CA2124882C - Interface protocol method and apparatus for use in a frequency hopping radio system - Google Patents

Interface protocol method and apparatus for use in a frequency hopping radio system Download PDF

Info

Publication number
CA2124882C
CA2124882C CA002124882A CA2124882A CA2124882C CA 2124882 C CA2124882 C CA 2124882C CA 002124882 A CA002124882 A CA 002124882A CA 2124882 A CA2124882 A CA 2124882A CA 2124882 C CA2124882 C CA 2124882C
Authority
CA
Canada
Prior art keywords
master
slave
cycle
channel
radio transmitter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
CA002124882A
Other languages
French (fr)
Other versions
CA2124882A1 (en
Inventor
Michael B. Ashdown
Philip Alan Young
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
VTech Communications Ltd
Original Assignee
VTech Communications Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by VTech Communications Ltd filed Critical VTech Communications Ltd
Publication of CA2124882A1 publication Critical patent/CA2124882A1/en
Application granted granted Critical
Publication of CA2124882C publication Critical patent/CA2124882C/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B1/00Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69Spread spectrum techniques
    • H04B1/713Spread spectrum techniques using frequency hopping
    • H04B1/7156Arrangements for sequence synchronisation
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B1/00Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69Spread spectrum techniques
    • H04B1/713Spread spectrum techniques using frequency hopping
    • H04B1/7143Arrangements for generation of hop patterns
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B1/00Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69Spread spectrum techniques
    • H04B1/713Spread spectrum techniques using frequency hopping
    • H04B1/715Interference-related aspects
    • H04B2001/7154Interference-related aspects with means for preventing interference
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B1/00Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69Spread spectrum techniques
    • H04B1/713Spread spectrum techniques using frequency hopping
    • H04B1/7156Arrangements for sequence synchronisation
    • H04B2001/71563Acquisition

Abstract

A method of communicating between two or more radios each capable of transmitting and receiving signals between one another on two or more radio channels wherein the radios hop from channel to channel in a pseudo-random sequence. The method comprises establishing hop synchronization between the radios utilizing a first cycle and operating the radios in a communication mode utilizing a second cycle. The first cycle is shorter than the second cycle so as to facilitate rapid synchronization while preserving the benefits and security obtained through the use of longer cycle length during communication mode.

Description

1. Field Of The Invention The present invention relates in general to a transmission and reception protocol and, in particu-lar, to a method of communicating between two or more radio transmitter/receivers utilizing a first pseudo-random cycle fox synchronization and a second pseudo-random cycle for communication.
2. Background Art Some radio transmitter/receivers, such as some cordless telephones, citizen band radios and the like, utilize spread spectrum technology. One type of spread spectrum communication is called frequency hopping, wherein each associated radio transmitter/receiver hops from channel to channel in a psuedo random sequence. The benefits of spreading transmission among numerous channels in the avail-able spectrum include evenly utilizing the available spectrum and avoiding "fast fading" concerns.
Given the proliferation of this type of radio, particularly cordless telephones, an infinite number of channels is desirable to achieve minimal inter-ference. However, due to regulations, available spectrum and radio characteristics, this number is relatively restricted. Within this relatively restricted number of channels it would be optimal to select each channel in a truly random fashion.
However, it is clear that if selection were truly random it would not be practical to synchronize the channel selection at the receiver and the transmit-ter, hence some form of pseudo-random channel selec-tion is used.

