Subscriber Unit Research Articles

Topology of optical networks FTTH (FIBER-TO-THE-HOME)

This article describes different architecture of access networks, access protocols; also, we analyzed the characteristics of optical networks FTTH (Fiber to the Home). The optical fiber with today is the main transport medium in the backbone and metro network. Using of fiber optic cable instead of copper cable has allowed to significantly increasing the quality of service. The greatest potential for broadband networks today have a fiber-optic technology under the general term FTTX (Fiber To The X - fiber to the X point), in which from the node connection to a specified location (point X) comes optics, and then to the subscriber - copper cable (and possible option, in which optics routed directly to a subscriber unit).Fiber optic access networks currently based on different architectures and technologies. Standards for these technologies and available of equipment make development of service-provider networks without risks. The success of their work stimulate to the dynamic development of the industry. Nowadays the PON architecture became very popular. The main factors of the most configurations of Ethernet FTTH it is the flexibility of the business model and the ability to support future services.

ЭЛЕКТРОННАЯ ИНФОРМАЦИЯ И ЕЕ НОСИТЕЛИ В УГОЛОВНО-ПРОЦЕССУАЛЬНОМ ДОКАЗЫВАНИИ: РАЗВИТИЕ ПРАВОВОГО РЕГУЛИРОВАНИЯ

The author considers the development of the Russian Criminal Procedure Institution of using digital information and its carriers in criminal case proving. It is stated that the institution dates back to 2010 since the adoption of the Federal Law № 143-FZ, which introduced Clause 186.1 “Obtaining information about connections between subscribers and (or) subscriber units” into the RF Criminal Procedure Code. Since then, the organization providing communication services have been providing submitting information in a variety of physical media. The author proves the prospects for the development of electronic information backup and many other issues of dealing with digital information and its carriers. Attention is drawn to the fact that criminal proceedings should be developed on account of the modern information and communication relations in society.

Field Measurement and Analysis of Long-Reach and High-Splitting-Ratio 10G-EPON With Optical Amplifier in Central Office

It is important to economize the infrastructure of the access network and enhance its profitability because it represents the greatest part of network infrastructure cost. As 10G-EPON can be cost-effectively shared among various access services, it is one of the strong candidates to reduce the infrastructure cost of the next-generation access network. To further enhance cost effectiveness, it is useful to improve the acceptable link budget of access systems by using optical amplifiers (OAs), which can increase the splitting ratios and extend the reachable distance of the system. In this paper, we demonstrate an $N$ :1 redundant 10G-EPON system with dual-rate central-office-set-type semiconductor optical amplifier (CO-SOA). Our 10G-EPON system reduces OPEX and CAPEX due to its extended reachable distance and elimination of intermediate offices while keeping its system reliability with the $N$ :1 protection system. Moreover, we also develop a method for estimating the total reachable distance of 10G-EPON systems with OAs in order to quantitatively evaluate the effect of extending reachable distance on various combinations of splitting ratio based on the results of actual demonstrations. Analyses of field measurement results clarify that the proposed system has sufficient design flexibility so as to satisfy the subscriber distribution requirements as regards the factors of splitting ratio and reachable distance. The results indicate that the $N$ :1 optical subscriber unit protection with CO-SOAs is a promising approach to practical 10G-EPON systems that are cost effective and reliable.

Delay fairness in reconfigurable and energy efficient TWDM PON

In Time and Wavelength Division Multiplexed (TWDM) Passive Optical Networks (PONs), dynamically (de)activating Optical Subscriber Units (OSUs) and assigning Optical Network Units (ONUs) to the active OSUs helps improving the OLT energy efficiency and balancing the network load.However, energy efficiency improvement is traded with a delay increase due to the finite ONU tuning speed and the potential increase of the normalized load with respect to the number of active OSUs. Moreover, even though load balance potentially assures delay balance, the scheduling and assignment of ONUs to OSUs might cause ONU delay unbalance (i.e., delay unfairness). Indeed, if an ONU is forced to tune at each reconfiguration it suffers a high delay penalty due to its limited tuning time.In this study, the impact of the ONU scheduling and assignment to OSUs upon network reconfiguration on the average frame delay unbalance is evaluated. Then, a method that balances the average frame delay by swapping the tuning ONU upon reconfiguration is proposed, for some critical scenarios. Simulation and experimental results show that the delay unbalance is large when the number of active ONUs is small (e.g., at network start up or when the majority of the ONUs is inactive/sleeping). In this case, the proposed method effectively balances the delay experienced by ONUs without impacting the OLT energy savings.

