Ashok J Mehta

US Patent:

52991989, Mar 29, 1994

Filed:

Dec 6, 1990

Appl. No.:

7/622232

Inventors:

Stanley E. Kay - Rockville MD
John E. Corrigan - Washington DC
Daniel Wendling - Darnstown MD
Ashok Mehta - Gaithersburg MD
Michael Parr - San Diego CA

Assignee:

Hughes Aircraft Company - Los Angeles CA

International Classification:

H04J 316

US Classification:

370 953

Abstract:

A mobile telephone system multiplexes plural voice traffic channels on a single carrier using a TDMA protocol. The capacity of the mobile telephone system is increased by assigning voice traffic capacity, not on a conversation basis, but on a speech spurt basis. In order to avoid compromising the voice transmission capacity, control signals (for the allocation and deallocation of both forward and reverse traffic channels) are sent using multiple diversity, i. e. both time and frequency. In addition, to increase the number of available control channels, a control channel comprises a sub-divided portion of an otherwise equivalent voice traffic slot. For reverse allocation requests, which are transmitted over a contention access channel, power diversity is used in addition to time and frequency diversity.

US Patent:

53435133, Aug 30, 1994

Filed:

Apr 20, 1992

Appl. No.:

7/870976

Inventors:

Stanley E. Kay - Rockville MD
George D. Farmer - Frederick MD
Hans Bhatia - Germantown MD
Ashok D. Mehta - North Potomac MD
Christopher J. Kain - Damascus MD
Nicholas P. Sampson - Clarksburg MD

Assignee:

Hughes Aircraft Company - Los Angeles CA

International Classification:

H04M 1100
H04Q 700
H04J 316

US Classification:

379 59

Abstract:

A cellular system uses dynamic repartitioning and channel packing to improve capacity without impacting quality. Dynamic repartitioning is employed to convert a carrier which operates, at one time, as an analog carrier to operate, at a later time, as a digital carrier in response to changes in offered traffic. Alternatively, a carrier which, at one time, operates as a digital carrier is converted to operate, at a later time, as an analog carrier in response to changes in offered traffic. Channel packing is used to allocate as many digital channels as possible to as few digital carriers as possible. In a preferred embodiment, both repartitioning and channel packing are implemented in response to call origination or call termination.

US Patent:

54756898, Dec 12, 1995

Filed:

Jul 14, 1994

Appl. No.:

8/275161

Inventors:

Stanley Kay - Rockville MD
Ashok D. Mehta - Gaithersburg MD

Assignee:

Hughes Aircraft Company - Los Angeles CA

International Classification:

H04J 316

US Classification:

370 953

Abstract:

A cellular system supports dispatch and datagram operations. The architecture of a conventional cellular system, such as the GSM system, is modified by adding a local area network (TIL) where nodes on the network include various base switching controllers (BSC). The BSC has a Switching Interface Module (SIM) which provides an interface to the TIL. The TIL may also include one or more gateways (40) to landline based networks. The datagram operation uses an appropriate gateway to complete a data path which includes an RF segment to or from the BSC. Dispatch operations provide for switching by the BSC so that switching is at a level below the Mobile Switching Center (MSC). For example, compressed voice traffic received by the BSC may be transmitted over the TIL to another BSC from where it is sent over an RF segment to a mobile receiver (MS).

US Patent:

53675592, Nov 22, 1994

Filed:

May 11, 1992

Appl. No.:

7/881271

Inventors:

Stanley Kay - Rockville MD
Youngky Kim - N. Potomac MD
Lou King - Mt. Airy MD
Ashok D. Mehta - Gaithersburg MD
Charles Barnett - Sterling VA

Assignee:

Hughes Aircraft Company - Los Angeles CA

International Classification:

H04M 1100

US Classification:

379 60

Abstract:

Cellular handoff is improved by tailing or adapting the measurement time based on the characteristics of the received signal intensity or power. More particularly, base stations typically measure mobile signal power in order to determine the necessity for handoff and the identity of a new cell. The measurement time must be of a duration which is sufficient to characterize the environment of the mobile. In accordance with the invention, the duration of the measurement time is determined from the received signal itself. Once the duration of the measurement time is determined, that data may be passed to a target cell along with other handoff data.

