Abstract: The present invention is a system, apparatus, and method for current MB-OFDM systems to design a time-domain sync sequence regarding DAA that (1) minimizes change to the current sync sequence, and (2) maintains the robustness of synchronization. Two tone-notching embodiments are provided for sync sequence design in the preamble when OFDM systems require detect-and-avoid (DAA) ability. The receiver needn't be aware of the change of sync sequence at the transmitter and can still use the original sync sequence. The design can be used in both DAA and non-DAA transmission modes.

Abstract: The system, apparatus and method of the present invention provides a single carrier block transmission with guard interval as a means of communications over multi-path channels that enables frequency domain equalization, and therefore, has many of the advantages of OFDM, but does not have some of the drawbacks such as high PAPR and the need for high resolution ADCs. While the use of guard intervals in single carrier communications enables low complexity detection of the signal, it reduces bandwidth efficiency. The present invention improves the bandwidth efficiency by adjusting the length of the guard interval adaptively. Also, by allowing both time-domain and frequency domain equalizations, besides improving bandwidth efficiency, the inventions allows for great flexibility in receiver design.

Abstract: A synchronization sequence (preamble) that is known to the receiver forms as an integral part of packet-based digital communication systems. The first operation in such digital communication systems is the detection of the beginning of a valid signal (packet). The present invention provides a system, apparatus, and method for a scheme to robustly detect the preamble. The scheme of the present invention has the following advantages: it is robust to noise and interference, it provides the frequency error directly without any additional computation, it provides information that is necessary to position the FFT window for an OFDM based modulation, it provides a real part of the peak that can be used for frame synchronization, and finally, it provides the peak for burst detection purposes.

Abstract: The present invention provides a system (300-400), apparatus (300-400), and method for an energy-based antenna selection technique in which the antenna that observes the largest SNR averaged over all carriers per sub-band (405) is selected for space-time coded MB-OFDM systems. Due to the frequency-selective nature of the system, different sub-band may have different channel gaining effect from the multi-path channels. We can perform energy-based antenna selection per sub-band, and the simulation results show that the proposed technique works not only for MB-OFDM UWB channels with shadowing, but also for the same channel without shadowing.

Abstract: A method and apparatus for transmitting and receiving data via guard tones are described. The information bits are coded by convolutional encoder (101) and some of the punctured bits from punctured (102) are selected with bit selector (105) and subject as the punctured data to interleaving by an interleaver (106-103 for the punctured data-). The OFDM process that follows (104, 107, 108) maps the interleaved selected punctured bits to guard tones and the interleved punctured data to data sub-carriers.

Abstract: A method and an arrangement for uni- or bidirectional wireless communication of signals or data especially in a reflective environment like a MR imaging system, between at least one first transmitter and/or receiver unit (501, 601, 701; T/R1) and at least one second transmitter and/or receiver unit (801; T/R2) is disclosed. The reliability and availability of the communication link especially in a highly reflective environment is improved especially by using spread spectrum technology and ultra wide band carrier frequencies.

Abstract: A plurality of MAC/PHY stacks is adapted to support wireless devices. A superframe structure includes a preamble and a superframe initialization header.

Abstract: In a wireless communication network (200) comprising a base station (210) and a plurality of remote terminals (220), the plurality of remote terminals (220) are divided into a plurality of clusters (230) for communication with the base station (210), and each of the remote terminals (220) is assigned to a cluster (230) based on at least one characteristic, measured by one or more of the remote terminals (220), of one or more external signals transmitted by one or more external terrestrial transmitters (250) not associated with the communication network (200).

Abstract: A method (200) and system (300) for detecting a received signal, such as a UWB signal, select a first band (210) and search (230) for an autocorrelation peak in the signal in the first band. The autocorrelation peak is compared to a threshold (250), and it is determined that a signal is detected when the autocorrelation peak exceeds the threshold. In response to detecting the signal, the system (300) and method (200) select a second band (260), search (265) for an autocorrelation peak in the signal in the second band, and determine a coarse frequency error (275) in the signal from the autocorrelation peak in the second band. The coarse frequency error in the signal is corrected and a frame synchronization sequence of the signal is detected to complete the synchronization.

Abstract: A mostly-digital ultra-wideband (UWB) receiver that includes an adaptive combiner (125) having a matched filter with adaptive filter weights selected to maximize the output signal-to-noise (SNR) ratio and be insensitive to noise, channel and timing errors as the adaptive combiner is not dependent on the shape of the transmitted waveform in an adaptive filter-weight scheme. The receiver includes an UWB input filter 105 for filtering analog UWB RF input pulses; at least one parallel sub-sampling analog-to-digital converter (ADC) (120) for converting the filtered UWB RF analog pulses output from the UWB filter (105) into sub-sampled digital signals. An adaptive combiner (125) sums the sub-sampled digital waveforms output by the parallel ADC (120); and a polyphase clock generator (122) that provides the parallel ADC (120) with clock control pulses so that the sub-sampling ADC (120) only sub-samples and converts the filtered UWB RF analog wave only where a threshold of an expected energy of each pulse exists.

Abstract: In a transmitter, a standard stream of encoded multi-media data and uniform error correction data is transmitted through a first channel. The uniform error correction data provides substantially the same error correction for all portions of the encoded multimedia data. Simultaneously, additional unequal error correction data is generated for critical portions of the standard stream and not for other portions of the standard stream, and the additional error correct data is transmitted through a second channel. In a receiver, the additional error correct data is used to error correct just the critical portions of the standard stream, and then the uniform error correction data is used to error correct all the portions of the encoded multimedia data of the standard stream.

