© The Institution of Engineering and Technology
Here, the authors propose two adaptive detection schemes based on singlecarrier frequencydomain equalisation (SC‐FDE) for multiuser directsequence ultrawideband systems, which are termed structured channel estimation (SCE) and direct adaptation (DA). Both schemes use the minimum mean square error (MMSE) linear detection strategy and employ a cyclic prefix. In the SCE scheme, adaptive channel estimation is performed in the frequency domain and the despreading is implemented in the time domain after the FDE. In this scheme, the MMSE detection requires the knowledge of the number of users and the noise variance. For this purpose, simple algorithms are proposed for estimating these parameters. In the DA scheme, the interference suppression task is fulfilled with only one adaptive filter in the frequency domain and a new signal expression is adopted to simplify the design of such a filter. Least mean squares, recursive least squares and conjugate gradient adaptive algorithms are then developed for both schemes. A complexity analysis compares the computational complexity of the proposed algorithms and schemes, and simulation results for the downlink illustrate their performance.
References


1)

M.Z. Win ,
R.A. Scholtz
.
Impulse radio: how it works.
IEEE Commun. Lett.
,
2 ,
36 
38

2)

L. Yang ,
G.B. Giannakis
.
Ultrawideband communications: an idea whose time has come.
IEEE Signal Process. Mag.
,
6 ,
26 
54

3)

Federal Communications Commission: ‘First report and order FCC02048’ 2002.

4)

I. Oppermann ,
M. Hamalainen ,
J. Iinatti
.
(2004)
UWB theory and applications.

5)

Fisher, R., Kohno, R., McLaughlin, M., Welbourn, M.: `DSUWB physical layer submission to IEEE 802.15 Task Group 3a (Doc. Number P802.1504/0137r4)', IEEE P802.15, January 2005.

6)

D. Cassioli ,
M.Z. Win ,
F. Vatalaro ,
A.F. Molisch
.
Low complexity rake receivers in ultrawideband channels.
IEEE Trans. Wirel. Commun.
,
4 ,
1265 
1275

7)

P. Kaligineedi ,
V.K. Bhargava
.
Frequencydomain turbo equalization and multiuser detection for DSUWB systems.
IEEE Trans. Wirel. Commun.
,
9 ,
3280 
3284

8)

Y. Wang ,
X. Dong
.
Comparison of frequency offset and timing offset effects on the performance of SCFDE and OFDM over UWB channels.
IEEE Trans. Veh. Technol.
,
1 ,
242 
250

9)

Y. Wang ,
X. Dong
.
Frequencydomain channel estimation for SCFDE in UWB communications.
IEEE Trans. Commun.
,
12 ,
2155 
2163

10)

Chang, M.X., Yang, C.C.: `A novel architecture of singlecarrier block transmission DSCDMA', IEEE Vehicular Technology Conf. (VTC), September 2006.

11)

H. Sato ,
T. Ohtsuki
.
Frequency domain channel estimation and equalisation for direct sequenceultra wideband (DSUWB) system.
Proc. IEE Commun.
,
93 
98

12)

Tang, Y., Vucetic, B.: `The FFTbased multiuser detection for DSCDMA ultrawideband communication systems', Int. Workshop on Ultra Wideband, May 2004, p. 111–115.

13)

S. Morosi ,
T. Bianchi
.
Frequency domain dectectors for ultrawideband indoor communications.
IEEE Trans. Wirel. Commun.
,
10 ,
2654 
2658

14)

S. Haykin
.
(1996)
Adaptive filter theory.

15)

M. Morelli ,
L. Sanguinetti ,
U. Mengali
.
Channel estimation for adaptive frequencydomain equalization.
IEEE Trans. Wirel. Commun.
,
5 ,
2508 
2518

16)

D.G. Luenberger
.
(1989)
Linear and nonlinear programming.

17)

D.P. O'Leary
.
The block conjugate gradient algorithms and related methods.
Linear Algebra Appl.
,
293 
322

18)

J.S. Lim ,
C.K. Un
.
Block conjugate gradient algorithms for adaptive filtering.
Signal Process.
,
65 
77

19)

P. Chang ,
A.N. Willson
.
Analysis of conjugate gradient algorithms for adaptive filtering.
IEEE Trans. Signal Process.
,
2 ,
409 
418

20)

Ge, H., Scharf, L.L., Lundberg, M.: `Reducedrank multiuser detectors based on vector and matrix conjugate gradient Wiener filters', IEEE Fifth Workshop on Signal Processing in Wireless Communication, 2004, p. 189–193.

21)

A.S. Lalos ,
K. Berberidis
.
An efficient conjugate gradient method in the frequency domain: application to channel equalization.
Signal Process.
,
99 
116

22)

Younis, W.M., Dhahir, N.A., Sayed, A.H.: `Adaptive frequencydomain equalization of spacetime blockcoded transmissions', IEEE Int. Conf. on Acoustics, Speech, and Signal Process. (ICASSP), 2002.

23)

K. Siwiak ,
D. McKeown
.
(2004)
Ultrawideband radio technology.

24)

Molisch, A.F., Balakrishnan, K., Chong, C.C.: `IEEE 802.15.4a channel model: final report', Tech. IEEE Doc. 802.15040066202004a, 2005.

25)

A.F. Molisch ,
D. Cassioli ,
C.C. Chong
.
A comprehensive standardized model for ultrawideband propagation channels.
IEEE Trans. Antennas Propag.
,
11 ,
3151 
3166

26)

C.D. Meyer
.
(2000)
Matrix analysis and applied linear algebra.

27)

H. Sari ,
G. Karam ,
I. Jeanclaude
.
Transmission techniques for digital terrestrial TV broadcasting.
IEEE Commun. Mag.
,
2 ,
100 
109

28)

W.C. Wu ,
K.C. Chen
.
Identification of active users in synchronous CDMA multiuser detection.
IEEE J. Sel. Areas Commun.
,
9 ,
1723 
1735

29)

R.O. Schmidt
.
Multiple emitter location and signal parameter estimation.
IEEE Trans. Antennas Propag.
,
3 ,
276 
280
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