Manchester Code Research Articles

Simulation and Comparison of Advanced Modulation Formats for Wavelength Reuse in High-SpeedWDM-PON System

In recent years, the innovation in devices and schemes of physical layer plays an important role in promoting the development of WDM-PON (Wavelength Division MultiplexingPassive Optical Network).Among the key technologies adopted in the WDM-PON system, advanced modulation formats at downstream and remodulations at upstream attract the most attention. DPSK (Differential Phase Shift Keying Modulation), FSK(Frequency-Shift Keying), IRZ(Inverted Return-to-Zero) and Manchester are four of the most common formats and each of them was studied before, but, however, nobody compared and analyzed them together.So, we will do the job by numeralsimulation in this paper. During our simulation, the 40-Gbit/s FSK is generated through the demodulation of two DPSK signals and 40-Gbit/s Manchester signal bases of employing a delay interferometer (DI) and an optical delay line as format conversion device to convert RZ-DPSK(Return to Zero-Differential Phase Shift Keying Modulation) coding to Manchester coding, both of the two format generation schemes are novel.Meanwhile,this paper emphasizes the input optical power and dispersion tolerance, which both related to the sensitivity of the system. Analyze the sensitivity with DPSK, FSK, IRZ and Manchester, and then compare the four advanced modulation formats.

IRZ–Manchester coding for downstream signal modulation in an ONU-source-free WDM-PON

Inverted return-to-zero (IRZ)–Manchester coding is proposed for optical downstream signal using amplitude shift keying (ASK) modulation in an optical network unit (ONU)-source-free wavelength-division-multiplexing passive optical network (WDM-PON), and ASK modulation is used for the optical upstream signal generation using remodulation over the optical downstream signal. With IRZ–Manchester coding, differential phase shift keying (DPSK) modulation can be overlaid on the downstream optical ASK signal for broadcasting services. Our experimental results show that the IRZ–Manchester coded optical ASK downstream signal has no modulation extinction ratio restrictions from the overlaid DPSK modulation, and that the remodulated optical upstream signal has very limited signal crosstalk from the downstream signals. In comparison with the conventional schemes using only Manchester coding or IRZ modulation, the proposed IRZ–Manchester coded modulation scheme shows better performance under different PON upstream and downstream traffic bit rate ratios.

Study of FSK/IM orthogonal modulation system with optical Manchester-coded payload

We study the performance of an orthogonal modulation system with frequency-shift keying (FSK) label and optical Manchester-coded (MC) payload. Simulation result shows that by introducing an optical MC payload, the available extinction ratio (ER) value of a FSK and intensity modulation (IM) orthogonal modulation system can be improved from 5 to 9 dB for system optimization, exhibiting great advantages over the traditional non-return-to-zero (NRZ) payload. Besides, the bit error rate (BER) characteristics of both label and payload show a more remarkable advantage than that of NRZ coding, verifying itself as a perfect candidate for the payload coding method in orthogonal modulation systems.

Performance Enhancement by Threshold Level Control of a Receiver in WDM-PON System with Manchester Coded Downstream and NRZ Upstream Re-Modulation

We propose and demonstrate a scheme enhancing the performance of optical access networks with Manchester coded downstream and re-modulated NRZ coded upstream. It is achieved by threshold level control of a limiting amplifier at a receiver, and the minimum sensitivity of upstream is significantly improved for the re-modulation scheme with 5Gb/s Manchester coded downstream and 2.488Gb/s NRZ upstream data rates.

Link Reliability Improvement for Optical Wireless Communication Systems With Temporal-Domain Diversity Reception

We experimentally demonstrate a simple temporal- domain diversity reception (TD-DR) scheme to enhance the reliability of optical wireless transmission links corrupted by atmospheric turbulence (AT) effects. Both nonreturn-to-zero and Manchester encoded on-off-keying modulation schemes are studied in laboratory environments at a 1.25-Gb/s data rate. AT effects are emulated as a slowly varying log-normal intensity variation for the received signal. System bit-error ratio is tracked for the performance evaluation, and results show that the outage probability due to the AT-induced intensity fluctuation for a 1.25-Gb/s link using Manchester coding is reduced from 3.2%plusmn0.1% to <0.1%, when the TD-DR is employed.

Effects of Upstream Bit Rate on a Wavelength-Remodulated WDM-PON Based on Manchester or Inverse-Return-to-Zero Coding

We compare the performance of a wavelength remodulated wavelength-division-multiplexed passive optical network implemented using Manchester-coded or inverse-return-to-zero (IRZ)-coded signal downstream and non-return-to-zero remodulated signal upstream. We investigate the effects of varying differences between downstream and upstream bit rates on the two coding schemes. When the bit rate ratio of upstream to downstream is less than or equal to 50%, the performance of Manchester coding is better than that of IRZ coding. However, when the bit rate ratio of upstream to downstream is higher than 50%, Manchester code requires appropriate time delay between upstream and downstream signals, whereas IRZ code needs reduced extinction ratio in the downstream signal.

