Data communications method using backoff number control
A method for transmitting data in a centralized data communications system having an access point and a plurality of stations using a carrier sense multiplexing access (CSMA) method using a backoff number control preferably includes (a) receiving a multi-poll message containing backoff numbers to be assigned to each station by the access point; (b) setting the backoff numbers of the multi-poll message to the backoff numbers of the stations; and (c) counting down the set backoff numbers and transmitting data. Each station that desires polling registers a station ID and a polling cycle, sets a backoff number contained in a multi-poll message, counts the backoff number, and if the backoff number becomes zero, transmits data such that contention between stations is prevented.
1. A data transmission method using a backoff number control in a centralized data communications system, which includes an access point and a plurality of stations, comprising:
(a) receiving a multi-poll message containing backoff numbers to be assigned to each station by the access point;
(b) determining at each station if a station ID corresponding to that station is identified in the multi-poll message;
(c) setting the backoff numbers of the stations to the corresponding backoff numbers assigned by the multi-poll message;
(d) counting down the set backoff numbers before transmitting data from one of the plurality of stations; and
(e) resetting the backoff number to a value obtained by adding the current number of stations identified in the multi-poll message to a randomly generated backoff number in a station that is not among the identified stations.
2. The method as claimed in claim 1 , further comprising:
registering IDs and polling cycles of the stations to be polled at the access point.
3. The method as claimed in claim 1 , wherein in (a) the multi-poll message contains at least one of the number of stations to be polled, the station IDs, or backoff numbers of the stations.
4. The method as claimed in claim 3 , wherein in (c) each station to be polled checks the IDs of stations in the multi-poll message and sets a backoff number corresponding to the respective station.
5. The method as claimed in claim 1 , wherein in (d) the set backoff number is counted down and when the backoff number becomes zero, data is transmitted.
6. The method as claimed in claim 1 , further comprising:
setting the number of stations to be polled as the minimum value in the range of random values for generating backoff numbers if there is a station having no data to be transmitted among the stations to be polled.
7. The method as claimed in claim 1 , further comprising:
setting the number of stations to be polled as the minimum value in a range of random values to be generated if there is no station waiting to obtain the transmission opportunity by randomly setting the backoff number.
8. A computer readable medium having embodied thereon a computer program for the method of claim 1 .
9. A computer readable medium having embodied thereon a computer program for the method of claim 2 .
10. A computer readable medium having embodied thereon a computer program for the method of claim 3 .
11. A computer readable medium having embodied thereon a computer program for the method of claim 4 .
12. A computer readable medium having embodied thereon a computer program for the method of claim 5 .
13. A computer readable medium having embodied thereon a computer program for the method of claim 6 .
14. A computer readable medium having embodied thereon a computer program for the method of claim 7 .