Showing papers on "Pulse-position modulation published in 2005"
TL;DR: The performance of a direct-detection, avalanche photodiode-based free-space optical (FSO) communication system in terms of the overall bit-error rate is characterized in order to shed light on the impact of turbulence on the overall performance.
Abstract: In this paper, we characterize the performance of a direct-detection, avalanche photodiode-based free-space optical (FSO) communication system in terms of the overall bit-error rate. The system of interest uses pulse-position modulation (PPM) and is subjected to scintillation due to optical turbulence. Two scenarios are considered. In one case, a weak turbulence (clear-air) scenario is considered, for which the received signal intensity may be modeled as a log-normal random process. In the other case, we consider a negative exponentially distributed received signal intensity. To arrive at the desired results, it is assumed that the system uses a binary PPM (BPPM) modulation scheme. Furthermore, it is assumed that the receiver thermal noise is nonnegligible, and that the average signal intensity is large enough to justify a Gaussian approximation at the receiver. Union bound is used to assess the performance of M-ary PPM systems using the results of the BPPM scenario. Numerical results are presented for the BPPM case to shed light on the impact of turbulence on the overall performance.
242 citations
TL;DR: A modification of the Alamouti code originally proposed for RF wireless applications is described that allows it to be applied in scenarios such as free-space optical communication with direct detection where unipolar modulations like pulse-position modulation and on-off keying are traditionally used to convey the information.
Abstract: A modification of the Alamouti code originally proposed for RF wireless applications is described that allows it to be applied in scenarios such as free-space optical communication with direct detection where unipolar modulations like pulse-position modulation and on-off keying are traditionally used to convey the information. The modification of the code and associated decision metric is such as to maintain all of the desirable properties of the original scheme.
231 citations
TL;DR: This work focuses upon the use of multiple-pulse-position-modulation as a power-efficient transmission format, with signal repetition across the laser array, for atmospheric, line-of-sight optical communication, and on capacity for coded transmission.
Abstract: We study the use of multiple laser transmitters combined with multiple photodetectors for atmospheric, line-of-sight optical communication, and focus upon the use of multiple-pulse-position-modulation as a power-efficient transmission format, with signal repetition across the laser array. Ideal (photon counting) photodetectors are assumed, with and without background radiation. The resulting multiple-input/multiple-output channel has the potential for combating fading effects on turbulent optical channels, for which both log-normal and Rayleigh-fading models are treated. Our focus is upon symbol error probability for uncoded transmission, and on capacity for coded transmission. Full spatial diversity is obtained naturally in this application.
226 citations
TL;DR: The effects of atmospheric turbulence, background light, source extinction ratio, amplified spontaneous emission, and receiver thermal noise are studied in the context of a semiclassical photon-counting approach and results are presented using a conditional Gaussian approximation method.
Abstract: Atmospheric optical communication systems that use optical preamplifiers and diversity reception are addressed. The particular diversity techniques that are investigated include aperture averaging, linear combining, and adaptive optics. On-off keying and binary pulse position modulation are considered. The effects of atmospheric turbulence, background light, source extinction ratio, amplified spontaneous emission, and receiver thermal noise are studied in the context of a semiclassical photon-counting approach. Numerical results are presented using a conditional Gaussian approximation method. By this method, we can measure the power penalty incurred under various operating conditions as well as the link margin improvement due to optical preamplification and diversity reception.
118 citations
01 May 2005
TL;DR: It is shown that the standard decoder can be simplified by precomputing certain edge likelihoods on a reduced-edge trellis, without approximation or degradation, and that an M -input ∗ max function may be distributed and pipelined.
