Access protocol for a common channel wireless network

• US 5,461,627 A
• Filed: 12/24/1991
• Issued: 10/24/1995
• Est. Priority Date: 12/24/1991
• Status: Expired due to Fees

• Current Assignee: Proxim Wireless Corporation
• Original Assignee: Chandos A. Rypinski
• Inventors: Rypinski, Chandos A.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Patel, Ajit
• Application Number:
  US07/813,956
• Time in Patent Office: 1,400 Days
• Field of Search: 370/95.1, 370/85.1, 370/85.8, 370/85.2, 370/85.3, 370/85.4, 370/85.7, 370/94.2, 370/95.3, 370/94.1, 370/93, 370/100.1, 370/110.1, 379/59, 379/63, 379/56, 379/60, 455/33.1, 455/33.2, 455/53.1, 455/54.1, 455/54.2, 455/56.1, 340/825.08, 375/1
• US Class Current: 370/346
• CPC Class Codes: H04L 12/12 Arrangements for remote connection or disconnection of substations or of equipment thereof
• CPC Class Codes: H04L 12/403 with centralised control, e.g. polling
• CPC Class Codes: H04W 52/0235 where the received signal is a power saving command
• CPC Class Codes: H04W 74/06 using polling
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

An access protocol and method for a common channel wireless network addresses the functions needed in large scale wireless local or premises area networks where the user stations are or may include battery-powered portable computers and telephones either fixed or moving. The function provided is setup and rapid transfer of data packets or of virtual circuits by segmental packet transmission. Microwave radio frequencies are assumed to be the primary transmission mode, however optical propagation is also a usable medium.

Claims

1. An access method and protocol for a common channel wireless local area network, said access method comprising the steps of:

providing an access method utilizing a physical medium for the transmission of messages wherein all messages are accomplished by coding and content of a digital bit stream;

providing a fixed network infrastructure including a plurality of access points comprising antennae and radio, said access points including alternately used transmit and receive functions, and further including a hub controller connected to and sequentially controlling the transmit function in said access points by multiple electrical conductors bearing a baseband replica of the messages received and transmitted by the access points;

providing either or both fast-packet data and connection-type services from said access points to a plurality of stations to be served by wireless access;

transmitting sequential, asynchronously initiated messages that are not delayed from said access points which include either complete message sequences to said stations or invitation-to-transmit messages to enable initiation of transmission of messages from said stations when said infrastructure is available for message transfer;

receiving a request-to-use message from one or more requesting station in the plurality of said stations to any of said access points, said request-to-use message containing necessary information on the message transfer required by the requesting station;

transmitting a grant-to-use message conditioned upon resource availability from a preferred receiving access point from among the plurality of said access points to said requesting station; and

receiving a limited length digital information packet transmitted from said requesting station to said preferred receiving access point immediately following receipt of said grant-to-use message.

2. The access method and protocol of claim 1 wherein said hub controller is further connected to a means for access to other networks.

3. The access method and protocol of claim 1 wherein said sequential, asynchronously initiated messages transmitted from said access points are demand-interleaved.

4. The access method and protocol of claim 1 wherein said limited length digital information packet transmitted from said requesting station to said preferred receiving access point includes a header associating the current transmission with said previously transmitted request-to-use message, and further includes a trailer.

5. The access method and protocol of claim 1 further including the step of:

transmitting an acknowledge message from said preferred receiving access point to said requesting station after receipt of said limited length digital information packet.

6. The access method and protocol of claim 5 further including the step of:

enabling a message originated by a first station to be addressed to a second station which is near enough to receive the message directly, where said hub controller delays transmission of said acknowledge message, and where said second station promptly sends an acknowledge message indicating successful direct receipt of the message and which inhibits said hub controller and the associated access point from acknowledging or repeating said directly received message.

7. The access method and protocol of claim 6 wherein said hub controller delays transmission of said acknowledge message only when said first and second stations are associated with the same or nearby access points.

8. The access method and protocol of claim 1 wherein the physical medium for the transmission of messages is on one radio channel.

9. The access method and protocol of claim 1 wherein the physical medium for the transmission of messages utilizes separate radio channels operated in tandem for up and down links used as a common channel.

10. The access method and protocol of claim 1 wherein the physical medium for the transmission of messages is provided by optical radiation.

