Patent•
Method and apparatus for controlling transmission power in a CDMA cellular mobile telephone system
17 May 1992-
TL;DR: A power control system for a cellular mobile telephone system in which system users communicate information signals between one another via at least one cell-site using code division multiple access spread spectrum communication signals is described in this paper.
Abstract: A power control system for a cellular mobile telephone system in which system users communicate information signals between one another via at least one cell-site using code division multiple access spread spectrum communication signals. The power control system controls transmission signal power for each cellular mobile telephone in the cellular mobile telephone system wherein each cellular mobile telephone has an antenna (70), a transmitter (84), and a receiver (72, 74) and each cell-site also has an antenna (52), a transmitter (62), and a receiver (54, 56). Cell-site transmitted signal power is measured as received at the mobile unit. Transmitted power at the mobile unit is adjusted by transmit power control units (76, 80) in an opposite manner with respect to increases and decreases in received signal power. A power control feedback scheme may also be utilized. At the cell-site communicating with the mobile unit, the mobile unit transmitted power is measured by the received power measurement unit (60) at the cell-site. A command signal is generated at the cell-site and transmitted to the mobile unit for further adjusting mobile unit transmitter power corresponding to deviations in the cell-site received signal power. The feedback scheme is used to further adjust the mobile unit transmitter power so that mobile unit transmitted signals arrive at the cell-site at a desired power level.
Citations
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21 Jun 1991TL;DR: In this paper, a system and method for communicating information signals using spread spectrum communication techniques is presented, where PN sequences are constructed that provide orthogonality between the users so that mutual interference will be reduced, allowing higher capacity and better link performance.
Abstract: A system and method for communicating information signals using spread spectrum communication techniques. PN sequences are constructed that provide orthogonality between the users so that mutual interference will be reduced, allowing higher capacity and better link performance. With orthogonal PN codes, the cross-correlation is zero over a predetermined time interval, resulting in no interference between the orthogonal codes, provided only that the code time frames are time aligned with each other. In an exemplary embodiment, signals are communicated between a cell-site and mobile units using direct sequence spread spectrum communication signals. In the cell-to-mobile link, pilot, sync, paging and voice channels are defined. Information communicated on the cell-to-mobile link channels are, in general, encoded, interleaved, bi-phase shift key (BPSK) modulated with orthogonal covering of each BPSK symbol along with quadrature phase shift key (QPSK) spreading of the covered symbols. In the mobile-to-cell link, access and voice channels are defined. Information communicated on the mobile-to-cell link channels are, in general, encoded, interleaved, orthogonal signaling along with QPSK spreading.
1,891Â citations
Patent•
01 Aug 2008
TL;DR: In this article, the oxide semiconductor film has at least a crystallized region in a channel region, which is defined as a region of interest (ROI) for a semiconductor device.
Abstract: An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.
1,501Â citations
Patent•
16 Sep 1998
TL;DR: A location reporting paging communication system comprising space satellites, ground stations and a remote receiving unit adapted to resolve a global position from signals transmitted from a communication transmitter is described in this paper.
Abstract: A location reporting paging communication system comprising space satellites, ground stations and a remote receiving unit adapted to resolve a global position from signals transmitted from a communication transmitter. The subscriber in possession of the remote receiving unit updates the paging network with global positioning information. A caller paging a subscriber in possession of the remote receiving unit may request the global location of the remote receiving unit. The paging network could divulge or block such information from a caller depending on the requirements of the subscriber.
1,162Â citations
Patent•
11 Apr 1994TL;DR: In this article, a mobile station monitors the signal strength of pilots and reports the measured signal strength to a system controller via the base station through which it is communicating and terminates communication through the corresponding base station while communications through the other base station or base stations continue.
Abstract: In a code division multiple access (CDMA) spread spectrum cellular communication system in which a mobile station user communicates with another system user via at least one base station, wherein each base station transmits a common pilot signal of a different code phase with respect to other base stations in said system, a method for directing communications between said mobile station user and said base stations. The mobile station monitors the signal strength of pilots and reports the measured signal strength to a system controller via the base station through which it is communicating. Command messages from the system controller to a new base station and the mobiles station establishes communication through the new base station in addition to the communication through the current base station. When the mobile station detects the falling below a predetermined level of the signal strength of a pilot corresponding to at least one of the base stations through which the mobile station is communicating, the mobile station reports the measured signal strength indicative of the corresponding base station to the system controller via the base stations through which it is communicating. Command messages from the system controller to the identified base station and the mobiles station terminates communication through the corresponding base station while communications through the other base station or base stations continue.
865Â citations
Patent•
23 Oct 1995
TL;DR: In this article, a cellular telephone system includes a plurality of cell sites and a mobile telephone switching office, and call management, including selection of a cell site most appropriate for a call associated with a mobile unit, are made based on the geographic location of the mobile unit as opposed to the strength of signal associated with the call.
