Helmut Strasser

Bio: Helmut Strasser is an academic researcher from Alcatel-Lucent. The author has contributed to research in topics: Terminal (electronics) & Transmission (telecommunications). The author has an hindex of 3, co-authored 5 publications receiving 53 citations.

Optical subscriber network

Abstract: A method is used for transmitting binary information in successive time slots of a time division multiplex frame format in an optical transmission network with a number of terminals and a central unit. At least one optical fiber is connected to the central unit and spreads to the terminals in a tree-like structure via one or more beam splitters and further optical fibers. An address is allocated to each terminal, and synchronization is performed for the transmitting operation of the terminal being phase-locked to the central unit in dependence of the signal delay time between the terminal and central unit. The transmitting level of the terminal is adjusted in dependence upon the line attenuation between terminal and central unit. The frame format has a number of time slots for line-switched information, as well as a number of bits for control and synchronization purposes.

Mobile telecommunication terminal

Abstract: A mobile telecommunication terminal, for example a hand-held mobile telephone which contains a hand-operated dynamo as power supply. This makes the device independent of batteries or, after failure of the battery, an emergency operation can be maintained. The hand-operated dynamo is preferably driven by means of a toothed rod which is moved via an operating lever protruding from the side wall of the device.

Device for the connection of subscriber terminals using optical transmission

Abstract: A device (3) for connecting subscriber terminals (2, 20) to an optical fibre transmission network. The plug-in socket (3) contains several plug-in socket locations (13) and a beam divider (4, 19) which divides the signal of the optical fibre network (1). If wavelength- selective beam dividers (19) are used, the plug-in socket locations are provided for different wavelength ranges.

Optical subscriber interconnect system

Abstract: To match the inherent needs of data traffic, office communications demand medium-speed connectionless packet transport in addition to circuit-switched voice and data transmission. Optical solutions to this requirement should be low in cost rather than extremely high in performance to be cost competitive with copper systems. A subscriber-premises system will be proposed which combines a digital private automatic branch exchange (PABX) with local area network (LAN) functionality. It is based on a double-star passive optical network, extending to optical wall outlets. The subsets with telephone functionality provide the opto/electrical conversion and give access to the packet channel via Terminal Adaptors (TA). Different types of customer LANs may coexist on the same network, since their data frames are embedded in an intermediate MAC-layer. The feasibility of transmission over multimode fibers at not aggregate bit rate of approx. 140 Mb/s at 1300 nm downstream and 780 nm upstream allowing the use of low-cost components (e.g. 780 nm compact-disc laser diodes) has been experimentally investigated. Calculations predict cost-of-ownership parity with conventional copper-based PABXs without LAN functionality and a cost-advantage over the usual separate LAN+PABX installations. The network topology, protocol and the implications of multimode transmission on the system will be discussed.

Optical communication system for bidirectional transmission between an exchange and a plurality of subscribers

Abstract: Optical communication system for bidirectional transmission of information signals between an exchange (1) and a plurality of subscriber devices (5), in which the exchange (1) is connected via one or two monomode optical waveguides (2) to an out-of-area device (3) which is common to a group of subscribers (5) and is located in their vicinity, and in which the subscriber devices (5) are connected via optical waveguides to the out-of-area device (3). The subscriber devices (5) have optical transmitters whose optical output signal is not adapted to the transmission characteristics of monomode optical waveguides, and the out-of-area device (3) contains a converter (10, 11) which converts the optical signals transmitted from the subscriber devices (5) to the out-of-area device (3) into optical signals which are suitable for further transmission via the monomode optical waveguide (2).

How modal noise in multimode fibers depends on source spectrum and fiber dispersion

Abstract: The speckle contrast for multimode fibers, and thus the modal noise, is essentially given by the impulse response of the fiber and the power spectrum of the source. Theoretical and experimental results show that laser sources with a large spectrum of narrow longitudinal modes may cause high speckle contrast and important modal noise over more than 1-km length in graded-index multimode fibers.

Fiber optic based subscriber terminal

Abstract: A subscriber terminal (22) within a business/residence (32) is in communications with a telecommunications network (12) through a fiber optic connection (33) to an optical network unit (20). Telephony signals are transmitted to and from the subscriber terminal to a user through a cordless telephone handset (26). During normal operation, the cordless telephone handset (26) operates in a cordless mode, passing telephony signals to a subscriber terminal telephone antenna (24) for transmission on the fiber optic connection (33). In the event of a power outage at the business/residence (32), the cordless telephone handset (26) switches to a wireless mode in order to continue to provide telephony communications. In the wireless mode, telephony communications are provided from the cordless telephone handset (26) to the telecommunications network (12) through a wireless telephone provider (14).

Optical communications systems for the subscriber area with optical amplifiers

Abstract: Optical communications system for the subscriber area with optical amplifiers. The system according to the in-vention is used to distribute information signals, particularly telephone signals, from a center to a large number of subscribers and to make possible a bidirectional transmission of telephone and data signals between the center and the subscribers. According to the invention, the network used for this purpose is a multistar fiber-optic network in which fiber-optic amplifiers (10, 11) are present between successive branch points. The information signals to be distributed are transmitted via the fiber-optic network with a first wavelength (.lambda.1) to the sub-scribers, and the subscriber-specific information signals to be transmitted from the center (1) to the subscribers (Ti) are converted by frequency modulation to a different frequency band (FB2) than the distribution signals (by frequency modulation) and transmitted to the subscribers at the same wavelengths as the distribution signals, and the subscriber-specific signals to be transmitted from the subscribers (Ti) to the center (1) are converted by frequency modulation to another frequency band (FB3) and are transmitted optically to the center with a second wavelength (.lambda.2). This optical signal is amplified at suitable points (A) and several alternative embodiments for this amplifi-cation are indicated.

Optical data communications network with a plurality of optical transmitters and a common optical receiver connected via a passive optical network

Abstract: An optical data communications network, for example a TPON (telecommunications over passive optical networks) network, has a common optical receiver and a plurality of optical transmitters connected to the common optical receiver by a passive optical network which consists of optical splitters/combiners linked by lengths of an optical fibre. The optical signals produced respectively by the different optical transmitters are interleaved together in a predetermined time-division multiple access format and are modulated using a return-to-zero modulation format. The common optical receiver can operate satisfactorily at desirably-high bit rates despite wide variations in the power levels of the optical signals reaching the receiver from the different transmitters, which variations arise due to the different attenuations experienced by those signals as they propagate along optical fibre paths of different lengths containing different numbers of splitters/combiners. As a result, power levelling of the transmitters is not required.

Duplication in decision trees

Abstract: A packet classification system, apparatus, and corresponding apparatus are provided for enabling packet classification. A processor of a security appliance coupled to a network uses a classifier table having a plurality of rules, the plurality of rules having at least one field, to build a decision tree structure for packet classification. Duplication in the decision tree may be identified, producing a wider, shallower decision tree that may result in shorter search times with reduced memory requirements for storing the decision tree. A number of operations needed to identify duplication in the decision tree may be reduced, thereby increasing speed and efficiency of a compiler building the decision tree.