2,287 research outputs found
Energy-Efficient Power Control in Impulse Radio UWB Wireless Networks
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.Comment: Submitted to the IEEE Journal on Selected Topics in Signal Processing
- Special issue on Performance Limits of Ultra-Wideband System
A New Transmitted Reference Pulse Cluster Based Ultra-Wideband Transmitter Design
An energy efficient ultra-wideband (UWB) transmitter based on the novel
transmitted reference pulse cluster (TRPC) modulation scheme is presented. The
TRPC-UWB transmitter integrates, namely, wideband active baluns, wideband I-Q
modulator based up-conversion mixer, and differential to single-ended
converter. The integrated circuits of TRPC-UWB front end is designed and
implemented in the 130-nm CMOS process technology. the measured worst-case
carrier leakage suppression is 22.4 dBc, while the single sideband suppression
is higher than 31.6 dBc, operating at the frequency from 3.1 GHz to 8.2 GHz.
With adjustable data rate of 10 to 300 Mbps, the transmitter achieves a high
energy efficiency of 38.4 pJ/pulse.Comment: 4 page, 8 figure
Performance evaluation of non-prefiltering vs. time reversal prefiltering in distributed and uncoordinated IR-UWB ad-hoc networks
Time Reversal (TR) is a prefiltering scheme mostly analyzed in the context of centralized and synchronous IR-UWB networks, in order to leverage the trade-off between communication performance and device complexity, in particular in presence of multiuser interference. Several strong assumptions have been typically adopted in the analysis of TR, such as the absence of Inter-Symbol / Inter-Frame Interference (ISI/IFI) and multipath dispersion due to complex signal propagation. This work has the main goal of comparing the performance of TR-based systems with traditional non-prefiltered schemes, in the novel context of a distributed and uncoordinated IR-UWB network, under more realistic assumptions including the presence of ISI/IFI and multipath dispersion. Results show that, lack of power control and imperfect channel knowledge affect the performance of both non-prefiltered and TR systems; in these conditions, TR prefiltering still guarantees a performance improvement in sparse/low-loaded and overloaded network scenarios, while the opposite is true for less extreme scenarios, calling for the developement of an adaptive scheme that enables/disables TR prefiltering depending on network conditions
Performance Analysis and Enhancement of Multiband OFDM for UWB Communications
In this paper, we analyze the frequency-hopping orthogonal frequency-division
multiplexing (OFDM) system known as Multiband OFDM for high-rate wireless
personal area networks (WPANs) based on ultra-wideband (UWB) transmission.
Besides considering the standard, we also propose and study system performance
enhancements through the application of Turbo and Repeat-Accumulate (RA) codes,
as well as OFDM bit-loading. Our methodology consists of (a) a study of the
channel model developed under IEEE 802.15 for UWB from a frequency-domain
perspective suited for OFDM transmission, (b) development and quantification of
appropriate information-theoretic performance measures, (c) comparison of these
measures with simulation results for the Multiband OFDM standard proposal as
well as our proposed extensions, and (d) the consideration of the influence of
practical, imperfect channel estimation on the performance. We find that the
current Multiband OFDM standard sufficiently exploits the frequency selectivity
of the UWB channel, and that the system performs in the vicinity of the channel
cutoff rate. Turbo codes and a reduced-complexity clustered bit-loading
algorithm improve the system power efficiency by over 6 dB at a data rate of
480 Mbps.Comment: 32 pages, 10 figures, 1 table. Submitted to the IEEE Transactions on
Wireless Communications (Sep. 28, 2005). Minor revisions based on reviewers'
comments (June 23, 2006
Energy Consumption Models For MISO-UWB and TR-MISO-UWB Systems
in this paper, an energy consumption model is developed and exploited to evaluate the electrical energy consumption of ultra-wideband impulse radio (UWB-IR) systems. We develop the energy consumption models and our comparative study, on the one hand, for a system based single-input single-output (SISO) configuration and a multiple-input single-output (MISO) and, on the other hand, for a time reversal TR-MISO configuration and for MISO alone configuration. We consider an indoor propagation environment based on the 802.15.4a channel model. The results show very different behaviors depending on the propagation conditions, the number of antennas used, or on the number of transmitted symbols. Using such a model, a radiofrequency designer can obtain significant inputs to optimally select an adequate configuration to design an adaptive energy-aware UWB-IR system
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