Enhancing Chaotic Communication Performances by Manchester Coding

A numerical analysis of an optical chaotic transmission system, based on the synchronization of two chaotic lasers, in a master-slave closed loop configuration is presented. At the transmitter, the master chaotic wave is superposed on the information message; at the receiver, the message is recovered by subtracting the synchronized slave chaotic wave from the received signal. The performances are analyzed in terms of the Q-factor, considering two different message modulation formats: the nonreturn-to-zero and the Manchester coding. The Manchester coding shows enhanced performances due to the shift of the signal spectrum to higher frequencies.

Enhanced performance of RSOA-based WDM PON by using Manchester coding

Feature Issue on Passive Optical Network Architectures and TechnologiesWe propose and demonstrate that the power budget and scalability of the wavelength-division-multiplexed passive optical network (WDM PON) implemented by using reflective semiconductor optical amplifiers (RSOAs) can be significantly improved by modulating the downstream signals in Manchester format instead of the conventional non-return-to-zero format. As an example, we experimentally show that the maximum transmission distance of the RSOA-based WDM PON can be increased by a factor of 2 by using the Manchester-encoded downstream signals.

Improving dispersion tolerance of manchester coding by incorporating duobinary coding

A Manchester-duobinary coding scheme is proposed to compact the optical spectrum compared with that using pure Manchester coding and thus demonstrate much larger tolerance against fiber dispersion. With this modulation format, the dispersion tolerance can be extended to nearly three times of that using pure Manchester coding. Dispersion tolerance of Manchester-duobinary is from -800 to +920 ps/nm at 2-dB power penalty

Noncoherent pulse compression

Pulse compression can be performed in noncoherent radars by using coded on-off keying (OOK). We show how any bipolar pulse-compression code (e.g., Barker) can be modified into unipolar OOK through Manchester coding. The resulted transmitted signal is a burst of dense subpulses, with pulse position modulation. In the receiver, the envelope-detected signal is aperiodically cross-correlated with a mismatched bipolar reference signal, yielding noncoherent integration with a low-sidelobe response. The concept can be used in simple radars where Doppler information is not required, in direct-detection laser radars and in ultrawideband (UWB) radars. Examples are given with bursts of 13 and 70 subpulses. Detection probabilities dependence on SNR is studied and compared with coherent processing.

DESIGN OF A MULTICODE BI-PHASE ENCODER FOR DATA TRANSMISSION

In this paper, we present a versatile Multicode Bi-Phase Encoder (MBPE) circuit capable of encoding five different Bi-Phase line codes, namely: Bi-Phase-Level (Bi-Φ-L), Bi-Phase-Mark (Bi-Φ-M), Bi-Phase-Space (Bi-Φ-S), Differential Manchester (DM) and Inverse Differential Manchester (IDM) codes. The design methodology is based on a new definition of these codes in terms of encoding rules and state diagrams, instead of the traditional way of representing them in terms of their bit transition. The operation mode of the MBPE is set by three selection lines, which can be either hardware or software controlled. This will facilitate the process of altering the data transmission protocol without the need of changing the encoder hardware. The functionality and design of the MBPE is outlined. VHDL has been used to describe the behavior of the MBPE whose operation was verified using the ModelSim XE II Simulation tools. Implementation and testing of the MBPE on XILINX Spartan-II FPGA showed that the MBPE circuit is capable of encoding NRZ data into any of the five codes.

Optical access network scheme with downstream Manchester coding and upstream NRZ remodulation

A novel optical access network with Manchester coded downstream and remodulated NRZ coded upstream is proposed and experimentally implemented in a 20 km standard singlemode fibre network. When the downstream light source is reused for the upstream signal, acceptably small penalty was observed compared to the unmodulated light source case.

Generation of all-fiber optical Manchester code using nonlinear polarization rotation

We experimentally demonstrate all-fiber optical Manchester code generation at 10 Gbit/s using nonlinear polarization rotation in a single 1- km highly-nonlinear fiber with the nonlinearity of 20.4 W-1km-1. 33-dB extinction ratio is achieved in a -4-dBm CW dummy channel by coinjecting orthogonally aligned two 8-dBm pumps into the Kerr medium. Our encoder functions with 10 Gbit/s NRZ data stream and 10 GHz optical clock as the pumps. We present the resultant waveform as well as the optical spectrum of the Manchester-coded output.

