Fast joint detection base station

Details Fast joint detection base station Fast joint detection base station

2002-02-20

2003-08-19

Bocure, Tesfaldet (Department: 2631)

Pulse or digital communications

Spread spectrum

Direct sequence

C375S150000, C370S342000

Reexamination Certificate

active

06608859

ABSTRACT:

BACKGROUND
The invention generally relates to wireless communication systems. In particular, the invention relates to data detection in a wireless communication system.
FIG. 1
is an illustration of a wireless communication system
10
. The communication system
10
has base stations
12
1
to
12
5
(
12
) which communicate with base stations
14
1
to
14
3
(
14
). Each base station
12
has an associated operational area, where it communicates with UEs
14
in its operational area.
In some communication systems, such as frequency division duplex using code division multiple access (FDD/CDMA) and time division duplex using code division multiple access (TDD/CDMA), multiple communications are sent over the same frequency spectrum. These communications are differentiated by their channelization codes. To more efficiently use the frequency spectrum, TDD/CDMA communication systems use repeating frames divided into timeslots for communication. A communication sent in such a system will have one or multiple associated codes and timeslots assigned to it.
Since multiple communications may be sent in the same frequency spectrum and at the same time, a receiver in such a system must distinguish between the multiple communications. One approach to detecting such signals is multiuser detection (MUD). In MUD, signals associated with all the UEs
14
, users, are detected simultaneously. Another approach to detecting a multi-code transmission from a single transmitter is single user detection (SUD). In SUD, to recover data from the multi-code transmission at the receiver, the received signal is passed through an equalization stage and despread using one or multiple codes. Approaches for implementing MUD and the equalization stage of SUD include using a Cholesky or an approximate Cholesky decomposition. These approaches have a high complexity. The high complexity leads to increased power consumption, which at the UE
14
results in reduced battery life. Accordingly, it is desirable to have alternate approaches to detecting received data.
SUMMARY
A code division multiple access base station receives K data signals over a shared spectrum. The base station receives and samples a combined signal having the K transmitted data signals. A combined channel response matrix is produced. A block column of a cross correlation matrix is determined using the combined channel response matrix. Each block entry of the block column is a K by K matrix. Each block entry of the block column is a K by K matrix. A fourier transform of a complex conjugate transpose of the combined channel response matrix multiplied to the combined signal samples is taken. An inverse of a fourier transform of each block entry is multiplied to a result of the fourier transform to produce a fourier transform of the data vector. An inverse fourier transform of the data vector fourier transform is taken to produce data of the K signals.


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patent: 6252540 (2001-06-01), Hale et al.
patent: 6370129 (2002-04-01), Huang
Anja Klein, Ghassan Kawas Kaleh and Paul Walter Baier, “Zero Forcing and Minimum Mean-Square-Error Equalization for Multiuser Detection in Code-Division Multiple-Access Channels,” IEEE Transactions on Vehicular Technology, vol. 45, No. 2, May 1996.
Anja Klein, “Data Detection Algorithms Specially Designed for the Downlink of CDMA Mobile Radio Systems,” IEEE 47th Vehicular Technology Conference, Phoenix, Arizona, USA, May 4-7, 1997.
H.R. Karimi and N.W. Anderson, “A Novel and Efficient Solution to Block-Based Joint-Detection Using Approximate Cholesky Factorization,” Motorola GSM Products Division, Swindon, UK, 1998.
PA Consulting Group/Racal Instruments Ltd., “Low Cost MMSE-BLE-SD Algorithm for UTRA TDD Mode Downlink,” ETSI STC SMG2 Layer 1 Expert Group, Helsinki, Finland Sep. 8-11, 1998.
Anja Klein and Paul W. Baier, “Linear Unbiased Data Estimation in Mobile Radio Systems Applying CDMA,” IEEE Journal on Selected Areas in Communications, vol. 11, No. 7, Sep. 1993.

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