Constellation rearrangement for arq transmit diversity schemes

Abstract: An ARQ (re-) transmission method of transmitting data in a wireless communication system wherein data packets are transmitted from a transmitter to a receiver, using a first transmission and a second transmission based on a repeat request. The method comprises the steps of modulating data at the transmitter using a first signal constellation pattern to obtain a first data symbol. The first data symbol is transmitted as the first transmission to the receiver using a first diversity branch. Further, the data is modulated at the transmitter using a second signal constellation pattern to obtain a second data symbol. Then, the second data symbol is transmitted as the second transmission to the receive over a second diversity branch. Finally, the received first and second data symbol data symbol are diversity combined at the receiver. The invention further relates to a transmitter and a receiver embodied to carry out the method of the invention. (end of abstract)

Constellation rearrangement for arq transmit diversity schemes description/claims

Brief Patent Description

Full Patent Description

Patent Application Claims

This is a continuation of application Ser. No. 11/633,421 filed Dec. 5, 2006, which is a continuation of application Ser. No. 10/501,906 filed Jul. 20, 2004, which is a national phase application under 35 USC 371 of PCT/EP2002/011694 filed Oct. 18, 2002, the entire contents of each of which are incorporated by reference herein.

The present invention relates generally to ARQ (re-) transmission techniques in wireless communication systems and in particular to a method, transceiver and receiver using transmit diversity schemes wherein data packets are transmitted using a first and a second transmission based on a repeat request, and the bit-to-symbol mapping is performed differently for different transmitted diversity branches. The invention is particularly applicable to systems with unreliable and time-varying channel conditions resulting in an improved performance avoiding transmission errors.

There exist several well known transmit diversity techniques wherein one or several redundancy versions relating to identical data are transmitted on several (at least two) diversity branches “by default” without explicitly requesting (by a feedback channel) further diversity branches (as done in an ARQ scheme by requesting retransmissions). For example the following schemes are considered as transmit diversity:

- Site Diversity: The transmitted signal originates from different sites, e.g. different base stations in a cellular environment.
- Antenna Diversity: The transmitted signal originates from different antennas, e.g. different antennas of a multi-antenna base station.
- Polarization Diversity: The transmitted signal is mapped onto different polarizations.
- Frequency Diversity: The transmitted signal is mapped e.g. on different carrier frequencies or on different frequency hopping sequences.
- Time Diversity: The transmitted signal is e.g. mapped on different interleaving sequences.
- Multicode Diversity: The transmitted signal is mapped on different codes in e.g. a CDMA (Code Division Multiple Access) system.

There are known several diversity combining techniques. The following three techniques are the most common ones:

- Selection Combining: Selecting the diversity branch with the highest SNIP for decoding, ignoring the remaining ones.