초록 ▼

The present invention relates to a collision detection technique for an optical Star LAN using CSMA/CD. The present technique is implemented by preferably adding two or more fixed Hamming weight sequences, e.g., a fixed even or odd number of 1\s in each unique cyclic error correcting code word, to t

The present invention relates to a collision detection technique for an optical Star LAN using CSMA/CD. The present technique is implemented by preferably adding two or more fixed Hamming weight sequences, e.g., a fixed even or odd number of 1\s in each unique cyclic error correcting code word, to the preamble section of each packet of information to be transmitted. These collision detection sequences have a length which is beyond the vulnerable time period of the CSMA/CD protocol (maximum round-trip propagation delay for each packet) by at least one code word length in order to prevent any misdetection, or false detection, of a collision. Each receiver in the listening period, looks for a code pattern with a fixed Hamming weight. When code patterns collide, the Hamming weight of the resulting code word in the collision period will exceed the nominal sequence weight (will include more 1\s than the fixed Hamming weight) and a sequence weight violation is detected. Such detection is used to stop the transceivers from transmitting over the LAN and restart the network in order to avoid further collisions and network chaos.

대표청구항 ▼

A collision detection arrangement for use in a receiver of a Carrier Sense Multiple Access Collision Detection (CSMA/CD) communication network transceiver, the arrangement comprising: an input terminal for receiving a signal from the network including a packet of information which was originally tra

A collision detection arrangement for use in a receiver of a Carrier Sense Multiple Access Collision Detection (CSMA/CD) communication network transceiver, the arrangement comprising: an input terminal for receiving a signal from the network including a packet of information which was originally transmitted comprising a preamble section including a collision detection sequence of length N bit intervals and a predetermined Hamming weight, where each transceiver of the network is assigned a separate collision detection sequence; means responsive to a collision detection sequence received at the input terminal for determining the Hamming weight of the collision detection sequence and for generating an output signal representative of such weight; and means responsive to the output signal from the determining and generating means for comparing the Hamming weight of the received collision detection sequence with a predetermined threshold Hamming weight and for generating an output signal indicative of a collision of packets of information when the Hamming weight determination exceeds the threshold Hamming weight.