~1~~8~j It is a characteristic of pseudo-random sequences that after a finite number of selections the se-quence will repeat. In order to approximate a truly random sequence the repeat period, or "cycle," of the pseudo-random sequence needs to be very long.
The result of all these constraints has been radio transmitter/receivers which hop over typically dozens of channels using pseudo-random sequences with very long cycle times.
Where pseudo-random cycle times are very long, synchronization of two radio transmitter/receivers becomes difficult. One approach has been to provide additional information, such as a small number of designated control channels upon which a "master"
radio always transmits synchronization information to control a "slave" radio. Thus, an unsynchronized slave radio merely needs to sit and Wait on a con-trol channel for the master radio to hop onto the channel and transmit the synchronization informa-tion. This approach assumes that communication is continuous and only the master initiates communica-tions. However, particularly in the case of cord-less telephones, these assumptions are invalid. In fact, cordless telephones communicate at irregular, infrequent intervals and communication may be initi-ated by either the master (base unit) or the slave (handset).
It is thus an object of the present invention to provide a quick method of establishing synchroniza-tion between a master radio transmitter/receiver and one or more slave radio transmitter/receivers with-out the need for extended transmission periods by ~12~~~~
the master radio transmitter/receiver.
It is an associated object of the present inven-tion to provide two pseudo random codes for generat-ing the hopping cycles, wherein the one cycle used while the radios are idle -- and only intermittently transmitting -- is much shorter than the other, which is utilized during continuous communications to achieve the full benefit of spread spectrum technology.
These and other objects of the invention will become apparent in light of the attached specifica-tion and claims.
A preferred embodiment of the present invention comprises a method of communicating between two or more radio transmitter/receivers one of which may be the "master" transmitter/receiver, while the remain-ing one or more are '°slave" transmitter/receivers.
This method is particularly applicable to an embodi-ment wherein the radio transmitter/receivers are capable of transmitting and receiving signals on two or more radio channels while hopping from channel to channel in a pseudo-random sequence.
The method comprises establishing synchronization between the radio transmitter/receivers such that they are hopping from channel to channel in synchro-nization with one another utilizing a first cycle.
The method further comprises operating the radio transmitter/receivers in a communication mode where-in the radio transmitter/receivers hop from channel to channel in synchronization with one another utilizing a second cycle.

~1~488~
The first cycle, which may be generated using a first cycle code, is shorter than the second cycle, which may be generated using a second cycle code, so as to facilitate rapid synchronization while pre-serving the benefits and security obtained through the use of a longer length cycle during communica-tion mode.
In a preferred embodiment, one radio transmit ter/receiver will request a communication link while in the first cycle, thus causing the radio transmit-ter/receivers to switch from the first cycle to the second cycle as the radio transmitter/receivers begin to operate in communication mode.
In a preferred embodiment, establishing and main-taining synchronization between the radio transmit-ter/receivers includes determining whether the slave has lost synchronization with the master. This determination is made by transmitting from the master to the slave a sync marker at regular prede-termined times while each transmitter/receiver hops from channel to channel using the first cycle. The slave listens at the predetermined time for the incoming sync marker transmitted by the master while hopping from channel to channel using the first cycle. If the sync marker is received the slave resets an idle sync interval timer synchronization is deemed to exist. However, if the slave fails to receive the sync marker at the predetermined time, the slave deems synchronization to have been lost.
After recognizing that synchronization has been lost the slave transmits to the master a request for synchronization.

