Method for transmitting signals using antenna diversity, for instance in mobile communication systems, transmitter, receiver and computer program product therefor

A transmitter to transmit, via a first pair of antennas and at least one second pair of antennas, encoded digital symbols produced according to a modulation scheme, the transmitter comprising:

• a processing module configured to organize digital symbols in sets, at least one set from the sets of symbols that is used for transmission via said at least one second pair of antennas being swapped temporally by subsets of symbols with respect to the digital symbols used for transmission via said first pair of antennas;
• a first channel, coupled to said processing module, to provide a signal for the transmission via said first pair of antennas;
• wherein to provide said signal, said first channel includes:
• a first encoder adapted to subject said organized digital symbols to space-time coding;
• first spreading blocks coupled to said first encoder and adapted to subject said organized digital symbols to spreading with a code-division-multiple-access code and to scrambling with a scrambling code;
• and
• first adders coupled to said first spreading blocks to add respective pilot flows for channel estimation;
• and
• a second channel, coupled to said processing module, to provide a signal for the transmission via said second pair of antennas;
• wherein to provide said signal, said second channel includes:
• a second encoder adapted to subject said swapped temporally set of symbols to space-time coding;
• second spreading blocks coupled to said second encoder and adapted to subject said swapped temporally set of symbols to spreading with a code-division-multiple-access code and to scrambling with a scrambling code;
• and
• second adders coupled to said second spreading blocks to add respective pilot flows for channel estimation;
• wherein at least one between said code-division-multiple-access code and said scrambling code used for transmission via said at least one second pair of antennas is different from the code-division-multiple-access code and said scrambling code used for the transmission via said first pair of antennas.

A receiver to receive, via at least one antenna, encoded digital symbols transmitted via a first pair of antennas and at least one second pair of antennas, wherein:

• said digital symbols are organized in sets, at least one of the sets of symbols that is used for transmission via said at least one second pair of antennas being swapped temporally by subsets of symbols with respect to the digital symbols used for transmission via said first pair of antennas;
• for transmission of a signal via said first pair of antennas and for transmission of a signal via said at least one second pair of antennas, space-time coding is used and a same code-division-multiple-access code is used, while, for transmission via said first pair of antennas and for transmission via said at least one second pair of antennas, there are used scrambling codes that are different from one another;
• said receiver comprising at least one de-spreading device to eliminate, from received said transmitted signals, said scrambling codes that are different from one another;
• use, in addition to said first pair of antennas, a plurality of second pairs of antennas, sets of symbols used for transmission via said plurality of second pairs of antennas being swapped temporally by subsets of symbols with respect to the digital symbols used for transmission via said first pair of antennas;
• and use, for transmission via said plurality of second pairs of antennas, signals obtained by subjecting said swapped temporally sets of symbols to spreading with respective (CDMA) codes, to space-time coding, to scrambling with respective scrambling codes, and to adding with respective pilot flows for channel estimation;
• wherein at least one between said respective CDMA codes and said respective scrambling codes used for transmission via said plurality of second pairs of antennas is different from the CDMA code and said scrambling code used for transmission via said first pair of antennas.

A computer-readable medium having stored thereon a computer program product executable by at least one digital computer and which includes software code portions to perform, when the product is executed by the computer:

• organize digital symbols in sets, at least one set of the sets of symbols being usable for transmission via at least one second pair of antennas and being swapped temporally by subsets of symbols with respect to digital symbols usable for transmission via a first pair of antennas;
• use, for transmission via the first pair of antennas, a signal obtained by subjecting said organized digital symbols to spreading with a code-division-multiple-access (CDMA) code, to space-time coding, to scrambling with a scrambling code, and to adding with respective pilot flows for channel estimation;
• and use, for transmission via the at least one second pair of antennas, a signal obtained by subjecting said swapped temporally set of symbols to spreading with a CDMA code, to space-time coding, to scrambling with a scrambling code, and to adding with respective pilot flows for channel estimation;
• wherein at least one between the CDMA code and the scrambling code usable for transmission via the at least one second pair of antennas is different from the CDMA code and the scrambling code usable for transmission via the first pair of antennas;
• use, in addition to said first pair of antennas, a plurality of second pairs of antennas, sets of symbols used for transmission via said plurality of second pairs of antennas being swapped temporally by subsets of symbols with respect to the digital symbols used for transmission via said first pair of antennas;
• and use, for transmission via said plurality of second pairs of antennas, signals obtained by subjecting said swapped temporally sets of symbols to spreading with respective CDMA codes, to space-time coding, to scrambling with respective scrambling codes, and to adding with respective pilot flows for channel estimation;
• wherein at least one between said respective CDMA codes and said respective scrambling codes used for transmission via said plurality of second pairs of antennas is different from the CDMA code and said scrambling code used for transmission via said first pair of antennas.

