Wireless local area network system

• US 5,339,316 A
• Filed: 04/02/1993
• Issued: 08/16/1994
• Est. Priority Date: 11/13/1992
• Status: Expired due to Term

• Current Assignee: NCR Corporation
• Original Assignee: NCR Corporation
• Inventors: Diepstraten, Wilhelmus J. M.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): TON, DANG T
• Application Number:
  US08/042,190
• Time in Patent Office: 501 Days
• Field of Search: 370/85.13, 370/85.1, 370/85.2, 370/85.3, 370/108, 370/60, 370/94.1, 379/61, 340/825.5, 340/825.51
• US Class Current: 370/401
• CPC Class Codes: H04L 1/1607 Details of the supervisory signal
• CPC Class Codes: H04L 1/18 Automatic repetition systems, e.g. Van Duuren systems
• CPC Class Codes: H04L 2001/0094 Bus
• CPC Class Codes: H04L 2001/125 Arrangements for preventing errors in the return channel
• CPC Class Codes: H04W 40/02 Communication route or path selection, e.g. power-based or shortest path routing
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A local area network system includes a wired backbone LAN (12) and at least one wireless LAN (14) cooperating with the backbone LAN (12) via an access point (22), which has a bridging function. When a source station (30) in the wireless LAN (14) transmits a packet to another station in the wireless LAN (14), the destination station should respond with an ACK signal. If no ACK signal is received by the source station, the packet is retransmitted. The access point (22) also receives the transmitted packet and if the access point (22) does not detect an ACK signal on the wireless channel'"'"', the access point (22) itself generates an ACK signal and retransmits the packet on the wireless LAN (14) or forwards the packet to the wired LAN (12) according to the packet destination address.

Claims

1. A method of operating a local area network system (10), including a wired local area network (12) connected via bridging means (22) to a wireless local area network (14) having a plurality of wireless stations (30) communicating over a wireless channel;

the method comprising the steps of;

transmitting from a source wireless station (30) included in said wireless local area network (14) an information packet;

receiving said information packet at said wireless stations (30) in said wireless local area network (14) and at said bridging means (22);

sensing, at said bridging means (22) whether a first acknowledgment signal (90) transmitted from a destination wireless station (30) included in said wireless local area network (14) is present on said wireless channel during a predetermined time interval (T3) following receipt of said information packet;

transmitting from said bridging means (22) a second acknowledgment signal (92) on said wireless channel if said information packet is validly received at said bridging means (22) and said first acknowledgment signal is not present during said predetermined time interval (T3); and

retransmitting said information packet from said bridging means (22) over said wireless communication channel if no first acknowledge signal is detected during said predetermined time interval (T3) and if said information packet is destined for one of said wireless stations (30).

2. The method according to claim 1, further comprising the steps of:

determining at said source (30) if a valid acknowledgment signal (90,

     92) is received; and

retransmitting said information packet if said valid acknowledgement signal 90,

     92) is not received at said source station (30).

3. The method according to claim 2, wherein:

said step of sensing includes the step of determining whether a valid first acknowledge signal (90) is received from said wireless channel during said predetermined time interval (T3).

4. The method according to claim 1, further comprising the steps of:

maintaining in said bridging means (22) a table (45) of addresses of wireless stations (30) included in said wireless local network (14); and

accessing said table (45) to determine whether said information packet is destined for one of said wireless stations (30).

5. The method according to claim 1, further comprising the step of:

forwarding said information packet from said bridging means to said wired local area network (12) if no first acknowledge signal is detected during said predetermined time interval (T3) and if said information packet is not destined for one of said wireless stations (30).

6. The method according to claims 5, further comprising the steps of:

maintaining in said bridging means (22) a table (45) of addresses of wireless stations (30) included in said wireless local network (14); and

accessing said table (45) to determine whether said information packet is destined for one of said wireless stations (30).

7. A method according to claim 1, further comprising the step of:

establishing at said wireless stations (30) an interframe spacing interval (IFS) during which said wireless stations (30) are inhibited from transmitting additional information packets following receipt of said information packet.

8. In a local area network system, including a wired local area network (12) connected via bridging means (22) to a wireless local area network (14) having a plurality of wireless stations (30) communicating over a wireless channel, the improvement comprising:

said wireless stations (30) including transmission means (32) adapted to transmit information packets over said wireless channel;

said bridging means (22) including wireless transceiver means (26,62) adapted to receive information packets transmitted over said wireless channel and to sense whether a first acknowledge signal (90) transmitted from a destination wireless station (30) included in said wireless local area network (14) is detected during a predetermined time interval (T3) following receipt of an information packet, said wireless transceiver means (26,62) being adapted to transmit a second acknowledgment signal (92) on said wireless channel of said information packet if an information packet is validly received at said bridging means (22) and if said first acknowledge signal has not been detected during said predetermined time interval (T3); and

said bridging means (22) includes further transceiver means (40), whereby if no first acknowledge signal is detected in said predetermined time interval (T3), said information packet is retransmitted by said wireless transceiver means (26,62) over said wireless channel.

9. A local area network system according to claim 8, wherein:

said bridging means (22) includes table means (45)adapted to store the addresses of stations (30) contained in said wireless local area network (14).

10. A local area network system in accordance with claim 8, wherein:

said bridging means (22) includes further transceiver means (40) coupled to said wired local area network (12), whereby if no first acknowledge signal detected in said predetermined time interval (T3), said information packet is forwarded by said further transceiver means (40) to said wired local area network (12) in accordance with destination information included in said information packet.

11. A local area network system according to claim 10, wherein:

said bridging means (22) includes table means (45)adapted to store the addresses of stations (30) contained in said wireless local area network (14).