A new ultra-wide bandwidth communication system using both a time-hopping (TH) sequence and a direct spreading sequence, called direct-sequence impulse radio (DS-IR), has recently been proposed. An exact analysis to evaluate the bit error rate (BER) performance of this new scheme in multi-user interference (MUI) is provided. On the basis of this new analysis, ultra-wideband communication systems employing TH, direct-sequence and the newly proposed DS-IR schemes operating in MUI are accurately compared in terms of the BER. Our results indicate that DS-IR outperforms the TH binary phase-shift keying (BPSK) system. However, its performance is poorer than the performance of the conventional full-duty direct sequence BPSK system. Compared with the low-duty direct sequence BPSK system, DS-IR achieves a better error rate performance for medium and large signal-to-noise power-ratio values.

Pulse design is examined for multiple access ultrawideband communication systems with consideration of the transmitter pulse-shaping and the receiver filter at the same time, subject to a transmitter power constraint. It is shown that an appropriate sinc pulse not only conforms to required spectral emission constraints, but also optimizes the signal-to-noise-plus interference ratio of the ultra-wideband system when corrupted by multiple access interference. Compared with previously proposed pulse shapes, the sinc pulse proposed here achieves better error rate performance in multiple access environments without adding any implementation complexity. The design of ideal ultrawideband pulses is clarified in terms of properties of the spectral emission mask.

Pulse design is examined for multiple access ultra- wideband communication systems with consideration of the transmitter pulse-shaping and the receiver filter at the same time, subject to a transmitter power constraint. It is shown that an appropriate sine pulse not only conforms to required spectral emission constraints, but also optimizes the signal-to-noise-plus- interference ratio of the ultra-wideband system when corrupted by multiple access interference. Compared with previously proposed pulse shapes, the sine pulse proposed here achieves better error rate performance in multiple access environments without adding any implementation complexity. The design of ideal ultra- wideband pulses is clarified in terms of properties of the spectral emission mask.

A precise analysis is derived for calculating the bit error probability of a direct-sequence ultra-wideband system accounting for the multiuser interference on additive white Gaussian noise (non-frequency selective) channels. The exact solution is validated by simulation and used to determine the accuracy of a recently published approximation based on a simplified receiver decision statistic, as well as to assess the inaccuracy of the Gaussian approximation. It is established that the Gaussian approximation may only be accurate for an impractically large number of simultaneous users.

A new ultra-wide bandwidth communication system using both a time-hopping sequence and a direct spreading sequence, called direct-sequence impulse radio, has recently been proposed. The performance of this new scheme in multi-user interference is investigated. A precise expression for calculating the bit error probability of direct-sequence impulse radio is derived. Our precise analysis indicates that the Gaussian approximation substantially overestimates the performance at large values of signal-to-noise power ratio. Ultra-wideband communication systems employing time-hopping, direct-sequence and the newly proposed direct-sequence impulse radio schemes operating in multi-user interference are accurately compared in terms of the bit error rate. Our results indicate that direct-sequence impulse radio outperforms the time-hopping binary phase-shift keying system. However, its performance is poorer than the performance of conventional direct sequence binary phase-shift keying systems

An analysis is derived for calculating the bit-error probability of an ultra-wideband (UWB) communication system operating with binary phase-shift keying and quaternary phase-shift keying narrowband interference in additive white Gaussian noise. The analytical expressions are valid when phase transitions of the interfering symbols can be ignored. The accuracy of the Gaussian approximation is assessed, and several modulation schemes proposed for UWB communication are evaluated in terms of capability of interference suppression.

A novel paradigm is proposed to design time-limited pulse shapes for ultra-wideband communication systems. Pulses can be designed using the new paradigm that not only conform to spectral emission constraints, but also achieve good bit error rate performance in multiple access interference environments. Compared with previously proposed pulses, the novel pulses provide the same multiple access performance as the Gaussian monocycles yet have advantages over them in terms of power spectrum and spectral emission constraints. Our pulse design paradigm provides a flexible and effective method for designing suitable pulses for ultra-wideband communication applications that comply with frequency emission constraints

The all-Rake and selective-Rake receiver structures are examined for different transmission scenarios, including multiple access interference and intersymbol interference environments. The results show that the all-Rake receiver does not necessarily offer the best performance when operating in intersymbol interference environments. Some candidate modulation schemes proposed for ultra-wideband communications are assessed and compared using a measurements-based fading model. Although some analytical and semi-analytical methods using the Gaussian approximation predict the same bit error rate estimates for several modulation schemes, our results show that the actual performances of these modulation schemes are different

An exact analysis is derived for precisely calculating the bit error probability of an ultra-wideband communication system operating in IEEE 802.11a narrowband interference. The analytical expressions are used to assess the accuracy of the Gaussian approximation, a widely adopted method for estimating the interference. The Gaussian approximation is shown to be inaccurate for predicting the bit error rate for some system parameters. The performance degradation of the ultra-wideband communication system in the presence of interference from orthogonal frequency division multiplexing signals is accurately evaluated. Several modulation schemes proposed for ultra-wideband communications are compared in terms of capability for OFDM interference suppression. The effects of system parameters on the bit error rate performance are also addressed through numerical examples.

An exact analysis is derived for precisely calculating the bit error probability of time-hopping and direct-sequence ultra-wideband systems with multi-user interference in an additive white Gaussian noise environment. The analytical expressions are validated by simulation and used to assess the accuracy of the Gaussian approximation proposed for estimating the performance of ultra-wideband communication systems. The Gaussian approximation is shown to be inaccurate for predicting the bit error rate for medium and large signal-to-noise ratio values. The performances of time-hopping and direct-sequence modulation schemes are accurately compared for different numbers of users and frame widths. It is shown that direct-sequence binary phase-shift keying outperforms time-hopping binary phase-shift keying for medium and large values of signal-to-noise ratio, which contradicts some previous results obtained using a Gaussian approximation.

A novel algorithm is proposed to design time-limited pulse shapes for ultra-wideband communication systems. The new algorithm can be used to design pulses that not only conform to spectral emission constraints, but also achieve good bit error rate performance in multiple access interference environments. Compared with previously proposed pulses, the novel pulses provide the same multiple access performance as Gaussian monocycles, yet have advantages over them in terms of power spectrum and spectral emission constraints. Our pulse design algorithm provides a flexible and effective method for designing suitable pulses for ultra-wideband communication applications that comply with frequency emission constraints.

A characteristic function method is proposed for precisely calculating the bit error probability of time-hopping ultra-wideband systems with multiple access interference. The analytical expressions are validated by simulation and used to assess the accuracy of the Gaussian approximation. The sensitivity of the performance of the modulation schemes to the system parameters is also addressed through numerical examples. The performances of time-hopping pulse position modulation and binary phase-shift keying modulation schemes are accurately compared based on the new analytical results.

A characteristic function method is proposed for precisely calculating the bit-error probability of time-hopping (TH) ultra-wideband (UWB) systems with multiple-access interference in an additive white Gaussian noise environment. The analytical expressions are validated by simulation and used to assess the accuracy of the Gaussian approximation. The Gaussian approximation is shown to be inaccurate for predicting bit-error rates (BERs) for medium and large signal-to-noise ratio (SNR) values. The performances of TH pulse position modulation (PPM) and binary phase-shift keying (BPSK) modulation schemes are accurately compared in terms of the BER. It is shown that the BPSK system outperforms the binary PPM system for all values of SNR. The sensitivity of the performance of the modulation schemes to the system parameters is also addressed through numerical examples.