Abstract: Secure tunneled multicast transmission and reception through a network is provided. A join request may be received from a second tunnel endpoint, the join request indicating a multicast group to be joined. Group keys may be transmitted to the second tunnel endpoint, where the group keys are based at least on the multicast group. A packet received at the first tunnel endpoint may be cryptographically processed to generate an encapsulated payload. A header may be appended to the encapsulated payload to form an encapsulated packet, wherein the header includes information associated with the second tunnel endpoint. A tunnel may be established between the first tunnel endpoint and the second tunnel endpoint based on the appended header. The encapsulated packet may be transmitted through the tunnel to the second tunnel endpoint. The second tunnel endpoint may receive the encapsulated packet. Cryptographic processing of the encapsulated packet may reveal the packet having a second header.

Abstract: A method for detecting a communication relay attack involves the steps of counting a number of clock cycles occurring in a clock signal between transmission of two predetermined elements of data with a data transmission device, counting a number of clock cycles occurring in the clock signal between receipt of the two predefined elements of data and comparing the number of clock cycles counted by the data transmission device with the number of clock cycles counted by the data receiving device.

Abstract: A scrambling code generating apparatus of a downlink transmitter in a UMTS mobile communication system, which uses one primary scrambling code for separation of base stations and multiple secondary scrambling codes for channel separation. The apparatus includes a first m-sequence generator for generating a first m-sequence and a second m-sequence generator for generating a second m-sequence. A first summer adds the first and second m-sequences to generate the primary scrambling code. A plurality of first masking sections each shift the first m-sequence, and a plurality of second masking sections corresponding to the respective first masking sections each shifts the second m-sequence. A plurality of second summers each adds one of the first shifted m-sequences with the second m-sequence corresponding to the first m-sequence. The output of the second summers thus generates the multiple secondary scrambling codes.

Abstract: Invention presented here relates to Low Probability of Exploitation and Anti Jamming communication system offering high spectral efficiency. The object of the present invention is achieved by hopping in polarization domain and by employing an adaptive polarization-nulling algorithm (FIG. 18, H [2,2]) to detect and eliminate jamming signal. The use of signals which hops or spreads in polarization domain does not need wide frequency spectrum due to which, the said modulation when employed at the physical layer offers and extremely secure and survivable wireless communication at very high data rates.

Abstract: A method is described for implementing a trusted computing environment within a data processing system where the data processing system includes a single hardware trusted platform module (TPM). Multiple logical partitions are provided in the data processing system. A unique context is generated for each one of the logical partitions. When one of the logical partitions requires access to the hardware TPM, that partition's context is required to be stored in the hardware TPM. The hardware TPM includes a finite number of storage locations, called context slots, for storing contexts. Each context slot can store one partition's context. Each one of the partitions is associated with one of the limited number of context storage slots in the hardware TPM. At least one of the context slots is simultaneously associated with more than one of the logical partitions.

Abstract: An approach is provided for operating a radio network, wherein the operating frequency is varied systematically according to an enciphered sudden-frequency-change scheme and retained only during a hop. Several hops are combined to form a service interval, a service window being arranged at a variable position within the service interval. Given hops for different functionalities (late traffic entry, break-in, hailing, late network entry) of the radio network are specified in the service window.

Abstract: A spread spectrum method and apparatus for protecting and authenticating wirelessly transmitted digital information using numerous techniques. The apparatus may be a wireless code division multiple access (CDMA) communication system, a base station, a wireless transmit/receive unit (WTRU), a transmitter, a receiver and/or an integrated circuit (IC). The wireless CDMA communication system includes a transmitter which steganographically embeds digital information in a CDMA communication signal and wirelessly transmits the CDMA communication signal. The system further includes a receiver which receives the CDMA communication signal and extracts the steganographically embedded digital information from the received CDMA communication signal.

Abstract: A multi-band radio having seamless satellite communication capability is provided. The radio includes: a user interface for controlling operations of the radio; an encryption module; a LOS wireless transceiver for transmitting encrypted data at a frequency in the radio frequency spectrum; a BLOS wireless transceiver for transmitting encrypted data at a frequency in the microwave frequency spectrum; and a router for routing the encrypted data to at least one of the LOS transceiver and the BLOS transceiver.

