Abstract: Provided is a structure for testing a NAND flash memory including a string select transistor, a source select transistor, flash memory cells connected in series between the string select transistor and a source select transistor and a measurement pad coupled to a node between a flash memory cell and the string select transistor or the source select transistor.

Abstract: An array of non-volatiel memory cells arranged in logical columns and logical rows, and associated circuitry to enable reading or writing one or more memory cells on a row in parallel. In some embodiments, the array of memory cells may include a phase change material. In some embodiments, the circuitry may include a write driver, a read driver, a sense amplifier, and circuitry to isolate the memory cells from the sense amplifier with extended refresh.

Abstract: A power-on-reset circuit determines when it is safe for a programmable device to access configuration data from an associated non-volatile memory following a reset operation. The power-on-reset circuit receives a bandgap reference voltage produced by the programmable device. A comparator circuit is used to trigger a self-clocking delay unit when the bandgap reference voltage reaches a threshold level. The self-clocking delay unit generates its own clock signal independent of the clock frequency of the programmable device. The self-clocking delay unit may use edge-dependent delay units in a feedback loop to generate the clock signal. Using its own clock signal, the self-clocking delay unit waits for a predetermined time period and the outputs a signal to be used to enable access to the associated non-volatile memory.

Abstract: A dynamic random access memory (DRAM) is provided that has separate array and peripheral power busing to isolate array noise from peripheral circuits such as delay lock loops during row activations and read/write memory operations. A switch connects the array power bus to another separate power bus for a limited period of time during a DRAM refresh cycle to provide additional current to the DRAM arrays. The switch disconnects the array power bus from the other power bus preferably before the end of the refresh cycle.

Abstract: An apparatus is to reduce, during the standby time, the electric power caused by the leakage current flowing through a storage transistor in a 3-transistor dynamic cell. Source electrodes of storage transistors in a plurality of 3-transistor dynamic cells constituting a memory array are connected, and a switch is provided between the source electrode and a power supply terminal. The leakage current during the standby time is interrupted by bringing the switch into a conducting state during the active time, and by bringing the switch into a nonconducting state during the standby time.

Abstract: An integrated circuit device, a first direction being a direction extending from a first side which is a shorter side of the integrated circuit device to a third side opposed to the first side, a second direction being a direction extending from a second side which is a longer side of the integrated circuit device to a fourth side opposed to the second side, includes: a first to a Nth circuit blocks (N is an integer more than 2) arranged in the first direction. One of the first to the Nth circuit blocks is a programmable ROM block in which at least a part of data programmed is stored by a user; the programmable ROM block includes a plurality of word lines, a plurality of bit lines, and a plurality of memory cells connected to the plurality of word lines and the plurality of bit lines; and the plurality of word lines extend in the second direction.

Abstract: A semiconductor memory device of one aspect includes a memory cell block including n global word lines, and corresponding m sub word lines for each of the n global word lines, where n and m are natural numbers. The memory device further includes a plurality of word line driving circuits which respectively control a voltage of the sub word lines according to a logic level of each corresponding global word line and inputted address signals, and a plurality of control circuits which transmit the address signals to the word line driving circuits or interrupt transmission of the address signals according to the logic level of the global word line. Each of the word line driving circuits includes a first transistor which maintains the voltage of the respective sub word line at a first voltage and a second transistor which maintains the voltage of the sub word line at the first voltage or a second voltage.

Abstract: A semiconductor memory device is provided. The semiconductor memory device includes an active commander for generating an active command upon receiving a plurality of control signals, a first signal generator configured to receive the active command, and generate a first latch signal for latching information associated with activation of the active command, a second signal generator configured to receive the first latch signal and a chip selection signal, generate a word-line activation signal and activation-information signal when the first latch signal and the chip selection signal are simultaneously enabled, and a reset controller configured to receive a second latch signal, the word-line activation signal, and the activation-information signal, and control the first signal generator to reset the first latch signal using the received signals.

Abstract: A data input device for use in a semiconductor memory device includes a synchronization control unit for receiving a data strobe signal with which a data is synchronized in order to generate a synchronization signal in response to a driving signal; and a synchronization unit for storing internal data input sequentially one-bit by one-bit into a plurality of synchronous storing elements and asynchronous storing elements and for outputting the stored data as parallel-typed aligned data all at once in synchronization with the synchronization signal.