US Patent:

55131832, Apr 30, 1996

Filed:

Jul 27, 1994

Appl. No.:

8/281389

Inventors:

Stanley E. Kay - Rockville MD
John E. Corrigan III - Chevy Chase MD
Daniel R. Wendling - Darnestown MD
Ashok D. Mehta - North Potomac MD
Michael I. Parr - San Diego CA

Assignee:

Hughes Aircraft Company - Los Angeles CA

International Classification:

H04J 316

US Classification:

370 953

Abstract:

A mobile telephone system multiplexes plural voice traffic channels on a single carrier using a TDMA protocol. The capacity of the mobile telephone system is increased by assigning voice traffic capacity, not on a conversation basis, but on an information burst basis. In order to avoid compromising the voice transmission capacity, control signals (for the allocation and deallocation of both forward and reverse traffic channels) are sent using multiple diversity, i. e. both time and frequency. In addition, to increase the number of available control channels, a control channel comprises a sub-divided portion of an otherwise equivalent voice traffic slot. For reverse allocation requests, which are transmitted over a contention access channel, power diversity is used in addition to time and frequency diversity.

US Patent:

56781806, Oct 14, 1997

Filed:

Jun 7, 1995

Appl. No.:

8/480727

Inventors:

Ashok Mehta - Potomac MD
Jim Hobza - Carlsbad CA
Stanley Kay - Rockville MD

Assignee:

Hughes Electronics - Los Angeles CA

International Classification:

H04Q 700
H04Q 900

US Classification:

455 331

Abstract:

A dispatch system and a cellular interconnect system are combined to form a single system in which dispatch and interconnect communications are made with use of common system equipment. Different system configurations are employed according to the number of cells in the system to minimize loss of cellular interconnect capacity arising from dispatch communication operations.

US Patent:

57038813, Dec 30, 1997

Filed:

Mar 9, 1993

Appl. No.:

8/028502

Inventors:

Stanley E. Kay - Rockville MD
Pradeep Kaul - Darnestown MD
Michael I. Parr - San Diego CA
Graham Avis - San Diego CA
John E. Corrigan - Chevy Chase MD
Daniel Wendling - Darnestown MD
Ashok D. Mehta - North Potomac MD

Assignee:

Hughes Electronics - Los Angeles CA

International Classification:

H04J 317

US Classification:

370468

Abstract:

A multisubscriber unit is disclosed for use of in a digital cellular communication system to communicate with a base transceiver station and eventually to switched telephone network. The multisubscriber unit connects to a plurality of individual subscriber telephones. It includes a plurality of upconverters, modulators, downconverters, demodulators speech compressors, speech decompressors, and voice activity detectors that are assigned to a subscriber telephone upon detection of an off hook signal from the telephone. Preferably, upon the detection of data to be transmitted, to channel allocation is requested from a pool of time division multiple access channels in a digital speech interpolation pool.

US Patent:

47788437, Oct 18, 1988

Filed:

Dec 9, 1986

Appl. No.:

6/939685

Inventors:

Murray C. Cooperman - Woodbridge NJ
Ashok K. Mehta - Piscataway NJ

Assignee:

NL Chemicals, Inc. - Hightstown NJ

International Classification:

C08G 6934

US Classification:

524606

Abstract:

A polyamide rheological additive especially for organic solvent-based compositions which comprises the reaction product of a defined polycarboxylic acid, active hydrogen compound and capping agent. The additive exhibits excellent efficiency and dispersibility and is especially effective when first predispersed in an organic solvent. Organic solvent-based compositions which may be thickened using the rheological additive are aromatic, aliphatic and some moderately polar solvent-based compositions.