A system for communicating, via a plurality of first antennas and a plurality of second antennas, digital symbols produced according to a modulation scheme, the system comprising:

• means for organizing digital symbols in sets, at least one set of the sets of symbols being usable for transmission via the second antennas and being swapped temporally by subsets of symbols with respect to digital symbols usable for transmission via the first antennas;
• means for using, for transmission via the first antennas, a signal obtained by subjecting said organized digital symbols to spreading with a first code, to space-time coding, to scrambling with a scrambling code, and to adding with respective pilot flows for channel estimation;
• and means for using, for transmission via the second antennas, a signal obtained by subjecting said swapped temporally set of symbols to spreading with a second code, to space- time coding, to scrambling with a scrambling code, and to adding with respective pilot flows for channel estimation;
• wherein at least one between the second code and the scrambling code usable for transmission via the second antennas is different from the first code and the scrambling code usable for transmission via the first antennas;
• means for using, in addition to said first pair of antennas, a plurality of second pairs of antennas, sets of symbols used for transmission via said plurality of second pairs of antennas being swapped temporally by subsets of symbols with respect to the digital symbols used for transmission via said first pair of antennas;
• and means for using, for transmission via said plurality of second pairs of antennas, signals obtained by subjecting said swapped temporally sets of symbols to spreading with respective code-division-multiple-access (CDMA) codes, to space-time coding, to scrambling with respective scrambling codes, and to adding with respective pilot flows for channel estimation;
• wherein at least one between said respective CDMA codes and said respective scrambling codes used for transmission via said plurality of second pairs of antennas is different from the CDMA code and said scrambling code used for transmission via said first pair of antennas.

An apparatus to transmit, via a plurality of first antennas and a plurality of second antennas, digital symbols produced according to a modulation scheme, the apparatus comprising:

• a processing module to organize the digital symbols in sets, at least one set of the sets of symbols being usable for transmission via the second antennas and being swapped temporally by subsets of symbols with respect to digital symbols usable for transmission via the first antennas;
• a first unit coupled to the processing module to generate, for transmission via the first antennas, a signal obtained by subjecting said organized digital symbols to spreading with a first code, to space-time coding, to scrambling with a scrambling code, and to adding with respective pilot flows for channel estimation;
• and a second unit coupled to the processing module to generate, for transmission via the second antennas, a signal obtained by subjecting said swapped temporally set of symbols to spreading with a second code, to space-time coding, to scrambling with a scrambling code, and to adding with respective pilot flows for channel estimation, wherein at least one between the second code and the scrambling code usable for transmission via the second antennas is different from the first code and the scrambling code usable for transmission via the first antennas;
• a third unit coupled to use, in addition to said first pair of antennas, a plurality of second pairs of antennas, sets of symbols used for transmission via said plurality of second pairs of antennas being swapped temporally by subsets of symbols with respect to the digital symbols used for transmission via said first pair of antennas;
• and a fourth unit coupled to generate, for transmission via said plurality of second pairs of antennas, signals obtained by subjecting said swapped temporally sets of symbols to spreading with respective code-division-multiple-access (CDMA) codes, to space-time coding, to scrambling with respective scrambling codes, and to adding with respective pilot flows for channel estimation;
• wherein at least one between said respective CDMA codes and said respective scrambling codes used for transmission via said plurality of second pairs of antennas is different from the (CDMA) code and said scrambling code used for transmission via said first pair of antennas.

A system in which digital symbols are communicated, the system comprising:

• at least one reception antenna to receive signals having the digital symbols, the digital symbols being transmitted via a first transmission antennas and second transmission antennas and being organized in sets, at least one set of the sets of symbols that is used for transmission via the second transmission antennas being swapped temporally by subsets of symbols with respect to the digital symbols used for transmission via the first transmission antennas;
• wherein for transmission via the first transmission antennas and for transmission via the second transmission antennas, space-time coding is used and at least one between code- division-multiple-access (CDMA) codes and scrambling codes are different;
• and at least one de-spreading device coupled to the at least one reception antenna to substantially eliminate, from the signals received by the at least one reception antenna, said scrambling codes that are different from one another;
• a plurality of second pairs of antennas, sets of symbols used for transmission via said plurality of second pairs of antennas being swapped temporally by subsets of symbols with respect to the digital symbols used for transmission via said first pair of antennas;
• and use, for transmission via said plurality of second pairs of antennas, signals obtained by subjecting said swapped temporally sets of symbols to spreading with respective CDMA codes, to space-time coding, to scrambling with respective scrambling codes, and to adding with respective pilot flows for channel estimation;
• wherein at least one between said respective CDMA codes and said respective scrambling codes used for transmission via said plurality of second pairs of antennas is different from the CDMA code and said scrambling code used for transmission via said first pair of antennas.