Abstract: A method for accessing a memory sequentially. The memory has (m+1) bit lines and at least one row of transistors, wherein m is a positive integer. This method includes the following steps. First, voltage levels of first and second terminals of the transistors are equalized to a ground voltage in a pre-discharge period. Next, the voltage levels of the first and second terminals of the nth transistor are respectively transformed into a source voltage and a drain voltage in an nth reading period, and the voltage level of the second terminal of the (n+1)th transistor is transformed into an isolation voltage, wherein n is a positive integer smaller than m. Thereafter, the voltage levels of the first and second terminals of the mth transistor are respectively transformed into the source voltage and the drain voltage in an mth reading period. The source voltage equals the ground voltage.

Abstract: According to a preferred aspect of the instant invention, there is provided a system and method for acquiring seismic data in a marine environment, wherein at least two source vessels are used in conjunction with a recording vessel which tows a plurality of hydrophone cables. Preferably, the source vessels will be positioned along side of the towed streamer configuration and most preferably one source vessel will be located near the recording vessel and the other at the end of the streamer configuration, preferably along the same side of the streamer configuration as the lead source vessel.

Abstract: Methods and systems for estimating one or more orientation parameters of a seismic apparatus are described. One method comprises initiating an acoustic signal from an acoustic transmitter in a marine seismic spread comprising a streamer, the streamer having at least two nodes separated by a fixed distance; measuring a first and a second difference in acoustic arrival times at the nodes for the acoustic signal; and using change in the second difference from the first difference to estimate orientation of the streamer. It is emphasized that this abstract is provided to comply with the rules requiring an abstract, which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

Abstract: The present invention provides methods and systems for microseismic hydraulic fracture monitoring in real-time. The methods and systems of the present invention may include continuous map migration of recorded microseismic signals. The methods and systems provide robust automated simultaneous detection and location of microseismic events.

Abstract: A lithographic apparatus comprises an illumination system, a support constructed to support a patterning device, and a projection system. In pixel grid imaging, a large number of small optical spots are imaged onto the substrate surface using a micro-lens array (MLA). The z position of the MLA is adjustable in order to focus the spots on the substrate surface and/or to compensate for differences in height of the substrate surface. The focusing adjustment is based on an output of an ultrasonic distance sensor provided in the vicinity of the substrate surface.

Abstract: A positioning device has a reception unit for receiving navigation messages transmitted continuously in a time series from positioning information satellites orbiting the Earth and determines the location of the positioning device based on the navigation messages received by the transmission unit. Each navigation message is segmented into a plurality of data transmission blocks that are transmitted sequentially, a portion of the data transmission blocks carry almanac data containing orbital information for all positioning information satellites including the positioning information satellite transmitting the received navigation message, and the data transmission blocks carrying the almanac data are transmitted non-contiguously. The positioning device also has signal discrimination unit for identifying the start of receiving a data transmission block containing the non-contiguously transmitted almanac data, and identifying the end of receiving the data transmission block containing the almanac data.

Abstract: An information recording medium having at least a read only area and a recording and reproducing area is composed of at least: a substrate; a recording layer formed on the substrate so as to record and reproduce information; and a light transmission layer having transparency formed on the recording layer. The information recording medium is further characterized in that a wobbling groove corresponding to the read only area and another wobbling groove corresponding to the recording and reproducing area is formed on the substrate without overlapping with each other, the recording and light transmitting layers are continuously adhered over at least two areas of the read only area and the recording and reproducing area, reflectivity of the recording layer is more than 5%, and a push-pull signal output T3 reproduced from the read only area and another push-pull signal output T4 reproduced from the recording and reproducing area before recording satisfies relations of T3?0.1, T4?0.1 and 1.5?T3/T4?0.5.

Abstract: An information recording medium having at least a read only area and a recording and reproducing area is composed of at least: a substrate; a recording layer formed on the substrate so as to record and reproduce information; and a light transmission layer having transparency formed on the recording layer. The information recording medium is further characterized in that a wobbling groove corresponding to the read only area and another wobbling groove corresponding to the recording and reproducing area is formed on the substrate without overlapping with each other, the recording and light transmitting layers are continuously adhered over at least two areas of the read only area and the recording and reproducing area, reflectivity of the recording layer is more than 5%, and a push-pull signal output T3 reproduced from the read only area and another push-pull signal output T4 reproduced from the recording and reproducing area before recording satisfies relations of T3?0.1, T4?0.1 and 1.5?T3/T4?0.5.

