EP0619662A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Protocol for packet data communication system
Assignee: Symbol Technologies LLC
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Filing: 1994-03-30
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Granted: —
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Expires: 2014-03-30
Abstract
Abstract A packet data transmission system is used to link a number of remote hand-held data-gathering units such as bar code readers to a central computer. Data packets are sent from the remote units by a spread spectrum RF link to intermediate base stations, then sent by the base stations to the central computer by a serial link. The remote hand-held units initiate an RF exchange to and from the base stations, receiving only during a time window following a transmission from the remote unit. The base stations cannot initiate an exchange with the remote units, but instead send data to the remote units only as part of the exchange. To alert a remote unit when a message is waiting at a base station to be sent to a particular unit, some of the acknowledge (base-to-remote) packets sent by the base station may contain an identification such as a list of all remote units (identified by ID number) which have messages waiting. Alternatively, a bit map can be used to identify these remotes. These base-to-remote packets with the identification of remotes with messages waiting are called "announcements." Each remote unit (if not engaged in regular exchanges for a time interval) periodically listens (activates its receiver) to receive an announcement packet containing such a list or bit map and decodes this announcement to see if it has a message waiting. If so, this remote unit then sends a transmit packet so the base can send the waiting message in an acknowledge packet.
Inventors
- 👤 Laroy Tymes
- 👤 Gregory B. Ennis
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 23:07
CPC Classifications
G; G06; G06K; G06K17/00; G06K17/0022; G06K7/00; G06K7/0008; G06K7/10; G06K7/10009; G06K7/10316; G06K7/10356; H; H04; H04B; H04B1/00; H04B1/69; H04B1/713; H04B1/7156; H04L; H04L5/00; H04L5/14; H04L5/1469; H04L5/1484; H04B2001/71563; Y; Y02; Y02D; Y02D30/00; Y02D30/70
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
111 words
A method of operating a communications system which has a base station and a plurality of remote units, comprising the steps of: a) sending from said base station an announcement message having an identification of particular ones of said remote units which have data messages waiting at said base station for transmission to said particular ones: b) intermittently turning on a receiver at each one of said remote units to receive said announcement message; c) sending from each one of said particular ones to said base station an inquiry message; and d) sending a data message from said base station to each one of said particular ones of said remote units.
Claim 2
Independent Claim
111 words
A method of operating a communications system which has a base station and a plurality of remote units, comprising the steps of: a) sending from said base station an announcement message having an identification of particular ones of said remote units which have data messages waiting at said base station for transmission to said particular ones: b) intermittently turning on a receiver at each one of said remote units to receive said announcement message; c) sending from each one of said particular ones to said base station an inquiry message; and d) sending a data message from said base station to each one of said particular ones of said remote units.
Claim 3
Dependent Claim
45 words
A method according to claim 1 wherein said remote terminals send message packets to said base station at times of their own choosing, and said base station responds to a message packet from a remote unit within no more than a fixed interval of time.
Claim 4
Dependent Claim
34 words
A method according to claim 1 wherein said step of intermittently turning on a receiver of said remote unit is at a selected time interval, and said time interval is changed according to conditions.
Claim 5
Dependent Claim
111 words
A communications system having a base station and a plurality of remote units, comprising: a) means for sending from said base station an announcement message having an identification of particular ones of said remote units which have data messages waiting at said base station for transmission to said particular ones; b) means for intermittently turning on a receiver at each one of said remote units to receive said announcement message: c) means for sending from each one of said particular ones to said base station an inquiry message; and d) means for sending a data message from said base station to each one of said particular ones of said remote units.
Claim 6
Dependent Claim
111 words
A communications system having a base station and a plurality of remote units, comprising: a) means for sending from said base station an announcement message having an identification of particular ones of said remote units which have data messages waiting at said base station for transmission to said particular ones; b) means for intermittently turning on a receiver at each one of said remote units to receive said announcement message: c) means for sending from each one of said particular ones to said base station an inquiry message; and d) means for sending a data message from said base station to each one of said particular ones of said remote units.
