Abstract: A novel and useful media access control (MAC) protocol that is intended for use over noisy shared media channels. The MAC protocol provides layer 2 functionality over a network using a shared medium including a backoff mechanism for CSMA/CA channel access, link addressing that reduces the overhead of long MAC addresses, a flooding scheme having controlled exposure for broadcast transmissions, multicast transmissions using selective ACKs, implementation of traffic prioritization using an adaptive backoff scheme, a second layer repeater establishment process and multi-packet transport for short packets and fragmentation for long packet transport.

Abstract: A novel and useful acquisition and synchronization mechanism for spread spectrum communication systems whereby a synchronization sequence comprising a plurality of known symbols spaced apart by predefined time delay intervals is transmitted as the start of packet signal. At the transmitter, a synchronization sequence is transmitted at the beginning of each packet. A synchronization sequence is generated which includes a plurality of symbols with predefined time gaps between each of the symbols. Multiple synchronization sequences may be generated wherein each sequence comprises a unique set of time delays or gaps between each of the symbols. Each set of unique time delays or gaps between symbols of a sequence is stored as a synchronization sequence gap template in memory.

Abstract: A novel and useful mechanism for detecting intrusion and jamming attempts by an imposter node. A time window defined as an emergency window is reserved after the end of a packet and before an acknowledgement window. Nodes that detect the presence of an intruder transmit an emergency packet during the emergency time window to inform the receive node that the packet it received was sent from an imposter node. Attempts to jam the transmission of the emergency packet from the victim node to the receive node are detected by listening during the emergency window time period for carrier signal that indicates that an emergency packet is trying to be sent. An emergency packet request message is sent by the receive node in response which causes the victim node to resend the emergency packet.

Abstract: An apparatus for and a method of iterative equalization for communication over noisy channels suitable for use with a wide range of different types of communications systems and channels that is particularly applicable to power line based communication systems. Equalization of received symbols is achieved by iteratively removing the influence of previous symbols dispersed due to channel ISI. Equalization is performed using iterative subtraction in combination with calculations based on the inverse of the transfer matrix. The impulse response of previous symbols is subtracted out to yield the impulse response of the received symbol. The estimate of the current symbol {tilde over (B)}n is then calculated by passing the modified received symbol through a matched filer which functions to remove the effect of channel ISI from the symbol. Multiple iterations are performed to improve the accuracy of the resultant symbol decision.

Abstract: A novel and useful distributed synchronization mechanism. The synchronization loop of each station on the shared media based network considers only synchronization signals received having a time phase earlier than the time phase of its internal clock. From among the plurality of synchronization signals received by a given station having a time phase earlier than that of its internal clock, only the earliest of the received synchronization signals is considered. This allows the use of a second order synchronization tracking loop wherein both the phase and rate of the internal clock are tracked and adjusted. The station with the fastest internal clock effectively functions as an ad-hoc synchronization master for all stations in a given maximum connected group.

Abstract: A novel media access control (MAC) mechanism utilizing synchronization signaling that enables nodes from different networks having different technologies and protocols to coexistence using the same shared media. The present invention is suitable for use with a wide range of different types of network and technologies and is particularly useful in providing coexistence capabilities to powerline based data communication systems. Specific time slots are assigned for the transmission of a frame occupation signal to indicate to all nodes that the channel is occupied. A synchronization signal is randomly transmitted during a preassigned time slot within the frame to provide accurate timing for the frame occupation signal. During times that a node does not transmit the synchronization signal, it listens to the channel. A timing signal is derived from the synchronization signals received from other nodes during this quiet period wherein the node is in a listening mode.