Method for determining beamforming parameters in a wireless communication system and to a wireless communication system
Inactive Publication Date: 2012-09-13
FRAUNHOFER GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG EV
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- Abstract
- Description
- Claims
- Application Information
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Benefits of technology
[0077]In accordance with an embodiment of the fourth aspect of the invention, the subsystems may be considered as beamforming systems and the beamformin
Problems solved by technology
Contrary to the beamforming signal processing, in MIMO signal processing (MIMO=Multiple-Input Multiple-Output), not only complex weightings but also costly digital signal processing operations need to be performed in every branch.
In contrast, systems using MIMO signal processing require a higher effort in the analog and digital circuitry and are hence generally limited to moderate numbers of antennas, e.g. to only 2 or 4 antennas.
Many known systems may use discrete (quantized) phase values only, so that the number of possible beamforming vectors is limited.
A problem for the operation of a multi-antenna system using beamforming is the adaptive (dynamic) adjustment of the beamforming vectors for maximizing the transmission quality in dependence on the propagation conditions.
In the latter case, estimating the channel matrix presents a significant additional challenge.
The following problem occurs when using a hybrid MIMO beamforming system with MIMO signal processing and beamforming signal processing according to FIG. 5:4. Determining suitable beamforming vectors at the transmitter and at the receiver in hybrid MIMO beamforming systems.
However, these direction-based methods may only be applied with little or non-existing multipath propagation.
Transferring such techniques to systems having only beamforming signal processing has not been possible so far, since, on the one hand, channel knowledge without side information (directional information) was not available for these systems and, on the other hand, it was unclear how a common beamforming vector is to be determined for all possibly different signal portions (in time and frequency).
The approach does include a transceiver architecture having several parallel transmitting and receiving branches in the digital baseband, however, no MIMO signal processing but beamforming signal processing is performed on the branches.
Method used
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[0087]In the following the different aspects of the invention will be described. It is noted that the respective aspects, while being described separately may be used in combination, e.g. in a wireless communication system the beamforming parameters may be determined applying one or more of the subsequently described aspects (approaches).
[0088]In the subsequent description, the following notation is used: Small letters in italics (e.g. a) describe complex- or real-valued quantities, capital letters in italics (e.g. A) describe complex- or real-valued constants, bold small letters (e.g. a) describe complex or real valued vectors, and bold capital letters (e.g. A) describe complex- or real-valued matrices. The dimensions of a matrix having N rows and M columns is N×M. The k-th element of vector a is indicated by [a]k, and [A]n,m is the element of the n-th row and m-th column of matrix A. A row vector having K elements that are each 1 is described as 11,K, a matrix having N rows and M ...
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A method for determining a beamforming vector or a beamforming channel matrix in a communication system including a transmitting station and a receiving station, and a communication system are described. The transmitting and receiving stations include respective antenna groups and respective codebooks include a plurality of predefined beamforming vectors for the antenna group.
Description
BACKGROUND[0001]Embodiments of the invention relate to a method for determining beamforming parameters in a wireless communication system, and to a wireless communication system. More specifically, embodiments of the invention may be used for improving the transmission in wireless communication systems and may be particularly interesting for mobile radio systems and wireless millimeter wave transmission systems.[0002]For improving the performance of wireless communication networks or radio systems, multi antenna techniques using group antennas (antenna arrays) at the transmitting side and at the receiving side may be used. One approach is called beamforming, and in accordance with this approach a signal is split at the transmitter and multiplied by a complex weighting factor (having a magnitude and a phase) for every transmitter antenna individually. At the receiver, the signals of the individual receiving antennas are also weighted with complex factors and added. Weighting the sign...
Claims
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Login to View More IPC IPC(8): H04B17/00
CPCH04B7/0617H04B7/0691H04B7/0413H04B7/0669H04B7/0482H04B7/0874H04B7/088H04B7/0465H04B7/0695
InventorKEUSGEN, WILHELMPETER, MICHAELKORTKE, ANDREAS
OwnerFRAUNHOFER GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG EV