~124~8~
The slave transmits the request to synchronize to the master utilizing a third cycle. This third cycle, in a preferred embodiment, comprises Cycling through the first cycle backward and at twice the hopping rate of the first cycle. In a preferred embodiment this is achieved by calculating the values which the first cycle will take and storing these values in a look-up table so as to facilitate the backward cycling as required by the third cycle.
The master receives this request while listening for incoming messages from the slave while the master itself is hopping from channel to channel using the first cycle. In this manner the cycles executed by the slave and master will intersect.
Upon detecting an incoming request for sync message from the slave, the master transmits a sync message to the slave. In a preferred embodiment, the master continuously transmits the sync marker for at least two hopping cycles plus two additional hops in the first cycle.
The slave having paused upon completing transmis-sion of the request for sync message using the third cycle listens for the sync message which when de-tected is captured. The slave thus synchronizes itself to the master utilizing the received sync message. In a preferred embodiment, after receiving the sync message, the slave begins to hop substan-tially in sync with the master and immediately listens for a subsequent sync marker transmitted from the master so it can fine tune the synchroniza-tion between the master and the slave.
One advantage of the present method for syschroni-zation is that it requires only intermittent trans-missions between master and slave, thus spectrum utilization is substantially reserved for communica-tion mode.
Fig. 1 of the drawings is a flow diagram of one potential system in which the present method may be utilized;
Fig. 2 of the drawings is a flow diagram of the method of communication;
Fig. 3 of the drawings is a flow diagram synchro-nization step showing, in part, the master radio transmitter/receiver activity; and Fig. 4 of the drawings is a flow diagram, synchro-nization step showing, in part, the master slave activity.
While this invention is' susceptible of embodiment in many different forms and in many different sys-tems, there is shown in the drawings and will herein be described in detail, one specific embodiment in one exemplary system with the understanding that the present disclosure is to be considered as an exem-plification of the principles of the invention and is not intended to limit the invention to the embod-iaants illustrated.
The m~thod of communicating between two or more radio transmitter/receivers disclosed in the present application is for use in a system like the one shown in Fig. 1 of the drawings. Cordless tele-phones, like the one shown in Fig. 1, typically have a base unit and at least one portable unit. The base unit and at least one portable unit communicate with one another over radio frequencies. Both the base unit and each handset are capable of transmit-ting and receiving signals between one another on two or more radio channels. Some of these cordless telephones, such as cordless telephone 10 utilize frequency hopping, which involves hopping from channel to channel, such that transmission and reception occur only on the current channel, which is utilized only for a short period of time (on the order of ten milliseconds).
Cordless telephone 10 operates in communication mode 20 wherein base unit 11 and handset 12 hop from channel to channel in synchronization with one another while communicating over an open communica-tions channel 13. Ideally, a frequency hopping communication system, like cordless telephone 10, utilizes an infinite number of transmission chan-nels, which are addressed in a totally random manner so as to provide better transmission characteristics and even utilization of the frequency spectrum. The number of available channels, however, is typically restricted by governmental regulation, the available spectrum and radio frequency characteristics, such that there are considerably less than an infinite number of channels available. In a preferred embod-iment, cordless telephone 10 utilizes sixty-four transmission channels, however, a different number of channels may be utilized realizing that the fewer the number of channels the less the benefit achieved.
Accessing the available transmission channels in a 212188?
totally random manner is impractical. If frequency hopping were truly and totally random, base unit 11 and handset 12 could never be synchronized and thus could never communicate. Accordingly, frequency hopping radios utilize pseudo-random number genera-tors to determine the hop sequence such that the hop sequence appears to be non-repetitive by utilizing a lengthy sequence. However, the length may frustrate any attempts at synchronization.
Cordless telephone 10 utilizes a method for commu-nicating between base unit 11 and handset 12 wherein during communication mode (i.e, a voice conversation or data transmission) the hopping sequence is de-rived utilizing a second cycle code.
Cordless telephone 10 operates predominantly in idle mode 30 wherein no conversation occurs and thus there is no need for a continually open communica-tion channel. In reality, actual communication is very irregular and generally quite infrequent.
Furthermore, given spectrum utilization concerns --particularly in light of the proliferation of cord-less telephones, citizen band radios and like --idle mode 30 should contain no continuously open communication channel. However, during idle mode 30, base unit 11 and handset 12 must be in sync, such that when a user desires to make a call or a call is received on the telephone line, cordless telephone 10 can respond quickly and appropriately by switching into communication mode 20.
Establishing and maintaining synchronization between base unit 11 and handset 12 must occur while base unit 11 and handset 12 are frequency hopping 2.2488 and not continually transmitting. It would be unrea-sonable to wait sixteen months for the second cycle to repeat such that base unit 11 and handset 12 can be synchronized. Other alternatives such as main-taining an open communication channel or utilizing expensive clocks are either unreasonable or too expensive. Thus, the present method utilizes a first cycle during idle mode 30, wherein the first cycle is shorter than the second cycle so as to facilitate rapid synchronization. The second cycle, as described above, is utilized during communica-tion mode 20 so as to preserve the benefits obtained through the use of longer cycle length.
