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 (UE 1 , UE 2 ) to a plurality of coordinated reception points (BS A , BS B ) 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 (UE 1 , UE 2 ) to the coordinated reception points (BS A , BS B ), and compensating a timing difference between a propagation delay of a coordinated reception point (BS A , BS B ) which serves the user equipment (UE 1 , UE 2 ) and at least one propagation delay of at least one coordinated reception point (BS B , BS A ) which does not serve the user equipment (UE 1 , UE 2 ) 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 (UE 1 , UE 2 ) to the coordinated reception points (BS A , BS B ). The invention also relates to a processing arrangement (BS A , BS B , 2 ) adapted for performing the method.

1 . Method for joint processing of uplink data (g(n), s(n)) transmitted from at least one user equipment (UE 1 , UE 2 ) to a plurality of coordinated reception points (BS A , BS B ) 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 (UE 1 , UE 2 ) to the coordinated reception points (BS A , BS B ), and   compensating for a timing difference (τ) between a propagation delay of a coordinated reception point (BS A , BS B ) which serves the user equipment (UE 1 , UE 2 ) and at least one propagation delay of at least one coordinated reception point (BS B , BS A ) which does not serve the user equipment (UE 1 , UE 2 ) 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 (UE 1 , UE 2 ) to the coordinated reception points (BS A , BS B ) by performing a phase-shift on channel coefficients (h 1B , h 2A ) of the channel matrix (H) associated with non-serving coordinated reception points (BS B , BS A ), wherein the step of modifying the channel matrix (H) further comprises modifying an amplitude of the channel coefficients (h 1B , h 2A ) of the channel matrix (H) associated with the non-serving coordinated reception points (BS B , BS A ),   
     
     
         2 . Method according to  claim 1 , wherein the step of modifying the amplitude of the channel coefficients (h 1B , h 2A ) of the channel matrix (H) is performed by multiplying the channel coefficients (h 1B , h 2A ) with a real number smaller than one. 
     
     
         3 . Method according to  claim 1 , wherein uplink transmissions from the at least one user equipment (UE 1 , UE 2 ) to the coordinated reception points (BS A , BS B ) are performed in an orthogonal frequency division multiplex, OFDM, transmission scheme, an individual channel matrix (H) being preferably defined for each sub-carrier of the OFDM transmission scheme. 
     
     
         4 . Method according to  claim 1 , further comprising: performing a joint calculation of receiver antenna weights (G) for the plurality of user equipments (UE 1 , UE 2 ), the calculation being based on the modified cannel matrix (H MOD ). 
     
     
         5 . Method according to  claim 1 , further comprising:
 compensating the propagation delay from a user equipment (UE 1 ) to its serving coordinated reception point (BS A ) by adjusting the position of a processing window (W 1 ) for performing a time-to-frequency-domain transformation, in particular a Fast-Fourier-Transformation, FFT, on symbols (u 0 (n), u 1 (n), . . . ) of the uplink data (g(n)).   
     
     
         6 . Method according to  claim 1 , wherein the uplink data (g(n), s(n)) is transferred from the coordinated reception points (BS A , BS B ) to a centralized unit ( 2 ) for performing the joint processing, the uplink data (g(n), s(n)) being preferably transferred in the form of time domain or of frequency domain in-phase and quadrature-phase samples (a 0  to a 7 ), in particular together with information about the propagation delay from each user equipment (UE 1 , UE 2 ). 
     
     
         7 . Method according to  claim 1 , wherein 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 (g(n), s(n)) of a plurality of user equipments (UE 1 , UE 2 ) having similar propagation delays to a common non-serving reception point (BS C ).   
     
     
         8 . Method according to  claim 1 , further comprising: choosing the repetition rate for estimating the propagation delay in dependence of the speed of movement of the user equipment (UE 1 , UE 2 ). 
     
     
         9 . Method according to  claim 1 , wherein the joint processing comprises:
 performing a Fast-Fourier-Transformation, FFT, on a number of time domain samples (a 0  to a 7 ) of the uplink data (g(n), s(n)) in a processing window (W), the method preferably further comprising: shifting the processing window (W) by subtracting a discrete Fourier transform, DFT, contribution for each sub-carrier of one or more time domain samples (a 0 , a 1 ) at one end of the processing window (W) and adding a discrete Fourier transform, DFT, contribution for each sub-carrier of a corresponding number of time domain samples (a 6 , a 7 ) at the other end of the processing window (W).   
     
     
         10 . Processing arrangement (BS A , BS B ,  2 ) for joint processing of uplink data (s(n), g(n)) transmitted from at least one user equipment (UE 1 , UE 2 ) to a plurality of coordinated reception points (BS A , BS B ) of a wireless communication system ( 1 ),
 the processing arrangement being adapted to estimate and preferably to compensate individual propagation delays of the uplink data (s(n), g(n)) transmitted from one of the user equipments (UE 1 , UE 2 ) to the coordinated reception points (BS A , BS B ), the processing arrangement being further adapted to compensate a timing difference between a propagation delay of a coordinated reception point (BS B , BS A ) which serves the user equipment (UE 1 , UE 2 ) and a propagation delay of at least one coordinated reception point (BS A , BS B ) which does not serve the user equipment (UE 1 , UE 2 ) for performing the joint processing of the uplink data (s(n), g(n)), the processing arrangement being adapted to compensate the timing difference by modifying a channel matrix (H) associated with uplink channels from the at least one user equipment (UE 1 , UE 2 ) to the coordinated reception points (BS A , BS B ) by performing a phase-shift on channel coefficients (h 1B , h 2A ) of the channel matrix (H) associated with non-serving coordinated reception points (BS B , BS A ), the processing arrangement being further adapted for modifying an amplitude of the channel coefficients (h 1B , h 2A ) of the channel matrix (H) associated with the non-serving coordinated reception points (BS B , BS A ).   
     
     
         11 . Processing arrangement according to  claim 10 , being adapted for modifying the amplitude of the channel coefficients (h 1B , h 2A ) of the channel matrix (H) by multiplying the channel coefficients (h 1B , h 2A ) with a real number smaller than one. 
     
     
         12 . Processing arrangement according to  claim 10 , adapted to perform a joint calculation of receiver weights (G) for the plurality of user equipments (UE 1 , UE 2 ), the calculation being based on the modified cannel matrix (H MOD ). 
     
     
         13 . Processing arrangement according to  claim 10 , wherein the uplink data (s(n), g(n)) is transmitted from the at least one user equipment (UE 1 , UE 2 ) to the coordinated reception points (BS A , BS B ) in an orthogonal frequency division multiplex, OFDM, transmission scheme, and wherein the processing arrangement is preferably adapted to generate an individual channel matrix (H) for each sub-carrier of the OFDM transmission scheme. 
     
     
         14 . Base station (BS A , BS B ) comprising a processing arrangement according to  claim 10 . 
     
     
         15 . Wireless Communication Network ( 1 ) comprising at least one processing arrangement (BS A , BS B ,  2 ) according to  claim 10 .