Wireless mesh network system and control method thereof, and wireless device

• US 9,055,521 B2
• Filed: 11/05/2009
• Issued: 06/09/2015
• Est. Priority Date: 11/10/2008
• Status: Active Grant

• Current Assignee: Futaba Corporation
• Original Assignee: Futaba Corporation
• Inventors: Iwasa, Tadashi
• Primary Examiner(s): Nooristany, Sulaiman
• Application Number:
  US12/591,022
• Publication Number:
  US 20100118750A1
• Time in Patent Office: 2,042 Days
• Field of Search: 370/328
• US Class Current: 1/1
• CPC Class Codes: H04W 40/24 Connectivity information management, e.g. connectivity discovery or connectivity update
• CPC Class Codes: H04W 74/0808 using carrier sensing, e.g. carrier sense multiple access [CSMA]

Abstract

A wireless mesh network system includes a plurality of wireless devices and is adapted to forward a message packet. Each of the wireless devices includes a transmitter, a receiver, a communications controller, and a RAM. Further, the communications controller detects a reception completion time of a message packet received, and controls such that, if the wireless device had performed forwarding the message packet received right before, a carrier sense time, which is the time from the reception completion time to the forwarding start, is set to be longer than a previously set carrier sense time, and if the corresponding wireless device had not performed forwarding the message packet received right before, the carrier sense time is set to be shorter than the previously set carrier sense time.

Claims

1. A wireless mesh network system, which includes a plurality of wireless devices and is adapted to forward a message packet,

wherein each of the wireless devices comprises:

a transmitter, a receiver, a communications controller, and a RAM, and

wherein the communications controller detects a reception completion time of a message packet received, and controls such that,

when the wireless device had performed forwarding the message packet received right before, a carrier sense time, which is the time from the reception completion time to a forwarding start time, is always set to be longer than a previously set carrier sense time, and

when the wireless device had not performed forwarding the message packet received right before and the wireless device recognizes a transmission from a wireless device other than a wireless device which had previously sent the message packet, the carrier sense time is set to be shorter than the previously set carrier sense time.

2. The wireless mesh network system of claim 1, wherein the communications controller changes the carrier sense time in a stepwise manner, and controls such that,

when the wireless device had performed forwarding the message packet received right before, a carrier sense time, which is the time from the reception completion time to the forwarding start time, is set to a maximum value, and

when the wireless device had not performed forwarding the message packet received right before, the carrier sense time is set to be shorter than the previously set carrier time by one level.

3. The wireless mesh network system of claim 1, wherein the communications controller generates a random number, and sets the carrier sense time by adding the random number.

4. A wireless device having a transmitter, a receiver, a communications controller, and a RAM which is included in a wireless mesh network system adapted to forward a message packet,

wherein the communications controller detects a reception completion time of a message packet received, and controls such that,

when the wireless device had performed forwarding the message packet received right before, a carrier sense time, which is the time from the reception completion time to a forwarding start time, is always set to be longer than a previously set carrier sense time, and

when the wireless device had not performed forwarding the message packet received right before and the wireless device recognizes a transmission from a wireless device other than a wireless device which had previously sent the message packet, the carrier sense time is set to be shorter than the previously set carrier sense time.

5. A control method of a wireless mesh network system which has a plurality of wireless devices and is adapted to forward a message packet, each of the wireless devices having a transmitter, a receiver, a communications controller, and a RAM, comprising:

by the communications controller of each wireless device,

detecting a reception completion time of a message packet received;

when the wireless device had performed forwarding the message packet received right before, always setting a carrier sense time, which is the time from the reception completion time to a forwarding start time, to be longer than a previously set carrier sense time; and

when the wireless device had not performed forwarding the message packet received right before and the wireless device recognizes a transmission from a wireless device other than a wireless device which had previously sent the message packet, setting the carrier sense time to be shorter than the previously set carrier sense time.