Abstract: A scrambling code generating apparatus of a downlink transmitter in a UMTS mobile communication system, which uses one primary scrambling code for separation of base stations and multiple secondary scrambling codes for channel separation. The apparatus includes a first m-sequence generator for generating a first m-sequence and a second m-sequence generator for generating a second m-sequence. A first summer adds the first and second m-sequences to generate the primary scrambling code. A plurality of first masking sections each shift the first m-sequence, and a plurality of second masking sections corresponding to the respective first masking sections each shifts the second m-sequence. A plurality of second summers each adds one of the first shifted m-sequences with the second m-sequence corresponding to the first m-sequence. The output of the second summers thus generates the multiple secondary scrambling codes.

Abstract: A encoding/decoding method and device for a remote controller utilizing a baud rate to encrypt data for transmission. The encoding device includes an encoder encoding an identification code into an encrypted code; and an interpreter interpreting the un-encoded portion of the identification code and the encrypted code into a transmission signal. When the encrypted code is in a first base, the plain code corresponding to the encrypted code will be transmitted with a first baud rate; and when the encrypted code is in a second base, the plain code corresponding to the encrypted code will be transmitted with a second baud rate. The decoding device includes a receiver receiving the transmission signal; a interpreter connected to the receiver interpreting the transmission signal into a received signal; an encoder utilizing the same encoding algorithm as in the transmitter to generate a comparison code; and a processor comparing the received signal and the comparison code.

Abstract: A communication system that can satisfactorily communicate with a mobile station by a transmitter and receiver of a simple arrangement wherein a plurality of carriers having different frequencies are transmitted simultaneously and data is transmitted on the basis of a phase difference between the carriers. Also, the carriers are multiplied with a predetermined time waveform and transmitted, so that a reception side receives data by use of a time waveform narrower than the above time waveform.

Abstract: A variety of systems responsive to watermarked documents are detailed. In one, watermarking is employed to facilitate secure online transactions. In another, a system for exchanging data is provided. One system includes a user terminal and a central site. The user terminal includes a watermark reader, and a capture device to capture an image of a watermarked document. The central site includes a database of image hashes. The user terminal communicates with the central site. The watermark reader reads a watermark and computes a hash of a captured image, and passes the hash to the central site for comparison with the database of image hashes.

Abstract: A wireless communication system. The system comprises transmitter circuitry (BST1), the transmitter circuitry comprising encoder circuitry (50) for transmitting a plurality of frames (FR). Each of the plurality of frames comprises a primary synchronization code (PCS) and a secondary synchronization code (SSC). The encoder circuitry comprises of circuitry (501) for providing the primary synchronization code in response to a first sequence (32). The encoder circuitry further comprises circuitry (502) for providing the secondary synchronization code in response to a second sequence (54) and a third sequence (56). The second sequence is selected from a plurality of sequences. Each of the plurality of sequences is orthogonal with respect to all other sequences in the plurality of sequences. The third sequence comprises a subset of bits from the first sequence.

Abstract: Disclosed is a method and an apparatus for testing an optical fiber by using a biorthogonal codes and a Moore-Penrose inverse matrix. The method includes the steps of: (a) coding 2n optical pulses according to each codeword of the n-bit biorthogonal code matrix (2n*n matrix), injecting the coded optical pulses into an optical fiber, and measuring 2n optical signals generated when the coded optical pulses are reflected from the optical fiber; (b) decoding the 2n optical signals measured in step (a) by means of the Moore-Penrose inverse matrix (n*2n matrix) for the n-bit biorthogonal code matrix, thereby restoring n signals; (c) shifting the n signals along the time axis to remove timing differences among the n signals; and (d) performing an average operation for the time-shifted n signals and obtaining a final measured value.