The first cycle comprises the values generated by a short cycle code. In a preferred embodiment, the short cycle code is derived from feedback shift registers using a 6th order irreducible polynomial to determine the feedback connections. This ar-rangement affords 26-1 addresses or 63. This in combination with a zero address allows the first cycle to address the available channels. The first cycle is thus much shorter than the second cycle and provides for easier synchronization of handset 12, the slave, to base unit 11, the master.
It should be noted that the only constraint on the number of transmission channels versus the first and s~cond cycle codes is that the number of transmis-sion channels be less than or equal to 2n, where n is the order of the short cycle code (first cycle) .
The number of transmission channels need not be a power of two, because tricks can be played with the sequence generators to provide the necessary num-2124~8~
bers.
The preferred embodiment of the method utilizes a third cycle while attempting to regain synchroniza-tion. The values for the first cycle are calculated off-line and stored into a look-up table, such that third cycle, which merely steps through the first cycle backward and at twice the hopping rate uti-lized in the first cycle, can be generated from this look-up table.
Handset 12 must synchronize to base unit 11 on power up and also when sync is lost. The method for synchronizing~handset 12 to base unit 11 discussed assumes base unit 11 to be considered the master and handset 12 the slave. This method is depicted in Figs. 3 and 4. Fig. 3 shows the process loop the master, i.e. base unit 11, follows during idle mode 30. Base unit 11 is powered up in step 101 setting its counters and,variable, and seeding the first and second cycles such that they can both begin to cycle. Once the initialization has finished, the main cycle of idle mode 30 begins.
The default for base unit 11 is listening for messages, step 102, while frequency hopping from channel to channel in first cycle. Steps 102, 103, 104 and 105 are shown as separate steps merely for explanatory purposea, in fact, these ~~steps~~ occur simultaneously in real time while listening on the channels dictated by the first cycle. While hopping in first cycle, the second cycle continues to be generated although it goes unused until communica-tion mode 20 is entered. While listening for mes-sage, step 102, base unit 11 is determining whether a message has been received, step 103. Step 103 includes reviewing any received message to determine if it was sent by an authorized handset, such as handset 12, such that messages from unauthorized handsets are not acted upon.
While listening for messages, step 102, base unit 11 is watching to see if the IDLE SYNC INTERVAL has timed-out, step 104. The value of IDLE SYNC INTER-VAL depends upon the frequency tolerance of the master oscillator (not shown) found within base unit 11. Base unit 11 merely continues to listen for messages until the interval has passed. However, once the interval passes, base unit 11 continues onto step 108, wherein base unit il transmits an IDLE-SYNC message on the current channel as deter-mined by the first cycle for eight successive hops in a preferred embodiment. After transmitting the IDLE_SYNC message, base unit il returns to listen for messages in step 102.
Fig. 4 shows the processing loop the slave, i.e.
handset 12, follows during idle mode 30. Handset 12 is powered up in step 201 setting its counters and variables, and seeding the first and second cycles such that they~can both begin to cycle. Once the initializatian has finished, handset 12 will seek to immediately attempt to synchronize to base unit il.
This is necessary because, base unit 11 and handset 12 seed the first and second cycles with different seeds and thus they are unlikely to be in synchroni-zation.
Handset 12 first transmits a REQDEST FOR SYNC
message to base unit 11, step 207. In a preferred ~~~~~8 embodiment, step 207 comprises the handset 12 trans-mitting the REQUEST FOR SYNC message three times per hop, with handset 12 hopping in a third cycle. This third cycle, as mentioned above, may involve step-ping backward through the first cycle or alterna-tively operate in another mode. In this embodiment, the third cycle is run at twice the hop rate at which the first and second cycles are run or five milliseconds per hop. Thus, while base unit 11 is listening in step 102 hopping in the first cycle, handset 12 is hopping in the reverse of the first cycle at twice the rate -- i.e. the third cycle.
This guarantees that base unit 11 will have two opportunities to receive at least one REQUEST FOR SYNC message.
In a preferred embodiment, the REQUEST FOR SYNC
message includes -- beside the handset ID code --the channel upon which handset 12 will stop and listen for the LONG CYCLE SYNC message to be sent by base unit 11.
The LONG CYCLE SYNC message contains the position of base unit 11 within the first and second cycles during each hop, such that as base unit 11 continues through the first cycle it continuously updates the LONG_CYCLE_SYNC message to reflect the current position for both cycles. Returning to Fig. 3, wherein base unit 11 having received a REQUEST FOR SYNC message in listening step 102 and receiving step 103 detects the message as a REQUEST_FOR_SYNC message, step 105. This causes base unit 11 to transmit the LONG CYCLE SYNC message to handset 12, step 107. This transmission occurs 212~~82 in the first cycle and, in a preferred embodiment, base unit 11 transmits the LONG CYCLE SYNC message throughout two passes through the first cycle plus two hops to guarantee that handset 12 receives the LONG CYCLE SYNC message, step 209. After base unit 11 completes step 107, it will transmit IDLE_SYNC
message, step 108.
Handset 12 waits on the selected frequency for sufficient time for base unit il to complete the first cycle twice. If the LONG CYCLE_SYNC message is received during the time, handset 12 immediately loads the location of base unit 11 in both the first and second cycles into the first and second cycle code generators respectively, step 210. Handset 12 then begins hopping on the next channel in the first cycle listening for an IDLE_SYNC message in step 211. Step 211 allows handset 12 to fine tune the synchronization by determining the exact receipt time of the IDLE SYNC message sent by base unit (step 108) and resetting its frame alignment and IDLE SYNC INTERVAL timer accordingly, shown in steps 212 and 213. Thereafter handset 12 continues into the main loop for idle mode 30.
This method of synchronization could be used while in the second cycle, realizing, however, that the timing required for this approach would be greater than that required by the approach described above.
Furthermore, it should be noted that in communica-tion mode 20, wherein an open channel continually exists, synchronization is maintained by utilizing sync message intenaixed within the voice and/or data packets.

