CiteULike: dcastros Yoon

A Novel Unambiguous Multipath Mitigation Scheme for BOC(kn, n) Tracking in GNSS

Sanghun Kim — 2008-06-03T18:59:27-00:00

Applications and the Internet Workshops, 2007. SAINT Workshops 2007. International Symposium on (2007), pp. 57-57.

Binary offset carrier (BOC) signal tracking is one of the challenging problems in future global navigation satellite systems (GNSS) including Galileo and global positioning system (GPS), because false lock could be generated in the tracking procedure due to multiple side-peaks in BOC autocorrelation. Multipath mitigation is another challenging problem in GNSS systems, because the presence of multi-path signals gives a range error. Recently, a novel tracking scheme for the BOC signal was proposed by Garin [8]. However, it can not completely resolve the ambiguity problem due to the false lock and has not enough multipath mitigation performance. Moreover, Garin¿s scheme is applicable to only BOC(n, n). In this paper, we propose a novel unambiguous multipath mitigation scheme. The proposed scheme is applicable to various BOC signals (i.e., BOC(kn, n)) and does not incur false lock point in the tracking procedure. In addition, the proposed scheme has appropriate multipath mitigation performance than traditional and Garin¿s schemes.

Frequency synchronization in OFDM

Z Cvetkovic — 2008-05-21T10:54:25-00:00

Acoustics, Speech, and Signal Processing, 2004. Proceedings. (ICASSP '04). IEEE International Conference on, Vol. 4 (2004), pp. iv-373-iv-376 vol.4.

We present an OFDM frequency synchronization scheme. The scheme uses periodic OFDM symbols, similar to the algorithms proposed previously by Morelli and Mengali (1999) and Schmidl and Cox (1997). The proposed scheme attains considerably higher accuracy than the scheme by Schmidl and Cox requiring a similar computational load. Compared to the scheme by Morelli and Mengali, the proposed algorithm attains a somewhat inferior accuracy but at a significantly reduced computational complexity, i.e O(N) versus O(N/sup 2/) operations for N-tone OFDM. In addition to that, the scheme proposed here is considerably less sensitive to the accuracy of the involved computations than the other two schemes.

A DS-CDMA code acquisition scheme robust to residual code phase offset variation

Seokho Yoon — 2008-05-15T17:42:18-00:00

Vehicular Technology, IEEE Transactions on, Vol. 49, No. 6. (2000), pp. 2405-2418.

We first investigate the effect of residual code phase offset on the direct-sequence code-division multiple-access code acquisition scheme using a noncoherent matched filter receiver. We then propose a new code acquisition scheme that is robust to the variation of the residual code phase offset and outperforms the conventional scheme. When the code phase offset normalized to the chip duration between two sequences is within the advancing step size, the sum of two successive matched filter outputs has a constant value regardless of the residual code phase offset when the noise is absent. Based on this observation, we propose a new code acquisition scheme and investigate the performance of the scheme. The proposed code acquisition scheme is analyzed in an additive white Gaussian noise and multiple-access interference environment. Finally, numerical results are given to show that the proposed scheme is more robust to the variation of the residual code phase offset and has better performance than the conventional scheme on average

A code acquisition scheme for DS/CDMA systems

Seokho Yoon — 2008-05-15T17:42:10-00:00

Military Communications Conference Proceedings, 1999. MILCOM 1999. IEEE, Vol. 2 (1999), pp. 791-795 vol.2.

When the code phase offset between two sequences is within one chip duration, the sum of two successive matched filter outputs has a constant value regardless of the residual code phase offset if the noise is absent. Based on this observation, we propose a new code acquisition scheme, which is robust to the variation of the residual code phase offset and outperforms the conventional scheme. Numerical results are also given to show that the proposed scheme is more robust to the variation of the residual code phase offset and has better performance than the conventional scheme on average

A novel fully integrated transmitter front-end with high power-added efficiency

Hyungrak Kim — 2008-05-05T14:11:58-00:00

Microwave Theory and Techniques, IEEE Transactions on, Vol. 53, No. 10. (2005), pp. 3206-3214.

A novel fully integrated transmitter front-end with a simple structure is proposed to obtain both high power-added efficiency (PAE) and a compact RF-front structure. To have all these characteristics, a novel antenna operating as a radiator, a harmonic tuning circuit, and an output matching network of the power amplifier is proposed. Therefore, the direct integration of the output of the power amplifier and antenna can be achieved without any impedance transformers. From the measured results and fabrication, it is shown that the proposed transmitter front-end provides high PAE of 67.5% and compact and integrated RF-front structure by the size reduction of 43% compared with the conventional class-F active antenna for high PAE.

An efficient frequency offset estimator for OFDM systems and its performance characteristics

Yun Kim — 2007-11-11T16:34:18-00:00

Vehicular Technology, IEEE Transactions on, Vol. 50, No. 5. (2001), pp. 1307-1312.

In this paper, we propose a new frequency synchronization algorithm for orthogonal frequency division multiplexing (OFDM) systems requiring only one training symbol, based on a conventional method which requires two training symbols. While the timing synchronization is obtained by using the conventional method, the carrier frequency offset is efficiently estimated by the proposed method. It is shown that the proposed method not only reduces the number of the training symbols but also possesses better performance than the conventional method without increase in complexity