COMMUNICATION TERMINAL AND METHOD FOR WIRELESS SENSOR NETWORK

• US 20090180452A1
• Filed: 01/12/2009
• Published: 07/16/2009
• Est. Priority Date: 01/11/2008
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Nguyen, Vu Thuy Dan, Choi, Hyo Hyun, Kim, Jeong Geun, Kim, Sun Gi, KIM, Eui Jik
• Granted Patent: US 8,194,695 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• 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 communication terminal and method is provided for improving channel utilization efficiency in a wireless sensor network using contention-based channel access mechanism is disclosed. The communication method according to the present invention comprises initializing, when a packet transmission is required, a contention window to a size; resetting, when a channel is assessed to be busy, the size of the contention window in a hybrid expansion mode; and attempting, when the channel is assessed to be idle, the packet transmission through the channel.

Claims

1. A communication method for a terminal in a wireless sensor network using a contention-based channel access mechanism, comprising:

initializing a contention window to a known size, when a packet transmission is required;

resetting the size of the contention window in a hybrid expansion mode, when a channel is assessed to be busy; and

attempting the packet transmission through the channel, when the channel is assessed to be idle.

2. The communication method of claim 1, wherein resetting the size of the contention window comprises:

increasing the size of the contention window linearly, when a parameter indicates a linear expansion, and

increasing the size of the contention window exponentially, when the parameter indicate an exponential expansion,.

3. The communication method of claim 2, further comprising:

counting a number of resets of the contention window.

4. The communication method of claim 3, wherein increasing the size of the contention window linearly comprises calculating a new size of the contention window as:

CW_i=CW_i-1+c, mod (I, n)≠

0(i≧

1),

wherein i is the number of resets,

CW_i is the size of the contention window,

CW_i-1 is a previous size of the contention window,

c is a linear expansion constant, and

n is a number of expansion resets in which the size of contention window is expanded.

5. The communication method of claim 3, wherein increasing the size of the contention window exponentially comprises calculating a new size of the contention window as:

CW_i=eCW_i-1, mod(I, n)=0(i≧

1),

wherein e is an exponential expansion constant.

6. The communication method of claim 1, wherein initializing the contention window comprises calculating the size of the contention window as:

CW_i=CW_min, i=0,

wherein the CW_min is a minimum size of the contention window.

7. The communication method of claim 6, wherein the number of expansion resets is 3, the linear expansion constant is 2, and the exponential constant is 2, and the minimum size of the contention window is 8.

8. The communication method of claim 3, further comprising:

assessing whether the channel is to be idle in the contention window, and

transmitting, when the channel is assed to be idle in the contention window, the packet through the channel.

9. A communication terminal of a wireless sensor network using a contention-based channel access mechanism, comprising:

a memory unit which stores a packet carrying data collected by the terminal;

a control unit which;

initializes a contention window to a size, when a packet transmission is required,

resets, the size of the contention window in a hybrid expansion mode when a channel is assessed to be busy, and

attempts the packet transmission through the channel, when the channel is assessed to be idle, and

a radio frequency unit which collects the data and transmits the packet when the channel is assessed to be idle.

10. The communication terminal of claim 9, wherein the control unit increases the size of the contention window linearly, when a parameter indicates a linear expansion, and increases the size of the contention window exponentially, when the parameter indicate an exponential expansion.

11. The communication terminal of claim 10, wherein the control unit counts a number of resets of the contention window.

12. The communication terminal of claim 9, wherein the control unit increase the size of the contention window as:

CW_i=CW_i-1+c, mod (I,n)≠

0(i≧

1),

wherein i is the number of resets,

CW_i is the size of the contention window,

CW_i-1 is a previous size of the contention window,

c is a linear expansion constant, and

n is a number of expansion resets in which the size of contention window is expanded.

13. The communication terminal of claim 9, wherein the control unit increases the size of the contention window exponentially as:

CW_i=eCW_i-1, mod(I,n)=0(i≧

1),

wherein e is an exponential expansion constant.

14. The communication terminal of claim 9, wherein the control unit initializes the size of the contention window as:

CW_i=CW_min, i=0,

wherein the CW_min is a minimum size of the contention window.

15. The communication terminal of claim 14, wherein the number of expansion resets is 3, the linear expansion constant is 2, and the exponential constant is 2, and the minimum size of the contention window is 8.

16. A contention-based channel access mechanism device, comprising:

a processor in communication with a memory the memory including code, which when accessed by the code causes the processor to;

initialize a contention window to a known size, when a packet transmission is required;

reset the size of the contention window in a hybrid expansion mode, when a channel is assessed to be busy; and

attempt the packet transmission through the channel, when the channel is assessed to be idle.

17. The device of claim 16, wherein resetting the size of the contention window comprises:

increasing the size of the contention window linearly, when a parameter indicates a linear expansion, and

increasing the size of the contention window exponentially, when the parameter indicate an exponential expansion.

18. The device of claim 17, wherein the processing executing code for:

counting a number of resets of the contention window.

19. The device of claim 17, wherein increasing the size of the contention window linearly comprises calculating a new size of the contention window as:

CW_i=CW_i-1+c, mod (I,n)≠

0(i≧

1),

wherein i is the number of resets,

CW_i is the size of the contention window,

CW_i-1 is a previous size of the contention window,

c is a linear expansion constant, and

n is a number of expansion resets in which the size of contention window is expanded.

20. The device of claim 17, wherein increasing the size of the contention window exponentially comprises calculating a new size of the contention window as:

CW_i=eCW_i-1, mod(I,n)=0(i>

1),

wherein e is an exponential expansion constant.

21. The device of claim 16, wherein initializing the contention window comprises calculating the size of the contention window using an equation,

CW_i=CW_min, i=0,

wherein the CW_min is a minimum size of the contention window.

22. The device of claim 21, wherein the number of expansion resets is 3, the linear expansion constant is 2, and the exponential constant is 2, and the minimum size of the contention window is 8.

23. The device of claim 16, further comprising:

assessing whether the channel is to be idle in the contention window, and

transmitting, when the channel is assed to be idle in the contention window, the packet through the channel.