Idle mode 30 main loop of handset 12 is almost identical to that of base unit 11. The default for handset 12 is listening for messages, step 202 while frequency hopping from channel to channel in the first cycle. Steps 202, 203, 204 and 205 are shown as separate steps merely for explanatory purposes, in fact, these "steps" occur simultaneous-ly in real time while listening on the channels dictated by the first cycle. While hopping in first cycle, the second cycle continues to be generated though not used until communication mode 20 is entered. While listening for messages, step 202, handset 12 is determining whether a message has been received, step 203. Step 203 includes reviewing any received message to determine if it was sent by an authorized master, such as base unit 11.
While listening for messages in step 202, handset 12 watches to see if the IDLE SYNC INTERVAL has timed-out, step 204. The value of IDLE SYNC INTER-VAL depends upon the frequency tolerance of the master oscillator (not shown) found within base unit 11. diandset 12 merely continues to listen for messages until the interval has passed.
If handset 12 has not received the IDLE SYNC
message before the IDLE-SYNC_INTERVAL times out, step 204, handset 12 recognizes that synchronization has been lost and begins the REQUEST FOR SYNC trans-mission, step 2o7.
The purpose of idle mode 30 is to maintain syn-chronization such that when communication is desired a switch to communication mode 20 can be almost instantaneous. Thus, by listening for IDLE-SYNC

