Wireless communication apparatus using frequency hopping, and method of controlling the apparatus

• US 6,275,517 B1
• Filed: 03/19/1997
• Issued: 08/14/2001
• Est. Priority Date: 03/19/1996
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Izumi, Michihiro
• Primary Examiner(s): ZIMMERMAN, BRIAN A
• Application Number:
  US08/822,606
• Time in Patent Office: 1,609 Days
• Field of Search: 340/825.2, 340/825.14, 371/5.4, 371/22.36, 371/42, 371/47.1, 375/202, 375/354, 375/362, 375/364, 375/132-137, 370/503, 370/1
• US Class Current: 375/133
• CPC Class Codes: H04B 1/7156 Arrangements for sequence synchronisation
• CPC Class Codes: H04B 2001/71566 Tracking

Abstract

A wireless communication apparatus performs communication while changing frequencies according to a frequency hopping pattern, using a memory for storing a plurality of frequencies and designating a frequency to be used in the communication out of the stored plurality of frequencies stored in said memory means based on a first frequency hopping pattern. Depending on whether error is detected in information including data based on a second frequency hopping pattern and transmitted from another wireless communication apparatus, a frequency may be rewritten in the memory. Alternatively, time information in each received frame can be counted or not for use in reading out frequency information from a memory.

Claims

1. A wireless communication apparatus which performs communication while changing frequencies according to a frequency hopping pattern, said apparatus comprising:

memory arranged to store information related to a frequency hopping pattern used in communication;

a receiver, that receives information indicating a frequency and transmitted from another wireless communication apparatus;

an error detector, that detects an error in the information received by said receiver; and

a controller that controls said wireless communication apparatus to change a frequency not using the information received by said receiver but using the information that was stored in said memory before error detection by said error detector, when an error in the information received by said receiver is detected by said error detector during communication and to change a frequency using the information received by said receiver when no error is detected by said error detector.

2. The wireless communication apparatus according to claim 1, wherein said memory stores the information related to frequencies in correspondence with time information for frequency changeover.

3. The wireless communication apparatus according to claim 2, wherein said controller changes the frequency based on the time information.

4. The wireless communication apparatus according to claim 3, wherein said controller updates the information related to a frequency hopping pattern on the basis of the information received by said receiver, if said error detector does not detect an error in the received information.

5. The wireless communication apparatus according to claim 1, wherein the information received by said receiver includes frequency information indicating a next frequency to change.

6. The wireless communication apparatus according to claim 5, wherein said controller updates the information related to a frequency hopping pattern in said memory on the basis of the information received by said receiver, if said error detector does not detect an error in the received control information.

7. The wireless communication apparatus according to claim 5, wherein said controller includes a comparator arranged to compare the information received by said receiver to the information related to a frequency hopping pattern in said memory, and said controller updates the information related to a frequency hopping pattern in said memory in accordance with a comparison result by said comparison means.

8. The wireless communication apparatus according to claim 1, wherein the information received by said receiver includes first synchronizing information for frequency changeover.

9. The wireless communication apparatus according to claim 8, wherein said communication apparatus communicates while changing frequencies on the basis of the first synchronizing information.

10. The wireless communication apparatus according to claim 8, further comprising an output unit for outputting second synchronizing information for frequency changeover,

wherein said communication apparatus communicates by using the first synchronizing information or the second synchronizing information depending upon the error detection by said error detector.

11. A control method for controlling a wireless communication apparatus which stores a plurality of frequencies and performs communication while changing frequencies according to a frequency hopping pattern, said method comprising:

a storing step, of storing in a memory, information related to a frequency hopping pattern used in communication;

a reception step, of receiving information indicating a frequency and transmitted from another wireless communication apparatus;

an error detection step, of detecting an error in the information received in said reception step; and

a controlling step, of controlling the wireless communication apparatus to change a frequency not using the information received in said reception step but using the information that was stored in the memory before error detection in said error detection step, when an error in the information received in said reception step is detected in said error detection step during communication and to chance a frequency using the information received in said reception step when no error is detected by said error detector.

12. The control method according to claim 11, wherein information indicating the frequencies is stored in correspondence with time information for frequency changeover.