Field Trial of Long-Reach and High-Splitting λ-Tunable TWDM-PON

This paper presents the world's first field trial of a 40-km reach and over 512-split symmetric-rate 40-Gbit/s λ-tunable time and wavelength division multiplexing passive optical network (TWDM-PON) that utilizes our newly developed high-speed λ-tunable optical network unit transceivers and automatic gain controlled semiconductor optical amplifier-based PON extender for repeater and central office use. The upstream signals for C-band and downstream signals for L+-band in our developed λ-tunable TWDM-PON comply with the wavelength plan of ITU-T G.989 series. In a field trial, we successfully demonstrate error free λ-tunable transmission for the 40-km reach and 1024-split (maximum number) symmetric-rate 40-Gbit/s λ-tunable TWDM-PON over installed standard single-mode fiber links, and advanced network functions such as dynamic load balancing, incremental system upgrade, optical subscriber unit protection, and OLT equipment power saving are also confirmed.

512-ONU Real-Time Dynamic Load Balancing With Few Wavelength Reallocations in 40 Gbps λ-Tunable WDM/TDM-PON [Invited

The wavelength (λ)-tunable wavelength-division multiplexing/time-division multiplexing passive optical network (WDM/TDM-PON) can distribute traffic loads fairly by dynamically reallocating a certain number of optical network units (ONUs) from highly loaded optical subscriber units (OSUs) to lightly loaded OSUs. This reallocation can be executed by hitless λ-tuning. However, hitless λ-tuning causes delays or fluctuations in traffic. To reduce these penalties, the number of wavelength reallocations should be suppressed. Thus, we proposed a dynamic-load-balancing (DLB) algorithm that can distribute traffic loads among OSUs with few wavelength reallocations. However, no demonstration of the proposed DLB algorithm had been conducted up to now, and the impact of the reallocation frequency on the average latency remained unevaluated. In this paper, we demonstrate the DLB algorithm in a 40-Gbps λ-tunable WDM/TDM-PON. The demonstrations confirm that our DLB algorithm can distribute 512-ONU traffic loads fairly among 4 OSUs in real time with fewer reallocation frequencies compared to the conventional round-robin algorithm, and little impact on average latency, with various input traffic rates.

First experimental demonstration of dynamic bandwidth allocation for multiple 10 G‐EPON systems

Integrated dynamic bandwidth allocation with an overlap scheme that improves the bandwidth efficiency of aggregated access networks is implemented and demonstrated on the 10 G Ethernet passive optical network (EPON)-based prototype system for the first time. Experiments revealed that the prototype system can achieve more than 99% bandwidth efficiency with only 150 kB aggregation buffers in each optical subscriber unit.

Long-Reach and High-Splitting-Ratio 10G-EPON System With Semiconductor Optical Amplifier and N:1 OSU Protection

We successfully demonstrate a 41.3-km-reach and 128-split 10G-EPON system with dual-rate semiconductor optical amplifier on a commercial access network infrastructure. It uses N:1 optical subscriber unit (OSU) protection in order to improve system reliability cost-effectively. N:1 OSU protection also can switch from active system to redundant system without any frame loss. Moreover, the quality of bidirectional frame transmission is not degraded after switching, even with four-class priority control. Error free transmission over 130 hours is also confirmed. These results indicate that N:1 OSU protection with automatic level control semiconductor optical amplifiers is a promising approach to practical 10G-EPON systems that are cost-effective and reliable.

Theoretical aspects of designing a wireless communication network with broadband access to the main network infrastructure

The problem of designing wireless communication networks when the use of traditional cable technologies is inappropriate for data exchange between the computer networks is discussed. A link between network segments built with Wi-Fi on the basis of broadband-access WiMAX is proposed. Features of theoretical calculation of Wi-Fi networks with broadband access in relation to the main network infrastructure are considered. An expanded algorithm for designing Wi-Fi that increases the precision of computation of the coverage area of Wi-Fi access points and the geometry of wireless transport links on the basis of radio-signal propagation in planar and spatial projections (2D and 3D). An algorithm is given for determining the geometry of the base station and WiMAX subscriber units with the resulting Fresnel zones being identified. The proposed algorithm is tested by an example of designing a communication network for a group of interconnected Wi-Fi access points providing extended WLAN coverage for mobile devices in an enclosed indoor large and elevated area. The obtained results show that use of the algorithms that have been developed for designing wireless networks of the given class is effective.

