Wireless communication system, apparatus, method and computer program product including timed beacon transmission control

• US 7,787,437 B2
• Filed: 02/03/2004
• Issued: 08/31/2010
• Est. Priority Date: 02/03/2003
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Sakoda, Kazuyuki
• Primary Examiner(s): Eng; George
• Assistant Examiner(s): Brandt; Christopher M
• Application Number:
  US10/500,591
• Publication Number:
  US 20050068934A1
• Time in Patent Office: 2,401 Days
• Field of Search: 370/328, 370/338, 370/345, 370/350, 370/312, 370/329, 370/348
• US Class Current: 370/350
• CPC Class Codes: H04L 5/0058 Allocation criteria
• CPC Class Codes: H04W 16/00 Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 56/002 Mutual synchronization
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

It is necessary to solve problems caused when constituting a communication system such as a radio LAN using an independent distributed type network without the controlling-controllable relationship of a master station and a slave station. In the radio communication system consisting of a plurality of communication stations having no relationship of a controlling station and a controllable station, each communication station transmits a beacon describing information on the network, thereby constituting a network. Through this beacon, it is possible to make a sophisticated judgment on the communication state in the other communication station.

Claims

1. A wireless communication system comprising:

a plurality of communication stations as part of an ad hoc network without a relationship of a control station and controlled stations, wherein

respective communication stations transmit beacons with information concerning a network described thereon with each other to configure said network without using an access point,

said information concerning a network including indications of beacons received from other communication stations that are part of said network,

a beacon transmitted from a local station includes neighboring communication station information pertaining to a reception time at said local station of a beacon transmitted from the neighboring communication station.

2. A wireless communication system according to claim 1, wherein said information concerning the network is information indicating whether local station is aware of the presence of beacons the respective stations transmitted.

3. A wireless communication system according to claim 1, wherein each of said communication stations transmits a beacon signal at a predetermined time period.

4. A wireless communication system according to claim 3, wherein each of said communication stations performs reception continuously over a time period longer than its own beacon transmission interval at least once at a predetermined time.

5. A wireless communication system according to claim 2, wherein said communication station, which became aware of a time at which an other station plans to transmit a beacon with reference to a clock value memorized in the local station, transmits information for prohibiting a neighboring station from transmitting data over a predetermined time period.

6. A wireless communication system according to claim 2, wherein said information indicating whether the local station is aware of the presence of a beacon signal the respective stations transmitted is information indicated by a relative time at which the local station transmits a beacon signal.

7. A wireless communication system according to claim 2, wherein each of said plurality of communication stations determines a beacon transmission timing of the local station based on information obtained from a beacon signal which the local station can receive from other station.

8. A wireless communication system according to claim 7, wherein each of said communication stations continues to receive a beacon from other station over a predetermined time period before starting transmission of a new beacon, it memorizes reception time information of a received beacon transmitted from other station as first information, and it shifts said information described in said received beacon indicating whether the local station is aware of a presence of beacon based upon said first information, and it memorize the shifted information as second information.

9. A wireless communication system according to claim 8, wherein said communication station extracts a reception timing of a beacon, which the local station or other station can receive, from said second information, and it determines a target interval, which an interval in which a beacon reception time space becomes a maximum beacon space, and it sets a beacon transmission timing of the local station to a central time of said target interval.

10. A wireless communication system according to claim 9, wherein each of said communication stations attempts to receive a signal transmitted from other station during a predetermined time period and it memorizes a time zone a beacon and other signal are received with a low frequency as third information.

11. A wireless communication system according to claim 10, wherein respective of said communication stations extracts each beacon space information, determines a target interval, which target interval corresponding to a time zone with a low frequency at which a signal obtained from said third information, and sets a beacon transmission timing of the local station to a central time of said target interval.

12. A wireless communication system according to claim 7, wherein respective of said communication stations which received an alteration request message of a beacon transmission timing from other station determines a new beacon transmission timing.

13. A wireless communication system according to claim 1, wherein said information concerning the network is information indicating whether the local station is in reception state in which a timing beacon signals is transmitted.

14. A wireless communication system according to claim 13, wherein said information indicative of whether the local station is in reception state in which the timing beacon signal is transmitted is information indicated by a relative time from a timing the local station transmits a beacon.

15. A wireless communication system according to claim 13, wherein a specific time zone in which said beacon signal is transmitted is set to a transmission prohibit interval.

