Abstract: A simultaneous broadcasting system, a transmitter, and a receiver therefor use a first frequency bandwidth for a wide area broadcasting and a second frequency bandwidth for a local area broadcasting obtained by dividing a frequency bandwidth of one broadcasting channel. In the simultaneous broadcasting system, a same program for the wide area broadcasting is transmitted based on an OFDM modulation method by using the first frequency bandwidth and a different program for each local area station is transmitted by using a different spreading code allocated for each local are station based on a SS modulation method.

Abstract: A communications apparatus and a frequency control method thereof, in that control of a reference frequency (local oscillator frequency) is made by feeding back a frequency offset estimate FOS to the voltage-controlled oscillator 103, and the frequency offset between sending and receiving frequencies is corrected by feeding back a frequency offset control value FOC which is based on a sending reference frequency command on downstream control data DCD to sending frequency offset control means 118, to control a sending reference frequency by using both a voltage-controlled oscillator 108 (a frequency control step) and sending frequency offset control means 118 (a sending frequency offset control step).

Abstract: A method and system of communicating in free space using an optical communication system, such as for intersatellite and satellite-to-ground communications, is disclosed. Digital communication signals are multiplexed with a plurality of other analog communication signals into a single broad band frequency division multiplexed signal. A laser generates an optical carrier and an electro-optic modulator modulates the optical carrier signal with the frequency division multiplexed signal to produce a phase modulated optical communications signal. A receiver is positioned, such as in a satellite, to receive the phase modulated optical communications signal. The receiver includes a demodulator for demodulating the phase modulated optical communication system back into the broad band frequency division multiplexed signal and a demultiplexer for demultiplexing the broad band frequency division multiplexed signal into the plurality of communication signals.

Abstract: The present invention relates to a parallel combinatory CDMA (PC-CDMA) system that transmits and receives data by applying a predetermined pseudo number (PN) code corresponding to a plurality of bits, and more particularly relates to a multi-carrier PC-CDMA system, enhancing its efficiency by mixing the PN codes corresponding to the plurality of bits with respective orthogonal frequencies. The transmitting part includes a plurality of mixers 331 to 33n for mixing respective PN codes outputted from a plurality of mappers 321 to 32n with frequency signals having an orthogonal feature and a receiving part including a plurality of mixers 411 to 41n for mixing received signals with the same frequency signals mixed at the transmitting part. Accordingly, it is possible to decrease the number of PN codes needed in a PC-CDMA system by correlating the mappers 321 to 32n of the transmitting part and correlator 421 to 42n and data detectors 431 to 43n of the receiving part through the mixers 33 and 41 independently.

Abstract: A multi node network communications protocol which provides high information throughput at high efficiency, while also maximizing low probability of detection and interception characteristics by optimizing use of transmitting power and other characteristics including but not limited to modulation method, FEC rate and spread spectrum processing gain. The network is optimized by dividing into sub-networks and optimizing the sub-networks to consider local conditions, thus optimizing the overall network to a level of efficiency not possible from a central control point. A protocol which periodically adapts to changing conditions and allows silent entry and exit of nodes as well as providing locations of all nodes within the network.

Abstract: In a GSM (Global System for Mobile communications) system, a lookup table used to scramble intermediate results in a pseudorandom fashion is also used to uniquely associate radio facilities with one another, particularly to associate mobile stations with a base station. Several different lookup tables (RNTBLi) may be used which are uniquely assigned to the radio facilities, with the intercommunicating radio facilities being assigned the same lookup table. The different lookup tables are preferably generated on the basis of subscriber identifications, whereby each subscriber is assigned a respective one of the lookup tables.

Abstract: A communication apparatus having a master device connected with a plurality of outside lines and a plurality of slave devices wirelessly connected with the master device, the communication of the communication data between the master device and the plurality of slave devices being performed for each communication frame on the basis of the spread spectrum communication method, the communication apparatus further having, the master device having: an allocation device for dividing the communication frame into at least a first slot and a second slot, for allocating the first slot to the communication data to be used for performing a first communication between the master device and a first slave device among the plurality of slave devices, and for allocating the second slot to the communication data to be used for performing a second communication between the master device and a second slave device among the plurality of slave devices; and a second communicating device for performing simultaneously the first comm

Abstract: The method according to the invention relates in general to transmission in cellular telecommunication systems and in particular to optimization of the data transfer mode. In the method according to the invention the data transfer mode is controlled using the downlink quality measured by the mobile station (MS) and the uplink quality measured by the base station (BTS). For transparent connections it can be determined a desired maximum threshold for the RXQUAL value, and when the uplink or downlink RXQUAL exceeds that maximum threshold (ie. the bit error rate BER exceeds the maximum value), a more error-tolerant channel coding of a lower transmission speed is taken into use and the channel resources available are increased e.g. by growing the number of time slots to keep the user data transmission rate constant.

