Abstract: Methods and apparatus for solving problems caused by backoff procedures like that specified in the BLUETOOTH Link Layer Specification, by introducing selected randomizations of communication channels used for communication by scanning devices.

Abstract: A system including a control module and a correlation module. The control module receives signals, including subcarriers having frequencies in a frequency band, via a plurality of antennas, and divides the frequency band into sub-bands each including a plurality of the subcarriers. The correlation module generates sets of correlation values by correlating symbols in the sub-bands with a plurality of preamble sequences. A set of correlation values is generated for one of the plurality of antennas and is generated based on the preamble sequences. The control module generates sums by adding selected correlation values from the sets. The selected correlation values in a sum are generated respectively for the plurality of antennas and are generated based on one of the preamble sequences. The control module detects a preamble sequence in the signals by determining whether a largest one of the sums is greater than or equal to a predetermined threshold.

Abstract: A method, an apparatus, and a computer program that includes forming frequency hopping position of the sounding reference signal is based on a hopping pattern. The hopping pattern of the sounding reference signal is configured to utilize a tree assignment for a frequency allocation of the sounding reference signal and to support at least one frequency band branch per layer. The hopping pattern of the sounding reference signal is also configured to provide consecutive sounding reference signals on widely separated frequency allocations.

Abstract: The present invention includes a method of determining a phase estimate for an input signal having pilot symbols. The method includes receiving a plurality of pilot symbols, and then multiplying two or more pilot symbol slots by corresponding correlator coefficients to correct a phase estimate of the input signal.

Abstract: A method of processing first and second corresponding signals having a delay therebetween. The method includes introducing a plurality of different delays between the first and second signals, successive delay amounts differing from each other by less than the interval between chip boundaries, and for each introduced delay, summing samples of the second signal which are obtained at the times of, at least, chip boundaries between bits of the first signal which have the same state, to obtain a value; thereby to obtain a representation of how the value varies according to the introduced delay, which representation contains a level change associated with an introduced delay which bears a predetermined relationship to the delay between the first and second signals.

Abstract: A wireless receiver for receiving signals from a satellite positioning system, and receiving signals from a communications system uses a common path in the receiver, and derives position information (60, 230) from the received signals by correlation (50, 210, 220) with a code. In a first mode the deriving is carried out from the received signals excluding selected signals received in time slots used for communications signals. A second mode includes such signals. This enables control of the trade off between accuracy and the latency of the positioning processor to improve the performance over a range of conditions. The mode input can be changed dynamically according to signal strength, or according to the needs of an application.

Abstract: Methods and apparatuses are provided to enable User Equipments (UEs) to apply Orthogonal Covering Codes (OCC) to the transmission of Reference Signals (RS) generated from Constant Amplitude Zero Auto-Correlation (CAZAC) sequences, to enable hopping of these sequences in a communication system in conjunction with enabling the application of OCC, and to differentiate the application of sequence hopping between transmissions in data channels and transmissions in control channels.

Abstract: A system and method for redundant transmission is provided. In one embodiment, an input signal S is encoded as a list of fragments. Each fragment includes an index value and a projection value. The index points to an entry in a dictionary of signal elements. A repetition factor is assigned to each fragment based on its importance. After a fragment is added, a reconstructed signal is generated by decoding the list of fragments. Encoding terminates once the reconstructed signal is sufficiently close to the original signal S.

Abstract: An apparatus is disclosed comprising collocated primary receiver (PR) and a time synchronized receiver (TSR), with a Low Noise Amplifier (LNA) configured by a LNA gain control signal to create a shared amplified signal sent to the PR and the TSR for them to concurrently receive packets. The TSR is configured to generate a timed signal strength prediction signal based on the shared amplified signal and the LNA gain control signal. The primary receiver is configured to generate the LNA gain control signal based, at least in part, on the timed signal strength prediction signal. The PR may include a spread spectrum receiver, and the TSR may include a frequency hopping receiver.

Abstract: The present invention relates to reception and processing of spread spectrum signals to produce position/time related data. A proposed receiver includes a radio signal processing unit, which is at least partly implemented in software running on a microprocessor. The processor is also adapted to effect at least one separate software-controlled function. The receiver is adapted to operate the radio signal processing unit on at least two processing intensity levels each with different processing times. Thereby, when the radio signal processing unit operates on a low processing intensity level, a first amount of processing capacity is available for the at least one separate software-controlled function; and when the radio processing unit operates on a high processing intensity level, a second amount of processing capacity is available for the at least one separate software-controlled function. When the processor's over-all processing capacity is constant, the second amount is smaller than the first amount.

