Telecommunications – Interference signal transmission
Reexamination Certificate
1999-07-02
2001-02-20
Urban, Edward F. (Department: 2746)
Telecommunications
Interference signal transmission
C348S014160, C455S088000, C455S507000
Reexamination Certificate
active
06192216
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to wireless telephones and more particularly to apparatus for centrally controlling the operation and settings of gain control circuitry in remote transceivers that carry telephony signals between wireless telephones and a broadband distribution network that carries telephony signals to a telephone network.
BACKGROUND OF THE INVENTION
The prior art teaches the use of existing cable television network cables to carry telephony signals between a telephone network and remote transceiver sites in defined cells or sectors. The transceivers are used to establish wireless telephony communication links with wireless telephones that are operating within an area covered by each remote transceiver. To increase the number of wireless telephone subscribers that can use the wireless telephone system it has been suggested to decrease the size and operational range of each cell or sector, and to increase the number of cells or sectors required to provide wireless telephone service to a given area. Having cells or sectors of decreased size permits greater reuse of the limited number of frequency channels allocated for wireless telephone service because other cells or sectors located at a closer range can reuse the same frequency channels for additional calls without signal interference. The advantages of reducing cell or sector size to increase the call carrying capacity of the wireless telephone network is offset by the requirement for additional remote transceivers for the additional cells. This offset is minimized by utilizing an existing broadband distribution network to provide the communications path between remote transceivers in each of the cells or sectors and a central transceiver. The base transceiver station acts as the interface between the telephone network and the wireless telephone system, and the central transceiver acts as the wireless telephone system interface with the broadband distribution network.
To carry wireless telephony signals over a broadband distribution network, as described above, a predetermined bandwidth on the network is typically allocated for this purpose. However, as required, more bandwidth may be allocated to carry wireless telephony signals. To most efficiently use a given bandwidth to carry wireless telephony signals between wireless telephones and the telephone network, a combination of frequency and time division multiplexing is utilized. This requires base transceiver station equipment that acts as the interface with the telephone network and the wireless telephone system. With the base transceiver station equipment is a central transceiver (RASP), also called a Headend Interface Converter (HIC), that interfaces with the broadband distribution network, and it must function with telephony signals in the wide frequency spectrum of radio frequency signals on the telephone network, and up to 1000 Mhz over the broadband distribution network. This system also requires a plurality of remote transceivers, also called cable microcell integrators (CMIs) or Remote Antenna Drivers (RADs), in each of the cells or sectors that can carry many channels of telephony signals between the wireless telephones and the central transceiver via the broadband distribution network, without creating signal interference with the telephony signals in adjacent cells or sectors. In addition, the remote transceivers (RADs) must function with and translate telephony signals in the wide frequency spectrums of up to 1000 Mhz on the broadband distribution network and between 1850-1990 MHz for the radio link between remote transceivers and wireless telephones.
In addition, the remotely located transceivers and the broadband distribution network are exposed to numerous adverse conditions, such as temperature extremes, which adversely affect the power levels output from the transceivers, and affect losses and gains along the broadband distribution network. The power levels output from the remote transceivers must be constantly monitored and adjusted to compensate for these adverse conditions. In addition, such remote transceivers need to compensate not only for network variations between each remote transceiver and the central transceiver, but also for the temporal variations in the various network links between the remote and central transceivers.
SUMMARY OF THE INVENTION
Thus, there is a need in the art for transceivers or RADs for use in such a wireless telephony system to carry telephony signals between a telephone network and wireless telephones via a broadband distribution network along which are remotely distributed a plurality of the transceivers. The gain of these remote transceivers will be adjusted by the central transceiver which is monitoring the power level of signals received from each remote transceiver so that signals received from the wireless telephones are at a consistent level, that is within a relatively narrow acceptability range, when input to the central transceiver.
The above described need in the wireless telephone system prior art is satisfied by the present invention. A small transceiver is provided which is used in a wireless telephone system of the type briefly described above. These remotely located transceivers are used to carry telephony signals between wireless telephones and central transceivers via a broadband distribution network, such as HFC, fiber optic cable, or coaxial cable, on which the remote transceivers are hung and to which they are connected. Thus, these remote transceivers are remotely located and eliminate the need for prior art antenna towers to carry telephony signals between wireless telephones and central transceivers. Each remote transceiver has gain control circuitry by which the gain of the remote transceivers can be adjusted by the central transceiver which is monitoring the power level of a gain tone signal received from each remote transceiver. This is done so that the signal level of telephony signals from the wireless telephones and appearing at the input of the central transceiver are at a consistent level that is within a relatively narrow range acceptable to the central transceiver.
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Beasley, “The Advantages of Using Cable TV Distribution Plant for Linking PCS-Microcells”, IEEE International Conference on Selected Topics in Wireless Communications, pp. 292-295, 1992.
Donaldson et al., “Wireless Personal Communications Using CATV Distribution Networks”, Canadian Conference on Electrical and Computer Engineering, pp. 995-999, 1993.
Donaldson et al., “Wireless CATV Network Access for Personal Communications Using Simulcasting”. IEEE Transactions on Vehicular Technology vol. 43 issue 3, pp. 666-671, Aug. 1994.
Dawson Michael T.
Sabat, Jr. John
Hamilton Brook Smith & Reynolds P.C.
Perez-Gutierrez Rafael
Transcept, Inc.
Urban Edward F.
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