Abstract: The establishment of an interactive broadcasting network requires not only a transmission channel from transmitter to receiver but also a transmission channel from receiver to transmitter. A novel method of creating a data feedback channel from receiver to transmitter is implemented in a common frequency network and involves the use of a transmission procedure in conformity with the DAB standard. Each receiver or user is assigned an identifier which is transmitted in the data feedback channel at specially reserved frequencies to request transmission capacity. A computer then allocates transmission capacity to the receiver. The signals received in the forward channel are evaluated using the synchronization symbols they contain in order to synchronize the transmitter component in the receiver. The novel process can be used in all common frequency networks which use data transmission in conformity with the DAB standard and ensures a particularly economical synchronization in the receiver.

Abstract: A communications apparatus is adapted for use with a mains electricity transmission and/or distribution network. The communications apparatus includes a signal transmission and/or reception means, and frequency conversion means for converting the frequency of a signal transmitted or received by the signal transmission and/or reception means to a frequency which facilitates improved propagation of the signal on the network. Preferably the signal transmission and/or reception means is adapted to operate according to a telephony standard with uses a relatively high carrier frequency (e.g. CT2), and the frequency conversion means is usable to covert a signal having a relatively high carrier frequency (e.g. CT2) and the frequency conversion means is usable to convert a signal having a relatively high carrier frequency to a signal having a lower carrier frequency.

Abstract: A Time Division Multiple Access FDD/TDD dual mode system includes a switch having first and second common terminals and first and second terminals. Also included are a TDD demodulation circuit for demodulating a TDD received signal from the first common terminal; a FDD demodulation circuit for demodulating a FDD received signal; and a FDD/TDD modulation circuit for modulating and impressing the modulated signal onto the second common terminal. A FDD transmission band selection circuit is connected to the first terminal, and a TDD transmission-reception band selection circuit is connected to the second terminal. The first common terminal of the switch is connected to the second terminal during TDD reception, whereas the second common terminal is connected to the first terminal during FDD transmission and to the second terminal during TDD transmission.

Abstract: A node controller (30) within a data communication network (22) provides network access for a digital data stream (32). A processor (42) partitions the digital data stream (32) into a constant data rate component (44) having a predictable data rate and a data packet component (46) having an unpredictable data rate. The constant data rate component (44) is then transferred over a first portion (74) of a network data stream (26) reserved for a circuit transmission protocol, and the data packet component (46) is packetized and transferred over a second portion (76) of the network data stream (26) reserved for a packet transmission protocol.

Abstract: When radio communication units communicate with each other, communication is performed using a hopping pattern obtained by shifting a hopping pattern that is used in communication between a radio control unit and the radio communication units.

Abstract: A method for multiple users accessing a common channel in which coded application bits are generated and transmitted for a plurality of applications for a plurality of users. A plurality of tones are assigned to the coded application bits for each application. The coded application bits for each application are encoded into multitone symbols at a transmitter using the plurality of tones assigned to the coded application bits. The multitone symbols for each application are synchronized for transmission on a common uplink channel. At a receiver, the multitone symbols for each application are received from the common channel and tone decoded into the coded application bits for each application using the plurality of tones assigned to the coded application bits. The coded application bits are then decoded for each application.

Abstract: An initial synchronization method in a code division multiple access reception system for determining a pseudonoise (PN) code received in the system by receiving a signal corresponding to an interval of the PN code in a window size, determining representative values of corresponding ones of PN code chips in the window, respectively, and determining the representative values as chips of the PN code, comprising the steps of selecting n successive PN code chips having the same offset in each interval of the PN code, deriving mn (m<n) phase differences of the successive PN code chips in each interval of the PN code, and continuously deriving subsequent PN code chips, thereby deriving n PN code chips, and deriving representative values of n chips of the PN code, based on corresponding ones of the PN code chips derived in all intervals of the PN code, respectively, thereby determining the PN code. In order to verify the initial synchronization, a first PN code signal derived in the above procedure is used.

