Photonics for Solving Unbundling in Next-Generation WDM-PON

This paper describes development of a novel mid-infrared light emitting diode (LED) and photodiode (PD) light source/detector combination and use within a non-dispersive infrared (NDIR) carbon dioxide gas sensor. The LED/PD based NDIR sensor provides fast stabilisation time (time required to turn on the sensor from cold, warm up, take and report a measurement, and power down again ≈1 second), longevity (>15 years), low power consumption and low cost. Described performance is compatible with “fit and forget” wireless deployed sensors in applications such as indoor air quality monitoring/control & energy conservation in buildings, transport systems, horticultural greenhouses and portable deployment for safety, industrial and medical applications. Fast stabilisation time, low intrinsic power consumption and cycled operation offer typical energy consumption per measurement of mJ's, providing extended operation using battery and/or energy harvesting strategies (measurement interval of ≈ 2 minutes provides >10 years operation from one AA battery). Specific performance data is provided in relation to measurement accuracy and noise, temperature performance, cross sensitivity, measurement range (two pathlength variants are described covering ambient through to 100% gas concentration), comparison with NDIR utilizing thermal source/pyroelectric light source/detector combination and compatibility with energy harvesting. Semiconductor based LED/PD processing together with injection moulded reflective optics and simple assembly provide a route to low cost high volume manufacturing.

Joint port-cost and power-consumption savings in hybrid hierarchical optical networks

We demonstrate the 40-Gb/s upstream transmission in the 60-km reach wavelength-division-multiplexed passive optical network (WDM PON) implemented by using directly modulated reflective semiconductor optical amplifiers (RSOAs) and self-homodyne receivers. It is difficult to operate the RSOA at 40 Gb/s due to its limited modulation bandwidth. To overcome this problem and generate 40-Gb/s upstream signal, we utilize the quadrature phase-shift-keying (QPSK) format and the offset polarization-division-multiplexing (PDM) technique. For this purpose, we install two RSOAs at each ONU and provide the seed light for these RSOAs by polarization-multiplexing the outputs of two lasers with a small frequency offset (20 GHz). This frequency offset is used to separate the polarization-multiplexed seed light by using a simple delay-line interferometer (DLI), instead of the polarization-beam splitter and polarization controller, at the ONU. The separated seed light is modulated by each RSOA at 20 Gb/s in the QPSK format, and then combined again by the DLI before sent back to the central office (CO). The results show that this WDM PON can support the transmission of 40-Gb/s channels spaced at 50 GHz over 60 km without using any remote optical amplifiers.

We generate the phase-modulated signal by utilizing the chirp characteristics of the directly-modulated reflective semiconductor optical amplifier (RSOA) for the cost-effective realization of a long-reach wavelength-division-multiplexed passive optical network (WDM PON). We first investigate the relation between the amplitude and phase modulation indices in a directly-modulated RSOA and optimize these modulation indices to maximize the symbol distance on the constellation diagram. The results show that, by operating the RSOA under this optimum condition, we can achieve the excellent receiver sensitivity of -49.8 dBm at 1.25 Gb/s. We implement a long-reach WDM PON by using the phase-modulated RSOAs and self-homodyne receivers, and demonstrate the error-free transmission of 1.25-Gb/s signal over a 110-km long link without using any optical amplifiers.

We have proposed a memory based recursive FFT design which has much less gate counts, lower power consumption and higher speed. The proposed architecture has three main advantages (1) fewer butterfly iteration to reduce power consumption, (2) pipeline of radix-22 butterfly to speed up clock frequency, (3) even distribution of memory access to make utilization efficiency in SRAM ports. In summary, the speed performance of our design easily satisfies most application requirements of Fixed 802.16d and Mobile 802.16e WiMAX, which uses OFDMA modulated wireless communication system. Our design also occupies lesser area, hence lower cost and power consumption.

Most datacenter network designs overwhelmingly use expensive and power-consuming electronic switches or expensive active optical switches with long reconfiguration time. In this thesis, we explore architectural solutions to leverage the design elements of Passive Optical Cross-Connection Networks with Multiple Planes (POXN/MPs) and Passive Optical Cross-Connection Networks with Multiple Planes and Bundled Ports (POXN/MP-BPs), both of which consist primarily of passive optical fabrics and optical transceivers that replace groups of switches in either hierarchical or recursively defined networks. Through simple physical interconnections, our proposed architectures allow datacenters to incrementally scale up in network capacity and scale out in total number of racks with low cost and power consumption. To lower overhead and adapt to the types of real datacenter scenarios that are possible with POXN/MP-BPs, we propose the new Multiple Channels with Bundled Ports Distributed Access Protocol (MCBDAP), which benefits applications involving higher proportions of inter-rack traffic than intra-rack traffic.