Abstract: A chaotic communication system employs transmitting and receiving chaotic oscillating circuits. In an embodiment of the invention employing a Chua circuit as the basic chaotic circuit, the transmitter has a tank circuit portion and a Chua diode portion linked through a resistance. The capacitance of the tank circuit is varied by selectively switching in and out of the tank circuit an auxiliary capacitance isolated by an optoisolator. Switching of the optosiolator is controlled by an information signal to generate a perturbed oscillation in the transmitting circuit. A voltage is tapped from the Chua diode circuit and transmitted to carry the information from the information signal. A receiver in another embodiment applies the transmitted signal to both the tank circuit and Chua diode portions of the receiving circuit. The transmitted signal is applied through a resistor to the Chua diode portion as well as the tank circuit portion.

Abstract: A time domain communications system wherein a broadband of time-spaced signals, essentially monocycle-like signals, are derived from applying stepped-in-amplitude signals to a broadband antenna, in this case, a reverse bicone antenna. When received, the thus transmitted signals are multiplied by a D.C. replica of each transmitted signal, and thereafter, they are, successively, short time and long time integrated to achieve detection.

Abstract: A method for embedding a watermark signal that contains message data in a digital image sequence having two or more frames, includes the steps of: producing a set of two or more different carrier signals from a single secure key; assigning a carrier signal from the set of carrier signals to each frame in the sequence; and embedding a watermark signal in each frame using the corresponding assigned carrier signal.

Abstract: Ciphered information is transmitted over a first communication path in circuit mode between a core network and a terminal, passing through a first master controller, then over a second path between the core network and the terminal, passing through a second master controller. The second path is established in a procedure comprising the transmission of data from the first to the second master controller, a phase of simultaneous transmission of radio signals by the infrastructure on the first and second paths, then the suppression of the first path. The radio signals transmitted on the two paths during the phase of simultaneous transmission transport the same information, ciphered with offset sequence numbers, and the radio terminal switches over from the first to the second path while advancing the ciphering sequence number in such a way as to align it with the offset number used by the second controller.

Abstract: The present invention comprises a method of relating characteristics gleaned by monitoring application transaction flows (and the decomposition thereof) to produce performance metrics useful to characterize the efficiency and performance of web transactions used in a web-based application. These metrics can assist application designers and developers in reorganizing their application content, programs, and transports to provide improved service to their consumer. Events are generated and composed into predefined activities on a web transaction basis. The performance metric is then derived that entails a relationship between at least two different activities that gives insight into the performance characteristics of the web transaction. By using the derived performance metrics, designers and developers of web pages can judge the effects of changes to their application relative to efficiency and performance. Different applications can also be compared and contrasted using these metrics.

Abstract: One embodiment of the present invention is a method for receiving a secured transmission of information in an ADSL environment using a DMT modulation technique. The order of the frequency orthogonal subchannels used in the DMT technique is scrambled according to a permutation cipher. The key for this scrambling operation is scrambled with the subscriber's public key, and is encoded according to a CDMA technique for transmission through the ADSL channel approximately concurrently with the information. The encoded key and the DMT data subblocks are recovered from the secured transmission. The encoded key is decoded according to the CDMA technique to generate the decoded key. The decoded key is used to assign an order to the subblocks of data.

Abstract: Transponders present in an interrogation zone can be identified by an interrogator by it sending an RF interrogation signal into the interrogation zone, the RF interrogation signal containing a code string prompting the transponders to generate partial addresses. As soon as one transponder “sees” that the generated partial address agrees with part of its own address, it responds by sending its full address which can then be read by the interrogator. Immediately after having received a full address the interrogator sends a code string characterizing the address of the transponder having responded before so that this transponder is thereby addressable. The signal sent by the interrogator to the transponder with this code string also contains an instruction which prompts the transponder to assume the condition in which it no longer responds to receiving its address or partial address.

Abstract: The invention relates to a method and a generator for generating a short orthogonal spreading code in CDMA radio system. The method includes obtaining control data the length, the running number and the code class of the spreading code. A spreading code is formed such that the running number of the spreading code in the code class is first denoted by a binary code number of the same length as the code class. Thereafter, a modified code number is formed by reversing the code number. The following operations are repeated for each chip Of the spreading code: the running number of the chip is denoted by a binary chip number of the same length as the code class, and a binary sum is formed with an AND operation between the modified code number and the chip number, and one value is formed for the chip of the spreading code with an XOR operation between all the bits of the binary sum.