Abstract: We present an error-control coding technique for optical communications It consists of the serial concatenation of an outer convolutional code, an interleaver, a bit-accumulator, and pulse-position modulation (PPM) We refer to the coded modulation as serially concatenated PPM, or SCPPM The encoding is accomplished with simple shift register operations and a table look-up to map code bits to PPM symbols The code is decoded with an iterative demodulator–decoder, using standard turbo-decoding techniques For system constraints typical of the Mars Laser Communications Demonstration, simulations indicate operation within 1 dB of capacity We show that the standard decoder can be simplified by precomputing certain edge likelihoods on a reduced-edge trellis, without approximation or degradation, and that an M -input ∗ max function may be distributed and pipelined A further simplification allows one to discard many of the channel observables, with negligible degradation
117 citations
Abstract: In this paper, the performance of a binary phase shift keyed random time-hopping impulse radio system with pulse-based polarity randomization is analyzed. The effects of interframe interference and multiple-access interference on the performance of a generic Rake receiver are investigated for asynchronous systems in frequency-selective environments. A key step is to model the asynchronous system as a chip-synchronous system with uniformly distributed timing jitter for the transmitted pulses of interfering users. This model allows the analytical technique developed for the synchronous case to be extended to the asynchronous case and allows the derivation of closed-form equations for the bit error probability in various Rake receiver architectures. It is shown that a Gaussian approximation can be used for both multiple-access and interframe interference as long as the number of frames per symbols is large (typically, at least 5), whereas there is no minimum requirement for the number of users for the equations to hold. It is observed that under many circumstances, the chip-synchronous case shows a worse bit error probability performance than the asynchronous case; the amount of the difference depends on the autocorrelation function of the ultra-wideband pulse and the signal-to-interference-plus-noise-ratio of the system. Simulations studies support the approximate analysis.
112 citations
TL;DR: It is illustrated that the reception quality of a UWB impulse radio is highly sensitive to both timing acquisition and tracking errors, and the energy capture capability of a RAKE combiner can be severely compromised by mistiming.
Abstract: We investigate timing tolerances of ultra wideband (UWB) impulse radios. We quantify the bit-error-rate (BER) sensitivity to epoch timing offset under different operating conditions, including frequency flat fading channels, dense multipath fading channels, multiple access with time hopping, and various receiver types including sliding correlators and RAKE combiners. Our systematic approach to BER derivations under mistiming can be extended to a wide range of channel fading types. Through analyses and simulations, we illustrate that the reception quality of a UWB impulse radio is highly sensitive to both timing acquisition and tracking errors. In particular, time-hopping-based multiple-access systems exhibit little tolerance to acquisition errors, and the energy capture capability of a RAKE combiner can be severely compromised by mistiming.
87 citations
TL;DR: It is shown that N-ary BPPM has better performance than N-ARY PPM with the same throughput and half the computational complexity.
Abstract: In this paper, we propose a new modulation scheme called biorthogonal pulse position modulation (BPPM) for ultra-wideband (UWB) communication systems. A set of N=2/sup k+1/ BPPM signals are constructed from 2/sup k/ orthogonal PPM signals by including the antipodal version of the orthogonal PPM signals. The channel capacity of BPPM is determined for a time-hopping multiple access UWB communication system. The error probability and performance bounds are derived for a multiuser environment. It is shown that N-ary BPPM has better performance than N-ary PPM with the same throughput and half the computational complexity.
81 citations
TL;DR: In this paper, a general class of MA communication systems that use both types of processing gain is presented, and both IR and RCDMA systems are demonstrated to be two special cases of this more generalclass of systems.
Abstract: One of the features characterizing almost every multiple-access (MA) communication system is the processing gain. Through the use of spreading sequences, the processing gain of random code-division multiple-access (RCDMA) systems, or any other code-division multiple-access (CDMA) systems, is devoted to both bandwidth expansion and orthogonalization of the signals transmitted by different users. Another type of MA system is impulse radio (IR). IR systems promise to deliver high data rates over ultra-wideband channels with low-complexity transmitters and receivers. In many aspects, IR systems are similar to time-division MA systems, and the processing gain of IR systems represents the ratio between the actual transmission time and the total time between two consecutive transmissions (on-plus-off-to-on ratio). While CDMA systems, which constantly excite the channel, rely on spreading sequences to orthogonalize the signals transmitted by different users, IR systems transmit a series of short pulses, and the orthogonalization between the signals transmitted by different users is achieved by the fact that most of the pulses do not collide with each other at the receiver. In this paper, a general class of MA communication systems that use both types of processing gain is presented, and both IR and RCDMA systems are demonstrated to be two special cases of this more general class of systems. The bit-error rate of several receivers as a function of the ratio between the two types of processing gain is analyzed and compared, under the constraint that the total processing gain of the system is large and fixed. It is demonstrated that in non-intersymbol interference (ISI) channels, there is no tradeoff between the two types of processing gain. However, in ISI channels, a tradeoff between the two types of processing gain exists. In addition, the suboptimality of RCDMA systems in frequency-selective channels is established.