13. The control method according to claim 12, wherein, in said controlling step, the frequency is changed based on the time information.

14. The control method according to claim 13, wherein, in said controlling step, the information related to a frequency hopping pattern is updated on the basis of the information received in said reception step, if no error is detected in the received information in said error detection step.

15. The control method according to claim 11, wherein the information received in said reception step includes frequency information indicating a next frequency to change.

16. The control method according to claim 15, wherein, in said controlling step, the information related to a frequency hopping pattern is updated in the memory on the basis of the information received in said reception step, if no error is detected in the received control information in said error detection step.

17. The control method according to claim 15, wherein said controlling step further comprises a comparing step, of comparing the information received in said reception step to the information related to a frequency hopping pattern,

wherein the information related to a frequency hopping pattern is updated on the basis of the information in accordance with a comparison result obtained in said comparing step.

18. The control method according to claim 11, wherein the information received in said reception step includes first synchronizing information for frequency changeover.

19. The control method according to claim 18, wherein, in said communication step, communication is performed while changing frequencies on the basis of the first synchronizing information.

20. The control method according to claim 18, further comprising an output step, of outputting second synchronizing information for frequency changeover,

wherein communication is performed by using the first synchronizing information or the second synchronizing information depending upon the error detection in said error detection step.

21. A wireless communication apparatus performing communication by using a communication frame while changing frequencies, said apparatus comprising:

a receiver, arranged to receive time information for changing a frequency;

memory arranged to store frequency information in accordance with time information;

a counting unit that counts every communication frame and generates time information;

an error determiner, that determines whether or not there is an error in the time information received by said receiver; and

an output unit that outputs the frequency information from said memory in correspondence with time information outputted from said counting unit,

wherein said counting unit generates time information using the time information received by said receiver when an error is not detected by said error determiner, or generates time information not using the time information received by said receiver when an error is detected by said error determiner.

22. The wireless communication apparatus according to claim 21, wherein the other wireless communication apparatus also transmits frequency information to be used in the next communication frame, said receiver also receives the frequency information, and said error determiner also determines whether or not there is an error in the frequency information, and

wherein said output unit outputs the received frequency information to said memory if said error determiner determines that there is no error in the frequency information received by said receiver.

23. The wireless communication apparatus according to claim 21, wherein the other wireless communication apparatus also transmits frequency information to be used in the next communication frame, and said receiver also receives the frequency information, and said error determiner also determines whether there is an error in the frequency information or not, and

said wireless communication apparatus further comprises a comparator unit arranged to receive the frequency information, which has been determined that there is no error in it by said error determiner, to the frequency information, stored in said memory, corresponding to the output value from said counting unit, and an over-writer that writes over the frequency information received by said receiver and the frequency information corresponding to the output value from said counting unit in accordance with a comparison result provided by said comparator unit.

24. The wireless communication apparatus according to claim 21, wherein the other wireless communication apparatus transmits a synchronizing signal having a predetermined pattern for achieving frame synchronization at a predetermined position in a communication frame, and said receiver receives the synchronizing signal, and

said wireless communication apparatus further comprises a clock signal generator that generates a clock signal synchronized with a timing at which said synchronizing signal is received and input means for inputting the clock signal to said counting unit.

25. The wireless communication apparatus according to claim 24, wherein said clock signal generator has a synchronization locker and generates the clock signal regardless of whether the synchronizing signal is received or not.

26. The wireless communication apparatus according to claim 25, wherein said synchronization locker generates the clock signal when a time period corresponding to one communication frame elapses.

27. The wireless communication apparatus according to claim 24, wherein said clock signal generator includes:

a detector, arranged and constructed to detect the synchronizing signal;

a first counter, which is initialized at a time of detection of the synchronizing signal and outputs a timing pulse when a time period corresponding to one communication frame elapses;

a second counter, that generates a pulse at a position where the synchronizing signal is detected by said detector and outputs a frame position signal indicating a position of a communication frame when a time period corresponding to one communication frame elapses; and

a selector, arranged to select the frame position signal as the clock signal if said detector detects the synchronizing signal when the frame position signal is outputted and to select the output from the first counter as the clock signal if said detector fails to detect the synchronizing signal for a predetermined number of times consecutively when the frame position signal is outputted.

