Itt Corporation

International Telephone and Telegraph Corporation

U.S. Holding Co., Inc.

Stuart O Goldman

Matthew W Thomson

Erik A Lissakers

Leonard E Bogan

An improved cellular mobile radio telephone system is described wherein the switching matrices used to provide communication paths between subscribers is also used to provide paths for carrying control information between a network control and the various transceivers, receivers and transmitters at cell sites. Additionally, statistical multiplexers are provided at the cell sites for multiplexing control signals for many transceivers, receivers and transmitters onto the transmission facilities connecting the cell site with the network control system. At the network control system, apparatus is provided to reformat and packetize control signals from many statistical multiplexers and present the reformatted, packetized information to a network control processor.

Cellular mobile radio service telephone system

The locating function of a cellular mobile radio telephone system is implemented so that, when the locating radio detects a sustained change from a very low signal quality or amplitude (indicating background noise rather than an active call in an adjacent cell) to a higher quality or amplitude (indicating the start of a call in one of the adjacent cells), the radio will modify its filtering process so that previous sample values (which can be attributed, for example, to noise before the start of the call) will not be used in the averaging process. The result of this improvement is that values reported from the locating radio during the initial portion of the call (0 to 20 seconds) will not be reported artifically low. This allows the system to make decisions about handoff during this initial portion of the call. Additionally, rather than having the locating radio take equal samples from each of the possible voice channels, in accordance with the invention, there are two scanning tasks. The first task is to indeed look at all of the voice channels, and to establish a table of those channels with signal present. The second task is to look at only the channels in the table. The first scan task could be implemented either as a periodic scan occuring every n seconds or as a background task taking n seconds to complete. Since the second scan task has a vastly reduced number of channels to monitor, more samples can be taken in a unit time and thus the locating value reported to the system will be more accurate with less variation.

Cellular mobile radio subscriber location detection

In a cellular mobile radio-telephone system, a hand-off procedure is implemented by use of idle voice channel transceiver at relay stations of cells contiguous the site of a mobile station. The receiving portion of each transceiver is provided with tuning circuitry permitting a detuning from a preassigned idle channel frequency to the present broadcast frequency assignment of the mobile station. A set of measurements of broadcast signal is made at the detuned idle channels to determine the cell of best signal. The mobile station is then handed off to the cell of best signal.

Cellular mobile radio hand-off utilizing voice channel

In a telephone system, particularly a mobile radio-telephone system, incorporating statistical multiplexers and control concentrators for the arranging and formatting of digitized data, the data is formatted with operational codes designating specific meaning and any one of a plurality of levels of protection to be offered data transmitted via the telephone system. A back-up memory is connected to the statistical multiplexer to enable a retransmission of a batch of data in the event that the batch had been received with error. Full duplex communication is provided. A circular sequence number interleaved among batches of the data is utilized by an error detector at a receiving site to determine the presence of all portions of a batch of data. Transmission of specified operational codes and additional data as required in the reverse direction commands a retransmission and also provides for acknowledgement of receipt of a data batch with and without error.

Data control for telephone system

A cellular mobile radio-telephone system incorporates hand-off equipment for effecting a hand-off of communication links coupled to a mobile subscriber transceiver as the transceiver travels from one cell to an adjoining cell. The hand-off equipment includes a filter which smoothes voice channel signals received from the mobile transceivers so as to permit a more precise determination as to when a reduction in signal amplitude indicates the need for a hand-off. The operation of the filter includes long and short term averaging of a sequence of signal samples. Circuitry is also provided for predicting a time of signal fade-out based on differences in the amplitude of successive samples or groups of samples. Also disclosed is circuitry for commanding a change in transmitter gain in a transceiver as a function of signal fade-out.

Growing community of inventors

Columbus, OH, United States of America

Stuart O Goldman