Patient Dissatisfaction as a Determinant of Voluntary Disenrollment in a Managed Care Organization

An unsatisfactory patient experience during care may lead to a higher probability of disenrollment from a managed care organization (MCO). Compared with previous studies of general dissatisfaction, we examined the effects of specific outpatient visit dissatisfaction on subsequent voluntary disenrollment of 18 809 MCO subscriber units that had at least 1 completed postvisit satisfaction survey in 2000, 2001, or 2002. Subscriber units that reported dissatisfaction with care access, practitioner interaction, or overall visit experience had significantly increased likelihood of voluntary disenrollment from this MCO compared with subscriber units with a satisfactory visit experience.

Deliberately Designed Asynchronous Transmission Scheme for MIMO Systems

Oversampling at each receive antenna is equivalent to having multiple polyphase components with correlated channel gains and colored noise, provided that the signal bandwidth is higher than Nyquist bandwidth. To exploit the potential of these polyphase components in the MIMO systems, this letter advocates the approach of using deliberately designed asynchronous transmission instead of the synchronous transmission usually employed. Simulations show that the asynchronous transmission can easily outperform its synchronous counterparts. Moreover, it opens up the possibility of using fewer antennas at the receiver, particularly in a subscriber unit where there are severe constraints on size, weight, and power consumption.

The Effect of Antenna Physics on Fading Correlation and the Capacity of Multielement Antenna Systems

In this paper, we investigate the effects of antenna directivity and antenna orientation on fading correlation and, therefore, the channel capacity in multiple-input-multiple-output communication systems by means of a spherical simulation model. The correlation is caused by the mutual interaction of the scattering environment and antenna elements. To study the effect of antenna directivity and orientations on the correlation and channel capacity in a more realistic environment, we extend the ldquoone-ringrdquo model to a spherical scattering environment, which is appropriate for narrowband 3D Rayleigh fading. In our model, scatterers around a subscriber unit are distributed over a sphere centered on the antenna array in the subscriber unit. Antenna directivity is included in a precise way, and the antenna array can be placed in any orientation. Any type of antenna can be studied in the model. Through simulation, we find that directive antenna elements in linear broadside arrays make the channel capacity more strongly directive than when antenna elements are isotropic. Moreover, different antenna patterns and orientations have different outage capacities depending on the interaction of antenna directivities and the incident waves, which shows that the antenna pattern and orientation affect the channel capacity to some extent. In the uniformly scatter-rich environment, the microstrip antenna array can have 10% higher outage capacity than that of the dipole antenna array.

Reliability and performance of a true enhancement mode HIGFET for wireless applications

Freescale’s true enhancement mode (EMODE) HIGFET is a high performance single supply technology used for wireless power amplifiers. It is the first technology of its kind to be produced in a high volume manufacturing environment. The EMODE HIGFET intrinsic reliability was evaluated using a conventional three temperature DC accelerated stress test. The device used for these tests has a total gate width of 0.6 mm, a gate length of 0.8 μm, and a die thickness of 3 mils. The device has no through-wafer vias, is representative of the unit cell for larger devices, and was processed using a production mask set. For targeted applications with a system life of 5 years, the first expected failure at 150 °C for the 1 ppm level was determined to be 82 years at a 90% lower confidence level, which exceeds the reliability requirements for subscriber unit power amplifiers by a wide margin. This work demonstrates that EMODE HIGFET devices are high performance RF devices with intrinsic reliability well in excess of anticipated system requirements.

Impact of Antenna Coupling on 2 $\times$ 2 MIMO Communications

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The impact of mutual coupling induced by two closely spaced minimum scattering antennas at the subscriber unit on 2 <formula formulatype="inline"><tex>$\times$</tex></formula> 2 multiple-input multiple-output channels and communications is investigated. Both (de)correlation effects and variations of antenna gain resulting from coupling mechanisms are considered. Relationships between coupling and correlations/channel Frobenius norm are discussed, pointing out the role of the interelement spacing, the array orientation, and the richness of scattering. The analysis also yields useful insight into the influence of mutual coupling on capacity and system performance. </para>