Abstract: A method and apparatus for varying the data transmission rate of a code division multiple access (CDMA) telecommunications system. The method and apparatus may be implemented into an existing system operating according to a standard designed for a base data transmission while utilizing the Walsh modulator length, the data transmission frame structure, the channel encoding scheme, or the I/Q modulation level of the existing system. Serial data is input to a transmitter/modulator at a data rate which is higher than the base data transmission rate. The serial data is received over a time period having a duration equal to the duration of the transmission frame and demultiplexed into a plurality of sets of input data. Each of the plurality of sets of input data is then processed in one of a plurality of subchannels using the system channel encoding and interleaving scheme to generate a plurality of sets of processed data.

Abstract: A multicarrier transmission system (100) routes data symbols from a data source (142) to a multicarrier modulator (145). Each modulator (201, 202, 203) within the multicarrier modulator (145) is coupled to a corresponding gain adjuster (211, 212, 213) that distributes the available transmit power across various subcarriers. Power distribution, is determined in part, upon the noise sensitivity of the transmitted information. In accordance, data stream symbols of like sensitivity are grouped (520) and transmitted during defined time intervals. Each such group is assigned a unique transmission power level (530). At any given moment in time, all subcarrier transmission power levels will have an identical amplitude, thereby mitigating the impact of subchannel-to-subchannel interference.

Abstract: A swept frequency communication system includes a modulator that multiplies a frequency sweep signal with one or more underlying modulated communication signals to produce a swept frequency signal having a number of headerless tracks located directly adjacent one another in the swept frequency/time domain. A demodulator receives the swept frequency signal after that signal has been passed through a wireless channel, isolates a particular track of the received swept frequency signal to prevent a near/far problem, A/D converts the isolated track, resweeps the digitized isolated track, and then equalizes the isolated track using a blind channel equalizer to eliminate time-varying amplitude/phase impairments caused by transmission of that track through the wireless channel. The demodulator then removes the sweep signal from the equalized swept frequency track and decodes or demodulates the underlying modulated communication signal.

Abstract: A single counter dual modulus frequency divider apparatus (400) utilizes a programmable divider (508) configured to receive an RF input signal at the divider system input (500) and a modulus control (516) produced by a programmable counter (510). The modulus control (516) sets a divide value of the programmable divider (508) to produce a divided signal at a programmable divider output (514). A switch (512) is configured to receive a first program instruction at the first program instruction input (504) and a second program instruction at a second program instruction input (506) to produce a count control (518). The programmable counter (510) receives the divided signal appearing at the programmable divider output (514) and the count control (518). The count control (518) sets the count value of the programmable counter (510).

Abstract: In a wireless communication system in which a base station communicates with plural mobile stations using a control channel and plural voice (or data) channels, the present invention uses the control channel as a voice channel whenever the other voice channels are in use and a request is received from a mobile station for another voice channel. The base station's use of the control channel varies as the control channel switches from a control channel to a voice channel and back to a control channel again.

Abstract: A system and method for optimizing usage of a communications transmission medium. The transmission medium may be sliced into time and frequency domains so as to create time-frequency slices for assignment to users having varying access rates and user-application requirements. Through scheduling of the various speed users within the frequency and time domains, the system and method can efficiently allocate and make use of the available spectrum, thereby accommodating higher rate users requiring greater bandwidths and time slot assignments while still preserving cost-efficient access for lower speed users. Depending on the signal modulation scheme, the time-frequency slices may be allocated on non-contiguous frequency bands. The system and method is also applicable to code-division multiple access (CDMA) techniques by slicing the available code space along time-code domains, frequency-code domains or, in three dimensions, along time-frequency-code domains.

Abstract: A first control channel associated with a first cell is communicated in the first cell using a first time/frequency window. The first control channel and a traffic channel are communicated in a second cell using the first time/frequency window. The first control channel may be communicated in the second cell when the first time/frequency window is unassigned to a traffic channel in the second cell. The first time/frequency window may be assigned to a traffic channel in the second cell, and the first control channel may be communicated in the second cell when the traffic channel to which the first time/frequency window is assigned in the second cell is idle. The traffic channel to which the first time/frequency window is assigned in the second cell may be communicated over different carrier frequency bands to thereby frequency hop the traffic channel.

Abstract: A transmultiplexer is connected between digital facilities and analog facilities for translating information between TDM and FDM formats on the digital and analog facilities, respectively. Information in the TDM format is representative of a plurality of digital telephone signal channels and information in the FDM format is representative of a plurality of analog telephone signal channels. The total capacity of the digital facilities is smaller than the total capacity of the analog facilities. Any one of the digital channels can be selectively coupled to any one of the analog channels. The transmultiplexer is installed at a telephone central office facility as an interface between a cable telephony transmission system and a digital telephone switch. A host computer controls both the transmultiplexer and the digital telephone switch.