The International Mobile Telecommunications-2020 (IMT-2020) specifies the data rates for enhanced mobile broadband (eMBB) is approximately 10 Gb/s. Millimetre-wave (mmWave) has a vast spectrum and can be used with only slight authorisation, making it an ideal solution for eMBB. This paper proposes optimal detectors with low cost, low power consumption, and low complexity for mmWave massive multi-user multiple-input multiple-output (MU-MIMO) communication. The mmWave broadband communication faces many challenges in system implementation. One of the challenges of mmWave broadband systems is using the analog-to-digital converter (ADC) in the receiver. The ADC power consumption will significantly increase with the frequency bandwidth. The ADC power consumption will also considerably increase with the bit number used in the conversion simultaneously. The mmWave broadband communication also challenges the cost of transmitters, especially wideband linear amplifiers are costly. Hence, it is necessary to transmit a signal with a low peak-to-average power ratio (PAPR) to relax the linearity of the power amplifier. The radio-frequency (RF) port connects to two high-precision ADCs in conventional MIMO systems. Scaling such architectures to massive multiple-input multiple-output (MIMO) with hundreds or thousands of active antenna elements would lead to excessive-high power consumption and hardware costs. Hence, this paper proposes optimal detections for massive multi-user (MU) MIMO-GFDM communications with coarse quantisation. It achieves substantial cost and power savings and provides a high system capacity. The optimal detections for coarse quantisation in large-scale MU-MIMO-GFDM systems have minimal capability loss compared with the ideal case. There is no additional base-band processing complexity. The simulation results show that the SNR gap between the second mismatched quantiser and the precise quantiser is small. When the ratio of receiving and transmitting antennas is the same, the larger the number of antennas, the smaller the SNR difference between the second mismatch quantiser and the precise quantiser.

The use of autonomous sensors for analyzing wide bands of radio frequency spectrum requires using the high-speed analog-to-digital converters (ADC). The operation of such devices with high bit resolution requires several watts of power. One-bit ADC will reduce power consumption and simplify the analog part of the receiver. The goal of the research is to determine the features and conditions under which it is advisable to analyze the radio frequency spectrum in a sophisticated radio electronic environment using a one-bit ADC. The problem of using such ADC is the deterioration of the signal-to-noise ratio (SNR) and the occurrence of spurious spectral components at its’ medium and high values. The task of spectrum sensing is complicated by the fact that a large number of signals with different values of bandwidth and SNR can be simultaneously present in the analyzed frequency band. After a one-bit ADC, the energy of the complex signal remains unchanged regardless of its shape. Therefore, at high SNR values, the signal energy flows into spurious spectral components. When the bandwidth of the signal increases to 30% of analyzed frequency range and higher, the spurious spectral components are transformed into a broadband pedestal. Analytical dependencies have been obtained that allow us to calculate the values of the SNR at which signals can be detected and spurious spectral components appear. These dependencies take into account the parameters of the Welch periodogram and the level of spectrum occupancy. The results of the analysis of real signals showed that the shape of the signal spectrum after one-bit ADC repeats the shape of the spectrum after an 8-bit ADC, except for the absence of some weak signals. The cost for simplified hardware implementation and lower power consumption when using one-bit ADC compared to ADC with higher resolution is a narrowing of the dynamic range of signals. The use of one-bit ADC for spectrum sensing will be justified only when there is information on the analyzed bandwidth occupancy and the SNR of the signals that can be observed.

In the article the possibility of using a smartphone with an integrated set of necessary technical means (several video cameras, accelerometers, gyroscope, magnetometer, GPS sensor, GSM and Wi-Fi wireless communication) for implementing the technology of video recording of vehicle speed is investigated and established. The main algorithmic and software components of a smartphone are proposed, which allow to identify and to accompany a vehicle, as well as to determine its speed. Installation and initial setup of the device is simple. It is only necessary to measure and enter in the device height of its arrangement. In the article the possibility of using a smartphone with an integrated set of necessary technical means for implementing the technology of video recording of vehicle speed is investigated and established. The smartphone has a low cost and power consumption, the ability to operate in the required temperature range, as well as a set of physically built-in necessary technical means: several video cameras, accelerometers, gyroscope, magnetometer, GPS sensor, GSM and Wi-Fi wireless communication. Due to its low power consumption, it can also run on solar panels during the day when no other power source is available. The cost of a smartphone with very good characteristics does not exceed 10,000 UAH. The paper proposes the main components of the algorithmic support of the device. The use of the Lucas-Kanade method for the implementation of tracking and the calculation in the interpixel space of the coordinates of the points of the vehicle's trajectory will improve the accuracy of measurements of the traveled distance and the vehicle's speed on short sections of the trajectory. The proposed algorithm for calculating the vehicle speed requires entering only one parameter - the height of the device. Therefore, installation and initial setup of the device is simple. It is enough to measure and enter this parameter into the device. Large-scale introduction of a device for measuring vehicle speed, built on the basis of a smartphone, is possible due to relatively small investments in the development of its mechanical part, algorithmic and software.

