| 1. |
- Molisch, Andreas, et al.
(författare)
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A low-cost time-hopping impulse radio system for high data rate transmission
- 2005
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Ingår i: Eurasip Journal on Applied Signal Processing. - 1110-8657. ; :3, s. 397-412
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Tidskriftsartikel (refereegranskat)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.
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| 2. |
- Molisch, Andreas, et al.
(författare)
-
An efficient low-cost time-hopping impulse radio for high data rate transmission
- 2003
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Ingår i: Proceeding of the Sixth International Symposium on Wireless Personal Multimedia Communications.
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Konferensbidrag (refereegranskat)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. The system was proposed to the IEEE 802.15.3a group for standardization as high-datarate personal-area network (PAN). Key features are: (i) all-baseband implementation obviates the need for local oscillators and other passband components, (ii) all sampling and digital signal processing is done at 200MHz, (iii) fast acquisition is accomplished by novel search algorithms,(iv) the spectral can be shaped adaptively to accommodate different spectrum regulations and interference environments. We show that this system can provide 110Mbit/s at 7-10m distance, as well as higher data rates at shorter distances. Due to the spreading concept of time-hopping impulse radio, the system can sustain multiple piconets, and can suppress narrowband interference effectively.
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| 3. |
- Nakache, Y P, et al.
(författare)
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Low-complexity ultrawideband transceiver with compatibility to multiband-OFDM
- 2004
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Ingår i: International Workshop on Ultra Wideband Systems, 2004. Joint with Conference on Ultrawideband Systems and Technologies. Joint UWBST & IWUWBS.. - 0780383737 ; , s. 151-155
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Konferensbidrag (refereegranskat)abstract
- We present a low-complexity transceiver for ultrawideband communications with moderate (1-15 Mbit/s) data rate. This transceiver is based on time-frequency-interleaved frequency-shift-keying (TF-FSK), and shows a high degree of compatibility with multiband-OFDM, the currently envisioned standard for high-data-rate (>100 Mbit/s) UWB communications. We show that for dual-mode devices, the major part of the multiband-OFDM transceiver can be reused for the TF-FSK transceiver. We also study the performance of this transceiver in (standardized) UWB channels, and find that, depending on the data rate, coverage ranges of up to 30 m (with LOS connection) are possible.
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| 4. |
- Ramachandran, I, et al.
(författare)
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Symbol spreading for ultrawideband systems based on multiband OFDM
- 2004
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Ingår i: 15th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2004.. - 0780385233 ; 2, s. 1204-1209
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Konferensbidrag (refereegranskat)abstract
- We investigate the effect of symbol spreading on the performance of ultrawideband systems based on multiband OFDM. Ultrawideband channels offer the possibility of very high frequency diversity, as the used bandwidth is much larger than the coherence bandwidth of the channel. In multiband-OFDM, frequency diversity stems from (i) forward error correction coding, which distributes the symbols associated with one bit among different tones, and (ii) interleaving, which distributes the symbols among different employed frequency bands. We show that for weak (rate 3/4) error correcting codes, the achieved diversity order is insufficient. However, the use of Walsh-Hadamard spreading gives additional diversity within each frequency band and greatly improves the performance. Furthermore, we propose a novel scheme for grouping OFDM tones before the spreading is performed. This grouping gives additional flexibility in the system design.
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| 5. |
- Guvenc, I, et al.
(författare)
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Non-coherent TOA Estimation in IR-UWB Systems with Different Signal Waveforms
- 2005
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Ingår i: 2nd International Conference on Broadband Networks, 2005. - 0780392760 ; 2, s. 1168-1174
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Konferensbidrag (refereegranskat)abstract
- In this paper, signal waveform designs for TOA estimation with non-coherent receivers based on ultrawideband impulse radio are discussed. Four different transmit signal waveforms are analyzed, both with respect to their design constraints, and their precision ranging performance in IEEE 802.15.4a multipath channels. We introduce novel searchback and thresholding algorithms, and show that the ranging performance can be improved considerably with a-priori knowledge of noise variance. Simulation results show that it is possible to achieve sub-meter ranging accuracy with 90% confidence by using such energy detecting (non-coherent) receivers.
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| 6. |
- Orlik, P, et al.
(författare)
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A Hybrid UWB Modulation Design Compatible for both Coherent and Transmit-Reference Receivers
- 2006
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Ingår i: [Host publication title missing]. - 1424403553 ; , s. 4741-4745
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Konferensbidrag (refereegranskat)abstract
- In a pulsed UWB system, either coherent receivers or transmit-reference (TR) receivers can be used to demodulate the signals. For coherent receivers, which are typically based on a Rake Structure, the large number of resolvable multipaths is a major challenge for channel estimation and receiver complexity. TR receivers can effectively collect energy from all the received multipath components with much smaller complexity, but show reduced performance. Current modulation formats are tuned to either coherent or TR receivers, but cannot interoperate with both of them. In this paper, we propose an innovative modulation scheme that enables the useage of TR and coherent recievers in the same wireless network. The modulation allows demodulation by TR receivers, while at the same time enabling a coherent receiver to fully exploit all available signal energy, and actually to perform slightly better (by 1.8 dB) than a coherent receiver working with conventional BPSK modulation; this additional gain can be interpreted as a coding gain of a trellis-coded modulation scheme. The scheme thus allows the network designers to trade off performance vs. complexity in the receivers, while allowing a uniform signaling (modulation) scheme for all transmitters.
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| 7. |
- Sahinoglu, Z, et al.
(författare)
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Interference Suppression in Non-coherent Time-Hopping IR-UWB Ranging
- 2006
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Ingår i: The 2006 IEEE 2006 International Conference on Ultra-Wideband. - 1424401011 ; , s. 507-511
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Konferensbidrag (refereegranskat)abstract
- Ranging requires detection of the first arriving signal component. The accuracy of time-of-arrival-based range estimation is greatly degraded in the presence of multi-user interference (MUI). We develop a method that applies a nonlinear filter on received signal energy to suppress multiuser interference. Then, leading signal path is tracked via an iterative searchback algorithm. The method is tested on time-hopping impulse radio ultrawideband systems. Simulations conducted over IEEE 802.15.4a residential line of sight ultrawideband multipath channels indicate that range detection accuracy is significantly improved by the proposed non-linear filtering approach
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