Method and apparatus for multiple access over randomized slots with collision detection in a cable telephony system

A communication system comprising:

• a cable distribution network;
• a base communications unit connected to the cable distribution network, the base communications unit generating downlink data transmissions and receiving uplink data transmissions;
• a plurality of subscriber communications units connected to the cable distribution network, the plurality of subscriber communications units sending uplink data transmissions to the base communications unit in the cable distribution system to request access to the communications system, wherein uplink data transmissions from a subscriber communications unit within the plurality of subscriber communications unit are associated with downlink transmissions from the base communications unit to the subscriber communications unit and wherein each uplink data transmission and each downlink data transmission includes a synchronization pattern;
• the base communications unit monitoring uplink data transmissions from the plurality of subscriber communications units and transmitting and associated downlink data transmission in response to each uplink data transmission, each downlink data transmission including an explicit data integrity indicator indicating whether the base communications unit is able to successfully receive the uplink data transmission;
• and
• a subscriber communications unit within the plurality of subscriber communications units resending an uplink data transmission after a random period of time in response to receiving an associated downlink data transmission from the base communications unit in which the explicit data integrity indicator in the downlink data transmission indicates an inability to successfully receive the uplink data transmission because a collision has occurred between the subscriber communications unit and another subscriber communications unit in the plurality of subscriber communications units.

A subscriber communications unit comprising:

• an interface adapted for connection to a cable distribution network in a communications system;
• and
• a processor connected to the interface in which the processor has a number of modes of operation including:
• a first mode of operation in which the processor sends a first uplink data transmission from the subscriber communications unit to a base communications unit, the first uplink data transmission being sent in a time slot in a frame within a superframe;
• a second mode of operation in which the processor receives an associated downlink data transmission associated with the first uplink data transmission, wherein the associated downlink data transmission associated with the first uplink data transmission, wherein the associated downlink data transmission is associated with the first uplink data transmission by being received in a corresponding time slot and frame in a subsequent superframe;
• a third mode of operation in which the processor determines whether a collision has occurred between the first uplink data transmission from the subscriber communications unit and another uplink data transmission from another communications unit by examining the explicit data integrity indicator in the associated downlink data transmission to the subscriber communications unit;
• and
• a fourth mode of operation in which the processor automatically retransmits the first uplink data transmission after a random period of time in response to a determination that an error has occurred.

A storage device readable by a processor in a communications unit and encoding processor executable instructions for handling data collisions, the storage device comprising:

• first instruction means for sending a first uplink data transmission from the subscriber communications unit to a base communications unit, wherein the first uplink data transmission requests access to the communications system;
• second instruction means for sending a first uplink data transmission from the base communications unit;
• third instruction means for determining whether a collision has occurred between the first uplink data transmission from the subscriber communications unit and another uplink data transmission from another communications unit by examining an explicit data integrity error indicator in the associated downlink data transmission;
• and
• fourth instruction means for automatically retransmitting the first data transmission after a random period of time in response to a determination that an explicit data integrity error has occurred, wherein the instruction means are activated when the storage device is connected to a processor.

A communications unit for use in a cable communications system comprising:

• an interface adapted for connection to a distribution network in the cable communications system, the interface providing a connection for sending and receiving data transmissions on the distribution network, wherein data transmissions are transmitted on a plurality of channels, each channel being assigned a portion of a radio frequency spectrum, in which the portion of the radio frequency spectrum is divided by time into a plurality of time slots;
• and:
• a receiver connected to the interface, wherein the receiver receives modulated data signals from the interface and converts the modulated data signals into digital data;
• a transmitter connected to the interface, wherein the transmitter converts digital data into modulated data signals for transmission onto the communications system;
• a processing unit connected to the transmitter and the receiver;
• a subscriber loop interface adapted to be connected to user equipment;
• and
• a pulse code modulated coder/decoder unit connected to the transmitter, the processing unit, and the subscriber loop interface, wherein digital data containing user data is converted into an analog form for use by a user and wherein analog data from a user is converted into a digital form,
• wherein the processor sends a first uplink burst to a cable control unit, wherein the first uplink burst is made within a time slot within a frame located within a superframe and the first data transmission includes a synchronization pattern;
• receives an associated downlink burst from the cable control unit, wherein the associated downlink burst is within a corresponding time slot and frame in a subsequent superframe;
• determines whether a collision has occurred between the first uplink burst from the processor and another uplink burst from another communications unit by examining an explicit data integrity indicator in the associated downlink burst, wherein the explicit data integrity indicator indicates a collision when the cable control unit is unable to recognize the synchronization pattern;
• and retransmits the first uplink burst after a random period of time in response to a determination that an collision has occurred.

An apparatus for use in a cable communications system comprising:

• an interface adapted for connection to a distribution network in the cable communications system, the interface providing a connection for sending and receiving data transmissions on the distribution network, wherein data transmissions are transmitted on a plurality of channels, each channel being assigned a portion of a radio frequency spectrum, in which the portion of the radio frequency spectrum is divided by time into a plurality of time slots;
• and a processing unit including:
• first processing means for sending a first uplink data transmission to a base communications unit, wherein the first data transmission is made within a time slot in a frame located within a superframe and the first uplink data transmission includes a synchronization pattern;
• second processing means for receiving an associated downlink data transmission from the base communications unit, wherein the associated downlink transmission is within a corresponding time slot and frame in a subsequent superframe;
• third processing means for determining whether a collision has occurred between the first uplink data transmission from the processing unit and another uplink data transmission from another communications unit by examining an explicit data integrity indicator in the associated downlink transmission, wherein the explicit data integrity indicator indicates a collision when the base communications unit is unable to successfully receive the first uplink data transmission;
• and
• fourth processing means for retransmitting the first uplink data transmission by the processing unit after a random period of time in response to a determination that a collision has occurred.

A communica tions unit for use in a cable communications system comprising:

• an interface adapted for connection to a distribution network in the cable communications system, the interface providing a connection for sending and receiving data transmissions on the distribution network, wherein data transmissions are transmitted on a plurality of channels, each channel being assigned a portion of a radio frequency spectrum, in which the portion of the radio frequency spectrum is divided by time into a plurality of time slots;
• and
• a processing unit having a plurality of modes of operating including:
• a first mode of operation in which the processor sends a first uplink data transmission to a base communications unit, wherein the first uplink data transmission is made within a time slot within a frame located within a superframe and the first uplink data transmission includes a synchronization pattern;
• a second mode of operation in which the processor receives an associated downlink data transmission from the base communications unit, wherein the associated downlink data transmission is within a corresponding time slot and frame in a subsequent superframe;
• a third mode of operation in which the processor determines whether a collision has occurred between the first uplink data transmission of the communications unit and another uplink data transmission from another communications unit by examining an explicit data integrity indicator in the associated downlink transmission, wherein the explicit data integrity indicator indicates a collision when the base communications unit is unable to recognize the synchronization pattern;
• and
• a fourth mode of operation in which a processor retransmits the first data transmission after a random period of time in response to a determination that a collision has occurred.