Systematic water-filling for turbo coded CDMA packet data transmission over MIMO channels

It is known that the achievable capacity of wireless communications increases when multiple transmitter and receiver antennas are used. A step towards achieving MIMO capacity was taken by the introduction of the layered space-time architecture, also known as BLAST (Bell Laboratories layered space-time code), which advocates a simple demultiplexing of the data stream instead of some specific encoding in space-time, and does not require instantaneous channel information at the transmitter. When such channel information is available at the transmitter, however, the capacity of the link is increased. The PARC (per antenna rate control) method is an example of a technique that utilizes channel information for rate control of two separately encoded packets. In the literature, it has been shown that eigenbeamforming and water-filling are essential for achieving the relevant MIMO capacity. In this paper, we introduce a variant of water-filling called SWF-MIMO (systematic water-filling) for the transmission of an encoded packet across a MIMO channel by a simple extension of the current cdma2000 packet data structure. In this concept, we use the well-known fact that the reliability of the systematic part of a turbo code is crucial during the iterative decoding of the coded packet. The paper provides a detailed description of the SWF-MIMO algorithm and provides simulation results to compare the performance of the scheme with other MIMO schemes such as coded VBLAST and PARC.