78 citations
TL;DR: It is shown that for M=2.2, 2N-ary PPAM signals have better performance than 2n-ary PPM with the same throughput and half the computational complexity.
Abstract: In this letter, we propose a new modulation scheme called pulse position amplitude modulation (PPAM) for ultra-wideband (UWB) communication systems. PPAM combines pulse position modulation and pulse amplitude modulation to provide good system performance and low computational complexity. The channel capacity of PPAM is determined for a time-hopping multiple-access UWB communication system. The error probability and performance bounds are derived for a multiuser environment.
69 citations
TL;DR: The proposed Pre-RAKE diversity combining techniques are effective for the UWB-IR systems to achieve good error rate performance, while keeping the complexity of the receiver low and it is shown that the S-Pre-RAke diversity combining is effective in achieving good error rates performance with less channel information.
Abstract: Since Ultra Wideband Impulse Radio (UWB-IR) system can resolve many paths and is thus rich in multipath diversity, the use of Rake diversity combining is very effective. In the Rake diversity combining, the bit error rate (BER) is improved with the increase of the number of fingers. The Pre-Rake diversity combining is known as another technique to achieve the performance equivalent to the Rake diversity combining without increasing the receiver complexity. In the Pre-Rake diversity combining, the transmitted signals are scaled and delayed according to the delay and strength of the multipath. In this paper, we propose Pre-Rake diversity combining techniques for UWB systems, All-Pre-Rake (A-Pre-Rake) diversity combining using perfect channel information, Selective-Pre-Rake (S-Pre-Rake) diversity combining using the information on the L strongest paths, and Partial-Pre-Rake (P-Pre-Rake) diversity combining using the information on the first L paths. From the results of our computer simulation for UWB-IR systems in IEEE 802.15 UWB multipath channel model, we show that the proposed Pre-Rake diversity combining techniques are effective for the UWB-IR systems to achieve good error rate performance, while keeping the complexity of the receiver low. We also show that the S-Pre-Rake diversity combining is effective to achieve good error rate performance with less channel information.
06 Mar 2005
TL;DR: In this paper, a variable duty-cycle M-ary pulse-position modulation (M-PPM) with coding is investigated experimentally using a simple, multi-rate nearly quantum-limited receiver with throughputs ranging from 1.25 Gbit/s, in the binary case, to 78 M bit/s for M=256.
Abstract: Photon-efficient optical communications using variable-duty-cycle M-ary pulse-position modulation (M-PPM) with coding is investigated experimentally using a simple, multi-rate nearly quantum-limited receiver with throughputs ranging from 1.25 Gbit/s, in the binary case, to 78 Mbit/s, for M=256.
TL;DR: It is illustrated that the reception quality of a UWB impulse radio is highly sensitive to both timing acquisition and tracking errors, and the bit-error rate (BER) sensitivity to epoch timing offset is quantified under various radio operating conditions.
Abstract: We investigate timing tolerances of ultra-wideband (UWB) impulse radios. We quantify the bit-error rate (BER) sensitivity to epoch timing offset under different operating conditions, including frequency-flat fading channels, dense multipath fading channels, multiple access with time hopping, and various receiver types including sliding correlators and RAKE combiners. For a general correlation-based detector, we derived in Part I unifying expressions for the decision statistics as well as BER formulas under mistiming, given fixed channel realizations. In Part II, we provide a systematic approach to BER analysis under mistiming for fading channels. The BER is expressed in terms of the receiver's energy capture capability, which we quantify under various radio operating conditions. We also develop the optimal demodulator in the presence of timing offset and show a proper design of the correlation-template that is robust to mistiming. Through analyses and simulations, we illustrate that the reception quality of a UWB impulse radio is highly sensitive to both timing acquisition and tracking errors.
Posted Content•
TL;DR: In this article, the optimal choice of the fraction of time used for transmission depends on the spectral efficiency of the signal modulation, and the general principle is demonstrated by comparing the channel conditions that allow different modulations to achieve the capacity in the limit.
Abstract: Wide band systems operating over multipath channels may spread their power over bandwidth if they use duty cycle. Channel uncertainty limits the achievable data rates of power constrained wide band systems; Duty cycle transmission reduces the channel uncertainty because the receiver has to estimate the channel only when transmission takes place. The optimal choice of the fraction of time used for transmission depends on the spectral efficiency of the signal modulation. The general principle is demonstrated by comparing the channel conditions that allow different modulations to achieve the capacity in the limit. Direct sequence spread spectrum and pulse position modulation systems with duty cycle achieve the channel capacity, if the increase of the number of channel paths with the bandwidth is not too rapid. The higher spectral efficiency of the spread spectrum modulation lets it achieve the channel capacity in the limit, in environments where pulse position modulation with non-vanishing symbol time cannot be used because of the large number of channel paths.
