WIRELESS COMMUNICATION SYSTEM, COMMUNICATION CONTROL METHOD AND COMMUNICATION NODE

• US 20100278087A1
• Filed: 08/17/2007
• Published: 11/04/2010
• Est. Priority Date: 08/21/2006
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Miyamoto, Kazuhiko, Yokobori, Michiru, Kawakami, Tetsuya, Suzuki, Yoshihiro
• Granted Patent: US 8,503,343 B2
• Time in Patent Office: Days
• US Class Current: 370/311
• 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 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 74/04 Scheduled access hybrid access H04W74/02
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A technique is disclosed, by which it is possible to achieve the reduction of power consumption of each wireless node and to perform efficient access control in wireless communication system. According to this technique, a given period with a beacon transmitted from a gateway (GW) 100 at the foremost position is divided to an active period where each wireless node (P2P tag) transmits and receives a frame and a sleep period where transmitting and receiving of the frames are stopped. Further, the active period is divided to a plurality of timeslots each with a fixed length, and the period is partitioned to sub-periods where each type of a GW, a fixed node (P2P-S tag), and a mobile node (P2P-M tag) can transmit frames respectively. Each of the P2P tags selects a timeslot at random from the period for each type, and after waiting for a waiting period at random at the selected timeslot, it transmits a frame including information to identify the selected timeslot or the waiting period in addition to its own ID.

Claims

1. A wireless communication system comprising a plurality of wireless nodes, where an active period and a sleep period are repeated at a given period, transmitting and receiving operations being performed in said active period and transmitting and receiving operations being stopped in said sleep period,

wherein it is so arranged that synchronization control of said active period is carried out when a frame to indicate transmission timing information in said active period is transmitted and received.

2. The wireless communication system according to claim 1, wherein it is so arranged that said active period comprises a plurality of timeslots each with a fixed length, and a slot number at the time of frame transmission is used in said transmission timing information.

3. The wireless communication system according to claim 1, wherein it is so arranged that synchronization is readjusted by preferentially using said transmission timing information indicated by a specific frame received in said active period.

4. The wireless communication system according to claim 2, wherein it is so arranged that synchronization is readjusted by preferentially using said transmission timing information included in a specific timeslot received in said active period.

5. The wireless communication system according to claim 1, comprising a basis wireless node for transmitting a basis timing of said communication system, wherein it is so arranged that a frame outputted from said basis wireless node is used as a frame to indicate said transmission timing information in said active period.

6. The wireless communication system according to claim 2, comprising a basis wireless node for transmitting a basis timing of said communication system, wherein it is so arranged that said basis wireless node transmits a frame to indicate transmission timing information in said active period to said specific timeslot.

7. The wireless communication system according to claim 6, wherein it is so arranged that said basis wireless node transmits a frame to indicate transmission timing information in said active period in a first timeslot, said first timeslot constituting said active period.

8. The wireless communication system according to claim 1, wherein it is so arranged that each of said wireless nodes readjusts synchronization based on said transmission timing information indicated by a first received frame in said active period.

9. The wireless communication system according to claim 1, wherein:

said active period comprises a plurality of timeslots each with a fixed length;

a wireless node synchronized with said active period comprises a frame transmitting means for transmitting, after selecting said timeslot at random at the time of data transmission, a frame added with a slot number of said selected timeslot as synchronization information; and

a wireless node comprises a synchronizing means for performing, after receiving said frame added with said synchronization information synchronizing processing on said active period based on said synchronization information in said frame.

10. The wireless communication system according to claim 9, wherein it is so arranged that said synchronization information further includes transmission timing information within said timeslot to transmit said frame.

11. The wireless communication system according to claim 9, wherein it is so arranged that said frame transmitting means selects said timeslot at random to transmit said frame, confirms a using condition of transmission route by CSMA/CA, and transmits said frame only in case it is judged that said timeslot to transmit said frame is not in use.

12. The wireless communication system according to claim 11, wherein it is so arranged that said frame transmitting means selects a timing to start transmission of said frame at random from a plurality of timings at said timeslot selected for transmission of said frame.

13. The wireless communication system according to claim 9, wherein it is so arranged that said synchronizing means performs monitoring of a frame on a transmission route during one beacon period at maximum when own wireless node is in non-synchronized state to said active period, said beacon period being said given period including said active period and said sleep period, and performs synchronization processing based on synchronization information included in said received frame.

14. The wireless communication system according to claim 9, wherein it is so arranged that said synchronizing means performs synchronization readjustment processing based on said synchronization information included in a first received frame in said active period in case own wireless node is already synchronized to said active period.

