Medium access protocol for wireless local area network

• US 5,422,887 A
• Filed: 06/09/1994
• Issued: 06/06/1995
• Est. Priority Date: 11/27/1991
• Status: Expired due to Term

• Current Assignee: MOSAID Technologies Inc. (f/k/a Conversant Intellectual Property Management)
• Original Assignee: NCR Corporation (NCR Voyix Corporation)
• Inventors: van Bokhorst, Hendrik, Diepstraten, Wilhelmus J. M.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): TON, DANG T
• Application Number:
  US08/257,233
• Time in Patent Office: 362 Days
• Field of Search: 370/85.1, 370/85.2, 370/86.7, 370/94.1, 370/95.1, 370/95.2, 370/100.1, 370/60, 370/85.3, 370/105.1, 370/105, 370/105.2, 370/105.4, 370/105.5, 375/107, 375/109, 375/114, 375/116
• US Class Current: 370/448
• CPC Class Codes: H04W 4/06 Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
• CPC Class Codes: H04W 74/0816 with collision avoidance
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A station which broadcasts a frame of information over a wireless local area network, waits a predetermined time calculated to allow other stations to gain access to the network, and thereafter broadcasts another frame of information. A method is provided which improves access fairness while reducing the collision probability, thereby increasing data throughput in the network.

Claims

1. A wireless local area network, comprising:

a server station; and

a client station which communicates with said server station,

wherein said server station includes (1) means for broadcasting a first frame of information, (2) means for deferring, during a predetermined time period, broadcasting of a second frame of information, said predetermined time period (a) beginning at a point in time immediately after completion of broadcast of the first frame, and (b) being calculated to allow said client station to gain access to the network, and (3) means for broadcasting the second frame, and

wherein said client station includes means for deferring broadcasting of a third frame of information by said client station (a) during broadcasting of the first frame by said server station, and (b) during a first random time period which begins at the point in time immediately after completion of broadcast of the first frame.

2. The wireless local area network of claim 1 wherein said predetermined time period is longer than said first random time period.

3. The wireless local area network of claim 2 wherein said first random time period includes a fixed time period and a random number of clock cycles.

4. The wireless local area network of claim 3 wherein said server station includes means for deferring broadcasts by said server station (a) while said client station is broadcasting said third frame, and (b) during a second random time period beginning immediately after the completion of broadcast of said third data frame.

5. The wireless local area network of claim 4 wherein the minimum value for said second random time period is less than the minimum value for said first random time period and the maximum value for said second random time period is less than the maximum value for said first random time period.

6. The wireless local area network of claim 5 wherein said first random time period further includes a second fixed time period and wherein the second random time period includes said first fixed time period and a random number of clock cycles.

7. A wireless local area network, comprising:

a server station which broadcasts data frames;

a first client station which broadcasts data frames; and

a second client station which broadcasts data frames,

wherein said server station includes (1) means for broadcasting a first data frame, (2) means for deferring, during a predetermined time period, broadcasting of a second data frame, said predetermined time period (a) beginning at a point in time immediately after completion of broadcast of the first data frame, and (b) being calculated to allow either said first client station or said second client station to gain access to the network, and (3) means for broadcasting the second data frame,

wherein said first client station includes means for deferring broadcasts of data frames by said first client station (a) during broadcasting of the first data frame by said server station, and (b) during a first random time period which begins at the point in time immediately after completion of broadcast of the first data frame; and

wherein said second client station includes means for deferring broadcasts of data frames by said second client station (a) during broadcasting of the first data frame by said server station, and (b) during a second random time period which begins at the point in time immediately after completion of broadcast of the first data frame.

8. The network of claim 7 wherein:

said server station further includes means for deferring broadcasts of data frames by said server station during a third random time period which begins at a point in time immediately after data frame broadcasts by either said first client station or said second client station; and

the third random time period of said server is statistically of shorter duration than the first random time period of said first client station or the second random time period of said second client station.

9. A method of improving data throughput performance in a wireless network having a first station and a second station, comprising:

transmitting a first data frame from the first station;

delaying transmission of a second data frame from said second station during a first random time period which begins at a point in time immediately after completion of transmission of the first data frame without collision; and

delaying transmission of a third data frame from the first station during a second time period, said second time period (a) being greater than said first random time period, and (b) beginning at the point in time immediately after completion of transmission of the first data frame without collision.

10. The method of claim 9 wherein said first station is a server.

11. The method of claim 9, wherein said first random time period includes a predetermined time period and a random backoff time period.

12. A method of improving data throughput performance-in a wireless network having a server workstation and a plurality of Client workstations comprising:

transmitting a first data frame from one of said plurality of client workstations;

delaying any attempt to transmit a second data frame from another workstation of said plurality of client workstations for at least n clock cycles after completion of transmission of the first data frame; and

delaying any attempt to transmit a third data frame from the server for at least m clock cycles after completion of transmission of the first date frame;

wherein n and m are randomly selected and the maximum value of n is greater than the maximum value of m.

13. The method of claim 12 wherein the minimum value of n is greater than the minimum value of m.

14. The method of claim 13 wherein the minimum value of n is greater than the maximum value of m.

15. The method of claim 13 further comprising:

transmitting the third data frame from said server;

delaying each further attempt to transmit data frames from any of the plurality of workstations during a third random time period which begins immediately after completion of transmission of the third data frame without collision; and

delaying each further attempt to transmit data frames from said server during a fourth time period, said fourth time period (a) being greater than said third random time period, and (b) beginning immediately after completion of transmission of the third data frame without collision.