Showing papers on "Pulse-position modulation published in 2003"
11 May 2003
TL;DR: A new pulse shape is presented that satisfies the FCC spectral mask and it is shown that UWB can be a good candidate for reliably transmitting 100 Mbps over distances at about 10 meters.
Abstract: UWB systems based on impulse radio have the potential to provide very high data rates over short distances. In this paper, a new pulse shape is presented that satisfies the FCC spectral mask. Using this pulse, the link budget is calculated to quantify the relationship between data rate and distance. It is shown that UWB can be a good candidate for reliably transmitting 100 Mbps over distances at about 10 meters.
399 citations
TL;DR: This letter presents a new method for the evaluation of the bit error probability of a time hopping binary pulse position ultra-wideband modulation scheme, in the presence of multiuser interference, and a comparison with the Gaussian approximation is presented.
Abstract: This letter presents a new method for the evaluation of the bit error probability of a time hopping binary pulse position ultra-wideband modulation scheme, in the presence of multiuser interference. The technique permits to predict the system performance with high accuracy and reasonable complexity. A perfect agreement with simulation results is shown, and a comparison with the Gaussian approximation is presented.
201 citations
TL;DR: This paper addresses the space-time code design for Rayleigh-fading channels using continuous phase modulation (CPM) and identifies several sufficient conditions for full rank.
Abstract: This paper addresses the space-time code design for Rayleigh-fading channels using continuous phase modulation (CPM). General code construction is desirable due to the nonlinearity and inherent memory in CPM signals which make hand design or computer search computationally impractical. Several sufficient conditions for full rank are identified for CPM signaling schemes and for linear representations of CPM. Simulation results verify the resulting performance.
119 citations
TL;DR: The basic principles and characteristics of MSM techniques in optical wireless communications are presented and some block codes that convert information bits to be transmitted to the symbol amplitudes of subcarriers are used to increase the minimum value of the MS electrical waveform.
Abstract: This article overviews multiple-subcarrier modulation techniques in optical wireless communications. The basic principles and characteristics of MSM techniques in optical wireless communications are presented. MSM optical wireless systems are explained where some block codes that convert information bits to be transmitted to the symbol amplitudes of subcarriers are used to increase the minimum value of the MS electrical waveform. MSM optical communications systems using subcarrier signal point sequences (SSPS) that can improve the power efficiency of MSM systems are also explained. The performance of MSM optical communications systems is presented in the intensity modulation with direct detection (IM/DD) channel without dispersion and in atmospheric optical communications where the effects of scintillation exist.
116 citations
22 Apr 2003
TL;DR: In this article, the authors study the spectrum shaping of a UWB signal in accordance with the FCC regulations and IEEE 802.15.3a recommendations and show that the conventional UWB system with pulse-position modulation and time-hopping multiple access gives rise to spectral lines that violate the regulations.
Abstract: This paper studies how to design the spectrum of a UWB signal in accordance with the FCC regulations and IEEE 802.15.3a recommendations. We show that the "conventional" UWB system with pulse-position modulation and time-hopping multiple access gives rise to spectral lines that violate the regulations. The impact of different modulation and multiple access schemes on the spectrum shaping is derived from the power spectral density of a non-linear and memoryless modulation. Detailed theoretical and simulation results stress the difficulties raised by the use of dithered pulse trains. We thus propose several solutions to achieve compliance with the FCC spectral masks.
116 citations
Patent•
29 Dec 2003
TL;DR: In this paper, an ultra-wideband pulse modulation apparatus, system and method is provided. But this method is not suitable for the use in wireless and wired communication networks such as CATV networks.
Abstract: An ultra-wideband pulse modulation apparatus, system and method is provided. The pulse modulation method increases the available bandwidth in an ultra-wideband, or impulse radio communications system. One embodiment of the present invention comprises a pulsed modulation system and method that employs a set of different pulse transmission, or emission rates to represent different groups of binary digits. The modulation and pulse transmission method of the present invention enables the simultaneous coexistence of the ultra-wideband pulses with conventional carrier-wave signals. The present invention may be used in wireless and wired communication networks such as CATV networks.
108 citations
TL;DR: An ultra-wideband system with a hybrid pulse amplitude and position modulation (PAPM) scheme over indoor lognormal fading channels can provide a higher throughput than the binary pulse amplitude or pulse position modulation scheme.