Abstract: In one embodiment, a device in a channel hopping communication network independently maintains a slot counter, and computes a channel identification (ID) based on a function having inputs of i) a unique feature of the device, ii) a current slot of the slot counter, and iii) a set of possible channel IDs. Accordingly, the device configures its radio to receive on the computed channel ID for the respective current slot. In another embodiment, the device may determine, for a neighbor device, a current neighbor slot and unique neighbor feature, and correspondingly computes a neighbor channel ID based on the function using the unique neighbor feature, the current neighbor slot, and the set of possible channel IDs. As such, the device configures its radio to transmit on the computed neighbor channel ID for the respective current neighbor slot.

Abstract: In one exemplary embodiment of the invention, a device includes: a first frequency search engine configured to receive input values and determine a frequency of a signal to be within a first frequency band; a second delay component configured to store at least a portion of the plurality of input values; and a second frequency search engine configured to determine the frequency of the signal to be within a second band that is a subset of the first band. The first frequency search engine includes: a shift register configured to store bits of the input values; a combining circuit configured to combine bits of the plurality of input values; a first delay component configured to serially store a plurality of accumulator values; and a feedback circuit configured to add a function of the first delay component output to a next accumulator value to obtain a modified next accumulator value.

Abstract: A low-cost GPS/GNSS receiver receives a satellite signal at an RF frequency (fRF). The GPS/GNSS receiver includes a front end section for receiving the satellite signal and generating a digital complex signal having a first bandwidth, the received satellite signal being converted into a complex signal before digitizing, a signal capturing section for searching for and acquiring the satellite signal, the signal capturing section including a capture memory, a baseband processor for tracking the acquired satellite signal, and a signal splitter coupled to the front end section. The signal splitter splits the digital complex signal into two bandwidths, by generating a narrowband digital complex signal having a second bandwidth substantially smaller than the first bandwidth. The signal splitter provides the narrowband digital signal to the capture memory and the wider first bandwidth digital complex signal to the baseband processor.

Abstract: A system for implementing an orthogonal frequency division multiplexing scheme and providing an improved range extension. The system includes a transmitter for transmitting data to a receiver. The transmitter includes a symbol mapper for generating a symbol for each of a plurality of subcarriers and a spreading module for spreading out the symbol on each of the plurality of subcarriers by using a direct sequence spread spectrum. The symbol on each of the plurality of subcarriers is spread by multiplying the symbol by predefined length sequences. The receiver includes a de-spreader module for de-spreading the symbols on each of the plurality of subcarriers. The de-spreader module includes a simply correlator receiver for obtaining maximum detection. The correlator produces an output sequence of a same length as an input sequence and the de-spreader module uses a point of maximum correlation on the output sequence to obtain a recovered symbol.

Abstract: A correlation apparatus and method for frequency synchronization are provided. A frequency synchronization method of a receiver in a broadband wireless access communication system includes acquiring a highest correlation value by conducting a differential correlation of a variable interval between a received signal and a reference signal and performing a frequency synchronization according to the highest correlation value.

Abstract: Systems (100) and methods (700) for processing a data signal in a communications system. The methods involve generating a first chaotic sequence at a transmitter (102). The methods also involve performing first basis function algorithms using the first chaotic sequence to generate first statistically orthogonal chaotic sequences. At least one sequence is selected from the first statistically orthogonal chaotic sequences for combining with a first data signal. The selected sequence is combined with a second data signal to obtain a modulated chaotic communication signal. The modulated chaotic communication signal is transmitted to a receiver (104). At the receiver, the received modulated chaotic communication signal is processed to obtain data therefrom. Notably, the signal processing generally involves performing a deterministic process (e.g., a Hidden Markov Model deterministic process).

Abstract: A low complexity RACH preamble detector is described herein. The RACH preamble detection algorithm uses the peak detection of the time domain correlation function through frequency domain processing. The frequency domain processing considers the reference signals generated directly from frequency domain CAZAC sequence or time domain CAZAC sequence with DFT conversion. A low-complexity poly-phase LPF along with down sampling is implemented before the FFT to reduce the required length of the long FFT operation N-folded.