Abstract: A optical pickup system for use in a disk drive includes a stepping motor, a lead screw supported by a bracket and coupled to the stepping motor, in which the lead screw has spiral grooves formed on an outer periphery of the lead screw and engaged to a slider to move an optical pickup head in a radial direction of a disk, a plurality of guide shafts, installed to a main base in parallel with the lead screw, for guiding the optical pickup head in the radial direction of the disk, and a positioning mechanism for supporting the bracket which is installed to the main base to move in any direction to automatically maintain a position of the lead screw to the slider, thereby minimizing a load applied to the stepping motor.

Abstract: An information recording medium having at least a read only area and a recording and reproducing area is composed of at least: a substrate; a recording layer formed on the substrate so as to record and reproduce information; and a light transmission layer having transparency formed on the recording layer. The information recording medium is further characterized in that a wobbling groove corresponding to the read only area and another wobbling groove corresponding to the recording and reproducing area is formed on the substrate without overlapping with each other, the recording and light transmitting layers are continuously adhered over at least two areas of the read only area and the recording and reproducing area, reflectivity of the recording layer is more than 5%, and a push-pull signal output T3 reproduced from the read only area and another push-pull signal output T4 reproduced from the recording and reproducing area before recording satisfies relations of T3?0.1, T4?0.1 and 1.5?T3/T4?0.5.

Abstract: A system, method, computer program and apparatus for providing regulating signals for regulating the position of an objective lens relative to a track on a disk. The regulating signals are obtained in response to an access request specifying an access target region on the disk. The tracks of a disc are divided into a plurality of zones, each zone having associated signal regulation information. In response to an access request, the signal regulation information for the zone containing the access target region is used to regulate the position of the objective lens.

Abstract: An apparatus and a method for reducing a lead-in time of a disc, on which data is always recorded, and detecting exactly a tilt of the disc. The apparatus includes a pickup, and a system controller. Even if the disc is a blank disc which is devoid of user data, control data is recorded on the disc. The pickup can record data on the disc or reproduce data from the disc. If a seek command is received, the system controller detects the tilt of the disc once in each of a plurality of zones while the pickup is moving.

Abstract: In a processing section 4, allowable gain-value range defining unit 41 measures a gain value k corresponding to a level ratio between an MPP signal and an SPP signal generated by a tracking error signal generating circuit 3 to define an allowable range of the gain value, and eccentricity measuring unit 42 measures an eccentricity of an optical disk. If the eccentricity is determined to be greater than or equal to a predetermined value by eccentricity determining unit 43, gain-value defining unit 44 selects a minimum value of the gain value k to define the minimum value as a gain value k of an amplifier 37. On the other hand, if the eccentricity is determined to be less than the predetermined value, the gain-value defining unit 44 selects a central value of the gain value k to define the central value as the gain value k of the amplifier 37.

Abstract: A recorder provides to a recorder/player via a high-speed bus content-related information such as a digital audio signal as information, a content ID being identification information on the digital audio signal and a standard playing time of the digital audio signal. The recorder/player has a controller which stores the content ID into a copy-history information management memory when the same content ID is not existent in the memory. The content ID is held for a period measured by a timer. For this period, the recording function of the recorder/player is limited so that the same digital audio signal cannot be copied at a high speed.

Abstract: There is provided an optical disc having preformed thereon a spiral wobbled track as a grove and/or land along with data is to be recorded. The track is wobbled for a series of predetermined signal units each composed of an FSK information bit part based on a waveform resulted from FSK modulation of information bit and a singe-frequency part based on a waveform of a single frequency. The FSK modulation uses two different frequencies of which the one is the same as the single frequency and the other is different from the single frequency. These different frequencies are in such a relation that each of them has an even number of wobbles and an odd number of wobbles alternately in a predetermined cycle.

Abstract: A method of determining a recording power for a recordable optical disk in an optical disk system is provided. The method is capable of minimizing the time taken to determine an optimum recording power for each recording speed and thus improve recording performance.

Abstract: A storage medium and method for managing a defective area of the storage medium are provided. The method includes (A) identifying a defective area found during recording or reproducing of data; (B) writing the data intended for the defective area in any part of a user area that is unused, wherein the storage medium is without any pre-designated spare area so that the entire user area corresponds to an entire data area of the storage medium; and (C) writing positional information about the defective area in the user area.

