For over 40-Gbps optical communication systems, phase coded modulation formats, like differential phase shift keying (DPSK) and quadrature phase shift keying (QPSK), are very important for signal frequency efficiency and long-reach transmission. In such systems, differential receivers which regenerate phase signals are key components. Dual Photo Diodes (dual PDs) are key semiconductor devices w...

The current work presents a study of the implementation quadrature chaos phase-shift keying communication system (QCPSK) based on employment different oscillators. research takes two directions, with one being synchronization’s noise immunity for several oscillators that are potential core blocks QCPSK system. correlation coefficient over time is used to estimate synchronization immunity. secon...

a direct-sequence signal with binary phase-shift keying (BPSK) or differential block diagram of direct-sequence systemn with BPSK or DPSK: a transmitter. Differential Phase Shift Keying. ▫ For a standard telephone circuit with S/N of 3000 (30. dB) and A block diagram of a QPSK modulator is shown in the next. differential phase shift keying (DPSK) modulations is that both Block diagram of the ge...

Power and cost efficient short-range optical links are one of the technologies enabling large scale high-performance computers and data centers. Such links typically use directly modulated vertical cavity surface emitting lasers, multi-mode fiber, direct detection and on-off keying (OOK) modulation. In this work replacement of OOK with multilevel modulation formats is studied, with possible app...

In this paper we evaluated the performance of orthogonal space-time block codes with transmit antenna selection (TAS/OSTBCs) for frequency-flat correlated Rayleigh fading channels. By effective use of the probability density function (pdf), the bit error probability (BEP) for binary phase shift keying (BPSK) and M-ary Quadrature amplitude modulation (M-QAM) is derived first. Further we evaluate...

We designed an optical add/drop multiplexer for orbital-angular-momentum (OAM)-multiplexed data links by taking advantage of the ring-shaped intensity profile of OAM beams. We demonstrated adding/dropping a single OAM beam from three multiplexed OAM beams using liquid-crystal-on-silicon-based diffraction optical elements. For multiplexed OAM beams carrying 100 Gbit/s quadrature phase-shift-keyi...

π/4-DQPSK (π/4-differential quadrature phase shift keying), the scheme using nonredundant multiple error correction is proposed and investigated. This scheme for the differential detection of π/4-DQPSK uses the signal output which is delayed for more than two time slots as the parity check bit and applies it to nonredundant multiple error correction. The proposed system was used for studying th...

† Contact author is Dr. K. Giridhar, Department of Electrical Engineering, IIT Madras, Chennai 600036, [email protected], Tel: (044) 445 8386, Fax: (044) 235 2120 Abstract This paper discusses the enhancements in the receiver design of TDMA Point to Multi-Point (PMP) system developed jointly by Centre for Development of Telematics (C-DOT) and Indian Institute of Technology, Madras. Novel techni...

In this paper some methods of using turbo coding in conjunction with π/4 shifted Differential Quadrature Phase Shift Keying (π/4 shifted DQPSK) modulation are proposed. The models used in the simulation of the running turbo coded system and their BER performances are presented for each case. The turbo coding rate was R=1/3 and R=1/2. The MAP algorithm, 12 iterations were used. A Log Likelihood ...