Abstract: One embodiment of the present invention is a method for providing security for a transmission of information in an ADSL environment using a DMT modulation technique. The order of the frequency orthogonal subchannels used in the DMT technique is scrambled according to a permutation cipher. The key for this scrambling operation is scrambled with the subscriber's public key, and is encoded according to a CDMA technique for transmission through the ADSL channel approximately concurrently with the information. The encoded key and the DMT data subblocks are recovered from the secured transmission. The encoded key is decoded according to the CDMA technique to generate the decoded key. The decoded key is used to assign an order to the subblocks of data.

Abstract: An N session distributed architecture provides a software solution to the major computational challenges faced with providing secure communication. A registration entity is identified as the session arbitrator through which N devices on a network dynamically participate in establishing, maintaining and destroying cryptographic sessions. Session keys are generated by one or more devices registered with the registration server. Multiparty key agreement is used to pass session keys to all parties involved in the encrypted session. All sessions appear to be local to the arbitration server, however individual session are maintained by several devices operating as a collective. Encrypted stream partitioning and computational resource allocation to decrypt the individual partitions in such way as to ensure system stability with increasing session demands is introduced in the architecture.

Abstract: A playback device generates a Pseudo-random noise (PN) code sequence repeatedly with a predetermined period in synchronism with a video sync signal. An anti-duplication control signal is spectrally spread using this generated PN code sequence, is superimposed on the video signal, and is output. A PN code sequence having the same timing and code pattern as the PN code sequence used in the playback device is similarly generated based on the video sync signal on the receiving side which receives the output video signal. Using this PN code sequence, reverse spectral spread is performed, the anti-duplication control signal superimposed on the video signal is extracted, and anti-duplication control is performed according to the extracted anti-duplication control signal.

Abstract: Watermark data is encoded in a digitized signal by forming a noise threshold spectrum which represents a maximum amount of imperceptible noise, spread-spectrum chipping the noise threshold spectrum with a relatively endless stream of pseudo-random bits to form a basis signal, dividing the basis signal into segments, and filtering the segments to smooth segment boundaries. The data encoded in the watermark signal is precoded to make the watermark data inversion robust and is convolutional encoded to further increase the likelihood that the watermark data will subsequently be retrievable notwithstanding lossy processing of the watermarked signal. To produce the endless pseudo-random bit stream, subsequent bits of the sequence are generated in a pseudo-random manner from previous bits of the sequence. The pseudo-random bits are appended to the stream of pseudo-random bits and, additionally, replace a number of bits of the state.

Abstract: The invention relates to a method of providing connection security for a connection between terminals in a wireless network. In the method data is transmitted from a first terminal (MS1) via nodes in the network to a second terminal (MS2). The method according to the invention is characterized by that it includes the steps of: routing the transmitted data via a mediator (MD), using the first security method for providing connection security at the security protocol layer between the first terminal (MS1) and the mediator (MD), using the second security method for providing connection security at the security protocol layer between the mediator (MD) and the second terminal (MS2), and performing the security method conversion at the security protocol layer at the mediator (MD).

Abstract: A frequency hopping communication system having a plurality of wireless mobile stations and at least one base station. Each wireless mobile station is operated to communicate according to a communication frame format generated by a base station. The system performing slow frequency hopping by keeping a frequency hopping interval within each frame. The hopping pattern of a frequency is designated at a field located at the tail of each communication frame by the base station.

Abstract: A spread-spectrum code division multiple access interference canceler for reducing interference in a direct sequence CDMA receiver having N chip-code channels. The interference canceler includes a plurality of correlators or matched filters, a plurality of spread-spectrum-processing circuits, subtracting circuits, and channel correlators or channel-matched filters. Using a plurality of chip-code signals, the plurality of correlators despreads the spread-spectrum CDMA signal as a plurality of despread signals, respectively. The plurality of spread-spectrum-processing circuits uses a timed version of the plurality of chip-code signals, for spread-spectrum processing the plurality of despread signals, respectively, with a chip-code-signal corresponding to a respective despread signal. For recovering a code channel using an i.sup.