Abstract: A synchronization method in a Ultra Wideband (UWB) receiver includes receiving a signal through a multipath channel, and synchronizing with a first multipath component of the received signal by computing a correlation value between the received signal and a template signal of the receiver in a predetermined search range. Since multipath components received at the receiver after the first multipath component of the received signal have lower power than that of the first multipath component, the synchronization with the first multipath component of the received signal may improve the performance in processes after the synchronization process.

Abstract: A multipath searcher and method includes a programmable decimation filter configured to adjust a sample rate of a received pilot signal. A plurality of correlators is configured to compare the received pilot signal to a reference code in a first mode and in a second mode. The first mode includes a low resolution search of a search window performed such that the plurality of correlators encompass an entire search window concurrently and the plurality of correlators receives a delayed reference code delayed to correspond with a portion of the search window in which a corresponding correlator performs correlation to identify peaks in the received pilot signal. The second mode includes a high resolution search of a refined search window only at or near identified peaks discovered in the first mode. The high resolution search is focused at the peak location by adjusting delays in the plurality of correlators.

Abstract: A correlation apparatus for tracking a satellite signal includes a shifter, a multiplexer and an accumulator. The shifter generates generating a Prompt signal, a plurality of Early signals and a plurality of Late signals. The multiplexer outputs at least one of the plurality of Early signals and at least one of the plurality of Late signals. The accumulator acquires a correlation signal to tracking the satellite signal.

Abstract: A method for synchronization of transmitted and received signals in frequency hopping communications systems. A synchronization unit is arranged for synchronization of transmitted and received signals in frequency hopping communication systems and a frequency hopping communication system including a synchronization unit.

Abstract: System and method for operating a wireless narrowband receiver. A signal may be received on a channel of the wireless narrowband receiver. At least a portion of the signal may be received from a first wireless narrowband transmitter. The wireless narrowband receiver may implement an adaptive frequency hopping algorithm. It may be determined if interference is present on the channel and one or more errors are detected in receiving the signal. In response to determining that interference is present on the channel and one or more errors are detected in receiving the signal, received signal strength of one or more neighboring frequencies of the channel may be measured, and the resulting measurements may be stored in a memory. The measurements may be used to determine interference sources interference on the channel.

Abstract: A code phase error estimating method includes calculating correlation for I and Q components of a reception signal, judging code phase based on the result of the correlation calculation; calculating a ratio of first difference to a second difference, where the first difference is a first correlation value minus a third correlation value and the second difference is a second correlation value minus the third correlation value, the first correlation value being a correlation value at the code phase, the second correlation value being a correlation value at a phase shifted from the code phase by X chip (0<X<1), and the third correlation value being a correlation value at a phase shifted from the code phase by Y chip (1<Y); and estimating the code phase error when the reception signal is a multipath signal.

Abstract: The present invention includes a method of determining a phase estimate for an input signal having pilot symbols. The method includes receiving a plurality of pilot symbols, and then multiplying two or more pilot symbol slots by corresponding correlator coefficients to correct a phase estimate of the input signal.

Abstract: Systems, apparatuses and methods for managing message communications in systems employing frequency hopping. One method according to the invention involves transmitting a message via a frequency of a frequency hopping sequence, and determining when the same frequency will reoccur in the frequency hopping sequence. Relevant portions of the device enter a sleep mode, and the device emerges from the sleep mode when the frequency at which the message was transmitted reoccurs in the frequency hopping sequence. The device monitors for a response to the message via the frequency at which the message was transmitted when the frequency reoccurs in the frequency hopping sequence.

Abstract: A device performs demodulation of control signals from multiple radio terminals, based on the correlations in the frequency domain between a predetermined code and the orthogonalized control signals and reference signals of the multiple radio terminals obtained by cyclic shifts of the predetermined code. The device includes: a demultiplexer which demultiplexes a reference signal component and a control signal component based on a correlation profile; a path detector which detects a path location or path locations for each radio terminal based on the power values of the reference signal components; extractor which extracts the correlation values of the reference signal components and the correlation values of the control signal components, respectively; and RAKE combiner which combines the extracted values.

