Access control system for wireless-lan terminals

• US 5,828,663 A
• Filed: 12/01/1995
• Issued: 10/27/1998
• Est. Priority Date: 12/02/1994
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Ikegami, Yoshikazu
• Primary Examiner(s): Marcelo, Melvin
• Assistant Examiner(s): LEE, CHI HO A
• Application Number:
  US08/564,685
• Time in Patent Office: 1,061 Days
• Field of Search: 370/329, 370/341, 370/347, 370/348, 370/445, 370/448, 370/462, 340/825.5
• US Class Current: 370/347
• CPC Class Codes: H04W 28/10 Flow control between communication endpoints
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A wireless-LAN terminal comprises a wired-LAN controller, a wireless modem and an access controller intervening between the wired-LAN controller and the wireless modem. In the access controller, the termination of data reception and the occurrence of a transmission request are detected by monitoring a frame-sense (FS) signal and a request-to-send (RTS) signal, respectively. An IFS period is generated by a delay timer when the data reception is terminated and a random amount of time is generated by using a backoff algorithm when the transmission request occurs during a transmission inhibition period. The data transmission is waited until the random amount of time comes to an end, and the data transmission is started when the random amount of time has elapsed and the transmission channel is available. Since a backoff period is determined randomly for each terminal, there is a remarkably reduced probability that a plurality of terminals concurrently start the media access for data transmission.

Claims

1. An access control method of a wireless terminal in a wireless network employing a carrier sense multiple access (CSMA) scheme, said method comprising the steps of:

monitoring the termination of a transmission inhibition period;

monitoring the occurrence of a transmission request;

generating a random-determined time period when said transmission request occurs during said transmission inhibition period, said random-determined time period starting from said termination of said transmission inhibition period;

waiting to start data transmission associated with said transmission request until said random-determined time period has elapsed after said termination of said transmission inhibition period;

checking whether a predetermined channel for transmission is available at the end of said random-determined time period; and

starting said data transmission associated with said transmission request when said random-determined time period has elapsed and said predetermined channel for transmission is available.

2. The access control method according to claim 1, wherein said transmission inhibition period is a total of a data reception period and a predetermined time period following said data reception period, said predetermined time period is previously determined depending on said wireless network.

3. The access control method according to claim 2, wherein said predetermined time period is determined by an interframe spacing (IFS) period for spacing between data frames, and said random-determined time period is determined by a predetermined backoff processing procedure.

4. An access control method of a wireless terminal in a wireless network employing a carrier sense multiple access (CSMA) scheme, said method comprising the steps of:

a) monitoring the termination of data reception;

b) monitoring the occurrence of a transmission request;

c) generating a time period when said data reception is terminated, said time period starting from said termination of said data reception, and said time period being predetermined depending on said wireless network;

d) generating a random amount of time when said transmission request occurs during a transmission inhibition period comprising a total of a data reception period and said time period;

e) waiting to start data transmission associated with said transmission request until said random amount of time comes to an end;

f) checking whether a predetermined channel for transmission is available at the end of said random amount of time;

g) starting said data transmission associated with said transmission request when said random amount of time has elapsed and said predetermined channel for transmission is available;

h) repeating said steps (d)-(g) while said predetermined channel for transmission is not available until the repetition number reaches a predetermined maximum value; and

i) stopping said step (g) when said predetermined channel for transmission is not available with the repetition number exceeding said predetermined maximum value.

5. The access control method according to claim 4, wherein said time period is determined by an interframe spacing (IFS) period for spacing between data frames, and said random amount of time is determined by a predetermined backoff processing procedure.

6. The access control method according to claim 4, wherein said wireless network employs a carrier sense multiple access with collision detection (CSMA/CD) scheme.

7. An access control system of a wireless terminal in a wireless network employing a carrier sense multiple access (CSMA) scheme, said system comprising:

first monitoring means for monitoring the termination of a transmission inhibition period;

second monitoring means for monitoring the occurrence of a transmission request;

generating means for generating a random-determined time period when said transmission request occurs during said transmission inhibition period, said random-determined time period starting from said termination of said transmission inhibition period; and

control means for controlling a transmission process such that data transmission associated with said transmission request waits until said random-determined time period has elapsed after said termination of said transmission inhibition period, it is checked whether a predetermined channel for transmission is available at the end of said random-determined time period, and said data transmission associated with said transmission request is started when said random-determined time period has elapsed and said predetermined channel for transmission is available.