Abstract: A time domain communications system wherein a broadband of time-spaced signals, essentially monocycle-like signals, are derived from applying stepped-in-amplitude signals to a broadband antenna, in this case, a reverse bicone antenna. When received, the thus transmitted signals are multiplied by a D.C. replica of each transmitted signal, and thereafter, they are, successively, short time and long time integrated to achieve detection.

Abstract: A method and apparatus for the selection of random values from a set of N non-sequential values includes software in ROM and RAM for information pool storage. Coupled to the ROM and RAM, a microprocessor sorts the values from smallest to largest, initializes local variables, processes a current value from a first value of the set, and compares the difference to a current information pool entry difference. A range increment is incremented if the difference equals the current information pool entry difference and a new information pool entry is created if the difference does not. The information pool is stored and random values are selected by generating a pseudo random number, constraining the pseudo random number between one and N, indexing into the information pool using the pseudo random number to create a pool entry index and generating the random value using a selected pool entry first value.

Abstract: Each transmission frame within a spread spectrum communications system relating to synchronization code transmission is divided into a plurality of slots. Each of the slots includes a primary (pilot) code c.sub.p and a secondary (combined) code c.sub.s/lci that includes information identifying or indicative of both a frame timing and a scrambling code for synchronization. This information concerning frame timing and scrambling code may be encoded in the combined code c.sub.s/lci itself, as well as in the modulation values of the sequences of plural combined codes within a frame. Alternatively, the information is encoded in the sequence of plural combined codes c.sub.s/lci transmitted in each frame, as well as in the modulated values of the sequences of plural combined codes within a frame. As yet another alternative, the information is encoded in the timing of the combined code c.sub.s/lci transmission within each slot of the frame relative to its associated primary code c.sub.p.

Abstract: A phased array spread spectrum system for maximizing signal strength of a spread-spectrum signal with multipath through the use of receiving means, delaying means, combining means, despreading means, generating means, storing means and comparing means. The receiving means receives a plurality of spread-spectrum signals and a plurality of phased versions of the plurality of spread-spectrum signals. The delaying means delays the received plurality of spread-spectrum signals with respect to the plurality of phased versions of the plurality of spread-spectrum signals by a plurality of delays. The combining means combines the delayed spread-spectrum signals and the plurality of phased versions of the plurality of spread-spectrum signals as a plurality of combined signals. The despreading means despreads the plurality of combined signals as a plurality of despread signals. The generating means generates a plurality of magnitude values from the plurality of despread signals.

Abstract: A covert communication apparatus exploits chaotic dynamics in the multi-dimensional phase space with a continuous number of states and wide internal spectral bandwidth. The information modulates a chaotically generated signal, and the modulated chaotic signal is shaped for compatibility with the specific constraints demanded by the communication channel. In an analog embodiment, the chaotic signal spectrum is band limited to be compatible with the bandwidth requirements of the transmission link, and in a digital embodiment the word length and baud rate of the transmitted digital data are selected for similar transmission link compatibility. After transmission over the communication link, the received signal is applied to a receiver chaotic signal generator substantially identical to the transmitter chaotic signal generator and the chaotic signal is recovered. This chaotic signal is used to demodulate the received signal for recovery of the information.

Abstract: A watermark is embedded into audio/video/image/multimedia data using spread spectrum methodology. The watermark is extracted from watermarked data without the use of an original or unwatermarked version of the data by using spatial or temporal local averaging of the frequency coefficients of the watermarked data.

Abstract: An apparatus for communicating variable rate data over a communication channel. A modulator that receive frames of user data each comprised of data symbols. The modulator repeats the data symbols within each frame to maintain a constant data rate. A transmitter receiver the modulator data and scales the modulated symbol data based upon the amount of symbol repetition in the frame.

Abstract: The transmitting and receiving apparatus and method for full code correlation operation under encryption for the Satellite Positioning System (SATPS) are disclosed. The apparatus includes a central station designed to receive SATPS satellites encoded information using a high gain antenna and a delayed correlation receiver. The central station extracts the encrypted satellite information and transmits it to the delayed correlation receiver. The delayed correlation receiver receives the encrypted satellite information using the standard SATPS antenna and performs the full correlation with the encrypted information received from the central station without requiring the secret encryption keys.