Abstract: A write once disc includes a defect management area that is present in at least one of a lead-in area and a lead-out area; a temporary defect management area that is present in at least one of the lead-in area and the lead-out area; and a drive & disc information area that is present in at least one of the lead-in area and the lead-out area. Information regarding the locations of temporary defect information and temporary defect management information is recorded in the drive & disc information area, the temporary defect information and temporary defect management information, which includes drive & disc information, are recorded in the temporary defect management area, and temporary defect information and temporary defect management information, which are lastly recorded in the temporary defect management area, are recorded in the defect management area for disc finalization.

Abstract: A write once disc allowing management of a data area, includes a lead-in zone, a data area, and a lead-out zone. The write once disc includes a predetermined area storing area allocation information which indicates whether at least one section of the data area is allocated for disc defect management. In the disc and method, area allocation information specifying a structure of the data area is recorded on the disc, thus allowing a recording/reproducing apparatus to recognize the data area structure. Therefore, allocating areas, such as a spare area, for disc defect management other than an area for storing user data, to the data area is possible. The allocation of the areas for disc defect management to the data area enables effective use of the write once disc.

Abstract: In one embodiment, a disc has a substrate; a data layer on the substrate; an anomaly-feature in the data layer disc capable of generating a read anomaly having a predictable anomaly profile; and anomaly profile data recorded in the data layer for characterizing the anomaly-feature. A disc can be labeled by imposing an anomaly-feature in the data layer capable of generating a read anomaly having a predictable anomaly profile; and disposing anomaly profile data on the disc, wherein the anomaly profile data characterizes the anomaly-feature.

Abstract: A disk apparatus includes a light emitter that emits a light beam to be reflected on the optical disk, a light detector that detects a reflected light beam that is reflected from the optical disk, the light detector also outputting detection signals based on the amount of the reflected light beam detected, and a controller determines whether the optical disk is a recordable optical disk or not based on the detection signals. The controller also shifts a spot on the light detector at which the reflected light beam is incident by adjusting the focus point of the light beam on the optical disk in the radial direction when the controller determines that the optical disk is not a recordable optical disk. A wobble signal can be detected with high precision at low cost even when the position of the light detector is not balanced in the radial direction.

Abstract: An information provision apparatus has a detachable information storage medium that stores information, an information storing portion that storing information read from the information storage medium, a processing portion that performs a reproduction processing of information stored in the information storing portion, an output portion that outputs information reproduced by the processing portion, and a clocking portion that counts an elapsed time since the information storage medium is detached from the information provision apparatus, wherein the processing portion stops the reproduction processing when the elapsed time exceeds a specified value.

Abstract: Compatibility information embedded in an optical medium modifies actions allowed by predetermined non-compatible optical disc drives on the optical medium, such as optical disc drives that may suffer damage if certain actions are performed on the optical medium. For instance, a compatibility engine of the optical disc drive applies compatibility information read from an optical medium to determine restrictions to impose on the use of the optical medium, such as restricting the optical disc drive from writing to the optical medium, reading from the optical medium or performing any operations until an update to the optical disc drive firmware is performed either automatically or by display of a compatibility user interface at an information handling system associated with the optical disc drive. In one embodiment, the compatibility information identifies incompatible optical disc drives and firmware versions by unique identifiers.

Abstract: The mark-length recording system whereby information is recorded by changing the lengths of a recorded portion and an unrecorded or erased portion has a problem that, when new information is recorded in an already recorded region, the newly recorded information may deteriorate in reliability because the length and width of the newly recorded mark are different from those of the previously recorded mark and a part may exist that is not completely erased at the time of overwriting. The invention widens a setting freedom of the recording power and controls the length and width of the recorded mark by making the effective recording pulse length (the length from a rise of a first pulse to a fall of a last pulse) satisfy a relation: (effective recording pulse length)<(recording code length, i.e., the length of data to be recorded)?2T(twice the reference clock cycle).

Abstract: An adaptive writing method of a high-density optical recording apparatus and a circuit thereof. The circuit includes a discriminator for discriminating a magnitude of a present mark of input NRZI data and magnitudes of leading and/or trailing spaces of the input NRZI data, a generator for controlling the waveform of a write pulse in accordance with the magnitude of the present mark of the input NRZI data and the magnitudes of the leading and/or trailing spaces of the input NRZI data to generate an adaptive write pulse, and a driver for driving a light source by converting the adaptive write pulse into a current signal in accordance with driving power levels for respective channels of the adaptive write pulse. The widths of the first and/or last pulses of the write pulse waveform are varied in accordance with the magnitude of the present mark of input NRZI data and the magnitude of the leading and/or trailing spaces, thereby minimizing jitter to enhance system reliability and performance.