16. A wireless communication system according to claim 1, wherein said beacon transmission timing of said communication stations within said network is delayed a predetermined target beacon transmission timing by a random time, and describe information indicative of a delayed amount in said beacon.

17. A wireless communication system according to claim 16, wherein said communication station, which became aware of a time at which an other station plans to transmit a beacon with reference to a clock value memorized in the local station, transmits information for prohibiting a neighboring station from transmitting data over a predetermined time period.

18. A wireless communication system according to claim 16, wherein when each of said communication systems receives a beacon from the other communication station, it calculates a target beacon transmission timing of said beacon transmission station from a beacon reception time in consideration of a time indicative of said delay amount.

19. A wireless communication system according to claim 18, wherein said communication station adjusts a clock of the local station in accordance with a timing of other station, when there is difference between a target beacon transmission timing of other station predicted from the clock value memorized in the local station and a target beacon transmission timing which results from subtracting a timing at an intentionally delayed beacon transmission time described in a beacon from which a beacon was actually received.

20. A wireless communication system according to claim 19, wherein said communication station adjusts a clock of the local station to a timing of other station, when the target beacon transmission timing of the beacon transmission station is delayed from the target beacon transmission time predicted by the local station.

21. A wireless communication system according to claim 16, wherein each of said communication stations describes the effect thereof in said beacon if said beacon transmission time is delayed due to an external primary factor when it transmits a beacon.

22. A wireless communication system according to claim 16, wherein said random time with which the beacon transmission timing is delayed from the target beacon transmission timing is given in the form of a pseudorandom sequence and the value of said pseudorandom sequence is transmitted as information indicative of a delayed amount described in said beacon.

23. A wireless communication system according to claim 22, wherein each of said communication stations memorizes the value of said pseudorandom sequence described in said beacon and calculates a next beacon transmission timing of said beacon transmission station by updating a pseudorandom sequence value of every predetermined period.

24. A wireless communication system according to claim 1, wherein a predetermined time period is set in which a beacon transmission station can transmit a packet with a priority after has transmitted said beacon signal.

25. A wireless communication system according to claim 24, wherein a time period is set in which each communication station transmit packet based upon predetermined contention control, after said predetermined time period in which said beacon transmission station can transmit a packet with a priority has expired.

26. A wireless communication system according to claim 25, wherein said communication station which communicates with said beacon transmission station can transmit a packet with a priority at said predetermined time period in which said beacon transmission station can transmit a packet with a priority.

27. A wireless communication system according to claim 24, wherein said communication station, which became aware of a time at which other station plans to transmit a beacon with reference to a clock value memorized in the local station, transmits information for prohibiting a neighboring station from transmitting data over a predetermined time period.

28. A wireless communication system according to claim 24, wherein each of said communication stations recognizes the state in which it does not receive a signal from other station over a predetermined time period calculated by a predetermined procedure before the local station transmits a packet, and it sets said predetermined time period to be short so it can transmit a packet with a priority.

29. A wireless communication system according to claim 28, wherein each of said communication stations recognizes the state in which it does not receive a signal from other station over a predetermined time period calculated by a predetermined procedure before the local station transmits a packet, and it sets said predetermined time period to be long only during said predetermined time period immediately after it received a beacon from other station.

30. A wireless communication system according to claim 28, wherein each of said communication stations transmits a transmission request signal and recognizes reception of a response to said transmission request signal before the local station transmits a signal.

31. A wireless communication system according to claim 30, wherein each of said communication stations does not carry out virtual carrier sense when it received the transmission request signal correctly and it carries out virtual carrier sense when it received the response to said transmission request signal correctly.

32. A wireless communication system according to claim 28, wherein it is determined by said communication station whether or not a media is clear over a time period corresponding to a stipulated maximum signal length before transmission, when it attempts to transmit a beacon signal immediately after it is changed from the sleep state to the active state.

33. A wireless communication system according to claim 28, wherein said communication station adds a unique preamble word to the beginning of a packet, and it also adds a mid-amble of a similar unique word to every predetermined payload length.

34. A wireless communication system according to claim 24, wherein said communication station, which transmit a stream of traffic extracts a plurality of time periods in which a beacon is not transmitted, and it transmits a beacon or a signal similar to the beacon in the extracted time period.

35. A wireless communication system according to claim 34, wherein said communication station transmits said signal similar to the beacon continuously or intermittently.

36. A wireless communication system according to claim 34, wherein each of said communication stations recognizes the state in which it does not receive a signal from other station over a predetermined time period calculated by a predetermined procedure before the local station transmits a packet, and it sets said predetermined time period to be short so it can transmit a packet with a priority.

