EP0593289A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Frequency hopping spread spectrum data communications system
Assignee: LXE LLC
•
Filing: 1993-10-13
•
Granted: —
•
Expires: 2013-10-13
Abstract
Abstract A frequency hopping spread spectrum wireless data communications network is disclosed. Time mark frames are transmitted by each base station at a regular cadence and each time mark frame contains all information necessary to determine the hopping sequence of channels, a sub-set of possible channels in use, and the particular channel upon which the time mark was transmitted. Receipt of the time mark resynchronizes a slot clock that is used by the wireless terminals in implementing a media access protocol with defined synchronous time slots. The base station to roaming terminal radio link is half duplex. Each base station broadcasts an end-of-message frame during a hop period that indicates that it has no more data to send during that hop. If there are no outbound messages a roaming terminal needs to send, it puts its receiver in a low power mode until the next hop time approaches. Look ahead acquisition of the hopping sequence for a nearby base station when the received signal level for the current base station drops is also disclosed.
Inventors
- 👤 John W. Avery
- 👤 W. Burchall Cooper
- 👤 Kenneth P. Nelson
- 👤 Donald A. Jones
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 09:52
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/69; H04B1/713; H04B1/7143; H04B1/7156; H04B7/00; H04B7/24; H04B7/26; H04B7/2621; H04B2001/71563; H04W; H04W36/00; H04W36/08; H04W48/00; H04W48/08; H04W56/00; H04W74/00; Y; Y02; Y02D; Y02D30/00; Y02D30/70
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
246 words
In a radio frequency data communication system of the type comprising at least one base station and a plurality of terminals, said system employing a media access protocol of the type that defines a plurality of discrete time slots generated locally at each of said plurality of terminals and at said base station in response to a slot synchronizing signal broadcast from said base station, a frequency hopping spread spectrum transmitter at said base station for transmitting an information signal for a predetermined hop period on each of a predetermined plurality of carrier frequencies in a predetermined sequence, a time mark generator at said base station for generating a time mark frame that is provided as at least a part of said information signal for at least some of said plurality of carrier frequencies, said time mark frame including information for synchronizing a receiver at each of said plurality of terminals to receive said information signal on each of said predetermined plurality of carrier frequencies in said predetermined sequence; characterized by: a terminal slot synchronizer at each of said plurality of terminals for defining the start of a next one of said discrete time slots a predetermined period of time after receipt of each said time mark frame so that said time mark frame serves as said slot synchronizing signal and synchronizes both said discrete time slots and said predetermined sequence of said plurality of carrier frequencies between said base station and said plurality of terminals.
Claim 2
Dependent Claim
39 words
A radio frequency data communication system as in Claim 1 further characterized by: said time mark generator providing said time mark frame as at least a part of said information signal for each of said plurality of carrier frequencies.
Claim 3
Dependent Claim
117 words
A radio frequency data communication system as in claim 1 further characterized by: said predetermined sequence being a first predetermined sequence selected from a predetermined plurality of sets of predetermined sequences of said plurality of carrier frequencies; each said time mark frame includes a base address field that identifies said first predetermined sequence as the particular one of said predetermined plurality of sets of predetermined sequences of said plurality of carrier frequencies upon which said base station is transmitting; and each said receiver at each said terminal receiving said time mark frame receives said information signal on each of said predetermined plurality of carrier frequencies in said first predetermined sequence in response to said base address field.
Claim 4
Dependent Claim
85 words
A radio frequency data communication system as in Claim 1 further characterized by: a number of said discrete time slots that occur for each said predetermined hop period being selectively variable; each said time mark frame including a number of slots field that identifies said number of said discrete time slots; and each said terminal slot synchronizer at each of said plurality of terminals including a slot counter and timer for locally generating said discrete time slots in response to said number of slots field.
Claim 5
Dependent Claim
79 words
A radio frequency data communication system as in Claim 1 further characterized by: a duration of each of said discrete time slots being selectively variable; each said time mark frame including a slot duration field that identifies said duration of each of said discrete time slots; and each said terminal slot synchronizer at each of said plurality of terminals including a slot counter and timer for locally generating said discrete time slots in response to said slot duration field.
Claim 6
Dependent Claim
49 words
A radio frequency data communication system as in Claim A further characterized by: said time mark generator causing each said time mark frame to include a channel number field that identifies a particular one of said plurality of carrier frequencies upon which said time mark frame is being transmitted.
Claim 7
Dependent Claim
73 words
A radio frequency data communication system as in Claim 1 further characterized by: said predetermined sequence being a particular predetermined sequence selected from a set of predetermined sequences; and each of said predetermined plurality of carrier frequencies corresponds on a one-to-one basis with one of a predetermined plurality of channels, and each of said predetermined plurality of channels is associated on a one-to-one basis with one of a plurality of distinct channel numbers.
Claim 8
Dependent Claim
36 words
A radio frequency data communication system as in claim 7 further characterized by: each member of said set of predetermined sequences being substantially orthogonal to each of the remaining members of said set of predetermined sequences.
