Curtis A. Siller

A broadband multiple access protocol for STM, ATM, and variable length data services on hybrid fiber-coax networks

This paper presents a broadband multiple access protocol for bidirectional hybrid fiber-coax (HFC) networks. The Adaptive Digital Access Protocol (ADAPt+) supports a full range of subscriber services via HFC networks with tree and branch topologies. The protocol efficiently accommodates different circuit- and packet-based access modes, such as synchronous transfer mode (STM), asynchronous transfer mode (ATM), and inherently variable length (VL) native data (for example, the Internet protocol [IP]). ADAPt+ allocates the available bandwidth efficiently and adapts to the changing traffic mix. In addition, the paper describes the medium access control (MAC) protocol for upstream and multiplexing/demultiplexing for downstream communication, its applicability to STM, ATM, and other native data applications, and its performance with respect to throughput, latency, and bandwidth efficiency. While discussed in the context of an HFC network, many aspects of ADAPt+ have relevance to wireless, fiber to the curb (FTTC), and fiber to the home (FTTH).

Adaptive MAC-layer protocol for multiservice digital access via tree and branch communication networks

Described here is an adaptive MAC-layer protocol that supports multiservice (STM and ATM) applications in the context of subscriber access to tree and branch (e.g., fiber-coaxial cable) networks. The protocol adapts to changing demands for a mix of circuit and cell mode applications, and efficiently allocates upstream and downstream bandwidth to a variety of bursty and isochronous traffic sources. In the case of a hybrid fiber-coaxial (HFC) network the protocol resides in customer premises equipment and a common head-end controller. A medium-access control (MAC) processor provides for dividing the time domain for a given digital bitstream into successive frames, each with multiple STM and ATM time slots. Within the STM region of a frame, variable length time slots are allocated to calls (e.g., telephony, video telephony) requiring different amounts of bandwidth. A contention access signaling channel is also provided in this region for call control and set-up requests. Within the ATM region fixed-length time slots accommodate one individual ATM cell. These ATM time slots may be reserved for a user for the duration of a call or burst of successive ATM cells, or shared via a contention process. At least one contention time slot is available for signaling messages related to ATM call control and set-up requests. Further, the fixed-length ATM time slots may be reserved by a user for the duration of a call, or shared through a contention process. This paper describes the MAC-layer protocol, its relation to circuit- and ATM- amenable applications, and its performance with respect to signaling throughput and latency, and bandwidth efficiency for several service scenarios.

Preliminary testing of teflon as a hydrophobic coating for microwave radomes

Transmission loss measurements under conditions of simulated rainfall and observed weatherability suggest that Teflon may be a suitable hydrophobic coating for microwave radomes. Teflon performance is compared with fumed silicone dioxide (FSD) and HMOD4, coatings which have been the subject of an earlier detailed study.

Evaluation of the radiation integral in terms of end-point contributions

Evaluation of the Kirchhoff integral which arises in the far-field computation of radiation from large aperture antennas frequently causes computational difficulty. This communication illustrates the utility of evaluating the integral in terms of end-point contributions. The special case of a pyramidal horn-reflector antenna is considered.

The influence of aperture shape on the radiation patterns of horn-reflector antennas

The role of aperture shape in influencing the far-zone radiation pattern in the vicinity of the main beam of horn-reflector antennas is examined. The three major types of horn-reflector antennas are considered-pyramidal, diagonal, and conical-and the influence of their aperture shape on the spatial character of antenna radiation is assessed.

Digital cross-connect systems: network-based vehicles for private T1 resource management

Operating companies are gradually considering network-based equipment as bases for T1 resource management. This emerging role for digital cross-connect systems (DCSs), wherein the operating company uses that equipment as vehicles for the operation, administration, and maintenance (OA&M) of private T1 networks, is described. It is noted that DCSs have only recently found acceptance as LEC (local exchange carrier) vehicles for intraLATA T1 resource management of private networks. These cross-connects are today deployed as small, dedicated units serving a single network, as partitioned fabrics providing a virtual service to several private networks, or as functional units within T1 multiplexers situated in central offices. The latter application can ultimately bring end users high functionality at reduced cost, while also providing direct gateways into public network services. This multiplexer approach points the way for an evolving seamless premises-to-network service, one in which a single protocol would interface a network management platform that directs OA&M functions to element managers that then interoperate with disparate communication equipment.<<ETX>>

A Nyquist-rate adaptation algorithm for fractionally spaced equalizers

Describes a time-domain Nyquist-rate algorithm that broadens the utility of fractional equalizers by permitting least-mean-square or true zero-forcing adaptation, more rapid convergence relative to synchronous coefficient updating, user specification of the end-to-end Nyquist channel, and elimination of the coefficient drift phenomenon. The investigation includes an analytical description of the algorithm, a functional circuit architecture, and reference to a computer simulation illustrating stable equalizer operation in the presence of dispersion on a digital subscriber loop.<<ETX>>

Design of multiple edge blinders for pyramidal horn reflector antennas

The design of multiple edge blinders for pyramidal horn reflector antennas is discussed. The blinders eliminate high sidelobes in the azimuthal plane near 90\deg for horizontal polarization at 4, 6, and 11 GHz. The successful design of multiple edge blinders for simultaneous operation in each of the three common carrier bands depends upon the suppression of an off-axis major lobe at 4 GHz and grating lobes which typically appear at 6 and 11 GHz. Using the blinder array factor and element pattern, it is shown that these lobes can be suppressed by properly choosing the blinder tilt angle \beta_{c} , the inclination of an individual blinder edge \delta , and an adequate number of edges N .

A radio relay antenna for application at 18 GHz

An antenna, designed for mast or roof-top mounting and incorporating esthetic considerations, has been tested for use in the 17.7-to 19.7-GHz frequency range. A gain efficiency of 60% and highly directive symmetrical radiation patterns have been obtained. Elevation beam aiming of plus or minus 4 degrees from horizontal is achieved by tilting an internal plane reflector. The antenna canister is also designed to provide space for electronic modules.