High-density wireless local area network
AssigneeSiemens Aktiengesellschaft
InventorsRaymond Liao, Raghuveer Chereddy, Joerg Mueller, Stefan Keller, Kai Benjamins, Christoph Weiler
Life of this patent
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Abstract
A data communication system includes an access point and a plurality of stations each for exchanging wireless data communication messages with the access point. At least some of the messages are in a format that includes at least one message header and a plurality of data units. Each of the data units includes a respective data unit header and a respective data frame. Each data unit header identifies a respective one of the stations as a recipient to receive the respective data frame of the data unit.
Claims26
A data communication system comprising:
- an access point;
- and
- a plurality of stations each for exchanging wireless data communication messages with the access point;
- wherein at least some of said messages are in a format that includes at least one message header and a plurality of data units, each of said data units including a respective data unit header and a respective data frame, each data unit header identifying a respective one of the stations as a recipient to receive the respective data frame of the data unit, and wherein said message header identifies the same recipient that is identified by the respective data unit header of a first one of said data units;
- and wherein the access point polls the stations and the stations transmit messages to the access point only in response to being polled by the access point.
A data communication system comprising:
- an access point;
- and
- a plurality of stations associated with said access point, each for exchanging wireless data communication messages with said access point, said access point polling said stations, said stations transmitting messages to the access point only in response to being polled by said access point, at least some of said messages transmitted by said stations including a respective indication to indicate that the message which includes the indication also includes at least one data unit addressed to a second one of said stations that is different from the station which transmitted the message which includes the indication.
A method of operating an access point, said access point being a part of a wireless data communication system that also includes a plurality of field devices that exchange data communication messages with the access point, the method comprising:
- the access point maintaining a respective buffer for each of said field devices, each buffer for storing no more than one control data frame for said each one of said field devices;
- the access point receiving a new control data frame appointed for transmission to one of said field devices at a time when the respective buffer for said one of said field devices stores an old control data frame appointed for transmission to said one of said field devices;
- and
- the access point responding to receiving the new data frame by storing the new control data frame in the respective buffer for said one of said field devices in place of said old control data frame.
A data communication system comprising:
- an access point;
- and
- a plurality of stations each for exchanging wireless data communication messages with the access point;
- wherein:
- each one of the stations is operative to:
- detect a timing at which a message is received by said each one of the stations;
- compare the detected timing with a nominal timing for the received message;
- and
- report to the access point a difference between the detected timing and the nominal timing;
- and
- the access point is operative to adjust a timing of transmission for a next message appointed for transmission to said each one of the stations in response to the difference reported by said each one of the stations.
A method of operating a wireless data communication system, the system including an access point and a plurality of stations associated with said access point, and each for exchanging wireless data communication messages with the access point, the access point polling said stations, said stations transmitting messages to said access point only in response to being polled by said access point, the method comprising:
- the access point polling each of said stations during a polling cycle, said polling cycle being repeated;
- and
- during each polling cycle, authorizing a respective one of said stations to include in a poll response from said authorized station a data unit addressed to another one of said stations, said data unit for transmitting to said another one of said stations a data frame from a first pre-determined type of data frame, said authorized station being the only station authorized during said each polling cycle to include in a poll response a data unit addressed to another station including a data frame from the first pre-determined type of data frame.
A method of operating a wireless data communication system, the system including an access point and a plurality of stations associated with said access point, and each for exchanging wireless data communication messages with the access point, the access point polling said stations, said stations transmitting messages to said access point only in response to being polled by said access point, the method comprising:
- a first one of the stations detecting a message transmitted by the access point, said message addressed to a second one of the stations;
- and
- said first one of the stations determining whether to initiate a handoff process in response to said detecting said message.
A method of operating a wireless data communication system, the system including a plurality of access points and a plurality of stations associated from time to time with each of said access points, each station for exchanging wireless data communication messages with the respective access point with which said each access point is associated, the method comprising:
- one of the stations engaging in a handoff procedure from a first one of said access points to a second one of said access points;
- and
- said handoff procedure including said one of the stations transmitting to said second one of said access points a frame sequence number which corresponds to a most recent data frame received by said one of the stations from said first one of said access points.
A method of operating a wireless data communication system, the system including a plurality of access points and a plurality of stations associated from time to time with each of said access points, each station for exchanging wireless data communication messages with the respective access point with which said each access point is associated, the method comprising:
- one of the stations engaging in a handoff procedure from a first one of said access points to a second one of said access points;
- said second one of said access points sending a request message to said first one of said access points to inform said first one of said access points of said handoff procedure;
- and
- said first one of said access points responding to said request message by transmitting to said second one of said access points a frame sequence number which corresponds to a most recent data frame received by said first one of said access points from said one of said stations.
A method of operating a wireless data communication system, the system including a plurality of access points and a plurality of stations associated from time to time with each of said access points, each station for exchanging wireless data communication messages with the respective access point with which said each access point is associated, the data communication system also including a controller and a data network coupling the access points to the controller, the method comprising:
- one of the stations engaging in a handoff procedure from a first one of said access points to a second one of said access points;
- said handoff procedure including said second one of said access points sending a context transfer request to said first one of said access points;
- said first one of said access points responding to said context request by transmitting to said second one of said access points data frames appointed for transmission to said one of said stations;
- and
- said second one of said access points transmitting to said one of said stations said data frames transmitted to said second one of said access points from said first one of said access points, said transmitting from said second one of said access points to said one of said stations occurring before said second one of said access points transmits to said one of said stations data frames transmitted to said second one of said access points from said controller via said data network.
Dependencies are inferred from the claim text.