Space–Time Line Code

Abstract

This paper characterizes rate-one (i.e., full rate) full-spatial-diversity-achieving communication schemes based on the channel state information (CSI) availability and antenna configurations, i.e., CSI at a transmitter (CSIT) or CSI at a receiver (CSIR) and the numbers of transmit and receive antennas M and N (denoted by M × N), respectively. The maximum ratio combining (MRC), maximum ratio transmission (MRT), and space-time block code (STBC) schemes are rate-one full-spatial-diversity-achieving method facilitated for communication systems with: 1) 1 × N and CSIR; 2) M × 1 and CSIT; and 3) M × 1 and CSIR, respectively. A novel space-time line code (STLC) is then introduced for a 1 × 2 system with CSIT, and it is extended to an M × 2 STLC. The proposed STLC uses CSI for encoding at the transmitter and enables the receiver to decode the STLC symbols without CSI. Also, the STLC encoding matrices with various code rates and decoding (combining) schemes are designed for the M × 3 and M × 4 STLC systems: A code rate of 3/4, 1/2, and 3/7 for the M × 3 systems and a code rate of 3/4, 4/7, and 1/2 for the M × 4 systems. For each STLC scheme, a full-diversity achieving STLC decoding method is designed. Based on analyses and numerical results, we verify that the proposed STLC scheme achieves a full diversity order, i.e., MN, and is robust against CSI uncertainty. It is also shown that the array processing gain is inversely proportional to the code rate. To verify the merit of STLC, we introduce a joint operation with STBC and STLC schemes, called an STBLC system. The STBLC system achieves full-spatial-diversity gain in both uplink and downlink communications. The new STLC achieving full-spatial diversity is scalable for various code rates and expected to be applied to various wireless communication systems along with MRC, MRT, and STBC.