Abstract: An OFDM transmitter and receiver realizing high-speed cell search and having a reducible circuit scale. An OFDM transmitter includes an SCH inserting section for constructing a frame where a synchronization sequence in a predetermined position from the head of a first sub-frame is arranged and a synchronization sequence composed of the symbols of the former synchronization sequence and the symbols whose I, Q components are interchanged is arranged in a predetermined position from the head of a second sub-frame adjacent in the time-axis direction to the former sub-frame, an IFFT section, a P-SCH conversion section, and an RF transmitting section for transmitting this frame. Thus, the receiving end of the frame can locate the position of either synchronization sequence and determine the frame timing from that position, thereby increasing the speed of the cell search.

Abstract: A preamble code usable in Orthogonal Frequency Division Multiple Access (OFDMA) for the physical layer (PHY), selected for improved PAPR in a 1024, 512 or 128 FFT OFDMA mode. Tables 2 to 7 detail code sequences having improved PAPR performance. The disclosed codes may be used in cellular wireless.

Abstract: A control unit sends a plurality of request messages to the I/O units. The I/O units send a plurality of response messages to the control unit. The request messages and response messages are sent using radio-frequency signals. The I/O units expect to receive a request message within defined first time intervals, and the control unit expects to receive at least one response message within defined second time intervals. The control unit and the I/O units maintain a selected transmission frequency for as long as the request messages and response messages are received within the defined time intervals. The control unit and the I/O units change the transmission frequencies according to a defined pattern if no expected message is received within the defined time intervals.

Abstract: Techniques for detecting and demodulating data transmissions in wireless communication systems are presented. In one aspect, a decision-directed detector detects for data transmissions in a received signal by utilizing received data symbols as well as received pilot symbols. The decision-directed detector may be designed to perform differential detection in the frequency domain or coherent detection in the time domain, and may be used with multi-carrier modulation (e.g., OFDM). In another aspect, an adaptive threshold is used to perform detection of received data transmissions. A threshold may be determined for each data transmission hypothesized to have been received. The threshold may be computed, for example, based on the signal plus noise energy of the hypothesized data transmission.

Abstract: A communication system, such as a wireless CDMA system, detects markers with fewer errors by having field units transmit the markers at different power levels (e.g., 9 dB for one marker and 11 dB for another marker). The difference in power levels of the markers allows the base station to identify the request markers using alternative criteria with a low probability of error, where the alternative criteria may include comparing the markers to respective energy level thresholds, monitoring occupancy of time slots, occupancy of mutually exclusive code channels, or combinations thereof. For example, in one particular embodiment, a request marker, which is generally a high priority marker, is transmitted with higher power, which improves the probability of detection and reduces the probability of false detection of the request marker.

Abstract: A spreading signal acquisition and tracking method and apparatus is proposed. In accordance with the present invention, coherent integrations are performed by segments and stored for a non-coherent integration. A better freedom of the non-coherent interval selection is provided. The window of the non-coherent integration is sequentially and gradually shifted to achieve better update rate to its detection circuit and to improve searching and tracking for a spreading signal. By using the present invention, rapid signal acquisition can be achieved even when intensity of the spreading signal is very weak, or even when deeper signal blocking or jamming occurs.

Abstract: One embodiment of the invention provides a method of creating a set of secondary spreading codes for use in a satellite navigation system comprising a constellation of satellites. Each satellite in the constellation employs a tiered spreading code comprising at least a primary code and a secondary code. Each satellite in the constellation is allocated a different secondary spreading code from the set of secondary spreading codes. The method involves generating an initial set of bit patterns, where each bit pattern represents a potential secondary spreading code. The method further involves performing an optimization process on bit patterns within the initial set of bit patterns. As a result of the optimization, at least some of the bit patterns in the initial set are modified or replaced, to create a final set of bit patterns for use as the set of secondary spreading codes.

Abstract: Systems and techniques are disclosed relating to communications. The systems and techniques involve separating a plurality of subscriber stations into first and second groups, a different first code from a plurality of orthogonal codes to each of the subscriber stations in the first group, assigning each of the subscriber stations in the first group either its allocated first code or a first sub-code derived from its allocated first code, to support a dedicated channel, and assigning a second sub-code derived from one of the first codes to support a communications channel to one of the subscriber stations in the second group. A second code may be used to support a dedicated channel to the second subscriber station.