28. The wireless communication apparatus according to claim 21, wherein said output unit reads the frequency information, corresponding to a value which is obtained by adding a predetermined value to the output value from said counting unit, from said memory.

29. The wireless communication apparatus according to claim 28, wherein said output unit reads the frequency information, corresponding to a value which is obtained by adding a value predetermined for each communication channel to the output value from said counting unit, from said memory.

30. The wireless communication apparatus according to claim 29, wherein said communication channel includes a control channel, audio channel, and data channel.

31. A control method for controlling a wireless communication apparatus performing communication by using a communication frame while changing frequencies, said method comprising:

a reception step, of receiving time information for changing a frequency;

a counting step, of counting using a counter in every communication frame and generating time information;

an error determination step, of determining whether or not there is an error in the time information received in said reception step; and

an outputting step, of outputting the frequency information in correspondence with time information outputted from the counter,

wherein, in said counting step, time information is generated using the time information received in said reception step when an error is not detected in said error determination step, or not using the time information received in said reception step when an error is detected in said error determination step.

32. The control method according to claim 31, wherein the other wireless communication apparatus also transmits frequency information to be used in the next communication frame, the frequency information is received in said reception step, and it is determined in said error determination step whether or not there is an error in the frequency information, and

wherein said control method further comprises a second writing step, of writing to a memory the frequency information in correspondence with the output value from the counter if it is determined in said determination step that there is no error in the frequency information received in said reception step.

33. The control method according to claim 31, wherein the other wireless communication apparatus also transmits frequency information to be used in the next communication frame, the frequency information is received in said reception step, and it is determined in said error determination step whether or not there is an error in the frequency information, and

wherein said controlling method further comprises a comparison step, of comparing the frequency information, which is determined in said determination step not to contain an error, to the frequency information, stored in the memory, corresponding to the output value from the counter, and a writing-over step, of writing over the frequency information received in said reception step and the frequency information corresponding to the output value from the counter in accordance with a comparison result performed in said comparison step.

34. The control method according to claim 31, wherein the other wireless communication apparatus transmits a synchronizing signal having a predetermined pattern for achieving frame synchronization at a predetermined position in a communication frame, and in said reception step, the synchronizing signal is received, and

wherein said control method further comprises a generation step of generating a clock signal synchronized with a timing at which said synchronizing signal is received, and an input step, of inputting the clock signal to the counter.

35. The control method according to claim 34, wherein said generation step further comprises a synchronization locking step, in which the clock signal is generated regardless of whether the synchronizing signal is received or not.

36. The control method according to claim 35, wherein, in said synchronization locking step, the clock signal is generated when a time period corresponding to one communication frame elapses.

37. The control method according to claim 34, wherein said generation step further includes:

a detecting step, of detecting the synchronizing signal;

a timing pulse output step, of outputting a timing pulse when a time period corresponding to one communication frame elapses from a time of detection of the synchronizing signal;

a frame position signal output steps of generating a pulse at a position where the synchronizing signal is detected in said detecting step and outputting a frame position signal indicating a position of a communication frame when a time period corresponding to one communication frame elapses; and

a selection step, of selecting the frame position signal as the clock signal if the synchronizing signal is detected in said detecting step when the frame position signal is outputted, or the timing pulse as the clock signal if it is failed to detect the synchronizing signal in said detecting step for a predetermined number of times consecutively when the frame position signal is outputted.

38. The control method according to claim 31, wherein, in said reading step, the frequency information corresponding to a value which is obtained by adding a predetermined value to the output value from the counter is read from the memory.

39. The control method according to claim 38, wherein, in said reading step, the frequency information which is obtained by adding a predetermined value for each communication channel to the output value from the counter is read from the memory.

40. The control method according to claim 39, wherein said communication channel includes a control channel, audio channel, and data channel.

41. A wireless communication apparatus performing communication by using a communication frame while changing frequencies, said apparatus comprising

a receiver, arranged to receive information, corresponding to a frequency;

memory arranged to store information in correspondence with frequency information;

a counting unit that counts every communication frame and generates information corresponding to a frequency;

an error determiner, that determines whether or not there is an error in the information received by said receiver; and

an output unit that outputs the frequency information in correspondence with information outputted from said counting unit,

wherein said counting unit generates information using the information received by said receiver when an error is not detected by said error determiner, or generates information not using the information received by said receiver but using the information stored in said memory before error detection by said error determiner when an error is detected by said error determiner.