212~~sz messages and responding appropriately, when base unit 11 or handset 12 receives a process message in steps 103 and 203, respectively, rather than a synchroni-zation message, each can process the message, step 106, after which they both switch to the second cycle so as to secure communication in communication mode 20.
The foregoing description and drawings merely explain and illustrate the invention and the inven-tion is not limited thereto, except insofar as the appended claims are so limited and as those skilled in the art who have the disclosure before them will be able to make modification and variations therein without departing from the scope of the invention.

Claims (15)

1. A method of communicating between two or more radio transmitter/receivers, for use in a system having:
- two or more radio transmitter/receivers which communicate with one another, - each of the radio transmitter/receivers being capable of transmitting and receiving signals between one another on two or more radio channels wherein the radio transmitter/receivers hop from channel to channel in a pseudo-random sequence;
the method comprising the steps of:
- establishing synchronization between the radio transmitter/receivers whereby the radio transmitter/receivers are hopping from channel to channel in synchronization with one another utilizing a first cycle; and - operating the radio transmitter/receivers in a communication mode wherein the transmitter/receivers are hopping from channel to channel in synchronization with one another while in communication mode utilizing a second cycle;
- wherein the first cycle is shorter than the second cycle so as to facilitate rapid synchronization while preserving the benefits and security obtained through the use of longer cycle length during communication mode.
2. The invention according to Claim 1 wherein the invention further comprises the step of generating the first cycle using a first cycle code.
3. The invention according to Claim 1 wherein the invention further comprises the step of generating the second cycle.using a second cycle code.
4. The invention according to Claim 1 wherein the invention further comprises the step of switching from the first cycle to the second cycle when the radio transmitter/receivers begin to operate in communication mode.
5. The invention according to Claim 1 wherein one of the two or more radio transmitter/receivers is a master and the remaining radio transmitter/receivers are slaves, the step of establishing synchronization between the radio transmitter/receivers includes the sub-steps of:
a. determining whether the slave has lost synchronization with the master;
b. transmitting from the slave to the master a request to synchronize the master and slave upon losing synchronization between the master and the slave utilizing a third cycle;
c. receiving on the master an incoming request to synchronize the master and the slave;
d. transmitting from the master to the slave a sync message in response to the master detecting an incoming request to synchronize the master and slave; and e. synchronizing the slave to the master utilizing the sync message received by the slave.
6. A method for synchronizing a slave radio transmitter/receiver to a master radio transmitter/receiver, for use in a system having:
- a master radio transmitter/receiver and one or more slave radio transmitter/receivers each of which communicate with the master radio transmitter/receiver, - the master and slave radio transmitter/receivers being capable of transmitting and receiving signals between one another on two or more radio channels wherein the radio transmitter/receivers hop from channel to channel in a pseudo-random sequence, - operation among the master and slave transmitter/receivers take place using both a first cycle and a second cycle wherein the cycles correspond to the channel sequence, - the first cycle being utilized during synchronization of the master and a slave radio transmitter/receiver, - the second cycle being utilized during the communication mode between radio transmitter/receivers, ~
the method comprising the steps of:
a. determining whether the slave has lost synchronization with the master;
b. transmitting from the slave to the master a request to synchronize the master and slave upon losing synchronization between the master and the slave utilizing a third cycle;
c. receiving on the master an incoming request to synchronize the master and the slave;
d. transmitting from the master to the slave a sync message in response to the master detecting the incoming request to synchronize the master and slave; and e. synchronizing the slave to the master utilizing the sync message received by the slave.
7. The invention according to Claim 6 wherein the step of determining loss of synchronization comprises the sub-steps of:
- transmitting from the master to the slave a sync marker at a predetermined time while hopping from channel to channel using the first cycle;
- listening on the slave at the predetermined time for the incoming sync marker transmitted by the master while hopping from channel to channel using the first cycle;
- resetting an idle sync interval timer in response to receiving the sync marker at the predetermined time; and - recognizing that synchronization has been lost upon failure to receive the incoming sync marker at the predetermined time.
8. The invention according to Claim 6 wherein the step of receiving includes the sub-step of listening on the master for the incoming request to synchronize while hopping from channel to channel using the first cycle.
9. The invention according to Claim 6 wherein the method further includes the step of stopping the slave on a selected channel after transmitting the request for synchronization and remaining on the selected channel until the slave receives the sync massage from the master.
10. The invention according to Claim 9 wherein the step of transmitting from the master to the slave occurs only on the selected channel while the master continues hopping from channel to channel using the first cycle.
11. The invention according to Claim 6 wherein the step of transmitting a sync message from the master to the slave continues hopping from channel to channel using the first cycle for at least one cycle.
12. The invention according to Claim 6 wherein the step of synchronizing includes the sub-steps of:
- deriving the position of the master within the first and second cycles from the sync message;
and - matching the position of the slave within the first and second cycles to the derived position of the master.
13. The invention according to Claim 12 wherein the step of synchronizing further includes the sub-step of receiving a sync marker on the slave from the master so as to fine tune the synchronization between the master and the slave.
14. The invention according to Claim 6 wherein the third cycle comprises the step of cycling through the first cycle backward and at twice the hopping rate of the first cycle, the first cycle being stored in a look-up table so as to facilitate the backward cycling.
15. A method for synchronizing a slave radio transmitter/receiver to a master radio transmitter/receiver, for use in a system having:
- a master radio transmitter/receiver and one or more slave radio transmitter/receivers which each communicate with the master radio transmitter/receiver, - the master and slave radio transmitter/re-ceivers being capable of transmitting and receiving signals between one another on two or more radio channels wherein the transmitter/receivers hop from channel to channel in a pseudo-random sequence, - operation among the master and slave transmitter/receivers take place using both a first cycle and a second cycle wherein the cycles correspond to the channel sequence, - the first cycle being utilized during synchronization of the master and a slave radio transmitter/receiver, - the second cycle being utilized during the communication mode between radio transmitter/receivers, the method comprising the steps of:
a. determining whether the slave has lost synchronization with the master, wherein the step includes the sub-steps of:
- transmitting from the master to the slave a sync marker at a predetermined time while hopping from channel to channel using the first cycle;
- listening on the slave at the predetermined time for the incoming sync marker transmitted by the master while hopping from channel to channel using the first cycle;
- resetting an idle sync interval timer in response to receiving the sync marker at the predetermined time;
- recognizing that synchronization has been lost upon failure to receive the incoming sync marker at the predetermined time;
b. transmitting from the slave to the master a request to synchronize the master and slave after recognizing that synchronization has been lost between the master and the slave utilizing a third cycle;
c. receiving on the master the incoming request to synchronize the master and the slave, wherein the step includes the sub-step of:
- listening on the master for the incoming request to synchronize the master and the slave while hopping from channel to channel using the first cycle;
d. transmitting from the master to the slave a sync message in response to the master detecting the incoming request to synchronize the master and the slave; and e. synchronizing the slave to the master utilizing the sync message received by the slave, wherein the step includes the sub-steps of:
- deriving the position of the master within the first and second cycles from the sync message;
and - matching the position of the slave within the first and second cycles to the derived position of the master.
CA002124882A 1993-06-02 1994-06-01 Interface protocol method and apparatus for use in a frequency hopping radio system Expired - Fee Related CA2124882C (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9311340.5 1993-06-02
GB9311340A GB2279850B (en) 1993-06-02 1993-06-02 Interface protocol method and apparatus