8. The system according to claim 7, wherein said transmission inhibition period is a total of a data reception period and a predetermined time period following said data reception period, said predetermined time period is previously determined depending on said wireless network.

9. The system according to claim 8, wherein said predetermined time period is determined by an interframe spacing (IFS) period for spacing between data frames, and said random-determined time period is determined by a predetermined backoff processing procedure.

10. An access control system of a wireless terminal in a wireless network employing a carrier sense multiple access (CSMA) scheme, said system comprising:

first monitoring means for monitoring the termination of data reception;

second monitoring means for monitoring the occurrence of a transmission request;

first generating means for generating a time period when said data reception is terminated, said time period starting from said termination of said data reception, and said time period being predetermined depending on said wireless network;

second generating means for generating a random amount of time when said transmission request occurs during a transmission inhibition period including a total of a data reception period and said time period; and

control means for performing a first transmission process control such that data transmission associated with said transmission request waits until said random amount of time comes to an end, it is checked whether a predetermined channel for transmission is available at the end of said random amount of time, and said data transmission associated with said transmission request starts when said random amount of time has elapsed and said predetermined channel for transmission is available.

11. The system according to claim 10, wherein said time period is determined by an interframe spacing (IFS) period for spacing between data frames, and said random amount of time is determined by a predetermined backoff processing procedure.

12. The system according to claim 11, wherein said wireless network employs a carrier sense multiple access with collision detection (CSMA/CD) scheme.

13. The system according to claim 10, wherein said control means further performs a second transmission process control such that said first transmission process control is repeated while said predetermined channel for transmission is not available until the repetition number reaches a predetermined maximum value, and said data transmission is stopped when said predetermined channel for transmission is not available with the repetition number exceeding said predetermined maximum value.

14. A terminal in a wireless local-area network (LAN), said terminal comprising:

a wireless transmitting-receiving system having a channel monitoring function;

a wired-LAN controller incorporating a carrier sense multiple access with collision detection (CSMA/CD) scheme; and

an access controller intervening between said wireless transmitting-receiving system and said wired-LAN controller,

said access controller comprising;

first monitoring means for monitoring the termination of data reception;

second monitoring means for monitoring the occurrence of a transmission request;

first generating means for generating a time period when said data reception is terminated, said time period starting from said termination of said data reception, and said time period being predetermined depending on said wireless network;

second generating means for generating a random amount of time when said transmission request occurs during a transmission inhibition period including a total of a data reception period and said time period; and

control means for performing a first transmission process control such that data transmission associated with said transmission request waits until said random amount of time comes to an end, it checks whether a predetermined channel for transmission is available at the end of said random amount of time, and said data transmission associated with said transmission request starts when said random amount of time has elapsed and said predetermined channel for transmission is available.

15. The terminal according to claim 14, wherein said time period is determined by an interframe spacing (IFS) period for spacing between data frames, and said random amount of time is determined by a predetermined backoff processing procedure.

16. The terminal according to claim 14, wherein said control means further performs a second transmission process control such that said first transmission control is repeated while said predetermined channel for transmission is not available until the repetition number reaches a predetermined maximum value, and said data transmission is stopped when said predetermined channel for transmission is not available with the repetition number exceeding said predetermined maximum value.

17. A terminal in a wireless local-area network (LAN), said terminal comprising:

a wireless transmitting-receiving system having a channel monitoring function;

a wired-LAN controller incorporating a carrier sense multiple access with collision detection (CSMA/CD) scheme; and

an access controller intervening between said wireless transmitting-receiving system and said wired-LAN controller,

said access controller comprising;

a delay timer generating a time period when data reception is terminated, said time period starting from said termination of said data reception, and said time period being predetermined depending on said wireless LAN network;

a backoff processor generating a random amount of time when a transmission request is received from said wired-LAN controller during a transmission inhibition period including a total of a data reception period and said time period; and

a transmission process controller performing a first transmission process control such that data transmission associated with said transmission request waits until said random amount of time comes to an end, it is checked whether a predetermined channel for transmission is available at the end of said random amount of time, and said data transmission associated with said transmission request starts when said random amount of time has elapsed and said predetermined channel for transmission is available.

18. The terminal according to claim 17, wherein said time period is determined by an interframe spacing (IFS) period for spacing between data frames.

19. The terminal according to claim 17, wherein said transmission process controller further performs a second transmission process control such that said first transmission control is repeated while said predetermined channel for transmission is not available until the repetition number reaches a predetermined maximum value, and said data transmission is stopped when said predetermined channel for transmission is not available with the repetition number exceeding said predetermined maximum value.