37. A wireless communication apparatus operating in a decentralized distributed communication environment constructed such that respective communication stations transmit beacons indicative of information concerning a network with each other at a predetermined time space comprising:

communication means for transmitting and receiving wireless data in said decentralized distributed communication environment without an access point serving as a master control station;

beacon signal generating means for generating a beacon signal indicative of information concerning a local station;

beacon signal analyzing means for analyzing a beacon signal received from a neighboring station by said communicating means; and

timing control means for controlling a beacon transmission timing at which said communication means transmits beacons as part of an ad hoc network, said information concerning a network including indications of beacons received from other communication stations that are part of said network, wherein

a beacon transmitted from a local station includes neighboring beacon information pertaining to a reception time at said local station of a beacon transmitted from the neighboring communication station.

38. A wireless communication apparatus according to claim 37, wherein said information concerning the network written in the beacon generated from said beacon signal generating means is information indicating whether or not the local station is aware of a time at which a beacon signal is transmitted.

39. A wireless communication apparatus according to claim 37, wherein said timing control means transmits a beacon signal at a predetermined time space when a communication station joins a network.

40. A wireless communication apparatus according to claim 39, wherein said communication means performs reception continuously over a time period longer than its own beacon transmission interval at least once at a predetermined time.

41. A wireless communication apparatus according to claim 38, wherein said beacon signal generating means, which became aware of a time at which an other station plans to transmit a beacon with reference to a clock value memorized in the local station, transmits information for prohibiting a neighboring station from transmitting data over a predetermined period and energizes said communication means to transmit said beacon.

42. A wireless communication apparatus according to claim 38, wherein said information indicating whether or not the local station is aware of a time at which a beacon signal is transmitted is information indicated by a relative time between said time and a time at which the local station transmits a beacon signal.

43. A wireless communication apparatus according to claim 38, wherein each of said timing control means determines a beacon transmission time based on information obtained from a beacon signal, analyzed by said beacon signal analyzing means, from other station.

44. A wireless communication apparatus according to claim 43, wherein said timing control means continues to receive a beacon from said communication means over a predetermined time period before starting transmission of a new beacon, it holds reception time information of a received beacon transmitted from other station as first information and it shifts information described in said received beacon indicating whether or not the local station is aware of a time at which a beacon signal is transmitted based upon said information and it holds the shifted information as second information.

45. A wireless communication apparatus according to claim 44, wherein said communication station extracts a reception time of a beacon, which the local station or the local station and other station can receive, from said second information, it determines an interval in which a beacon reception time space becomes a maximum beacon space as a target interval and it sets a beacon transmission time of the local station to a central time of said target interval.

46. A wireless communication apparatus according to claim 45, wherein said timing control means attempts to receive a signal transmitted from other station by said communication means during a predetermined time period and it holds a time zone with a small frequency at which a beacon and other signal are received as third information.

47. A wireless communication apparatus according to claim 46, wherein said timing control means extracts each beacon space information, it determines an interval corresponding to a time zone with a small frequency at which a signal obtained from said third information as a target interval and sets a beacon transmission time of the local station to a central time of said target interval.

48. A wireless communication apparatus according to claim 43, wherein said timing control means determines a new beacon transmission time if said beacon signal analyzing means judges a beacon transmission time alteration request message from other station.

49. A wireless communication apparatus according to claim 37, wherein said information concerning the network described in a beacon generated from said beacon signal generating means is information indicating whether or not the local station is aware of a time at which a received beacon signal is transmitted.

50. A wireless communication apparatus according to claim 49, wherein said information indicative of whether or not the local station is aware of a time at which a received beacon signal is transmitted is information indicated by a relative time between said time and a transmission time of a beacon signal from the local station.

51. A wireless communication apparatus according to claim 49, wherein said specific time zone in which said beacon signal is transmitted is set to a transmission prohibit interval by information described in the beacon generated from said beacon signal generating means.

52. A wireless communication apparatus according to claim 37, wherein said timing control means delays said transmission time of a beacon signal transmitted from a communication station within said network from a predetermined target beacon transmission time by a random time and said beacon signal generating means describes information indicative of a delayed amount in said beacon.

53. A wireless communication apparatus according to claim 52, wherein said beacon signal generating means, which became aware of a time at which other station plans to transmit a beacon with reference to a clock value memorized in the local station, adds information for prohibiting a neighboring station from transmitting data over a predetermined period to a beacon and it energizes said communication means to transmit said resultant information.