Claim 9
Dependent Claim
70 words
A radio frequency data communication system as in claim 8 further characterized by: each member of said set of predetermined sequences being a sequence, Z1 ,Z2 , Z₃ .....Z Y-1 , for which said channel number is defined by a multiplicative generator of the form Z i+1 = (XZ i ) MOD (Y) where Y is a positive prime integer and X is positive integer in the range [1, (Y-1)].
Claim 10
Dependent Claim
22 words
A radio frequency data communication system as in claim 9 further characterized by: X being chosen from the set consisting of [2,3,5,8,12,14,18,19,20,21,22,26].
Claim 11
Dependent Claim
46 words
A radio frequency data communication system as in claim 7 further characterized by: said time mark generator at each of said plurality of base stations providing said time mark frame as at least a part of said information signal for each of said plurality of channels.
Claim 12
Dependent Claim
59 words
A radio frequency data communication system as in claim 7 further characterized by: each said frequency hopping spread spectrum transmitter at each said base station transmits using a member of said set of predetermined sequences that is different than the member of said set of predetermined sequences used by a nearest other one of said plurality of base stations.
Claim 13
Dependent Claim
90 words
A radio frequency data communication system as in claim 7 further characterized by: at each of said plurality of base stations, each said time mark frame including a base address field that identifies a particular member of said set of predetermined sequences upon which said base station is transmitting; and each said receiver at each said terminal receiving said time mark frame receives said information signal on each channel in a sequence that is said particular member of said set of predetermined sequences in response to said base address field.
Claim 14
Dependent Claim
85 words
A radio frequency data communication system as in claim 7 further characterized by: a number of said discrete time slots that occur for each said predetermined hop period being selectively variable; each said time mark frame including a number of slots field that identifies said number of said discrete time slots; and each said terminal slot synchronizer at each of said plurality of terminals including a slot counter and timer for locally generating said discrete time slots in response to said number of slots field.
Claim 15
Dependent Claim
79 words
A radio frequency data communication system as in claim 7 further characterized by: a duration of each of said discrete time slots being selectively variable; each said time mark frame including a slot duration field that identifies said duration of each of said discrete time slots; and each said terminal slot synchronizer at each of said plurality of terminals including a slot counter and timer for locally generating said discrete time slots in response to said slot duration field.
Claim 16
Dependent Claim
46 words
A radio frequency data communication system as in claim 7 further characterized by: said time mark generator causing each said time mark frame to include a channel number field that identifies a particular one of said channels upon which said time mark frame is being transmitted.
Claim 17
Dependent Claim
203 words
A terminal for use in communicating with at least one base station in a wireless radio frequency data transmission network of the type including a radio receiver, a tuner connected to said radio receiver for selectively tuning its receive frequency in response to a frequency control signal to provide a received signal, a demodulator having a digital output, said demodulator being connected to said radio receiver and said tuner to provide a received digital signal on said digital output in response to variations in said received signal, a low power controller connected to said demodulator and to said radio receiver for timing a predetermined hop time interval commencing with its detection of said time mark signal; characterized by: said low power controller monitoring said received digital signal from said digital output for a time mark signal and providing said frequency control signal to said tuner in response to information in said time mark signal, monitoring said received digital signal from said digital output for an end of message signal, and powering down at least a portion of said radio receiver for at least a portion of the remainder of said hop time interval in response to receipt of said end of message signal.
Claim 18
Dependent Claim
153 words
A terminal for use in communicating with at least one base station in a wireless radio frequency data transmission network as in Claim 17 further characterized by: a level detector connected to said tuner for providing a level signal indicative of the power of said received signal; and said low power controller powering down at least said portion of said radio receiver for at least said portion of the remainder of said hop time interval in response to receipt of said end of message signal when said level signal is above a predetermined threshold value, and alternately changing said frequency control signal and monitoring said received digital signal on a different channel for an occurrence of said time mark signal for at least said portion of said remainder of said hop time interval in response to receipt of said end of message signal when said level signal is below said predetermined threshold value.
Claim 19
Dependent Claim
252 words
A terminal for use in communicating with at least one base station in a wireless radio frequency data transmission network as in Claim 17 wherein said terminal is of the type including a radio transmitter and said tuner is also connected to said radio transmitter for selectively changing its transmit frequency in response to said frequency control signal, a modulator having a digital input, said modulator being connected to said radio transmitter to selectively transmit data in response to a digital transmit data signal at said digital input; further characterized by: a terminal controller connected to a source of terminal input data and said modulator for providing a terminal request to send signal and said digital transmit data signal in response to operation of said source of terminal input data; said time mark signal being a time mark frame that includes an address field; and said low power controller being connected to said terminal controller and to said radio transmitter and monitoring data packets from said digital output for said time mark frame addressed to said low power controller and providing said frequency control signal to said tuner in response to information in said time mark frame, and powering up at least a portion of said radio transmitter in response to said terminal request to send signal, to maintain said portion of said radio transmitter in a powered up condition while said terminal controller is providing said digital transmit data signal, and to otherwise power down said portion of said radio transmitter.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.