Charles R. Ratliff

Bio: Charles R. Ratliff is an academic researcher. The author has contributed to research in topics: Microcell & Multiplexing. The author has an hindex of 3, co-authored 3 publications receiving 613 citations.

Cellular communications system with centralized base stations and distributed antenna units

Abstract: A microcellular communications network includes a plurality of base station units and corresponding antenna units. The base station units are housed in a common location. Each includes either conventional transmitters and receivers or all digital transmitter and receiver equipment, and interface circuitry to a mobile telecommunications switching office. The microcell traffic output is applied to a frame generator/multiplexer. The output of the frame generator/multiplexer is applied to a digitally modulated laser. The laser output is conveyed by fiber to a remote antenna unit, which demultiplexes the microcell traffic signal and applies it to a digital-to-analog converter. The output of the digital-to-analog converter is applied to a power amplifier, which in turn is connected to a main antenna. RF signals from the mobile units are received at both a main and a diversity antenna. The received signals are filtered, digitized, multiplexed together and transmitted over the optical fiber back to the base station. The strongest signal is selected for use.

Cellular communications system with sectorization

Abstract: A method and apparatus for sectorizing coverage of a cellular communications area includes providing a remote unit having microcell antenna units. Each microcell antenna unit is configured to cover a particular sector. The remote unit is connected to a sectorized base station unit which is connected to a mobile telecommunications switching office. Separate digitized streams representative of telephone signals received from the mobile telecommunications switching office are generated corresponding to the microcell antenna units and the separate digitized streams are multiplexed and transmitted to the remote unit. The remote unit demultiplexes the multiplexed digitized streams into the separate digitized streams corresponding to the microcell antenna units and the separate digitized streams are converted to RF signals for coverage of a particular sector by the corresponding microcell antenna unit. Separate digitized streams are separately generated for each microcell antenna unit representative of RF signals received at the microcell antenna unit for a particular sector. The separately generated digitized streams are multiplexed at the remote unit and transmitted to the sectorized base station unit. At the sectorized base station unit, the multiplexed digitized streams are demultiplexed into the separate digitized streams corresponding to microcell antenna units and the separate digitized streams are converted to RF signals for provision to the mobile telecommunications switching office. Diversity at the remote units is also provided.

Cellular radio system with centralized located base stations and distributed antenna units

Abstract: A microcellular communications network includes a plurality of base station units (106) and corresponding antenna units (102). The base station units are housed in a common location (114). Each includes either conventional transmitters and receivers or all digital transmitter and receiver equipment, and interface circuitry (112) to a mobile telecommunications switching office (110). The microcell traffic output is applied to a frame generator/multiplexer. The output of the frame generator/multiplexer is applied to a digitally modulated laser. The laser output is conveyed by fiber to a remote antenna unit, which demultiplexes the microcell traffic signal and applies it to a digital-to-analog converter. The output of the digital-to-analog converter is applied to a power amplifier, which in turn is connected to a main antenna. RF signals from the mobile units are received at both a main and a diversity antenna. The received signals are filtered, digitized, multiplexed together and transmitted over the optical fiber back to the base station. The strongest signal is selected for use. Deployment of an all digital microcellular communications system occurs in two stages. The method thus allows for the benefit of a digital system to be accomplished in the early stages of the upgrade while without the expense of modifying the digital microcell antenna units in the second stage of the upgrade. Digital filtering of the digitized RF signal is also provided, so that only those channels associated with a cell are extracted for transmission to and from the antenna unit, and a digital passive handoff system provides for an FFT analysis of all traffic in the cell and passive switching in response thereto.

Repeaters for wireless communication systems

Abstract: A repeater and associated method of use includes at least one antenna element for communicating in one direction and at least one antenna element for communicating in another direction. A radio frequency uplink path and a radio frequency downlink path are coupled between the antennas. At least one of the radio frequency uplink path or the radio frequency downlink path includes an adaptive cancellation circuit. The adaptive cancellation circuit is configured to generate a cancellation signal without requiring an injected signal. The cancellation signal, when added to a radio frequency signal in the respective uplink and downlink paths, substantially reduces feedback signals present in the radio frequency signal.

System and method for design, tracking, measurement, prediction and optimization of data communication networks

Abstract: A system and method for design, tracking, measurement, prediction and optimization of data communications networks includes a site specific model of the physical environment, and performs a wide variety of different calculations for predicting network performance using a combination of prediction modes and measurement data based on the components used in the communications networks, the physical environment, and radio propagation characteristics.

System and method for remote programming of an implantable medical device

Abstract: A method and corresponding system for updating or installing new software loaded into the memory of an implantable medical device(IMD) implanted within a body of a patient is described. The updated or new software may be installed in the memory of the IMD without the patient having to travel to a clinic or hospital, and may be effected by employing modem telecommunication and Internet techniques in conjunction with a remote computer system.

Method and apparatus for integration of a wireless communication system with a cable t.v. system

Abstract: The present invention is a method and apparatus for integrating a personal communication system with a cable television plant. A set of radio antenna devices (RAD) (50A-50I) are connected to the cable plant (4). The RADs (50A-50I) provide frequency conversion and power control of signal received from the cable plant for wireless transmission to the remote units (24A-24C). The RADs (50A-50I) also provide power control and frequency conversion of wireless signals received from the remote units for transmission by the RADs (50A-50I) onto the cable plant (4). In addition to the functions of standard base stations and centralized controller, the CATV base station must also compensate for gain variations in the cable plant (4). The downstream power control is regulated by a RAD (50A-50I) reference signal which can be hidden within the CDMA signal for maximum efficiency.

Method and apparatus for coupling an antenna to a device

Abstract: Aspects of the subject disclosure may include, for example, receiving, by a feed point of a dielectric antenna, electromagnetic waves from a dielectric core coupled to the feed point without an electrical return path, where at least a portion of the dielectric antenna comprises a conductive surface, directing, by the feed point, the electromagnetic waves to a proximal portion of the dielectric antenna, and radiating, via an aperture of the dielectric antenna, a wireless signal responsive to the electromagnetic waves being received at the aperture. Other embodiments are disclosed.