Abstract: In this paper, the error performance of an ultra-wideband (UWB) system with a hybrid pulse amplitude and position modulation (PAPM) scheme over indoor lognormal fading channels is analyzed. In the PAPM UWB system, input data is modulated onto both the pulse amplitudes and pulse positions. The receiver employs a RAKE to combine energy contained in the resolvable multipath components. Derivation of closed-form error rate expressions of the system in lognormal fading channels is based on approximating a sum of independent lognormal random variables (RV) as another lognormal RV using the Wilkinson method. Given the same delay spread of the channel, the proposed PAPM scheme can provide a higher throughput than the binary pulse amplitude or pulse position modulation scheme.
96 citations
TL;DR: A new method is proposed for precisely calculating the bit error probability of a time-hopping binary pulse position modulation ultra-wideband system with multiple access interference.
Abstract: A new method is proposed for precisely calculating the bit error probability of a time-hopping binary pulse position modulation ultra-wideband system with multiple access interference. The analytical expression is validated by simulation and used to assess the inaccuracy of the Gaussian approximation.
95 citations
Book•
31 Jan 2003
TL;DR: Coded Modulation Systems is an introduction to the subject of coded modulation in digital communication designed for classroom use and for anyone wanting to learn the ideas behind this modern kind of coding.
Abstract: Coded Modulation Systems is an introduction to the subject of coded modulation in digital communication. It is designed for classroom use and for anyone wanting to learn the ideas behind this modern kind of coding. Coded modulation is signal encoding that takes into account the nature of the channel over which it is used. Traditional error correcting codes work with bits and add redundant bits in order to correct transmission errors. In coded modulation, continuous time signals and their phases and amplitudes play the major role. The coding can be seen as a patterning of these quantities. The object is still to correct errors, but more fundamentally, it is to conserve signal energy and bandwidth at a given error performance. The book divides coded modulation into three major parts. Trellis coded modulation (TCM) schemes encode the points of QAM constellations; lattice coding and set-partition techniques play major roles here. Continuous-phase modulation (CPM) codes encode the signal phase, and create constant envelope RF signals. The partial-response signaling (PRS) field includes intersymbol interference problems, signals generated by real convolution, and signals created by lowpass filtering. In addition to these topics, the book covers coding techniques of several kinds for fading channels, spread spectrum and repeat-request systems. The history of the subject is fully traced back to the formative work of Shannon in 1949. Full explanation of the basics and complete homework problems make the book ideal for self-study or classroom use.
93 citations
TL;DR: The firing scheme described in this work is inspired to a modulation scheme used in chaotic communications, called chaotic pulse position modulation (CPPM), which helps ultrasonic devices to discriminate its own echo.
Abstract: Ultrasonic devices are widely used in robotics as exteroceptive sensors for ranging measurements. Robotic applications often involve a large number of sonars operating concurrently, giving rise to the phenomenon of crosstalk. In this work, the problem of improving performance of ultrasonic devices in the presence of crosstalk and noise is addressed. In order for each device to discriminate its own echo, chaos is exploited to create unique firing sequences. In particular, the firing scheme described in this work is inspired to a modulation scheme used in chaotic communications, called chaotic pulse position modulation (CPPM). The evaluation of the time of flight is performed by a detection filter. The experimental setup consists of a Polaroid 600 electrostatic transducer driven by a continuous CPPM modulator. Experimental results confirm the suitability of the approach.
93 citations
TL;DR: In this paper, the bit error rate of the proposed system using PPM with considering the effects of the scintillation, avalanche photodiode noise, thermal noise, and multi-user interference was analyzed.
Abstract: We propose atmospheric optical code-division multiple-access (CDMA) systems. We analyze the bit-error rate of the proposed system using pulse-position modulation (PPM) with considering the effects of the scintillation, avalanche photodiode noise, thermal noise, and multi-user interference. We show that the atmospheric optical CDMA systems can realize high-speed communications when the logarithm variance of the scintillation is small. When /spl sigma//sub s//sup 2/ is large, we need to use forward-error correction codes.
07 Sep 2003
TL;DR: Novel prolate spheroidal wave functions are proposed as pulse shapes for use in impulse radio (ultra-wideband) communications and they are shown to have a constant pulse width regardless of the pulse order.
