摘要:
In one embodiment, an algorithm dynamically selects a method for reducing distortion in a multi-carrier modulated signal, such as an orthogonal frequency division multiplexing (OFDM) signal. The algorithm directs a transmitter to transmit peak-to-average power ratio (PAPR)-reduction signals over reserved tones (i.e., frequencies) if reserved tones are available. If reserved tones are not available, then the algorithm directs the transmitter to transmit PAPR-reduction symbols over free tones if free tones are available. If the free tones for this transmitter are used by adjacent transmitters, then interference-reduction techniques may be used to reduce interference with the adjacent transmitters. If reserved tones and free tones are not available, then the transmitter may use an alternative method to reduce distortion, such as successive clipping and filtering. In another embodiment, the transmitter may transmit PAPR-reduction symbols over both free and reserved tones, if available.
摘要:
In a packet-based (e.g., Ethernet) network, such as the network of central offices and base stations of a wireless telephone system, a node receives one or more incoming packet-based signals from one or more other nodes of the network and recovers a clock signal from each incoming packet-based signal. The node selects one of the recovered clock signals as the node's reference clock signal. When the node is part of a base station, the node uses the selected clock to generate and transmit one or more outgoing packet-based signals to one or more central offices. The node also uses the selected clock to generate the base station's wireless transmissions. In one implementation, the base stations and central offices are connected by Ethernet facilities.
摘要:
Methods and apparatus are provided for N+1 packet level mesh protection. An error correction encoder is provided for encoding message symbols, m0 through mN-1, to generate a codeword that includes the message symbols, m0 through mN-1, and one or more check symbols. The error correction encoder comprises a linear feedback shift register having one or more flip-flops to generate the check symbols after shifting the message symbols, m0 through mN-1, through the linear feedback shift register. An error correction decoder is also provided for decoding a codeword that includes message symbols, m0 through mN-1, and one or more check symbols. The error correction decoder comprises a linear feedback shift register having one or more flip-flops to generate an error symbol based on a remainder after shifting the message symbols, m0 through mN-1, and the one or more check symbols through the linear feedback shift register.
摘要:
Methods and apparatus are provided for high-speed, low-power, high-performance channel detection. A soft output channel detector is provided that operates at a rate of 1/N and detects N bits per 1/N-rate clock cycle. The channel detector comprises a plurality, D, of MAP detectors operating in parallel, wherein each of the MAP detectors generates N/D log-likelihood ratio values per 1/N-rate clock cycle and wherein at least one of the plurality of MAP detectors constrains each of the bits. The log-likelihood ratio values can be merged to form an output sequence. A single MAP detector is also provided that comprises a forward detector for calculating forward state metrics; a backward detector for calculating backward state metrics; and a current branch detector for calculating a current branch metric, wherein at least two of the forward detector, the backward detector and the current branch detector employ different trellis structures.
摘要:
A pipelined decision feedback unit (DFU) is disclosed for use in reduced-state Viterbi detectors with local feedback. The disclosed pipelined decision feedback unit improves the maximum data rate that may be achieved by the reduced state Viterbi detector by the pipelined computation of partial intersymbol interference-based estimates. A pipelined decision feedback unit is thus disclosed that computes a plurality of partial intersymbol interference based estimates, wherein at least one partial intersymbol interference-based estimate is based on a selected partial intersymbol interference-based estimate; and selects the selected partial intersymbol interference-based estimate from among partial intersymbol interference-based estimates for path extensions into a state.
摘要:
A multicast group list (i.e., destination node address list) for a network device is circularly linked such that the list can be entered at any point and traversed back to the entry point. The list traversal is then terminated as the entire list has been processed. The data packet received at the network device for transmission to the multicast group can indicate the entry point, although there are other techniques for determining the entry point. The destination node address for the entry point is skipped, that is the multicast data packet is not transmitted to the entry point destination address.
摘要:
A method of using an intercom on a cordless telephone during an active call. The active call is put on hold while the intercom is in use. Once the call is re-activated, the intercom is shut off. This system may be designed for a cordless telephone with one handset or a plurality of handsets.
摘要:
A laser assembly comprises a substrate, one or more standoffs and a semiconductor laser. The substrate has a first doped region and a second doped region. The second doped region is proximate to an upper surface of the substrate and forms a pn junction with the first doped region. The semiconductor laser is operative to emit light from an upper surface and a lower surface. Moreover, the semiconductor laser is attached to the upper surface of the substrate with the one or more standoffs such that the light emitted from the lower surface of the semiconductor laser impinges on the second doped region.
摘要:
In one aspect, there is provided a semiconductor device that comprises an interconnect layer located over a semiconductor substrate. A passivation layer is located over the interconnect layer and has a contact support pillar opening formed therein. Contact support pillars that comprise a conductive metal and have a metal extension are located within the opening of the passivation layer.
摘要:
A method for controlling a transmission rate of at least one transceiver, the transceiver including a transmitter and a receiver, includes: determining a signal quality characteristic corresponding to a signal received at the receiver by measuring a difference between one or more reference constellation points and one or more received constellation points, and modifying a transmission rate of the transmitter over a wireless communication channel as a function of the signal quality characteristic. The step of modifying the transmission rate over the wireless communication channel includes: determining lower and upper threshold levels representing reference minimum and maximum signal quality characteristics, respectively, corresponding to the transmission rate; maintaining the transmission rate when the measured signal quality characteristic is between the lower and upper threshold levels; and increasing the transmission rate when the signal quality characteristic is less than one or more lower threshold levels associated with one or more corresponding higher transmission rates.