Abstract: A base station communicates with a plurality of mobile stations over a cellular network. In one embodiment, the base station includes a receiver having a receiver synthesizer input, where the receiver is configured to receive inbound information from the mobile station on a first predetermined frequency. The receiver further has two programmable frequency sources that are configured to alternately supply a receiver synthesizer input signal to the receiver. The base station also includes a transmitter having a transmitter synthesizer input, where the transmitter is configured to transmit outbound information to the mobile station on a second predetermined frequency. The transmitter further has two programmable frequency sources that are configured to alternately supply a transmitter synthesizer input signal to the transmitter.

Abstract: Individual information signals encoded with a common block error-correction code are assigned a unique scrambling mask, or signature sequence, taken from a set of scrambling masks having selected correlation properties. The set of scrambling masks is selected such that the correlation between the modulo-2 sum of two masks with any codeword in the block code is a constant magnitude, independent of the mask set and the individual masks being compared. In one embodiment, when any two masks are summed using modulo-2 arithmetic, the Walsh transformation of that sum results in a maximally flat Walsh spectrum. For cellular radio telephone systems using subtractive CDMA demodulation techniques, a two-tier ciphering system ensures security at the cellular system level by using a pseudorandomly generated code key to select one of the scrambling masks common to all of the mobile stations in a particular cell.

Abstract: A multichannel television access control system is disclosed wherein processing of the broadband signal is performed by gated coherent RF injection on a plurality of channels, thereby effecting selective descrambling of an arbitrary subset of channels in a channel group. The system provides for a closed loop injection signal phasor control so as to maintain substantially constant relationship between the television signals and the injected signals. The combined signals are supplied to subscribers enabling the use of their cable ready equipment.

Abstract: Individual information signals encoded with a common block error-correction code are assigned a unique scrambling mask, or signature sequence, taken from a set of scrambling masks having selected correlation properties. The set of scrambling masks is selected such that the correlation between the modulo-2 sum of two masks with any codeword in the block code is a constant magnitude, independent of the mask set and the individual masks being compared. In one embodiment, when any two masks are summed using modulo-2 arithmetic, the Walsh transformation of that sum results in a maximally flat Walsh spectrum. For cellular radio telephone systems using subtractive CDMA demodulation techniques, a two-tier ciphering system ensures security at the cellular system level by using a pseudorandomly generated code key to select one of the scrambling masks common to all of the mobile stations in a particular cell.

Abstract: A spread-spectrum code division multiple access interference canceler for reducing interference in a direct sequence CDMA receiver having N chip-code channels. The interference canceler includes a plurality of correlators or matched filters, a plurality of spread-spectrum-processing circuits, subtracting circuits, and channel correlators or channel-matched filters. Using a plurality of chip-code signals, the plurality of correlators despreads the spread-spectrum CDMA signal as a plurality of despread signals, respectively. The plurality of spread-spectrum-processing circuits uses a timed version of the plurality of chip-code signals, for spread-spectrum processing the plurality of despread signals, respectively, with a chip-code-signal corresponding to a respective despread signal. For recovering a code channel using an i.sup.

Abstract: A system and method for communicating information signals using spread spectrum communication techniques. PN sequences are constructed that provide orthogonality between the users so that mutual interference will be reduced, allowing higher capacity and better link performance. With orthogonal PN codes, the cross-correlation is zero over a predetermined time interval, resulting in no interference between the orthogonal codes, provided only that the code time frames are time aligned with each other. In an exemplary embodiment, signals are communicated between a cell-site and mobile units using direct sequence spread spectrum communication signals. In the cell-to-mobile link, pilot, sync, paging and voice channels are defined. Information communicated on the cell-to-mobile link channels are, in general, encoded, interleaved, bi-phase shift key (BPSK) modulated with orthogonal covering of each BPSK symbol along with quadrature phase shift key (QPSK) spreading of the covered symbols.