Abstract: In this paper novel prolate spheroidal wave functions are proposed as pulse shapes for use in impulse radio (ultra-wideband) communications These classes of functions yields orthogonal pulses and have a constant pulse width regardless of the pulse order This is an important property since it eliminates inter-symbol interference An M-ary communications system is considered that employs these pulses, and the generation of these pulses using the eigenfunction form of a self-adjoint operator is proposed It is also shown that these pulses are suitable for use in pulse position modulation (PPM) ultra wideband (UWB) communication systems
TL;DR: Differential phase-shift keying of optical pulses has virtually no pulse-pattern effect and is robust to cross-gain modulation in saturated semiconductor optical amplifiers (SOAs) that leads to crosstalk penalty for DWDM input signals.
Abstract: Conventional ON-OFF keyed modulation format is susceptible to cross-gain modulation in saturated semiconductor optical amplifiers (SOAs) that leads to crosstalk penalty for dense wavelength-division-multiplexing (DWDM) input signals. Differential phase-shift keying of optical pulses has virtually no pulse-pattern effect and is robust to cross-gain modulation. We report experimental results that confirm reduction of crosstalk penalty in SOA with differential phase-shift-keyed DWDM input signals in comparison with ON-OFF keyed signals operating at 12.5 Gb/s with 25-GHz channel spacing.
11 May 2003
TL;DR: A random coding bound is derived on the achievable information rates of ultra-wideband systems using a m-ary pulse position modulation with non-coherent receivers in multipath fading environments and the influence of system parameters is highlighted.
Abstract: In this work we investigate the achievable rates of ultra-wideband (UWB) systems using a m-ary pulse position modulation (PPM) with non-coherent receivers in multipath fading environments. We derive a random coding bound on the achievable information rates and highlight the influence of system parameters (bandwidth, delay spread). We also investigate the effect of the use of hard decisions prior to channel decoding and characterize its impact on system performance.
16 Nov 2003
TL;DR: An approximate characteristic function for the multiple access interference and the corresponding probability of error of the system is presented and the analytical results are compared with simulations and with the common Gaussian approximation.
Abstract: We investigate the performance of a time hopped-binary pulse position modulation system in the presence of multi-user interference. Since the exact characteristic function (as well as the pdf) for the multiple access interference is not known, and the Gaussian approximation (especially in presence of a small number of users) has been shown to be very poor, a new, non-Gaussian, approach is proposed. We first present an approximate characteristic function for the multiple access interference and the corresponding probability of error of the system; we then compare the analytical results with simulations and with the common Gaussian approximation.
13 Oct 2003
Abstract: In this paper, we propose direct sequence (DS) code division multiple access (CDMA) for ultra-wide bandwidth (UWB) impulse radio communications. The main design issues are outlined and performance is estimated in additive white Gaussian noise (AWGN). The performance of DS/CDMA is compared with that of time hopping (TH) using pulse position modulation (PPM). Both uncoded and convolutionally coded transmissions are considered.
TL;DR: The DSSS solution for IR wireless transmission demonstrates that a transmission waveform can be designed to remove the key channel impairments in a wireless IR system without having to resort to complex signal Processing techniques.
Abstract: Multipath dispersion and fluorescent light interference are two major problems in indoor wireless infrared communications systems. Multipath dispersion introduces intersymbol interference at data rates above 10 Mb/s, while fluorescent light induces severe narrowband interference to baseband modulation schemes commonly used such as OOK and PPM. This article reviews the research into the application of direct sequence spread spectrum techniques to ameliorate these key channel impairments without having to resort to complex signal Processing techniques. The inherent properties of a spreading sequence are exploited in order to combat the ISI and narrowband interference. In addition, to reducing the impact of these impairments, the DSSS modulation schemes have strived to be bandwidth-efficient and simple to implement. Three main DSSS waveform techniques have been developed and investigated. These are sequence inverse keying, complementary sequence inverse keying, and M-ary biorthogonal keying (MBOK). The operations of the three systems are explained; their performances were evaluated through simulations and experiments for a number of system parameters, including spreading sequence type and length. By comparison with OOK, our results show that SIK, CSIK, and MBOK are effective against multipath dispersion and fluorescent light interference because the penalties incurred on the DSSS schemes are between 0-7 dB, while the penalty on OOK in the same environment is more than 17 dB. The DSSS solution for IR wireless transmission demonstrates that a transmission waveform can be designed to remove the key channel impairments in a wireless IR system.
TL;DR: A novel method for high data rate transmissions in ultra-wideband communications systems is presented through the combination of conventional pulse position modulation and pulse shape modulation schemes that allows transmission of more bits of information in the same amount of time and using the same number of pulses.