15. The wireless communication system according to claim 9, wherein it is so arranged that said wireless node belongs to either type of a fixed node fixedly set or a mobile node to move, said fixed node performs monitoring of a frame on a transmission route during one beacon period at maximum when own wireless node is in non-synchronized state to said active period, said beacon period being said given period including said active period and said sleep period, and does not perform synchronization processing in case said frame from the basis wireless node to transmit basis timing of said communication system or from said fixed node cannot be received.

16. The wireless communication system according to claim 9, wherein it is so arranged that said wireless node belongs to either type of a fixed node fixedly set or a mobile node to move, said timeslot of said active period being divided to a timeslot for the basis wireless node to transmit basis timing of said communication system, to a timeslot for said fixed node, and to a timeslot for said mobile node set up thereafter, and said mobile node does not perform monitoring of a frame on a transmission route in said timeslot for the mobile node in case said frame has been received at the timeslot for said basis wireless node or for said fixed node.

17. The wireless communication system according to claim 9, wherein it is so arranged that, when said frame has been received at a timeslot for basis wireless node to transmit basis timing of said communication system or for said fixed node in said active period, said wireless node compares said frame with said basis wireless node or with said fixed node received in previous active period, and said wireless node performs frame transmission processing by said frame transmitting means only in case the frame has been received from a different wireless node.

18. The wireless communication system according to claim 9, wherein it is so arranged that said wireless node does not carry out synchronization readjustment processing in said active period in case said frame is not received at any of the timeslots in said active period, and said wireless node continues communication in synchronized state in the previous active period, and in case said frame has not been received at any of the timeslots continuously for the prescribed number of times or more, it is regarded as out of synchronization, and said wireless node performs processing to be performed in non-synchronized state.

19. The wireless communication system according to claim 9, wherein it is so arranged that said wireless node reserves a specific transmission timing in the next active period when transmitting a packet at a specific transmission timing within an arbitrary active period.

20. The wireless communication system according to claim 9, wherein it is so arranged that said wireless node reserves a timeslot in communication in the next active period when transmitting a packet at an arbitrary timeslot in an arbitrary active period.

21. The wireless communication system according to claim 19, wherein it is so arranged that a specific timing in the next active period present at the same position as a specific transmission timing where said packet can be transmitted at a specific transmission timing within said arbitrary active period is reserved as said specific transmission timing in communication in said next active period.

22. The wireless communication system according to claim 20, wherein it is so arranged that a timeslot in the next active period present at the same position as a timeslot where said packet can be transmitted at an arbitrary timeslot in said arbitrary active period is reserved as said timeslot in communication of said next active period.

23. The wireless communication system according to claim 20, wherein it is so arranged that said wireless node having reserved said timeslot performs processing for transmitting said packet from a foremost position of timeslots in communication in said next active period.

24. The wireless communication system according to claim 19, wherein it is so arranged that, when receiving a packet including a request of reservation of said specific transmission timing from other wireless node, said wireless node avoids said specific transmission timing to request reservation by said other node and selects transmission timing for data transmission.

25. The wireless communication system according to claim 20, wherein it is so arranged that, when receiving a packet including a request of reservation of said timeslot from other wireless node, said wireless node avoids said timeslot requested reservation by said other wireless node and selects the timeslot for data transmission.

26. The wireless communication system according to claim 19, wherein it is so arranged that, in case a packet including a request of reservation of said specific transmission timing is not received from other wireless node, said wireless node searches a transmission timing for data transmission so that said data transmission may not collide with data transmission by said other wireless node.

27. The wireless communication system according to claim 20, wherein it is so arranged that, in case a packet including a request of reservation of said timeslot is not received from other wireless node, said wireless node searches a timeslot where data transmission can be performed so that said data transmission may not collide with data transmission by said other wireless node.

28. The wireless communication system according to claim 19, wherein it is so arranged that, when said wireless node transmits a packet at a specific transmission timing in an arbitrary active period, said wireless node reserves a chance of communication in said next active period by specifying a specific transmission timing in the next active period.

29. The wireless communication system according to claim 20, wherein it is so arranged that said wireless node reserves a timeslot to be used in said next active period by specifying said timeslot in the next active period in a packet to transmit a timeslot in an arbitrary active period.

30. A wireless communication system comprising a plurality of wireless nodes, where an active period and a sleep period are repeated at a given period, said active period consisting of a plurality of timeslots each with a fixed length where said plurality of wireless nodes can transmit and receive data, a transmitting/receiving unit of said wireless node being in inactive state in said inactive period,

wherein it is so arranged that, when transmitting a packet at an arbitrary timeslot in an arbitrary active period, said wireless node reserves a timeslot in the communication in the next active period.

