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| 2. |
- Johansson, Stefan, et al.
(författare)
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Implementation of an OFDM Synchronization Algorithm
- 1999
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Ingår i: 42nd Midwest Symposium on Circuits and Systems, 1999.. - 0780354915 ; 1, s. 228-231
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Konferensbidrag (refereegranskat)abstract
- In this paper, a implementation of an OFDM synchronization algorithm is presented. Both time and frequency offsets are estimated simultaneously, using the cyclic prefix. The algorithm is implemented on a commercial DSP, an FPGA and as an ASIC. It is shown that although the algorithm is too complex to be implemented on a standard DSP, a hardware architecture that is optimized for the algorithm can be implemented with moderate complexity
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| 3. |
- Johansson, Stefan, et al.
(författare)
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Silicon realization of an OFDM synchronization algorithm
- 1999
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Ingår i: The 6th IEEE International Conference on Electronics, Circuits and Systems, Proceedings of ICECS '99.. - 0780356829 ; 1, s. 319-322
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Konferensbidrag (refereegranskat)abstract
- n this paper a hardware architecture for an OFDM synchronizer is presented. The proposed synchronization unit can be used in any OFDM system that uses a cyclic prefix. The algorithm is based on the correlation introduced by the cyclic prefix, which is exploited in the time domain where both time and frequency offset are estimated simultaneously. The synchronization unit also performs frequency correction, which means that no feedback to the analog parts is necessary. Although the algorithm is too complex to be implemented on today's most powerful standard DSP, a hardware architecture that is optimized for the algorithm can be implemented with moderate complexity. The unit contains 32 kbit RAM and 5000 gates and the sample rate is 25 Msamples/s
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| 4. |
- Landström, Daniel, et al.
(författare)
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Symbol time offset estimation in coherent OFDM systems
- 1999
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Ingår i: IEEE International Conference on Communications. - Piscataway, NJ : IEEE Communications Society. - 078035284X ; , s. 500-505
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Konferensbidrag (refereegranskat)abstract
- This paper presents a symbol time offset estimator for coherent OFDM systems. This estimator exploits both the redundancy in the cyclic prefix and the pilot symbols used for channel estimation. The estimator is robust against frequency offsets and is suitable for use in dispersive channels. We base the estimator on the ML estimator for the AWGN channel. Simulations of an example system indicate a system performance as close as 0.3 dB to a perfectly synchronized system. Compared to an estimator not using pilots, our estimator's performance could allow a shorter cyclic prefix and thus a more spectrally efficient system.
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| 6. |
- van de Beek, Jan-Jaap, et al.
(författare)
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A time and frequency synchronization scheme for multiuser OFDM
- 1999
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Ingår i: IEEE Journal on Selected Areas in Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8716 .- 1558-0008. ; 17:11, s. 1900-1914
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Tidskriftsartikel (refereegranskat)abstract
- We present a multiuser synchronization scheme for tracking the mobile's uplink time and frequency offsets. It uses the redundancy introduced by the cyclic prefix and does not need additional pilots. We show performance results of an orthogonal frequency division multiplexing (OFDM)-based radio interface based on universal mobile telecommunication system (UMTS) parameters. For a UMTS-typical mobile channel environment, the performance of a coherent system employing the scheme is virtually indistinguishable from the performance of a perfectly synchronized system. In a differentially modulated system, synchronization errors decrease the system performance by about 0.7 dB compared to a perfectly synchronized system. Index Terms - Communication system, delay estimation, frequency estimation, multicarrier, multiuser system, orthogonal frequency division multiplexing (OFDM), synchronization, universal mobile telecommunication system (UMTS).
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