Abstract: In this paper we present a novel method for high data rate transmissions in ultra-wideband (UWB) communications systems. This is achieved through the combination of conventional pulse position modulation and pulse shape modulation schemes. The result is a pulse shape and position modulation that allows transmission of more bits of information in the same amount of time and using the same number of pulses as the conventional schemes. A feature of the proposed system is that the allowable alphabet is limited so as to ensure equal power in transmission of all symbols. Symbol size can also be easily changed without significantly changing the hardware of the system. Theoretical error performance analysis of this system is also provided.
01 Dec 2003
TL;DR: The results show that the bit flipped schemes have a consistently lower average bit error rate and outage probabilities and the direct sequence, bit flipped, scheme has highest probability of outperforming both other schemes.
Abstract: This paper investigates three different performance metrics for three candidate combinations of multiple access and modulation schemes in ultra wideband radio. The schemes are compared for a single user, multipath channel at a fixed data rate. First, semianalytic expressions are developed for the probability of error with arbitrary multiple-access coding and amplitude or pulse position modulation, which are then reduced for the special cases of time hopped with bit flipping modulation, time hopped with pulse-position modulation and direct sequence with bit flipping modulation. Using Monte-Carlo simulation the bit error rate, probability of outage and probability of best performance are found. The results show that the bit flipped schemes have a consistently lower average bit error rate and outage probabilities and the direct sequence, bit flipped, scheme has highest probability of outperforming both other schemes. In addition, the effect of multipath arrival clustering in channel models was examined and it was found that the same performance curves could be generated with nonclustered arrivals, and hence channel models with nonclustered arrivals can safely be used in performance prediction.
18 Apr 2003
TL;DR: It is shown that dicode PPM gives a receiver sensitivity greater than digital PPM while operating at only four times the original data rate, which is significantly better than typical PCM sensitivities.
Abstract: Pulse position modulation (PPM) schemes have been proposed as a method of utilising the bandwidth available in optical fibres, with a 5-11 dB improvement in sensitivity being achieved compared to an equivalent pulse code modulation (PCM) system. However, this improvement comes at a cost. If digital PPM is used, the final data rate can be almost 23 times that of the original PCM, and this makes implementation difficult. The author describes a novel coding technique that combines dicode, a tertiary code sometimes used in magnetic recording, and digital PPM to form dicode PPM. It is shown that dicode PPM gives a receiver sensitivity greater than digital PPM while operating at only four times the original data rate. Original results presented predict that a high fibre bandwidth dicode PPM system can give sensitivities of -50.44 dBm and -44.27 dBm when operating with 155.52 Mbit/s and 1 Gbit/s PCM data, respectively. This should be compared to typical PCM sensitivities of -38 dBm and -28 dBm. It is also shown that dicode PPM outperforms digital PPM at low fibre bandwidths by 3.02 dB.
20 Mar 2003
TL;DR: It is shown, through numerical results, that bit error rates obtained byGaussian approximation underestimate the exact results and the errors due to Gaussian approximation become significant only for systems with low number of pulses per information bit.
Abstract: This paper is concerned with error rate performance analysis of ultra-wide bandwidth time-hopping multiple access radio networks employing binary pulse position modulation. Under the assumption of rectangular pulses, we derive an exact expression for the probability of bit error of a TH-CDMA/PPM signal subjected to K interferers in the AWGN channel. This is used to assess the accuracy of the Gaussian approximation commonly used in the performance analysis of UWB impulse radio networks. It is shown, through numerical results, that bit error rates obtained by Gaussian approximation underestimate the exact results. Moreover, the errors due to Gaussian approximation become significant only for systems with low number of pulses per information bit.
20 Mar 2003
TL;DR: The knowledge base of UWB MA performance characterization is expanded here using codes generated from a random integer selection process and a simulated annealing code generation process.
Abstract: This research focuses on performance of two ultra wide band (UWB) techniques for implementing multiple access (MA) communications. Specifically, a Gaussian monocycle with time hopping pulse position modulation (TH-PPM) and direct sequence binary phase shift keying (DS-BPSK) is considered. Previous research on UWB system performance using Gold spreading sequences forms the basis for this work. The knowledge base of UWB MA performance characterization is expanded here using codes generated from a random integer selection process and a simulated annealing code generation process. Communication performance is first validated for a single user operating over an AWGN channel and subsequently extended to incorporate multiusers, TH-PPM with Gold coding provides an average MA BER improvement factor of 2.0 /spl times/ 10/sup -2/ and 5.1 /spl times/ 10/sup -2/ over random integer and simulated annealing codes, respectively. Likewise, DS-BPSK with Gold coding provides an average MA BER improvement factor of 3.8/spl times/ 10/sup -4/ and 9.8 /spl times/ 10/sup -4/ over random integer and simulated annealing codes, respectively.
