Method and processing arrangement for joint processing of uplink data

Abstract

The invention relates to a method for joint processing of uplink data (g(n), s(n)) transmitted from at least one user equipment (UE1, UE2) to a plurality of coordinated reception points (BSA, BSB) of a wireless communication system (1), the method comprising: estimating and preferably compensating for individual propagation delays of the uplink data (g(n), s(n)) transmitted from one of the user equipments (UE1, UE2) to the coordinated reception points (BSA, BSB), and compensating a timing difference between a propagation delay of a coordinated reception point (BSA, BSB) which serves the user equipment (UE1, UE2) and at least one propagation delay of at least one coordinated reception point (BSB, BSA) which does not serve the user equipment (UE1, UE2) for performing the joint processing of the uplink data (g(n), s(n)), wherein the step of compensating the timing difference comprises modifying a channel matrix (H) associated with uplink channels from the at least one user equipment (UE1, UE2) to the coordinated reception points (BSA, BSB). The invention also relates to a processing arrangement (BSA, BSB, 2) adapted for performing the method.

Description

FIELD OF THE INVENTION[0001]The invention relates to the field of signal processing in wireless communication systems, and, in particular, to joint processing of uplink data transmitted from user equipments to coordinated reception points in wireless communication systems.BACKGROUND[0002]This section introduces aspects that may be helpful in facilitating a better understanding of the invention. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.[0003]When performing joint processing (JP) of uplink coordinated multi-point trans-missions (so-called COMP), one has to deal with multi-path propagations leading to different timing / propagation delays to the different reception points (e.g. base stations) of a COMP coordination cluster. If the difference of the timing offsets due to the different propagation delays exceeds the length reserved for the cyclic prefix ...

AI Technical Summary

Benefits of technology

[0007]For overcoming this problem, the inventors propose to perform a timing offset estimation also in the non-serving cells of the coordination cluster in order to detect the correct timing of the sub-frames and OFDM symbols per user equipment. Thus, the difference in the timing offsets / propagation delays between different cells can be taken into account and can be used to modify the channel matrix (per sub-carrier, see below) associated with the uplink transmissions for taking the timing difference into account. In such a way, joint processing may be performed even if the difference in the propagation delays from one user equipment to different reception points exceeds the length of the cyclic prefix being used in classical OFDMA-based systems. As this solution compensates the propagation delay differences of COMP cells, a type of cyclic prefix can be used that is appropriate for the multi-path propagation conditions, disregarding the timing offset to the non-serving COMP reception points. Hence, there is no need to increase the overhead when applying the COMP reception scheme.

[0013]In a further variant, the joint processing comprises: performing a joint time-to-frequency domain transformation, in particular a Fast-Fourier-Transformation, FFT, on time domain samples of the uplink data of a plurality of user equipments having similar propagation delays to a common non-serving reception point. When two or more user equipments are present which have a similar distance from the same reception point, a joint FFT may be performed for transforming time domain samples of the uplink data to frequency domain samples, thus reducing the overall number of FFTs being required for this purpose, and consequently also the complexity of the calculations. It will be understood that for this purpose, typically the user equipments will be grouped into different sets, each having a similar propagation delay.

[0019]The processing arrangement as described above allows for performing COMP using joint detection without having to increase the length of the cyclic prefix, thus increasing the throughput. It will be understood that in the most simple case, the processing arrangement may be implemented as a receiver for performing the joint processing. However, it may also be possible that the estimation and compensation of the propagation delay to the serving reception point may be performed at a different location as the compensation of the timing difference to the non-serving cells.

Problems solved by technology

However, when multiple user equipments have to be detected on the same multiple access (time / frequency / code) resource over several cells by multiple-input-multiple-output (MIMO) receiver strategies / multi-user detection, the problem occurs that the timing of the cells may be different.

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