Patents by Inventor Mordechai Ritz
Mordechai Ritz has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 5838673Abstract: A system for minimizing co-channel interference between transmission sectors at their common periphery. The system exploits the geographic separation of potentially interfering mobile transmitters and utilizes transmission power control. The system employs sectored antennas in a combined frequency hopping, TDMA system wherein each subscriber in a particular sector is assigned a time slot in the system based upon that subscriber's geographic location within that sector. The transmission power in the sector is reduced during certain predetermined time slots and subscribers who are remote from the fringe of the sector are assigned to these power reduced time slots. During up-link the transmission power for subscribers located proximal to the fringe are reduced to cause less co-channel interference between their signals and the signals from other subscribers in different sectors having the same time slot.Type: GrantFiled: July 2, 1996Date of Patent: November 17, 1998Assignee: Geotek Industries, Inc.Inventors: Mordechai Ritz, Giora Silbershatz, Shmuel Miller
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Patent number: 5809401Abstract: A method and apparatus is provided for reducing interference in a radio communication link from a central site (230) to a mobile unit (228) in a cellular communication system. The central site (230) includes a first (202) and a second (216) antenna which serve the geographic region (214) in which the mobile unit (228) is located. The radio communication link may be provided by communicating a signal in a first radio communication channel between the first central site antenna (202) and the mobile unit (228). Similarly, the radio communication link may be provided by communicating a signal in a second radio communication channel between the second central site antenna (216) and the mobile unit (228). A measure of interference in the first radio communication channel providing the radio communication link is determined. The radio communication link is switched, in response to the measure of interference being above a predetermined threshold, from the first to the second radio communication channel.Type: GrantFiled: April 7, 1997Date of Patent: September 15, 1998Assignee: Motorola, Inc.Inventors: Reuven Meidan, Noam Livneh, Giora Silbershatz, Mordechai Ritz
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Patent number: 5737358Abstract: A multiple access communications system reuses a set of either N carrier frequencies or time slots in adjacent communications sites to provide more than N or T minimally cross-correlated frequency or time hopping communications channels respectively. A first set of communications channels is associated with a first of the communications sites. No two of the channels in the first set employ the same frequency or T time slots at the same time. A second set of communications channels is associated with a second of the adjacent communications sites. No two of the channels in the second set of channels employ the same one of the N carrier frequencies or T time slots at the same time. One or more sets of the minimally cross-correlated channels are further defined so that none of the channels in such sets employ the same frequency at the same time as more than a predetermined number of the channels in another of the sets of the minimally cross-correlated frequency-hopping communications channels.Type: GrantFiled: February 2, 1995Date of Patent: April 7, 1998Assignees: Geotek Communications, Inc., Rafael Armament Development AuthorityInventors: Mordechai Ritz, Giora Silbershatz, Noam Livneh, George Calhoun, Oliver Hilsenrath
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Patent number: 5678187Abstract: A method and apparatus is provided for reducing interference in a radio communication link from a central site (230) to a mobile unit (228) in a cellular communication system. The central site (230) includes a first (202) and a second (216) antenna which serve the geographic region (214) in which the mobile unit (228) is located. The radio communication link may be provided by communicating a signal in a first radio communication channel between the first central site antenna (202) and the mobile unit (228). Similarly, the radio communication link may be provided by communicating a signal in a second radio communication channel between the second central site antenna (216) and the mobile unit (228). A measure of interference in the first radio communication channel providing the radio communication link is determined. The radio communication link is switched, in response to the measure of interference being above a predetermined threshold, from the first to the second radio communication channel.Type: GrantFiled: June 16, 1995Date of Patent: October 14, 1997Assignee: Motorola, Inc.Inventors: Reuven Meidan, Noam Livneh, Giora Silbershatz, Mordechai Ritz
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Patent number: 5619493Abstract: A multiple access communications system reuses a set of N carrier frequencies in adjacent communications sites to provide more than N minimally cross-correlated frequency-hopping communications channels. A first set of communications channels is associated with a first of the communications sites. No two of the channels in the first set employ the same frequency at the same time. A second set of communications channels is associated with a second of the adjacent communications sites. No two of the channels in the second set of channels employ the same one of the N carrier frequencies at the same time. One or more sets of the minimally cross-correlated channels are further defined so that none of the channels in such sets employ the same frequency at the same time as more than a predetermined number of the channels in another of the sets of the minimally cross-correlated frequency-hopping communications channels.Type: GrantFiled: February 26, 1996Date of Patent: April 8, 1997Assignee: Rafael Armament Development AuthorityInventors: Mordechai Ritz, Noam Livneh, Giora Silbershatz
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Patent number: 5428818Abstract: A method and apparatus is provided for reducing interference in a radio communication link from a central site (230) to a mobile unit (228) in a cellular communication system. The central site (230) includes a first (202) and a second (216) antenna which serve the geographic region (214) in which the mobile unit (228) is located. The radio communication link may be provided by communicating a signal in a first radio communication channel between the first central site antenna (202) and the mobile unit (228). Similarly, the radio communication link may be provided by communicating a signal in a second radio communication channel between the second central site antenna (216) and the mobile unit (228). A measure of interference in the first radio communication channel providing the radio communication link is determined. The radio communication link is switched, in response to the measure of interference being above a predetermined threshold, from the first to the second radio communication channel.Type: GrantFiled: January 18, 1994Date of Patent: June 27, 1995Assignee: Motorola Inc.Inventors: Reuven Meidan, Noam Livneh, Giora Silbershatz, Mordechai Ritz
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Patent number: 5408496Abstract: A multiple access communications system reuses a set of N carrier frequencies in adjacent communications sites to provide more than N minimally cross-correlated frequency-hopping communications channels. A first set of communications channels is associated with a first of the communications sites. No two of the channels in the first set employ the same frequency at the same time. A second set of communications channels is associated with a second of the adjacent communications sites. No two of the channels in the second set of channels employ the same one of the N carrier frequencies at the same time. One or more sets of the minimally cross-correlated channels are further defined so that none of the channels in such sets employ the same frequency at the same time as more than a predetermined number of the channels in another of the sets of the minimally cross-correlated frequency-hopping communications channels.Type: GrantFiled: June 18, 1993Date of Patent: April 18, 1995Assignee: Rafael Armament Development AuthorityInventors: Mordechai Ritz, Noam Livneh, Giora Silbershatz
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Patent number: 5193102Abstract: A method and apparatus is provided for improving detection of data bits in data samples (120) of a hop of a slow frequency hopping spread spectrum signal (112). In the detecting process, the carrier to interference (C/l) power ratio of the hop is estimated (124) by using the data samples (120) of the hop. Subsequently, a data bit (130) is detected by using the estimated C/l power ratio (126). The detection process (128) may include utilizing maximum likelihood decoding techniques to derive a data bit (130) from decision metrics and the estimated C/l power ratio (126). The decision metrics correspond to a measurement of the distance of data samples (120) from constellation points within a constellation space representing data samples (120) previously used to generate decision metrics. The detection process (128) also may include utilizing the estimated C/l power ratio (126) in combining data samples (120) of the hop as received from two or more diversity receiver branches.Type: GrantFiled: November 18, 1991Date of Patent: March 9, 1993Assignee: Motorola, Inc.Inventors: Reuven Meidan, Noam Livneh, Giora Silbershatz, Mordechai Ritz