Publications (2)

Publication Number Publication Date
CA2124882A1 CA2124882A1 (en) 1994-12-03
CA2124882C true CA2124882C (en) 2000-10-24

Family

ID=10736480

Family Applications (1)

Application Number Title Priority Date Filing Date
CA002124882A Expired - Fee Related CA2124882C (en) 1993-06-02 1994-06-01 Interface protocol method and apparatus for use in a frequency hopping radio system

Country Status (3)

Country Link
US (1) US5586141A (en)
CA (1) CA2124882C (en)
GB (2) GB2313984B (en)

Families Citing this family (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2309357B (en) 1996-01-18 2000-08-16 Nokia Mobile Phones Ltd Communicating between base stations and cellular mobile phones
US6061409A (en) * 1996-06-27 2000-05-09 Matsushita Electric Industrial Co., Ltd. Synchronization recovery for a mobile telephone
KR100264862B1 (en) 1997-07-31 2000-09-01 윤종용 Orthogonal code hopping multiple access communication system
CA2300068A1 (en) * 1997-08-14 1999-02-25 Siemens Aktiengesellschaft Method and device for generating a carrier frequency
US7301986B2 (en) * 1997-09-15 2007-11-27 Andrzej Partyka Frequency hopping system for intermittent transmission
US6058137A (en) 1997-09-15 2000-05-02 Partyka; Andrzej Frequency hopping system for intermittent transmission
DE19755832A1 (en) * 1997-12-16 1999-06-17 Cit Alcatel Generation of frequency hopping sequence for radio communication
US6473412B1 (en) 1998-04-03 2002-10-29 Telefonaktiebolaget Lm Ericsson (Publ) Uncoordinated frequency hopping cellular system
US7224713B2 (en) 1998-04-09 2007-05-29 Andrzej Partyka Telemetry system with authentication
US6728293B1 (en) 1999-09-14 2004-04-27 Andrzej Partyka Hopping pattern generation method in frequency hopping system for intermittent transmission
US6870875B1 (en) 1999-09-30 2005-03-22 Andrzej Partyka Transmission of urgent messages in frequency hopping system for intermittent transmission
US6967974B1 (en) 1999-09-30 2005-11-22 Andrzej Partyka Transmission of urgent messages in telemetry system
US6731223B1 (en) 2000-01-15 2004-05-04 Andrzej Partyka Meshed telemetry system
US6894975B1 (en) 2000-01-15 2005-05-17 Andrzej Partyka Synchronization and access of the nodes in a communications network
US6925105B1 (en) 2000-05-01 2005-08-02 Andrzej Partyka Overhead reduction in system for intermittent transmission
US7209495B2 (en) 2000-09-28 2007-04-24 Andrzej Partyka Urgent messages and power-up in frequency hopping system for intemittent transmission
ATE468723T1 (en) * 2000-11-03 2010-06-15 Sony Deutschland Gmbh TRANSMIT POWER CONTROL FOR OFDM COMMUNICATION CONNECTIONS
GB0031619D0 (en) * 2000-12-27 2001-02-07 Koninkl Philips Electronics Nv Method and apparatus for synchronising frequency hopping transceivers
US7027418B2 (en) 2001-01-25 2006-04-11 Bandspeed, Inc. Approach for selecting communications channels based on performance
EP2224612A1 (en) 2003-01-31 2010-09-01 NTT DoCoMo, Inc. Radio system and method for simultaneous reception of signals
ATE433229T1 (en) * 2004-04-15 2009-06-15 Dsp Group Switzerland Ag DEVICE FOR USE IN A FREQUENCY HOPPING SYSTEM
US20090190214A1 (en) * 2008-01-29 2009-07-30 Nicholas Francis Borrelli Polarizing photorefractive glass
US8179595B2 (en) 2008-01-29 2012-05-15 Corning Incorporated Polarizing photorefractive glass
US8447252B2 (en) 2009-01-21 2013-05-21 Bandspeed, Inc. Adaptive channel scanning for detection and classification of RF signals
US8849213B2 (en) 2009-01-21 2014-09-30 Bandspeed, Inc. Integrated circuit for signal analysis
US8275017B2 (en) * 2009-02-05 2012-09-25 Modesat Communications Ou Method of packet transmission and reception of quadrature amplitude modulated signals in a frequency hopping radio system