54. A wireless communication apparatus according to claim 52, wherein when said communication means receives a beacon from other communication station, said timing control means calculates a target beacon transmission time from a beacon reception time in consideration of a time indicative of said delay amount.

55. A wireless communication apparatus according to claim 54, wherein said communication station adjusts a clock of the local station in accordance with a timing of other station when a neighboring station target beacon transmission time predicted from the clock value memorized in the local station and a target beacon transmission time of a beacon transmission station which results from subtracting a time at which a beacon was actually received and an intentionally delayed beacon transmission time described in a beacon are different from each other.

56. A wireless communication apparatus according to claim 55, wherein said communication station adjusts a clock of the local station in accordance with a timing of other station when the target beacon transmission time of the beacon transmission station is delayed from the target beacon transmission time predicted by the local station.

57. A wireless communication apparatus according to claim 52, wherein said beacon signal generating means describes a delay amount of a beacon transmission time in said beacon if said beacon transmission time is delayed due to an external primary factor when it transmits a beacon under control of said timing control means.

58. A wireless communication apparatus according to claim 52, wherein said random time with which the beacon transmission time is delayed from the target beacon transmission time is given in the form of a pseudorandom sequence and the state of said pseudorandom sequence is transmitted as information indicative of a delay amount described in said beacon.

59. A wireless communication apparatus according to claim 58, wherein said timing control means holds the state of said pseudorandom sequence described in said beacon and calculates the next beacon transmission time of said beacon transmission station by updating a pseudorandom sequence value of every predetermined period.

60. A wireless communication apparatus according to claim 37, wherein said timing control means sets a predetermined time period in which a beacon transmission station can transmit a packet with a priority after said communication means has transmitted said beacon signal.

61. A wireless communication apparatus according to claim 60, wherein said communication station sets a time period in which each communication station performs transmission based upon predetermined contention control after said predetermined time period in which said beacon transmission station can transmit a packet with a priority that has expired.

62. A wireless communication apparatus according to claim 61, wherein said communication station which communicates with said beacon transmission station can transmit a packet with a priority at said predetermined time period in which said beacon transmission station can transmit a packet with a priority.

63. A wireless communication apparatus according to claim 60, wherein said communication station, which became aware of approach of a time at which other station plans to transmit a beacon with reference to a clock value memorized in the local station, transmits information for prohibiting a neighboring station from transmitting data over a predetermined period.

64. A wireless communication apparatus according to claim 60, wherein said timing control means recognizes the state in which it does not receive a signal from other station over a predetermined period calculated by a predetermined procedure before the local station transmits a packet and sets said predetermined period to be short during a predetermined time period in which it can transmit a packet with a priority.

65. A wireless communication apparatus according to claim 64, wherein said timing control means recognizes the state in which it does not receive a signal from other station over a predetermined period calculated by a predetermined procedure before the local station transmits a packet and sets said predetermined period to be long only during said predetermined time period immediately after it received a beacon from other station.

66. A wireless communication apparatus according to claim 64, wherein each of said communication stations transmits a transmission request signal and recognizes reception of a response to said transmission request signal before said communication means transmits a signal.

67. A wireless communication apparatus according to claim 66, wherein each of said communication stations does not carry out virtual carrier sense when it received the transmission request signal correctly and carries out virtual carrier sense when it received the response to said transmission request signal correctly.

68. A wireless communication apparatus according to claim 64, wherein it is determined by said communication station whether or not a media is clear over a time period corresponding to a stipulated maximum signal length before transmission when it attempts to transmit a beacon signal immediately after it is changed from a sleep state to an active state.

69. A wireless communication apparatus according to claim 64, wherein said communication station adds a preamble of a unique word to the beginning of a packet transmitted from said communication means and it also adds a mid-amble of a similar unique word to every constant payload length.

70. A wireless communication apparatus according to claim 60, wherein said timing control means, which received a stream traffic transmission request, extracts a plurality of intervals in which a beacon is not transmitted and it transmits a beacon or a signal similar to the beacon in said plurality of extracted intervals.

71. A wireless communication apparatus according to claim 70, wherein said communication station transmits said signal similar to said beacon continuously or intermittently.

72. A wireless communication apparatus according to claim 70, wherein each of said communication stations recognizes the state in which it does not receive a signal from other station over a predetermined period calculated by a predetermined procedure before the local station transmits a packet and sets said predetermined period to be short during a predetermined time period in which it can transmit a packet with a priority.