Abstract: A method and system are disclosed for enabling point-to-point and multicast communication in a network using three types of communication channels, namely, one or more upstream payload channels, one or more upstream control channels and one or more downstream channels. At least the upstream control and upstream payload channels can carry bitstreams simultaneously; a bitstream may be simultaneously carried on the upstream control and upstream payload channels of a shared medium during overlapping periods of time. Each channel illustratively is divided into slots or mini-slots. Each upstream payload channel is assigned for carrying upstream directed payload bitstreams from stations to a central controller. Each upstream control channel is assigned for carrying upstream directed control bitstreams, such as reservation request bitstreams requesting reservation of time slots of the upstream payload channel, from the stations to the central controller.

Abstract: A method of radio frequency communications between a first unit and a second unit. The method includes the steps of transmitting during a first time interval over a first frequency by the first unit, receiving during the first time interval over the first frequency by the second unit, transmitting during a second time interval over a second frequency by the second unit, receiving during the second time interval over the second frequency by the first unit. The method also includes the step of setting a select frequency shift between the first frequency and the second frequency. In one application of the method, the first unit is a cordless telephone hand set and the second unit is a cordless telephone base station. The method is particularly effective when the first unit and the second unit operate in TDD mode.

Abstract: A system and method are described for assigning downstream and upstream communication pathways in broadband access networks, such as networks based on the hybrid fiber-coax architecture. In the upstream direction, frequency channel and time slot assignments use a packing opposite methodology, which is dependent on the type of service request. The system assigns the lowest time slot in the lowest frequency available for a DSO service request and the highest time slot in the highest frequency which has the next four contiguous time slots available for an H0 service request. To optimize upstream bandwidth efficiency, a H0 channel occupying the space of four contiguous time slots is used to carry up to six simultaneous voice conversations. A method is described that governs such use of H0 channels by NIUs according to their offered loads.

Abstract: An FDMA (Frequency-Division Multiple Access) transmitter-receiver for use in an FDMA communication system which is capable of changing a bandwidth of a channel as required.

Abstract: A digital receiver apparatus and method, designed for multiple simultaneous users, digitizes a received analog RF signal and tunes to multiple desired frequencies of the received signal on a time division multiplexed basis. After filtering by a finite impulse response (FIR) filter that also operates in time division multiplexing for multiple service bands, the selected signals are digitally demodulated and signal processed, again on a time-shared basis. Different service bands are accommodated at the same time by separate FIR filters, each including a coefficient memory for its particular service band. The multiplexed frequency signal for each band is multiplied by the coefficients of its respective FIR filter memory in a common complex multiplier. The results are demultiplexed and directed to respective accumulators for decimation in accordance with the FIR coefficient characteristics.

Abstract: Apparatus and methods for establishing half-duplex communication between a first unit and a second unit over a telephone line. The first unit may transmit a first matching signal stream, the first matching signal stream including a first conditioning segment and a first unmodulated carrier signal having a first characteristic carrier frequency, the first characteristic carrier frequency representing a given transmission mode, the given transmission mode being in half-duplex. The second unit may analyze the first characteristic carrier frequency to recognize the given transmission mode.

Abstract: The disclosure relates to the transmission of data by packets, in a network, with a search for an optimum use of the allocated band of frequencies. The packets are all formed by a header followed by an information field. The headers are all sent out on the same carrier frequency and the radio resources allocated to an information field are limited to a parallelogram demarcated by two first parallels corresponding to two fixed frequencies external to the frequencies allocated to headers and by two second parallels that have the same frequency/time slope for all the packets and whose position in time is deduced from the observation of the header. Thus, with knowledge of the resources used by the packets that are being transmitted, a terminal may send out a new packet as closely as possible to the packets that are being transmitted, but without any risk of interference with these packets. Application to transmission by packets.

Abstract: A method and apparatus for separating and removing distortion from interfering co-channel signals and suppressing adjacent-channel interfering signals of the Gaussian Minimum-Shift Keyed (GMSK) or other MSK type with filtering structures that exploit the cyclostationarity of the received GMSK or other MSK signals in order to accommodate a greater number (or the same number, but with greater quality) of transmitted signals received by one or more antennas than can be accommodated by existing filters. The parameters in these filtering structures are adapted by either of two adaptation apparatus that exploit both the known training sequence that is transmitted in most wireless communications systems, and the constant modulus property exhibited by each of the transmitted GMSK or other MSK signals.