31. The wireless communication system according to claim 30, wherein it is so arranged that a timeslot in the next active period present at the same position as a timeslot where said packet can be transmitted at an arbitrary timeslot in said arbitrary active period is reserved as said timeslot in the communication in said next active period.

32. The wireless communication system according to claim 30, wherein it is so arranged that said wireless node, after having reserved said timeslot, performs processing for transmitting said packet from a foremost position of timeslots in communication in said next active period.

33. The wireless communication system according to claim 30, wherein it is so arranged that, in case a packet including a request of reservation of said timeslot is received from other wireless node, said wireless node avoids said timeslot requested reservation by said other wireless node and selects the timeslot for data transmission.

34. The wireless communication system according to claim 33, wherein it is so arranged that, in case a packet including a request of reservation of said timeslot is not received from other wireless node, said wireless node searches a timeslot where data transmission can be performed so that said data transmission may not collide with data transmission by said other wireless node.

35. A communication control method in a wireless communication system comprising a plurality of wireless nodes and a basis node where an active period and a sleep period are repeated at a given period, said active period consisting of a plurality of timeslots each with a fixed length where said plurality of wireless nodes and said basis node can transmit and receive frames, a transmitting/receiving unit of said wireless node being in inactive state in said inactive period, wherein said basis node transmits frames to a basis timeslot repeated at a given period, comprising:

a frame transmitting step of transmitting by said wireless node, after selecting said timeslot at random at the time of data transmission, a frame added with a slot number of said selected timeslot as synchronization information; and

a synchronization step of performing synchronization processing to said active period based on said synchronization information in said frame by the wireless node receiving said frame added with said synchronization information.

36. The communication control method according to claim 35, wherein it is so arranged that said synchronization information further includes transmission timing information in said timeslot to transmit said frame.

37. The communication control method according to claim 35, wherein said frame transmitting step further comprises the steps of selecting said timeslot to transmit said frame at random, confirming a condition of use of a transmission route by CSMA/CA, and transmitting said frame only in case it is judged that said timeslot where said frame is transmitted is not in use.

38. The communication control method according to claim 37, wherein said frame transmitting step further comprises a step of selecting a timing to start transmission of said frame at random from a plurality of timings at said timeslot selected for transmitting said frame.

39. The communication control method according to claim 35, wherein said synchronization step further comprises the steps of performing monitoring of a frame on a transmission route during one beacon period at maximum when own wireless node is in non-synchronized state to said active period, said beacon period being said given period including said active period and said sleep period, and performing synchronization processing based on synchronization information included in said received frame.

40. The communication control method according to claim 35, wherein said synchronization step further comprises the steps of performing synchronization readjustment processing based on said synchronization information included in a first received frame in said active period in case own wireless node is already synchronized with said active period.

41. The communication control method according to claim 35, further comprising a synchronization control step in which said wireless node belongs to either type of a fixed node fixedly set or a mobile node to move, said fixed node performs monitoring of a frame on a transmission route during one beacon period at maximum when own wireless node is in non-synchronized state to said active period, said beacon period being said given period including said active period and said sleep period, and controls not so as to perform synchronization processing in case said frame from the basis wireless node to transmit basis timing of said communication system or from said fixed node cannot be received.

42. The communication control method according to claim 35, further comprising a monitoring control step in which said wireless node belongs to either type of a fixed node fixedly set or a mobile node to move, said timeslot of said active period is divided to a timeslot for the basis wireless node to transmit basis timing of said communication system, a timeslot for said fixed node, and to a timeslot for said mobile node set up thereafter, said mobile node controls not so as to perform monitoring of a frame on a transmission route in said timeslot for the mobile node in case said frame has been received at the timeslot for said basis wireless node or for said fixed node.

43. The communication control method according to claim 35, further comprising a frame transmission processing control step in which, when said frame has been received at a timeslot of said active period for said basis wireless node or for said fixed node, said mobile node controls so as to compare said frame with said basis wireless node or with said fixed node received in previous active period, and said mobile node controls not so as to perform frame transmission processing by said frame transmitting means only in case the frame has been received from a different wireless node.

44. The communication control method according to claim 35, further comprising a non-synchronization control step in which, said wireless node controls so as not to carry out synchronization readjustment processing in said active period in case said frame is not received at any of the timeslots in said active period, and said wireless node controls so as to continue communication in synchronized state in the previous active period, and in case said frame has not been received at any of the timeslots continuously for the prescribed number of times or more, it is regarded as out of synchronization, and said wireless node controls so as to perform processing to be performed in non-synchronized state.