TL;DR: An analytical expression for the signal-to-noise ratio (SNR) of the pulse position modulated (PPM) signal in an ultrawideband (UWB) channel with multiple transmit and receive antennas is presented.
Abstract: This paper presents an analytical expression for the signal-to-noise ratio (SNR) of the pulse position modulated (PPM) signal in an ultrawideband (UWB) channel with multiple transmit and receive antennas. A generalized fading channel model that can capture the cluster property and the highly dense multipath effect of the UWB channel is considered. Through simulations, it is demonstrated that the derived analytical model can accurately estimate the mean and variance properties of the pulse-based UWB signals in a frequency-selective fading channel. Furthermore, the authors investigate to what extent the performance of the PPM-based UWB system can be further enhanced by exploiting the advantage of multiple transmit antennas or receive antennas. Numerical results show that using multiple transmit antennas in the UWB channel can improve the system performance in the manner of reducing signal variations. However, because of already possessing rich diversity inherently in the UWB channel, using multiple transmit antennas does not provide diversity gain in the strict sense [i.e., improving the slope of bit error rate (BER) versus SNR] but can possibly reduce the required fingers of the RAKE receiver for the UWB channel. Furthermore, because multiple receive antennas can provide higher antenna array combining gain, the multiple receive antennas technique can be used to improve the coverage performance for the UWB system, which is crucial for a UWB system due to the low transmission power operation.
TL;DR: It is found that a bilevel receiver provides 3-dB gain in optical signal-to-noise ratio sensitivity and is more robust against chromatic dispersion for either nonreturn-to -zero or return- to-zero modulation.
Abstract: We examine the performance of optical 8-ary differential phase-shift keying transmission systems according to the type of receiver structure and modulation format. Compared with the approach based on a multilevel decision, we found that a bilevel receiver provides 3-dB gain in optical signal-to-noise ratio sensitivity and is more robust against chromatic dispersion for either nonreturn-to-zero or return-to-zero modulation.
TL;DR: Simulation results demonstrate that high data rate communication is achieved by the proposed orthonormal pulses via pulse shape modulation and pulse position modulation.
Abstract: In this letter, we propose novel pulses which not only meet the power spectral mask of the Federal Communications Commission (FCC) for indoor Ultra-wideband (UWB) systems but also preserve orthogonality at the correlation receiver. The proposed pulses are derived from a parametric closed-form solution. Thus, multiple orthonormal pulses that comply with the FCC mask without additional frequency shifting or bandpass filters can be generated for high data rate communications or multiple access schemes. Simulation results demonstrate that high data rate communication is achieved by the proposed orthonormal pulses via pulse shape modulation and pulse position modulation.
TL;DR: In this article, the authors demonstrate the high potentiality in terms of data rate and multiple access of a novel 60GHz WLAN architecture for smart objects and indoor communication systems based on the up-conversion of an ultrawide-bandwidth impulse radio signal (IR-UWB) in the 60GHz frequency range to benefit of the natural advantages of the UWB technique while avoiding the baseband limitations.
Abstract: The purpose of this letter is to demonstrate the high potentiality in terms of data rate and multiple access of a novel 60-GHz WLAN architecture for smart objects and indoor communication systems This approach is based on the up-conversion of an ultrawide-bandwidth impulse radio signal (IR-UWB) in the 60-GHz frequency range to benefit of the natural advantages of the UWB technique while avoiding the baseband limitations First results about the pulse generator and receiver architecture are discussed
12 Jun 2005
TL;DR: In this article, a gated pulse generator incorporating two modulation schemes for use in an ultra-wideband impulse radio system was proposed, where a pseudo-noise sequence prescaler modulates the impulses with specific modulation schemes, such as pulse position, bi-phase modulation or the combination of both.