Abstract: An adaptive writing method of a high-density optical recording apparatus and a circuit thereof. The circuit includes a discriminator for discriminating a magnitude of a present mark of input NRZI data and magnitudes of leading and/or trailing spaces of the input NRZI data, a generator for controlling the waveform of a write pulse in accordance with the magnitude of the present mark of the input NRZI data and the magnitudes of the leading and/or trailing spaces of the input NRZI data to generate an adaptive write pulse, and a driver for driving a light source by converting the adaptive write pulse into a current signal in accordance with driving power levels for respective channels of the adaptive write pulse. The widths of the first and/or last pulses of the write pulse waveform are varied in accordance with the magnitude of the present mark of input NRZI data and the magnitude of the leading and/or trailing spaces, thereby minimizing jitter to enhance system reliability and performance.

Abstract: An adaptive writing method of a high-density optical recording apparatus and a circuit thereof. The circuit includes a discriminator for discriminating a magnitude of a present mark of input NRZI data and magnitudes of leading and/or trailing spaces of the input NRZI data, a generator for controlling the waveform of a write pulse in accordance with the magnitude of the present mark of the input NRZI data and the magnitudes of the leading and/or trailing spaces of the input NRZI data to generate an adaptive write pulse, and a driver for driving a light source by converting the adaptive write pulse into a current signal in accordance with driving power levels for respective channels of the adaptive write pulse. The widths of the first and/or last pulses of the write pulse waveform are varied in accordance with the magnitude of the present mark of input NRZI data and the magnitude of the leading and/or trailing spaces, thereby minimizing jitter to enhance system reliability and performance.

Abstract: Disclosed herewith is an information reproducing method for realizing significant expansion of disk capacity and processing signals having different minimum run lengths, as well as an optical disk drive that uses the method. To achieve the above objects, a PRML method is used. According to the method, a compensation value is added to an initial target value decided by a convolution operation of NN bits according to a bit array consisting of N bits (N>NN) to obtain a new target value, which is then compared with each of reproduced signals sequentially to select a bit array in which the error between the reproduced signal and the target signal is minimized most likely, then the selected bit array is binarized.

Abstract: Optical pick-up apparatus for retrieving data stored on an optical storage disc having a plurality of record layers (6, 7), the radiation beam reflected back from the disc when a first layer (7) is irradiated comprising radiation reflected back from the first layer (7) and radiation reflected back from one or more of the other layers(6). A spatial filter (8) is provided which is arranged and configured to spatially filter the radiation beam so as to cause the radiation reflected by the first record layer (7) and the radiation reflected by any of the other record layers (6) of the optical storage disc to be spatially separated, such that at least a substantial portion of the radiation reflected back from the other layers (6) can be selectively eliminated from the radiation beam prior to retrieval therefrom of the data.

Abstract: Methods and systems for formatting of optical media used for data or information storage.

Abstract: In an optical information recording/reproducing apparatus using holography in which a relative inclination between a recording light or a reproducing light and a recording medium is corrected by using a device which is suitable for size-reduction. Provided is an optical information recording/reproducing apparatus for recording/reproducing information to/from a recording medium through irradiating recording light or reproducing light by an objective lens onto a recording medium to/from which information is recorded/reproduced using holography, wherein light ray flux of the recording light or the reproducing light entering an objective lens is parallel-translated according to a relative inclination between the recording light or the reproducing light and the recording medium.

Abstract: Methods for recording volume Bragg grating structures having a target wavelength are disclosed. Such a method may include providing a photosensitive recording medium, bringing a first face of the recording medium into contact with a face of a prism, the prism being made of a material that is transparent at a recording wavelength, and recording a Bragg grating onto the recording medium by exposing the prism to an incident light wave at the recording wavelength.

Abstract: An optical pickup device includes a light source to emit light, an objective lens to focus the light on a recording medium to form a light spot, an optical path changer on an optical path between the light source and the objective lens to change the path of incident light, a chromatic aberration correction lens disposed on an optical path between the light source and the objective lens, and a photodetector to receive light which is reflected from the recording medium and is then incident thereon through the optical path changer. The chromatic aberration correction lens corrects a chromatic aberration occurring due to a change in the wavelength and/or due to an increase in a wavelength bandwidth of the light. The chromatic aberration correction lens includes at least two lenses such that a lens having a positive power and a lens having a negative power are adjacent to each other.