Abstract: The invention relates to the organization of phase references in a data transfer system based upon the multiplexing of orthogonal frequency components, when transmissions in the system are composed of relatively short symbol sequences. In accordance with the invention, in the first symbol (OS1) of the sequence differential phase-shift keying between elementary signals is carried out, based upon a phase reference (Ref) transmitted in one or several subfrequency bands (fc) and upon a phase shift chain propagated one subfrequency thereof at a time. In each subfrequency band in the subsequent symbols of the sequence phase-shift modulation refers to the elementary signal of the preceding symbol of the same subfrequency band. The invention may be applied with benefit to digital cellular network systems which employ the OFDM method.

Abstract: A synchronization network that provides frame timing that is particularly suited for a Eureka-147 system is disclosed. The synchronization network reduces the typical amount of computations required to provide for frame timing schemes and includes matched filtering operations that separate the waveforms of null and sine symbols contained in the multiple carriers of the Eureka-147 system. The matched filtering technique are accomplished before a fast Fourier transform operation and which accomplishments elimination of the need of an inverse fast Fourier transform operation normally performed by one of the receiver elements of the Eureka-147 system. This elimination is accomplished without degrading the performance of the Eureka-147 system.

Abstract: A digital communications network comprises a plurality of network hosts connected to communicate using an ATM network. Each network host uses policies (configured by the network administrator) to control an IP/ATM protocol layer. Based on these policies, the IP/ATM protocol layer classifies submitted IP packets and establishes and manages ATM connections having parameters appropriate for each class of traffic. By configuring the policies, the network administrator can tune the hosts to optimally use network resources. The resources of primary concern are available bandwidth and connection setup capacity. In the simplest case, the IP/ATM protocol layer classifies packets submitted from the IP network protocol as data traffic or control traffic based on packet size. Generally, large IP packets are classified as data traffic, while smaller IP packets are classified as control traffic. Data traffic is sent over the ATM network using ATM connections having relatively high bandwidths and relatively short time-outs.

Abstract: A wireless user terminal (10), such as a cellular telephone, is of a type that receives a forward digital control channel that is comprised of a plurality of continuously transmitted frames, comprised of time slots, which are logically organized into Superframes contained within Hyperframes. A method includes the steps of (a) receiving and storing a first SPACH slot from a first Hyperframe; (b) receiving and storing at least a F-BCCH slot from a second, next Hyperframe; (c) receiving a second SPACH slot from the second, next Hyperframe; (d) decoding the stored first SPACH slot and the second SPACH slot and calculating a CRC of each decoded SPACH slot using DVCC information contained within the received F-BCCH slot; and (e) comparing a state of a BCN flag in the first SPACH slot to the state of the BCN flag in the second SPACH slot and, if they are equal, declaring that the received and stored F-BCCH slot is valid.

Abstract: A method and apparatus of communicating information using Time Division Multiple Access and adaptive transmission and reception are disclosed. Signal bursts are transmitted from TDMA transmitters to a TDMA receiver wherein the transmitter codes the information and transmits coded information to the receiver using at least one of two timeslots of a plurality of timeslots in a repetitive TDMA frame period. Both of the two timeslots are received whether or not the transmitter has transmitted using one or two timeslots and the received signals are classified as intended and non-intended. Successively received signals classified as intended are then assembled into a block for decoding to reproduce the information.

Abstract: The method and apparatus of the present invention uses DSI with a TDMA/FDMA communication protocol. For each speech frame detected by a speech detector (110), a communication unit (CU) (108) sends (440) a speech detected indicator (SDI) (208) to a switching facility (SF) (138). In response, the SF (138) allocates an uplink reuse unit (260) which identifies a carrier frequency (301-360) and timeslot (190-193) which the CU (108) should use to transmit a traffic burst containing a compressed speech frame. The SF (138) allocates (506) the uplink reuse unit (260) from a pool of available uplink reuse units and, if necessary, allocates a downlink reuse unit (262) from a pool of available downlink reuse units. A message (220) describing the reuse units (260, 262) is transmitted (508) to the CU (108) which then transmits (450) and receives (480) traffic bursts during the allocated reuse units (260, 262).