Raman amplification-based WDM-PON architecture with centralized Raman pump-driven, spectrum-sliced erbium ASE and polarization-insensitive EAMs

We propose a novel wavelength division multiplexed (WDM) passive optical network (PON) architecture based on the distributed Raman amplification and pump recycling techniques, which features fully bidirectional transmission, relaxed signal power margin, and active light source-free, colorless subscriber units. The reuse of non-negligible residual Raman pump power as a pump for an erbium fiber-based upstream broadband ASE source allows for fully-centralized control of light sources at optical network units (ONUs), while distributed Raman amplification over a transmission link enables us to obtain lossless low power signal transmission. Furthermore, low-cost and colorless ONUs can be realized by use of the Raman pump-recycled erbium ASE and polarization-insensitive electroabsorption modulators. Error-free upstream transmission over a 50 km fiber link is successfully achieved at a data rate of 622 Mbit/s.

Method and apparatus for the provision of information signals based upon speech recognition

A wireless system comprises at least one subscriber unit in wireless communication with an infrastructure. Each subscriber unit implements a speech recognition client, and the infrastructure comprises a speech recognition server. A given subscriber unit takes as input an unencoded speech signal that is subsequently parameterized by the speech recognition client. The parameterized speech is then provided to the speech recognition server that, in turn, performs speech recognition analysis on the parameterized speech. Information signals, based in part upon any recognized utterances identified by the speech recognition analysis, are subsequently provided to the subscriber unit. The information signals may be used to control the subscriber unit itself; to control one or more devices coupled to the subscriber unit, or may be operated upon by the subscriber unit or devices coupled thereto.

Opposite-sector uplink interference in broadband FWA networks in high-rise cities

A deterministic propagation model is used to simulate broadband radio propagation at 3.5 GHz for a fixed wireless access (FWA) network in a high-rise city environment, with linear antenna polarisation. It is shown that some rooftop locations are unsuitable positions for subscriber units (SUs), due to the existence of single- or multiple-bounce reflected rays causing uplink interference. Furthermore, it is shown that it is usually possible to find an SU position just a few metres away on the same rooftop that gives much lower uplink interference.

A security method for passive double star optical access systems

AbstractIn a passive double star optical access system, an optical line terminal and multiple subscriber units are connected in a Point to Multi‐Point (P‐MP) configuration. In this case, the downstream signals from the optical line terminal are broadcast and delivered to all of the subscribers. Therefore, security is necessary for the communication of each subscriber to be protected from the other subscribers. In this paper, of the previously proposed encryption methods, we focus on stream ciphers that feature a compact cryptography circuit and are affected slightly by the bit errors generated in the transmission path, define the unique conditions of this system, and propose an encryption method for downstream signals that satisfies these system conditions. This new proposed encryption method features strengthening resistance to attack by using the upstream signal as the key and can be implemented in a small‐scale circuit. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(4): 42–49, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10068

Broadband wireless access solutions based on OFDM access in IEEE 802.16

Broadband wireless access is the most challenging segment of the wireless revolution since it has to demonstrate a viable alternative to the cable modem and DSL technologies that are strongly entrenched in the last mile access environment. The Analysis, Research, and Consultancy (ARC) Group forecasts that the fixed wireless deployments in both homes and businesses will reach almost 28 million by 2005, with North America and Western Europe accounting for 24 percent and 27 percent of these, respectively. Whether the promise of BWA will materialize depends on its appeal to telecom operators from the perspective of deployment economics, where the critical factor is the ease of installation of broadband wireless subscriber units. This ultimately leads to nonprofessional installation of integrated all-indoor BWSUs. Consequently the physical layer (PHY) has to mitigate the very tough impairments that characterize these non-line-of-sight environments. In this context we overview the work of the one of the IEEE 802.16 standard subcommittee projects that deals with a BWA solution based on OFDM access (OFDMA) aiming at the most challenging NLOS scenarios.

ＵＨＦ上り帯域利用双方向ＣＡＴＶシステムでのディジタル伝送における流合雑音の影響

In this paper, it is shown that upstream digital signals are affected by the ingress noise in the upstream band of a two-way CATV system. The carrier-to-noise ratio of the digital data signal may be reflected by the immunity characteristics of each subscriber's unit, which consists of a CATV protector connected to a coaxial cable. It was found by bit-error-rate measurement in the two-way CATV model system that the value of the relative operating level is smaller in the UHF upstream band than the value in the HF to VHF one.