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.

1 . A transmission method for use in an ARQ retransmission technique in a wireless communication system wherein data packets are transmitted to a receiver using a higher order modulation scheme wherein more than two data bits are mapped onto one data symbol to perform a first transmission and at least a second transmission based on a repeat request received from a receiver, the transmission method:
 modulating data packets using a first mapping of said higher order modulation scheme to obtain first data symbols;   performing, by a transmitter, the first transmission by transmitting the first data symbols over a first diversity branch to the receiver;   receiving the repeat request issued by the receiver to retransmit the data packets in case the data packets of the first transmission have not been successfully decoded,   wherein said modulating includes, in response to the received repeat request, modulating said data packets using a second mapping of said higher order modulation scheme to obtain second data symbols, and   wherein the transmission method further comprises:   performing, in response to the received repeat request, the second transmission by transmitting the second data symbols over a second diversity branch to the receiver, and   pre-storing the first mapping and the second mapping of said higher order modulation scheme in a memory table.   
   
   
       2 . The transmission method according to  claim 1 , wherein properties of the first and second mappings are obtained by (a) interleaving positions of the bits, in the bit sequence of the modulation scheme or (b) inverting bit values of the bits in the bit series of the modulation scheme. 
   
   
       3 . A transmission method for use in an ARQ retransmission technique in a wireless communication system wherein data packets are transmitted to a receiver using a higher order modulation scheme wherein more than two data bits are mapped onto one data symbol to perform a first transmission and at least a second transmission based on a repeat request received from a receiver, the transmission method comprising:
 modulating data packets using a first mapping of said higher order modulation scheme to obtain first data symbols;   performing the first transmission by transmitting the first data symbols over a first diversity branch to the receiver;   receiving the repeat request issued by the receiver to retransmit the data packets in case the data packets of the first transmission have not been successfully decoded,   wherein said modulating includes, in response to the received repeat request, modulating said data packets using a second mapping of said higher order modulation scheme to obtain second data symbols, and   wherein the transmission method further comprises:   performing in response to the received repeat request, the second transmission by transmitting the second data symbols over a second diversity branch to the receiver; and   signaling the first mapping and the second mapping of said higher order modulation scheme to the receiver.   
   
   
       4 . The transmission method according to  claim 3 , wherein properties of the first and second mappings are obtained by (a) interleaving positions of the bits, in the bit sequence of the modulation scheme or (b) inverting bit values of the bits in the bit series of the modulation scheme.