45. The communication control method according to claim 44, wherein, when transmitting a packet at an arbitrary timeslot in an arbitrary active period, said wireless node reserves a timeslot in the communication in the next active period.

46. The communication control method according to claim 45, wherein a timeslot in the next active period present at the same position as a timeslot where said packet can be transmitted at an arbitrary timeslot in said arbitrary active period is reserved as said timeslot in the communication of said next active period.

47. The communication control method according to claim 45, wherein said wireless node having reserved said timeslot performs processing for transmitting said packet from a foremost position of timeslots in a communication in said next active period.

48. The communication control method according to claim 45, wherein, when receiving a packet including a request of reservation of said timeslot from other wireless node, said wireless node avoids said timeslot requested the reservation by said other wireless node and selects the timeslot for data transmission.

49. The communication control method according to claim 48, wherein, in case a packet including a request of reservation of said timeslot is not received from other wireless node, said wireless node searches a timeslot where data transmission can be performed so that said data transmission may not collide with data transmission by said other wireless node.

50. A communication method in a wireless communication system comprising a plurality of wireless nodes where an active period and a sleep period are repeated at a given period, said active period consisting of a plurality of timeslots each with a fixed length where said plurality of wireless nodes can transmit and receive data, a transmitting/receiving unit of said wireless node being in inactive state,

wherein, when transmitting a packet at an arbitrary timeslot in an arbitrary active period, said wireless node reserves a timeslot in the communication in the next active period.

51. The communication method according to claim 50, wherein a timeslot in the next active period present at the same position as a timeslot where said packet can be transmitted at an arbitrary timeslot in said arbitrary active period is reserved as said timeslot in communication in said next active period.

52. The communication method according to claim 50, wherein said wireless node, after having reserved said timeslot, performs processing for transmitting said packet from a foremost position of timeslots in communication in said next active period.

53. The communication method according to claim 50, wherein, when receiving a packet including a request of reservation of said timeslot from other wireless node, said wireless node avoids said timeslot requested the reservation by said other wireless node and selects the timeslot for data transmission.

54. The communication method according to claim 53, wherein, in case a packet including a request of reservation of said timeslot is not received from other wireless node, said wireless node searches a timeslot where data transmission can be performed so that said data transmission may not collide with data transmission by said other wireless node.

55. A communication control method in a wireless communication system comprising a plurality of wireless nodes where an active period and a sleep period are repeated at a given period, transmitting and receiving operations being performed in said active period and transmitting and receiving operations being stopped in said sleep period,

wherein synchronization of said active period is controlled by transmitting and receiving frames to indicate transmission timing information in said active period.

56. The communication method according to claim 55, wherein said wireless node reserves a specific transmission timing in a next active period when transmitting a packet at a specific transmission timing within an arbitrary active period.

57. A communication node for performing communication by synchronizing with an active period, said active period having transmission timing of frames to be transmitted by a given basis node at a given period and comprising a plurality of timeslots each with a fixed length where frames can be transmitted and received, comprising:

a frame transmitting means for transmitting frames added with given synchronization information after selecting said timeslot at random at the time of data transmission, when own communication node is synchronized to said active period; and

a synchronizing means for performing synchronization processing to said active period based on said synchronization information in said frame when said frame added with said synchronization information has been received.

58. The communication node according to claim 57, wherein it is so arranged that a slot number of said selected timeslot is used as said synchronization information.

59. The communication node according to claim 58, wherein it is so arranged that said synchronization information further includes transmission timing information within said timeslot to transmit said frame.

60. The communication node according to claim 57, wherein it is so arranged that said frame transmitting means selects said timeslot at random to transmit said frame, confirms a using condition of transmission route by CSMA/CA, and transmits said frame only in case it is judged that said timeslot to transmit said frame is not in use.

61. The communication node according to claim 60, wherein it is so arranged that said frame transmitting means selects a timing to start transmission of said frame at random from a plurality of timings at said timeslot selected for transmission of said frame.

62. The communication node according to claim 57, wherein it is so arranged that said synchronizing means performs monitoring of a frame on a transmission route during one beacon period at maximum when own wireless node is in non-synchronized state to said active period, and said synchronizing means, said beacon period being said given period including said active period and a sleep period where a transmitting/receiving unit of said wireless node are in inactive state, and performs synchronization processing based on synchronization information included in said received frame.

