Abstract: In one embodiment, a method for balancing clock signals in a clock tree includes, at a register, receiving a divided input clock signal and a non-divided input clock signal and generating a first output clock signal based on the received divided input clock signal and the received non-divided input clock signal, the first output signal being associated with a first delay. The method further includes, at a delay line, receiving the non-divided input signal, delaying the non-divided input signal for a time substantially equivalent to the first delay, and generating a second output clock signal associated with a second delay substantially equal to the first delay.

Abstract: A system, apparatus and method are disclosed for implementing a managed network in a hybrid network environment to support nodes having managed network capability together with nodes that do not support managed network capabilities. In one form of the invention, a method for managing data communication on a network coupled to first nodes and second nodes is provided comprising: controlling a first time period for one or more first data transmissions on the network wherein the first nodes are permitted to transmit data during the first time periods and the second nodes are not permitted to transmit data during the first time period by causing the second nodes to treat the first time period as a single transmission period. Other methods, apparatus and systems are provided.

Abstract: The present invention provides a solution that automatically detects and connects the properly terminated line pair and then allows modem training to proceed. The present invention can set a control parameter at the physical layer that establishes a training “state” for the modem (115). Training states can determine whether or not automatic line detection (375) is utilized. Automatic line detection (375) can be accomplished by measuring the power levels (345, 350) on each of the line pairs (145, 150) and then selecting the line pair (145, 150) that has the highest power level measurement (345, 350) as the line on which to continue training the modem (115). The selected line pair (355) can be stored for use as the properly terminated line pair.

Abstract: A reduced search space minimum distance decoding method provides average probability of error performance close to optimal MAP decoding. The decoding algorithm provides dramatic complexity reductions compared with MAP decoding. A a sub-optimal decoder receives a collection of signal vectors y1 . . . yk, with k denoting a positive integer and generates an estimated transmitted multidimensional symbol {tilde over (S)}. The estimated transmitted multidimensional symbol {tilde over (S)} is decoded using hierarchical subset decoding a subset is determined therefrom. A reduced search space V is generated and minimum distance decoding is used to decode the received symbol vectors y1 . . . yk in the reduced search space V. one or more of the following: an estimated multidimensional symbol {tilde over (S)}, soft bit information, or hard bit information are cienerated therefrom.

Abstract: A multi-carrier communications system with a programmable interleaver and de-interleaver that can change the interleaving rate for data transmitted and received in the communications system is presented. The programmable interleaver and de-interleaver permits a level of flexibility in determining the immunity of the communications system to errors and sources of interference. The multi-carrier communications system is able to vary the interleaving rate based on input from a user or from data that it maintains from actual network performance. The multi-carrier communications system can change the interleaving rate during the initial installation of the multi-carrier communications system or whenever the system is reset or restarted or on any individual transmission unit.

Abstract: In digital communications that utilize a data packet format wherein each data packet includes a physical layer (PHY) component and a media access control layer (MAC) component, the media access control layer component can be selectively protected by forward error correction (FEC). The receiving end receives an indication as to whether FEC has been applied, and makes an FEC decision based (12-15) on this indication. The accuracy of the received-side FEC decision and the robustness of the FEC indication can be improved by: making the FEC decision based on the results of FEC decoding applied to a media access control layer header within the media access control layer component; providing an FEC indication bit in the physical layer component; and using a plurality of bits to encode the FEC indication in either the physical layer component or the media access control layer component.

Abstract: In a voice activity detection (VAD) device a method for defining tone signals comprises defining a threshold for zero amplitude change, calculating a zero crossing rate of a signal, extracting a set of parameters from a plurality of duration periods of the signal, defining a tolerance threshold between the plurality of duration periods when a zero amplitude change occurs, calculating a maximum difference between the plurality of duration periods, and comparing the maximum difference with the threshold. The method is implemented in the International Telecommunications Union (ITU) recommendation G.729 Annex B VAD.

Abstract: A communication device (e.g., a modem) is disclosed as including logic that processes a transmit signal before providing a signal to an echo canceler. The processing may include low pass filtering and decimation of the transmit signal. The low pass filter's cut-off frequency preferably is less than the sampling rate associated with the transmit signal.

Abstract: A method is provided to provide data to automatically estimate channel performance in a communication system if a different order constellation is used comprising the steps of: receiving an input signal from the channel; passing the input signal to a slicer having an output signal; determining signal noise by taking the difference between the input signal and output signal; identifying a beginning of a noise event when the signal noise is greater than a predefined first threshold; identifying an end of a noise event when the signal noise is less than a predefined second threshold; and providing for output the beginning of the noise event and the end of the noise event. Other systems and methods are disclosed.

Abstract: The present invention comprises aggregating a plurality of physical channels to a single logical channel, a scalable virtual channel (SVC). This may be implemented in a point to multipoint communications system. The present invention enables a variety of receivers, some receivers being able to receive only one physical channel, and other receivers being able to receive a plurality of physical channels as a SVC, with at least one same channel being used for both types of receivers.

