Applied Micro Circuits Corporation

University of California

Qualcomm Incorporated

Kenneth Yun

Kirk Alvin Miller

Kevin Warren James

George Bendak

Sushil Kumar Singh

Michael Hellmer

John David Huber

Philip Michael Clovis

Prayag Bhanubhai Patel

David Thomas Dougherty

Peter John Holzer

Eli James Aubrey Fernald

Jianfeng Shi

Viet Linh Do

John Calvin Leung

Ayoob Eusoof Dooply

Rene L Cruz

Michael Sluyski

Manish Amde

Receivers and reception methods conduct spread spectrum reception using the energy of multiple bits, preferably a substantial number of bits, in a packet for correct alignment of the spreading code at the receiver. Code acquisition, as well as packet detection and acquisition are provided by embodiments of the invention. Preferred embodiment receivers and reception methods provide packet detection at low SINR looking at energy of multiple bits of the packet, frame synchronization using short preamble, timing recovery at low SINR looking at energy of multiple bits of the packet, quick code acquisition using parallel search for all possible code phases, code acquisition at low SINR, and tracking of acquired timing and code phase. Preferred embodiment receivers and reception methods use the energy of multiple bits for making decisions.

Spread-spectrum receiver and reception method

A system and method are provided for fairly distributing grants for access to switch outputs, through crossbars, between switch input channels. Crossbars are granted access between specified switch inputs and switch outputs, and the least recently used input channels are associated with selected switch outputs. A history of the previous channel transaction is maintained for each switch output, and channels are nominated in a rotation through a priority channel list. The present invention bid grant algorithm permits information packets to be transferred across a switch in the time between a bid submission and a bid grant.

System and method for reevaluating granted arbitrated bids

System and method for granting arbitrated bids in the switching of information

A system and method are provided for tolerating data line faults in a packet communications switch fabric. The method comprises: accepting information packets including a plurality of cells, at a plurality of ingress port card ports, the plurality of information packets addressing a plurality of egress port card ports; selectively connecting port card ports to port card backplane data links; selectively connecting port card backplane data links and crossbars; sensing a connection fault in a backplane data link; in response to sensing the fault, reselecting connections between the port card ports and the port card backplane data links; in response to reselecting connections between the port card ports and the port card backplane data links, serially transferring packets through the port cards; serially transferring packets through the crossbars to the egress port cards; and, suspending use of the faulty connection.

System and method for tolerating data link faults in a packet communications switch fabric

A system and method are provided for resynchronizing backplane link management credit counters in a packet communications switch fabric. The method comprises: at an input port card ingress port, accepting information packets including cells and cell headers with destination information; modifying the destination information in the received cell headers; routing information packets between the input port card and output port cards on backplane data links through an intervening crossbar; at the input port card, maintaining a credit counter for each output port card channel; decrementing the counter in response to transmitting cells from the input port card; generating credits in response to transmitting cells from an output port card channel; sending the generated credits to increment the counter, using the modified destination information; and, using the generated credit flow to resynchronize the credit counter.

System and method for synchronizing switch fabric backplane link management credit counters

A system and method are provided for configuring interface bandwidths in a packet communications switch fabric. The method comprises: interfacing data links with a first plurality of traffic managers (TMs); differentiating port card interface ports into a first plurality of subchannels associated with the first plurality of TMs; and, communicating packets information with the TMs at a first plurality of data rates corresponding to the first plurality of subchannels. More specifically, differentiating port card interface ports into a first plurality of subchannels associated with the first plurality of TMs includes: differentiating a second plurality of ingress data links into a third plurality of ingress subchannels associated with a third plurality of ingress traffic managers (iTMs); and, differentiating a fourth plurality of egress data links into a fifth plurality of egress subchannels associated with a fifth plurality of egress TMs (eTMs).

Configurable switch fabric interface bandwidth system and method

A system and method are provided for communicating control information in a switch fabric. The method comprises: on a switch card, establishing a plurality of crossbars controlled by an arbiter; initiating a control message; and, distributing the control message on a switch card token bus connecting the crossbars and arbiter elements. Distributing the control message on a switch card token bus connecting the crossbar and arbiter elements includes daisy-chain connecting the elements with a cyclical bus. In some aspects of the method, establishing a plurality of crossbars controlled by an arbiter includes identifying each element with a unique address. Then, initiating a control message includes initiating a control message with an attached address. Distributing the control message on a switch card token bus includes the substeps of: daisy-chain passing the control message between elements; and, terminating the message at an element having an address matching the address attached to the control message.

System and method for communicating switch fabric control information

A credit-based system and method are provided for managing backplane traffic flow in a packet communications switch fabric. The method comprises: accepting information packets including cells and cell headers with destination information; modifying the destination information in the received cell headers; routing information packets between an input port card and output port cards on backplane data links through an intervening crossbar; at the input port card, maintaining a credit counter for each output port card channel; decrementing the counter in response to transmitting cells from the input port card; generating credits in response to transmitting cells from an output port card channel; and, using modified destination information, sending the generated credits to increment the counter. In some aspects, modifying the destination information in the received packet headers includes: extracting the output port card termination from the card field; and, inserting the input port card source in the card field.

