Method and apparatus for detecting collisions on a network

• US 5,963,539 A
• Filed: 09/08/1997
• Issued: 10/05/1999
• Est. Priority Date: 09/08/1997
• Status: Expired due to Fees

• Current Assignee: Tut Systems, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Tut Systems, Inc. (Motorola Solutions, Inc.)
• Inventors: Webber, Harold H. Jr., Jeffress, Jeremiah
• Primary Examiner(s): HSU, ALPUS
• Application Number:
  US08/925,043
• Time in Patent Office: 757 Days
• Field of Search: 370/212, 370/213, 370/445, 370/447, 370/448, 370/461, 370/462, 370/509, 370/514, 341/52, 341/53, 341/178, 341/182, 341/183, 340/825.06, 340/825.07, 340/825.16, 340/825.17, 340/825.5, 340/825.52, 340/825.57, 375/238, 375/239, 375/362, 375/364
• US Class Current: 370/213
• CPC Class Codes: H04L 12/2803 Home automation networks
• CPC Class Codes: H04L 12/2838 Distribution of signals within a home automation network, e.g. involving splitting/multiplexing signals to/from different paths adaptations of television systems for transmission by electric cable for domestic distribution H04N7/106; hybrid transport H04L12/6418; home network arrangements specially adapted for distribution of digital video signals H04N7/24
• CPC Class Codes: H04L 12/40013 Details regarding a bus controller
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
• CPC Class Codes: H04L 2012/2845 Telephone line

Abstract

A method and apparatus for detecting a collision between signal transmissions on a carrier medium, such as UTP wiring, are described. The method commences with the transmission of an access identifier from a transmitter of a network device. The transmitted access identifier has a predetermined duration and includes a pulse at a temporal location within the transmitted access identifier specific thereto. An access identifier is also received at a receiver of the network device. The received access identifier also has a predetermined duration, and includes a pulse at a temporal location therein. A determination is then made as to whether the temporal location of the pulse within the received access identifier corresponds to the temporal location of the pulse within the transmitted access identifier. If not, a collision is detected on the network.

Claims

1. A method of detecting a collision between signal transmissions on a carrier medium in a network, the method including:

transmitting a first access identifier from a transmitter of a network device, the first access identifier having a predetermined duration and including a pulse at a temporal location within the first access identifier specific thereto;

receiving a second access identifier at a receiver of the network device, the second access identifier having a predetermined duration and including a pulse at a temporal location within the second access identifier;

determining whether the temporal location of the pulse within the second access identifier corresponds to the temporal location of the pulse within the first access identifier; and

if not, then detecting a collision on the network.

2. The method of claim 1 wherein the first access identifier includes a plurality of pulses, each having a temporal location within the first access identifier specific to the first access identifier, the method including determining whether the respective temporal locations of the pulses within the first access identifier correspond to temporal locations of pulses included within the second access identifier and, if not, then detecting a collision in the network.

3. The method of claim 1 including transmitting a jamming signal upon the detection of a collision in the network, the jamming signal comprising a series of pulses spaced at regular intervals.

4. The method of claim 1 including implementing a silence gap, in which no pulses are transmitted, after transmission of the first access identifier and detecting a collision on the network if a pulse is received at the receiver during the silence gap.

5. The method of claim 1 including incorporating a buffer period between the transmission of the first access identifier and transmission of a subsequent access identifier so as to allow reflections on the carrier medium, generated by transmission of the pulse within the first access identifier, to decay to a predetermined level before transmission of the subsequent access identifier.

6. The method of claim 1 including blocking the receiver'"'"'s ability to detect a pulse greater than a specific amplitude after detection of the pulse within the second access identifier.

7. The method of claim 6 including decreasing the specific amplitude over a period equal to the buffer period.

8. Apparatus for detecting a collision between signal transmissions on a carrier medium in a network, the apparatus including:

a transmitter coupled to transmit a first access identifier over the carrier medium, the first access identifier having a predetermined duration and including a pulse at a temporal location within the first access identifier specific thereto;

a receiver coupled to receive a second access identifier transmitted over the carrier medium, the second access identifier having a predetermined duration and including a pulse at a temporal location within the second access identifier; and

a logic circuit, coupled to the receiver, that determines whether the temporal location of the pulse within the second access identifier corresponds to the temporal location of the pulse within the first access identifier and, if not, that detects a collision on the network.

9. The apparatus of claim 8 wherein the first access identifier includes a plurality of pulses, each having a temporal location within the first access identifier specific to the first access identifier, the logic circuit being configured to determine whether the respective temporal locations of the pulses within the first access identifier correspond to temporal locations of pulses included within the second access identifier and, if not, to detect a collision in the network.

10. The apparatus of claim 8 wherein the transmitter is configured to transmit a jamming signal upon detection of a collision in the network, the jamming signal comprising a series of pulses spaced at regular intervals.

11. The apparatus of claim 8 wherein the transmitter is configured to implement a silence gap, in which no pulses are transmitted, after transmission of the first access identifier and the logic circuit is configured to detect a collision on the network if a pulse is received at the receiver during the silence gap.

12. The apparatus of claim 8 wherein the transmitter is configured to include a buffer period between the transmission of the first access identifier and transmission of a subsequent access identifier so as to allow reflections on the carrier medium, generated by transmission of the pulse within the first access identifier, to decay to a predetermined level before transmission of the subsequent access identifier.

13. The apparatus of claim 8 wherein the receiver is configured not to detect a pulse greater than a specific amplitude after detection of the pulse within the second access identifier.

14. The apparatus of claim 13 including a threshold circuit coupled to the receiver and configured to decrease the specific amplitude over a period corresponding to the buffer period.

15. An adapter for providing a coupling between a network station and a carrier medium, the adapter including:

a network station interface;

a carrier medium interface;

a transmitter, coupled to the carrier medium interface, configured to transmit a station access identifier over the carrier medium, the station access identifier being associated with the network station and including a pulse having a temporal location within the station access identifier specific thereto;

a receiver, coupled to the carrier medium interface, and configured to receive a further station access identifier transmitted over the carrier medium, the further station access identifier including a pulse at a temporal location; and

a logic circuit, coupled to the receiver, configured to determine whether the temporal location of the pulse within the further station access identifier corresponds to the temporal location of the pulse within the station access identifier and, if not, to detect a collision on the network.