the ITU-T grid. We first propose and discuss the hardware module implementation of the EON schemes. By decomposing the hardware module into mechanics and electrical, analog/digital conversion, and optics, we propose cost models for each part based on current and historical market data. Two key metrics, hardware cost and traffic-share cost, are calculated and analyzed. We show that the hardware cost based on the proposed model well matches the market trend. Also, the result indicates that the two EON schemes, though are more expensive due to hardware complexity, can effectively reduce the traffic-share cost according to our simulation of a network-wide provisioning scenario. In particular, the multi-channel EON can reduce the traffic-share cost by up to 21.1% from the single-channel EON in the investigated scenarios, achieving the highest cost effectiveness among the three schemes.

In this letter, we consider an $N_{r} \times N_{t}$ multiple-input–multiple-output system in which $M$ -ary phase shift keying (MPSK) and space shift keying (SSK) are used in successive time slots. We call this system time successive SSK-MPSK (TSSM), and we show that this system achieves a transmit diversity order of 2. In TSSM, during the first time slot, information is transmitted with MPSK symbols using all $N_t$ transmitter antennas, with each antenna using $N_{t}^{\textrm{th}}$ of the total transmitter power. During the second time slot, SSK modulation is used to transmit the same information. We further derive the optimal detection criterion, pairwise error probability, and the average union bound of the bit error rate (BER) of TSSM. We show the diversity order using asymptotic approximation of the average union bound of the BER of TSSM. We compare the BER of TSSM with that of time orthogonal signal design assisted SSK, coherent space time shift keying, and other schemes. The simulation results show that TSSM performs considerably better.

The 4G up-gradation was essential because of the exponential increment of the wireless applications. So, 5G was introduced with large capacity, small latency, improved reliability, high data rate, and better quality of services (QoS). 4G uses orthogonal frequency-division multiplexing (OFDM) which has a decent quality of long-distance communication, by eliminating intersymbol interference (ISI) and improving the signal-to-noise ratio (SNR), but it has a spectrum wastage problem. However, the improved data rate is possible by spectrum utilization. 5G adopted various techniques for the better utilization of spectrum in current scenarios. The new generation waveforms, i.e., filtered orthogonal frequency-division multiplexing (F-OFDM), generalized frequency-division multiplexing (GFDM), universal filtered multicarrier (UFMC), and filter bank multicarrier (FBMC), are one of them. This paper will discuss FBMC which is the alternative technology of OFDM with better features by building subcarrier waveform based on prototype filters. Here, FBMC is investigated in terms of BER (bit error rate) by varying several parameters such as the size of inverse fast Fourier transforms/fast Fourier transform (IFFT/FFT), length of guard band, and length of symbols. Results of simulation will show that the bit error rate (BER) of FBMC is not affected by the variation of symbol length, while advancement in the size of IFFT/FFT increases BER, on the given parameter while the BER reduces for large size of the guard band of each subcarrier.KeywordsFilter Bank MulticarrierIFFT/FFTOffset QAMOrthogonal Frequency-Division MultiplexingBit Error Rate

The Multi user Multi Carrier Direct sequencing Code Division Multiple Access (MU-MC-DS-CDMA) strategy was developed in response to rising demand for system capacity, higher data rates, and multimedia services. It's essentially a combination of CDMA and OFDM schemes. As a result, MC-CDMA takes the advantages of both CDMA and OFDM technologies. CDMA improves bandwidth consumption performance, whereas OFDM helps to minimize Inter Symbol Interference (ISI) and multipath fading. This dissertation suggests a method for evaluating the performance of multi user MC-DS-CDMA system. BER and PAPR are used to evaluate the results. The Bit Error Rate (BER) output of the proposed method is then examined using MATLAB for various modulation techniques. By using Walsh-Hadamard (W-H) code is used because it eliminates Multiple Access Interference (MAI). In terms of BER, it can be shown that BPSK performs better than QPSK. Key Words: AWGN, BER, ISI, MC-CDMA, Rayleigh Fading Channel, SNR, QPSK, MAI

Performance of both orthogonal frequency division multiplexing (OFDM) and single carrier (SC) systems suffers from a carrier frequency offset (CFO) due to Doppler effect and the carrier instability between the transmitter and the receiver. We investigate the bit error rate (BER) performance degradation of OFDM and SC systems due to the frequency offset in an additive white Gaussian noise (AWGN) channel as well as multipath Rayleigh fading channels. We consider three effects to the BER degradation, i.e., phase shift, useful power decrease and intercarrier interference (ICI). We also derive the approximate expressions of BER under binary phase shift keying (BPSK) and quaternary phase shift keying (QPSK) for both OFDM and SC systems in the presence of CFO. In general, SC is more robust to CFO in the AVVGN channel than OFDM in terms of BER, while both of them suffer similarly from CFO in the multipath Rayleigh fading channels assuming the the same CFO.

The emerging trends of wireless communication and ever growing demand of very high data rate from users created the need for new technologies that could satisfy this need under limited bandwidth. A 60-GHz Ultra-Wideband (UWB) system that can support up to 7 Gbps data rate, which is 10 times faster than the data rate of the Wi-Fi 802.11n, is one of the promising options. The system utilizes higher order modulation and advanced coding schemes known as Adaptive Modulation and Coding (AMC). However, inappropriate selection of modulation level and coding rate can lead to low data rate particularly in the presence of Radio Frequency interference and multipath fading. Moreover, further performance degradation occurs when non-optimal decoder due to code constraint length was selected. This paper proposes and evaluates a duplex 60-GHz UWB system employing Orthogonal Frequency Division Multiplexing (OFDM-UWB) to boost the data rate and extend the coverage. Firstly, an OFDM-UWB system employing high order modulation that transmits data simultaneously over multiple carriers spaced apart at precise frequencies been simulated and validated using Matlab. Secondly, the system performance been analyzed when convolutional coding been introduced in term of Bit Error Rate (BER). The simulation results show that the BER performance of 16QAM is worse, with 6 dB penalties at BER of 10−3, compared with that of QPSK. Moreover, simulation also shows that there are 2 dB difference between the performance of R=1/2 and R=7/8, while the highest throughput been achieved when the 3/4 code rate is employed.