Claim 7
Dependent Claim
29 words
Apparatus according to claim 1 - 3 or 4 wherein said base station and said remote units send and receive said messages by spread spectrum RF transmission and reception.
Claim 8
Dependent Claim
31 words
Apparatus according to claim 1 - 3 or 4 or 5 wherein said identification of particular ones is by a bit-map specifying remote units by assigned bits in a bit field.
Claim 9
Dependent Claim
41 words
Apparatus according to claim 1 - 3 or one of 4 - 6 wherein said means for intermittently turning on a receiver of said remote unit operates at a selected time interval, and said time interval is changed according to conditions.
Claim 10
Independent Claim
92 words
A method of transmitting and receiving data packets at a communications unit, where said unit is one of a plurality of like units, comprising the steps of: a) transmitting a first data packet from said unit beginning at a first time selected by the unit; b) activating a receiver to receive at said unit a second packet during a second time period occurring only during a time interval after said first time, the second packet including an identification of particular ones of said like units that messages are waiting to be sent.
Claim 11
Independent Claim
92 words
A method of transmitting and receiving data packets at a communications unit, where said unit is one of a plurality of like units, comprising the steps of: a) transmitting a first data packet from said unit beginning at a first time selected by the unit; b) activating a receiver to receive at said unit a second packet during a second time period occurring only during a time interval after said first time, the second packet including an identification of particular ones of said like units that messages are waiting to be sent.
Claim 12
Dependent Claim
73 words
A method according to claim 8 wherein said unit and said other like units are of a plurality of remote stations associated with a base station, said base station transmitting said second packet, wherein preferably said identification is a bit-map of bits assigned to each of said remote stations, and wherein preferably said second packet is sent by said base station only in response to a data packet sent by said remote units.
Claim 13
Dependent Claim
57 words
A method according to claim 8 or 9 wherein a third packet is sent by said base station after a fixed period during which there have been no data packets transmitted from any of said remote units, said third packet including an identification of particular ones of said remote units that messages are waiting to be sent.
Claim 14
Independent Claim
112 words
A method of transmitting and receiving data packets in a network having a plurality of like remote units and a base station, comprising the steps of: a) transmitting first data packets from one of said remote units beginning at first times selected by said one remote unit; b) receiving at said one remote unit second packets from said base station, said second packets being received during a second time period occurring only in a selected time window after one of said first times, at least some of the second packets including an identification of selected ones of said remote units for which messages are waiting to be sent by said base station.
Claim 15
Independent Claim
112 words
A method of transmitting and receiving data packets in a network having a plurality of like remote units and a base station, comprising the steps of: a) transmitting first data packets from one of said remote units beginning at first times selected by said one remote unit; b) receiving at said one remote unit second packets from said base station, said second packets being received during a second time period occurring only in a selected time window after one of said first times, at least some of the second packets including an identification of selected ones of said remote units for which messages are waiting to be sent by said base station.
Claim 16
Dependent Claim
43 words
A method according to claim 11 including the step of periodically transmitting by said base station one of said second packets containing said identification and not in response to a first packet, if no first packets are received during a selected time period.
Claim 17
Independent Claim
55 words
A method of operating a communications system which has a base station and a plurality of remote units, comprising the steps of: a) sending an announcement message having an identification; b) turning on a receiver to receive said announcement message; c) sending to said base station an inquiry message; and d) sending a data message.
Claim 18
Independent Claim
55 words
A method of operating a communications system which has a base station and a plurality of remote units, comprising the steps of: a) sending an announcement message having an identification; b) turning on a receiver to receive said announcement message; c) sending to said base station an inquiry message; and d) sending a data message.
Claim 19
Independent Claim
42 words
A method of transmitting and receiving data packets in a network having a plurality of remote units and base station, comprising the steps of: a) transmitting first data packets from one of said remote units; b) receiving at remote unit second packets.
Claim 20
Independent Claim
42 words
A method of transmitting and receiving data packets in a network having a plurality of remote units and base station, comprising the steps of: a) transmitting first data packets from one of said remote units; b) receiving at remote unit second packets.
References Cited (Backward Citations)
No citation records indexed.
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