Abstract: A cellular telephone system includes a plurality of cell sites and a mobile telephone switching office. Call management, including selection of a cell site most appropriate for a call associated with a mobile unit, are made based on the geographic location of the mobile unit as opposed to the strength of the signal associated with the call. The geographic location of the mobile unit is precisely determined using a NAVSTAR global positioning system, or its equivalent. Each mobile unit includes a GPS receiver that receives information from a geostationary satellite to determine the precise location of the mobile unit. This position information is relayed to the cell site initially managing the mobile unit, and the mobile unit is handed off to a cell site that is most appropriate for the call. Initial selection of an entrance cell site is made based on signal strength, but further call management decisions are made based on location of the mobile unit.
826Â citations
References
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Patent•
15 Oct 1987TL;DR: In this article, a multiple access, spread spectrum communication system and method for providing high capacity communications to, from, or between a plurality of system users, using code-division-spread-spectrum communication signals is presented.
Abstract: A multiple access, spread spectrum communication system and method for providing high capacity communications to, from, or between a plurality of system users, using code-division-spread-spectrum communication signals. The communication system uses means for providing marginal isolation between user communication signals. The marginal isolation is provided by generating simultaneous multiple steerable beams; using an omni-directional antenna with polarization enhancement; using power control devices to adjust the output power for user generated communication signals either in response to their input activity level, or in accordance with a minimum allowable power for maintaining a communication link. The communication system can also employ a means for transmitting a predetermined pilot chip sequence contiguous with the code-division-spread-spectrum communication signals. In further embodiments the communication system employs a plurality of user terminals linked to each other or to other services through one or more terrestrial or satellite repeaters. Multiple satellite repeaters are operable in a new communication mode to obtain further gains in signal isolation.
1,218Â citations
Patent•
07 Nov 1989
TL;DR: In this article, the authors propose a system for directing communications between a mobile user and cell-sites as the mobile user changes cell-site service areas, which includes circuitry responsive to the indication for coupling communications between the mobile users and the other system users via the new cell site while the user remains in communication with the first cell site.
Abstract: In a cellular telephone system a system for directing communications between a mobile user and cell-sites as a mobile user changes cell-site service areas. The mobile user includes an apparatus for, while in communication with another system user via one cell-site, determining a transition of the mobile user from the cell-site service area to the service area of another cell-site. The system includes circuitry responsive to the indication for coupling communications between the mobile user and the other system user via the new cell-site while the mobile user also remains in communication with the system user via the first cell-site. The system further includes apparatus responsive to the coupling of the communications between the mobile user and the other system user via the new cell-site for terminating the communications between the mobile user and another system user via cell-site with communications continuing between the mobile user and the system user via the new cell-site.
683Â citations
Patent•
05 Nov 1990TL;DR: In this paper, a spread spectrum receiver subsystem for utilization in a CDMA cellular telephone having a searcher receiver (44) for scanning the time domain so as to use the PN processing gain and time discrimination properties of spread spectrum coding to determine the location and received signal strength of multiple receptions of a pilot signal traveling upon one or more physical propagation paths to reception.
Abstract: A spread spectrum receiver subsystem for utilization in a CDMA cellular telephone having a searcher receiver (44) for scanning the time domain so as to use the PN processing gain and time discrimination properties of spread spectrum coding to determine the location in the time domain and the received signal strength of multiple receptions of a pilot signal traveling upon one or more physical propagation paths to reception The searcher receiver (44) provides a control signal indicative of the received pilot signals of greatest strength and corresponding time relationship A data receiver (40, 42) receives spread spectrum communication signals accompanying each received pilot signal and is responsive to the searcher control signal for acquiring and demodulating a spread spectrum communication signal, concomitant with the pilot signal of greatest signal strength, and thus providing a corresponding encoded output signal bearing information
667Â citations
Patent•
03 May 1985TL;DR: In this paper, the power levels of first and second stations in a cellular radiotelephone system are dynamically adjusted from only one (10) of them, where the second station receives signals from the first and, on the basis of the level of those signals, first adjusts its own transmitter power level to be within a predetermined range.
Abstract: Power levels of first and second stations (10, 11) in a cellular radiotelephone system are dynamically adjusted from only one (10) of them. The second station receives signals from the first and, on the basis of the level of those signals, first adjusts its own transmitter power level to be within a predetermined range and then directs the adjustment of the power level of the first station to be within a predetermined range. Parameters used in processing call handoffs are also adjusted to correspond to the power level adjustments to prevent false handoffs due to the power level changes.
276Â citations
Patent•
23 Oct 1986TL;DR: In this paper, the authors proposed a wireless PBX network where a plurality of local user transceivers using a first separate unique chip sequence pattern for information communication and a second common chip pattern for call-set up.
Abstract: The present invention relates to a wireless PBX network wherein direct sequence spread spectrum multiple access is used for voice and data communications to support a plurality of local-local and local-external calls. The present wireless PBX arrangement comprises a plurality of local user transceivers using a first separate unique chip sequence patterns for information communication and a second common chip sequence pattern for call-set up; and a central PBX comprising (a) a plurality of PBX transceivers, each of which uses a separate first chip sequence pattern which is matched to a corresponding local user transceiver; (b) a switching means for interconnecting local users to each other or to an external network via the associated PBX transceivers; and (c) a call set-up receiver responsive solely to initial call set-up information sent by any user using the second common chip sequence pattern. Optional selection diversity or equal gain combining diversity and/or error correction encoding may also be included in the transceivers.
246Â citations