Method and Apparatus for Diversity Transmission Scheme in Single-Carrier FDMA Systems
The disclosure relates to transmission of user data over multiple transmission layers in a wireless communication system with single-carrier orthogonal frequency division multiple access. A wireless terminal performs transform precoding on a vector of digital modulation symbols and the resulting complex-valued symbols are mapped to frequency/time/space resources. The digital modulation symbols are reordered, modified by a setting of complex-valued functions, and transform precoded. The resulting second set of complex-valued symbols are transform precoded and mapped to frequency/time/space resources.
1 . A method for a wireless communication device to transmit in a multi-layer Single-Carrier Frequency Division Multiple Access (SC-FDMA) system, the method comprising:
obtaining a first block of complex-valued symbols by transforming a first vector set of digital modulation symbols with a Discrete Fourier Transformation, wherein each digital modulation symbol corresponds to a unique transform code;
mapping the first block of complex-valued symbols onto a set of FDMA frequency resources of a first spatial layer in a first SC-FDMA symbol period;
obtaining a second vector of digital modulation symbols based on at least re-ordering the first vector of digital modulation symbols;
obtaining a second block of block of complex-valued symbols by transforming the second vector of digital modulation symbols with a Discrete Fourier Transformation; and
mapping the second block of complex-valued symbols onto a set of FDMA frequency resources of a second spatial layer in a second FDMA symbol period.
2 . The method of claim 1 , wherein each digital modulation symbol of both the first and second vectors corresponds to a unique transform code, the transform code depends on the position of the digital modulation symbol in the corresponding vector.
3 . The method of claim 1 , wherein obtaining the second vector of digital modulation symbols based on at least re-ordering the first vector of digital modulation symbols further comprises mapping at least one symbol in the first vector onto a different position in the second vector so that the corresponding transform code is distinct for the at least one symbol.
4 . The method of claim 1 , obtaining the second vector of digital modulation symbols further comprises:
pairing two digital modulation symbols of the first vector of digital modulation symbols to obtain a set of pairs;
reversing an order of the two symbols in each pair.
5 . The method of claim 4 , further comprising:
conjugating one symbol in each symbol pair;
conjugating and negating the other symbol in each symbol pair.
6 . The method of claim 1 , wherein obtaining the second vector of digital modulation symbols further comprises:
modifying one or more digital modulation symbols of the first vector of digital modulation symbols by at least conjugating and rotating a phase.
7 . The method of claim 1 , the first spatial layer in the first SC-FDMA symbol period and the second spatial layer in the second SC-FDMA symbol period correspond to the different spatial layers in the same symbol period.
8 . The method of claim 1 , the first spatial layer in the first SC-FDMA symbol period and the second spatial layer in the second SC-FDMA symbol period correspond to the same spatial layer in two different symbol periods.
9 . The method of claim 1 , the first spatial layer in the first SC-FDMA symbol period and the second spatial layer in the second SC-FDMA symbol period correspond to different spatial layers in two different symbol periods.
10 . The method of claim 1 , the frequency resources of the first spatial layer are the same as the frequency resources of the second spatial layer.
11 . The method of claim 1 , wherein mapping the first block of complex-valued symbols onto the set of SC-FDMA frequency resources of the first spatial layer and mapping the second block of complex-valued symbols onto the set of SC-FDMA frequency resources of the second spatial layer further comprises:
precoding the first and second blocks of complex-valued symbols according to a weighting indicated by a control message.
12 . A wireless communication device configured to transmit in a multi-layer Single-Carrier Frequency Division Multiple Access (SC-FDMA) system, the device comprising:
a transceiver;
a controller coupled to the transceiver,
the controller configured to obtain a first block of complex-valued symbols by transforming a first vector set of digital modulation symbols with a Discrete Fourier Transformation, wherein each digital modulation symbol corresponds to a unique transform code;
the controller configured to map the first block of complex-valued symbols onto a set of FDMA frequency resources of a first spatial layer in a first FDMA symbol period;
the controller configured to obtain a second vector of digital modulation symbols based on at least re-ordering the first vector of digital modulation symbols;
the controller configured to obtain a second block of block of complex-valued symbols by transforming the second vector of digital modulation symbols with a Discrete Fourier Transformation; and
the controller configured to map the second block of complex-valued symbols onto a set of SC-FDMA frequency resources of a second spatial layer in a second SC-FDMA symbol period.
13 . The device of claim 12 , wherein each digital modulation symbol of both the first and second vectors corresponds to a unique transform code, the transform code depends on the position of the digital modulation symbol in the corresponding vector of symbols.
14 . The device of claim 12 , wherein the controller is configured to obtain the second vector of digital modulation symbols based on at least re-ordering the first vector of digital modulation symbols by mapping at least one symbol in the first vector onto a different position in the second vector so that the corresponding transform code is distinct for the at least one symbol.
15 . The device of claim 12 , the controller configured to obtain the second vector of digital modulation symbols by pairing two digital modulation symbols of the first vector of digital modulation symbols to obtain a set of pairs and reversing an order of the two symbols in each pair.
16 . The device of claim 15 , the controller further configured to conjugate one symbol in each symbol pair, and conjugate and negate the other symbol in each symbol pair.
17 . The device of claim 12 , the controller configured to obtain the second vector of digital modulation symbols by at least conjugating and rotating a phase of one or more digital modulation symbols of the first vector of digital modulation symbols.
18 . The device of claim 12 , the first spatial layer in the first FDMA symbol period and the second spatial layer in the second FDMA symbol period correspond to the different spatial layers in the same symbol period.
19 . The device of claim 12 , the first spatial layer in the first SC-FDMA symbol period and the second spatial layer in the second SC-FDMA symbol period correspond to the same spatial layer in two different symbol periods.
20 . The device of claim 12 , the first spatial layer in the first SC-FDMA symbol period and the second spatial layer in the second SC-FDMA symbol period correspond to different spatial layers in two different symbol periods.
21 . The device of claim 12 , the frequency resources of the first spatial layer are the same as the frequency resources of the second spatial layer.
22 . The device of claim 12 , the controller configured to map the first block of complex-valued symbols onto the set of SC-FDMA frequency resources of the first spatial layer and map the second block of complex-valued symbols onto the set of SC-FDMA frequency resources of the second spatial layer by:
precoding the first and second blocks of complex-valued symbols according to a weighting indicated by a control message.
23 . A method for a wireless base unit to control transmission from a wireless device in a multi-layer Single-Carrier Frequency Division Multiple Access (SC-FDMA) system, the method comprising:
receiving, at the base unit, a vector set of digital modulation symbols from a wireless device;
the wireless base unit indicating to the wireless device to obtain a second vector set of digital modulation symbols based on at least re-ordering the first vector set of digital modulation symbols.
24 . The method of claim 23 wherein the wireless base unit indicating to the wireless device to obtain a second vector of digital modulation symbols based on at least re-ordering the first vector of digital modulation symbols further comprises indicating conjugating and rotating the phase of one or more digital modulation symbols of the first vector of digital modulation symbols.
25 . The method of claim 24 further comprising indicating the first spatial layer in a first SC-FDMA symbol period and the second spatial layer in a second SC-FDMA symbol period.