Method and apparatus for prioritizing traffic in half-duplex networks

A method in a network station of mediating collisions on network media, comprising:

• sensing a collision on the media;
• determining a priority of data to be transmitted by the network station;
• determining a slot time interval in accordance with (1) an integer randomly selected from a range of integers calculated from an exponential number of access attempts by the network station, and (2) a priority coefficient having a value corresponding to the determined priority;
• and
• attempting access of the media in response to the detected collision and after the slot time interval, wherein the determining step further comprises:
• setting the priority coefficient equal to one if the number of access attempts by the network stations is one;
• and
• setting the priority coefficient to a value less than one and greater than zero if the number of access attempts by the network station is greater than one and the determined priority is a high priority.

A method in a network station of mediating collisions on network media, comprising:

• sensing a collision on the media;
• determining a collision delay interval comprising:
• (1) randomly selecting a first integer from a range of integers calculated from an exponential number of access attempts by a network station,
• (2) first determining a number of collisions encountered by the network station,
• (3) multiplying a predetermined slot time with the first integer to obtain an integer multiple slot time interval;
• (4) if the number of collisions equals one, using the integer multiple slot time interval as the collision delay interval;
• (5) second determining if data for transmission has a priority status;
• (6) if the number of collisions is greater than one and the data has said priority status, multiplying the integer multiple slot time interval with a fractional coefficient to obtain the collision delay interval;
• and
• attempting access of the media following the collision delay interval after the detected collision.

A network interface for connection with network media, comprising:

• a buffer storing data having an identified priority for transmission on the media;
• a collision sensor sensing a collision on the media;
• a delay time calculator selectively calculating a delay time by multiplying a selected integer multiple of slot times with a fractional coefficient in response to a number of access attempts by the network interface and the identified priority;
• and
• a media access device attempting access of the media in response to the sensed collision of the media and after said delay time.

A network interface for connection with network media, comprising:

• a buffer storing data having an identified priority for transmission on the media;
• a collision sensor sensing a collision on the media;
• a delay time calculator selectively calculating a delay time in response to a number of access attempts by the network interface and the identified priority;
• and
• a media access device attempting access of the media in response to the sensed collision of the media and after said delay time,
• wherein the delay time calculator calculates said delay time as an integer multiple of a predetermined delay if the identified priority is low, the integer multiple randomly selected from an integer range calculated from an exponential number of the access attempts,
• wherein the delay time calculator calculates said delay time as a fraction of said integer multiple of said predetermined delay if the identified priority is low and the number of access attempts is greater than one.

A method in a network station of accessing a network media, comprising:

• transmitting a data packet carrying data requiring a bounded access latency;
• sensing a collision on the media;
• determining a collision delay interval by multiplying a predetermined delay interval with (1) an integer randomly selected from a range of integers calculated from an exponential number of access attempts by the network station, and (2) a priority coefficient having a value less than one if the number of said access attempts is greater than one;
• and
• attempting access of the media in response to the detected collision and after the collision delay interval.

A method of limiting access latency during data transmission in a network station, comprising:

• sensing a collision on a network media;
• if a number of access attempts is one, determining a delay time by randomly selecting between zero and a predetermined slot time;
• if the number of access attempts is greater than one, determining said delay time by (1) randomly selecting an integer, (2) multiplying the selected integer with the predetermined slot time, and (3) multiplying the selected integer multiple of slot times with a coefficient corresponding to an access latency variability;
• and
• attempting access of the media in response to the detected collision and after the determined delay time.