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4193030A (en) * 1968-08-01 1980-03-11 International Telephone And Telegraph Corporation Frequency hopping communication system
US4355399A (en) * 1981-02-23 1982-10-19 Bell Telephone Laboratories, Incorporated Adaptive spread spectrum FH-MFSK transmitter and receiver
US4558453A (en) * 1981-12-16 1985-12-10 Harris Corporation Synchronization method and frequency hopping communication system
FR2552957B1 (en) * 1983-09-30 1986-07-25 Trt Telecom Radio Electr TRANSCEIVER STATION FOR A FREQUENCY ESCAPE INFORMATION TRANSMISSION SYSTEM
US5029180A (en) * 1989-03-23 1991-07-02 Echelon Systems Corporation Transceiver providing selectable frequencies and spreading sequences
FI86123C (en) * 1990-11-15 1992-07-10 Telenokia Oy RADIOSAENDARMOTTAGARSYSTEM.
US5144668A (en) * 1991-01-25 1992-09-01 Motorola, Inc. Signal overlap detection in a communication system
TW327488U (en) * 1991-05-29 1998-02-21 Video Tech Eng Digital cordless telephone apparatus
US5303260A (en) * 1993-01-06 1994-04-12 Unisys Corporation Method and circuit for compensating for oscillator drift in a spread-spectrum communication system
US5339331A (en) * 1993-09-09 1994-08-16 Lockheed Corporation Frequency hopping spread spectrum receiver
US5504750A (en) * 1994-08-01 1996-04-02 Motorola, Inc. Method and apparatus for a radio system operating on shared communication channels

Also Published As

Publication number Publication date
GB2279850B (en) 1998-01-28
GB2313984B (en) 1998-01-28
GB2279850A (en) 1995-01-11
GB9311340D0 (en) 1993-07-21
GB9716757D0 (en) 1997-10-15
GB2313984A (en) 1997-12-10
CA2124882A1 (en) 1994-12-03
US5586141A (en) 1996-12-17

Similar Documents

Publication Publication Date Title
CA2124882C (en) Interface protocol method and apparatus for use in a frequency hopping radio system
KR910007712B1 (en) Radio communication system using synchronous frequency hopping transmissions
CA1251262A (en) Rapid anti-jam frequency-hopping time synchronization
KR100313704B1 (en) Radio communications systems and methods for jittered beacon transmission
US4872205A (en) Radio communication system having autonomously selected transmission frequencies
US6028853A (en) Method and arrangement for radio communication
US5606560A (en) Between a base station and a portable device
JP3113416B2 (en) Cordless telephone configured to operate in a frequency hopping system
US4807248A (en) Automatic resynchronization technique
CA2157959C (en) Apparatus and method for obtaining synchronism between a base station and a portable unit arranged for operation in a frequency hopping system
US20040258136A1 (en) Fast synchronization for half duplex digital communications
JPS6027241A (en) Battery saving system of radio relay system
JPS58131829A (en) Radio relay system
WO1996025808A1 (en) Picking up of mobile stations from a direct mode channel
US7016316B2 (en) Synchronous TDD system
JP4361699B2 (en) Handset time synchronization for wireless telephone base stations
KR100615718B1 (en) Synchronization
CA2300068A1 (en) Method and device for generating a carrier frequency
EP1738480B1 (en) Device for use in a frequency hopping system
JP3443207B2 (en) Wireless communication system
JPH0946270A (en) Spread spectrum communication system, radio terminal equipment and its synchronization signal control method
EP1050981B1 (en) Flexible time slot for communication
JP2001016163A (en) Device and system for radio transmission
JPH06244792A (en) Tdma cordless telephone set
KR100473738B1 (en) Wireless Transceiver Synchronization Method and Apparatus in Cellular System

Legal Events

Date Code Title Description
EEER Examination request
MKLA Lapsed
MKLA Lapsed

Effective date: 20090601