On subsurface wireless data acquisition system

Measurement, evaluation, and monitoring of subsurface objects often require wireless data transmission between an embedded sensor and an exterior host system. Such technologies find applications in many areas-medical imaging, space exploration, earth formation evaluation in oilfield industries, for example. This paper describes a complete wireless data acquisition system that includes design of a transceiver unit, as well as communication protocols for data encoding and decoding. Although the application considered in this paper pertains to the oilfield industry, the method is applicable to other areas as well. The transceiver design is highly constrained due to requirements on physical size, mechanical stability, and low-power consumption. The host antenna generally consists of ferrite-backed coils wound on a metallic cylinder. A critical requirement in the design of these coils is to produce a desired spatial variation of the magnetic field in a specified region. A genetic algorithm is used to optimize the location and excitation of each coil. A combination of finite-element method and superposition principle is used to speed up the solution of forward problem. The data measured by an embedded sensor are encoded with seven-bit cyclic redundancy code concatenated with Manchester code for error detection/correction and bit synchronization. Coded data are finally transmitted by binary frequency-shift keying modulation scheme. Numerical and experimental results for magnetic field, signal-to-noise ratio, and data demodulation are presented.

An Encoder for Differential Manchester and Inverse Differential Manchester Line Codes

A synchronous digital circuit for encoding differential Manchester and inverse differential Manchester codes is presented. The design is based on a new representation of these codes as Moore state machines, which is extracted from a new code definition through encoding equations. The encoder utilizes two flip-flops, one OR gate and one X-OR gate, which can be easily implemented in hardware using standard ICs or part of an LSI / VLSI circuit.

CMOS 공정을 이용한 무선인식 송수신 집적회로의 설계 및 제작

This paper describes the design and implementation of a passive transponder chip for RFID applications. Passive transponders do not have their own power supply, and therefore all power required for the operation of a passive transponder must be drawn from the field of the reader. The designed transponder consists of a full wave rectifier to generate a dc supply voltage, a 128-bit mask ROM to store the information, and Manchester coding and load modulation circuits to be used for transmitting the information from the transponder to the reader. The transponder with a size 410 x 900 <TEX>${\mu}$</TEX>m<TEX>$^2$</TEX> has been fabricated using 0.65 <TEX>${\mu}$</TEX>m 2-poly, 2-metal CMOS process. The measurement results show the data transmission rate of 3.9 kbps at RF frequency 125 kHz.

10 Gbit/s Manchester-encoded FSK-labelled optical signal transmission link

An optical signal consisting of a 10 Gbit/s Manchester-encoded intensity-modulated (IM) payload and a 156 Mbit/s frequency-shift-keying (FSK) label was generated, and its performance was evaluated in an 80 km standard singlemode-fibre link. It is shown that the FSK/IM labelling performance is greatly improved through high-speed Manchester coding.

Performance of Manchester-coded payload in an optical FSK labeling scheme

The modulation crosstalk between combined frequency-shift keying (FSK) and intensity modulation (IM) in an optical label-switching network is analyzed both theoretically and experimentally. A comparison between the performance of nonreturn-to-zero (NRZ) and Manchester-coded payload is made. It is shown that Manchester coding of the payload helps to suppress the crosstalk introduced into the optical FSK label, thus achieving better network performance than NRZ coding.

Encoder circuit for inverse differential Manchester code operating at any frequency

The inverse differential Manchester is a new code that has the same spectral efficiency as the differential Manchester code. Here, a modified encoder circuit that operates at any frequency is presented. It utilises few digital components, thus lending it for fabrication as a single medium-scale integration or part of a large-scale integration (LSI)/very LSI chip.

Estimation and cancellation of multi-user interference in synchronous fiber-optic PPM-CDMA system using Manchester coding

A multi-user interference estimation and cancellation technique is proposed for direct-detection fiber-optic code division multiple-access communication systems employing pulse-position modulation. In addition, Manchester codes are used in signaling the transmitted data to further improve the bit-error rate (BER). The multi-user interference of any user is estimated with the help of properties of modified prime code sequences. The estimated interference is canceled out from the received signal after the photo-detection process. We have used PIN photo-detector in our proposed system. An upper bound on the BER for the proposed system is derived and compared with a lower bound on the BER for the system without cancellation. In the presence of multiple users interference (MUI) and the Poisson shot noise model, our results clearly indicate that the performance, in terms of the BER, of the proposed system is significantly improved compared with that of the system without cancellation. The effect of thermal, dark current and surface leakage noise is insignificant compared to MUI and thus will not be considered in our calculation of BER.