Most existing space-time coding schemes assume time-invariant fading channels and offer antenna diversity gains relying on accurate channel estimates at the receiver. Recent single differential space-time block coding schemes forego channel estimation but are less effective in rapidly fading environments. Based on a diagonal unitary matrix group, a novel double differential space-time block coding approach is derived in this paper for time-selective fading channels. Without estimating the channels at the receiver, information symbols are recovered with antenna diversity gains regardless of frequency offsets. The resulting transceiver has very low complexity and is applicable to an arbitrary number of transmit and receive antennas. Approximately optimal space-time codes are also designed to minimize bit error rate. System performance is evaluated both analytically and with simulations.
Bibliographical noteFunding Information:
Paper approved by P. Hoeher, the Editor for Coding and Communication Theory of the IEEE Communications Society. Manuscript received March 20, 2000. This work was supported by the Army Research Office under Grant DAAG55-98-1-0336. The work of B. L. Hughes was supported in part by the National Science Foundation under Grant CCR-9903107 and Grant CCR-9805117, and by the Center for Advanced Computing and Communication. This paper was presented in part at the Wireless Communications and Networking Conference, Chicago, IL September 2000.
- Differential encoding
- Diversity methods
- Group codes
- Space-time codes
- Transmit antennas