Circuit Emulation Services (CES) technology has emerged as an option to mitigate traditional TDM circuits supporting legacy applications across managed packet networks. Since Ethernet Passive Optical Network (EPON) is becoming a major technology for pervasive access. The primary benefits of CES over EPON (CESoEPON) are the low cost and simplicity of deployment to support all types of legacy TDM applications across EPONs. Thus, the QoS-guarantee for highly delay-sensitive services on EPONs could be enhanced. This paper investigates a preemptive priority transmission technique that works on MAC and PHY layer of EPONs. The proposed novel scheme effectively reduces the frame queuing delay as well as jitter, so as to enhance precise time synchronization in EPONs. Through simulation experiments, we show that the proposed method achieves superior and precise QoS control compared to existing non-preemptive methods. Finally, we present a general conclusion of the paper.

Recently, FTTH has finally emerged from the R&D stage and became a commercial reality. For example, in Japan, it has been reported that the total number of FTTH subscribers exceeded 1.5 million in 2004. In US, there have been numerous announcements of FTTH deployments by both operating companies and municipalities. It appears that this trend is rapidly spreading all over the world. At present, most of the FTTH deployments utilize TDM PON (such as GPON and EPON). However, WDM PON is beginning to attract significant attention, as Korea started a large-scale field traial this year. In fact, WDM PON has long been considered as an ultimate solution for the access networks due to its large capacity, easy management, network security, and upgradeability. In this paper, we review the current issues in WDM PON and report the relevant technical progresses achieved at KAIST. The subjects to be covered include low-cost WDM light sources (such as spectrum-sliced incoherent light sources and ASE-injected Fabry-Perot lasers), techniques for the delivery of broadcast services in WDM PON, wavelength-tracking technique for the wavelength-selective devices placed at the un-powered remote node, survivable WDM PON architectures, and fault monitoring and localization techniques.

Wavelength division multiplexing passive optical networks (WDM PONs) can dynamically offer each end user a unique optical wavelength for data transmission as well as the possibility of wavelength reuse and aggregation, thereby ensuring scalability in bandwidth assignment. In this paper, we propose a new byte size clock (BSC) reservation MAC scheme that not only arbitrates upstream transmission and prevents optical collisions, but also varies bandwidth according to demand and priority, reduces request delay using pre-allocation and delta compression, and handles the addition/reconfiguration of network nodes efficiently. The new access scheme exploits both WDM and TDM to cater for both light and heavy bandwidth requirements and supports both Ethernet and ATM packets without segmenting or aggregating them. Our proposed protocol is not only backward compatible with APON and EPON, but also provides a better utilization of the access link in terms of the throughput and delay. In addition, the amount of pre-allocated bandwidth can be minimized using delta compression, which in turns reduces the latency due to the request and grant mechanism. We analyzed, evaluated, and simulated the performance and practicality of the proposed scheme.

An Ethernet passive optical network (EPON) is an optical access network that allows a higher data rate with low power consumption. To improve energy savings for an EPON, the sleep and doze modes for the optical network units (ONUs) play a pivotal role. Many prediction schemes have been proposed to control these modes. To increase the prediction accuracy, this study proposes an energy-efficient approach that uses a support vector regression (SVR) model. A dynamic bandwidth allocation (DBA) scheme called SVR-DBA is designed to allocate bandwidth to ONUs more efficiently and fairly. To determine the effectiveness of the proposed scheme, simulations are performed. The simulation results show that the proposed scheme decreases energy consumption for ONUs by up to 47% and fulfills the quality-of-service (QoS) requirements in terms of delay, jitter, and packet loss.

DOI: 10.1049/ic:20070284 ISBN: 978-3-8007-3042-1 Location: Berlin, Germany Conference date: 16-20 Sept. 2007 Format: PDF We derive the performance and critical design issues of optical-coding based centralized live PON monitoring technique allowing more than 512 clients. We consider PON geographical distribution models in our performance evaluation. (2 pages) Inspec keywords: condition monitoring; encoding; optical fibre networks Subjects: Optical fibre networks; Codes

Emerging wireless technologies will play an important role in home network applications. Chaotic UWB technology has several inherent properties that are suited to home networks. In particular, applications have been focused such as low power consumption, low complexity, and low cost. In this paper, we describe the chaotic signal based UWB systems and the optimum sample number to minimize the bit error rate of the chaotic on-off keying. Moreover, we propose new scheme using the optical orthogonal code based chaotic on-off keying in an asynchronous channel for simultaneously operating piconets environment: all users are allowed to transmit their signal at any time, and moreover there is usually no network synchronization or coordinator among users.