42. A control method for controlling a wireless communication apparatus performing communication by using a communication frame while changing frequencies, said method comprising:

a reception step, of receiving information, corresponding to a frequency;

a counting step, of counting using a counter in every communication frame for generating information corresponding to a frequency;

an error determination step, of determining whether or not there is an error in the information received in said reception step; and

an outputting step, of outputting the frequency information in correspondence with the information outputted from the counter,

wherein, in said counting step, the information is generated using the information received in said reception step when an error is not detected in said error determination step, or not using the information received in said reception step but using the information stored before error determination in said error determination step when an error is detected in said error determination step.

43. A wireless communication apparatus performing communication by using a communication frame while changing frequencies, said apparatus comprising:

reception means for receiving time information whose value changes for every communication frame transmitted from another wireless communication apparatus;

memory means for storing frequency information assigned to respective time information;

counting means for counting every communication frame and generating time information;

determination means for determining whether or not there is an error in the time information received by said reception means;

writing means for writing the time information received by said reception means to said counting means if said determination means determines that there is no error in the received time information;

continuing means for making said counting means continue counting if said determination means determines that there is an error in the received time information; and

reading means for reading the frequency information from said memory means on the basis of an output value from said counting means,

wherein the other wireless communication apparatus transmits a synchronizing signal having a predetermined pattern for achieving frame synchronization at a predetermined position in a communication frame, and said reception means receives the synchronizing signal, and said wireless communication apparatus further comprises generation means for generating a clock signal synchronized with a timing at which said synchronizing signal is received and input means for inputting the clock signal to said counting means,

wherein said generation means includes;

detecting means for detecting the synchronizing signal;

a first counter which is initialized at a time of detection of the synchronizing signal and outputs a timing pulse when a time period corresponding to one communication frame elapses;

a second counter for generating a pulse at a position where the synchronizing signal is detected by said detecting means and outputting a frame position signal indicating a position of a communication frame when a time period corresponding to one communication frame elapses; and

selection means which selects the frame position signal as the clock signal if said detecting means detects the synchronizing signal when the frame position signal is outputted and selects the output from the first counter as the clock signal if said detecting means fails to detect the synchronizing signal for a predetermined number of times consecutively when the frame position signal is outputted.

44. A control method for controlling a wireless communication apparatus performing communication by using a communication frame while changing frequencies, said method comprising:

a reception step of receiving time information whose value changes for every communication frame transmitted from another wireless communication apparatus;

a counting step of counting every communication frame and generating time information;

a determination step of determining whether or not there is an error in the time information received at said reception step;

a writing step of writing the time information received at said reception step to a counter if it is determined at said determination step that there is no error in the received time information;

a continuing step of continuing the counting at said counting step if it is determined at said determination step that there is an error in the received time information; and

a reading step of reading the frequency information from a memory for storing frequency information in correspondence with respective time information on the basis of an output value from the counter,

wherein the other wireless communication apparatus transmits a synchronizing signal having a predetermined pattern for achieving frame synchronization at a predetermined position in a communication frame, and at said reception step, the synchronizing signal is received, and said control method further comprises a generation step of generating a clock signal synchronized with a timing at which said synchronizing signal is received and an input step of inputting the clock signal to the counter,

wherein said generation step includes;

a detecting step of detecting the synchronizing signal;

a timing pulse output step of outputting a timing pulse when a time period corresponding to one communication frame elapses from a time of detection of the synchronizing signal;

a frame position signal output step of generating a pulse at a position where the synchronizing signal is detected at said detecting step and outputting a frame position signal indicating a position of a communication frame when a time period corresponding to one communication frame elapses; and

a selection step of selecting the frame position signal as the clock signal if the synchronizing signal is detected at said detecting step when the frame position signal is outputted, or the timing pulse as the clock signal if it is failed to detect the synchronizing signal at said detecting step for a predetermined number of times consecutively when the frame position signal is outputted.