Patent•
21 Aug 2003TL;DR: In this article, a wireless transmission system which adaptively selects a plurality of modulation schemes according to variations in a propagation path characteristic, capable of estimating the modulation scheme of a received signal more easily with a substantially simple configuration.
Abstract: A wireless transmission system which adaptively selects a plurality of modulation schemes according to variations in a propagation path characteristic, capable of estimating the modulation scheme of a received signal more easily with a substantially simple configuration. This system adds priority order to modulation schemes to be candidates for modulation scheme estimation processing, carries out estimation processing on modulation schemes one by one in descending order of priority and confirms the modulation scheme of the received signal when predetermined likelihood is obtained.
16 Nov 2003
TL;DR: Validity of the standard Gaussian approximation (SGA) for modeling multi user interference (MUI) in impulse radio ultra wide band (IR-UWB) systems which do not implement power control is investigated.
Abstract: Validity of the standard Gaussian approximation (SGA) for modeling multi user interference (MUI) in impulse radio ultra wide band (IR-UWB) systems which do not implement power control is investigated. Analysis focuses on the case of UWB systems adopting binary pulse position modulation (2PPM) with a time hopping (TH) code division multiple access scheme. Theoretical predictions are compared vs. simulation outputs in order to quantify limitations of the SGA hypothesis.
TL;DR: 2PPM is shown to offer better performance than the other modulation schemes in presence of multiuser interference; increasing the spreading factor is proposed as a more effective strategy for SER reduction than the use of time diversity.
Abstract: A general method for the evaluation of the symbol error probability (SER) of ultra wideband (UWB) systems with various kind of modulation schemes (N-PAM, M-PPM, Bi-Orthogonal), in presence of multipath channel, multiuser and strong narrowband interference, is presented. This method is shown to be able to include all the principal multiaccess techniques proposed so far for UWB, time hopping (TH), direct sequence (DS) and optical orthogonal codes (OOC). A comparison between the performance of these multiple access and modulation techniques is given, for both ideal Rake receiver and minimum mean square error (MMSE) equalizer. It is shown that for all the analyzed multiple access schemes, a Rake receiver exhibits a high error floor in presence of narrowband interference (NBI) and that the value of the error floor is influenced by the spectral characteristics of the spreading code. As expected, an MMSE receiver offers better performance, representing a promising candidate for UWB systems. When the multiuser interference is dominant, all multiple access techniques exhibit similar performance under high-load conditions. If the number of users is significantly lower than the spreading factor, then DS outperforms both TH and OOC. Finally 2PPM is shown to offer better performance than the other modulation schemes in presence of multiuser interference; increasing the spreading factor is proposed as a more effective strategy for SER reduction than the use of time diversity.
TL;DR: In this paper, a short review of internal modulation is given, and new configurations with internal modulation are proposed to reduce the complexity of the beam-combining optics, and a modification to the implementation of internal modality is then investigated.
Abstract: The reduction of the thermal background emission from the local and exozodiacal dust clouds is a critical element for the success of ESA's space mission, DARWIN. Internal modulation, a technique using fast signal chopping, isolating the planetary signal from these noise sources, was proposed by Mennesson and Leger. In this paper, a short review of internal modulation is given, and new configurations with internal modulation are proposed to reduce the complexity of the beam-combining optics. A modification to the implementation of internal modulation is then investigated. It provides similar performance with a single detector and a greatly simplified optical layout: the number of beam-combiners is reduced by a factor of about two. The principle of inherent modulation is different from internal modulation in that no sub-interferometers are used: different phase shifts are applied to the input beams before recombination such that an asymmetric transmission map is obtained directly, without plus or minusπ/2 modulation as used in internal modulation. By combining the phase shifts and the input beams differently a transposed transmission map is obtained, allowing the signal to be chopped. During operations, multiplexing between the two interferometers is performed, such that at any time only one interferometer is being used.
10 Jan 2003
TL;DR: In this paper, a detailed analysis of the power spectral density (PSD) of the UWB signal is presented, which is determined by the spectrum of the basic UWB pulse; and pulse position modulation/dithering and pulse amplitude modulation.