63. The communication node according to claim 57, wherein it is so arranged that said synchronizing means performs synchronization readjustment processing based on said synchronization information included in a first received frame in said active period in case own wireless node is already synchronized to said active period.

64. The communication node according to claim 57, wherein it is so arranged that said wireless node belonging to either type of a fixed node fixedly set or a mobile node to move, said fixed node performs monitoring of a frame on a transmission route during the one beacon period at maximum in case it is in non-synchronized state to said active period, said beacon period being said given period including said active period and a sleep period where a transmitting/receiving unit of said wireless node are in inactive state, said communication node does not perform synchronization processing in case said frame from the basis wireless node or from said fixed node cannot be received.

65. The communication node according to claim 57, wherein it is so arranged that, said wireless node belonging to either type of a fixed node fixedly set or a mobile node to move, said timeslot of said active period being divided to a timeslot for the basis wireless node, to a timeslot for said fixed node, and to a timeslot for said mobile node as set up thereafter, said mobile node does not perform monitoring of a frame on a transmission route in said timeslot for the mobile node in case said frame has been received at the timeslot for said basis wireless node or for said fixed node.

66. The communication node according to claim 57, wherein it is so arranged that, when said frame has been received at a timeslot for said basis wireless node or for said fixed node in said active period, said communication node compares said frame with said basis wireless node or with said fixed node received in previous active period, and said communication node performs frame transmission processing by said frame transmitting means only in case the frame has been received from a different wireless node.

67. The communication node according to claim 57, wherein it is so arranged that said communication node does not carry out synchronization readjustment processing in said active period in case said frame is not received at any of the timeslots in said active period, and said communication node continues communication in synchronized state in the previous active period, and in case said frame has not been received at any of the timeslots continuously for the prescribed number of times or more, it is regarded as out of synchronization, and said communication node performs the processing in non-synchronized state.

68. The communication node according to claim 57, wherein it is so arranged that said communication node reserves a timeslot in communication in the next active period when transmitting a packet at an arbitrary timeslot in an arbitrary active period.

69. The communication node according to claim 68, wherein it is so arranged that a timeslot in the next active period present at the same position as a timeslot where said packet can be transmitted at an arbitrary timeslot in said arbitrary active period is reserved as said timeslot in communication of said next active period.

70. The communication node according to claim 68, wherein it is so arranged that, when said communication node reserves said timeslot, said communication node performs processing for transmitting said packet from a foremost position of timeslots in communication in said next active period.

71. The communication node according to claim 68, wherein it is so arranged that, when receiving a packet including a request of reservation of said timeslot from other wireless node, said communication node avoids said timeslot requested reservation by said other wireless node and selects the timeslot for data transmission.

72. The communication node according to claim 71, wherein it is so arranged that, in case a packet including a request of reservation of said timeslot is not received from other wireless node, said communication node searches a timeslot where said data transmission can be performed so that said data transmission may not collide with data transmission by said other wireless node.

73. A communication node for performing communication in synchronization with an active period, said active period comprising a plurality of timeslots each with a fixed length where data can be transmitted and received;

wherein it is so arranged that, when transmitting a packet at an arbitrary timeslot in an arbitrary active period, a timeslot in communication in a next period is reserved.

74. The communication node according to claim 73, wherein it is so arranged that a timeslot in the next active period present at the same position as a timeslot where said packet can be transmitted at an arbitrary timeslot in said arbitrary active period is reserved as said timeslot in communication of said next active period.

75. The communication node according to claim 73, wherein it is so arranged that, in case of having reserved said timeslot, said communication node performs processing for transmitting said packet from a foremost position of timeslots in communication in said next active period.

76. The communication node according to claim 73, wherein it is so arranged that, when receiving a packet including a request of reservation of said timeslot from other wireless node, said communication node avoids said timeslot requested reservation by said other wireless node and selects the timeslot for data transmission.

77. The communication node according to claim 76, wherein it is so arranged that, in case a packet including a request of reservation of said timeslot is not received from other wireless node, said communication node searches a timeslot where said data transmission can be performed so that said data transmission may not collide with data transmission by said other wireless node.

79. The communication node according to claim 75, wherein, when transmitting a packet at a specific transmission timing in an arbitrary active period, said communication node reserves a specific transmission timing in the next active period.

78. A communication node for performing communication in a wireless communication system where an active period and a sleep period are repeated at a given period, transmitting and receiving operations being performed in said active period and transmitting and receiving operations being stopped in said sleep period,

wherein it is so arranged that said communication node performs synchronization control of said active period by transmitting and receiving a frame indicating transmission timing information in said active period to and from other communication node.