Abstract: A terrestrial Rf telephone system provides a plurality of voice signal channels on a plurality of forward direction carrier frequencies, each carrier frequency having an associated predetermined bandwidth which is designed to accommodate one analog voice signal, and each carrier frequency containing a plurality of slots. The system includes a base station having a plurality of circuit paths for receiving a plurality of forward direction digitized voice signals; a plurality of compressors for compressing the voice signals; a processor for assigning each of the compressed voice signals onto a dynamically assigned frequency/slot; a plurality of channel controllers, each for sequentially combining the compressed digitized voice signals into a single transmit channel bit stream, with each compressed voice signal occupying a respective repetitive sequential time slot in the transmit channel bit stream; and a plurality of modulators for modulating the carrier frequencies.

Abstract: A method for automatically managing the communication channel resources between two nodes having neighboring nodes in a network of transceiver nodes, wherein each node communicates during specific time slots and uses multiple frequencies on a time division multiple access basis includes the steps of storing a table of possible communication frequencies and time slots between nodes; and announcing and transmitting during a specific time slot, a selected transmit frequency and slot from a first node to a second node and all neighboring nodes of the first node. The announced frequency and slot have certain constraints on reuse within two hops of the transmitting node to thereby establish contention free communication on that frequency and slot between the first and second nodes.

Abstract: A multichannel communication system has a transmitter for frequency-division-multiplexing and transmitting signals in a plurality of channels, and a receiver for selectively receiving the signal in one of the channels. The multichannel communication system prevents additional information from being interrupted in reception due to a channel change, for thereby reliably transmitting such additional information. The transmitter has a control information multiplexing unit for time-division-multiplexing main information in each of the channels with control information common to the channels at the same timing, and a transmitting unit for frequency-division-multiplexing and transmitting the main information in each of the channels which has been time-division-multiplexed with the control information by the control information multiplexing unit.

Abstract: A filter fast Fourier transmultiplexer divides a multi-channel communication signal into single channel communication signals through a cascade of filters and mixers. The output sample rate is maintained at the input sample rate and memory requirements and computations are substantially reduced.

Abstract: The hybrid medium access control MAC system is configurable to the type of communication required to support a desired application or service. The MAC system analyzes services requested from a settop terminal, or a network controller client, and determines the best MAC component for transmitting signals upstream based on the resources required by the service and the available network resources. A portion of the upstream channel spectrum is allocated to each of the MAC components: 1) POP; 2) assigned static TDMA; 3) assigned dynamic multi-rate TDMA; and 4) random slot reservation-dynamic slot allocation TDMA. Depending upon the communication requirements of the service desired, the configurable MAC system will select the MAC component best suited to support the service. A frequency agile transmitter is then tuned to the channel which has been preallocated for the selected MAC component(s).

Abstract: A system for the wireless transmission of multiple information signals utilizing digital time division circuits between a base station and a plurality of subscriber stations. The subscriber stations may be fixed or movable. The number of time division circuits is determined by the transmission quality of the signals. The base station is interconnected with an external information network, which may be analog and/or digital. The information signals are selected from the group consisting of voice, data, facsimile, video, computer and instrumentation signals. The modulation level of the signals and the power applied to the system are adjusted in accordance with signal error detection in the system. The system is provided with spatial diversity by using a plurality of antennas selectively spaced from each other to provide relatively high signal reception despite signal fading. The base station operates over a plurality of RF channel pairs.

Abstract: A frequency-division multiplexer for carrying an OFDM signal on a large number of closely-spaced carriers receives the digital data at an input (12), applies coding such as convolutional coding (14), time interleaves (16) the signals, and assembles them frame-by-frame in a matrix (18). The data are converted to parallel form by a shift register (18), frequency interleaved (24), differentially encoded (26), and quadrature-phase-modulated (28) on several hundred or more closely-spaced carriers. A first inverse Fast Fourier Transform (FFT) circuit (30) transforms this information from the frequency domain into the time domain. Instead of being transmitted directly, the resultant signals are then amplitude-limited (42) and applied to an FFT (44) to reconvert them into the frequency domain. The phases of the wanted signals are then re-set, and the amplitudes of the signals near the edges of the band are reduced, in correction circuits (46).

Abstract: An asymmetric network communication system for use in a client-server environment having independent forward and return channels operating at different speeds and/or under different protocols on the same or different communication media to provide efficient utilization of shared resources. A network manager, such as a hybrid access system, effects transmission of packetized data on a forward (downstream) channel from the host server to multiple client devices coupled with a shared downstream media at 10 or more megabits per second while simultaneously providing selectable multiple lower speeds of operation on shared or dedicated return (upstream) channels from the client devices to the host server depending on bandwidth availability, bandwidth demand, service level authorization, etc. for the return channel.