Abstract: Signal instances are detected from within a long period of a received radiofrequency RF signal envelope, grouped according to signal level, and periodicities are determined among the grouped signal instances. Periodicity of one of the groups is matched to a known periodicity, and a frequency domain is estimated at a time instance derived from the matched periodicity. If an expected frequency pattern is found that occupies the derived time instance in the estimated frequency domain, then a receiver is synchronized to a candidate signal that lies within the frequency pattern. Then content of the candidate signal is decoded and that content is used to access a cognitive radio system (e.g., register to the system, start the normal operation in the network such as spectrum detection and/or transmission in a traffic channel, etc.).

Abstract: A method of processing positioning signal constituted by a superposition of individual signals generated by a plurality of emitters, in particular satellite emitters, comprising:—a first step of coarse acquisition of said individual signals, comprising correlation of the received positioning signal with locally generated replicas of said individual signals;—a step of identifying spurious correlation peaks induced by interferences; and—a step of estimating the code delays and the carrier frequency shifts of the acquired individual signals which are not affected by said interferences. According to preferred embodiments of the invention, the method can also comprise:—a refining step of determining more accurate estimates of said code delays and carrier frequency shifts; and—a step of interference cancellation. The method of the invention is particularly suitable to indoor positioning applications.

Abstract: Power switches of circuits at respective stages of a low noise amplifier, demodulators, low-pass filers, variable gain amplifiers, and analog-to-digital converters are controlled to be off by an operation control unit in a non-reception period of an impulse signal. An increase in power consumption due to the adoption of an active filter or a variable gain amplifier is compensated for by a reduction in power consumption through intermittent operations of the circuits at the respective stages according to on and off control of the power switches.

Abstract: A transmitter/receiver system for high data transfer in a wireless communication system includes a physical layer processor that comprises an FEC coder, a demultiplexer and a plurality of modem processors. The FEC coder applies error correction codes to the high data rate signal. Thereafter, the demultiplexer distributes portions of the coded high data rate signal to the modem processors. Each modem processor processes its respective portion of the coded signal for transmission in an independent channel.

Abstract: The quality of signals during SDMA is raised. In an uplink, a signal processing unit receives signals respectively from a plurality of terminal apparatuses which have been multiple-accessed by division of time. It derives receiving channel characteristics corresponding to the plurality of terminal apparatuses, respectively, for each time slot. In a downlink, the signal processing unit derives transmitting channel characteristics from the receiving channel characteristics derived and, based on the transmitting channel characteristics derived, it transmits signals respectively to the plurality of terminal apparatuses to which SDMA has been performed.

Abstract: A method of transmitting a spread spectrum signal in a single communication session between a transmitter and a receiver, stores a series of N unique waveform designs and a hopping sequence in a transmitter memory. A signal is transmitted to a receiver according to the hopping sequence using the plurality of N unique waveform designs. Preferably, each waveform design is characterized by a unique composite spreading code that is formed by at least some of a plurality of constituent code segments. Alternatively or additionally, the waveform designs may differ by any one or more of code length, symbol or chip timing or phase, frame or burst structure, chip offset, modulation, error control coding, encryption scheme, or scrambling code. A transmitter and receiver are also disclosed, as is the concept of appending chips between symbols to expand the universe of unique spreading codes without incurring an increase in processing gain.

Abstract: Certain aspects of a method and system for achieving space and time diversity gain are disclosed. Aspects of one method may include modifying a generalization code of at least one pilot channel, to measure signal strengths for each of a plurality of received multipath signals. A portion of the plurality of received multipath signals may be combined based on the measured signal strengths. The signal strengths of the plurality of received multipath signals may be measured on a primary pilot channel by assigning its generalization code to zero. The signal strengths of the plurality of received multipath signals on a secondary pilot channel may measured by assigning its generalization code to a non-zero value.

Abstract: A system for processing a received signal having at least one code applied thereto, the received signal having a frequency, the system comprising: first correlator circuitry arranged to correlate the received signal with a first code to provide an output; second correlator circuitry arranged to correlate the received signal with a second code to provide an output, wherein the first code and the second code are different; and processor for processing together the outputs of the first and second correlator circuitry to cancel the frequency.