Abstract: In this paper, we propose a gated pulse generator incorporating two modulation schemes for use in an ultra-wideband impulse radio system. A pseudo-noise sequence prescaler modulates the impulses with specific modulation schemes, such as pulse position, bi-phase modulation or the combination of both. The resulting gated monocycle generator is designed in Jazz Semiconductor BiCMOS SiGe technology. Measurements validate the circuit operation over a supply voltage of 2.7 V and a power consumption of 243 mW. The output monocycles approximate Gaussian monocycles, having a pulse duration of 250 ps. Proper modulations in time are confirmed.
28 Sep 2005
TL;DR: In this paper, a novel technique for generation of micro- or millimeter-wave pulses using optical frequency-shift-keying (FSK) modulation was proposed, which can be obtained as an optical beat of two spectral components.
Abstract: We proposed a novel technique for generation of micro- or millimeter-wave pulses using optical frequency-shift-keying (FSK) modulation. FSK signals were obtained by an integrated four optical phase modulators. The pulses can be obtained as an optical beat of two spectral components, during transient FSK state which is shorter than 100 ps.
01 May 2005
TL;DR: The capacity of MPPM can be significantly higher, up to two times, than conventional pulseposition modulation (PPM) in a high average-power region for which the optimal M for conventional PPM is approximately 16 or lower.
Abstract: Next, we present an expression for the capacity of MPPM and show how to choose n ∈ {1, 2, · · ·} and M ∈ {2, 3, · · ·} to maximize capacity when average power, peak power, and bandwidth constraints are simultaneously imposed. The capacity of MPPM can be significantly higher, up to two times, than conventional pulseposition modulation (PPM) in a high average-power region for which the optimal M for conventional PPM is approximately 16 or lower. In lower average-power regions where the optimal M is higher, MPPM offers a negligible increase in capacity.
TL;DR: DAPPM yields advantages over PPM, DPPM, and DH-PIM in terms of bandwidth requirements, capacity, and peak-to-average power ratio (PAPR), and it is shown that the performance of DAPPM can be improved with MLSD, chip-rate DFE, and multichip- rate DFE.
Abstract: We propose a novel differential amplitude pulse-position modulation (DAPPM) for indoor optical wireless communications. DAPPM yields advantages over PPM, DPPM, and DH-PIMα in terms of bandwidth requirements, capacity, and peak-to-average power ratio (PAPR). The performance of a DAPPM system with an unequalized receiver is examined over nondispersive and dispersive channels. DAPPM can provide better bandwidth and/or power efficiency than PAM, PPM, DPPM, and DH-PIMα depending on the number of amplitude levels A and the maximum length L of a symbol. We also show that, given the same maximum length, DAPPM has better bandwidth efficiency but requires about 1 dB and 1.5 dB more power than PPM and DPPM, respectively, at high bit rates over a dispersive channel. Conversely, DAPPM requires less power than DH-PIM2. When the number of bits per symbol is the same, PAM requires more power, and DH-PIM2 less power, than DAPPM. Finally, it is shown that the performance of DAPPM can be improved with MLSD, chip-rate DFE, and multichip-rate DFE.
TL;DR: This letter investigates generalized-likelihood-ratio-test (GLRT) detectors for ultra-wideband (UWB) impulse radio systems employing two alternative signaling schemes using the data pulse received in the previous frame as a template waveform in the current frame.
Abstract: This letter investigates generalized-likelihood-ratio-test (GLRT) detectors for ultra-wideband (UWB) impulse radio systems employing two alternative signaling schemes. One is the so-called transmitted reference method where, in each time frame, a reference pulse is transmitted prior to the data pulse. The other is the differential transmitted reference scheme, wherein the data pulse received in the previous frame is used as a template waveform in the current frame. The two detectors are compared in terms of bit error rate performance.
05 Dec 2005
TL;DR: Simulation results proves that the assumption of sum of tone interferers is a good approximation for an OFDM interferer and analytical results show that the frequency selectivity of the channel of the interferer plays an important role on the performance.
Abstract: This paper evaluates the performance of time hopping (TH) pulse position modulation (PPM) and TH binary pulse amplitude modulation (BPAM) systems in the presence of multi-carrier interference. In particular, we derive closed-form bit error probability (BEP) expressions for binary coherent TH-PPM and TH-BPAM systems based on matched filter reception by approximating the multi-carrier interference as sum of tone interferers and considering different scenarios such as AWGN as well as frequency-selective channels. Simulation results proves that the assumption of sum of tone interferers is a good approximation for an OFDM interferer and our analytical results show that the frequency selectivity of the channel of the interferer plays an important role on the performance.