Abstract: A method, apparatus and system is described for distributing accurate time-of-day information from an existing telecommunications infrastructure without modifying the existing infrastructure. In particular, the system comprises a base station device which continually receives extremely accurate time-of-day information from, by way of example and not by limitation, a GPS (Global Positioning Satellite) system, a local atomic dock, or a wired or wireless time standard. The base station periodically places time-of-day information into standard paging packets for transmission over a standard paging network. The paging packets are sent over telephone lines to the paging terminal for transmission whenever a time slot for transmission becomes available. The base station device records the actual time of transmission of the paging packet containing the time of day information and prepares the next time-of-day packet by placing the exact transmission time of the previous time-of-day packet sent.

Abstract: The present invention provides for a locking mechanism for use in a door and the like. A remote handheld controller transmits coded signals to an electronic door lock. A sensor/receiver receives the signals and provides the signal to a processor which compares the coded signals against a predetermined stored signal. If the received coded signal matches the predetermined signal, then the processor generates control signals to actuate an electromechanical device, which acts solely along or about the locking axis, to enable or disable the locking latch. The user is then able to turn the door handle in a normal manner. The coded signals are comprised of two separate signals which are transmitted in segments interleaved with one another. The first signal includes an entrance code, while the second signal provides information concerning the frequency over which the next segments will be transmitted. The processor uses the second signal information to tune the receiver.

Abstract: The dual mode communication network comprises a first communication system having a frame structure and a first traffic channel protocol and a second communication system having the frame structure and a second traffic channel protocol. In the network, only one of the first and second traffic channel protocols supports forward error correction coding.

Abstract: In this patent, we present MultiCode Direct Sequence Spread Spectrum (MC-DSSS) which is a modulation scheme that assigns up to N DSSS codes to an individual user where N is the number of chips per DSSS code. When viewed as DSSS, MC-DSSS requires up to N correlators (or equivalently up to N Matched Filters) at the receiver with a complexity of the order of N2 operations. In addition, a non ideal communication channel can cause InterCode Interference (ICI), i.e., interference between the N DSSS codes. In this patent, we introduce new DSSS codes, which we refer to as the “MC” codes. Such codes allow the information in a MC-DSSS signal to be decoded in a sequence of low complexity parallel operations which reduce the ICI. In addition to low complexity decoding and reduced ICI.

Abstract: A time domain communications system wherein a broadband of time-spaced signals, essentially monocycle-like signals, are derived from applying stepped-in-amplitude signals to a broadband antenna, in this case, a reverse bicone antenna. When received, the thus transmitted signals are multiplied by a D.C. replica of each transmitted signal, and thereafter, they are, successively, short time and long time integrated to achieve detection.

Abstract: In this patent, we present MultiCode Direct Sequence Spread Spectrum (MC-DSSS) which is a modulation scheme that assigns up to N DSSS codes to an individual user where N is the number of chips per DSSS code. When viewed as DSSS, MC-DSSS requires up to N correlators (or equivalently up to N Matched Filters) at the receiver with a complexity of the order of N.sup.2 operations. In addition, a non ideal communication channel can cause InterCode Interference (ICI), i.e., interference between the N DSSS codes. In this patent, we introduce new DSSS codes, which we refer to as the "MC" codes. Such codes allow the information in a MC-DSSS signal to be decoded in a sequence of low complexity parallel operations which reduce the ICI. In addition to low complexity decoding and reduced ICI. MC-DSSS using the MC codes has the following advantages: (1) it does not require the stringent synchronization DSSS requires, (2) it does not require the stringent carrier recovery DSSS requires and (3) it is spectrally efficient.

Abstract: A radiolocation system for multipath environments, such as for tracking objects in a semiconductor fabrication facility (FIGS. 1a-1b), includes an array of receivers (20) distributed within the tracking area, coupled to a system processor (40) over a LAN. A TAG transmitter (30) located with each object transmits, at selected intervals, spread spectrum TAG transmissions including at least a unique TAG ID. In a high resolution embodiment, object location is accomplished by time-of-arrival (TOA) differentiation, with each receiver (FIG. 2b) including a TOA trigger circuit (64) for triggering on arrival of a TAG transmission, and a time base latching circuit (65) for latching the TOA count from an 800 MHz time base counter. In a low resolution embodiment, each receiver of the array is assigned a specific location-area, and receives TAG transmissions almost exclusively from TAGs located in that area, thereby eliminating the need for any time-of-arrival circuitry.