Abstract: An optical information recording method records information with respect to an optical information recording medium having a multi-layer structure recording layer formed by a plurality of recording layers each capable of recording information, and carries out an Optimum Power Control (OPC) prior to carrying out the recording. Recording conditions that are used when carrying out the OPC are read from one of the recording layers of the optical information recording medium to which the recording is to be made, where each of the recording layers is recorded with the recording conditions therefor, and the OPC is carried out using the read recording conditions.

Abstract: A data storage device includes a conductive probe having a tip; a substrate; and a data storage medium including a layer of poled ferroelectric material. The ferroelectric layer is between the tip and the substrate.

Abstract: A memory apparatus comprises a media, a tip adapted to write information to and read information from said media, a media movement mechanism attached to said media and configured to move said media in response to media control signals, and a capacitive sensor configured to detect an amount of relative movement of said media and said tip in at least an x-axis direction. The capacitive sensor includes a fixed comb having fingers protruding in an x-axis direction, a moving comb connected having fingers protruding in an x-axis direction, and an electrical path connected to said fixed comb and an electrical path connected to said moving comb. The relative movement in at least the x-axis direction is determined at least in part on a change in capacitance between said fixed and moving combs of said capacitive sensor.

Abstract: The present invention provides a technique for improving reliability of reading header information. The optical disk is composed of a recording track. The recording track includes a data recording region in which recording pits are formed for recording data, and a header region in which pre-pits are formed for recording header information identifying said data recording region. Said recording pits have a reflectance smaller than that of a space in which said recording pits are not formed. Said recording pits and said pre-pits are formed so that an amplitude (dynamic range) of a level of an optical signal reflected from said header regions is larger than that of an optical signal reflected from said data recording regions.

Abstract: An information recording carrier in one mode has minute pattern including plural grooves or lands formed in parallel and adjacent each other and comprises a supporting body having the minute pattern, a recording layer formed on the minute pattern, and a light transmission layer formed on the recording layer. The minute pattern is formed under a relation of p<?/NA, where a pitch of each groove or land is P, a wavelength of a laser beam is ? and a numerical aperture of an objective lens is NA. The plural grooves or lands have at least a wobbling region where data is recorded wobblingly by frequency shift modulation. A phase relation between the high and the low frequency portion composing the frequency shift modulation is ±(?/2.5) and the high and the low frequency portion are continuous in phase at a border between the high and the low frequency portion.

Abstract: A method for determining layers in a recording medium having a plurality of layers for the recording and reproduction of information using light irradiation. Each of the plurality of layers includes an emboss portion and a wobble region having wobbles of a predetermined frequency. Layer determination is carried out based on the ratio of the amplitude of a wobble signal obtained from the wobble region to the amplitude of a reproduction signal from the emboss portion.

Abstract: Methods and systems for adaptive modulation are provided. In one embodiment, a method for a plurality of remote units of an orthogonal frequency division multiplexing multipoint-to-point communications system comprises: establishing communication between a plurality of remote units and a host unit, the plurality of remote units communicatively coupled to the host unit in a multipoint-to-point configuration; transmitting a plurality of tones from the plurality of the remote units such that tones from more than one remote unit are simultaneously received at the host unit, the plurality of tones modulated with upstream information using orthogonal frequency division multiplexing; modulating up to a plurality of tones using a first modulation scheme when transmitting a first type of upstream information; and modulating up to a plurality of tones using a second modulation scheme when transmitting a second type of upstream information.

Abstract: Methods and systems for forward-looking tone allocation are provided. In one embodiment, a method for an orthogonal frequency division multiplexing (OFDM) multipoint-to-point communications system comprises: establishing communication between a plurality of remote units and a host unit, the remote units communicatively coupled to the host in a multipoint-to-point configuration; transmitting a plurality of tones from the remote units, such that tones from more than one remote unit are simultaneously received at the host, the tones modulated with upstream information using OFDM; adjusting at least one characteristic of at least one tone at least one remote unit, in response to adjustment commands from the host, such that the orthogonality of the simultaneously received tones is improved as received at the host unit; and dynamically switching modulation from at least a first tone of the plurality of tones to a second tone based on an error-rate history of the second tone.