IBM1
TL;DR: Simulation of a sensor network scenario without transmit power control shows that the design rules that make the collision probability insensitive to the asynchronism also do this for the bit-error rate (BER).
Abstract: Popular multiple-access schemes for asynchronous users that access the channel at randomly or pseudorandomly chosen time instances are ALOHA and TH-PPM. To cope with the randomness of these signals can be challenging for a receiver. In this paper, an uncoordinated but deterministic multiple-access scheme is proposed that can eliminate some of these drawbacks. The principle of this scheme is that each user transmits with an individual pulse or packet rate, while the duty cycle of the user signals is kept very low. As the access to the channel is asynchronous, collisions will occur. An analytical expression is derived for the collision probability, which depends on the asynchronism between the users. Design rules are derived that make the collision probability independent of the asynchronism. In practical implementations, deviations from the design values for the user rates will occur, and the length of a data packet is limited; the impact of these aspects on the collision probability is discussed. Simulation of a sensor network scenario without transmit power control shows that the design rules that make the collision probability insensitive to the asynchronism also do this for the bit-error rate (BER). The comparison of simulation results for RDMA with binary antipodal modulation and random TH-PSK, which is related to TH-PPM, yields very similar bit-error rates.
TL;DR: The impact of narrowband interference on two ultra wideband (UWB) systems is analyzed and the signal-to-noise ratio (SNR) at the decision device of a correlation receiver is computed, assuming that the NBI is wide sense stationary and that the channel is frequency-selective.
Abstract: The impact of narrowband interference (NBI) on two ultra wideband (UWB) systems is analyzed. The two systems are impulse radio (IR) and a variation of it, termed direct-sequence IR (DS-IR). The signal-to-noise ratio (SNR) at the decision device of a correlation receiver is computed for both systems, assuming that the NBI is wide sense stationary and that the channel is frequency-selective. The SNR is expressed by means of a simple equation involving the signal and the interference spectrum. Next, a statistical model for the interference is introduced, considering the interference as the sum of a given number of sinusoidal signals with random powers and frequencies. The bit-error rate of IR and DS-IR is derived. The results are then specialized and compared with simulations in three case studies of practical interest, where the NBI is a single jammer with deterministic power and frequency, a multitone signal with random frequencies, or a grid of interfering signals with random powers.
01 Nov 2005
TL;DR: A 100-Mb/s pulse position modulation generator is presented for impulse-radio ultra-wideband applications and a mixed-mode calibration circuit is used to calibrate the output buffer of the delay-locked loop.
Abstract: A 100-Mb/s pulse position modulation generator is presented for impulse-radio ultra-wideband applications. The pulse generator provides a data rate of 100 Mb/s and a pulse width of 1 ns. To achieve an accurate pulse position and pulse width, a mixed-mode calibration circuit is used to calibrate the output buffer of the delay-locked loop. The proposed circuit has been fabricated in a 0.35-mum CMOS process. After the calibration, the measurement results show that both the pulse-width error and the pulse-position error are less than 4%
TL;DR: An efficient, low-cost implementation of time-hopping impulse radio that fulfills the spectral mask mandated by the FCC and is suitable for high-data-rate, short-range communications.
Abstract: We present an efficient, low-cost implementation of time-hopping impulse radio that fulfills the spectral mask mandated by the FCC and is suitable for high-data-rate, short-range communications. Key features are (i) all-baseband implementation that obviates the need for passband components, (ii) symbol-rate (not chip rate) sampling, A/D conversion, and digital signal processing, (iii) fast acquisition due to novel search algorithms, and (iv) spectral shaping that can be adapted to accommodate different spectrum regulations and interference environments. Computer simulations show that this system can provide 110 Mbps at 7-10 m distance, as well as higher data rates at shorter distances under FCC emissions limits. Due to the spreading concept of time-hopping impulse radio, the system can sustain multiple simultaneous users, and can suppress narrowband interference effectively.
12 Jun 2005
TL;DR: New transmitter architectures utilizing nonlinear power amplifiers when transmitting linearly modulated signals are studied and the emphasis is on bandpass pulse-width modulation (BP-PWM).
Abstract: New transmitter architectures utilizing nonlinear power amplifiers when transmitting linearly modulated signals are studied The emphasis is on bandpass pulse-width modulation (BP-PWM) for which both theory and implementation proposals are presented