80. A wireless communication method according to claim 43, wherein each of said communication stations continues to receive a beacon from other station over a predetermined time period before starting transmission of a new beacon, it holds reception time information of a received beacon transmitted from other station as first information and it shifts information described in said received beacon indicating whether or not the local station is aware of a time at which a beacon signal is transmitted based upon said information and it holds the shifted information as second information.

81. A wireless communication method according to claim 80, wherein said communication station extracts a reception time of a beacon, which the local station or the local station and other station can receive, from said second information, it determines an interval in which a beacon reception time space becomes a maximum beacon space as a target interval and it sets a beacon transmission time of the local station to a central time of said target interval.

82. A wireless communication method according to claim 81, wherein each of said communication stations attempts to receive a signal transmitted from other station during a predetermined time period and it holds a time zone with a small frequency at which a beacon and other signal are received as third information.

83. A wireless communication method according to claim 82, wherein said communication station extracts each beacon space information, it determines an interval corresponding to a time zone with a small frequency at which a signal obtained from said third information as a target interval and sets a beacon transmission time of the local station to a central time of said target interval.

73. A wireless communication method in an ad hoc network operating under a decentralized distributed communication environment constructed when respective communication station transmit beacons with information concerning a network written therein with each other at a predetermined time space comprising the steps of:

a beacon signal generating step for generating a beacon signal in which information concerning a local station is written;

a beacon signal analyzing step for analyzing a beacon signal received from a neighboring station by a communication mechanism; and

a timing control step for controlling beacon transmission timing at which said communication mechanism transmits a beacon, said timing control step does not include using an access point, said information concerning a network including indications of beacons received from other communication stations that are part of said network, wherein

a beacon transmitted from a local station includes neighboring beacon information pertaining to a reception time at said local station of a beacon transmitted from the neighboring communication station.

74. A wireless communication method according to claim 73, wherein said information concerning the network is information indicating whether or not the local station is aware of a time at which a beacon signal is transmitted.

75. A wireless communication method according to claim 73, wherein each of said communication stations joined said network transmits a beacon signal at a predetermined time space.

76. A wireless communication method according to claim 75, wherein each of said communication stations performs reception continuously over a time period longer than its own beacon transmission interval at least once at a predetermined time.

77. A wireless communication method according to claim 74, wherein said communication station, which became aware of a time at which other station plans to transmit a beacon with reference to a clock value memorized in the local station, transmits information for prohibiting a neighboring station from transmitting data over a predetermined period.

78. A wireless communication method according to claim 74, wherein said information indicating whether or not the local station is aware of a time at which a beacon signal is transmitted is information indicated by a relative time between said time and a time at which the local station transmits a beacon signal.

79. A wireless communication method according to claim 74, wherein each of said communication station determines a beacon transmission time of the local station based on information obtained from a beacon signal which the local station can receive from other station.

84. A wireless communication method according to claim 79, wherein said communication station which received a beacon transmission time alteration request message from other station determines a new beacon transmission time.

85. A wireless communication method according to claim 73, wherein said information concerning the network is information indicating whether or not the local station is aware of a time at which a received beacon signal is transmitted.

86. A wireless communication method according to claim 85, wherein said information indicative of whether or not the local station is aware of a time at which a received beacon signal is transmitted is information indicated by a relative time between said time and a transmission time of a beacon signal from the local station.

87. A wireless communication method according to claim 85, wherein said specific time zone in which said beacon signal is transmitted is set to a transmission prohibit interval.

88. A wireless communication method according to claim 73, wherein said transmission time of a beacon signal is delayed from a predetermined target beacon transmission time by a random time and information indicative of a delayed amount is described in said beacon.

89. A wireless communication method according to claim 88, wherein said communication station, which became aware of a time at which other station plans to transmit a beacon with reference to a clock value memorized in the local station, transmits information for prohibiting a neighboring station from transmitting data over a predetermined period.

90. A wireless communication method according to claim 88, wherein when each of said communication systems receives a beacon from other communication station, it calculates a target beacon transmission time of said beacon transmission station from a beacon reception time in consideration of a time indicative of said delay amount.

91. A wireless communication method according to claim 90, wherein said communication station adjusts a clock of the local station in accordance with a timing of other station when a neighboring station target beacon transmission time predicted from the clock value memorized in the local station and a target beacon transmission time of a beacon transmission station which results from subtracting a time at which a beacon was received in actual practice and an intentionally delayed beacon transmission time described in a beacon are different from each other.