Abstract: A computer method for testing a test unit that includes receiving an output of the test unit into a testing system, providing an expert system operably connected to the testing system, comparing, in the expert system, the output with an expected result for the output, and determining, in the testing system, if the output complies with the expected result. A system for testing a test unit includes a testing module for receiving an output of the test unit, and an expert system for comparing the output with an expected result for the output and for determining if the output complies with the expected result.

Abstract: A four channel wireless network channelization scheme is described that is particularly usable in the ISM frequency band between 2400 MHz and 2483.5 MHz. The preferred channelization scheme permits access points to be set at one of four frequencies in the ISM band, not three as taught by the IEEE 802.11b standard. This channelization scheme takes advantage of the fact that only 20 MHz is typically needed between adjacent access point channels, not 25 MHz as is taught by the 802.11b standard. With four channels to choose from, a higher density of access points can be located thereby accommodating a higher density of users. The four channels preferably are 2407, 2427, 2447 and 2467 MHz. With this selection of channel frequencies and given the current FCC regulations, all four channels can be used to transmit an equal amount of power.

Abstract: A Phased Transmit Architecture that allows the embedded processor of an IEEE 802.11e wireless communication device to have a significant number of additional cycles between decoding of a QoS frame and the deadlines for generating a response transmission.

Abstract: The present invention provides an apparatus, system and method for transmitting asynchronous transfer mode (ATM) data cells on an ATM adaptation layer (AAL) configured connection within an ATM system comprising a digital signal processor (DSP) sub-system (160) and a host processor (190). The transmitter interfaces directly with the DSP sub-system (160) (which converts the digitized voice samples into voice signals) and the host processor (190) (which performs AAL2 signaling and layer management functions). The transmitter is configured to interleave AAL2 voice packets from the DSP sub-system (160) and signaling and management packets from the host processor (190) on an ATM connection. Data is fetched by DMA(s) (415). A channel look-up table uses the DSP assigned voice channel as an index into the table to map a voice channel to the ATM connection.

Abstract: A system and method for detecting a security violation using an error correction code. Some illustrative embodiments may be a method used in a computing system comprising reading a codeword comprising data and an error correction code (ECC) (the ECC associated with the data), deriving an error location polynomial (ELP) from the codeword, determining a total number of codeword errors from the ELP, and preventing access to the data within the codeword if the total number of codeword errors exceeds a maximum number of correctable errors.

Abstract: A method is provided for equalization of nonlinear distortion in a distorted signal comprising the steps of: digitizing the distorted signal and passing the digitized distorted signal through an inverse non-linear transfer function to equalize the nonlinear distortion. Other systems and methods are disclosed.

Abstract: A method for dynamically switching hybrids during modem initialization to maximize channel capacity and performance includes the steps of evaluating each hybrid in the modem according to a cost function dependent on the quiet receive noise floor and the transmit signal echo, and then selecting the hybrid that results in the minimum value for the cost function. By performing these steps, the best available hybrid is selected in order to maximize channel capacity and hence maximize modem performance.

Abstract: In accordance with an embodiment of the present invention an improved equalization system for DMT based modem receiver is provided. It includes a time domain equalizer for processing samples from an analog front end and includes a device for computing differences of time domain samples for every frame and the results are saved. An FFT is provided for calculating a first FFT and the results are saved in a FFT buffer so that at each DMT frame, after a difference and FFT operation, the FFT buffer contains the first FFT and v?1 time domain sample differences. A sliding FFT for each tone reads the first FFT result and v?1 FFTs and recursively computes the rest of v?1 FFTs for the particular tone. An equalizer is responsive to the computed sliding FFT for recursively computes equalizer outputs.

Abstract: A system and method is described for saving power in a wireless network, using a physical layer address filtering protocol based on a partial address subset of the complete destination MAC address. The system comprises a PHY layer filtering protocol for generating the partial address and writing the partial address into a PHY layer header portion (e.g., PLCP header) of a sending station, or reading the partial address from the PHY layer header portion upon transmission of each frame. A receiving station receives and decodes these PHY layer header portion bits, in accordance with the protocol, and compares whether the subset of bits match that of the stations' own partial address. If a station finds a match, the station then continues further decoding the frame at PHY layer and send the complete frame to the MAC layer for further processing. The stations that do not have a match will not activate their MAC layer components.

Abstract: A wireless device (10, 12) is provided that distinguishes between multiple piconets. The wireless device (10, 12) includes a preamble component (160, 162, 164, 166) and a correlator (150) component. The preamble component (160, 162, 164, 166) provides a preamble (120) for a wireless fixed frequency interleaving transmission, and the correlator component (150) distinguishes a wireless transmission based on the preamble (120). A circuit (180) is provided for a wireless receiver to despread a hierarchical sequence (120) made by spreading an M-length sequence (110) with an N-length sequence (112). The circuit (180) includes a first and second despreaders (185, 190). The first despreader (185) is coupled to a signal input to despread a received signal. The signal is a fixed frequency interleaved transmission. The second despreader (190) is coupled to an output of the first despreader (185). The second despreader (190) despreads the output of the first despreader (185) with a second sequence.