Spectral shape of UWB signals influence of modulation format, multiple access scheme and pulse shape

Nakache, Y.-P.; Molisch, Andreas F.

doi:10.1109/vetecs.2003.1208843

Cited by 72 publications

(60 citation statements)

References 4 publications

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“…In "classical" impulse radio, the polarity of those pulses representing an information symbol is always the same, whether PPM or BPSK is employed [10], [11]. Recently, pulse-based polarity randomization was proposed [12], where each pulse has a random polarity code in addition to the modulation scheme, providing additional robustness against MAI [13] and helping to optimize the spectral shape according to US Federal Communications Commission (FCC) specifications [14]. Due to the large bandwidth, UWB signals have a much higher temporal resolution than conventional narrowband or wideband signals.…”

Section: Introductionmentioning

confidence: 99%

Energy Efficient Power Control in Impulse Radio UWB Wireless Networks

Bacci

Luise

Poor

et al. 2007

IEEE J. Sel. Top. Signal Process.

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In this paper, a game-theoretic model for studying power control for wireless data networks in frequency-selective multipath environments is analyzed. The uplink of an impulse-radio ultrawideband system is considered. The effects of self-interference and multiple-access interference on the performance of generic Rake receivers are investigated for synchronous systems. Focusing on energy efficiency, a noncooperative game is proposed in which users in the network are allowed to choose their transmit powers to maximize their own utilities, and the Nash equilibrium for the proposed game is derived.It is shown that, due to the frequency selective multipath, the noncooperative solution is achieved at different signal-to-interference-plus-noise ratios, depending on the channel realization and the type of Rake receiver employed. A large-system analysis is performed to derive explicit expressions for the achieved utilities. The Pareto-optimal (cooperative) solution is also discussed and compared with the noncooperative approach.

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Section: Introductionmentioning

confidence: 99%

Energy Efficient Power Control in Impulse Radio UWB Wireless Networks

Bacci

Luise

Poor

et al. 2007

IEEE J. Sel. Top. Signal Process.

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“…The three quantities T s , T f , and T c satisfy the following relationship: Time-hopping (TH) and polarity scrambling are applied on each symbol to obtain processing gain, to combat multipleaccess interference (MAI), and to smooth the signal spectrum. Specifically, each pulse pair is delayed by a pseudorandom time [6], and multiplied with a pseudorandom polarity scrambling that can take on the values ±1 [24]; this can be easily undone at the receiver.…”

Section: A Basic Ideamentioning

confidence: 99%

Hybrid Ultrawideband Modulations Compatible for Both Coherent and Transmit-Reference Receivers

Zhao

Orlik

Molisch³

et al. 2007

IEEE Trans. Wireless Commun.

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This paper considers signaling schemes for heterogeneous ultrawideband communications networks that contain both coherent (rake) and transmitted-reference (TR) receivers. While coherent receivers are capable of receiving TR signals, they do so with a 3 dB penalty, because they cannot make use of the energy invested into the reference pulse. We propose a new signaling scheme that avoids this drawback, by encoding redundant information on the reference pulse. The resulting scheme does not affect the operation of a TR receiver, while recovering the 3 dB penalty and furthermore providing an additional 1.7 dB coding gain to a coherent uncoded binary scheme. This can be explained by interpreting the scheme as a trellis-coded modulation. We also provide an alternative implementation that can be viewed as a recursive systematic convolutional encoder. Combining this version further with a simple forward error correction encoder results in a concatenated code that can be decoded iteratively, providing a bit-error rate of 10-3 at 2.8 dB signal-to-noise ratio in additive white Gaussian noise. The convergence behavior of this iterative code is analyzed by using extrinsic information transfer charts. IEEE Transactions on Wireless CommunicationsThis work may not be copied or reproduced in whole or in part for any commercial purpose. Permission to copy in whole or in part without payment of fee is granted for nonprofit educational and research purposes provided that all such whole or partial copies include the following: a notice that such copying is by permission of Mitsubishi Electric Research Laboratories, Inc.; an acknowledgment of the authors and individual contributions to the work; and all applicable portions of the copyright notice. Copying, reproduction, or republishing for any other purpose shall require a license with payment of fee to Mitsubishi Electric Research Laboratories, Inc. All rights reserved. Abstract-This paper considers signaling schemes for heterogeneous ultrawideband communications networks that contain both coherent (rake) and transmitted-reference (TR) receivers. While coherent receivers are capable of receiving TR signals, they do so with a 3 dB penalty, because they cannot make use of the energy invested into the reference pulse. We propose a new signaling scheme that avoids this drawback, by encoding redundant information on the reference pulse. The resulting scheme does not affect the operation of a TR receiver, while recovering the 3 dB penalty and furthermore providing an additional 1.7 dB coding gain to a coherent uncoded binary scheme. This can be explained by interpreting the scheme as a trellis-coded modulation. We also provide an alternative implementation that can be viewed as a recursive systematic convolutional encoder. Combining this version further with a simple forward error correction encoder results in a concatenated code that can be decoded iteratively, providing a bit-error rate of 10 −3 at 2.8 dB signal-to-noise ratio in additive white Gaussian noise. The convergence beh...

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“…The c j denote a (pseudo-)random integer sequence with values between 0 and N c − 1, which determines the TH sequence; N c is the number of chips per frame. The d j denote a pseudo-random sequence of +1 and −1 that ensures a zero-mean output and is also helpful in shaping the transmit spectrum [22] according to the FCC rules [1]. We assume that the support of w tx (t), the unit-energy transmit waveform, extends only over one chip duration.…”

Section: A Transmit Signalmentioning

confidence: 99%

“…BPSK gives a better receiver SNR [21], and the polarity randomization results in a transmit spectrum that better exploits the FCC mask [22] • we analyze the impact of IFI, and the interference from the reference pulse to the data pulse. This is vital for systems with moderate to high data rates • we simulate the performance of a TR scheme in the standardized IEEE 802.…”

Section: Introductionmentioning

confidence: 99%