11. The access method and protocol of claim 1 further including the step of:

enabling nearby stations to communicate with each other when said infrastructure is not present, where a first station, after monitoring the physical medium, determines that no infrastructure is active, and the access point and hub controller protocols are simulated by said first station including the transmission of invitation-to-transmit and grant-to-use messages by said first station.

12. The access method and protocol of claim 1 further including the step of:

enabling nearby stations to communicate with each other when said infrastructure is not used or not present, where all said stations that are active have monitored the physical medium and determined that no infrastructure is active, and switch to an autonomous mode, where a first station sends a request-to-use message upon need and without regard to activity on the physical medium, and where an addressed second station responds with a grant-to-use message, and where said first station then sends a complete data message, and where said second station sends an acknowledgment message upon receiving a correct data message.

13. The access method and protocol of claim 1 further including the step of:

limiting the length of messages, where messages of greater length are broken into segments for transmission, and where each segment header uses a temporary short address to identify the related source, destination and other information in the request-to-use message from said requesting station or in the header of the first segment transmitted to said stations from said access points.

14. The access method and protocol of claim 1 further including the step of:

enabling each station upon activation to listen to the physical medium for interleaved invitation-to-register messages, and immediately upon receipt a receiving station sends a registration message containing all necessary identification information, and from which said hub controller associates the particular access point from which a satisfactory signal is received with said station to determine routing for future messages addressed to said station.

15. The access method and protocol of claim 14 further including the step of:

enabling said hub controller to conduct a background addressed poll of all registered stations, and where the response of said stations to the poll is used by said hub controller to confirm or alter said access point identification with which each said station is associated.

16. The access method and protocol of claim 15 wherein the absence of response is used to initiate a search for a registered station from other access points or to de-register a station.

17. The access method and protocol of claim 1 further including the step of:

enabling a message from a first station to be delivered to a second station which is not near enough to receive the message directly, but which is served by an access point, where said hub controller, after receiving a correct copy of the message from said first station through an access point, sends an acknowledge message to said first station, and said hub controller then retransmits said message on the access point which is assigned to said second station, and said second station, upon receipt of a correct message, sends an acknowledge message back to said access point.

18. The access method and protocol of claim 1 further including the step of:

enabling repetition of a data message from said infrastructure to a station where said hub controller initially receives no acknowledge message, where said hub controller repeats the transmission of the data message stopping after an acknowledge message is received or a predetermined number of transmissions have been made.

19. The access method and protocol of claim 18 wherein such repeated transmissions are made from alternative access points also determined to have a transmission path to said station.

20. The access method and protocol of claim 1 further including the step of:

enabling repetition of a data message from a station to said infrastructure when such message is initiated following receipt of a grant-to-use message and where said station hears no acknowledge message or hears a not-acknowledge-repeat message, where said station repeats the transmission of the data message stopping after an acknowledge message is received or a predetermined maximum number of transmissions have been made.

21. The access method and protocol of claim 1 wherein said messages include the following meanings and function for those originating at the infrastructure:

a) PACKET or SEGMENT DATA FRAMES;

b) INVITATION-TO-REQUEST;

c) ACK (knowledge); and

d) GRANT (permission-to-use);

and for those originating at the station;

e) REQUEST (request-to-transmit-data-message);

f) ACK (knowledge); and

g) PACKET or SEGMENT DATA FRAMES.

22. The access method and protocol of claim 1 wherein said messages also include the following from the infrastructure:

a) INVITATION-TO-REGISTER;

b) POLL;

c) NACK-repeat (not-acknowledge);

and the following from the station;

d) REGISTER;

e) DE-REGISTER; and

f) NACK-repeat.

23. The access method and protocol of claim 1 further including the step of:

sequentially using the common channel at each of the available access points to transmit data messages to stations and then to receive an acknowledge message indicating the successful reception of the data message, and to transmit an invitation-to-request message, to receive a request message, to transmit a grant message, and then to receive data and to transmit an acknowledge message indicating successful reception of that data.

24. The access method and protocol of claim 1 further including the step of:

enabling an infrastructure access point to respond to a station requesting permission-to-use with one of the set of following messages;

an immediate permission-to-use;

an immediate acknowledge indicating the permission-to-use will be deferred;

a not-acknowledge message after which the station repeats the request; and

no message at all within a predefined time interval causing the station to return to its initial state.