Switch fabric backplane flow management using credit-based flow control

A system and method are provided for communicating TDM communications through a packet switch fabric. The method comprises: accepting native TDM frames; converting the native TDM frames to fabric-cellified TDM frames; differentiating the cells of each frame into time slots; interleaving the frame time slots; TDM scheduling the interleaved frame time slots; and, routing the interleaved frame time slots between input port cards and output port cards on backplane data links through an intervening crossbar. TDM scheduling the interleaved frame time slots includes: an input port card ingress memory subsystem (iMS) receiving a first TDM configuration schedule including interleaved frame time slots cross-referenced to backplane transmission times; and, an output port card egress MS (eMS) receiving a second TDM configuration schedule including interleaved frame time slots cross-referenced to egress channel transmission times. Then, the routing is performed in response to the TDM schedules.

System and method for communicating TDM traffic through a packet switch fabric

A system and method are provided for cut-through packet routing in a packet communications switch fabric. The method comprises: accepting information packets addressed to a plurality of output port card egress ports at an input port card ingress port; routing information packets between port cards on backplane data links through an intervening crossbar; maintaining a credit counter for each port card egress destination, at the input port card; decrementing the counter in response to transmitting cells in a packet from the input port card; and, incrementing the counter in response to transmitting cells from the packet at the output port card. In some aspects of the method, accepting information includes buffering the packets in an ingress memory subsystem (iMS). Routing information includes the iMS transmitting buffered packets on a selected backplane data link. Decrementing the counter includes the iMS communicating with the iPQ in response to transmitting a cell.

Minimum latency cut-through switch fabric

A system and method are provided for tolerating data line faults in a packet communications network. The method comprises: serially transmitting information packets from at least one traffic manager (TM); at a switch fabric, accepting information packets at a plurality of ingress ports, the information packets addressing destination port card egress ports; selectively connecting port card ingress ports to port card egress ports; serially supplying information packets from a plurality of port card egress ports; sensing a connection fault between the switch fabric and the TM; and, in response to sensing the fault, reselecting connections between the switch fabric port card ports and the TM. Some aspects comprise: an ingress memory subsystem (iMS) receiving cells on an ingress port exceeding an error threshold. Then, reselecting connections between the port card ports and the TM includes the iMS sending a message to the iTM identifying the faulty ingress connection.

System and method for tolerating data link faults in communications with a switch fabric

A system and method are provided for tolerating control link faults in a packet communications switch fabric. The method comprises: accepting information packets including a plurality of cells, at a plurality of port card ports, the plurality of information packets addressing a plurality of port card ports; selectively connecting port card ports to port card backplane data links; in response to backplane control link communications, selectively connecting port card backplane data links and crossbars; sensing a connection fault in a control link; and, in response to sensing the control link fault, reselecting connections between the port card ports and the port card backplane data links. In some aspects, selectively connecting port card backplane data links and crossbars includes: for a particular backplane data link, fixedly connecting each port card to a corresponding interface of an assigned crossbar; and, selectively enabling the connection to each crossbar.

System and method for tolerating control link faults in a packet communications switch fabric

A system and method have been provided for prioritizing queued information packets having a variable number of cells. A simultaneous deficit round robin (DRR) analysis occurs in the course of several selection cycles. Each queue has an associated increment value. The packet lengths in each queue are simultaneously compared to an accumulation total in every selection cycle. If all the packets have lengths greater than their corresponding accumulation totals, each accumulation total is incremented and the selection process is repeated. If one of the information packets has a number of cells less than, or equal to its corresponding accumulation total, it is selected. In case multiple information packets are eligible, a variety of selection criteria can be used to break a tie. For example, the eligible information packet with the highest class of service (COS) can be selected. The information packet is completed transferred before another selection process is begun.

System and method for simultaneous deficit round robin prioritization

A system and method have been provided for hierarchically arbitrating in a broadband information switching network. The method promotes the fair and efficient distribution of information packets across the switch fabric that ultimately permits the switch to maximally match information packets to switch output addresses, at faster rates and higher throughput. The method comprises: accepting variably sized information packets at a plurality of switch inputs, that address a plurality of switch outputs; at each switch input, queuing the information packets into a plurality of queues; parsing the information packets into units of one cell; simultaneously arbitrating between each switch output and a plurality of available switch inputs, where an available input is defined to have at least one queue with an information packet addressing that particular switch output; selecting a queue; locking the link between switch inputs and switch outputs; and, transferring information packets across the links in units of one cell per master decision cycle.

System and method for hierarchical switching

The cell switching architecture of the present invention uses at least one earliest deadline first (EDF) queue for each of the output ports in a cell switch so that no two output ports have a common earliest-deadline-first queue. Cells are arranged in each EDF queue according to deadline, but each EDF queue only contains cells for a single destination output port. Each input port also has an input queue with an EDF queue for each of the output ports, and each EDF queue arranges the cells for a single output port. Many equivalent cells may be represented by a single EDF queue entry, enabling large buffer capacity to be supported by small EDF queues. The architecture provides a method for switching cells between a plurality of input ports and a plurality of output ports. Cells are accepted from input ports into a plurality of corresponding input queues. Cells are sorted into groups according to the destination output port such that each group includes cells destined for a single output port. Within each input queue, at least one group is formed for every output port for which cells are available. Cells are arranged, within each group, according to deadline. By means of a central arbiter, output ports then choose cells to read in a read cycle from the earliest deadline cells in their corresponding cell groups in the input queues. An efficient method is used to select cells with the earliest deadlines.

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San Diego, CA, United States of America

Kenneth Yun