Abstract: : The NETEX program is focused initially on understanding the effects of interference from ultra-wideband (UWB) transmitters on legacy military radio receivers, nearly all of which are narrowband (NB) relative to the UWB signal, which can have a bandwidth on the order of 1 GHz The purpose of this report is to document a set of mathematical models which have been developed to analyze the impact of UWB signals on NB receivers This analysis work is being done in parallel with a UWB interference testing program being conducted by other parties There are two main components to the work presented here The first is a detailed analysis of the power spectral density (PSD) of the UWB signal, which shows the distribution of the UWB transmit power over frequency The PSD is determined by (1) the spectrum of the basic UWB pulse; and (2) pulse position modulation/dithering and pulse amplitude modulation A clear understanding of the PSD is important, because the main factor that determines the impact on a NB receiver is the total average UWB interference power within the receiver passband This is demonstrated by the second main component of the report, which is a set of models describing the impact of UWB interference on several different representative receiver types, both digital and analog The PSD gives the average power-per-Hz as a function of frequency for the UWB signal The UWB PSD models developed here allow the PSD to be computed analytically for a wide range of different UWB signal types, and include the effects of pulse-position modulation (PPM), random or periodic pseudo-random dithering of the pulse position, modulation or random (or pseudo-random) coding of the pulse amplitude, modulation symbols that include multiple UWB frames (giving integration gain), and modulation of the actual pulse repetition frequency (PRF) by either a periodic PRF-modulating signal or by a random process such as a data signal
01 Dec 2003
TL;DR: This paper test and compare different modulation strategies to be used in ultra-wide band (IR-UWB) communications and proposes an M-ary modulation scheme that combines the shape and amplitude of the pulse to transmit the data, which is called pulse amplitude and shape modulation (PASM).
Abstract: In this paper we test and compare different modulation strategies to be used in ultra-wide band (IR-UWB) communications. In the UWB systems of interest in this work the information is conveyed by short-duration pulses; the modulation scheme determine how the data stream is to be transmitted over those pulses. Here we test and compare several schemes based on three types of modulation. The first type is the pulse position modulation (PPM), which includes a pulse delay according to the data to be transmitted. The second is the recently proposed pulse shape modulation (PSM), that uses a different pulse shape to each data. The third one, proposed in this paper, is an M-ary modulation scheme that combines the shape and amplitude of the pulse to transmit the data, which we call pulse amplitude and shape modulation (PASM). Other M-ary schemes are tested, including the recent orthogonal M-ary PSM, based on orthogonal Hermite functions, and a new quaternary PPM scheme, also proposed here. All schemes are tested over an AWG channel.
01 Jan 2003
TL;DR: An improved statistical blind modulation detection method based on the Kullback-Leibler distance is proposed for OFDM based wireless communication systems and shows results that outperforms similar previously proposed algorithms.
Abstract: Adaptive modulation is a method to increase the data capacity, throughput and efficiency of time division du- plexed wireless communication systems. In adaptive modulation, the transmitter continually monitors the dynamic channel and adjusts the transmission parameters such as modulation order, coding rate etc. accordingly. Blind modulation detection schemes play an important role in adaptive systems to eliminate the need for transmitting modulation information, thereby increasing spectral efficiency. In this paper, an improved statistical blind modulation detection method based on the Kullback-Leibler distance is proposed for OFDM based wireless communication systems. Simulation results show that this blind modulation detection algorithm outperforms similar previously proposed algorithms.
13 Oct 2003
TL;DR: A statistical model is developed that predicts bit error performance for binary offset pulse position modulation as a function of near/far density and power for varying discrimination thresholds and it is found that even a small number of very near interferers can greatly reduce the performance of a system without blanking or discrimination.
Abstract: A simple chip discrimination technique is presented for use with ultra wide band (UWB), impulse radio (IR) that improves performance for large near/far interference ratios. A typical spread-spectrum IR that employs a matched filter sum for bit decisions is susceptible to small numbers of large power pulses that can dominate the bit decision threshold statistics. This paper describes a technique for chip discrimination prior to the spreading summation that can greatly reduce the effects of large near/far interferers. The technique exploits the unique time domain characteristics that only UWB systems can provide. A statistical model is developed that predicts bit error performance for binary offset pulse position modulation (PPM) as a function of near/far density and power for varying discrimination thresholds. We find that even a small number of very near interferers can greatly reduce the performance of a system without blanking or discrimination. Results show substantial improvement using this method for near interferers with near/far power ratios greater than 20 dB.