SYSTEM AND METHOD FOR RANDOM ACCESS SCHEME IN A WIRELESS AD-HOC NETWORK

• US 20100008347A1
• Filed: 07/14/2008
• Published: 01/14/2010
• Est. Priority Date: 07/14/2008
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd. (Samsung Group)
• Original Assignee: Samsung Electronics Co. Ltd. (Samsung Group)
• Inventors: Ngo, Chiu, Qin, Xiangping
• Granted Patent: US 8,102,822 B2
• Time in Patent Office: Days
• US Class Current: 370/345
• CPC Class Codes: H04W 74/04 Scheduled access hybrid access H04W74/02
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02
• CPC Class Codes: H04W 74/0816 with collision avoidance
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

A system and method for random access scheme in a wireless ad-hoc network is disclosed. In one aspect, the method comprises transmitting data to a receiving node in a wireless ad-hoc network in a first time block previously reserved for transmission. The method further comprises transmitting data to the receiving node in a second time block if the reservation is periodic, the second time block starting at a time being a fixed amount of time L after the start of the first time block.

Claims

1. A method of reserving channel bandwidth for transmission in a wireless ad-hoc network, the method comprising:

at a transmitter node in a wireless ad-hoc network;

transmitting data to a receiving node in a wireless ad-hoc network in a first time block previously reserved for data transmission; and

transmitting data to the receiving node in a second time block if the reservation is periodic, the second time block starting at a time being a fixed amount of time L after the start of the first time block.

2. The method of claim 1, further comprising:

prior to the transmitting of data in the first and second time block;

scanning the wireless channel for the fixed amount of time (L) to determine whether there is free channel time;

transmitting a first request-to-send (RTS) frame to the receiving node if there is free channel time, the first RTS message indicating the first time block reserved for channel use and whether the reservation is periodic; and

receiving a first clear-to-send (CTS) frame from the receiving node confirming the reservation requested;

3. The method of claim 2, further comprising transmitting a second RTS message prior to transmitting data in the second time block.

4. The method of claim 2, further comprising receiving a second CTS message prior to transmitting data in the second time block.

5. The method of claim 3, wherein the second RTS message indicates the second time block reserved for channel use and whether the reservation is periodic.

6. The method of claim 3, further comprising transmitting a third RTS message indicating a third time block reserved for channel use and whether the reservation is periodic

7. The method of claim 2, wherein the first time block starts at a random time point.

8. The method of claim 2, wherein the duration of the first time block is less than L.

9. The method of claim 2, wherein the transmitting node communicates to the receiving node via directional transmission.

10. The method of claim 2, wherein the transmitting node communicates to the receiving node via omnidirectional transmission.

11. The method of claim 2, wherein the first RTS message is transmitted in free channel time as determined by the channel scanning.

12. The method of claim 2, wherein the first time block is selected to be in free channel time.

13. The method of claim 2, wherein the scanning of a wireless channel comprising, upon detecting a RTS or CTS message indicating a periodic reservation and a reserved time block, determining that the channel is not free during the reserved time block and another time block, the other time block starting at a time being L after the start of the reserved time block.

14. The method of claim 2, wherein the channel is not scanned between the data transmission in the first time block and the data transmission in the second time block.

15. The method of claim 2, further comprising:

at the receiver node in the wireless ad-hoc network;

receiving the first RTS message;

scanning a wireless channel at the receiving node for the fixed amount of time (L) to determine whether the channel is free for the time requested by the first RTS message; and

transmitting a first clear-to-send (CTS) frame confirming the reservation requested by the first RTS message if the channel is free for the time requested.

16. The method of claim 15, wherein the scanning of a wireless channel at the receiving node comprises, if the first RTS message requests periodic reservation, determining that the time requested is not available if the channel is not free during the first time block or the second time block.

17. The method of claim 15, further comprising transmitting a response rejecting the reservation requested by the first RTS message and proposing a different reservation time, if the channel is free for the time requested.

18. A computer-readable medium having stored a software module which, when being executed by a computer, performs the method of claim 1.

19. A device for data transmission in a wireless ad-hoe network, the device comprising:

a storage unit having stored therein a software module; and

a control unit configured to execute the software module to;

transmit data to a receiving node in a wireless ad-hoc network in a first time block previously reserved for data transmission; and

transmit data to the receiving node in a second time block if the reservation is periodic, the second time block starting at a time being a fixed amount of time L after the start of the first time block.

20. The device of claim 19, wherein the control unit is further configured to:

prior to the transmitting of data in the first and second time block;

scan the wireless channel at the transmitting node for the fixed amount of time (L) to determine whether there is free channel time;

transmit a first request-to-send (RTS) frame to the receiving node if there is free channel time, the first RTS message indicating the first time block reserved for channel use and whether the reservation is periodic; and

receive a first clear-to-send (CTS) frame from the receiving node confirming the reservation requested by the first RTS message.

21. A device for data transmission in a wireless ad-hoc network, the device comprising:

a storage unit having stored therein a software module; and

a control unit configured to perform the software module to;

transmit a first periodic clear-to-send (CTS) message to a transmitting node in a wireless ad-hoc network in a first time block previously reserved for periodic transmission; and

transmit a second periodic CTS message to the transmitting node in a second time block if the reservation is periodic, the second time block having the same duration as the first time block and starting at a time being with a fixed amount of time (L) after the start of the first time block.

22. The device of claim 21, wherein the control unit is further configured to:

prior to the transmitting of the first and second periodic CTS messages;

receive an initialization request-to-send (RTS) frame from the transmitting node, the first RTS message indicating the first time block reserved for periodic channel use;

scan a wireless channel for the fixed amount of time (L) to determine whether the channel is free for the time requested by the initialization RTS message;

transmit an initialization clear-to-send (CTS) frame to the transmitting node confirming the reservation requested by the initialization RTS message if the channel is free for the time requested;

23. The device of claim 22, wherein the channel is not scanned between the transmitting of the first periodic CTS message and the second periodic CTS message.