92. A wireless communication method according to claim 91, wherein said communication station adjusts a clock of the local station in accordance with a timing of other station when the target beacon transmission time of the beacon transmission station is delayed from the target beacon transmission time predicted by the local station.

93. A wireless communication method according to claim 88, wherein each of said communication stations describes a delay amount of a beacon transmission time in said beacon if said beacon transmission time is delayed due to an external primary factor when it transmits a beacon.

94. A wireless communication method according to claim 88, wherein said random time with which the beacon transmission time is delayed from the target beacon transmission time is given in the form of a pseudorandom sequence and the state of said pseudorandom sequence is transmitted as information indicative of a delay amount described in said beacon.

95. A wireless communication method according to claim 94, wherein each of said communication stations holds the state of said pseudorandom sequence described in said beacon and it calculates the next beacon transmission time of said beacon transmission station by updating a pseudorandom sequence value of every predetermined period.

96. A wireless communication method according to claim 73, wherein said communication station sets a predetermined time period in which a beacon transmission station can transmit a packet with a priority after said beacon transmission station has transmitted said beacon signal.

97. A wireless communication method according to claim 96, wherein said communication station sets a time period in which each communication station performs transmission based upon predetermined contention control after said predetermined time period in which said beacon transmission station can transmit a packet with a priority that has expired.

98. A wireless communication method according to claim 97, wherein said communication station which communicates with said beacon transmission station can transmit a packet with a priority at said predetermined time period in which said beacon transmission station can transmit a packet with a priority.

99. A wireless communication method according to claim 96, wherein said communication station, which became aware of approach of a time at which other station plans to transmit a beacon with reference to a clock value memorized in the local station, transmits information for prohibiting a neighboring station from transmitting data over a predetermined period.

100. A wireless communication method according to claim 96, wherein each of said communication stations recognizes the state in which it does not receive a signal from other station over a predetermined period calculated by a predetermined procedure before the local station transmits a packet and it sets said predetermined period to be short during a predetermined time period in which it can transmit a packet with a priority.

101. A wireless communication method according to claim 100, wherein each of said communication stations recognizes the state in which it does not receive a signal from other station over a predetermined period calculated by a predetermined procedure before the local station transmits a packet and it sets said predetermined period to be long only during said predetermined time period immediately after it received a beacon from other station.

102. A wireless communication method according to claim 100, wherein each of said communication stations transmits a transmission request signal and recognizes reception of a response to said transmission request signal before the local station transmits a beacon signal.

103. A wireless communication method according to claim 102, wherein each of said communication stations does not carry out virtual carrier sense when it received the transmission request signal correctly and it carries out virtual carrier sense when it received the response to said transmission request signal correctly.

104. A wireless communication method according to claim 100, wherein it is determined by said communication station whether or not a media is clear over a time period corresponding to a stipulated maximum signal length before transmission when it attempts to transmit a beacon signal immediately after it is changed from a sleep state to an active state.

105. A wireless communication method according to claim 100, wherein said communication station adds a preamble of a unique word to the beginning of a packet and it also adds a mid-amble of a similar unique word to every constant payload length.

106. A wireless communication method according to claim 96, wherein said communication station, which received a stream traffic transmission request, extracts a plurality of intervals in which a beacon is not transmitted and it transmits a beacon or a signal similar to the beacon in said plurality of extracted intervals.

107. A wireless communication method according to claim 106, wherein said communication station transmits said signal similar to said beacon continuously or intermittently.

108. A wireless communication method according to claim 106, wherein each of said communication stations recognizes the state in which it does not receive a signal from other station over a predetermined period calculated by a predetermined procedure before the local station transmits a packet and sets said predetermined period to be short during a predetermined time period in which it can transmit a packet with a priority.

109. A computer readable medium encoded with a computer program written in a computer readable format such that processing for being operated under a decentralized distributed communication environment in an ad hoc network constructed when respective communication stations transmit beacons with information concerning a network written thereon transmit with each other at a predetermined time space is executed on a computer system comprising the steps of:

a beacon signal generating step for generating a beacon signal in which information concerning a local station is written;

a beacon signal analyzing step for analyzing a beacon signal received from a neighboring station by a communication mechanism; and

a timing control step for controlling beacon transmission timing by said communication mechanism, said timing control step does not include using an access point, said information concerning a network including indications of beacons received from other communication stations that are part of said network, wherein

a beacon transmitted from a local station includes neighboring beacon information pertaining to a reception time at said local station of a beacon transmitted from the neighboring communication station.