Abstract: A method and system for efficiently utilizing frequency spectrum resources is disclosed. The method comprises the steps of determining at least one spectrum opportunity (510), wherein the opportunity is identified by a frequency range and a time duration, determining a set of altered transmission characteristics (515, 517) to allow transmission of a desired signal in the identified frequency range, wherein the altered transmission characteristics avoid interference with signals expected in the frequency range, and transmitting said desired signal using the altered transmission characteristics when the transmission occurs during said time duration. In one aspect of the system, the step of determining at least one opportunity comprises the steps of receiving signals in known frequency ranges, and determining the characteristics of the received signals.

Abstract: A method for conveying, a receiver for receiving and a signal that contains a differential phase modulated multi-band high-speed data stream are provided. A preferred embodiment is directed to a multi-band UWB signal where each band spans about 500 MHz to 1 GHz. Within each such band, a flexible modulation scheme of the present invention is employed that comprises two-pulse duplets having a difference set to ?/2 or 90E. This modulation scheme allows adaptation of the data rate to the sub-band channel conditions. Within each band, time, amplitude and phase modulations are employed. In addition, a pseudorandom frequency sequence is employed to provide sufficient reduction of multi-user interference.

Abstract: An apparatus and method is disclosed for reducing error propagation in a decision feedback equalizer by constraining the values of feedback filter tap coefficients in a feedback filter of the decision feedback equalizer. The feedback filter tap coefficients that are constrained are calculated using a constraint cost function and a related constraint function. The constraint condition of the present invention reduces error propagation in a decision feedback equalizer by preventing error from circulating in a feedback loop of a feedback filter within the decision feedback equalizer.

Abstract: A system and method is provided for generating backward compatible robust ATSC 8-VSB bit streams for transmission by a digital transmitter. A backward compatible robust digital TV modulation technique is employed where a multiplexed stream of bits is encoded such that the constellation is similar to a standard 8-VSB constellation.

Abstract: This disclosure describes a flexible digital transmission system that improves upon the ATSC A/53 HDTV signal transmission standard. The system includes a digital television signal transmitter for generating a first Advanced Television Systems Committee (ATSC) standard 8-VSB bit stream and, for generating an encoded new bit stream capable of transmitting high priority information bits, wherein symbols of the new bit stream are capable of being transmitted according to a transmission mode selected from group comprising: a 2-VSB mode, a 4-VSB mode, and a hierarchical-VSB (H-VSB) transmission mode. Each respective 2-VSB, 4-VSB, and H-VSB mode is characterized as having symbols mapped according to possible symbol values from an alphabet comprising respectively, {?7, ?5, 5, 7}, {7, 3, ?3, ?7}, and {7, 5, 3, ?3, ?5, ?7}. The standard 8-VSB bit stream and new bit stream may be simultaneously transmitted over a terrestrial channel according to a broadcaster defined bit-rate ratio.

Abstract: The present invention provides a mechanism for alleviating a latency problem of one of the proposals for a potential IEEE 802.15.3a standard. The invention places band extension information into the frame sync sequence, as per the evolving standard, but places channel estimation information together with that of the 3-band channel estimation information using the actual TF code (909). The PLCP header (308) is transmitted using the actual TF code (909) and interleaver.

Abstract: A system and method for transmission and receipt of multi-band communication according to their time slot sequence includes at a transmitting end: an encoder for encoding data according to a time slot position (s1, s2, s3, s4) for each frequency band; an RF modulator for modulating encoded data over a predetermined plurality of frequency bands (f4, f3, f2, f1) selected from a plurality of frequency bands (f1, fn). The predetermined plurality of frequency bands are independent of each other and an order of transmission of the predetermined plurality of frequency bands being irrelevant, unlike the dependency in spectral keying. The present invention frees up the order of the frequency bands being transmitted, so that they can be used for channelization, security or other purposes and requires less complicated circuitry at the receiver end.

Abstract: A transmission system includes a first forward error correction unit, a robust processor unit, a trellis encoder unit, a second forward error correction unit, and a transmitter device. The first forward error correction unit encodes packets belonging to robust and normal bit streams. The robust processor unit receives the encoded robust packets and processes the robust packets to generate the robust bit stream. The trellis encoder unit produces a stream of trellis encoded data bits corresponding to bits of the normal and robust bit streams by mapping encoded data bits of the robust packets into symbols according to one or more symbol mapping schemes. The second forward error correction unit reads in only packets of the robust bit stream and enables generation of parity bytes only for the robust packets. The transmitter device transmits the robust bit stream over a communications channel to a receiver device.

Abstract: A packet formatter for use in a television receiver capable of receiving a dual bitstream signal comprising a standard stream compatible with the Advanced Television Systems Committee (ATSC) standard and a robust stream. The packet formatter comprises: 1) a first processing block capable of receiving the dual bitstream signal and removing therefrom header bits and parity bits associated with the robust stream to thereby produce a first output signal; and 2) a second processing block capable of receiving the first output signal and removing therefrom duplicate bits associated with the robust stream to thereby produce a second output signal that is output from a data path output of the packet formatter.