Method for distributed mobile communications, corresponding system and computer program product

• US 10,014,910 B2
• Filed: 12/30/2008
• Issued: 07/03/2018
• Est. Priority Date: 12/30/2008
• Status: Active Grant

• Current Assignee: Telecom Italia S.p.A.
• Original Assignee: Telecom Italia S.p.A.
• Inventors: Boldi, Mauro, Gianola, Paolo, Melis, Bruno, Ruscitto, Alfredo
• Primary Examiner(s): CHOWDHURY, HARUN UR R
• Application Number:
  US13/142,443
• Publication Number:
  US 20110268033A1
• Time in Patent Office: 3,472 Days
• Field of Search: 370310, 370320, 370334, 370335, 370342, 370343, 370344, 370252, 370328, 370210, 4555621, 455561, 375267
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04W 4/18 Information format or content conversion, e.g. adaptation by the network of the transmitted or received information for the purpose of wireless delivery to users or terminals
• CPC Class Codes: H04W 88/08 Access point devices
• CPC Class Codes: H04W 92/10 between terminal device and access point, i.e. wireless air interface

Abstract

A method of arranging exchange of signals between user terminals in a cellular communication system and at least one base station. The base station includes a central unit and a plurality of remote units. The signals are exchanged between the central unit and the remote units as aggregated signals for plural user terminals. The signals are processed at the remote units as distinct signals each associated with a respective one of the plural user terminals.

Claims

1. A method of arranging exchange of signals between user terminals in a cellular communication system and at least one base station comprising a central unit and a plurality of remote units, comprising:

performing a first baseband processing at said central unit, the first baseband processing including mapping signals for different user terminals in the time and frequency domains according to a mapping function resident in said central unit, the result of said mapping being organized in N_s resource grids filled with modulation symbols of different data and control channels according to said mapping function, where N_s is the number of resource grids at an output of the central unit;

exchanging the mapping function and the result of said mapping between said central unit and said remote units as an aggregated signal for plural user terminals in the frequency domain; and

performing a second baseband processing at said remote units based on the result of said mapping received from the central unit, the second baseband processing including performing a weight calculation while still in the frequency domain, applying said calculated weights to distinct signals each associated with a respective one of said plural user terminals based on said mapping function to perform adaptive beamforming on a per-user basis, and mapping the modulation symbols to inputs of an inverse Fast Fourier transform block within said remote units, said calculated weights being complex weights that are varied with respect to time and frequency and different for each user terminal.

2. The method of claim 1, wherein said signals are orthogonal frequency division multiple access signals.

3. The method of claim 1, wherein said aggregated signal for plural user terminals being exchanged between said central unit and said remote units are respective orthogonal frequency division multiple access signals in the frequency domain.

4. The method of claim 1, wherein said signals are code division multiple access signals.

5. The method of claim 4, comprising performing at said remote units at least one of:

a spreading operation on processed code division multiple access signals to be sent to said plural user terminals for converting said processed code division multiple access signals from symbol to chip level before said signals are processed at said remote units as distinct signals each associated with a respective one of said plural users; and

a despreading operation on the code division multiple access signals received from said plural user terminals for converting said received code division multiple access signals from chip to symbol level.

6. The method of claim 4, wherein said aggregated signal for plural users being exchanged between said central unit and said remote units are respective code division multiple access signals at symbol level.

7. The method of claim 4, wherein said aggregated signal for plural user terminals being transmitted from said central unit to said remote units are the respective code division multiple access signals at chip level, and wherein the method comprises performing at said remote units at least one despreading operation for converting said code division multiple access signals received from said central units from chip to symbol level before said signals are processed at said remote units as distinct signals each associated with a respective one of said plural user terminals.

8. A distributed antenna system for exchanging signals with user terminals in a cellular communication system, comprising a central unit and a plurality of remote units, wherein said distributed antenna system is configured for performing a method, comprising:

performing a first baseband processing at said central unit, the first baseband processing including mapping signals for different user terminals in the time and frequency domains according to a mapping function resident in said central unit, the result of said mapping being organized in N_s resource grids filled with modulation symbols of different data and control channels according to said mapping function, where N_s is the number of resource grids at an output of the central unit;

exchanging the mapping function and the result of said mapping between said central unit and said remote units as an aggregated signal for plural user terminals in the frequency domain; and

performing a second baseband processing at said remote units based on the result of said mapping received from the central unit, the second baseband processing including performing a weight calculation while still in the frequency domain, applying said calculated weights to distinct signals each associated with a respective one of said plural user terminals based on said mapping function to perform adaptive beamforming on a per-user basis, and mapping the modulation symbols to inputs of an inverse Fast Fourier transform block within said remote units, said calculated weights being complex weights that are varied with respect to time and frequency and different for each user terminal.

9. A non-transitory computer-readable medium storing a computer program product, loadable in a memory of at least one computer and comprising software code portions that when executed on a computer perform a method, comprising:

performing a first baseband processing at said central unit, the first baseband processing including mapping signals for different user terminals in the time and frequency domains according to a mapping function resident in said central unit, the result of said mapping being organized in N_s resource grids filled with modulation symbols of different data and control channels according to said mapping function, where N_s is the number of resource grids at an output of the central unit;

exchanging the mapping function and the result of said mapping between said central unit and said remote units as an aggregated signal for plural user terminals in the frequency domain; and

performing a second baseband processing at said remote units based on the result of said mapping received from the central unit, the second baseband processing including performing a weight calculation while still in the frequency domain, applying said calculated weights to distinct signals each associated with a respective one of said plural user terminals based on said mapping function to perform adaptive beamforminq on a per-user basis, and mapping the modulation symbols to inputs of an inverse Fast Fourier transform block within said remote units, said calculated weights being complex weights that are varied with respect to time and frequency and different for each user terminal.