Abstract: A communication device of the present invention includes channel compensations, an adaptive processor, a MAC and a controller. The channel compensations weight each of signals received by a plurality of antennas based on an SN ratio of the received signals so as to control the antennas to operate as combining diversity systems. The adaptive processor weights each of the signals received by the plurality of antennas so as to suppress the interference signal and to control the antennas to operate as adaptive array antennas. The MAC detects frequency hopping information of the received signals. The controller changes between the operation of the combining diversity systems and the operation of the adaptive array antennas, based on the frequency hopping information.

Abstract: Each base station transmits a TDM pilot 1 having multiple instances of a pilot-1 sequence generated with a PN1 sequence and a TDM pilot 2 having at least one instance of a pilot-2 sequence generated with a PN2 sequence. Each base station is assigned a specific PN2 sequence that uniquely identifies that base station. A terminal uses TDM pilot 1 to detect for the presence of a signal and uses TDM pilot 2 to identify base stations and obtain accurate timing. For signal detection, the terminal performs delayed correlation on received samples and determines whether a signal is present. If a signal is detected, the terminal performs direct correlation on the received samples with PN1 sequences for K1 different time offsets and identifies K2 strongest TDM pilot 1 instances. For time synchronization, the terminal performs direct correlation on the received samples with PN2 sequences to detect for TDM pilot 2.

Abstract: A method of generating a spread-spectrum clock signal includes delaying a high frequency clock signal to provide a plurality of delayed high frequency clock signals selected among to provide a spread-spectrum clock signal for a synchronous system.

Abstract: A receiver in an impulse wireless communication. The receiver (300) includes a pulse-pair correlator (304) that receives a signal (316) and divides it into two signals for paths. One of the signals is input to signal multiplier (312) while another signal is delayed by a delay unit (310). The signal multiplier (312) multiplies the received signal (316) by a delayed signal (318). An integrator (314) integrates an output signal (322) over a designated period of time. An adding module (306) sums an output signal (324) from the integrator (314). An acquiring module (308) compares an summing-up output (326) from the adding module (306) with a predetermined threshold value to detect the existence of a transmitting-standard preamble.

Abstract: Improvements are disclosed for in-band signaling, i.e., transmission of data in a voice channel of a digital wireless network during a voice call session. A family of narrow-band signaling methods is disclosed to successfully pass data-carrying signals through the low-bit rate modes of the EVRC-B vocoder commonly used in CDMA wireless channels. Some embodiments generate a tapered signaling waveform in tandem with another waveform using FSK-modulation. These features can be used in cell phones or other wireless communication devices, including automotive applications.

Abstract: Methods and systems of a receiver selecting a subset of plurality of frequency hopping bands for synchronization of the receiver are disclosed. One method includes the receiver determining a receive signal quality metric for each band of the plurality of frequency hopping bands, and selecting at least one synchronization band as a subset of the plurality of frequency hopping bands for synchronization based on the receive signal quality metric of each of the plurality of frequency hopping bands.

Abstract: A method of transmitting a spread spectrum signal in a single communication session between a transmitter and a receiver, stores a series of N unique waveform designs and a hopping sequence in a transmitter memory. A signal is transmitted to a receiver according to the hopping sequence using the plurality of N unique waveform designs. Preferably, each waveform design is characterized by a unique composite spreading code that is formed by at least some of a plurality of constituent code segments. Alternatively or additionally, the waveform designs may differ by any one or more of code length, symbol or chip timing or phase, frame or burst structure, chip offset, modulation, error control coding, encryption scheme, or scrambling code. A transmitter and receiver are also disclosed, as is the concept of appending chips between symbols to expand the universe of unique spreading codes without incurring an increase in processing gain.

Abstract: An automatic gain control method and system for use in signal processing of OFDM symbols at a receiver. Two stages of coarse and fine automatic gain control are implemented that adjust different gains in an analog RF processing stage of the receiver. Gain of a low noise amplifier and a mixer are adjusted during a first and coarse automatic gain control stage based on feedback from a digital baseband stage. During a subsequent fine gain control period, the gain of a programmable gain amplifier is adjusted separately for each frequency band used by the OFDM symbols based on a histogram bin that counts the number of output samples of an analog to digital converter whose magnitude falls within certain ranges. Coarse and fine gains are updated after each OFDM symbol.